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Sample records for neural precursors mnp

  1. Culture of Mouse Neural Stem Cell Precursors

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    Currle, D. Spencer; Hu, Jia Sheng; Kolski-Andreaco, Aaron; Monuki, Edwin S.

    2007-01-01

    Primary neural stem cell cultures are useful for studying the mechanisms underlying central nervous system development. Stem cell research will increase our understanding of the nervous system and may allow us to develop treatments for currently incurable brain diseases and injuries. In addition, stem cells should be used for stem cell research aimed at the detailed study of mechanisms of neural differentiation and transdifferentiation and the genetic and environmental signals that direct the...

  2. Unique crystallization behavior of sodium manganese pyrophosphate Na2MnP2O7 glass and its electrochemical properties

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    Morito Tanabe

    2017-06-01

    Full Text Available Crystallization behavior of Na2MnP2O7 precursor glass was examined. Layered type Na2MnP2O7 was formed at 461 °C for 3 h in N2 filled electric furnace. Irreversible phase change was confirmed from layered Na2MnP2O7 to β-Na2MnP2O7 over 600 °C. At 650 °C crystallized phase was completely changed to β-phase. By means of charge and discharge testing it is found that layered Na2MnP2O7 is also active as cathode in sodium ion batteries. We found glass-ceramics technology is one of the suitable process for the synthesis of layered Na2MnP2O7 cathode without any complicate process.

  3. Brain Region-Dependent Rejection of Neural Precursor Cell Transplants

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    Nina Fainstein

    2018-04-01

    Full Text Available The concept of CNS as an immune-privileged site has been challenged by the occurrence of immune surveillance and allogeneic graft rejection in the brain. Here we examined whether the immune response to allogeneic neural grafts is determined by the site of implantation in the CNS. Dramatic regional differences were observed between immune responses to allogeneic neural precursor/stem cell (NPC grafts in the striatum vs. the hippocampus. Striatal grafts were heavily infiltrated with IBA-1+ microglia/macrophages and CD3+ T cells and completely rejected. In contrast, hippocampal grafts exhibited milder IBA-1+ cell infiltration, were not penetrated efficiently by CD3+ cells, and survived efficiently for at least 2 months. To evaluate whether the hippocampal protective effect is universal, astrocytes were then transplanted. Allogeneic astrocyte grafts elicited a vigorous rejection process from the hippocampus. CD200, a major immune-inhibitory signal, plays an important role in protecting grafts from rejection. Indeed, CD200 knock out NPC grafts were rejected more efficiently than wild type NPCs from the striatum. However, lack of CD200 expression did not elicit NPC graft rejection from the hippocampus. In conclusion, the hippocampus has partial immune-privilege properties that are restricted to NPCs and are CD200-independent. The unique hippocampal milieu may be protective for allogeneic NPC grafts, through host-graft interactions enabling sustained immune-regulatory properties of transplanted NPCs. These findings have implications for providing adequate immunosuppression in clinical translation of cell therapy.

  4. IGF-II Promotes Stemness of Neural Restricted Precursors

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    Ziegler, Amber N.; Schneider, Joel S.; Qin, Mei; Tyler, William A.; Pintar, John E.; Fraidenraich, Diego; Wood, Teresa L.; Levison, Steven W.

    2016-01-01

    Insulin-like growth factor (IGF)-I and IGF-II regulate brain development and growth through the IGF type 1 receptor (IGF-1R). Less appreciated is that IGF-II, but not IGF-I, activates a splice variant of the insulin receptor (IR) known as IR-A. We hypothesized that IGF-II exerts distinct effects from IGF-I on neural stem/progenitor cells (NSPs) via its interaction with IR-A. Immunofluorescence revealed high IGF-II in the medial region of the subventricular zone (SVZ) comprising the neural stem cell niche, with IGF-II mRNA predominant in the adjacent choroid plexus. The IGF-1R and the IR isoforms were differentially expressed with IR-A predominant in the medial SVZ, whereas the IGF-1R was more abundant laterally. Similarly, IR-A was more highly expressed by NSPs, whereas the IGF-1R was more highly expressed by lineage restricted cells. In vitro, IGF-II was more potent in promoting NSP expansion than either IGF-I or standard growth medium. Limiting dilution and differentiation assays revealed that IGF-II was superior to IGF-I in promoting stemness. In vivo, NSPs propagated in IGF-II migrated to and took up residence in periventricular niches while IGF-I-treated NSPs predominantly colonized white matter. Knockdown of IR or IGF-1R using shRNAs supported the conclusion that the IGF-1R promotes progenitor proliferation, whereas the IR is important for self-renewal. Q-PCR revealed that IGF-II increased Oct4, Sox1, and FABP7 mRNA levels in NSPs. Our data support the conclusion that IGF-II promotes the self-renewal of neural stem/progenitors via the IR. By contrast, IGF-1R functions as a mitogenic receptor to increase precursor abundance. PMID:22593020

  5. Replicable Expansion and Differentiation of Neural Precursors from Adult Canine Skin

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    Thomas Duncan

    2017-08-01

    Full Text Available Repopulation of brain circuits by neural precursors is a potential therapeutic strategy for neurodegenerative disorders; however, choice of cell is critical. Previously, we introduced a two-step culture system that generates a high yield of neural precursors from small samples of adult canine skin. Here, we probe their gene and protein expression profiles in comparison with dermal fibroblasts and brain-derived neural stem cells and characterize their neuronal potential. To date, we have produced >50 skin-derived neural precursor (SKN lines. SKNs can be cultured in a highly replicable fashion and uniformly express a panel of identifying markers. Upon differentiation, they self-upregulate neural specification genes, generating neurons with basic electrophysiological functionality. This unique population of neural precursors, derived from mature skin, overcomes many of the practical issues that have limited clinical translation of alternative cell types. Easily accessible, neuronally committed, and patient specific, SKNs may have potential for the treatment of brain disorders.

  6. GBM secretome induces transient transformation of human neural precursor cells.

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    Venugopal, Chitra; Wang, X Simon; Manoranjan, Branavan; McFarlane, Nicole; Nolte, Sara; Li, Meredith; Murty, Naresh; Siu, K W Michael; Singh, Sheila K

    2012-09-01

    Glioblastoma (GBM) is the most aggressive primary brain tumor in humans, with a uniformly poor prognosis. The tumor microenvironment is composed of both supportive cellular substrates and exogenous factors. We hypothesize that exogenous factors secreted by brain tumor initiating cells (BTICs) could predispose normal neural precursor cells (NPCs) to transformation. When NPCs are grown in GBM-conditioned media, and designated as "tumor-conditioned NPCs" (tcNPCs), they become highly proliferative and exhibit increased stem cell self-renewal, or the unique ability of stem cells to asymmetrically generate another stem cell and a daughter cell. tcNPCs also show an increased transcript level of stem cell markers such as CD133 and ALDH and growth factor receptors such as VEGFR1, VEGFR2, EGFR and PDGFRα. Media analysis by ELISA of GBM-conditioned media reveals an elevated secretion of growth factors such as EGF, VEGF and PDGF-AA when compared to normal neural stem cell-conditioned media. We also demonstrate that tcNPCs require prolonged or continuous exposure to the GBM secretome in vitro to retain GBM BTIC characteristics. Our in vivo studies reveal that tcNPCs are unable to form tumors, confirming that irreversible transformation events may require sustained or prolonged presence of the GBM secretome. Analysis of GBM-conditioned media by mass spectrometry reveals the presence of secreted proteins Chitinase-3-like 1 (CHI3L1) and H2A histone family member H2AX. Collectively, our data suggest that GBM-secreted factors are capable of transiently altering normal NPCs, although for retention of the transformed phenotype, sustained or prolonged secretome exposure or additional transformation events are likely necessary.

  7. Non-Viral Generation of Neural Precursor-like Cells from Adult Human Fibroblasts

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    Maucksch C

    2012-01-01

    Full Text Available Recent studies have reported direct reprogramming of human fibroblasts to mature neurons by the introduction of defined neural genes. This technology has potential use in the areas of neurological disease modeling and drug development. However, use of induced neurons for large-scale drug screening and cell-based replacement strategies is limited due to their inability to expand once reprogrammed. We propose it would be more desirable to induce expandable neural precursor cells directly from human fibroblasts. To date several pluripotent and neural transcription factors have been shown to be capable of converting mouse fibroblasts to neural stem/precursor-like cells when delivered by viral vectors. Here we extend these findings and demonstrate that transient ectopic insertion of the transcription factors SOX2 and PAX6 to adult human fibroblasts through use of non-viral plasmid transfection or protein transduction allows the generation of induced neural precursor (iNP colonies expressing a range of neural stem and pro-neural genes. Upon differentiation, iNP cells give rise to neurons exhibiting typical neuronal morphologies and expressing multiple neuronal markers including tyrosine hydroxylase and GAD65/67. Importantly, iNP-derived neurons demonstrate electrophysiological properties of functionally mature neurons with the capacity to generate action potentials. In addition, iNP cells are capable of differentiating into glial fibrillary acidic protein (GFAP-expressing astrocytes. This study represents a novel virus-free approach for direct reprogramming of human fibroblasts to a neural precursor fate.

  8. GH mediates exercise-dependent activation of SVZ neural precursor cells in aged mice.

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    Daniel G Blackmore

    Full Text Available Here we demonstrate, both in vivo and in vitro, that growth hormone (GH mediates precursor cell activation in the subventricular zone (SVZ of the aged (12-month-old brain following exercise, and that GH signaling stimulates precursor activation to a similar extent to exercise. Our results reveal that both addition of GH in culture and direct intracerebroventricular infusion of GH stimulate neural precursor cells in the aged brain. In contrast, no increase in neurosphere numbers was observed in GH receptor null animals following exercise. Continuous infusion of a GH antagonist into the lateral ventricle of wild-type animals completely abolished the exercise-induced increase in neural precursor cell number. Given that the aged brain does not recover well after injury, we investigated the direct effect of exercise and GH on neural precursor cell activation following irradiation. This revealed that physical exercise as well as infusion of GH promoted repopulation of neural precursor cells in irradiated aged animals. Conversely, infusion of a GH antagonist during exercise prevented recovery of precursor cells in the SVZ following irradiation.

  9. GH Mediates Exercise-Dependent Activation of SVZ Neural Precursor Cells in Aged Mice

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    Blackmore, Daniel G.; Vukovic, Jana; Waters, Michael J.; Bartlett, Perry F.

    2012-01-01

    Here we demonstrate, both in vivo and in vitro, that growth hormone (GH) mediates precursor cell activation in the subventricular zone (SVZ) of the aged (12-month-old) brain following exercise, and that GH signaling stimulates precursor activation to a similar extent to exercise. Our results reveal that both addition of GH in culture and direct intracerebroventricular infusion of GH stimulate neural precursor cells in the aged brain. In contrast, no increase in neurosphere numbers was observed in GH receptor null animals following exercise. Continuous infusion of a GH antagonist into the lateral ventricle of wild-type animals completely abolished the exercise-induced increase in neural precursor cell number. Given that the aged brain does not recover well after injury, we investigated the direct effect of exercise and GH on neural precursor cell activation following irradiation. This revealed that physical exercise as well as infusion of GH promoted repopulation of neural precursor cells in irradiated aged animals. Conversely, infusion of a GH antagonist during exercise prevented recovery of precursor cells in the SVZ following irradiation. PMID:23209615

  10. Enrichment of skin-derived neural precursor cells from dermal cell populations by altering culture conditions.

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    Bayati, Vahid; Gazor, Rohoullah; Nejatbakhsh, Reza; Negad Dehbashi, Fereshteh

    2016-01-01

    As stem cells play a critical role in tissue repair, their manipulation for being applied in regenerative medicine is of great importance. Skin-derived precursors (SKPs) may be good candidates for use in cell-based therapy as the only neural stem cells which can be isolated from an accessible tissue, skin. Herein, we presented a simple protocol to enrich neural SKPs by monolayer adherent cultivation to prove the efficacy of this method. To enrich neural SKPs from dermal cell populations, we have found that a monolayer adherent cultivation helps to increase the numbers of neural precursor cells. Indeed, we have cultured dermal cells as monolayer under serum-supplemented (control) and serum-supplemented culture, followed by serum free cultivation (test) and compared. Finally, protein markers of SKPs were assessed and compared in both experimental groups and differentiation potential was evaluated in enriched culture. The cells of enriched culture concurrently expressed fibronectin, vimentin and nestin, an intermediate filament protein expressed in neural and skeletal muscle precursors as compared to control culture. In addition, they possessed a multipotential capacity to differentiate into neurogenic, glial, adipogenic, osteogenic and skeletal myogenic cell lineages. It was concluded that serum-free adherent culture reinforced by growth factors have been shown to be effective on proliferation of skin-derived neural precursor cells (skin-NPCs) and drive their selective and rapid expansion.

  11. Neural precursors of future liking and affective reciprocity.

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    Zerubavel, Noam; Hoffman, Mark Anthony; Reich, Adam; Ochsner, Kevin N; Bearman, Peter

    2018-04-24

    Why do certain group members end up liking each other more than others? How does affective reciprocity arise in human groups? The prediction of interpersonal sentiment has been a long-standing pursuit in the social sciences. We combined fMRI and longitudinal social network data to test whether newly acquainted group members' reward-related neural responses to images of one another's faces predict their future interpersonal sentiment, even many months later. Specifically, we analyze associations between relationship-specific valuation activity and relationship-specific future liking. We found that one's own future (T2) liking of a particular group member is predicted jointly by actor's initial (T1) neural valuation of partner and by that partner's initial (T1) neural valuation of actor. These actor and partner effects exhibited equivalent predictive strength and were robust when statistically controlling for each other, both individuals' initial liking, and other potential drivers of liking. Behavioral findings indicated that liking was initially unreciprocated at T1 yet became strongly reciprocated by T2. The emergence of affective reciprocity was partly explained by the reciprocal pathways linking dyad members' T1 neural data both to their own and to each other's T2 liking outcomes. These findings elucidate interpersonal brain mechanisms that define how we ultimately end up liking particular interaction partners, how group members' initially idiosyncratic sentiments become reciprocated, and more broadly, how dyads evolve. This study advances a flexible framework for researching the neural foundations of interpersonal sentiments and social relations that-conceptually, methodologically, and statistically-emphasizes group members' neural interdependence. Copyright © 2018 the Author(s). Published by PNAS.

  12. Meninges harbor cells expressing neural precursor markers during development and adulthood.

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    Bifari, Francesco; Berton, Valeria; Pino, Annachiara; Kusalo, Marijana; Malpeli, Giorgio; Di Chio, Marzia; Bersan, Emanuela; Amato, Eliana; Scarpa, Aldo; Krampera, Mauro; Fumagalli, Guido; Decimo, Ilaria

    2015-01-01

    Brain and skull developments are tightly synchronized, allowing the cranial bones to dynamically adapt to the brain shape. At the brain-skull interface, meninges produce the trophic signals necessary for normal corticogenesis and bone development. Meninges harbor different cell populations, including cells forming the endosteum of the cranial vault. Recently, we and other groups have described the presence in meninges of a cell population endowed with neural differentiation potential in vitro and, after transplantation, in vivo. However, whether meninges may be a niche for neural progenitor cells during embryonic development and in adulthood remains to be determined. In this work we provide the first description of the distribution of neural precursor markers in rat meninges during development up to adulthood. We conclude that meninges share common properties with the classical neural stem cell niche, as they: (i) are a highly proliferating tissue; (ii) host cells expressing neural precursor markers such as nestin, vimentin, Sox2 and doublecortin; and (iii) are enriched in extracellular matrix components (e.g., fractones) known to bind and concentrate growth factors. This study underlines the importance of meninges as a potential niche for endogenous precursor cells during development and in adulthood.

  13. Microglia modulate hippocampal neural precursor activity in response to exercise and aging.

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    Vukovic, Jana; Colditz, Michael J; Blackmore, Daniel G; Ruitenberg, Marc J; Bartlett, Perry F

    2012-05-09

    Exercise has been shown to positively augment adult hippocampal neurogenesis; however, the cellular and molecular pathways mediating this effect remain largely unknown. Previous studies have suggested that microglia may have the ability to differentially instruct neurogenesis in the adult brain. Here, we used transgenic Csf1r-GFP mice to investigate whether hippocampal microglia directly influence the activation of neural precursor cells. Our results revealed that an exercise-induced increase in neural precursor cell activity was mediated via endogenous microglia and abolished when these cells were selectively removed from hippocampal cultures. Conversely, microglia from the hippocampi of animals that had exercised were able to activate latent neural precursor cells when added to neurosphere preparations from sedentary mice. We also investigated the role of CX(3)CL1, a chemokine that is known to provide a more neuroprotective microglial phenotype. Intraparenchymal infusion of a blocking antibody against the CX(3)CL1 receptor, CX(3)CR1, but not control IgG, dramatically reduced the neurosphere formation frequency in mice that had exercised. While an increase in soluble CX(3)CL1 was observed following running, reduced levels of this chemokine were found in the aged brain. Lower levels of CX(3)CL1 with advancing age correlated with the natural decline in neural precursor cell activity, a state that could be partially alleviated through removal of microglia. These findings provide the first direct evidence that endogenous microglia can exert a dual and opposing influence on neural precursor cell activity within the hippocampus, and that signaling through the CX(3)CL1-CX(3)CR1 axis critically contributes toward this process.

  14. Probabilistic neural network algorithm for using radon emanations as an earthquake precursor

    International Nuclear Information System (INIS)

    Gupta, Dhawal; Shahani, D.T.

    2014-01-01

    The investigation throughout the world in past two decades provides evidence which indicate that significance variation of radon and other soil gases occur in association with major geophysical events such as earthquake. The traditional statistical algorithm includes regression to remove the effect of the meteorological parameters from the raw radon and anomalies are calculated either taking the periodicity in seasonal variations or periodicity computed using Fast Fourier Transform. In case of neural networks the regression step is avoided. A neural network model can be found which can learn the behavior of radon with respect to meteorological parameter in order that changing emission patterns may be adapted to by the model on its own. The output of this neural model is the estimated radon values. This estimated radon value is used to decide whether anomalous behavior of radon has occurred and a valid precursor may be identified. The neural network model developed using Radial Basis function network gave a prediction rate of 87.7%. The same was accompanied by huge false alarms. The present paper deals with improved neural network algorithm using Probabilistic Neural Networks that requires neither an explicit step of regression nor use of any specific period. This neural network model reduces the false alarms to zero and gave same prediction rate as RBF networks. (author)

  15. Precursors predicted by artificial neural networks for mass balance calculations: Quantifying hydrothermal alteration in volcanic rocks

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    Trépanier, Sylvain; Mathieu, Lucie; Daigneault, Réal; Faure, Stéphane

    2016-04-01

    This study proposes an artificial neural networks-based method for predicting the unaltered (precursor) chemical compositions of hydrothermally altered volcanic rock. The method aims at predicting precursor's major components contents (SiO2, FeOT, MgO, CaO, Na2O, and K2O). The prediction is based on ratios of elements generally immobile during alteration processes; i.e. Zr, TiO2, Al2O3, Y, Nb, Th, and Cr, which are provided as inputs to the neural networks. Multi-layer perceptron neural networks were trained on a large dataset of least-altered volcanic rock samples that document a wide range of volcanic rock types, tectonic settings and ages. The precursors thus predicted are then used to perform mass balance calculations. Various statistics were calculated to validate the predictions of precursors' major components, which indicate that, overall, the predictions are precise and accurate. For example, rank-based correlation coefficients were calculated to compare predicted and analysed values from a least-altered test dataset that had not been used to train the networks. Coefficients over 0.87 were obtained for all components, except for Na2O (0.77), indicating that predictions for alkali might be less performant. Also, predictions are performant for most volcanic rock compositions, except for ultra-K rocks. The proposed method provides an easy and rapid solution to the often difficult task of determining appropriate volcanic precursor compositions to rocks modified by hydrothermal alteration. It is intended for large volcanic rock databases and is most useful, for example, to mineral exploration performed in complex or poorly known volcanic settings. The method is implemented as a simple C++ console program.

  16. Long-term culture and differentiation of CNS precursors derived from anterior human neural rosettes following exposure to ventralizing factors

    International Nuclear Information System (INIS)

    Colleoni, Silvia; Galli, Cesare; Giannelli, Serena G.; Armentero, Marie-Therese; Blandini, Fabio; Broccoli, Vania; Lazzari, Giovanna

    2010-01-01

    In this study we demonstrated that neural rosettes derived from human ES cells can give rise either to neural crest precursors, following expansion in presence of bFGF and EGF, or to dopaminergic precursors after exposure to ventralizing factors Shh and FGF8. Both regionalised precursors are capable of extensive proliferation and differentiation towards the corresponding terminally differentiated cell types. In particular, peripheral neurons, cartilage, bone, smooth muscle cells and also pigmented cells were obtained from neural crest precursors while tyrosine hydroxylase and Nurr1 positive dopaminergic neurons were derived from FGF8 and Shh primed rosette cells. Gene expression and immunocytochemistry analyses confirmed the expression of dorsal and neural crest genes such as Sox10, Slug, p75, FoxD3, Pax7 in neural precursors from bFGF-EGF exposed rosettes. By contrast, priming of rosettes with FGF8 and Shh induced the expression of dopaminergic markers Engrailed1, Pax2, Pitx3, floor plate marker FoxA2 and radial glia markers Blbp and Glast, the latter in agreement with the origin of dopaminergic precursors from floor plate radial glia. Moreover, in vivo transplant of proliferating Shh/FGF8 primed precursors in parkinsonian rats demonstrated engraftment and terminal dopaminergic differentiation. In conclusion, we demonstrated the derivation of long-term self-renewing precursors of selected regional identity as potential cell reservoirs for cell therapy applications, such as CNS degenerative diseases, or for the development of toxicological tests.

  17. Long-term culture and differentiation of CNS precursors derived from anterior human neural rosettes following exposure to ventralizing factors

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    Colleoni, Silvia, E-mail: silviacolleoni@avantea.it [Laboratorio di Tecnologie della Riproduzione, Avantea, Via Porcellasco 7/f, 26100 Cremona (Italy); Galli, Cesare [Laboratorio di Tecnologie della Riproduzione, Avantea, Via Porcellasco 7/f, 26100 Cremona (Italy); Dipartimento Clinico Veterinario, Universita di Bologna, Via Tolara di Sopra 50, 40064 Ozzano Emilia (Italy); Giannelli, Serena G. [Stem Cells and Neurogenesis Unit, Division of Neuroscience, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan (Italy); Armentero, Marie-Therese; Blandini, Fabio [Laboratory of Functional Neurochemistry, Interdepartmental Research Center for Parkinson' s Disease, Neurological Institute C. Mondino, Via Mondino 2, 27100 Pavia (Italy); Broccoli, Vania, E-mail: broccoli.vania@hsr.it [Stem Cells and Neurogenesis Unit, Division of Neuroscience, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan (Italy); Lazzari, Giovanna, E-mail: giovannalazzari@avantea.it [Laboratorio di Tecnologie della Riproduzione, Avantea, Via Porcellasco 7/f, 26100 Cremona (Italy)

    2010-04-15

    In this study we demonstrated that neural rosettes derived from human ES cells can give rise either to neural crest precursors, following expansion in presence of bFGF and EGF, or to dopaminergic precursors after exposure to ventralizing factors Shh and FGF8. Both regionalised precursors are capable of extensive proliferation and differentiation towards the corresponding terminally differentiated cell types. In particular, peripheral neurons, cartilage, bone, smooth muscle cells and also pigmented cells were obtained from neural crest precursors while tyrosine hydroxylase and Nurr1 positive dopaminergic neurons were derived from FGF8 and Shh primed rosette cells. Gene expression and immunocytochemistry analyses confirmed the expression of dorsal and neural crest genes such as Sox10, Slug, p75, FoxD3, Pax7 in neural precursors from bFGF-EGF exposed rosettes. By contrast, priming of rosettes with FGF8 and Shh induced the expression of dopaminergic markers Engrailed1, Pax2, Pitx3, floor plate marker FoxA2 and radial glia markers Blbp and Glast, the latter in agreement with the origin of dopaminergic precursors from floor plate radial glia. Moreover, in vivo transplant of proliferating Shh/FGF8 primed precursors in parkinsonian rats demonstrated engraftment and terminal dopaminergic differentiation. In conclusion, we demonstrated the derivation of long-term self-renewing precursors of selected regional identity as potential cell reservoirs for cell therapy applications, such as CNS degenerative diseases, or for the development of toxicological tests.

  18. Adult subependymal neural precursors, but not differentiated cells, undergo rapid cathodal migration in the presence of direct current electric fields.

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    Robart Babona-Pilipos

    Full Text Available BACKGROUND: The existence of neural stem and progenitor cells (together termed neural precursor cells in the adult mammalian brain has sparked great interest in utilizing these cells for regenerative medicine strategies. Endogenous neural precursors within the adult forebrain subependyma can be activated following injury, resulting in their proliferation and migration toward lesion sites where they differentiate into neural cells. The administration of growth factors and immunomodulatory agents following injury augments this activation and has been shown to result in behavioural functional recovery following stroke. METHODS AND FINDINGS: With the goal of enhancing neural precursor migration to facilitate the repair process we report that externally applied direct current electric fields induce rapid and directed cathodal migration of pure populations of undifferentiated adult subependyma-derived neural precursors. Using time-lapse imaging microscopy in vitro we performed an extensive single-cell kinematic analysis demonstrating that this galvanotactic phenomenon is a feature of undifferentiated precursors, and not differentiated phenotypes. Moreover, we have shown that the migratory response of the neural precursors is a direct effect of the electric field and not due to chemotactic gradients. We also identified that epidermal growth factor receptor (EGFR signaling plays a role in the galvanotactic response as blocking EGFR significantly attenuates the migratory behaviour. CONCLUSIONS: These findings suggest direct current electric fields may be implemented in endogenous repair paradigms to promote migration and tissue repair following neurotrauma.

  19. Sequence conservation and combinatorial complexity of Drosophila neural precursor cell enhancers

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    Kuzin Alexander

    2008-08-01

    Full Text Available Abstract Background The presence of highly conserved sequences within cis-regulatory regions can serve as a valuable starting point for elucidating the basis of enhancer function. This study focuses on regulation of gene expression during the early events of Drosophila neural development. We describe the use of EvoPrinter and cis-Decoder, a suite of interrelated phylogenetic footprinting and alignment programs, to characterize highly conserved sequences that are shared among co-regulating enhancers. Results Analysis of in vivo characterized enhancers that drive neural precursor gene expression has revealed that they contain clusters of highly conserved sequence blocks (CSBs made up of shorter shared sequence elements which are present in different combinations and orientations within the different co-regulating enhancers; these elements contain either known consensus transcription factor binding sites or consist of novel sequences that have not been functionally characterized. The CSBs of co-regulated enhancers share a large number of sequence elements, suggesting that a diverse repertoire of transcription factors may interact in a highly combinatorial fashion to coordinately regulate gene expression. We have used information gained from our comparative analysis to discover an enhancer that directs expression of the nervy gene in neural precursor cells of the CNS and PNS. Conclusion The combined use EvoPrinter and cis-Decoder has yielded important insights into the combinatorial appearance of fundamental sequence elements required for neural enhancer function. Each of the 30 enhancers examined conformed to a pattern of highly conserved blocks of sequences containing shared constituent elements. These data establish a basis for further analysis and understanding of neural enhancer function.

  20. Inhibition of glycogen synthase kinase-3 enhances the differentiation and reduces the proliferation of adult human olfactory epithelium neural precursors

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    Manceur, Aziza P. [Institute of Biomaterials and Biomedical Engineering (IBBME), University of Toronto, Toronto, Ontario (Canada); Donnelly Centre, University of Toronto, Toronto, Ontario (Canada); Tseng, Michael [Laboratory of Cellular and Molecular Pathophysiology, Centre for Addiction and Mental Health (CAMH), University of Toronto, Toronto, Ontario (Canada); Department of Psychiatry, University of Toronto, Toronto, ON (Canada); Institute of Medical Science, University of Toronto, Toronto, ON (Canada); Holowacz, Tamara [Donnelly Centre, University of Toronto, Toronto, Ontario (Canada); Witterick, Ian [Institute of Medical Science, University of Toronto, Toronto, ON (Canada); Department of Otolaryngology, Head and Neck Surgery, University of Toronto, ON (Canada); Weksberg, Rosanna [Institute of Medical Science, University of Toronto, Toronto, ON (Canada); The Hospital for Sick Children, Research Institute, Program in Genetics and Genomic Biology, Toronto, Ontario Canada (Canada); McCurdy, Richard D. [The Hospital for Sick Children, Research Institute, Program in Genetics and Genomic Biology, Toronto, Ontario Canada (Canada); Warsh, Jerry J. [Laboratory of Cellular and Molecular Pathophysiology, Centre for Addiction and Mental Health (CAMH), University of Toronto, Toronto, Ontario (Canada); Department of Psychiatry, University of Toronto, Toronto, ON (Canada); Institute of Medical Science, University of Toronto, Toronto, ON (Canada); Audet, Julie, E-mail: julie.audet@utoronto.ca [Institute of Biomaterials and Biomedical Engineering (IBBME), University of Toronto, Toronto, Ontario (Canada); Donnelly Centre, University of Toronto, Toronto, Ontario (Canada)

    2011-09-10

    The olfactory epithelium (OE) contains neural precursor cells which can be easily harvested from a minimally invasive nasal biopsy, making them a valuable cell source to study human neural cell lineages in health and disease. Glycogen synthase kinase-3 (GSK-3) has been implicated in the etiology and treatment of neuropsychiatric disorders and also in the regulation of murine neural precursor cell fate in vitro and in vivo. In this study, we examined the impact of decreased GSK-3 activity on the fate of adult human OE neural precursors in vitro. GSK-3 inhibition was achieved using ATP-competitive (6-bromoindirubin-3'-oxime and CHIR99021) or substrate-competitive (TAT-eIF2B) inhibitors to eliminate potential confounding effects on cell fate due to off-target kinase inhibition. GSK-3 inhibitors decreased the number of neural precursor cells in OE cell cultures through a reduction in proliferation. Decreased proliferation was not associated with a reduction in cell survival but was accompanied by a reduction in nestin expression and a substantial increase in the expression of the neuronal differentiation markers MAP1B and neurofilament (NF-M) after 10 days in culture. Taken together, these results suggest that GSK-3 inhibition promotes the early stages of neuronal differentiation in cultures of adult human neural precursors and provide insights into the mechanisms by which alterations in GSK-3 signaling affect adult human neurogenesis, a cellular process strongly suspected to play a role in the etiology of neuropsychiatric disorders.

  1. Inhibition of glycogen synthase kinase-3 enhances the differentiation and reduces the proliferation of adult human olfactory epithelium neural precursors

    International Nuclear Information System (INIS)

    Manceur, Aziza P.; Tseng, Michael; Holowacz, Tamara; Witterick, Ian; Weksberg, Rosanna; McCurdy, Richard D.; Warsh, Jerry J.; Audet, Julie

    2011-01-01

    The olfactory epithelium (OE) contains neural precursor cells which can be easily harvested from a minimally invasive nasal biopsy, making them a valuable cell source to study human neural cell lineages in health and disease. Glycogen synthase kinase-3 (GSK-3) has been implicated in the etiology and treatment of neuropsychiatric disorders and also in the regulation of murine neural precursor cell fate in vitro and in vivo. In this study, we examined the impact of decreased GSK-3 activity on the fate of adult human OE neural precursors in vitro. GSK-3 inhibition was achieved using ATP-competitive (6-bromoindirubin-3'-oxime and CHIR99021) or substrate-competitive (TAT-eIF2B) inhibitors to eliminate potential confounding effects on cell fate due to off-target kinase inhibition. GSK-3 inhibitors decreased the number of neural precursor cells in OE cell cultures through a reduction in proliferation. Decreased proliferation was not associated with a reduction in cell survival but was accompanied by a reduction in nestin expression and a substantial increase in the expression of the neuronal differentiation markers MAP1B and neurofilament (NF-M) after 10 days in culture. Taken together, these results suggest that GSK-3 inhibition promotes the early stages of neuronal differentiation in cultures of adult human neural precursors and provide insights into the mechanisms by which alterations in GSK-3 signaling affect adult human neurogenesis, a cellular process strongly suspected to play a role in the etiology of neuropsychiatric disorders.

  2. Nanodiamonds with silicon vacancy defects for nontoxic photostable fluorescent labeling of neural precursor cells.

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    Merson, Tobias D; Castelletto, Stefania; Aharonovich, Igor; Turbic, Alisa; Kilpatrick, Trevor J; Turnley, Ann M

    2013-10-15

    Nanodiamonds (NDs) containing silicon vacancy (SiV) defects were evaluated as a potential biomarker for the labeling and fluorescent imaging of neural precursor cells (NPCs). SiV-containing NDs were synthesized using chemical vapor deposition and silicon ion implantation. Spectrally, SiV-containing NDs exhibited extremely stable fluorescence and narrow bandwidth emission with an excellent signal to noise ratio exceeding that of NDs containing nitrogen-vacancy centers. NPCs labeled with NDs exhibited normal cell viability and proliferative properties consistent with biocompatibility. We conclude that SiV-containing NDs are a promising biomedical research tool for cellular labeling and optical imaging in stem cell research.

  3. Purification of human induced pluripotent stem cell-derived neural precursors using magnetic activated cell sorting.

    Science.gov (United States)

    Rodrigues, Gonçalo M C; Fernandes, Tiago G; Rodrigues, Carlos A V; Cabral, Joaquim M S; Diogo, Maria Margarida

    2015-01-01

    Neural precursor (NP) cells derived from human induced pluripotent stem cells (hiPSCs), and their neuronal progeny, will play an important role in disease modeling, drug screening tests, central nervous system development studies, and may even become valuable for regenerative medicine treatments. Nonetheless, it is challenging to obtain homogeneous and synchronously differentiated NP populations from hiPSCs, and after neural commitment many pluripotent stem cells remain in the differentiated cultures. Here, we describe an efficient and simple protocol to differentiate hiPSC-derived NPs in 12 days, and we include a final purification stage where Tra-1-60+ pluripotent stem cells (PSCs) are removed using magnetic activated cell sorting (MACS), leaving the NP population nearly free of PSCs.

  4. ETOH inhibits embryonic neural stem/precursor cell proliferation via PLD signaling

    International Nuclear Information System (INIS)

    Fujita, Yuko; Hiroyama, Masami; Sanbe, Atsushi; Yamauchi, Junji; Murase, Shoko; Tanoue, Akito

    2008-01-01

    While a mother's excessive alcohol consumption during pregnancy is known to have adverse effects on fetal neural development, little is known about the underlying mechanism of these effects. In order to investigate these mechanisms, we investigated the toxic effect of ethanol (ETOH) on neural stem/precursor cell (NSC) proliferation. In cultures of NSCs, phospholipase D (PLD) is activated following stimulation with epidermal growth factor (EGF) and fibroblast growth factor 2 (FGF2). Exposure of NSCs to ETOH suppresses cell proliferation, while it has no effect on cell death. Phosphatidic acid (PA), which is a signaling messenger produced by PLD, reverses ETOH inhibition of NSC proliferation. Blocking the PLD signal by 1-butanol suppresses the proliferation. ETOH-induced suppression of NSC proliferation and the protective effect of PA for ETOH-induced suppression are mediated through extracellular signal-regulated kinase signaling. These results indicate that exposure to ETOH impairs NSC proliferation by altering the PLD signaling pathway

  5. Rejuvenation of MPTP-induced human neural precursor cell senescence by activating autophagy

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    Zhu, Liang [East Hospital, Tongji University School of Medicine, Shanghai (China); Dong, Chuanming [East Hospital, Tongji University School of Medicine, Shanghai (China); Department of Anatomy and Neurobiology, The Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong (China); Sun, Chenxi; Ma, Rongjie; Yang, Danjing [East Hospital, Tongji University School of Medicine, Shanghai (China); Zhu, Hongwen, E-mail: hongwen_zhu@hotmail.com [Tianjin Hospital, Tianjin Academy of Integrative Medicine, Tianjin (China); Xu, Jun, E-mail: xunymc2000@yahoo.com [East Hospital, Tongji University School of Medicine, Shanghai (China)

    2015-08-21

    Aging of neural stem cell, which can affect brain homeostasis, may be caused by many cellular mechanisms. Autophagy dysfunction was found in aged and neurodegenerative brains. However, little is known about the relationship between autophagy and human neural stem cell (hNSC) aging. The present study used 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) to treat neural precursor cells (NPCs) derived from human embryonic stem cell (hESC) line H9 and investigate related molecular mechanisms involved in this process. MPTP-treated NPCs were found to undergo premature senescence [determined by increased senescence-associated-β-galactosidase (SA-β-gal) activity, elevated intracellular reactive oxygen species level, and decreased proliferation] and were associated with impaired autophagy. Additionally, the cellular senescence phenotypes were manifested at the molecular level by a significant increase in p21 and p53 expression, a decrease in SOD2 expression, and a decrease in expression of some key autophagy-related genes such as Atg5, Atg7, Atg12, and Beclin 1. Furthermore, we found that the senescence-like phenotype of MPTP-treated hNPCs was rejuvenated through treatment with a well-known autophagy enhancer rapamycin, which was blocked by suppression of essential autophagy gene Beclin 1. Taken together, these findings reveal the critical role of autophagy in the process of hNSC aging, and this process can be reversed by activating autophagy. - Highlights: • We successfully establish hESC-derived neural precursor cells. • MPTP treatment induced senescence-like state in hESC-derived NPCs. • MPTP treatment induced impaired autophagy of hESC-derived NPCs. • MPTP-induced hESC-derived NPC senescence was rejuvenated by activating autophagy.

  6. Using superoxide dismutase/catalase mimetics to manipulate the redox environment of neural precursor cells

    International Nuclear Information System (INIS)

    Limoli, C. L.; Giedzinski, E.; Baure, J.; Doctrow, S. R.; Rola, R.; Fike, J. R.

    2006-01-01

    Past work has shown that neural precursor cells are predisposed to redox sensitive changes, and that oxidative stress plays a critical role in the acute and persistent changes that occur within the irradiated CNS. Irradiation leads to a marked rise in reactive oxygen species (ROS) that correlates with oxidative endpoints in vivo and reductions in neuro-genesis. To better understand the impact of oxidative stress on neural precursor cells, and to determine if radiation-induced oxidative damage and precursor cell loss after irradiation could be reduced, a series of antioxidant compounds (EUK-134, EUK-163, EUK-172, EUK-189) were tested, three of which possess both superoxide dismutase (SOD) and catalase activities and one (EUK-163) whose only significant activity is SOD. Our results show that these SOD/catalase mimetics apparently increase the oxidation of a ROS-sensitive fluorescent indicator dye, particularly after short (12 h) treatments, but that longer treatments (24 h) decrease oxidation attributable to radiation-induced ROS. Similarly, other studies found that cells incubated with CuZnSOD showed some increase in intracellular ROS levels. Subsequent data suggested that the dye-oxidising capabilities of the EUK compounds were linked to differences in their catalase activity and, most likely, their ability to catalyse per-oxidative pathways. In unirradiated mice, the EUK-134 analogue induced some decrease of proliferating precursor cells and immature neurons 48 h after radiation, an effect that may be attributable to cytotoxicity and/or inhibition of precursor proliferation. In irradiated mice, a single injection of EUK-134 was not found to be an effective radioprotector at acute times (48 h). The present results support continued development of our in vitro model as a tool for predicting certain in vivo responses, and suggest that in some biological systems the capability to scavenge superoxide but produce excess H 2 O 2 , as is known for CuZnSOD, may be

  7. Hippocalcin Is Required for Astrocytic Differentiation through Activation of Stat3 in Hippocampal Neural Precursor Cells.

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    Min-Jeong Kang

    2016-10-01

    Full Text Available Hippocalcin (Hpca is a neuronal calcium sensor protein expressed in the mammalian brain. However, its function in neural stem/precursor cells has not yet been studied. Here, we clarify the function of Hpca in astrocytic differentiation in hippocampal neural precursor cells (HNPCs. When we overexpressed Hpca in HNPCs in the presence or absence of bFGF, expression levels of nerve-growth factors such as neurotrophin-3 (NT-3, neurotrophin-4/5 (NT-4/5 and brain-derived neurotrophic factor (BDNF, together with the proneural basic helix loop helix (bHLH transcription factors neuroD and neurogenin 1 (ngn1, increased significantly. In addition, there was an increase in the number of cells expressing glial fibrillary acidic protein (GFAP, an astrocyte marker, and in dendrite outgrowth, indicating astrocytic differentiation of the HNPCs. Downregulation of Hpca by transfection with Hpca siRNA reduced expression of NT-3, NT-4/5, BDNF, neuroD and ngn1 as well as levels of GFAP protein. Furthermore, overexpression of Hpca increased the phosphorylation of STAT3 (Ser727, and this effect was abolished by treatment with a STAT3 inhibitor (S3I-201, suggesting that STAT3 (Ser727 activation is involved in Hpca-mediated astrocytic differentiation. As expected, treatment with Stat3 siRNA or STAT3 inhibitor caused a complete inhibition of astrogliogenesis induced by Hpca overexpression. Taken together, this is the first report to show that Hpca, acting through Stat3, has an important role in the expression of neurotrophins and proneural bHLH transcription factors, and that it is an essential regulator of astrocytic differentiation and dendrite outgrowth in HNPCs.

  8. Optimizing a multifunctional microsphere scaffold to improve neural precursor cell transplantation for traumatic brain injury repair.

    Science.gov (United States)

    Skop, Nolan B; Calderon, Frances; Cho, Cheul H; Gandhi, Chirag D; Levison, Steven W

    2016-10-01

    Tissue engineering using stem cells is widely used to repair damaged tissues in diverse biological systems; however, this approach has met with less success in regenerating the central nervous system (CNS). In this study we optimized and characterized the surface chemistry of chitosan-based scaffolds for CNS repair. To maintain radial glial cell (RGC) character of primitive neural precursors, fibronectin was adsorbed to chitosan. The chitosan was further modified by covalently linking heparin using genipin, which then served as a linker to immobilize fibroblast growth factor-2 (FGF-2), creating a multifunctional film. Fetal rat neural precursors plated onto this multifunctional film proliferated and remained multipotent for at least 3 days without providing soluble FGF-2. Moreover, they remained less mature and more highly proliferative than cells maintained on fibronectin-coated substrates in culture medium supplemented with soluble FGF-2. To create a vehicle for cell transplantation, a 3% chitosan solution was electrosprayed into a coagulation bath to generate microspheres (range 30-100 µm, mean 64 µm) that were subsequently modified. Radial glial cells seeded onto these multifunctional microspheres proliferated for at least 7 days in culture and the microspheres containing cells were small enough to be injected, using 23 Gauge Hamilton syringes, into the brains of adult rats that had previously sustained cortical contusion injuries. When analysed 3 days later, the transplanted RGCs were positive for the stem cell/progenitor marker Nestin. These results demonstrate that this multifunctional scaffold can be used as a cellular and growth factor delivery vehicle for the use in developing cell transplantation therapies for traumatic brain injuries. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.

  9. Restriction of neural precursor ability to respond to Nurr1 by early regional specification.

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    Chiara Soldati

    Full Text Available During neural development, spatially regulated expression of specific transcription factors is crucial for central nervous system (CNS regionalization, generation of neural precursors (NPs and subsequent differentiation of specific cell types within defined regions. A critical role in dopaminergic differentiation in the midbrain (MB has been assigned to the transcription factor Nurr1. Nurr1 controls the expression of key genes involved in dopamine (DA neurotransmission, e.g. tyrosine hydroxylase (TH and the DA transporter (DAT, and promotes the dopaminergic phenotype in embryonic stem cells. We investigated whether cells derived from different areas of the mouse CNS could be directed to differentiate into dopaminergic neurons in vitro by forced expression of the transcription factor Nurr1. We show that Nurr1 overexpression can promote dopaminergic cell fate specification only in NPs obtained from E13.5 ganglionic eminence (GE and MB, but not in NPs isolated from E13.5 cortex (CTX and spinal cord (SC or from the adult subventricular zone (SVZ. Confirming previous studies, we also show that Nurr1 overexpression can increase the generation of TH-positive neurons in mouse embryonic stem cells. These data show that Nurr1 ability to induce a dopaminergic phenotype becomes restricted during CNS development and is critically dependent on the region of NPs derivation. Our results suggest that the plasticity of NPs and their ability to activate a dopaminergic differentiation program in response to Nurr1 is regulated during early stages of neurogenesis, possibly through mechanisms controlling CNS regionalization.

  10. Neural precursor cells in the ischemic brain - integration, cellular crosstalk and consequences for stroke recovery

    Directory of Open Access Journals (Sweden)

    Dirk M. Hermann

    2014-09-01

    Full Text Available After an ischemic stroke, neural precursor cells (NPCs proliferate within major germinal niches of the brain. Endogenous NPCs subsequently migrate towards the ischemic lesion where they promote tissue remodelling and neural repair. Unfortunately, this restorative process is generally insufficient and thus unable to support a full recovery of lost neurological functions. Supported by solid experimental and preclinical data, the transplantation of exogenous NPCs has emerged as a potential tool for stroke treatment. Transplanted NPCs are thought to act mainly via trophic and immune modulatory effects, thereby complementing the restorative responses initially executed by the endogenous NPC population. Recent studies have attempted to elucidate how the therapeutic properties of transplanted NPCs vary depending on the route of transplantation. Systemic NPC delivery leads to potent immune modulatory actions, which prevent secondary neuronal degeneration, reduces glial scar formation, diminishes oxidative stress and stabilizes blood-brain barrier integrity. On the contrary, local stem cell delivery, allows for the accumulation of large numbers of transplanted NPCs in the brain, thus achieving high levels of locally available tissue trophic factors, which may better induce a strong endogenous NPC proliferative response.Herein we describe the diverse capabilities of exogenous (systemically vs locally transplanted NPCs in enhancing the endogenous neurogenic response after stroke, and how the route of transplantation may affect migration, survival, bystander effects and integration of the cellular graft. It is the authors’ claim that understanding these aspects will be of pivotal importance in discerning how transplanted NPCs exert their therapeutic effects in stroke.

  11. GDNF facilitates differentiation of the adult dentate gyrus-derived neural precursor cells into astrocytes via STAT3

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    Boku, Shuken, E-mail: shuboku@med.hokudai.ac.jp [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan); Nakagawa, Shin [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan); Takamura, Naoki [Pharmaceutical Laboratories, Dainippon Sumitomo Pharma Co. Ltd., Osaka (Japan); Kato, Akiko [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan); Takebayashi, Minoru [Department of Psychiatry, National Hospital Organization Kure Medical Center, Kure (Japan); Hisaoka-Nakashima, Kazue [Department of Pharmacology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima (Japan); Omiya, Yuki; Inoue, Takeshi; Kusumi, Ichiro [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan)

    2013-05-17

    Highlights: •GDNF has no effect on ADP proliferation and apoptosis. •GDNF increases ADP differentiation into astrocyte. •A specific inhibitor of STAT3 decreases the astrogliogenic effect of GDNF. •STAT3 knockdown by lentiviral shRNA vector also decreases the astrogliogenic effect of GDNF. •GDNF increases the phosphorylation of STAT3. -- Abstract: While the pro-neurogenic actions of antidepressants in the adult hippocampal dentate gyrus (DG) are thought to be one of the mechanisms through which antidepressants exert their therapeutic actions, antidepressants do not increase proliferation of neural precursor cells derived from the adult DG. Because previous studies showed that antidepressants increase the expression and secretion of glial cell line-derived neurotrophic factor (GDNF) in C6 glioma cells derived from rat astrocytes and GDNF increases neurogenesis in adult DG in vivo, we investigated the effects of GDNF on the proliferation, differentiation and apoptosis of cultured neural precursor cells derived from the adult DG. Data showed that GDNF facilitated the differentiation of neural precursor cells into astrocytes but had no effect on their proliferation or apoptosis. Moreover, GDNF increased the phosphorylation of STAT3, and both a specific inhibitor of STAT3 and lentiviral shRNA for STAT3 decreased their differentiation into astrocytes. Taken together, our findings suggest that GDNF facilitates astrogliogenesis from neural precursor cells in adult DG through activating STAT3 and that this action might indirectly affect neurogenesis.

  12. GDNF facilitates differentiation of the adult dentate gyrus-derived neural precursor cells into astrocytes via STAT3

    International Nuclear Information System (INIS)

    Boku, Shuken; Nakagawa, Shin; Takamura, Naoki; Kato, Akiko; Takebayashi, Minoru; Hisaoka-Nakashima, Kazue; Omiya, Yuki; Inoue, Takeshi; Kusumi, Ichiro

    2013-01-01

    Highlights: •GDNF has no effect on ADP proliferation and apoptosis. •GDNF increases ADP differentiation into astrocyte. •A specific inhibitor of STAT3 decreases the astrogliogenic effect of GDNF. •STAT3 knockdown by lentiviral shRNA vector also decreases the astrogliogenic effect of GDNF. •GDNF increases the phosphorylation of STAT3. -- Abstract: While the pro-neurogenic actions of antidepressants in the adult hippocampal dentate gyrus (DG) are thought to be one of the mechanisms through which antidepressants exert their therapeutic actions, antidepressants do not increase proliferation of neural precursor cells derived from the adult DG. Because previous studies showed that antidepressants increase the expression and secretion of glial cell line-derived neurotrophic factor (GDNF) in C6 glioma cells derived from rat astrocytes and GDNF increases neurogenesis in adult DG in vivo, we investigated the effects of GDNF on the proliferation, differentiation and apoptosis of cultured neural precursor cells derived from the adult DG. Data showed that GDNF facilitated the differentiation of neural precursor cells into astrocytes but had no effect on their proliferation or apoptosis. Moreover, GDNF increased the phosphorylation of STAT3, and both a specific inhibitor of STAT3 and lentiviral shRNA for STAT3 decreased their differentiation into astrocytes. Taken together, our findings suggest that GDNF facilitates astrogliogenesis from neural precursor cells in adult DG through activating STAT3 and that this action might indirectly affect neurogenesis

  13. Abnormal neural precursor cell regulation in the early postnatal Fragile X mouse hippocampus.

    Science.gov (United States)

    Sourial, Mary; Doering, Laurie C

    2017-07-01

    The regulation of neural precursor cells (NPCs) is indispensable for a properly functioning brain. Abnormalities in NPC proliferation, differentiation, survival, or integration have been linked to various neurological diseases including Fragile X syndrome. Yet, no studies have examined NPCs from the early postnatal Fragile X mouse hippocampus despite the importance of this developmental time point, which marks the highest expression level of FMRP, the protein missing in Fragile X, in the rodent hippocampus and is when hippocampal NPCs have migrated to the dentate gyrus (DG) to give rise to lifelong neurogenesis. In this study, we examined NPCs from the early postnatal hippocampus and DG of Fragile X mice (Fmr1-KO). Immunocytochemistry on neurospheres showed increased Nestin expression and decreased Ki67 expression, which collectively indicated aberrant NPC biology. Intriguingly, flow cytometric analysis of the expression of the antigens CD15, CD24, CD133, GLAST, and PSA-NCAM showed a decreased proportion of neural stem cells (GLAST + CD15 + CD133 + ) and an increased proportion of neuroblasts (PSA-NCAM + CD15 + ) in the DG of P7 Fmr1-KO mice. This was mirrored by lower expression levels of Nestin and the mitotic marker phospho-histone H3 in vivo in the P9 hippocampus, as well as a decreased proportion of cells in the G 2 /M phases of the P7 DG. Thus, the absence of FMRP leads to fewer actively cycling NPCs, coinciding with a decrease in neural stem cells and an increase in neuroblasts. Together, these results show the importance of FMRP in the developing hippocampal formation and suggest abnormalities in cell cycle regulation in Fragile X. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

  14. Magnetic excitations in ferromagnetic phase of MnP

    International Nuclear Information System (INIS)

    Yano, Shin-ichiro; Itoh, Shinichi; Yokoo, Tetsuya; Satoh, Setsuo; Kawana, Daichi; Kousaka, Yusuke; Akimitsu, Jun; Endoh, Yasuo

    2013-01-01

    Inelastic neutron scattering experiments were performed on an intermetallic compound, MnP. We used a newly developed High Resolution Chopper Spectrometer, HRC, for energy transfers E≤75meV, besides various triple axis spectrometers; LTAS for energy transfers E≤2meV, TOPAN for E≤7.5meV and TAS-1 for E≤35meV. Spin wave excitations were observed in the ferromagnetic phase of MnP in the entire Brillouin zone along the a ⁎ - and b ⁎ -axes. The zone boundary energies of spin waves were determined to be around 60 meV along the a ⁎ -axis and around 75 meV along the b ⁎ -axis, and the dispersion relations showed two branches for both axes. The observed dispersion relations of spin waves were well described by an isotropic Heisenberg interaction adding a single ion anisotropy with two sub-lattices. - Highlights: • Inelastic neutron scattering experiments were performed mainly using pulsed neutrons. • Spin waves were observed in the ferromagnetic phase of an intermetallic compound MnP. • The dispersion relations were determined entirely along the a ⁎ - and b ⁎ -axes. • We could describe the observed dispersion relations by a two sub-lattice model

  15. Hypoxia Epigenetically Confers Astrocytic Differentiation Potential on Human Pluripotent Cell-Derived Neural Precursor Cells

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    Tetsuro Yasui

    2017-06-01

    Full Text Available Human neural precursor cells (hNPCs derived from pluripotent stem cells display a high propensity for neuronal differentiation, but they require long-term culturing to differentiate efficiently into astrocytes. The mechanisms underlying this biased fate specification of hNPCs remain elusive. Here, we show that hypoxia confers astrocytic differentiation potential on hNPCs through epigenetic gene regulation, and that this was achieved by cooperation between hypoxia-inducible factor 1α and Notch signaling, accompanied by a reduction of DNA methylation level in the promoter region of a typical astrocyte-specific gene, Glial fibrillary acidic protein. Furthermore, we found that this hypoxic culture condition could be applied to rapid generation of astrocytes from Rett syndrome patient-derived hNPCs, and that these astrocytes impaired neuronal development. Thus, our findings shed further light on the molecular mechanisms regulating hNPC differentiation and provide attractive tools for the development of therapeutic strategies for treating astrocyte-mediated neurological disorders.

  16. Differential proliferation rhythm of neural progenitor and oligodendrocyte precursor cells in the young adult hippocampus.

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    Yoko Matsumoto

    Full Text Available Oligodendrocyte precursor cells (OPCs are a unique type of glial cells that function as oligodendrocyte progenitors while constantly proliferating in the normal condition from rodents to humans. However, the functional roles they play in the adult brain are largely unknown. In this study, we focus on the manner of OPC proliferation in the hippocampus of the young adult mice. Here we report that there are oscillatory dynamics in OPC proliferation that differ from neurogenesis in the subgranular zone (SGZ; the former showed S-phase and M-phase peaks in the resting and active periods, respectively, while the latter only exhibited M-phase peak in the active period. There is coincidence between different modes of proliferation and expression of cyclin proteins that are crucial for cell cycle; cyclin D1 is expressed in OPCs, while cyclin D2 is observed in neural stem cells. Similar to neurogenesis, the proliferation of hippocampal OPCs was enhanced by voluntary exercise that leads to an increase in neuronal activity in the hippocampus. These data suggest an intriguing control of OPC proliferation in the hippocampus.

  17. Human Neural Precursor Cells Promote Neurologic Recovery in a Viral Model of Multiple Sclerosis

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    Lu Chen

    2014-06-01

    Full Text Available Using a viral model of the demyelinating disease multiple sclerosis (MS, we show that intraspinal transplantation of human embryonic stem cell-derived neural precursor cells (hNPCs results in sustained clinical recovery, although hNPCs were not detectable beyond day 8 posttransplantation. Improved motor skills were associated with a reduction in neuroinflammation, decreased demyelination, and enhanced remyelination. Evidence indicates that the reduced neuroinflammation is correlated with an increased number of CD4+CD25+FOXP3+ regulatory T cells (Tregs within the spinal cords. Coculture of hNPCs with activated T cells resulted in reduced T cell proliferation and increased Treg numbers. The hNPCs acted, in part, through secretion of TGF-β1 and TGF-β2. These findings indicate that the transient presence of hNPCs transplanted in an animal model of MS has powerful immunomodulatory effects and mediates recovery. Further investigation of the restorative effects of hNPC transplantation may aid in the development of clinically relevant MS treatments.

  18. Neutron scattering evidence on Lifshitz behavior in MnP

    International Nuclear Information System (INIS)

    Moon, R.M.; Cable, J.W.; Shapira, Y.

    1980-09-01

    The variation of q→ in the fan phase of MnP was measured in order to test whether the para-ferro-fan triple point is a Lifshitz point. Along the para-fan phase boundary, q→ continuously decreases as the triple point is approached, extrapolating to zero at a temperature in good agreement with other measurements of the triple point. The temperature dependence of q→ along this phase boundary is in approximate agreement with theoretical expectations for Lifshitz point behavior. These data support the conclusion that the triple point is a Lifshitz point

  19. Tricyclic antidepressant amitriptyline indirectly increases the proliferation of adult dentate gyrus-derived neural precursors: an involvement of astrocytes.

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    Shuken Boku

    Full Text Available Antidepressants increase the proliferation of neural precursors in adult dentate gyrus (DG, which is considered to be involved in the therapeutic action of antidepressants. However, the mechanism underlying it remains unclear. By using cultured adult rat DG-derived neural precursors (ADP, we have already shown that antidepressants have no direct effects on ADP. Therefore, antidepressants may increase the proliferation of neural precursors in adult DG via unknown indirect mechanism. We have also shown that amitriptyline (AMI, a tricyclic antidepressant, induces the expressions of GDNF, BDNF, FGF2 and VEGF, common neurogenic factors, in primary cultured astrocytes (PCA. These suggest that AMI-induced factors in astrocytes may increase the proliferation of neural precursors in adult DG. To test this hypothesis, we examined the effects of AMI-induced factors and conditioned medium (CM from PCA treated with AMI on ADP proliferation. The effects of CM and factors on ADP proliferation were examined with BrdU immunocytochemistry. AMI had no effect on ADP proliferation, but AMI-treated CM increased it. The receptors of GDNF, BDNF and FGF2, but not VEGF, were expressed in ADP. FGF2 significantly increased ADP proliferation, but not BDNF and GDNF. In addition, both of a specific inhibitor of FGF receptors and anti-FGF2 antibody significantly counteracted the increasing effect of CM on ADP proliferation. In addition, FGF2 in brain is mainly derived from astrocytes that are key components of the neurogenic niches in adult DG. These suggest that AMI may increase ADP proliferation indirectly via PCA and that FGF2 may a potential candidate to mediate such an indirect effect of AMI on ADP proliferation via astrocytes.

  20. GDNF/GFRα1 Complex Abrogates Self-Renewing Activity of Cortical Neural Precursors Inducing Their Differentiation

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    Antonela Bonafina

    2018-03-01

    Full Text Available Summary: The balance between factors leading to proliferation and differentiation of cortical neural precursors (CNPs determines the correct cortical development. In this work, we show that GDNF and its receptor GFRα1 are expressed in the neocortex during the period of cortical neurogenesis. We show that the GDNF/GFRα1 complex inhibits the self-renewal capacity of mouse CNP cells induced by fibroblast growth factor 2 (FGF2, promoting neuronal differentiation. While GDNF leads to decreased proliferation of cultured cortical precursor cells, ablation of GFRα1 in glutamatergic cortical precursors enhances its proliferation. We show that GDNF treatment of CNPs promoted morphological differentiation even in the presence of the self-renewal-promoting factor, FGF2. Analysis of GFRα1-deficient mice shows an increase in the number of cycling cells during cortical development and a reduction in dendrite development of cortical GFRα1-expressing neurons. Together, these results indicate that GDNF/GFRα1 signaling plays an essential role in regulating the proliferative condition and the differentiation of cortical progenitors. : In this article, Ledda and colleagues show that GDNF acting through its receptor GFRα1 plays a critical role in the maturation of cortical progenitors by counteracting FGF2 self-renewal activity on neural stem cells and promoting neuronal differentiation. Keywords: GDNF, GFRα1, cortical precursors, proliferation, postmitotic neurons, neuronal differentiation

  1. Transplantation of Neural Precursor Cells Attenuates Chronic Immune Environment in Cervical Spinal Cord Injury

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    Lennart Riemann

    2018-06-01

    Full Text Available Inflammation after traumatic spinal cord injury (SCI is non-resolving and thus still present in chronic injury stages. It plays a key role in the pathophysiology of SCI and has been associated with further neurodegeneration and development of neuropathic pain. Neural precursor cells (NPCs have been shown to reduce the acute and sub-acute inflammatory response after SCI. In the present study, we examined effects of NPC transplantation on the immune environment in chronic stages of SCI. SCI was induced in rats by clip-compression of the cervical spinal cord at the level C6-C7. NPCs were transplanted 10 days post-injury. The functional outcome was assessed weekly for 8 weeks using the Basso, Beattie, and Bresnahan scale, the CatWalk system, and the grid walk test. Afterwards, the rats were sacrificed, and spinal cord sections were examined for M1/M2 macrophages, T lymphocytes, astrogliosis, and apoptosis using immunofluorescence staining. Rats treated with NPCs had compared to the control group significantly fewer pro-inflammatory M1 macrophages and reduced immunodensity for inducible nitric oxide synthase (iNOS, their marker enzyme. Anti-inflammatory M2 macrophages were rarely present 8 weeks after the SCI. In this model, the sub-acute transplantation of NPCs did not support survival and proliferation of M2 macrophages. Post-traumatic apoptosis, however, was significantly reduced in the NPC group, which might be explained by the altered microenvironment following NPC transplantation. Corresponding to these findings, reactive astrogliosis was significantly reduced in NPC-transplanted animals. Furthermore, we could observe a trend toward smaller cavity sizes and functional improvement following NPC transplantation. Our data suggest that transplantation of NPCs following SCI might attenuate inflammation even in chronic injury stages. This might prevent further neurodegeneration and could also set a stage for improved neuroregeneration after SCI.

  2. Impaired neurogenesis, learning and memory and low seizure threshold associated with loss of neural precursor cell survivin

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    Eisch Amelia

    2010-01-01

    Full Text Available Abstract Background Survivin is a unique member of the inhibitor of apoptosis protein (IAP family in that it exhibits antiapoptotic properties and also promotes the cell cycle and mediates mitosis as a chromosome passenger protein. Survivin is highly expressed in neural precursor cells in the brain, yet its function there has not been elucidated. Results To examine the role of neural precursor cell survivin, we first showed that survivin is normally expressed in periventricular neurogenic regions in the embryo, becoming restricted postnatally to proliferating and migrating NPCs in the key neurogenic sites, the subventricular zone (SVZ and the subgranular zone (SGZ. We then used a conditional gene inactivation strategy to delete the survivin gene prenatally in those neurogenic regions. Lack of embryonic NPC survivin results in viable, fertile mice (SurvivinCamcre with reduced numbers of SVZ NPCs, absent rostral migratory stream, and olfactory bulb hypoplasia. The phenotype can be partially rescued, as intracerebroventricular gene delivery of survivin during embryonic development increases olfactory bulb neurogenesis, detected postnatally. SurvivinCamcre brains have fewer cortical inhibitory interneurons, contributing to enhanced sensitivity to seizures, and profound deficits in memory and learning. Conclusions The findings highlight the critical role that survivin plays during neural development, deficiencies of which dramatically impact on postnatal neural function.

  3. Ca(2+) coding and decoding strategies for the specification of neural and renal precursor cells during development.

    Science.gov (United States)

    Moreau, Marc; Néant, Isabelle; Webb, Sarah E; Miller, Andrew L; Riou, Jean-François; Leclerc, Catherine

    2016-03-01

    During embryogenesis, a rise in intracellular Ca(2+) is known to be a widespread trigger for directing stem cells towards a specific tissue fate, but the precise Ca(2+) signalling mechanisms involved in achieving these pleiotropic effects are still poorly understood. In this review, we compare the Ca(2+) signalling events that appear to be one of the first steps in initiating and regulating both neural determination (neural induction) and kidney development (nephrogenesis). We have highlighted the necessary and sufficient role played by Ca(2+) influx and by Ca(2+) transients in the determination and differentiation of pools of neural or renal precursors. We have identified new Ca(2+) target genes involved in neural induction and we showed that the same Ca(2+) early target genes studied are not restricted to neural tissue but are also present in other tissues, principally in the pronephros. In this review, we also described a mechanism whereby the transcriptional control of gene expression during neurogenesis and nephrogenesis might be directly controlled by Ca(2+) signalling. This mechanism involves members of the Kcnip family such that a change in their binding properties to specific DNA sites is a result of Ca(2+) binding to EF-hand motifs. The different functions of Ca(2+) signalling during these two events illustrate the versatility of Ca(2+) as a second messenger. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Beneficial effect of human induced pluripotent stem cell-derived neural precursors in spinal cord injury repair

    Czech Academy of Sciences Publication Activity Database

    Romanyuk, Nataliya; Amemori, Takashi; Turnovcová, Karolína; Procházka, Pavel; Onteniente, B.; Syková, Eva; Jendelová, Pavla

    2015-01-01

    Roč. 24, č. 9 (2015), s. 1781-1797 ISSN 0963-6897 R&D Projects: GA MŠk LH12024; GA ČR(CZ) GA13-00939S; GA ČR(CZ) GBP304/12/G069; GA MŠk(CZ) ED1.1.00/02.0109; GA MŠk(CZ) LO1309 Institutional support: RVO:68378041 Keywords : human induced pluripotent stem cells * neural precursors * spinal cord injury Subject RIV: FH - Neurology Impact factor: 3.427, year: 2015

  5. The effect of magnetic nanoparticles on neuronal differentiation of induced pluripotent stem cell-derived neural precursors

    Czech Academy of Sciences Publication Activity Database

    Jiráková, Klára; Šeneklová, Monika; Jirák, D.; Turnovcová, Karolína; Vosmanská, M.; Babič, Michal; Horák, Daniel; Veverka, Pavel; Jendelová, Pavla

    2016-01-01

    Roč. 11, č. 2016 (2016), s. 6267-6281 E-ISSN 1178-2013 R&D Projects: GA MŠk(CZ) LQ1604; GA MŠk(CZ) ED1.1.00/02.0109; GA MŠk(CZ) 7F14057 Institutional support: RVO:68378041 ; RVO:61389013 ; RVO:68378271 Keywords : neural precursors * magnetic resonance imaging * cell differentiation Subject RIV: FH - Neurology; EB - Genetics ; Molecular Biology (FGU-C); CD - Macromolecular Chemistry (UMCH-V) Impact factor: 4.300, year: 2016

  6. Differentiation of neurons from neural precursors generated in floating spheres from embryonic stem cells

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    Forrester Jeff

    2009-09-01

    Full Text Available Abstract Background Neural differentiation of embryonic stem (ES cells is usually achieved by induction of ectoderm in embryoid bodies followed by the enrichment of neuronal progenitors using a variety of factors. Obtaining reproducible percentages of neural cells is difficult and the methods are time consuming. Results Neural progenitors were produced from murine ES cells by a combination of nonadherent conditions and serum starvation. Conversion to neural progenitors was accompanied by downregulation of Oct4 and NANOG and increased expression of nestin. ES cells containing a GFP gene under the control of the Sox1 regulatory regions became fluorescent upon differentiation to neural progenitors, and ES cells with a tau-GFP fusion protein became fluorescent upon further differentiation to neurons. Neurons produced from these cells upregulated mature neuronal markers, or differentiated to glial and oligodendrocyte fates. The neurons gave rise to action potentials that could be recorded after application of fixed currents. Conclusion Neural progenitors were produced from murine ES cells by a novel method that induced neuroectoderm cells by a combination of nonadherent conditions and serum starvation, in contrast to the embryoid body method in which neuroectoderm cells must be selected after formation of all three germ layers.

  7. Cell death in neural precursor cells and neurons before neurite formation prevents the emergence of abnormal neural structures in the Drosophila optic lobe.

    Science.gov (United States)

    Hara, Yusuke; Sudo, Tatsuya; Togane, Yu; Akagawa, Hiromi; Tsujimura, Hidenobu

    2018-04-01

    Programmed cell death is a conserved strategy for neural development both in vertebrates and invertebrates and is recognized at various developmental stages in the brain from neurogenesis to adulthood. To understand the development of the central nervous system, it is essential to reveal not only molecular mechanisms but also the role of neural cell death (Pinto-Teixeira et al., 2016). To understand the role of cell death in neural development, we investigated the effect of inhibition of cell death on optic lobe development. Our data demonstrate that, in the optic lobe of Drosophila, cell death occurs in neural precursor cells and neurons before neurite formation and functions to prevent various developmental abnormalities. When neuronal cell death was inhibited by an effector caspase inhibitor, p35, multiple abnormal neuropil structures arose during optic lobe development-e.g., enlarged or fused neuropils, misrouted neurons and abnormal neurite lumps. Inhibition of cell death also induced morphogenetic defects in the lamina and medulla development-e.g., failures in the separation of the lamina and medulla cortices and the medulla rotation. These defects were reproduced in the mutant of an initiator caspase, dronc. If cell death was a mechanism for removing the abnormal neuropil structures, we would also expect to observe them in mutants defective for corpse clearance. However, they were not observed in these mutants. When dead cell-membranes were visualized with Apoliner, they were observed only in cortices and not in neuropils. These results suggest that the cell death occurs before mature neurite formation. Moreover, we found that inhibition of cell death induced ectopic neuroepithelial cells, neuroblasts and ganglion mother cells in late pupal stages, at sites where the outer and inner proliferation centers were located at earlier developmental stages. Caspase-3 activation was observed in the neuroepithelial cells and neuroblasts in the proliferation centers

  8. Pulsed DC Electric Field-Induced Differentiation of Cortical Neural Precursor Cells.

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    Hui-Fang Chang

    Full Text Available We report the differentiation of neural stem and progenitor cells solely induced by direct current (DC pulses stimulation. Neural stem and progenitor cells in the adult mammalian brain are promising candidates for the development of therapeutic neuroregeneration strategies. The differentiation of neural stem and progenitor cells depends on various in vivo environmental factors, such as nerve growth factor and endogenous EF. In this study, we demonstrated that the morphologic and phenotypic changes of mouse neural stem and progenitor cells (mNPCs could be induced solely by exposure to square-wave DC pulses (magnitude 300 mV/mm at frequency of 100-Hz. The DC pulse stimulation was conducted for 48 h, and the morphologic changes of mNPCs were monitored continuously. The length of primary processes and the amount of branching significantly increased after stimulation by DC pulses for 48 h. After DC pulse treatment, the mNPCs differentiated into neurons, astrocytes, and oligodendrocytes simultaneously in stem cell maintenance medium. Our results suggest that simple DC pulse treatment could control the fate of NPCs. With further studies, DC pulses may be applied to manipulate NPC differentiation and may be used for the development of therapeutic strategies that employ NPCs to treat nervous system disorders.

  9. Pulsed DC Electric Field-Induced Differentiation of Cortical Neural Precursor Cells.

    Science.gov (United States)

    Chang, Hui-Fang; Lee, Ying-Shan; Tang, Tang K; Cheng, Ji-Yen

    2016-01-01

    We report the differentiation of neural stem and progenitor cells solely induced by direct current (DC) pulses stimulation. Neural stem and progenitor cells in the adult mammalian brain are promising candidates for the development of therapeutic neuroregeneration strategies. The differentiation of neural stem and progenitor cells depends on various in vivo environmental factors, such as nerve growth factor and endogenous EF. In this study, we demonstrated that the morphologic and phenotypic changes of mouse neural stem and progenitor cells (mNPCs) could be induced solely by exposure to square-wave DC pulses (magnitude 300 mV/mm at frequency of 100-Hz). The DC pulse stimulation was conducted for 48 h, and the morphologic changes of mNPCs were monitored continuously. The length of primary processes and the amount of branching significantly increased after stimulation by DC pulses for 48 h. After DC pulse treatment, the mNPCs differentiated into neurons, astrocytes, and oligodendrocytes simultaneously in stem cell maintenance medium. Our results suggest that simple DC pulse treatment could control the fate of NPCs. With further studies, DC pulses may be applied to manipulate NPC differentiation and may be used for the development of therapeutic strategies that employ NPCs to treat nervous system disorders.

  10. In vitro culture and characterization of enteric neural precursor cells from human gut biopsy specimens using polymer scaffold.

    Science.gov (United States)

    Krishnamohan, Janardhanam; Senthilnathan, Venugopal S; Vaikundaraman, Tirunelveli Muthiah; Srinivasan, Thangavelu; Balamurugan, Madasamy; Iwasaki, Masaru; Preethy, Senthilkumar; Abraham, Samuel Jk

    2013-08-01

    In vitro expansion and characterization of neural precursor cells from human gut biopsy specimens with or without Hirschsprung's disease using a novel thermoreversible gelation polymer (TGP) is reported aiming at a possible future treatment. Gut biopsy samples were obtained from five patients undergoing gut resection for Hirschsprung's disease (n = 1) or gastrointestinal disorders (n = 4). Cells isolated from the smooth muscle layer and the myenteric plexus were cultured in two groups for 18 to 28 days; Group I: conventional culture as earlier reported and Group II: using TGP scaffold. Neurosphere like bodies (NLBs) were observed in the cultures between 8th to 12th day and H & E staining was positive for neural cells in both groups including aganglionic gut portion from the Hirschsprung's disease patient. Immunohistochemistry using S-100 and neuron specific enolase (NSE) was positive in both groups but the TGP group (Group II) showed more number of cells with intense cytoplasmic granular positivity for both NSE and S-100 compared to Group I. TGP supports the in vitro expansion of human gut derived neuronal cells with seemingly better quality NLBs. Animal Studies can be tried to validate their functional outcome by transplanting the NLBs with TGP scaffolds to see whether this can enhance the outcome of cell based therapies for Hirschsprung's disease.

  11. Activating receptor NKG2D targets RAE-1-expressing allogeneic neural precursor cells in a viral model of multiple sclerosis.

    Science.gov (United States)

    Weinger, Jason G; Plaisted, Warren C; Maciejewski, Sonia M; Lanier, Lewis L; Walsh, Craig M; Lane, Thomas E

    2014-10-01

    Transplantation of major histocompatibility complex-mismatched mouse neural precursor cells (NPCs) into mice persistently infected with the neurotropic JHM strain of mouse hepatitis virus (JHMV) results in rapid rejection that is mediated, in part, by T cells. However, the contribution of the innate immune response to allograft rejection in a model of viral-induced neurological disease has not been well defined. Herein, we demonstrate that the natural killer (NK) cell-expressing-activating receptor NKG2D participates in transplanted allogeneic NPC rejection in mice persistently infected with JHMV. Cultured NPCs derived from C57BL/6 (H-2(b) ) mice express the NKG2D ligand retinoic acid early precursor transcript (RAE)-1 but expression was dramatically reduced upon differentiation into either glia or neurons. RAE-1(+) NPCs were susceptible to NK cell-mediated killing whereas RAE-1(-) cells were resistant to lysis. Transplantation of C57BL/6-derived NPCs into JHMV-infected BALB/c (H-2(d) ) mice resulted in infiltration of NKG2D(+) CD49b(+) NK cells and treatment with blocking antibody specific for NKG2D increased survival of allogeneic NPCs. Furthermore, transplantation of differentiated RAE-1(-) allogeneic NPCs into JHMV-infected BALB/c mice resulted in enhanced survival, highlighting a role for the NKG2D/RAE-1 signaling axis in allograft rejection. We also demonstrate that transplantation of allogeneic NPCs into JHMV-infected mice resulted in infection of the transplanted cells suggesting that these cells may be targets for infection. Viral infection of cultured cells increased RAE-1 expression, resulting in enhanced NK cell-mediated killing through NKG2D recognition. Collectively, these results show that in a viral-induced demyelination model, NK cells contribute to rejection of allogeneic NPCs through an NKG2D signaling pathway. © 2014 AlphaMed Press.

  12. Signaling through three chemokine receptors triggers the migration of transplanted neural precursor cells in a model of multiple sclerosis.

    Science.gov (United States)

    Cohen, Mikhal E; Fainstein, Nina; Lavon, Iris; Ben-Hur, Tamir

    2014-09-01

    Multiple sclerosis (MS) is a multifocal disease, and precursor cells need to migrate into the multiple lesions in order to exert their therapeutic effects. Therefore, cell migration is a crucial element in regenerative processes in MS, dictating the route of delivery, when cell transplantation is considered. We have previously shown that inflammation triggers migration of multi-potential neural precursor cells (NPCs) into the white matter of experimental autoimmune encephalomyelitis (EAE) rodents, a widely used model of MS. Here we investigated the molecular basis of this attraction. NPCs were grown from E13 embryonic mouse brains and transplanted into the lateral cerebral ventricles of EAE mice. Transplanted NPC migration was directed by three tissue-derived chemokines. Stromal cell-derived factor-1α, monocyte chemo-attractant protein-1 and hepatocyte growth factor were expressed in the EAE brain and specifically in microglia and astrocytes. Their cognate receptors, CXCR4, CCR2 or c-Met were constitutively expressed on NPCs. Selective blockage of CXCR4, CCR2 or c-Met partially inhibited NPC migration in EAE brains. Blocking all three receptors had an additive effect and resulted in profound inhibition of NPC migration, as compared to extensive migration of control NPCs. The inflammation-triggered NPC migration into white matter tracts was dependent on a motile NPC phenotype. Specifically, depriving NPCs from epidermal growth factor (EGF) prevented the induction of glial commitment and a motile phenotype (as indicated by an in vitro motility assay), hampering their response to neuroinflammation. In conclusion, signaling via three chemokine systems accounts for most of the inflammation-induced, tissue-derived attraction of transplanted NPCs into white matter tracts during EAE. Copyright © 2014. Published by Elsevier B.V.

  13. Functional cross-talk between the cellular prion protein and the neural cell adhesion molecule is critical for neuronal differentiation of neural stem/precursor cells.

    Science.gov (United States)

    Prodromidou, Kanella; Papastefanaki, Florentia; Sklaviadis, Theodoros; Matsas, Rebecca

    2014-06-01

    Cellular prion protein (PrP) is prominently expressed in brain, in differentiated neurons but also in neural stem/precursor cells (NPCs). The misfolding of PrP is a central event in prion diseases, yet the physiological function of PrP is insufficiently understood. Although PrP has been reported to associate with the neural cell adhesion molecule (NCAM), the consequences of concerted PrP-NCAM action in NPC physiology are unknown. Here, we generated NPCs from the subventricular zone (SVZ) of postnatal day 5 wild-type and PrP null (-/-) mice and observed that PrP is essential for proper NPC proliferation and neuronal differentiation. Moreover, we found that PrP is required for the NPC response to NCAM-induced neuronal differentiation. In the absence of PrP, NCAM not only fails to promote neuronal differentiation but also induces an accumulation of doublecortin-positive neuronal progenitors at the proliferation stage. In agreement, we noted an increase in cycling neuronal progenitors in the SVZ of PrP-/- mice compared with PrP+/+ mice, as evidenced by double labeling for the proliferation marker Ki67 and doublecortin as well as by 5-bromo-2'-deoxyuridine incorporation experiments. Additionally, fewer newly born neurons were detected in the rostral migratory stream of PrP-/- mice. Analysis of the migration of SVZ cells in microexplant cultures from wild-type and PrP-/- mice revealed no differences between genotypes or a role for NCAM in this process. Our data demonstrate that PrP plays a critical role in neuronal differentiation of NPCs and suggest that this function is, at least in part, NCAM-dependent. © 2014 AlphaMed Press.

  14. Regulatory Role of Redox Balance in Determination of Neural Precursor Cell Fate

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    Mohamed Ariff Iqbal

    2017-01-01

    Full Text Available In 1990s, reports of discovery of a small group of cells capable of proliferation and contribution to formation of new neurons in the central nervous system (CNS reversed a century-old concept on lack of neurogenesis in the adult mammalian brain. These cells are found in all stages of human life and contribute to normal cellular turnover of the CNS. Therefore, the identity of regulating factors that affect their proliferation and differentiation is a highly noteworthy issue for basic scientists and their clinician counterparts for therapeutic purposes. The cues for such control are embedded in developmental and environmental signaling through a highly regulated tempo-spatial expression of specific transcription factors. Novel findings indicate the importance of reactive oxygen species (ROS in the regulation of this signaling system. The elusive nature of ROS signaling in many vital processes from cell proliferation to cell death creates a complex literature in this field. Here, we discuss the emerging thoughts on the importance of redox regulation of proliferation and maintenance in mammalian neural stem and progenitor cells under physiological and pathological conditions. The current knowledge on ROS-mediated changes in redox-sensitive proteins that govern the molecular mechanisms in proliferation and differentiation of these cells is reviewed.

  15. Neuroprotective effect of transplanted human embryonic stem cell-derived neural precursors in an animal model of multiple sclerosis.

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    Michal Aharonowiz

    Full Text Available BACKGROUND: Multiple sclerosis (MS is an immune mediated demyelinating disease of the central nervous system (CNS. A potential new therapeutic approach for MS is cell transplantation which may promote remyelination and suppress the inflammatory process. METHODS: We transplanted human embryonic stem cells (hESC-derived early multipotent neural precursors (NPs into the brain ventricles of mice induced with experimental autoimmune encephalomyelitis (EAE, the animal model of MS. We studied the effect of the transplanted NPs on the functional and pathological manifestations of the disease. RESULTS: Transplanted hESC-derived NPs significantly reduced the clinical signs of EAE. Histological examination showed migration of the transplanted NPs to the host white matter, however, differentiation to mature oligodendrocytes and remyelination were negligible. Time course analysis of the evolution and progression of CNS inflammation and tissue injury showed an attenuation of the inflammatory process in transplanted animals, which was correlated with the reduction of both axonal damage and demyelination. Co-culture experiments showed that hESC-derived NPs inhibited the activation and proliferation of lymph node-derived T cells in response to nonspecific polyclonal stimuli. CONCLUSIONS: The therapeutic effect of transplantation was not related to graft or host remyelination but was mediated by an immunosuppressive neuroprotective mechanism. The attenuation of EAE by hESC-derived NPs, demonstrated here, may serve as the first step towards further developments of hESC for cell therapy in MS.

  16. Tumour necrosis factor-alpha impairs neuronal differentiation but not proliferation of hippocampal neural precursor cells: Role of Hes1.

    Science.gov (United States)

    Keohane, Aoife; Ryan, Sinead; Maloney, Eimer; Sullivan, Aideen M; Nolan, Yvonne M

    2010-01-01

    Tumour necrosis factor-alpha (TNFalpha) is a pro-inflammatory cytokine, which influences neuronal survival and function yet there is limited information available on its effects on hippocampal neural precursor cells (NPCs). We show that TNFalpha treatment during proliferation had no effect on the percentage of proliferating cells prepared from embryonic rat hippocampal neurosphere cultures, nor did it affect cell fate towards either an astrocytic or neuronal lineage when cells were then allowed to differentiate. However, when cells were differentiated in the presence of TNFalpha, significantly reduced percentages of newly born and post-mitotic neurons, significantly increased percentages of astrocytes and increased expression of TNFalpha receptors, TNF-R1 and TNF-R2, as well as expression of the anti-neurogenic Hes1 gene, were observed. These data indicate that exposure of hippocampal NPCs to TNFalpha when they are undergoing differentiation but not proliferation has a detrimental effect on their neuronal lineage fate, which may be mediated through increased expression of Hes1. Copyright 2009 Elsevier Inc. All rights reserved.

  17. Chondroitin sulfate proteoglycans regulate the growth, differentiation and migration of multipotent neural precursor cells through the integrin signaling pathway

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    Lü He-Zuo

    2009-10-01

    Full Text Available Abstract Background Neural precursor cells (NPCs are defined by their ability to proliferate, self-renew, and retain the potential to differentiate into neurons and glia. Deciphering the factors that regulate their behaviors will greatly aid in their use as potential therapeutic agents or targets. Chondroitin sulfate proteoglycans (CSPGs are prominent components of the extracellular matrix (ECM in the central nervous system (CNS and are assumed to play important roles in controlling neuronal differentiation and development. Results In the present study, we demonstrated that CSPGs were constitutively expressed on the NPCs isolated from the E16 rat embryonic brain. When chondroitinase ABC was used to abolish the function of endogenous CSPGs on NPCs, it induced a series of biological responses including the proliferation, differentiation and migration of NPCs, indicating that CSPGs may play a critical role in NPC development and differentiation. Finally, we provided evidence suggesting that integrin signaling pathway may be involved in the effects of CSPGs on NPCs. Conclusion The present study investigating the influence and mechanisms of CSPGs on the differentiation and migration of NPCs should help us to understand the basic biology of NPCs during CNS development and provide new insights into developing new strategies for the treatment of the neurological disorders in the CNS.

  18. Effective long-term immunosuppression in rats by subcutaneously implanted sustained-release tacrolimus pellet: Effect on spinally grafted human neural precursor survival

    Czech Academy of Sciences Publication Activity Database

    Ševc, J.; Goldberg, D.; van Gorp, S.; Leerink, M.; Juhás, Štefan; Juhásová, Jana; Marsala, S.; Hruška-Plocháň, Marian; Hefferan, M. P.; Motlík, Jan; Rypáček, František; Machová, Luďka; Kakinohana, O.; Santucci, C.; Johe, K.; Lukáčová, N.; Yamada, K.; Bui, J. D.; Marsala, M.

    2013-01-01

    Roč. 248, October (2013), s. 85-99 ISSN 0014-4886 R&D Projects: GA TA ČR TA01011466; GA MŠk ED2.1.00/03.0124 Institutional support: RVO:67985904 ; RVO:61389013 Keywords : immunosuppression * xenograft * human neural precursors Subject RIV: FH - Neurology; CD - Macromolecular Chemistry (UMCH-V) Impact factor: 4.617, year: 2013

  19. A Rhodium(III) Complex as an Inhibitor of Neural Precursor Cell Expressed, Developmentally Down-Regulated 8-Activating Enzyme with in Vivo Activity against Inflammatory Bowel Disease.

    Science.gov (United States)

    Zhong, Hai-Jing; Wang, Wanhe; Kang, Tian-Shu; Yan, Hui; Yang, Yali; Xu, Lipeng; Wang, Yuqiang; Ma, Dik-Lung; Leung, Chung-Hang

    2017-01-12

    We report herein the identification of the rhodium(III) complex [Rh(phq) 2 (MOPIP)] + (1) as a potent and selective ATP-competitive neural precursor cell expressed, developmentally down-regulated 8 (NEDD8)-activating enzyme (NAE) inhibitor. Structure-activity relationship analysis indicated that the overall organometallic design of complex 1 was important for anti-inflammatory activity. Complex 1 showed promising anti-inflammatory activity in vivo for the potential treatment of inflammatory bowel disease.

  20. Time Course of Spinal Doublecortin Expression in Developing Rat and Porcine Spinal Cord: Implication in In Vivo Neural Precursor Grafting Studies

    Czech Academy of Sciences Publication Activity Database

    Juhásová, Jana; Juhás, Štefan; Hruška-Plocháň, M.; Doležalová, D.; Holubová, Monika; Strnádel, Ján; Marsala, S.; Motlík, Jan; Marsala, M.

    2015-01-01

    Roč. 35, č. 1 (2015), s. 57-70 ISSN 0272-4340 R&D Projects: GA TA ČR(CZ) TA01011466; GA MŠk ED2.1.00/03.0124 Institutional support: RVO:67985904 Keywords : doublecortin * spinal cord development * spinal neural precursor grafting * minipig * rat * GFAP Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.328, year: 2015

  1. Cyclosporin A-Mediated Activation of Endogenous Neural Precursor Cells Promotes Cognitive Recovery in a Mouse Model of Stroke

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    Labeeba Nusrat

    2018-04-01

    Full Text Available Cognitive dysfunction following stroke significantly impacts quality of life and functional independance; yet, despite the prevalence and negative impact of cognitive deficits, post-stroke interventions almost exclusively target motor impairments. As a result, current treatment options are limited in their ability to promote post-stroke cognitive recovery. Cyclosporin A (CsA has been previously shown to improve post-stroke functional recovery of sensorimotor deficits. Interestingly, CsA is a commonly used immunosuppressant and also acts directly on endogenous neural precursor cells (NPCs in the neurogenic regions of the brain (the periventricular region and the dentate gyrus. The immunosuppressive and NPC activation effects are mediated by calcineurin-dependent and calcineurin-independent pathways, respectively. To develop a cognitive stroke model, focal bilateral lesions were induced in the medial prefrontal cortex (mPFC of adult mice using endothelin-1. First, we characterized this stroke model in the acute and chronic phase, using problem-solving and memory-based cognitive tests. mPFC stroke resulted in early and persistent deficits in short-term memory, problem-solving and behavioral flexibility, without affecting anxiety. Second, we investigated the effects of acute and chronic CsA treatment on NPC activation, neuroprotection, and tissue damage. Acute CsA administration post-stroke increased the size of the NPC pool. There was no effect on neurodegeneration or lesion volume. Lastly, we looked at the effects of chronic CsA treatment on cognitive recovery. Long-term CsA administration promoted NPC migration toward the lesion site and rescued cognitive deficits to control levels. This study demonstrates that CsA treatment activates the NPC population, promotes migration of NPCs to the site of injury, and leads to improved cognitive recovery following long-term treatment.

  2. Impairments in cognition and neural precursor cell proliferation in mice expressing constitutively active glycogen synthase kinase-3

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    Marta ePardo

    2015-03-01

    Full Text Available ABSTRACTBrain glycogen synthase kinase-3 (GSK3 is hyperactive in several neurological conditions that involve impairments in both cognition and neurogenesis. This raises the hypotheses that hyperactive GSK3 may directly contribute to impaired cognition, and that this may be related to deficiencies in neural precursor cells (NPC. To study the effects of hyperactive GSK3 in the absence of disease influences, we compared adult hippocampal NPC proliferation and performance in three cognitive tasks in male and female wild-type mice and GSK3 knockin mice, which express constitutively active GSK3. NPC proliferation was ~40% deficient in both male and female GSK3 knockin mice compared with wild-type mice. Environmental enrichment (EE increased NPC proliferation in male, but not female, GSK3 knockin mice and wild-type mice. Male and female GSK3 knockin mice exhibited impairments in novel object recognition, temporal order memory, and coordinate spatial processing compared with gender-matched wild-type mice. EE restored impaired novel object recognition and temporal ordering in both sexes of GSK3 knockin mice, indicating that this repair was not dependent on NPC proliferation, which was not increased by EE in female GSK3 knockin mice. Acute 1 hr pretreatment with the GSK3 inhibitor TDZD-8 also improved novel object recognition and temporal ordering in male and female GSK3 knockin mice. These findings demonstrate that hyperactive GSK3 is sufficient to impair adult hippocampal NPC proliferation and to impair performance in three cognitive tasks in both male and female mice, but these changes in NPC proliferation do not directly regulate novel object recognition and temporal ordering tasks.

  3. Negative regulation of TLX by IL-1β correlates with an inhibition of adult hippocampal neural precursor cell proliferation.

    Science.gov (United States)

    Ryan, Sinead M; O'Keeffe, Gerard W; O'Connor, Caitriona; Keeshan, Karen; Nolan, Yvonne M

    2013-10-01

    Adult hippocampal neurogenesis is modulated by a number of intrinsic and extrinsic factors including local signalling molecules, exercise, aging and inflammation. Inflammation is also a major contributor to several hippocampal-associated disorders. Interleukin-1beta (IL-1β) is the most predominant pro-inflammatory cytokine in the brain, and an increase in its concentration is known to decrease the proliferation of both embryonic and adult hippocampal neural precursor cells (NPCs). Recent research has focused on the role of nuclear receptors as intrinsic regulators of neurogenesis, and it is now established that the orphan nuclear receptor TLX is crucial in maintaining the NPC pool in neurogenic brain regions. To better understand the involvement of TLX in IL-1β-mediated effects on hippocampal NPC proliferation, we examined hippocampal NPC proliferation and TLX expression in response to IL-1β treatment in an adult rat hippocampal neurosphere culture system. We demonstrate that IL-1β reduced the proliferation of hippocampal NPCs and TLX expression in a dose and time-dependent manner and that co-treatment with IL-1β receptor antagonist or IL-1 receptor siRNA prevented these effects. We also report a dose-dependent effect of IL-1β on the composition of cell phenotypes in the culture and on expression of TLX in these cells. This study thus provides evidence of an involvement of TLX in IL-1β-induced changes in adult hippocampal neurogenesis, and offers mechanistic insight into disorders in which neuroinflammation and alterations in neurogenesis are characteristic features. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Pre-differentiated GABAergic neural precursor transplants for alleviation of dysesthetic central pain following excitotoxic spinal cord injury

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    Jeung Woon eLee

    2012-05-01

    Full Text Available Intraspinal quisqualic acid (QUIS injury induce (i mechanical and thermal hyperalgesia, (ii progressive self-injurious overgrooming of the affected dermatome. The latter is thought to resemble painful dysesthesia observed in spinal cord injury (SCI patients. We have reported previously loss of endogenous GABA immunoreactive (IR cells in the superficial dorsal horn of QUIS rats 2 weeks post-injury. Further histological evaluation showed that GABA-, glycine-, and synaptic vesicular transporter VIAAT-IR persisted but were substantially decreased in the injured spinal cord. In this study, partially-differentiated GABA-IR embryonic neural precursor cells (NPCs were transplanted into the spinal cord of QUIS rats to reverse overgrooming by replenishing lost inhibitory circuitry. Rat E14 NPCs were predifferentiated in 0.1 ng/ml FGF-2 for 4 hrs prior to transplantation. In vitro immunocytochemistry of transplant cohort showed large population of GABA-IR NPCs that double labeled with nestin but few co-localized with NeuN, indicating partial maturation. Two weeks following QUIS lesion at T12-L1, and following the onset of overgrooming, NPCs were transplanted into the QUIS lesion sites; bovine adrenal fibroblast cells were used as control. Overgrooming was reduced in >55.5% of NPC grafted animals, with inverse relationship between the number of surviving GABA-IR cells and the size of overgrooming. Fibroblast-control animals showed a progressive worsening of overgrooming. At 3 weeks post-transplantation, numerous GABA-, nestin-, and GFAP-IR cells were present in the lesion site. Surviving grafted GABA-IR NPCs were NeuN+ and GFAP-. These results indicate that partially-differentiated NPCs survive and differentiate in vivo into neuronal cells following transplantation into an injured spinal cord. GABA-IR NPC transplants can restore lost dorsal horn inhibitory signaling and are useful in alleviating central pain following SCI.

  5. Spin quenching assisted by a strongly anisotropic compression behavior in MnP

    Energy Technology Data Exchange (ETDEWEB)

    Han, Fei; Wang, Di; Wang, Yonggang; Li, Nana; Bao, Jin-Ke; Li, Bing; Botana, Antia S.; Xiao, Yuming; Chow, Paul; Chung, Duck Young; Chen, Jiuhua; Wan, Xiangang; Kanatzidis, Mercouri G.; Yang, Wenge; Mao, Ho-Kwang

    2018-02-01

    We studied the crystal structure and spin state of MnP under high pressure with synchrotron X-ray diffraction and X-ray emission spectroscopy. MnP has an exceedingly strong anisotropy in compressibility, with the primary compressible direction along the b axis of the Pnma structure. X-ray emission spectroscopy reveals a pressure-driven quenching of the spin state in MnP. First-principles calculations suggest that the strongly anisotropic compression behavior significantly enhances the dispersion of the Mn d-orbitals and the splitting of the d-orbital levels compared to the hypothetical isotropic compression behavior. Thus, we propose spin quenching results mainly from the significant enhancement of the itinerancy of d electrons and partly from spin rearrangement occurring in the split d-orbital levels near the Fermi level. This explains the fast suppression of magnetic ordering in MnP under high pressure. The spin quenching lags behind the occurrence of superconductivity at ~8 GPa implying that spin fluctuations govern the electron pairing for superconductivity.

  6. Opposing Effects of α2- and β-Adrenergic Receptor Stimulation on Quiescent Neural Precursor Cell Activity and Adult Hippocampal Neurogenesis

    Science.gov (United States)

    Prosper, Boris W.; Marathe, Swanand; Husain, Basma F. A.; Kernie, Steven G.; Bartlett, Perry F.; Vaidya, Vidita A.

    2014-01-01

    Norepinephrine regulates latent neural stem cell activity and adult hippocampal neurogenesis, and has an important role in modulating hippocampal functions such as learning, memory and mood. Adult hippocampal neurogenesis is a multi-stage process, spanning from the activation and proliferation of hippocampal stem cells, to their differentiation into neurons. However, the stage-specific effects of noradrenergic receptors in regulating adult hippocampal neurogenesis remain poorly understood. In this study, we used transgenic Nestin-GFP mice and neurosphere assays to show that modulation of α2- and β-adrenergic receptor activity directly affects Nestin-GFP/GFAP-positive precursor cell population albeit in an opposing fashion. While selective stimulation of α2-adrenergic receptors decreases precursor cell activation, proliferation and immature neuron number, stimulation of β-adrenergic receptors activates the quiescent precursor pool and enhances their proliferation in the adult hippocampus. Furthermore, our data indicate no major role for α1-adrenergic receptors, as we did not observe any change in either the activation and proliferation of hippocampal precursors following selective stimulation or blockade of α1-adrenergic receptors. Taken together, our data suggest that under physiological as well as under conditions that lead to enhanced norepinephrine release, the balance between α2- and β-adrenergic receptor activity regulates precursor cell activity and hippocampal neurogenesis. PMID:24922313

  7. Synthesis and structural characterization of Na 2 MnP 2 O 7 crystal

    Indian Academy of Sciences (India)

    Na2MnP2O7 crystals were synthesized by hydrothermal technique. Crystals obtained are in the form of single crystals of rhombohedral morphology with lattice parameters as follows: triclinic, 1 ¯ , = 0.71069 Å, = 6.657(3) Å, = 6.714(6) Å, = 6.518(4) Å, = 112.31(6)°, = 92.14(4)°, = 83.89(5)°, = 268.0(3) Å3, ...

  8. Activation of different neural precursor populations in the adult hippocampus: does this lead to new neurons with discrete functions?

    Science.gov (United States)

    Jhaveri, Dhanisha J; Taylor, Chanel J; Bartlett, Perry F

    2012-07-01

    Resident populations of stem and precursor cells drive the production of new neurons in the adult hippocampus. Recent discoveries have highlighted that a large proportion of these precursor cells are in fact quiescent and can be activated by distinct neuronal activity under both normal physiological and pathological conditions. As growing evidence indicates that newborn neurons play a critical role in cognitive functions such as learning and memory and in mood regulation, it is paramount that we obtain a better understanding of how the reservoirs of stem and precursor cells are maintained and activated. In this review, we critically examine the roles of key molecular mechanisms that have been shown to regulate hippocampal precursor cells, especially their activation. We believe that understanding the mechanistic details of the activity-driven regulation of precursor cells will equip us with the ability to develop tailored strategies to trigger the generation of new neurons, thereby improving the functional outcomes in various neurological and psychiatric conditions. Copyright © 2012 Wiley Periodicals, Inc.

  9. Diffraction imaging study of the phase coexistence around the triple point in MnP

    International Nuclear Information System (INIS)

    Medrano, C.; Pernot, E.; Espeso, J.I.; Boller, E.; Lorut, F.; Baruchel, J.

    2001-01-01

    The coexistence of the helimagnetic, ferromagnetic and fan phases in the neighborhood of the triple point is investigated by real-time Bragg diffraction imaging in a (0 0 1) MnP crystal. When increasing the field while retaining the heli-ferromagnetic coexistence, the nucleation of the fan phase occurs inside the present interface. The shapes and orientations of the heli-ferromagnetic and fan-helimagnetic interfaces can be understood by considering the corresponding elastic and/or magnetostatic energy. The ferromagnetic-fan thick interface, on the contrary, suggests the existence of intermediate states

  10. Bumetanide promotes neural precursor cell regeneration and dendritic development in the hippocampal dentate gyrus in the chronic stage of cerebral ischemia

    Directory of Open Access Journals (Sweden)

    Wang-shu Xu

    2016-01-01

    Full Text Available Bumetanide has been shown to lessen cerebral edema and reduce the infarct area in the acute stage of cerebral ischemia. Few studies focus on the effects of bumetanide on neuroprotection and neurogenesis in the chronic stage of cerebral ischemia. We established a rat model of cerebral ischemia by injecting endothelin-1 in the left cortical motor area and left corpus striatum. Seven days later, bumetanide 200 µg/kg/day was injected into the lateral ventricle for 21 consecutive days with a mini-osmotic pump. Results demonstrated that the number of neuroblasts cells and the total length of dendrites increased, escape latency reduced, and the number of platform crossings increased in the rat hippocampal dentate gyrus in the chronic stage of cerebral ischemia. These findings suggest that bumetanide promoted neural precursor cell regeneration, dendritic development and the recovery of cognitive function, and protected brain tissue in the chronic stage of ischemia.

  11. Septum magnet MNP-23 for the CERN PS experimental area and its fast interlock system

    CERN Document Server

    Borburgh, J; Prost, A; Zickler, T

    2004-01-01

    Two MNP-23 septum-like magnets are installed at CERN in the transfer line from the Proton Synchrotron (PS) to the East Hall Experimental Area. They are exposed to extremely high doses of ionizing radiation. In the past, the magnets experienced two catastrophic failures due to overheating of its coils and cannot be repaired. The magnets of improved design which is subject of this article are built as replacements for the magnets presently installed. The MNP-23 is a resistive C shaped iron-dominated magnet made of solid low carbon steel blocks. The excitation windings consist of two water-cooled coils wound from hollow copper conductor. The septum design of these magnets implies a high current density which requires an efficient water cooling system. The newly designed cooling circuit provides better cooling performance and more reliability. To avoid failures due to coil overheating, an elaborate interlock system was developed and installed. It consists of two parts: firstly a slow, more classic sensor, to dete...

  12. Decreased neural precursor cell pool in NADPH oxidase 2-deficiency: From mouse brain to neural differentiation of patient derived iPSC

    Directory of Open Access Journals (Sweden)

    Zeynab Nayernia

    2017-10-01

    Full Text Available There is emerging evidence for the involvement of reactive oxygen species (ROS in the regulation of stem cells and cellular differentiation. Absence of the ROS-generating NADPH oxidase NOX2 in chronic granulomatous disease (CGD patients, predominantly manifests as immune deficiency, but has also been associated with decreased cognition. Here, we investigate the role of NOX enzymes in neuronal homeostasis in adult mouse brain and in neural cells derived from human induced pluripotent stem cells (iPSC. High levels of NOX2 were found in mouse adult neurogenic regions. In NOX2-deficient mice, neurogenic regions showed diminished redox modifications, as well as decrease in neuroprecursor numbers and in expression of genes involved in neural differentiation including NES, BDNF and OTX2. iPSC from healthy subjects and patients with CGD were used to study the role of NOX2 in human in vitro neuronal development. Expression of NOX2 was low in undifferentiated iPSC, upregulated upon neural induction, and disappeared during neuronal differentiation. In human neurospheres, NOX2 protein and ROS generation were polarized within the inner cell layer of rosette structures. NOX2 deficiency in CGD-iPSCs resulted in an abnormal neural induction in vitro, as revealed by a reduced expression of neuroprogenitor markers (NES, BDNF, OTX2, NRSF/REST, and a decreased generation of mature neurons. Vector-mediated NOX2 expression in NOX2-deficient iPSCs rescued neurogenesis. Taken together, our study provides novel evidence for a regulatory role of NOX2 during early stages of neurogenesis in mouse and human.

  13. Radiation-induced apoptosis of neural precursors cell cultures: early modulation of the response mediated by reactive oxygen and nitrogen species (ROS/RNS)

    Energy Technology Data Exchange (ETDEWEB)

    Gisone, P.; Dubner, D.; Robello, E.; Michelin, S.; Perez, M. R.

    2004-07-01

    Apoptosis, the typical mode of radiation-induced cell death in developing Central Nervous System (CNS), is closely related with the oxidative status. Enhanced radiation-induced generation of ROS/RNS has been observed after exposures to low radiation doses leading to cellular amplification of signal transduction and further molecular and cellular radiation-responses. Moreover Nitric oxide (NO) and hydroxyl radical are implicated in dopaminergic neurotoxicity in different parading. This study is an attempt to address the participation of radiation-induced free radicals production, the contribution of endogenous NO generation, and the excitonic pathway, in the radiation-induced apoptosis of neural cortical precursors. Cortical cells obtained from at 17 gestational day (gd) were irradiated with doses from 0,2 Gy to 2 Gy at a dose-rate of 0.3 Gy/m. A significant decrease of Luminol-dependent Chemiluminescence was evident 30 m after irradiation reaching basal levels at 120 m follow for a tendency to increasing values Incubations with Superoxide Dismatuse (SOD) decreased significantly the chemiluminescence in irradiated samples NO content estimated by measuring the stable products NO{sub 2} and NO{sub 3} released to the culture medium in the same period, has shown a time-dependent accumulation from 1 h post-irradiation. the apoptosis, determined 24 h post-irradiation by flow cytometry, morphology and DNA fragmentation revealed a dose-effect relationship with significant differences from 0.4 Gy. The samples pre-treated with 10 mM of N-acetyl cysteine (NAC) a precursor of intracellular GSH synthesis, shown a significant decrease of the apoptosis. Apoptosis was significantly increased in irradiated cells after inhibition of nitric oxide synthase (NOS) byL-NAME. We conclude that ROS/RNS play a pivotal role in the early signaling pathways leading to a radiation-induced cell death. (Author) 40 refs.

  14. Radiation-induced apoptosis of neural precursors cell cultures: early modulation of the response mediated by reactive oxygen and nitrogen species (ROS/RNS)

    International Nuclear Information System (INIS)

    Gisone, P.; Dubner, D.; Robello, E.; Michelin, S.; Perez, M. R.

    2004-01-01

    Apoptosis, the typical mode of radiation-induced cell death in developing Central Nervous System (CNS), is closely related with the oxidative status. Enhanced radiation-induced generation of ROS/RNS has been observed after exposures to low radiation doses leading to cellular amplification of signal transduction and further molecular and cellular radiation-responses. Moreover Nitric oxide (NO) and hydroxyl radical are implicated in dopaminergic neurotoxicity in different parading. This study is an attempt to address the participation of radiation-induced free radicals production, the contribution of endogenous NO generation, and the excitonic pathway, in the radiation-induced apoptosis of neural cortical precursors. Cortical cells obtained from at 17 gestational day (gd) were irradiated with doses from 0,2 Gy to 2 Gy at a dose-rate of 0.3 Gy/m. A significant decrease of Luminol-dependent Chemiluminescence was evident 30 m after irradiation reaching basal levels at 120 m follow for a tendency to increasing values Incubations with Superoxide Dismatuse (SOD) decreased significantly the chemiluminescence in irradiated samples NO content estimated by measuring the stable products NO 2 and NO 3 released to the culture medium in the same period, has shown a time-dependent accumulation from 1 h post-irradiation. the apoptosis, determined 24 h post-irradiation by flow cytometry, morphology and DNA fragmentation revealed a dose-effect relationship with significant differences from 0.4 Gy. The samples pre-treated with 10 mM of N-acetyl cysteine (NAC) a precursor of intracellular GSH synthesis, shown a significant decrease of the apoptosis. Apoptosis was significantly increased in irradiated cells after inhibition of nitric oxide synthase (NOS) byL-NAME. We conclude that ROS/RNS play a pivotal role in the early signaling pathways leading to a radiation-induced cell death. (Author) 40 refs

  15. A zebrafish model of lethal congenital contracture syndrome 1 reveals Gle1 function in spinal neural precursor survival and motor axon arborization.

    Science.gov (United States)

    Jao, Li-En; Appel, Bruce; Wente, Susan R

    2012-04-01

    In humans, GLE1 is mutated in lethal congenital contracture syndrome 1 (LCCS1) leading to prenatal death of all affected fetuses. Although the molecular roles of Gle1 in nuclear mRNA export and translation have been documented, no animal models for this disease have been reported. To elucidate the function of Gle1 in vertebrate development, we used the zebrafish (Danio rerio) model system. gle1 mRNA is maternally deposited and widely expressed. Altering Gle1 using an insertional mutant or antisense morpholinos results in multiple defects, including immobility, small eyes, diminished pharyngeal arches, curved body axis, edema, underdeveloped intestine and cell death in the central nervous system. These phenotypes parallel those observed in LCCS1 human fetuses. Gle1 depletion also results in reduction of motoneurons and aberrant arborization of motor axons. Unexpectedly, the motoneuron deficiency results from apoptosis of neural precursors, not of differentiated motoneurons. Mosaic analyses further indicate that Gle1 activity is required extrinsically in the environment for normal motor axon arborization. Importantly, the zebrafish phenotypes caused by Gle1 deficiency are only rescued by expressing wild-type human GLE1 and not by the disease-linked Fin(Major) mutant form of GLE1. Together, our studies provide the first functional characterization of Gle1 in vertebrate development and reveal its essential role in actively dividing cells. We propose that defective GLE1 function in human LCCS1 results in both neurogenic and non-neurogenic defects linked to the apoptosis of proliferative organ precursors.

  16. BDNF Increases Survival and Neuronal Differentiation of Human Neural Precursor Cells Cotransplanted with a Nanofiber Gel to the Auditory Nerve in a Rat Model of Neuronal Damage

    Directory of Open Access Journals (Sweden)

    Yu Jiao

    2014-01-01

    Full Text Available Objectives. To study possible nerve regeneration of a damaged auditory nerve by the use of stem cell transplantation. Methods. We transplanted HNPCs to the rat AN trunk by the internal auditory meatus (IAM. Furthermore, we studied if addition of BDNF affects survival and phenotypic differentiation of the grafted HNPCs. A bioactive nanofiber gel (PA gel, in selected groups mixed with BDNF, was applied close to the implanted cells. Before transplantation, all rats had been deafened by a round window niche application of β-bungarotoxin. This neurotoxin causes a selective toxic destruction of the AN while keeping the hair cells intact. Results. Overall, HNPCs survived well for up to six weeks in all groups. However, transplants receiving the BDNF-containing PA gel demonstrated significantly higher numbers of HNPCs and neuronal differentiation. At six weeks, a majority of the HNPCs had migrated into the brain stem and differentiated. Differentiated human cells as well as neurites were observed in the vicinity of the cochlear nucleus. Conclusion. Our results indicate that human neural precursor cells (HNPC integration with host tissue benefits from additional brain derived neurotrophic factor (BDNF treatment and that these cells appear to be good candidates for further regenerative studies on the auditory nerve (AN.

  17. Thyroid hormone participates in the regulation of neural stem cells and oligodendrocyte precursor cells in the central nervous system of adult rat.

    Science.gov (United States)

    Fernandez, M; Pirondi, S; Manservigi, M; Giardino, L; Calzà, L

    2004-10-01

    Oligodendrocyte development and myelination are under thyroid hormone control. In this study we analysed the effects of chronic manipulation of thyroid status on the expression of a wide spectrum of oligodendrocyte precursor cells (OPCs) markers and myelin basic protein (MBP) in the subventricular zone (SVZ), olfactory bulb and optic nerve, and on neural stem cell (NSC) lineage in adult rats. Hypo- and hyperthyroidism were induced in male rats, by propyl-thio-uracil (PTU) and L-thyroxin (T4) treatment, respectively. Hypothyroidism increased and hyperthyroidism downregulated proliferation in the SVZ and olfactory bulb (Ki67 immunohistochemistry and Western blotting, bromodeoxyuridine uptake). Platelet-derived growth factor receptor alpha (PDGFalpha-R) and MBP mRNA levels decreased in the optic nerve of hypothyroid rats; the same also occurred at the level of MBP protein. Hyperthyroidism slightly upregulates selected markers such as NG2 in the olfactory bulb. The lineage of cells derived from primary cultures of NSC prepared from the forebrain of adult hypo- and hyperthyroid also differs from those derived from control animals. Although no difference of in vitro proliferation of NSCs was observed in the presence of epidermal growth factor, maturation of oligodendrocytes (defined by process number and length) was enhanced in hyperthyroidism, suggesting a more mature state than in control animals. This difference was even greater when compared with the hypothyroid group, the morphology of which suggested a delay in differentiation. These results indicate that thyroid hormone affects NSC and OPC proliferation and maturation also in adulthood.

  18. Neural tissue-spheres

    DEFF Research Database (Denmark)

    Andersen, Rikke K; Johansen, Mathias; Blaabjerg, Morten

    2007-01-01

    By combining new and established protocols we have developed a procedure for isolation and propagation of neural precursor cells from the forebrain subventricular zone (SVZ) of newborn rats. Small tissue blocks of the SVZ were dissected and propagated en bloc as free-floating neural tissue...... content, thus allowing experimental studies of neural precursor cells and their niche...

  19. Changes in expression of the long noncoding RNA FMR4 associate with altered gene expression during differentiation of human neural precursor cells

    Directory of Open Access Journals (Sweden)

    Veronica Julia Peschansky

    2015-08-01

    Full Text Available CGG repeat expansions in the Fragile X mental retardation 1 (FMR1 gene are responsible for a family of associated disorders characterized by either intellectual disability and autism (Fragile X Syndrome, FXS, or adult-onset neurodegeneration (Fragile X-associated Tremor/Ataxia Syndrome, FXTAS. However, the FMR1 locus is complex and encodes several long noncoding RNAs (lncRNAs, whose expression is altered by repeat expansion mutations.The role of these lncRNAs is thus far unknown; therefore we investigated the functionality of FMR4, which we previously identified. Full-length expansions of the FMR1 triplet repeat cause silencing of both FMR1 and FMR4, thus we are interested in potential loss-of-function that may add to phenotypic manifestation of FXS. Since the two transcripts do not exhibit cis-regulation of one another, we examined the potential for FMR4 to regulate target genes at distal genomic loci using gene expression microarrays. We identified FMR4-responsive genes, including the methyl-CpG-binding domain protein 4 (MBD4. Furthermore, we found that in differentiating human neural precursor cells (hNPCs, FMR4 expression is developmentally regulated in opposition to expression of both FMR1 (which is expected to share a bidirectional promoter with FMR4 and MBD4.We therefore propose that FMR4’s function is as a gene-regulatory lncRNA and that this transcript may function in normal development. Closer examination of FMR4 increases our understanding of the role of regulatory lncRNA and the consequences of FMR1 repeat expansions.

  20. Remyelination Is Correlated with Regulatory T Cell Induction Following Human Embryoid Body-Derived Neural Precursor Cell Transplantation in a Viral Model of Multiple Sclerosis.

    Directory of Open Access Journals (Sweden)

    Warren C Plaisted

    Full Text Available We have recently described sustained clinical recovery associated with dampened neuroinflammation and remyelination following transplantation of neural precursor cells (NPCs derived from human embryonic stem cells (hESCs in a viral model of the human demyelinating disease multiple sclerosis. The hNPCs used in that study were derived by a novel direct differentiation method (direct differentiation, DD-NPCs that resulted in a unique gene expression pattern when compared to hNPCs derived by conventional methods. Since the therapeutic potential of human NPCs may differ greatly depending on the method of derivation and culture, we wanted to determine whether NPCs differentiated using conventional methods would be similarly effective in improving clinical outcome under neuroinflammatory demyelinating conditions. For the current study, we utilized hNPCs differentiated from a human induced pluripotent cell line via an embryoid body intermediate stage (EB-NPCs. Intraspinal transplantation of EB-NPCs into mice infected with the neurotropic JHM strain of mouse hepatitis virus (JHMV resulted in decreased accumulation of CD4+ T cells in the central nervous system that was concomitant with reduced demyelination at the site of injection. Dampened neuroinflammation and remyelination was correlated with a transient increase in CD4+FOXP3+ regulatory T cells (Tregs concentrated within the peripheral lymphatics. However, compared to our earlier study, pathological improvements were modest and did not result in significant clinical recovery. We conclude that the genetic signature of NPCs is critical to their effectiveness in this model of viral-induced neurologic disease. These comparisons will be useful for understanding what factors are critical for the sustained clinical improvement.

  1. An In Vivo Characterization of Trophic Factor Production Following Neural Precursor Cell or Bone Marrow Stromal Cell Transplantation for Spinal Cord Injury

    Science.gov (United States)

    Hawryluk, Gregory W.J.; Mothe, Andrea; Wang, Jian; Wang, Shelly; Tator, Charles

    2012-01-01

    Cellular transplantation strategies for repairing the injured spinal cord have shown consistent benefit in preclinical models, and human clinical trials have begun. Interactions between transplanted cells and host tissue remain poorly understood. Trophic factor secretion is postulated a primary or supplementary mechanism of action for many transplanted cells, however, there is little direct evidence to support trophin production by transplanted cells in situ. In the present study, trophic factor expression was characterized in uninjured, injured-untreated, injured-treated with transplanted cells, and corresponding control tissue from the adult rat spinal cord. Candidate trophic factors were identified in a literature search, and primers were designed for these genes. We examined in vivo trophin expression in 3 paradigms involving transplantation of either brain or spinal cord-derived neural precursor cells (NPCs) or bone marrow stromal cells (BMSCs). Injury without further treatment led to a significant elevation of nerve growth factor (NGF), leukemia inhibitory factor (LIF), insulin-like growth factor-1 (IGF-1), and transforming growth factor-β1 (TGF-β1), and lower expression of vascular endothelial growth factor isoform A (VEGF-A) and platelet-derived growth factor-A (PDGF-A). Transplantation of NPCs led to modest changes in trophin expression, and the co-administration of intrathecal trophins resulted in significant elevation of the neurotrophins, glial-derived neurotrophic factor (GDNF), LIF, and basic fibroblast growth factor (bFGF). BMSCs transplantation upregulated NGF, LIF, and IGF-1. NPCs isolated after transplantation into the injured spinal cord expressed the neurotrophins, ciliary neurotrophic factor (CNTF), epidermal growth factor (EGF), and bFGF at higher levels than host cord. These data show that trophin expression in the spinal cord is influenced by injury and cell transplantation, particularly when combined with intrathecal trophin infusion

  2. OTX2 exhibits cell-context-dependent effects on cellular and molecular properties of human embryonic neural precursors and medulloblastoma cells

    Directory of Open Access Journals (Sweden)

    Ravinder Kaur

    2015-10-01

    Full Text Available Medulloblastoma (MB is the most common malignant primary pediatric brain tumor and is currently divided into four subtypes based on different genomic alterations, gene expression profiles and response to treatment: WNT, Sonic Hedgehog (SHH, Group 3 and Group 4. This extensive heterogeneity has made it difficult to assess the functional relevance of genes to malignant progression. For example, expression of the transcription factor Orthodenticle homeobox2 (OTX2 is frequently dysregulated in multiple MB variants; however, its role may be subtype specific. We recently demonstrated that neural precursors derived from transformed human embryonic stem cells (trans-hENs, but not their normal counterparts (hENs, resemble Groups 3 and 4 MB in vitro and in vivo. Here, we tested the utility of this model system as a means of dissecting the role of OTX2 in MB using gain- and loss-of-function studies in hENs and trans-hENs, respectively. Parallel experiments with MB cells revealed that OTX2 exerts inhibitory effects on hEN and SHH MB cells by regulating growth, self-renewal and migration in vitro and tumor growth in vivo. This was accompanied by decreased expression of pluripotent genes, such as SOX2, and was supported by overexpression of SOX2 in OTX2+ SHH MB and hENs that resulted in significant rescue of self-renewal and cell migration. By contrast, OTX2 is oncogenic and promotes self-renewal of trans-hENs and Groups 3 and 4 MB independent of pluripotent gene expression. Our results demonstrate a novel role for OTX2 in self-renewal and migration of hENs and MB cells and reveal a cell-context-dependent link between OTX2 and pluripotent genes. Our study underscores the value of human embryonic stem cell derivatives as alternatives to cell lines and heterogeneous patient samples for investigating the contribution of key developmental regulators to MB progression.

  3. Optoelectronic figure of merit of a metal nanoparticle—quantum dot (MNP-QD) hybrid molecule for assessing its suitability for sensing applications

    Science.gov (United States)

    Hapuarachchi, Harini; Mallawaarachchi, Sudaraka; Hattori, Haroldo T.; Zhu, Weiren; Premaratne, Malin

    2018-02-01

    Recently, many have studied various configurations of metal nanoparticle-quantum dot (MNP-QD) hybrid molecules based on different metals and tunable parameters. In this paper, we aim to incite the interest in using MNP-QD nanohybrids, which possess sensing capabilities superior to those of the individual constituents, for sensing applications that rely on scattered light. When assessing whether a given MNP-QD configuration is suited for an application, sometimes it is hard to assess the pros and cons of a given configuration against other candidates. Here we propose a simple, elegant relative figure of merit (RFoM), which focuses on maximizing the scattered intensity and the refractive index sensitivity of the nanohybrid, to rank the suitability of viable MNP-QD configurations for a particular sensing application. We use the proposed RFoM to analyse the optical spectra of noble, transition, post transition and alkali metal based MNP-QD nanohybrids using the representative metals Au, Ag, Cu, Al and Na, adopting a generalized nonlocal optical response (GNOR) method based cavity QED approach. Based on our observations, we suggest how the usage of MNP-QD nanohybrids could improve the conventionally studied tumour targeting applications. Moreover, we propose potential substitutes for noble metals conventionally considered for MNP-QD nanohybrids.

  4. The Use of Human-Induced Pluripotent Stem Cell-Derived Neural Precursors in the Treatment of Brain and Spinal Cord Injury

    Czech Academy of Sciences Publication Activity Database

    Jendelová, Pavla; Kozubenko, Nataliya; Amemori, Takashi; Turnovcová, Karolína; Seminatore, CH.; Jirák, D.; Onteniente, B.; Syková, Eva

    2011-01-01

    Roč. 20, č. 4 (2011), s. 564-564 ISSN 0963-6897. [International Neural Transplantatioin and Repair Meeting/18th Annual Meeting of the American-Society-for- Neural - Therapy - and -Repair /11./. 04.05.2011-08.05.2011, Clearwater] Institutional research plan: CEZ:AV0Z50390703 Keywords : spinal cord * stem cell Subject RIV: FH - Neurology

  5. Using daily text messages to improve adherence to infant micronutrient powder (MNP) packets in rural western China: A cluster-randomized controlled trial.

    Science.gov (United States)

    Wang, Xu; Luo, Renfu; Liu, Chengfang; Zhang, Linxiu; Yue, Ai; Medina, Alexis; Rozelle, Scott

    2018-01-01

    To evaluate the effectiveness of daily text messages as a means to improve caregivers' adherence to infant micronutrient powder (MNP) in rural Shaanxi Province of China. 638 infants aged 6-11 months in 234 villages were involved in a cluster-randomized controlled trial (RCT). All caregivers were given free infant MNP packets at baseline in April 2013 and the follow-up survey was in July 2013. We randomly assigned 318 infants in 117 villages to treatment group (receiving daily text message) and 320 infants in the other 117 villages as control group. On average, daily text messages increased the number of MNP packets fed (marginal effect = 4.63; 95% confidence interval (CI) = 0.16, 9.10). The text message is more likely to increase the consumption of MNP packets if the primary caregiver was the mother (marginal effect = 12.19; 95% CI = 0.69, 23.68). Receiving the text message appears to significantly increase the likelihood of full adherence when the primary caregiver can either check (odds ratio = 2.93; 95% CI = 1.34, 6.40) or knows how to send (odds ratio = 3.26; 95% CI = 1.53, 6.97) text messages. Daily text messages improved the consumption of infant MNP packets. However, the impact was not large enough to increase the probability of caregivers being fully adherent to the feeding instruction, which is to feed 5-7 packets per week as recommended. In addition, when the mother is the caregiver and when the caregiver can check or knows how to send text messages there is greater adherence by the primary caregivers. http://www.isrctn.com/ISRCTN44149146.

  6. Using daily text messages to improve adherence to infant micronutrient powder (MNP) packets in rural western China: A cluster-randomized controlled trial

    Science.gov (United States)

    Wang, Xu; Liu, Chengfang; Zhang, Linxiu; Yue, Ai; Medina, Alexis; Rozelle, Scott

    2018-01-01

    Objective To evaluate the effectiveness of daily text messages as a means to improve caregivers’ adherence to infant micronutrient powder (MNP) in rural Shaanxi Province of China. Methodology 638 infants aged 6–11 months in 234 villages were involved in a cluster-randomized controlled trial (RCT). All caregivers were given free infant MNP packets at baseline in April 2013 and the follow-up survey was in July 2013. We randomly assigned 318 infants in 117 villages to treatment group (receiving daily text message) and 320 infants in the other 117 villages as control group. Results On average, daily text messages increased the number of MNP packets fed (marginal effect = 4.63; 95% confidence interval (CI) = 0.16, 9.10). The text message is more likely to increase the consumption of MNP packets if the primary caregiver was the mother (marginal effect = 12.19; 95% CI = 0.69, 23.68). Receiving the text message appears to significantly increase the likelihood of full adherence when the primary caregiver can either check (odds ratio = 2.93; 95% CI = 1.34, 6.40) or knows how to send (odds ratio = 3.26; 95% CI = 1.53, 6.97) text messages. Conclusion Daily text messages improved the consumption of infant MNP packets. However, the impact was not large enough to increase the probability of caregivers being fully adherent to the feeding instruction, which is to feed 5–7 packets per week as recommended. In addition, when the mother is the caregiver and when the caregiver can check or knows how to send text messages there is greater adherence by the primary caregivers. Trial registration http://www.isrctn.com/ISRCTN44149146 PMID:29352304

  7. Thermoset precursor

    International Nuclear Information System (INIS)

    Yamamoto, Y.

    1983-04-01

    This invention pertains to a distinctive thermoset precursor which is prepared by mixing a resin composition (A) which can be hardened by ionizing radiation, and a resin composition (B) which can be hardened by heat but cannot be hardened by, or is resistant to, ionizing radiation, and by coating or impregnating a molding or other substrate with a sheet or film of this mixture and irradiating this with an ionizing radiation. The principal components of composition (A) and (B) can be the following: (1) an acrylate or methacrylate and an epoxy resin and an epoxy resin hardener; (2) an unsaturated polyester resin and epoxy resin and an epoxy resin hardener; (3) a diacrylate or dimethacrylate or polyethylene glycol and an epoxy resin; (4) an epoxy acrylates or epoxy methacrylate obtained by the addition reaction of epoxy resin and acrylic or methacrylic acid

  8. Investigation on Possibility of Transferring OysterMushroom (Pleurotusostreatus Manganese Peroxidase Gene (mnp to the White Button Mushroom (Agaricusbisporus

    Directory of Open Access Journals (Sweden)

    Mojgan Parvandi

    2017-12-01

    , low flexibility and adaptability with environmental conditions changes are some of the problems that the mushroom reformers are faced. Unlike the great efforts made by researchers, conventional breeding techniques to produce the A. bisporus mushroom only have been led to produce a few new races. Therefore, todays some problems associated with traditional methods of breeding of edible mushrooms, including the need to provide races that have desired characteristics, the traditional method performance tests and low chances of success in the transfer of important agronomic characteristics such as functionality and disease resistance. So, they almost have been replaced with new biotechnology methods. Anexample of this method is to manipulateproperties transformation for the particular purpose. Modification of both expression or type of lignin degrading enzyme are possible solutions to deal with this problem, but these are not applicable or are difficult to be done with traditional breeding programs. In recent years, gene transformation mediated with Agrobacterium routinely is used for gene transformation to mushrooms and is proposed as a method for removing limitations of white button mushroom breeding. Materials and Methods: In this research, the oyster mushroom strain Florida was used as the source of manganese peroxidase (mnp gene and white button mushroom strain 737 gill and cap tissue were used as transformation host. Agrobacterium strain LBA4404 harbors p133H88-FM plasmid thatcontainsmnp gene of oyster mushroom and also hph gene under control of gpdII promoter of the button white mushroom strain IM008 was used as a transformer. Selection medium containing 30 mg/ml Hygromycin B and was used for selecting transformed explants. To confirm transformation, PCR with specific primers of mnp and hph genes was performed on genomic DNA of selected colonies. Results and Discussion: Results showed the gill tissue explants, with transformation rate 5%, have a better response to

  9. Apical Polarity Protein PrkCi Is Necessary for Maintenance of Spinal Cord Precursors in Zebrafish

    OpenAIRE

    Roberts, Randolph K.; Appel, Bruce

    2009-01-01

    During development, neural precursors divide to produce new precursors and cells that differentiate as neurons and glia. In Drosophila, apicobasal polarity and orientation of the mitotic spindle play important roles in specifying the progeny of neural precursors for different fates. We examined orientation of zebrafish spinal cord precursors using time-lapse imaging and tested the function of protein kinase C, iota (PrkCi), a member of the Par complex of proteins necessary for apicobasal pola...

  10. Brand Choice Modeling Modeling Toothpaste Brand Choice: An Empirical Comparison of Artificial Neural Networks and Multinomial Probit Model

    Directory of Open Access Journals (Sweden)

    Tolga Kaya

    2010-11-01

    Full Text Available The purpose of this study is to compare the performances of Artificial Neural Networks (ANN and Multinomial Probit (MNP approaches in modeling the choice decision within fast moving consumer goods sector. To do this, based on 2597 toothpaste purchases of a panel sample of 404 households, choice models are built and their performances are compared on the 861 purchases of a test sample of 135 households. Results show that ANN's predictions are better while MNP is useful in providing marketing insight.

  11. Ionospheric earthquake precursors

    International Nuclear Information System (INIS)

    Bulachenko, A.L.; Oraevskij, V.N.; Pokhotelov, O.A.; Sorokin, V.N.; Strakhov, V.N.; Chmyrev, V.M.

    1996-01-01

    Results of experimental study on ionospheric earthquake precursors, program development on processes in the earthquake focus and physical mechanisms of formation of various type precursors are considered. Composition of experimental cosmic system for earthquake precursors monitoring is determined. 36 refs., 5 figs

  12. Earthquakes: hydrogeochemical precursors

    Science.gov (United States)

    Ingebritsen, Steven E.; Manga, Michael

    2014-01-01

    Earthquake prediction is a long-sought goal. Changes in groundwater chemistry before earthquakes in Iceland highlight a potential hydrogeochemical precursor, but such signals must be evaluated in the context of long-term, multiparametric data sets.

  13. Survival and differentiation of human embryonic stem cell-derived neural precursors grafted spinally in spinal ischemia-injured rats or in naive immunosuppressed minipigs: a qualitative and quantitative study

    Czech Academy of Sciences Publication Activity Database

    Kakinohana, O.; Juhásová, Jana; Juhás, Štefan; Motlík, Jan; Platoshyn, O.; Galik, J.; Hefferan, M. P.; Yuan, S. H.; Vidal, J. G.; Carson, C. T.; Van Gorp, S.; Goldberg, D.; Leerink, M.; Lazar, P.; Maršala, S.; Miyanohara, A.; Keshavarzi, S.; Ciacci, J. D.; Maršala, M.

    2012-01-01

    Roč. 21, č. 12 (2012), s. 2603-2619 ISSN 0963-6897 R&D Projects: GA MŠk 1M0538; GA TA ČR TA01011466 Institutional research plan: CEZ:AV0Z50450515 Keywords : spinal cord ischemia * human embryonic stem (ES) cells * neuronal precursors (NPCs) Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.422, year: 2012

  14. The EM Earthquake Precursor

    Science.gov (United States)

    Jones, K. B., II; Saxton, P. T.

    2013-12-01

    Many attempts have been made to determine a sound forecasting method regarding earthquakes and warn the public in turn. Presently, the animal kingdom leads the precursor list alluding to a transmission related source. By applying the animal-based model to an electromagnetic (EM) wave model, various hypotheses were formed, but the most interesting one required the use of a magnetometer with a differing design and geometry. To date, numerous, high-end magnetometers have been in use in close proximity to fault zones for potential earthquake forecasting; however, something is still amiss. The problem still resides with what exactly is forecastable and the investigating direction of EM. After the 1989 Loma Prieta Earthquake, American earthquake investigators predetermined magnetometer use and a minimum earthquake magnitude necessary for EM detection. This action was set in motion, due to the extensive damage incurred and public outrage concerning earthquake forecasting; however, the magnetometers employed, grounded or buried, are completely subject to static and electric fields and have yet to correlate to an identifiable precursor. Secondly, there is neither a networked array for finding any epicentral locations, nor have there been any attempts to find even one. This methodology needs dismissal, because it is overly complicated, subject to continuous change, and provides no response time. As for the minimum magnitude threshold, which was set at M5, this is simply higher than what modern technological advances have gained. Detection can now be achieved at approximately M1, which greatly improves forecasting chances. A propagating precursor has now been detected in both the field and laboratory. Field antenna testing conducted outside the NE Texas town of Timpson in February, 2013, detected three strong EM sources along with numerous weaker signals. The antenna had mobility, and observations were noted for recurrence, duration, and frequency response. Next, two

  15. Identified EM Earthquake Precursors

    Science.gov (United States)

    Jones, Kenneth, II; Saxton, Patrick

    2014-05-01

    Many attempts have been made to determine a sound forecasting method regarding earthquakes and warn the public in turn. Presently, the animal kingdom leads the precursor list alluding to a transmission related source. By applying the animal-based model to an electromagnetic (EM) wave model, various hypotheses were formed, but the most interesting one required the use of a magnetometer with a differing design and geometry. To date, numerous, high-end magnetometers have been in use in close proximity to fault zones for potential earthquake forecasting; however, something is still amiss. The problem still resides with what exactly is forecastable and the investigating direction of EM. After a number of custom rock experiments, two hypotheses were formed which could answer the EM wave model. The first hypothesis concerned a sufficient and continuous electron movement either by surface or penetrative flow, and the second regarded a novel approach to radio transmission. Electron flow along fracture surfaces was determined to be inadequate in creating strong EM fields, because rock has a very high electrical resistance making it a high quality insulator. Penetrative flow could not be corroborated as well, because it was discovered that rock was absorbing and confining electrons to a very thin skin depth. Radio wave transmission and detection worked with every single test administered. This hypothesis was reviewed for propagating, long-wave generation with sufficient amplitude, and the capability of penetrating solid rock. Additionally, fracture spaces, either air or ion-filled, can facilitate this concept from great depths and allow for surficial detection. A few propagating precursor signals have been detected in the field occurring with associated phases using custom-built loop antennae. Field testing was conducted in Southern California from 2006-2011, and outside the NE Texas town of Timpson in February, 2013. The antennae have mobility and observations were noted for

  16. The safety, immunogenicity, and acceptability of inactivated influenza vaccine delivered by microneedle patch (TIV-MNP 2015): a randomised, partly blinded, placebo-controlled, phase 1 trial.

    Science.gov (United States)

    Rouphael, Nadine G; Paine, Michele; Mosley, Regina; Henry, Sebastien; McAllister, Devin V; Kalluri, Haripriya; Pewin, Winston; Frew, Paula M; Yu, Tianwei; Thornburg, Natalie J; Kabbani, Sarah; Lai, Lilin; Vassilieva, Elena V; Skountzou, Ioanna; Compans, Richard W; Mulligan, Mark J; Prausnitz, Mark R

    2017-08-12

    Microneedle patches provide an alternative to conventional needle-and-syringe immunisation, and potentially offer improved immunogenicity, simplicity, cost-effectiveness, acceptability, and safety. We describe safety, immunogenicity, and acceptability of the first-in-man study on single, dissolvable microneedle patch vaccination against influenza. The TIV-MNP 2015 study was a randomised, partly blinded, placebo-controlled, phase 1, clinical trial at Emory University that enrolled non-pregnant, immunocompetent adults from Atlanta, GA, USA, who were aged 18-49 years, naive to the 2014-15 influenza vaccine, and did not have any significant dermatological disorders. Participants were randomly assigned (1:1:1:1) to four groups and received a single dose of inactivated influenza vaccine (fluvirin: 18 μg of haemagglutinin per H1N1 vaccine strain, 17 μg of haemagglutinin per H3N2 vaccine strain, and 15 μg of haemagglutinin per B vaccine strain) (1) by microneedle patch or (2) by intramuscular injection, or received (3) placebo by microneedle patch, all administered by an unmasked health-care worker; or received a single dose of (4) inactivated influenza vaccine by microneedle patch self-administered by study participants. A research pharmacist prepared the randomisation code using a computer-generated randomisation schedule with a block size of 4. Because of the nature of the study, participants were not masked to the type of vaccination method (ie, microneedle patch vs intramuscular injection). Primary safety outcome measures are the incidence of study product-related serious adverse events within 180 days, grade 3 solicited or unsolicited adverse events within 28 days, and solicited injection site and systemic reactogenicity on the day of study product administration through 7 days after administration, and secondary safety outcomes are new-onset chronic illnesses within 180 days and unsolicited adverse events within 28 days, all analysed by intention to treat

  17. Chondroitin sulfate effects on neural stem cell differentiation.

    Science.gov (United States)

    Canning, David R; Brelsford, Natalie R; Lovett, Neil W

    2016-01-01

    We have investigated the role chondroitin sulfate has on cell interactions during neural plate formation in the early chick embryo. Using tissue culture isolates from the prospective neural plate, we have measured neural gene expression profiles associated with neural stem cell differentiation. Removal of chondroitin sulfate from stage 4 neural plate tissue leads to altered associations of N-cadherin-positive neural progenitors and causes changes in the normal sequence of neural marker gene expression. Absence of chondroitin sulfate in the neural plate leads to reduced Sox2 expression and is accompanied by an increase in the expression of anterior markers of neural regionalization. Results obtained in this study suggest that the presence of chondroitin sulfate in the anterior chick embryo is instrumental in maintaining cells in the neural precursor state.

  18. Direct Genesis of Functional Rodent and Human Schwann Cells from Skin Mesenchymal Precursors

    Directory of Open Access Journals (Sweden)

    Matthew P. Krause

    2014-07-01

    Full Text Available Recent reports of directed reprogramming have raised questions about the stability of cell lineages. Here, we have addressed this issue, focusing upon skin-derived precursors (SKPs, a dermally derived precursor cell. We show by lineage tracing that murine SKPs from dorsal skin originate from mesenchymal and not neural crest-derived cells. These mesenchymally derived SKPs can, without genetic manipulation, generate functional Schwann cells, a neural crest cell type, and are highly similar at the transcriptional level to Schwann cells isolated from the peripheral nerve. This is not a mouse-specific phenomenon, since human SKPs that are highly similar at the transcriptome level can be made from neural crest-derived facial and mesodermally derived foreskin dermis and the foreskin SKPs can make myelinating Schwann cells. Thus, nonneural crest-derived mesenchymal precursors can differentiate into bona fide peripheral glia in the absence of genetic manipulation, suggesting that developmentally defined lineage boundaries are more flexible than widely thought.

  19. Cryopreservation of GABAergic Neuronal Precursors for Cell-Based Therapy.

    Directory of Open Access Journals (Sweden)

    Daniel Rodríguez-Martínez

    Full Text Available Cryopreservation protocols are essential for stem cells storage in order to apply them in the clinic. Here we describe a new standardized cryopreservation protocol for GABAergic neural precursors derived from the medial glanglionic eminence (MGE, a promising source of GABAergic neuronal progenitors for cell therapy against interneuron-related pathologies. We used 10% Me2SO as cryoprotectant and assessed the effects of cell culture amplification and cellular organization, as in toto explants, neurospheres, or individualized cells, on post-thaw cell viability and retrieval. We confirmed that in toto cryopreservation of MGE explants is an optimal preservation system to keep intact the interneuron precursor properties for cell transplantation, together with a high cell viability (>80% and yield (>70%. Post-thaw proliferation and self-renewal of the cryopreserved precursors were tested in vitro. In addition, their migration capacity, acquisition of mature neuronal morphology, and potency to differentiate into multiple interneuron subtypes were also confirmed in vivo after transplantation. The results show that the cryopreserved precursor features remained intact and were similar to those immediately transplanted after their dissection from the MGE. We hope this protocol will facilitate the generation of biobanks to obtain a permanent and reliable source of GABAergic precursors for clinical application in cell-based therapies against interneuronopathies.

  20. Preparation of superconductor precursor powders

    Science.gov (United States)

    Bhattacharya, Raghunath

    1998-01-01

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

  1. Toward a theory of precursors

    International Nuclear Information System (INIS)

    Freivogel, Ben; Giddings, Steven B.; Lippert, Matthew

    2002-01-01

    To better understand the possible breakdown of locality in quantum gravitational systems, we pursue the identity of precursors in the context of the anti-de Sitter/conformal field theory correspondence. Holography implies a breakdown of standard bulk locality which we expect to occur only at extremely high energy. We consider precursors that encode bulk information causally disconnected from the boundary and whose measurement involves nonlocal bulk processes. We construct a toy model of holography which encapsulates the expected properties of precursors and compare it with previous such discussions. If these precursors can be identified in the gauge theory, they are almost certainly Wilson loops, perhaps with decorations, but the relevant information is encoded in the high-energy sector of the theory and should not be observable by low energy measurements. This would be in accord with the locality bound, which serves as a criterion for situations where breakdown of bulk locality is expected

  2. Synaptic network activity induces neuronal differentiation of adult hippocampal precursor cells through BDNF signaling

    Directory of Open Access Journals (Sweden)

    Harish Babu

    2009-09-01

    Full Text Available Adult hippocampal neurogenesis is regulated by activity. But how do neural precursor cells in the hippocampus respond to surrounding network activity and translate increased neural activity into a developmental program? Here we show that long-term potential (LTP-like synaptic activity within a cellular network of mature hippocampal neurons promotes neuronal differentiation of newly generated cells. In co-cultures of precursor cells with primary hippocampal neurons, LTP-like synaptic plasticity induced by addition of glycine in Mg2+-free media for 5 min, produced synchronous network activity and subsequently increased synaptic strength between neurons. Furthermore, this synchronous network activity led to a significant increase in neuronal differentiation from the co-cultured neural precursor cells. When applied directly to precursor cells, glycine and Mg2+-free solution did not induce neuronal differentiation. Synaptic plasticity-induced neuronal differentiation of precursor cells was observed in the presence of GABAergic neurotransmission blockers but was dependent on NMDA-mediated Ca2+ influx. Most importantly, neuronal differentiation required the release of brain-derived neurotrophic factor (BDNF from the underlying substrate hippocampal neurons as well as TrkB receptor phosphorylation in precursor cells. This suggests that activity-dependent stem cell differentiation within the hippocampal network is mediated via synaptically evoked BDNF signaling.

  3. Neural networks

    International Nuclear Information System (INIS)

    Denby, Bruce; Lindsey, Clark; Lyons, Louis

    1992-01-01

    The 1980s saw a tremendous renewal of interest in 'neural' information processing systems, or 'artificial neural networks', among computer scientists and computational biologists studying cognition. Since then, the growth of interest in neural networks in high energy physics, fueled by the need for new information processing technologies for the next generation of high energy proton colliders, can only be described as explosive

  4. Laser microdissection of sensory organ precursor cells of Drosophila microchaetes.

    Directory of Open Access Journals (Sweden)

    Eulalie Buffin

    Full Text Available BACKGROUND: In Drosophila, each external sensory organ originates from the division of a unique precursor cell (the sensory organ precursor cell or SOP. Each SOP is specified from a cluster of equivalent cells, called a proneural cluster, all of them competent to become SOP. Although, it is well known how SOP cells are selected from proneural clusters, little is known about the downstream genes that are regulated during SOP fate specification. METHODOLOGY/PRINCIPAL FINDINGS: In order to better understand the mechanism involved in the specification of these precursor cells, we combined laser microdissection, toisolate SOP cells, with transcriptome analysis, to study their RNA profile. Using this procedure, we found that genes that exhibit a 2-fold or greater expression in SOPs versus epithelial cells were mainly associated with Gene Ontology (GO terms related with cell fate determination and sensory organ specification. Furthermore, we found that several genes such as pebbled/hindsight, scabrous, miranda, senseless, or cut, known to be expressed in SOP cells by independent procedures, are particularly detected in laser microdissected SOP cells rather than in epithelial cells. CONCLUSIONS/SIGNIFICANCE: These results confirm the feasibility and the specificity of our laser microdissection based procedure. We anticipate that this analysis will give new insight into the selection and specification of neural precursor cells.

  5. Trending analysis of precursor events

    International Nuclear Information System (INIS)

    Watanabe, Norio

    1998-01-01

    The Accident Sequence Precursor (ASP) Program of United States Nuclear Regulatory Commission (U.S.NRC) identifies and categorizes operational events at nuclear power plants in terms of the potential for core damage. The ASP analysis has been performed on yearly basis and the results have been published in the annual reports. This paper describes the trends in initiating events and dominant sequences for 459 precursors identified in the ASP Program during the 1969-94 period and also discusses a comparison with dominant sequences predicted in the past Probabilistic Risk Assessment (PRA) studies. These trends were examined for three time periods, 1969-81, 1984-87 and 1988-94. Although the different models had been used in the ASP analyses for these three periods, the distribution of precursors by dominant sequences show similar trends to each other. For example, the sequences involving loss of both main and auxiliary feedwater were identified in many PWR events and those involving loss of both high and low coolant injection were found in many BWR events. Also, it was found that these dominant sequences were comparable to those determined to be dominant in the predictions by the past PRAs. As well, a list of the 459 precursors identified are provided in Appendix, indicating initiating event types, unavailable systems, dominant sequences, conditional core damage probabilities, and so on. (author)

  6. Synthesis of labelled ecdysone precursors

    International Nuclear Information System (INIS)

    Haag, T.; Hetru, C.; Nakatani, Y.; Luu, B.; Meister, M.; Pichat, L.; Audinot, M.

    1985-01-01

    High specific activity tritiated 3β,14α-dihydroxy-5β-cholest-7-en-6-one, has been prepared using a precursor which permits rapid and easy labelling. This compound is converted to ecdysone under in vitro conditions by insect prothoracic glands, a well known site of ecdysone biosynthesis. (author)

  7. Leukemia inhibitory factor favours neurogenic differentiation of long-term propagated human midbrain precursor cells

    DEFF Research Database (Denmark)

    Andersen, Rikke K; Widmer, Hans R; Zimmer, Jens

    2009-01-01

    There is a lot of excitement about the potential use of multipotent neural stem cells for the treatment of neurodegenerative diseases. However, the strategy is compromised by the general loss of multipotency and ability to generate neurons after long-term in vitro propagation. In the present study......, human embryonic (5 weeks post-conception) ventral mesencephalic (VM) precursor cells were propagated as neural tissue-spheres (NTS) in epidermal growth factor (EGF; 20 ng/ml) and fibroblast growth factor 2 (FGF2; 20 ng/ml). After more than 325 days, the NTS were transferred to media containing either...... EGF+FGF2, EGF+FGF2+heparin or leukemia inhibitory factor (LIF; 10 ng/ml)+FGF2+heparin. Cultures were subsequently propagated for more than 180 days with NTS analyzed at various time-points. Our data show for the first time that human VM neural precursor cells can be long-term propagated as NTS...

  8. Neural Networks

    International Nuclear Information System (INIS)

    Smith, Patrick I.

    2003-01-01

    Physicists use large detectors to measure particles created in high-energy collisions at particle accelerators. These detectors typically produce signals indicating either where ionization occurs along the path of the particle, or where energy is deposited by the particle. The data produced by these signals is fed into pattern recognition programs to try to identify what particles were produced, and to measure the energy and direction of these particles. Ideally, there are many techniques used in this pattern recognition software. One technique, neural networks, is particularly suitable for identifying what type of particle caused by a set of energy deposits. Neural networks can derive meaning from complicated or imprecise data, extract patterns, and detect trends that are too complex to be noticed by either humans or other computer related processes. To assist in the advancement of this technology, Physicists use a tool kit to experiment with several neural network techniques. The goal of this research is interface a neural network tool kit into Java Analysis Studio (JAS3), an application that allows data to be analyzed from any experiment. As the final result, a physicist will have the ability to train, test, and implement a neural network with the desired output while using JAS3 to analyze the results or output. Before an implementation of a neural network can take place, a firm understanding of what a neural network is and how it works is beneficial. A neural network is an artificial representation of the human brain that tries to simulate the learning process [5]. It is also important to think of the word artificial in that definition as computer programs that use calculations during the learning process. In short, a neural network learns by representative examples. Perhaps the easiest way to describe the way neural networks learn is to explain how the human brain functions. The human brain contains billions of neural cells that are responsible for processing

  9. Evolvable synthetic neural system

    Science.gov (United States)

    Curtis, Steven A. (Inventor)

    2009-01-01

    An evolvable synthetic neural system includes an evolvable neural interface operably coupled to at least one neural basis function. Each neural basis function includes an evolvable neural interface operably coupled to a heuristic neural system to perform high-level functions and an autonomic neural system to perform low-level functions. In some embodiments, the evolvable synthetic neural system is operably coupled to one or more evolvable synthetic neural systems in a hierarchy.

  10. The Innate Lymphoid Cell Precursor.

    Science.gov (United States)

    Ishizuka, Isabel E; Constantinides, Michael G; Gudjonson, Herman; Bendelac, Albert

    2016-05-20

    The discovery of tissue-resident innate lymphoid cell populations effecting different forms of type 1, 2, and 3 immunity; tissue repair; and immune regulation has transformed our understanding of mucosal immunity and allergy. The emerging complexity of these populations along with compounding issues of redundancy and plasticity raise intriguing questions about their precise lineage relationship. Here we review advances in mapping the emergence of these lineages from early lymphoid precursors. We discuss the identification of a common innate lymphoid cell precursor characterized by transient expression of the transcription factor PLZF, and the lineage relationships of innate lymphoid cells with conventional natural killer cells and lymphoid tissue inducer cells. We also review the rapidly growing understanding of the network of transcription factors that direct the development of these lineages.

  11. Precursor polymer compositions comprising polybenzimidazole

    Science.gov (United States)

    Klaehn, John R.; Peterson, Eric S.; Orme, Christopher J.

    2015-07-14

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  12. Precursor incident program at EDF

    International Nuclear Information System (INIS)

    Fourest, B.; Maliverney, B.; Rozenholc, M.; Piovesan, C.

    1998-01-01

    The precursor program was started by EDF in 1994, after an investigation of the US NRC's Accident Sequence Precursor Program. Since then, reported operational events identified as Safety Outstanding Events have been analyzed whenever possible using probabilistic methods based on PSAs. Analysis provides an estimate of the remaining protection against core damage at the time the incident occurred. Measuring the incidents' severity enables to detect incidents important regarding safety. Moreover, the most efficient feedback actions can be derived from the main accident sequences identified through the analysis. Therefore, incident probabilistic analysis provides a way to assess priorities in terms of treatment and resource allocation, and so, to implement countermeasures preventing further occurrence and development of the most significant incidents. As some incidents cannot be analyzed using this method, probabilistic analysis can only be one among the methods used to assess the nuclear power plants' safety level. Nevertheless, it provides an interesting complement to classical methods of deterministic studies. (author)

  13. Application of Deep Learning to Detect Precursors of Tropical Cyclone

    Science.gov (United States)

    Matsuoka, D.; Nakano, M.; Sugiyama, D.; Uchida, S.

    2017-12-01

    Tropical cyclones (TCs) affect significant damage to human society. Predicting TC generation as soon as possible is important issue in both academic and social perspectives. In the present work, we investigate the probability of predicting TCs seven days prior using deep neural networks. The training data is produced from 30-year cloud resolving global atmospheric simulation (NICAM) with 14 km horizontal resolution (Kodama et al., 2015). We employed a TCs tracking algorithm (Sugi et al., 2002; Nakano et al., 2015) to NICAM simulation data in order to generate supervised cloud images (horizontal sizes are 800-1,000km). We generate approximately one million images of "TCs (include their precursors)" and "not TCs (low pressure clouds)". We generate ten types of image classifier based on 2-dimensional convolutional neural network, includes four convolutional layers, three pooling layers and two fully connected layers. The final predicted results are obtained by these ensemble mean values. Generated classifiers are applied to untrained global simulation data (four million test images). As a result, we succeeded in predicting the precursors of TCs seven and five days before their formation with a Recall of 88.6% and 89.6% (Precision is 11.4%), respectively.

  14. Stimulation of neural differentiation in human bone marrow mesenchymal stem cells by extremely low-frequency electromagnetic fields incorporated with MNPs.

    Science.gov (United States)

    Choi, Yun-Kyong; Lee, Dong Heon; Seo, Young-Kwon; Jung, Hyun; Park, Jung-Keug; Cho, Hyunjin

    2014-10-01

    Human bone marrow-derived mesenchymal stem cells (hBM-MSCs) have been investigated as a new cell-therapeutic solution due to their capacity that could differentiate into neural-like cells. Extremely low-frequency electromagnetic fields (ELF-EMFs) therapy has emerged as a novel technique, using mechanical stimulus to differentiate hBM-MSCs and significantly enhance neuronal differentiation to affect cellular and molecular reactions. Magnetic iron oxide (Fe3O4) nanoparticles (MNPs) have recently achieved widespread use for biomedical applications and polyethylene glycol (PEG)-labeled nanoparticles are used to increase their circulation time, aqueous solubility, biocompatibility, and nonspecific cellular uptake as well as to decrease immunogenicity. Many studies have used MNP-labeled cells for differentiation, but there have been no reports of MNP-labeled neural differentiation combined with EMFs. In this study, synthesized PEG-phospholipid encapsulated magnetite (Fe3O4) nanoparticles are used on hBM-MSCs to improve their intracellular uptake. The PEGylated nanoparticles were exposed to the cells under 50 Hz of EMFs to improve neural differentiation. First, we measured cell viability and intracellular iron content in hBM-MSCs after treatment with MNPs. Analysis was conducted by RT-PCR, and immunohistological analysis using neural cell type-specific genes and antibodies after exposure to 50 Hz electromagnetic fields. These results suggest that electromagnetic fields enhance neural differentiation in hBM-MSCs incorporated with MNPs and would be an effective method for differentiating neural cells.

  15. Radon as an earthquake precursor

    International Nuclear Information System (INIS)

    Planinic, J.; Radolic, V.; Vukovic, B.

    2004-01-01

    Radon concentrations in soil gas were continuously measured by the LR-115 nuclear track detectors during a four-year period. Seismic activities, as well as barometric pressure, rainfall and air temperature were also observed. The influence of meteorological parameters on temporal radon variations was investigated, and a respective equation of the multiple regression was derived. The earthquakes with magnitude ≥3 at epicentral distances ≤200 km were recognized by means of radon anomaly. Empirical equations between earthquake magnitude, epicentral distance and precursor time were examined, and respective constants were determined

  16. Radon as an earthquake precursor

    Energy Technology Data Exchange (ETDEWEB)

    Planinic, J. E-mail: planinic@pedos.hr; Radolic, V.; Vukovic, B

    2004-09-11

    Radon concentrations in soil gas were continuously measured by the LR-115 nuclear track detectors during a four-year period. Seismic activities, as well as barometric pressure, rainfall and air temperature were also observed. The influence of meteorological parameters on temporal radon variations was investigated, and a respective equation of the multiple regression was derived. The earthquakes with magnitude {>=}3 at epicentral distances {<=}200 km were recognized by means of radon anomaly. Empirical equations between earthquake magnitude, epicentral distance and precursor time were examined, and respective constants were determined.

  17. Fluorescing macerals from wood precursors

    Energy Technology Data Exchange (ETDEWEB)

    Stout, S A; Bensley, D F

    1987-01-01

    A preliminary investigation into the origin of wood-derived macerals has established the existence of autofluorescent maceral precursors in the secondary xylem of swamp-inhabiting plant species. The optical character and fluorescent properties of microtomed thin-sections of modern woods from the Florida Everglades and Okefenokee Swamp, Georgia are compared to the character and properties of their peatified equivalents from various Everglades and Okefenokee peat horizons and their lignitic equivalents from the Brandon lignite of Vermont and the Trail Ridge lignitic peat from northern Florida. The inherent fluorescence of woody cell walls is believed to be caused by lignin though other cell wall components may contribute. The fluorescence spectra for several wood and cell types had a ..gamma../sub m//sub a//sub x/ of 452 nm and Q value of 0.00. The color as observed in blue light and the spectral geometry as measured in UV light of peatified and lignitic woody cell walls (potential textinites) may change progressively during early coalification. Cell wall-derived maceral material is shown to maintain its fluorescing properties after being converted to a structureless material, perhaps a corpohuminite or humodetrinite precursor. Fluorescing xylem cell contents, such as condensed tannins or essential oils, can maintain the fluorescent character through early coalification. Xylem cell walls and xylem cell contents are shown to provide fluorescing progenitor materials which would not require subsequent infusion with 'lipid' materials to account for their fluorescence as phytoclast material or as macerals in coal. 35 references.

  18. Precursor processes of human self-initiated action.

    Science.gov (United States)

    Khalighinejad, Nima; Schurger, Aaron; Desantis, Andrea; Zmigrod, Leor; Haggard, Patrick

    2018-01-15

    A gradual buildup of electrical potential over motor areas precedes self-initiated movements. Recently, such "readiness potentials" (RPs) were attributed to stochastic fluctuations in neural activity. We developed a new experimental paradigm that operationalized self-initiated actions as endogenous 'skip' responses while waiting for target stimuli in a perceptual decision task. We compared these to a block of trials where participants could not choose when to skip, but were instead instructed to skip. Frequency and timing of motor action were therefore balanced across blocks, so that conditions differed only in how the timing of skip decisions was generated. We reasoned that across-trial variability of EEG could carry as much information about the source of skip decisions as the mean RP. EEG variability decreased more markedly prior to self-initiated compared to externally-triggered skip actions. This convergence suggests a consistent preparatory process prior to self-initiated action. A leaky stochastic accumulator model could reproduce this convergence given the additional assumption of a systematic decrease in input noise prior to self-initiated actions. Our results may provide a novel neurophysiological perspective on the topical debate regarding whether self-initiated actions arise from a deterministic neurocognitive process, or from neural stochasticity. We suggest that the key precursor of self-initiated action may manifest as a reduction in neural noise. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  19. Neural Networks

    Directory of Open Access Journals (Sweden)

    Schwindling Jerome

    2010-04-01

    Full Text Available This course presents an overview of the concepts of the neural networks and their aplication in the framework of High energy physics analyses. After a brief introduction on the concept of neural networks, the concept is explained in the frame of neuro-biology, introducing the concept of multi-layer perceptron, learning and their use as data classifer. The concept is then presented in a second part using in more details the mathematical approach focussing on typical use cases faced in particle physics. Finally, the last part presents the best way to use such statistical tools in view of event classifers, putting the emphasis on the setup of the multi-layer perceptron. The full article (15 p. corresponding to this lecture is written in french and is provided in the proceedings of the book SOS 2008.

  20. A cell junction pathology of neural stem cells leads to abnormal neurogenesis and hydrocephalus

    NARCIS (Netherlands)

    Rodríguez, Esteban M; Guerra, María M; Vío, Karin; González, César; Ortloff, Alexander; Bátiz, Luis F; Rodríguez, Sara; Jara, María C; Muñoz, Rosa I; Ortega, Eduardo; Jaque, Jaime; Guerra, Francisco; Sival, Deborah A; den Dunnen, Wilfred F A; Jiménez, Antonio J; Domínguez-Pinos, María D; Pérez-Fígares, José M; McAllister, James P; Johanson, Conrad

    2012-01-01

    Most cells of the developing mammalian brain derive from the ventricular (VZ) and the subventricular (SVZ) zones. The VZ is formed by the multipotent radial glia/neural stem cells (NSCs) while the SVZ harbors the rapidly proliferative neural precursor cells (NPCs). Evidence from human and animal

  1. Wittgenstein running: neural mechanisms of collective intentionality and we-mode.

    Science.gov (United States)

    Becchio, Cristina; Bertone, Cesare

    2004-03-01

    In this paper we discuss the problem of the neural conditions of shared attitudes and intentions: which neural mechanisms underlie "we-mode" processes or serve as precursors to such processes? Neurophysiological and neuropsychological evidence suggests that in different areas of the brain neural representations are shared by several individuals. This situation, on the one hand, creates a potential problem for correct attribution. On the other hand, it may provide the conditions for shared attitudes and intentions.

  2. Rapid synthesis of macrocycles from diol precursors

    DEFF Research Database (Denmark)

    Wingstrand, Magnus; Madsen, Charlotte Marie; Clausen, Mads Hartvig

    2009-01-01

    A method for the formation of synthetic macrocycles with different ring sizes from diols is presented. Reacting a simple diol precursor with electrophilic reagents leads to a cyclic carbonate, sulfite or phosphate in a single step in 25-60% yield. Converting the cyclization precursor to a bis-ele...

  3. Precursors in photonic crystals - art. no. 618218

    NARCIS (Netherlands)

    Uitham, R.; Hoenders, B. J.; DeLaRue, RM; Viktorovitch, P; Lopez, C; Midrio, M

    2006-01-01

    We derive the Sommerfeld precursor and present the first calculations for the Brillouin precursor that result from the transmission of a pulse through a photonic crystal. The photonic crystal is modelled by a one-dimensional N-layer medium and the pulse is a generic electromagnetic plane wave packet

  4. The Sommerfeld precursor in photonic crystals

    NARCIS (Netherlands)

    Uitham, R; Hoenders, BJ

    2006-01-01

    We calculate the Sommerfeld precursor that results after transmission of a generic electromagnetic plane wave pulse with transverse electric polarization, through a one-dimensional rectangular N-layer photonic crystal with two slabs per layer. The shape of this precursor equals the shape of the

  5. Bioinspired magnetite synthesis via solid precursor phases

    NARCIS (Netherlands)

    Lenders, J.J.M.; Mirabello, G.; Sommerdijk, N.A.J.M.

    2016-01-01

    Living organisms often exploit solid but poorly ordered mineral phases as precursors in the biomineralization of their inorganic body parts. Generally speaking, such precursor-based approaches allow the organisms-without the need of high supersaturation levels-to accumulate significant quantities of

  6. The interrelationships of mathematical precursors in kindergarten.

    Science.gov (United States)

    Cirino, Paul T

    2011-04-01

    This study evaluated the interrelations among cognitive precursors across quantitative, linguistic, and spatial attention domains that have been implicated for math achievement in young children. The dimensionality of the quantity precursors was evaluated in 286 kindergarteners via latent variable techniques, and the contribution of precursors from each domain was established for small sums addition. Results showed a five-factor structure for the quantity precursors, with the major distinction being between nonsymbolic and symbolic tasks. The overall model demonstrated good fit and strong predictive power (R(2)=55%) for addition number combinations. Linguistic and spatial attention domains showed indirect relationships with outcomes, with their effects mediated by symbolic quantity measures. These results have implications for the measurement of mathematical precursors and yield promise for predicting future math performance. Copyright © 2010 Elsevier Inc. All rights reserved.

  7. Microparticle Shedding from Neural Progenitor Cells and Vascular Compartment Cells Is Increased in Ischemic Stroke.

    Science.gov (United States)

    Chiva-Blanch, Gemma; Suades, Rosa; Crespo, Javier; Peña, Esther; Padró, Teresa; Jiménez-Xarrié, Elena; Martí-Fàbregas, Joan; Badimon, Lina

    2016-01-01

    Ischemic stroke has shown to induce platelet and endothelial microparticle shedding, but whether stroke induces microparticle shedding from additional blood and vascular compartment cells is unclear. Neural precursor cells have been shown to replace dying neurons at sites of brain injury; however, if neural precursor cell activation is associated to microparticle shedding, and whether this activation is maintained at long term and associates to stroke type and severity remains unknown. We analyzed neural precursor cells and blood and vascular compartment cells microparticle shedding after an acute ischemic stroke. Forty-four patients were included in the study within the first 48h after the onset of stroke. The cerebral lesion size was evaluated at 3-7 days of the stroke. Circulating microparticles from neural precursor cells and blood and vascular compartment cells (platelets, endothelial cells, erythrocytes, leukocytes, lymphocytes, monocytes and smooth muscle cells) were analyzed by flow cytometry at the onset of stroke and at 7 and 90 days. Forty-four age-matched high cardiovascular risk subjects without documented vascular disease were used as controls. Compared to high cardiovascular risk controls, patients showed higher number of neural precursor cell- and all blood and vascular compartment cell-derived microparticles at the onset of stroke, and after 7 and 90 days. At 90 days, neural precursor cell-derived microparticles decreased and smooth muscle cell-derived microparticles increased compared to levels at the onset of stroke, but only in those patients with the highest stroke-induced cerebral lesions. Stroke increases blood and vascular compartment cell and neural precursor cell microparticle shedding, an effect that is chronically maintained up to 90 days after the ischemic event. These results show that stroke induces a generalized blood and vascular cell activation and the initiation of neuronal cell repair process after stroke. Larger cerebral lesions

  8. Microparticle Shedding from Neural Progenitor Cells and Vascular Compartment Cells Is Increased in Ischemic Stroke.

    Directory of Open Access Journals (Sweden)

    Gemma Chiva-Blanch

    Full Text Available Ischemic stroke has shown to induce platelet and endothelial microparticle shedding, but whether stroke induces microparticle shedding from additional blood and vascular compartment cells is unclear. Neural precursor cells have been shown to replace dying neurons at sites of brain injury; however, if neural precursor cell activation is associated to microparticle shedding, and whether this activation is maintained at long term and associates to stroke type and severity remains unknown. We analyzed neural precursor cells and blood and vascular compartment cells microparticle shedding after an acute ischemic stroke.Forty-four patients were included in the study within the first 48h after the onset of stroke. The cerebral lesion size was evaluated at 3-7 days of the stroke. Circulating microparticles from neural precursor cells and blood and vascular compartment cells (platelets, endothelial cells, erythrocytes, leukocytes, lymphocytes, monocytes and smooth muscle cells were analyzed by flow cytometry at the onset of stroke and at 7 and 90 days. Forty-four age-matched high cardiovascular risk subjects without documented vascular disease were used as controls.Compared to high cardiovascular risk controls, patients showed higher number of neural precursor cell- and all blood and vascular compartment cell-derived microparticles at the onset of stroke, and after 7 and 90 days. At 90 days, neural precursor cell-derived microparticles decreased and smooth muscle cell-derived microparticles increased compared to levels at the onset of stroke, but only in those patients with the highest stroke-induced cerebral lesions.Stroke increases blood and vascular compartment cell and neural precursor cell microparticle shedding, an effect that is chronically maintained up to 90 days after the ischemic event. These results show that stroke induces a generalized blood and vascular cell activation and the initiation of neuronal cell repair process after stroke. Larger

  9. Electrophysiological precursors of social conformity

    Science.gov (United States)

    Rieskamp, Jörg; Tugin, Sergey; Ossadtchi, Alexey; Krutitskaya, Janina; Klucharev, Vasily

    2013-01-01

    Humans often change their beliefs or behavior due to the behavior or opinions of others. This study explored, with the use of human event-related potentials (ERPs), whether social conformity is based on a general performance-monitoring mechanism. We tested the hypothesis that conflicts with a normative group opinion evoke a feedback-related negativity (FRN) often associated with performance monitoring and subsequent adjustment of behavior. The experimental results show that individual judgments of facial attractiveness were adjusted in line with a normative group opinion. A mismatch between individual and group opinions triggered a frontocentral negative deflection with the maximum at 200 ms, similar to FRN. Overall, a conflict with a normative group opinion triggered a cascade of neuronal responses: from an earlier FRN response reflecting a conflict with the normative opinion to a later ERP component (peaking at 380 ms) reflecting a conforming behavioral adjustment. These results add to the growing literature on neuronal mechanisms of social influence by disentangling the conflict-monitoring signal in response to the perceived violation of social norms and the neural signal of a conforming behavioral adjustment. PMID:22683703

  10. Biochemical Removal of HAP Precursors From Coal

    International Nuclear Information System (INIS)

    Olson, G.; Tucker, L.; Richards, J.

    1997-07-01

    This project addresses DOE's interest in advanced concepts for controlling emissions of air toxics from coal-fired utility boilers. We are determining the feasibility of developing a biochemical process for the precombustion removal of substantial percentages of 13 inorganic hazardous air pollutant (HAP) precursors from coal. These HAP precursors are Sb, As, Be, Cd, Cr, Cl, Co, F, Pb, Hg, Mn, Ni, and Se. Although rapid physical coal cleaning is done routinely in preparation plants, biochemical processes for removal of HAP precursors from coal potentially offer advantages of deeper cleaning, more specificity, and less coal loss. Compared to chemical processes for coal cleaning, biochemical processes potentially offer lower costs and milder process conditions. Pyrite oxidizing bacteria, most notably Thiobacillusferrooxidans, are being evaluated in this project for their ability to remove HAP precursors from U.S. coals

  11. Progress in molecular precursors for electronic materials

    Energy Technology Data Exchange (ETDEWEB)

    Buhro, W.E. [Washington Univ., St. Louis, MO (United States)

    1996-09-01

    Molecular-precursor chemistry provides an essential underpinning to all electronic-materials technologies, including photovoltaics and related areas of direct interest to the DOE. Materials synthesis and processing is a rapidly developing field in which advances in molecular precursors are playing a major role. This article surveys selected recent research examples that define the exciting current directions in molecular-precursor science. These directions include growth of increasingly complex structures and stoichiometries, surface-selective growth, kinetic growth of metastable materials, growth of size-controlled quantum dots and quantum-dot arrays, and growth at progressively lower temperatures. Continued progress in molecular-precursor chemistry will afford precise control over the crystal structures, nanostructures, and microstructures of electronic materials.

  12. Biochemical Removal of HAP Precursors From Coal

    Energy Technology Data Exchange (ETDEWEB)

    Olson, G.; Tucker, L.; Richards, J.

    1997-07-01

    This project addresses DOE`s interest in advanced concepts for controlling emissions of air toxics from coal-fired utility boilers. We are determining the feasibility of developing a biochemical process for the precombustion removal of substantial percentages of 13 inorganic hazardous air pollutant (HAP) precursors from coal. These HAP precursors are Sb, As, Be, Cd, Cr, Cl, Co, F, Pb, Hg, Mn, Ni, and Se. Although rapid physical coal cleaning is done routinely in preparation plants, biochemical processes for removal of HAP precursors from coal potentially offer advantages of deeper cleaning, more specificity, and less coal loss. Compared to chemical processes for coal cleaning, biochemical processes potentially offer lower costs and milder process conditions. Pyrite oxidizing bacteria, most notably Thiobacillusferrooxidans, are being evaluated in this project for their ability to remove HAP precursors from U.S. coals.

  13. Probabilistic precursor analysis - an application of PSA

    International Nuclear Information System (INIS)

    Hari Prasad, M.; Gopika, V.; Sanyasi Rao, V.V.S.; Vaze, K.K.

    2011-01-01

    Incidents are inevitably part of the operational life of any complex industrial facility, and it is hard to predict how various contributing factors combine to cause the outcome. However, it should be possible to detect the existence of latent conditions that, together with the triggering failure(s), result in abnormal events. These incidents are called precursors. Precursor study, by definition, focuses on how a particular event might have adversely developed. This paper focuses on the events which can be analyzed to assess their potential to develop into core damage situation and looks into extending Probabilistic Safety Assessment techniques to precursor studies and explains the benefits through a typical case study. A preliminary probabilistic precursor analysis has been carried out for a typical NPP. The major advantages of this approach are the strong potential for augmenting event analysis which is currently carried out purely on deterministic basis. (author)

  14. nanoparticles synthesized by citrate precursor m

    African Journals Online (AJOL)

    user

    (M=Co, Cu) nanoparticles synthesized by citrate precursor method ... The structural characterization was carried out using an X-ray Diffractometer (Rikagu Miniflex, Japan) ..... His current area of interest includes magnetic nanomaterials.

  15. Planar half-cell shaped precursor body

    DEFF Research Database (Denmark)

    2015-01-01

    The invention relates to a half-cell shaped precursor body of either anode type or cathode type, the half-cell shaped precursor body being prepared to be free sintered to form a sintered or pre-sintered half-cell being adapted to be stacked in a solid oxide fuel cell stack. The obtained half......-cell has an improved planar shape, which remains planar also after a sintering process and during temperature fluctuations....

  16. Radiochemical Means of Investigating Delayed Neutron Precursors

    International Nuclear Information System (INIS)

    Marmol, P. del

    1968-01-01

    Fast radiochemical methods used now for the determination of delayed neutron precursors are classified and reviewed: precipitations, solvent extractions, range experiments, milking, gas sweeping, isotopic and ion exchange, hot atom reactions and diffusion loss. Advantages and limitations of irradiation systems with respect to fast separations are discussed: external beams which allow faster separations only have low neutron fluxes, internal beams which are mostly fit for gaseous reactions; and rabbits for solution irradiations. Future prospects of radiochemical procedures are presented; among these, studies should be mostly oriented towards gaseous reactions which offer possibilities of isolating very short-lived delayed neutron precursors. Chemical procedures for delayed neutron precursor detection are compared with mass spectrometric and isotope separator techniques; it is concluded that the methods are complementary. (author)

  17. Radiochemical Means of Investigating Delayed Neutron Precursors

    International Nuclear Information System (INIS)

    Marmol, P. del

    1968-01-01

    Fast radiochemical methods used now for the determination of delayed neutron precursors are classified and reviewed: precipitations, solvent extractions, range experiments, milking, gas sweeping, isotopic and ion exchange, hot-atom reactions and diffusion loss. Advantages and limitations of irradiation systems with respect to fast separations are discussed: external beams which allow faster separations only have low neutron fluxes, internal beams which are mostly fit for gaseous reactions; and rabbits for solution irradiations. Future prospects of radiochemical procedures are presented; among these, studies should be mostly oriented towards gaseous reactions which offer possibilities of isolating very short-lived delayed neutron precursors. Chemical procedures for delayed neutron precursor detection are compared with mass spectrometric and isotope-separator techniques; it is concluded that the methods are complementary. (author)

  18. Annotation of novel neuropeptide precursors in the migratory locust based on transcript screening of a public EST database and mass spectrometry

    Directory of Open Access Journals (Sweden)

    De Loof Arnold

    2006-08-01

    Full Text Available Abstract Background For holometabolous insects there has been an explosion of proteomic and peptidomic information thanks to large genome sequencing projects. Heterometabolous insects, although comprising many important species, have been far less studied. The migratory locust Locusta migratoria, a heterometabolous insect, is one of the most infamous agricultural pests. They undergo a well-known and profound phase transition from the relatively harmless solitary form to a ferocious gregarious form. The underlying regulatory mechanisms of this phase transition are not fully understood, but it is undoubtedly that neuropeptides are involved. However, neuropeptide research in locusts is hampered by the absence of genomic information. Results Recently, EST (Expressed Sequence Tag databases from Locusta migratoria were constructed. Using bioinformatical tools, we searched these EST databases specifically for neuropeptide precursors. Based on known locust neuropeptide sequences, we confirmed the sequence of several previously identified neuropeptide precursors (i.e. pacifastin-related peptides, which consolidated our method. In addition, we found two novel neuroparsin precursors and annotated the hitherto unknown tachykinin precursor. Besides one of the known tachykinin peptides, this EST contained an additional tachykinin-like sequence. Using neuropeptide precursors from Drosophila melanogaster as a query, we succeeded in annotating the Locusta neuropeptide F, allatostatin-C and ecdysis-triggering hormone precursor, which until now had not been identified in locusts or in any other heterometabolous insect. For the tachykinin precursor, the ecdysis-triggering hormone precursor and the allatostatin-C precursor, translation of the predicted neuropeptides in neural tissues was confirmed with mass spectrometric techniques. Conclusion In this study we describe the annotation of 6 novel neuropeptide precursors and the neuropeptides they encode from the

  19. Precursors prior to type IIn supernova explosions are common: Precursor rates, properties, and correlations

    Energy Technology Data Exchange (ETDEWEB)

    Ofek, Eran O.; Steinbok, Aviram; Arcavi, Iair; Gal-Yam, Avishay; Tal, David; Ben-Ami, Sagi; Yaron, Ofer [Benoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel); Sullivan, Mark [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Shaviv, Nir J. [Racah Institute of Physics, The Hebrew University, 91904 Jerusalem (Israel); Kulkarni, Shrinivas R. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Nugent, Peter E. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Kasliwal, Mansi M. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Cenko, S. Bradley [Astrophysics Science Division, NASA/Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Laher, Russ; Surace, Jason [Spitzer Science Center, California Institute of Technology, M/S 314-6, Pasadena, CA 91125 (United States); Bloom, Joshua S.; Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Silverman, Jeffrey M. [Department of Astronomy, University of Texas, Austin, TX 78712 (United States)

    2014-07-10

    There is a growing number of Type IIn supernovae (SNe) which present an outburst prior to their presumably final explosion. These precursors may affect the SN display, and are likely related to poorly charted phenomena in the final stages of stellar evolution. By coadding Palomar Transient Factory (PTF) images taken prior to the explosion, here we present a search for precursors in a sample of 16 Type IIn SNe. We find five SNe IIn that likely have at least one possible precursor event (PTF 10bjb, SN 2010mc, PTF 10weh, SN 2011ht, and PTF 12cxj), three of which are reported here for the first time. For each SN we calculate the control time. We find that precursor events among SNe IIn are common: at the one-sided 99% confidence level, >50% of SNe IIn have at least one pre-explosion outburst that is brighter than 3 × 10{sup 7} L{sub ☉} taking place up to 1/3 yr prior to the SN explosion. The average rate of such precursor events during the year prior to the SN explosion is likely ≳ 1 yr{sup –1}, and fainter precursors are possibly even more common. Ignoring the two weakest precursors in our sample, the precursors rate we find is still on the order of one per year. We also find possible correlations between the integrated luminosity of the precursor and the SN total radiated energy, peak luminosity, and rise time. These correlations are expected if the precursors are mass-ejection events, and the early-time light curve of these SNe is powered by interaction of the SN shock and ejecta with optically thick circumstellar material.

  20. Onset of Spinal Cord Astrocyte Precursor Emigration from the Ventricular Zone Involves the Zeb1 Transcription Factor

    Directory of Open Access Journals (Sweden)

    David Ohayon

    2016-11-01

    Full Text Available During spinal cord development, astrocyte precursors arise from neuroepithelial progenitors, delaminate from the ventricular zone, and migrate toward their final locations where they differentiate. Although the mechanisms underlying their early specification and late differentiation are being deciphered, less is known about the temporal control of their migration. Here, we show that the epithelial-mesenchymal transition regulator Zeb1 is expressed in glial precursors and report that loss of Zeb1 function specifically delays the onset of astrocyte precursor delamination from the ventricular zone, correlating with transient deregulation of the adhesion protein Cadherin-1. Consequently, astrocyte precursor invasion into the Zeb1−/− mutant white matter is delayed, and induction of their differentiation is postponed. These findings illustrate how fine regulation of adhesive properties influences the onset of neural precursor migration and further support the notion that duration of exposure of migrating astrocyte precursors to environmental cues and/or their correct positioning influence the timing of their differentiation.

  1. Morphological neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, G.X.; Sussner, P. [Univ. of Florida, Gainesville, FL (United States)

    1996-12-31

    The theory of artificial neural networks has been successfully applied to a wide variety of pattern recognition problems. In this theory, the first step in computing the next state of a neuron or in performing the next layer neural network computation involves the linear operation of multiplying neural values by their synaptic strengths and adding the results. Thresholding usually follows the linear operation in order to provide for nonlinearity of the network. In this paper we introduce a novel class of neural networks, called morphological neural networks, in which the operations of multiplication and addition are replaced by addition and maximum (or minimum), respectively. By taking the maximum (or minimum) of sums instead of the sum of products, morphological network computation is nonlinear before thresholding. As a consequence, the properties of morphological neural networks are drastically different than those of traditional neural network models. In this paper we consider some of these differences and provide some particular examples of morphological neural network.

  2. Neural Tube Defects

    Science.gov (United States)

    Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the ... that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In ...

  3. Report on Fukushima Daiichi NPP precursor events

    International Nuclear Information System (INIS)

    2014-01-01

    The main questions to be answered by this report were: The Fukushima Daiichi NPP accident, could it have been prevented? If there is a next severe accident, may it be prevented? To answer the first question, the report addressed several aspects. First, the report investigated whether precursors to the Fukushima Daiichi NPP accident existed in the operating experience; second, the reasons why these precursors did not evolve into a severe accident. Third, whether lessons learned from these precursor events were adequately considered by member countries; and finally, if the operating experience feedback system needs to be improved, based on the previous analysis. To address the second question which is much more challenging, the report considered precursor events identified through a search and analysis of the IRS database and also precursors events based on risk significance. Both methods can point out areas where further work may be needed, even if it depends heavily on design and site-specific factors. From the operating experience side, more efforts are needed to ensure timely and full implementation of lessons learnt from precursor events. Concerning risk considerations, a combined use of risk precursors and operating experience may drive to effective changes to plants to reduce risk. The report also contains a short description and evaluation of selected precursors that are related to the course of the Fukushima Daiichi NPP accident. The report addresses the question whether operating experience feedback can be effectively used to identify plant vulnerabilities and minimize potential for severe core damage accidents. Based on several of the precursor events national or international in-depth evaluations were started. The vulnerability of NPPs due to external and internal flooding has clearly been addressed. In addition to the IRS based investigation, the WGRISK was asked to identify important precursor events based on risk significance. These precursors have

  4. CD44-positive cells are candidates for astrocyte precursor cells in developing mouse cerebellum.

    Science.gov (United States)

    Cai, Na; Kurachi, Masashi; Shibasaki, Koji; Okano-Uchida, Takayuki; Ishizaki, Yasuki

    2012-03-01

    Neural stem cells are generally considered to be committed to becoming precursor cells before terminally differentiating into either neurons or glial cells during neural development. Neuronal and oligodendrocyte precursor cells have been identified in several areas in the murine central nervous system. The presence of astrocyte precursor cells (APCs) is not so well understood. The present study provides several lines of evidence that CD44-positive cells are APCs in the early postnatal mouse cerebellum. In developing mouse cerebellum, CD44-positive cells, mostly located in the white matter, were positive for the markers of the astrocyte lineage, but negative for the markers of mature astrocytes. CD44-positive cells were purified from postnatal cerebellum by fluorescence-activated cell sorting and characterized in vitro. In the absence of any signaling molecule, many cells died by apoptosis. The surviving cells gradually expressed glial fibrillary acidic protein, a marker for mature astrocytes, indicating that differentiation into mature astrocytes is the default program for these cells. The cells produced no neurospheres nor neurons nor oligodendrocytes under any condition examined, indicating these cells are not neural stem cells. Leukemia inhibitory factor greatly promoted astrocytic differentiation of CD44-positive cells, whereas bone morphogenetic protein 4 (BMP4) did not. Fibroblast growth factor-2 was a potent mitogen for these cells, but was insufficient for survival. BMP4 inhibited activation of caspase-3 and greatly promoted survival, suggesting a novel role for BMP4 in the control of development of astrocytes in cerebellum. We isolated and characterized only CD44 strongly positive large cells and discarded small and/or CD44 weakly positive cells in this study. Further studies are necessary to characterize these cells to help determine whether CD44 is a selective and specific marker for APCs in the developing mouse cerebellum. In conclusion, we succeeded in

  5. Sol-gel precursors and products thereof

    Science.gov (United States)

    Warren, Scott C.; DiSalvo, Jr., Francis J.; Weisner, Ulrich B.

    2017-02-14

    The present invention provides a generalizable single-source sol-gel precursor capable of introducing a wide range of functionalities to metal oxides such as silica. The sol-gel precursor facilitates a one-molecule, one-step approach to the synthesis of metal-silica hybrids with combinations of biological, catalytic, magnetic, and optical functionalities. The single-source precursor also provides a flexible route for simultaneously incorporating functional species of many different types. The ligands employed for functionalizing the metal oxides are derived from a library of amino acids, hydroxy acids, or peptides and a silicon alkoxide, allowing many biological functionalities to be built into silica hybrids. The ligands can coordinate with a wide range of metals via a carboxylic acid, thereby allowing direct incorporation of inorganic functionalities from across the periodic table. Using the single-source precursor a wide range of functionalized nanostructures such as monolith structures, mesostructures, multiple metal gradient mesostructures and Stober-type nanoparticles can be synthesized. ##STR00001##

  6. Precursor Dependent Structural Properties and Antibacterial Activity ...

    Indian Academy of Sciences (India)

    71

    10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30 ... absorption spectroscopy, Scanning electron microscopy (SEM) and Zeta ... The antibacterial activity of the synthesized CuO were studied against human .... Sample d : Copper oxide synthesized with cupric sulphate as precursor ...... Chem.4 86.

  7. Biochemical Removal of HAP Precursors from Coal

    Energy Technology Data Exchange (ETDEWEB)

    Olson, Gregory J

    1997-05-12

    Column biooxidation tests with Kentucky coal confirmed results of earlier shake flask tests showing significant removal from the coal of arsenic, selenium, cobalt, manganese, nickel and cadmium. Rates of pyrite biooxidation in Kentucky coal were only slightly more than half the rates found previously for Indiana and Pittsburgh coals. Removal of pyrite from Pittsburgh coal by ferric ion oxidation slows markedly as ferrous ions accumulate in solution, requiring maintenance of high redox potentials in processes designed for removal of pyrite and hazardous air pollutant (HAP) precursors by circulation of ferric solutions through coal. The pyrite oxidation rates obtained in these tests were used by Unifield Engineering to support the conceptual designs for alternative pyrite and HAP precursor bioleaching processes for the phase 2 pilot plant. Thermophilic microorganisms were tested to determine if mercury could be mobilized from coal under elevated growth temperatures. There was no evidence for mercury removal from coal under these conditions. However, the activity of the organisms may have liberated mercury physically. It is also possible that the organisms dissolved mercury and it readsorbed to the clay preferentially. Both of these possibilities are undergoing further testing. The Idaho National Engineering and Environmental Laboratory's (INEEL) slurry column reactor was operated and several batches of feed coal, product coal, waste solids and leach solutions were submitted to LBL for HAP precursor analysis. Results to date indicate significant removal of mercury, arsenic and other HAP precursors in the combined physical-biological process.

  8. Neural electrical activity and neural network growth.

    Science.gov (United States)

    Gafarov, F M

    2018-05-01

    The development of central and peripheral neural system depends in part on the emergence of the correct functional connectivity in its input and output pathways. Now it is generally accepted that molecular factors guide neurons to establish a primary scaffold that undergoes activity-dependent refinement for building a fully functional circuit. However, a number of experimental results obtained recently shows that the neuronal electrical activity plays an important role in the establishing of initial interneuronal connections. Nevertheless, these processes are rather difficult to study experimentally, due to the absence of theoretical description and quantitative parameters for estimation of the neuronal activity influence on growth in neural networks. In this work we propose a general framework for a theoretical description of the activity-dependent neural network growth. The theoretical description incorporates a closed-loop growth model in which the neural activity can affect neurite outgrowth, which in turn can affect neural activity. We carried out the detailed quantitative analysis of spatiotemporal activity patterns and studied the relationship between individual cells and the network as a whole to explore the relationship between developing connectivity and activity patterns. The model, developed in this work will allow us to develop new experimental techniques for studying and quantifying the influence of the neuronal activity on growth processes in neural networks and may lead to a novel techniques for constructing large-scale neural networks by self-organization. Copyright © 2018 Elsevier Ltd. All rights reserved.

  9. Induction of Skin-Derived Precursor Cells from Human Induced Pluripotent Stem Cells.

    Science.gov (United States)

    Sugiyama-Nakagiri, Yoriko; Fujimura, Tsutomu; Moriwaki, Shigeru

    2016-01-01

    The generation of full thickness human skin from dissociated cells is an attractive approach not only for treating skin diseases, but also for treating many systemic disorders. However, it is currently not possible to obtain an unlimited number of skin dermal cells. The goal of this study was to develop a procedure to produce skin dermal stem cells from induced pluripotent stem cells (iPSCs). Skin-derived precursor cells (SKPs) were isolated as adult dermal precursors that could differentiate into both neural and mesodermal progenies and could reconstitute the dermis. Thus, we attempted to generate SKPs from iPSCs that could reconstitute the skin dermis. Human iPSCs were initially cultured with recombinant noggin and SB431542, an inhibitor of activin/nodal and TGFβ signaling, to induce neural crest progenitor cells. Those cells were then treated with SKP medium that included CHIR99021, a WNT signal activator. The induction efficacy from neural crest progenitor cells to SKPs was more than 97%. No other modifiers tested were able to induce those cells. Those human iPSC-derived SKPs (hiPSC-SKPs) showed a similar gene expression signature to SKPs isolated from human skin dermis. Human iPSC-SKPs differentiated into neural and mesodermal progenies, including adipocytes, skeletogenic cell types and Schwann cells. Moreover, they could be induced to follicular type keratinization when co-cultured with human epidermal keratinocytes. We here provide a new efficient protocol to create human skin dermal stem cells from hiPSCs that could contribute to the treatment of various skin disorders.

  10. Characterization of human neural differentiation from pluripotent stem cells using proteomics/PTMomics

    DEFF Research Database (Denmark)

    Braga, Marcella Nunes de Melo; Meyer, Morten; Zeng, Xianmin

    2015-01-01

    Stem cells are unspecialized cells capable of self-renewal and to differentiate into the large variety of cells in the body. The possibility to differentiate these cells into neural precursors and neural cells in vitro provides the opportunity to study neural development, nerve cell biology, neur...... differentiation from pluripotent stem cells. Moreover, some of the challenges in stem cell biology, differentiation, and proteomics/PTMomics that are not exclusive to neural development will be discussed.......Stem cells are unspecialized cells capable of self-renewal and to differentiate into the large variety of cells in the body. The possibility to differentiate these cells into neural precursors and neural cells in vitro provides the opportunity to study neural development, nerve cell biology...... the understanding of molecular processes in cells. Substantial advances in PTM enrichment methods and mass spectrometry has allowed the characterization of a subset of PTMs in large-scale studies. This review focuses on the current state-of-the-art of proteomic, as well as PTMomic studies related to human neural...

  11. Chaotic diagonal recurrent neural network

    International Nuclear Information System (INIS)

    Wang Xing-Yuan; Zhang Yi

    2012-01-01

    We propose a novel neural network based on a diagonal recurrent neural network and chaos, and its structure and learning algorithm are designed. The multilayer feedforward neural network, diagonal recurrent neural network, and chaotic diagonal recurrent neural network are used to approach the cubic symmetry map. The simulation results show that the approximation capability of the chaotic diagonal recurrent neural network is better than the other two neural networks. (interdisciplinary physics and related areas of science and technology)

  12. Understanding Animal Detection of Precursor Earthquake Sounds.

    Science.gov (United States)

    Garstang, Michael; Kelley, Michael C

    2017-08-31

    We use recent research to provide an explanation of how animals might detect earthquakes before they occur. While the intrinsic value of such warnings is immense, we show that the complexity of the process may result in inconsistent responses of animals to the possible precursor signal. Using the results of our research, we describe a logical but complex sequence of geophysical events triggered by precursor earthquake crustal movements that ultimately result in a sound signal detectable by animals. The sound heard by animals occurs only when metal or other surfaces (glass) respond to vibrations produced by electric currents induced by distortions of the earth's electric fields caused by the crustal movements. A combination of existing measurement systems combined with more careful monitoring of animal response could nevertheless be of value, particularly in remote locations.

  13. Metabolic Precursors to Amphetamine and Methamphetamine.

    Science.gov (United States)

    Cody, J D

    1993-12-01

    Analysis and interpretation of amphetamine results is a challenging process made difficult by a number of factors. One of the complications comes from determination of the origin of amphetamine or methamphetamine in a sample. Given the relatively rare occasions that either of these two drugs are prescribed, legal prescription of one of these drugs is seldom a reason for positive findings. A number of other precursor compounds are metabolized by the body to amphetamine or methamphetamine, many of which could be used for legitimate reasons. Fourteen different metabolic precursors of amphetamine or methamphetamine are included in this review. They are amphetaminil, benzphetamine, clobenzorex, deprenyl, dimethylamphetamine, ethylamphetamine, famprofazone, fencamine, fenethylline, fenproporex, furfenorex, mefenorex, mesocarb, and prenylamine. Medical use, metabolism, analysis, and interpretation are described to afford sufficient information to evaluate the possible involvement of these drugs in positive amphetamine or methamphetamine results. Copyright © 1993 Central Police University.

  14. Investigations on precursor measures for aeroelastic flutter

    Science.gov (United States)

    Venkatramani, J.; Sarkar, Sunetra; Gupta, Sayan

    2018-04-01

    Wind tunnel experiments carried out on a pitch-plunge aeroelastic system in the presence of fluctuating flows reveal that flutter instability is presaged by a regime of intermittency. It is observed that as the flow speed gradually increases towards the flutter speed, there appears intermittent bursts of periodic oscillations which become more frequent as the wind speed increases and eventually the dynamics transition into fully developed limit cycle oscillations, marking the onset of flutter. The signature from these intermittent oscillations are exploited to develop measures that forewarn a transition to flutter and can serve as precursors. This study investigates a suite of measures that are obtained directly from the time history of measurements and are hence model independent. The dependence of these precursors on the size of the measured data set and the time required for their computation is investigated. These measures can be useful in structural health monitoring of aeroelastic structures.

  15. Comparison exercise of probabilistic precursor analysis

    International Nuclear Information System (INIS)

    Fauchille, V.; Babst, S.

    2004-01-01

    From 2000 up to 2003, a comparison exercise concerning accident precursor programs was performed by IRSN, GRS, and NUPEC (Japan). The objective of this exercise was to compare the methodologies used to quantify conditional core damage probability related to incidents which can be considered as accident precursors. This exercise provided interesting results concerning the interpretation of such events. Generally, the participants identified similar scenarios of potential degradation. However, for several dominant sequences, differences in the results were noticed. The differences can be attributed to variations in the plant design, the strategy of management and in the methodological approach. For many reasons, comparison of human reliability analysis was difficult and perhaps another exercise in the future could provide more information about this subject. On the other hand, interesting outcomes have been obtained from the quantification of both common cause failures and potential common cause failures. (orig.)

  16. Functional Nanoporous Polymers from Block Copolymer Precursors

    DEFF Research Database (Denmark)

    Guo, Fengxiao

    Abstract Self-assembly of block copolymers provides well-defined morphologies with characteristic length scales in the nanometer range. Nanoporous polymers prepared by selective removal of one block from self-assembled block copolymers offer great technological promise due to their many potential...... functionalities remains a great challenge due to the limitation of available polymer synthesis and the nanoscale confinement of the porous cavities. The main topic of this thesis is to develop methods for fabrication of functional nanoporous polymers from block copolymer precursors. A method has been developed......, where living anionic polymerization and atom transfer radical polymerization (ATRP) are combined to synthesize a polydimethylsiloxane-b-poly(tert-butyl acrylate)-b-polystyrene (PDMS-b-PtBA-b-PS) triblock copolymer precursor. By using either anhydrous hydrogen fluoride or trifluoroacetic acid, PtBA block...

  17. Nonlinear magnetohydrodynamics of edge localized mode precursors

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Z. B., E-mail: guozhipku@gmail.com [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing (China); WCI Center for Fusion Theory, NFRI, Gwahangno 113, Yusung-gu, Daejeon 305-333 (Korea, Republic of); Wang, Lu [SEEE, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Wang, X. G. [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing (China)

    2015-02-15

    A possible origin of edge-localized-mode (ELM) precursors based on nonlinear ideal peeling-ballooning mode is reported. Via nonlinear variational principle, a nonlinear evolution equation of the radial displacement is derived and solved, analytically. Besides an explosive growth in the initial nonlinear phase, it is found that the local displacement evolves into an oscillating state in the developed nonlinear phase. The nonlinear frequency of the ELM precursors scales as ω{sub pre}∼x{sup 1/3}ξ{sup ^}{sub ψ,in}{sup 2/3}n, with x position in radial direction, ξ{sup ^}{sub ψ,in} strength of initial perturbation, and n toroidal mode number.

  18. Evolvable Neural Software System

    Science.gov (United States)

    Curtis, Steven A.

    2009-01-01

    The Evolvable Neural Software System (ENSS) is composed of sets of Neural Basis Functions (NBFs), which can be totally autonomously created and removed according to the changing needs and requirements of the software system. The resulting structure is both hierarchical and self-similar in that a given set of NBFs may have a ruler NBF, which in turn communicates with other sets of NBFs. These sets of NBFs may function as nodes to a ruler node, which are also NBF constructs. In this manner, the synthetic neural system can exhibit the complexity, three-dimensional connectivity, and adaptability of biological neural systems. An added advantage of ENSS over a natural neural system is its ability to modify its core genetic code in response to environmental changes as reflected in needs and requirements. The neural system is fully adaptive and evolvable and is trainable before release. It continues to rewire itself while on the job. The NBF is a unique, bilevel intelligence neural system composed of a higher-level heuristic neural system (HNS) and a lower-level, autonomic neural system (ANS). Taken together, the HNS and the ANS give each NBF the complete capabilities of a biological neural system to match sensory inputs to actions. Another feature of the NBF is the Evolvable Neural Interface (ENI), which links the HNS and ANS. The ENI solves the interface problem between these two systems by actively adapting and evolving from a primitive initial state (a Neural Thread) to a complicated, operational ENI and successfully adapting to a training sequence of sensory input. This simulates the adaptation of a biological neural system in a developmental phase. Within the greater multi-NBF and multi-node ENSS, self-similar ENI s provide the basis for inter-NBF and inter-node connectivity.

  19. Niche-dependent development of functional neuronal networks from embryonic stem cell-derived neural populations

    Directory of Open Access Journals (Sweden)

    Siebler Mario

    2009-08-01

    Full Text Available Abstract Background The present work was performed to investigate the ability of two different embryonic stem (ES cell-derived neural precursor populations to generate functional neuronal networks in vitro. The first ES cell-derived neural precursor population was cultivated as free-floating neural aggregates which are known to form a developmental niche comprising different types of neural cells, including neural precursor cells (NPCs, progenitor cells and even further matured cells. This niche provides by itself a variety of different growth factors and extracellular matrix proteins that influence the proliferation and differentiation of neural precursor and progenitor cells. The second population was cultivated adherently in monolayer cultures to control most stringently the extracellular environment. This population comprises highly homogeneous NPCs which are supposed to represent an attractive way to provide well-defined neuronal progeny. However, the ability of these different ES cell-derived immature neural cell populations to generate functional neuronal networks has not been assessed so far. Results While both precursor populations were shown to differentiate into sufficient quantities of mature NeuN+ neurons that also express GABA or vesicular-glutamate-transporter-2 (vGlut2, only aggregate-derived neuronal populations exhibited a synchronously oscillating network activity 2–4 weeks after initiating the differentiation as detected by the microelectrode array technology. Neurons derived from homogeneous NPCs within monolayer cultures did merely show uncorrelated spiking activity even when differentiated for up to 12 weeks. We demonstrated that these neurons exhibited sparsely ramified neurites and an embryonic vGlut2 distribution suggesting an inhibited terminal neuronal maturation. In comparison, neurons derived from heterogeneous populations within neural aggregates appeared as fully mature with a dense neurite network and punctuated

  20. PRECURSORS OF EARTHQUAKES: VLF SIGNALSIONOSPHERE IONOSPHERE RELATION

    Directory of Open Access Journals (Sweden)

    Mustafa ULAS

    2013-01-01

    Full Text Available lot of people have died because of earthquakes every year. Therefore It is crucial to predict the time of the earthquakes reasonable time before it had happed. This paper presents recent information published in the literature about precursors of earthquakes. The relationships between earthquakes and ionosphere are targeted to guide new researches in order to study further to find novel prediction methods.

  1. Lunar Robotic Precursor Missions Using Electric Propulsion

    OpenAIRE

    Winski, Richard G.

    2006-01-01

    A trade study is carried out for the design of electric propulsion based lunar robotic precursor missions. The focus is to understand the relationships between payload mass delivered, electric propulsion power, and trip time. The results are compared against a baseline system using chemical propulsion with LOX/H2. The major differences between the chemical propulsion based and electric propulsion based systems are presented in terms of the payload mass and trip time. It is shown that solar e...

  2. Ionospheric precursors for crustal earthquakes in Italy

    Directory of Open Access Journals (Sweden)

    L. Perrone

    2010-04-01

    Full Text Available Crustal earthquakes with magnitude 6.0>M≥5.5 observed in Italy for the period 1979–2009 including the last one at L'Aquila on 6 April 2009 were considered to check if the earlier obtained relationships for ionospheric precursors for strong Japanese earthquakes are valid for the Italian moderate earthquakes. The ionospheric precursors are based on the observed variations of the sporadic E-layer parameters (h'Es, fbEs and foF2 at the ionospheric station Rome. Empirical dependencies for the seismo-ionospheric disturbances relating the earthquake magnitude and the epicenter distance are obtained and they have been shown to be similar to those obtained earlier for Japanese earthquakes. The dependences indicate the process of spreading the disturbance from the epicenter towards periphery during the earthquake preparation process. Large lead times for the precursor occurrence (up to 34 days for M=5.8–5.9 tells about a prolong preparation period. A possibility of using the obtained relationships for the earthquakes prediction is discussed.

  3. Cellular Kinetics of Perivascular MSC Precursors

    Directory of Open Access Journals (Sweden)

    William C. W. Chen

    2013-01-01

    Full Text Available Mesenchymal stem/stromal cells (MSCs and MSC-like multipotent stem/progenitor cells have been widely investigated for regenerative medicine and deemed promising in clinical applications. In order to further improve MSC-based stem cell therapeutics, it is important to understand the cellular kinetics and functional roles of MSCs in the dynamic regenerative processes. However, due to the heterogeneous nature of typical MSC cultures, their native identity and anatomical localization in the body have remained unclear, making it difficult to decipher the existence of distinct cell subsets within the MSC entity. Recent studies have shown that several blood-vessel-derived precursor cell populations, purified by flow cytometry from multiple human organs, give rise to bona fide MSCs, suggesting that the vasculature serves as a systemic reservoir of MSC-like stem/progenitor cells. Using individually purified MSC-like precursor cell subsets, we and other researchers have been able to investigate the differential phenotypes and regenerative capacities of these contributing cellular constituents in the MSC pool. In this review, we will discuss the identification and characterization of perivascular MSC precursors, including pericytes and adventitial cells, and focus on their cellular kinetics: cell adhesion, migration, engraftment, homing, and intercellular cross-talk during tissue repair and regeneration.

  4. A neural flow estimator

    DEFF Research Database (Denmark)

    Jørgensen, Ivan Harald Holger; Bogason, Gudmundur; Bruun, Erik

    1995-01-01

    This paper proposes a new way to estimate the flow in a micromechanical flow channel. A neural network is used to estimate the delay of random temperature fluctuations induced in a fluid. The design and implementation of a hardware efficient neural flow estimator is described. The system...... is implemented using switched-current technique and is capable of estimating flow in the μl/s range. The neural estimator is built around a multiplierless neural network, containing 96 synaptic weights which are updated using the LMS1-algorithm. An experimental chip has been designed that operates at 5 V...

  5. Neural Systems Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — As part of the Electrical and Computer Engineering Department and The Institute for System Research, the Neural Systems Laboratory studies the functionality of the...

  6. Bioluminescence Imaging of Olig2-Neural Stem Cells Reveals Improved Engraftment in a Demyelination Mouse Model

    NARCIS (Netherlands)

    Sher, Falak; van Dam, Go; Boddeke, Erik; Copray, Sjef

    2009-01-01

    A major issue in the potential application of neural stem cell (NSC)-based cell replacement therapy for demyelinating diseases is the question of the survival, functional behavior, and stability of implanted NSC-derived oligodendrocyte precursor cells (OPCs) over an extended period. To address this

  7. Systemic Injection of Neural Stem/progenitor Cells in Mice With Chronic EAE

    OpenAIRE

    Donegà, Matteo; Giusto, Elena; Cossetti, Chiara; Schaeffer, Julia; Pluchino, Stefano

    2014-01-01

    Neural stem/precursor cells (NPCs) are a promising stem cell source for transplantation approaches aiming at brain repair or restoration in regenerative neurology. This directive has arisen from the extensive evidence that brain repair is achieved after focal or systemic NPC transplantation in several pre clinical models of neurological diseases.

  8. Neural Networks: Implementations and Applications

    OpenAIRE

    Vonk, E.; Veelenturf, L.P.J.; Jain, L.C.

    1996-01-01

    Artificial neural networks, also called neural networks, have been used successfully in many fields including engineering, science and business. This paper presents the implementation of several neural network simulators and their applications in character recognition and other engineering areas

  9. Meat flavor precursors and factors influencing flavor precursors--A systematic review.

    Science.gov (United States)

    Khan, Muhammad Issa; Jo, Cheorun; Tariq, Muhammad Rizwan

    2015-12-01

    Flavor is the sensory impression sensed by taste and smell buds and is a leading factor determining the meat quality and purchasing decision of the consumer. Meat flavor is characteristic of volatiles produced as a result of reactions of non-volatile components that are induced thermally. The water soluble compounds having low molecular weight and meat lipids are important precursors of cooked meat flavor. The Maillard reaction, lipid oxidation, and vitamin degradation are leading reactions during cooking which develop meat flavor from uncooked meat with little aroma and bloody taste. The pre-slaughter and postmortem factors like animal breed, sex, age, feed, aging and cooking conditions contribute to flavor development of cooked meat. The objective of this review is to highlight the flavor chemistry, meat flavor precursors and factors affecting meat flavor precursors. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Non radioactive precursor import into chloroplasts

    International Nuclear Information System (INIS)

    Lombardo, V.A.; Ottado, J.

    2003-01-01

    Full text: Eukaryotic cells have a subcellular organization based on organelles. Protein transport to these organelles is quantitatively important because the majority of cellular proteins are codified in nuclear genes and then delivered to their final destination. Most of the chloroplast proteins are translated on cytoplasmic ribosomes as larger precursors with an amino terminal transit peptide that is necessary and sufficient to direct the precursor to the chloroplast. Once inside the organelle the transit peptide is cleaved and the mature protein adopts its folded form. In this work we developed a system for the expression and purification of the pea ferredoxin-NADP + reductase precursor (preFNR) for its import into chloroplasts in non radioactive conditions. We constructed a preFNR fused in its carboxy terminus to a 6 histidines peptide (preFNR-6xHis) that allows its identification using a commercial specific antibody. The construction was expressed, purified, processed and precipitated, rendering a soluble and active preFNR-6xHis that was used in binding and import into chloroplasts experiments. The reisolated chloroplasts were analyzed by SDS-PAGE, electro-blotting and revealed by immuno-detection using either colorimetric or chemiluminescent reactive. We performed also import experiments labeling preFNR and preFNR-6xHis with radioactive methionine as controls. We conclude that preFNR-6xHis is bound and imported into chloroplasts as the wild type preFNR and that both colorimetric or chemiluminescent detection methods are useful to avoid the manipulation of radioactive material. (author)

  11. NOx emissions trading: Precursor to future growth

    International Nuclear Information System (INIS)

    Colella, A.

    1993-01-01

    Title I of the Clean Air Act Amendments (CAAA) of 1990 specified the framework for enhanced regulation in ozone non-attainment areas with increasingly stringent requirements dependent on the area classification - marginal, moderate, serious, severe or extreme. Before the CAAA were passed, only volatile organic compounds (VOCs) were regulated as precursors to ozone formation, Now, by statute, emissions of nitrogen oxides (NO x ) are also regulated as ozone precursor. Under the CAAA, new sources and modifications of existing sources are subject to Title I permitting requirements in ozone non-attainment areas if emissions of NO x and/or VOCs exceed certain triggering levels. For many new or facility expansion projects, especially power generation, the NO x thresholds are easily exceeded thus triggering Title I non-attainment new source review which requires application of control technology to new equipment which results in the Lowest Achievable Emission Rate (LAER), and securing emission reductions either internally or from other major sources to offset the increased emission from the new or modified source. The selection of a LAER technology is generally within an applicant's control. An applicant can determine up-front the engineering and cost considerations associated with LAER technology is assessing a project's viability. However, without a clear source of emission offsets of a means to secure them, assessing project viability could be difficult if not impossible. No available emission offsets means no industrial growth. For sources of NO x undergoing Title I new source review, a regional or state banking system that facilitates NO x emissions trading is needed as a precursor to future growth. This paper presents an overview of EPA's Emissions Trading Policy and Title I new source review offset provisions. Industry's concerns about emissions trading and recommendations for future trading programs are presented

  12. Amorphous Alloy: Promising Precursor to Form Nanoflowerpot

    Directory of Open Access Journals (Sweden)

    Guo Lan

    2014-01-01

    Full Text Available Nanoporous copper is fabricated by dealloying the amorphous Ti2Cu alloy in 0.03 M HF electrolyte. The pore and ligament sizes of the nanoporous copper can be readily tailored by controlling the dealloying time. The as-prepared nanoporous copper provides fine and uniform nanoflowerpots to grow highly dispersed Au nanoflowers. The blooming Au nanoflowers in the nanoporous copper flowerpots exhibit both high catalytic activity and stability towards the oxidation of glucose, indicating that the amorphous alloys are ideal precursors to form nanoflowerpot which can grow functional nanoflowers.

  13. Iron filled carbon nanostructures from different precursors

    International Nuclear Information System (INIS)

    Costa, S.; Borowiak-Palen, E.; Bachmatiuk, A.; Ruemmeli, M.H.; Gemming, T.; Kalenczuk, R.J.

    2008-01-01

    Here, we present a study on the synthesis of different nanostructures with one single-step in situ filling (encapsulation) via carbon vapor deposition (CVD). Ferrocene, acetylferrocene and iron (II) nitrate as iron precursors were explored. The application of each of these compounds resulted in different carbon nanomaterials such as: iron filled multiwalled carbon nanotubes with a low filling ratio (Fe-MWCNT), iron filled nanocapsules and unfilled MWCNT. The as-produced samples were purified by high temperature annealing and acid treatment. The purified materials were characterised using transmission electron microscopy (TEM) and Raman spectroscopy

  14. Critical Branching Neural Networks

    Science.gov (United States)

    Kello, Christopher T.

    2013-01-01

    It is now well-established that intrinsic variations in human neural and behavioral activity tend to exhibit scaling laws in their fluctuations and distributions. The meaning of these scaling laws is an ongoing matter of debate between isolable causes versus pervasive causes. A spiking neural network model is presented that self-tunes to critical…

  15. Consciousness and neural plasticity

    DEFF Research Database (Denmark)

    changes or to abandon the strong identity thesis altogether. Were one to pursue a theory according to which consciousness is not an epiphenomenon to brain processes, consciousness may in fact affect its own neural basis. The neural correlate of consciousness is often seen as a stable structure, that is...

  16. Fluorinated Phenylalanine Precursor Resistance in Yeast

    Directory of Open Access Journals (Sweden)

    Ian S. Murdoch

    2018-06-01

    Full Text Available Development of a counter-selection method for phenylalanine auxotrophy could be a useful tool in the repertoire of yeast genetics. Fluorinated and sulfurated precursors of phenylalanine were tested for toxicity in Saccharomyces cerevisiae. One such precursor, 4-fluorophenylpyruvate (FPP, was found to be toxic to several strains from the Saccharomyces and Candida genera. Toxicity was partially dependent on ARO8 and ARO9, and correlated with a strain’s ability to convert FPP into 4-fluorophenylalanine (FPA. Thus, strains with deletions in ARO8 and ARO9, having a mild phenylalanine auxotrophy, could be separated from a culture of wild-type strains using FPP. Tetrad analysis suggests FPP resistance in one strain is due to two genes. Strains resistant to FPA have previously been shown to exhibit increased phenylethanol production. However, FPP resistant isolates did not follow this trend. These results suggest that FPP could effectively be used for counter-selection but not for enhanced phenylethanol production.

  17. Precursor Mediated Synthesis of Nanostructured Silicas: From Precursor-Surfactant Ion Pairs to Structured Materials.

    Science.gov (United States)

    Hesemann, Peter; Nguyen, Thy Phung; Hankari, Samir El

    2014-04-11

    The synthesis of nanostructured anionic-surfactant-templated mesoporous silica (AMS) recently appeared as a new strategy for the formation of nanostructured silica based materials. This method is based on the use of anionic surfactants together with a co-structure-directing agent (CSDA), mostly a silylated ammonium precursor. The presence of this CSDA is necessary in order to create ionic interactions between template and silica forming phases and to ensure sufficient affinity between the two phases. This synthetic strategy was for the first time applied in view of the synthesis of surface functionalized silica bearing ammonium groups and was then extended on the formation of materials functionalized with anionic carboxylate and bifunctional amine-carboxylate groups. In the field of silica hybrid materials, the "anionic templating" strategy has recently been applied for the synthesis of silica hybrid materials from cationic precursors. Starting from di- or oligosilylated imidazolium and ammonium precursors, only template directed hydrolysis-polycondensation reactions involving complementary anionic surfactants allowed accessing structured ionosilica hybrid materials. The mechanistic particularity of this approach resides in the formation of precursor-surfactant ion pairs in the hydrolysis-polycondensation mixture. This review gives a systematic overview over the various types of materials accessed from this cooperative ionic templating approach and highlights the high potential of this original strategy for the formation of nanostructured silica based materials which appears as a complementary strategy to conventional soft templating approaches.

  18. Precursor Mediated Synthesis of Nanostructured Silicas: From Precursor-Surfactant Ion Pairs to Structured Materials

    Directory of Open Access Journals (Sweden)

    Peter Hesemann

    2014-04-01

    Full Text Available The synthesis of nanostructured anionic-surfactant-templated mesoporous silica (AMS recently appeared as a new strategy for the formation of nanostructured silica based materials. This method is based on the use of anionic surfactants together with a co-structure-directing agent (CSDA, mostly a silylated ammonium precursor. The presence of this CSDA is necessary in order to create ionic interactions between template and silica forming phases and to ensure sufficient affinity between the two phases. This synthetic strategy was for the first time applied in view of the synthesis of surface functionalized silica bearing ammonium groups and was then extended on the formation of materials functionalized with anionic carboxylate and bifunctional amine-carboxylate groups. In the field of silica hybrid materials, the “anionic templating” strategy has recently been applied for the synthesis of silica hybrid materials from cationic precursors. Starting from di- or oligosilylated imidazolium and ammonium precursors, only template directed hydrolysis-polycondensation reactions involving complementary anionic surfactants allowed accessing structured ionosilica hybrid materials. The mechanistic particularity of this approach resides in the formation of precursor-surfactant ion pairs in the hydrolysis-polycondensation mixture. This review gives a systematic overview over the various types of materials accessed from this cooperative ionic templating approach and highlights the high potential of this original strategy for the formation of nanostructured silica based materials which appears as a complementary strategy to conventional soft templating approaches.

  19. Plasticity of Calcium Signaling Cascades in Human Embryonic Stem Cell-Derived Neural Precursors

    Czech Academy of Sciences Publication Activity Database

    Forostyak, Oksana; Romanyuk, Nataliya; Verkhratsky, A.; Syková, Eva; Dayanithi, Govindan

    2013-01-01

    Roč. 22, č. 10 (2013), s. 1506-1521 ISSN 1547-3287 R&D Projects: GA ČR GAP304/11/2373; GA ČR(CZ) GBP304/12/G069 Grant - others:FP7(XE) PITN-GA-2008-214003 project AXREGEN; FP7(XE) PITN-GA-2009-237956 project EdU-GLIA Institutional support: RVO:68378041 Keywords : human embryonic stem cells * voltage-operated Ca2+ channels * spontaneous Ca2+ oscillations Subject RIV: FH - Neurology Impact factor: 4.202, year: 2013

  20. Physiology of CA2+ signaling in human embryonic stem cell-derived neural precursors

    Czech Academy of Sciences Publication Activity Database

    Forostyak, Oksana; Romanyuk, Nataliya; Syková, Eva; Dayanithi, Govindan

    2011-01-01

    Roč. 59, S1 (2011), S119-S119 ISSN 0894-1491. [European meeting on Glia l Cells in Health and Disease /10./. 13.09.2011-17.09.2011, Prague] R&D Projects: GA ČR(CZ) GAP303/11/0192 Institutional research plan: CEZ:AV0Z50390703 Keywords : calcium signaling * ATP * calcium channels Subject RIV: FH - Neurology

  1. Mobilization of Neural Precursors in the Circulating Blood of Patients with Multiple Sclerosis

    Science.gov (United States)

    2013-09-01

    Bongarzone ER. Expression of sonic hedgehog targeted genes in peripheral blood mononuclear cells of patients with multiple sclerosis. Society for...recovery in a rat spinal cord injury model. Spine (Phila Pa 1976) 34:249-254. Schwartz PH, Bryant PJ, Fuja TJ, Su H, O’Dowd DK, Klassen H (2003...Print Program#/Poster#: 322.13 Presentation Title: Expression of sonic  hedgehog  targeted genes in peripheral blood mononuclear cells of patients with

  2. Dynamics of neural cryptography.

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-05-01

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.

  3. Dynamics of neural cryptography

    International Nuclear Information System (INIS)

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-01-01

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible

  4. Dynamics of neural cryptography

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-05-01

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.

  5. ANT Advanced Neural Tool

    Energy Technology Data Exchange (ETDEWEB)

    Labrador, I.; Carrasco, R.; Martinez, L.

    1996-07-01

    This paper describes a practical introduction to the use of Artificial Neural Networks. Artificial Neural Nets are often used as an alternative to the traditional symbolic manipulation and first order logic used in Artificial Intelligence, due the high degree of difficulty to solve problems that can not be handled by programmers using algorithmic strategies. As a particular case of Neural Net a Multilayer Perception developed by programming in C language on OS9 real time operating system is presented. A detailed description about the program structure and practical use are included. Finally, several application examples that have been treated with the tool are presented, and some suggestions about hardware implementations. (Author) 15 refs.

  6. ANT Advanced Neural Tool

    International Nuclear Information System (INIS)

    Labrador, I.; Carrasco, R.; Martinez, L.

    1996-01-01

    This paper describes a practical introduction to the use of Artificial Neural Networks. Artificial Neural Nets are often used as an alternative to the traditional symbolic manipulation and first order logic used in Artificial Intelligence, due the high degree of difficulty to solve problems that can not be handled by programmers using algorithmic strategies. As a particular case of Neural Net a Multilayer Perception developed by programming in C language on OS9 real time operating system is presented. A detailed description about the program structure and practical use are included. Finally, several application examples that have been treated with the tool are presented, and some suggestions about hardware implementations. (Author) 15 refs

  7. Lessons learned on probabilistic methodology for precursor analyses

    International Nuclear Information System (INIS)

    Babst, Siegfried; Wielenberg, Andreas; Gaenssmantel, Gerhard

    2016-01-01

    Based on its experience in precursor assessment of operating experience from German NPP and related international activities in the field, GRS has identified areas for enhancing probabilistic methodology. These are related to improving the completeness of PSA models, to insufficiencies in probabilistic assessment approaches, and to enhancements of precursor assessment methods. Three examples from the recent practice in precursor assessments illustrating relevant methodological insights are provided and discussed in more detail. Our experience reinforces the importance of having full scope, current PSA models up to Level 2 PSA and including hazard scenarios for precursor analysis. Our lessons learned include that PSA models should be regularly updated regarding CCF data and inclusion of newly discovered CCF mechanisms or groups. Moreover, precursor classification schemes should be extended to degradations and unavailabilities of the containment function. Finally, PSA and precursor assessments should put more emphasis on the consideration of passive provisions for safety, e. g. by sensitivity cases.

  8. Lessons learned on probabilistic methodology for precursor analyses

    Energy Technology Data Exchange (ETDEWEB)

    Babst, Siegfried [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) gGmbH, Berlin (Germany); Wielenberg, Andreas; Gaenssmantel, Gerhard [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) gGmbH, Garching (Germany)

    2016-11-15

    Based on its experience in precursor assessment of operating experience from German NPP and related international activities in the field, GRS has identified areas for enhancing probabilistic methodology. These are related to improving the completeness of PSA models, to insufficiencies in probabilistic assessment approaches, and to enhancements of precursor assessment methods. Three examples from the recent practice in precursor assessments illustrating relevant methodological insights are provided and discussed in more detail. Our experience reinforces the importance of having full scope, current PSA models up to Level 2 PSA and including hazard scenarios for precursor analysis. Our lessons learned include that PSA models should be regularly updated regarding CCF data and inclusion of newly discovered CCF mechanisms or groups. Moreover, precursor classification schemes should be extended to degradations and unavailabilities of the containment function. Finally, PSA and precursor assessments should put more emphasis on the consideration of passive provisions for safety, e. g. by sensitivity cases.

  9. Mars MetNet Precursor Mission Status

    Science.gov (United States)

    Harri, A.-M.; Aleksashkin, S.; Guerrero, H.; Schmidt, W.; Genzer, M.; Vazquez, L.; Haukka, H.

    2013-09-01

    We are developing a new kind of planetary exploration mission for Mars in collaboration between the Finnish Meteorological Institute (FMI), Lavochkin Association (LA), Space Research Institute (IKI) and Institutio Nacional de Tecnica Aerospacial (INTA). The Mars MetNet mission is based on a new semi-hard landing vehicle called MetNet Lander (MNL). The scientific payload of the Mars MetNet Precursor [1] mission is divided into three categories: Atmospheric instruments, Optical devices and Composition and structure devices. Each of the payload instruments will provide significant insights in to the Martian atmospheric behavior. The key technologies of the MetNet Lander have been qualified and the electrical qualification model (EQM) of the payload bay has been built and successfully tested.

  10. Precursors to suicidality and violence on antidepressants

    DEFF Research Database (Denmark)

    Bielefeldt, Andreas Ø; Danborg, Pia B; Gøtzsche, Peter C

    2016-01-01

    OBJECTIVE: To quantify the risk of suicidality and violence when selective serotonin and serotonin-norepinephrine reuptake inhibitors are given to adult healthy volunteers with no signs of a mental disorder. DESIGN: Systematic review and meta-analysis. MAIN OUTCOME MEASURE: Harms related...... to suicidality, hostility, activation events, psychotic events and mood disturbances. SETTING: Published trials identified by searching PubMed and Embase and clinical study reports obtained from the European and UK drug regulators. PARTICIPANTS: Double-blind, placebo-controlled trials in adult healthy volunteers...... that reported on suicidality or violence or precursor events to suicidality or violence. RESULTS: A total of 5787 publications were screened and 130 trials fulfilled our inclusion criteria. The trials were generally uninformative; 97 trials did not report the randomisation method, 75 trials did not report any...

  11. German precursor study: methods and results

    International Nuclear Information System (INIS)

    Hoertner, H.; Frey, W.; von Linden, J.; Reichart, G.

    1985-01-01

    This study has been prepared by the GRS by contract of the Federal Minister of Interior. The purpose of the study is to show how the application of system-analytic tools and especially of probabilistic methods on the Licensee Event Reports (LERs) and on other operating experience can support a deeper understanding of the safety-related importance of the events reported in reactor operation, the identification of possible weak points, and further conclusions to be drawn from the events. Additionally, the study aimed at a comparison of its results for the severe core damage frequency with those of the German Risk Study as far as this is possible and useful. The German Precursor Study is a plant-specific study. The reference plant is Biblis NPP with its very similar Units A and B, whereby the latter was also the reference plant for the German Risk Study

  12. Silicon dioxide obtained by Polymeric Precursor Method

    International Nuclear Information System (INIS)

    Oliveira, C.T.; Granado, S.R.; Lopes, S.A.; Cavalheiro, A.A.

    2011-01-01

    The Polymeric Precursor Method is able for obtaining several oxide material types with high surface area even obtained in particle form. Several MO 2 oxide types such as titanium, silicon and zirconium ones can be obtained by this methodology. In this work, the synthesis of silicon oxide was monitored by thermal analysis, XRD and surface area analysis in order to demonstrate the influence of the several synthesis and calcining parameters. Surface area values as higher as 370m2/g and increasing in the micropore volume nm were obtained when the material was synthesized by using ethylene glycol as polymerizing agent. XRD analysis showed that the material is amorphous when calcinated at 600°C in despite of the time of calcining, but the material morphology is strongly influenced by the polymeric resin composition. Using Glycerol as polymerizing agent, the pore size increase and the surface area goes down with the increasing in decomposition time, when compared to ethylene glycol. (author)

  13. Ancient engineers' inventions precursors of the present

    CERN Document Server

    Rossi, Cesare

    2017-01-01

    This book describes the inventions and designs of ancient engineers who are the precursors of the present. The period ranges mainly from 300 B.C. to 1600 A.D. with several exceptions. Many of the oldest inventions are documented by archaeological finds, often very little known, mainly from Pompeii, Herculaneum and Stabiae and reveal a surprising modernity in their conception. Most of the inventions presented in the first four parts of the book were conceived up to the late Roman Empire and may be considered as milestones, each in their respective field. The fifth part concentrates on more recent centuries. The sixth part deals with some building construction techniques. Generally, for each of the presented inventions, three elements of research and reference are provided: written documents (the classics), iconic references (coins, bas-reliefs, etc.) and archaeological findings. The authors did not write this book for engineers only; hence they describe all the devices without assuming wide technical knowledge...

  14. Precursor conditions related to Zimbabwe's summer droughts

    Science.gov (United States)

    Nangombe, Shingirai; Madyiwa, Simon; Wang, Jianhong

    2018-01-01

    Despite the increasing severity of droughts and their effects on Zimbabwe's agriculture, there are few tools available for predicting these droughts in advance. Consequently, communities and farmers are more exposed, and policy makers are always ill prepared for such. This study sought to investigate possible cycles and precursor meteorological conditions prior to drought seasons that could be used to predict impending droughts in Zimbabwe. The Single Z-Index was used to identify and grade drought years between 1951 and 2010 according to rainfall severity. Spectral analysis was used to reveal the cycles of droughts for possible use of these cycles for drought prediction. Composite analysis was used to investigate circulation and temperature anomalies associated with severe and extreme drought years. Results indicate that severe droughts are more highly correlated with circulation patterns and embedded weather systems in the Indian Ocean and equatorial Pacific Ocean than any other area. This study identified sea surface temperatures in the average period June to August, geopotential height and wind vector in July to September period, and air temperature in September to November period as precursors that can be used to predict a drought occurrence several months in advance. Therefore, in addition to sea surface temperature, which was identified through previous research for predicting Zimbabwean droughts, the other parameters identified in this study can aid in drought prediction. Drought cycles were established at 20-, 12.5-, 3.2-, and 2.7-year cycles. The spectral peaks, 12.5, 3.2, and 2.7, had a similar timescale with the luni-solar tide, El Niño Southern Oscillation and Quasi Biennial Oscillation, respectively, and hence, occurrence of these phenomena have a possibility of indicating when the next drought might be.

  15. Hidden neural networks

    DEFF Research Database (Denmark)

    Krogh, Anders Stærmose; Riis, Søren Kamaric

    1999-01-01

    A general framework for hybrids of hidden Markov models (HMMs) and neural networks (NNs) called hidden neural networks (HNNs) is described. The article begins by reviewing standard HMMs and estimation by conditional maximum likelihood, which is used by the HNN. In the HNN, the usual HMM probability...... parameters are replaced by the outputs of state-specific neural networks. As opposed to many other hybrids, the HNN is normalized globally and therefore has a valid probabilistic interpretation. All parameters in the HNN are estimated simultaneously according to the discriminative conditional maximum...... likelihood criterion. The HNN can be viewed as an undirected probabilistic independence network (a graphical model), where the neural networks provide a compact representation of the clique functions. An evaluation of the HNN on the task of recognizing broad phoneme classes in the TIMIT database shows clear...

  16. Thin HTSC films produced by a polymer metal precursor technique

    Science.gov (United States)

    Lampe, L. v.; Zygalsky, F.; Hinrichsen, G.

    In precursors the metal ions are combined with acid groups of polymethacrylic acid (PMAA), polyacrylic acid (PAA) or novolac. Compared to thermal degradation temperature of pure polymers those of precursors are low. Precursors films were patterned by UV lithography. Diffractometric investigations showed that the c-axis oriented epitaxial films of YBa 2Cu 3O x and Bi 2Sr 2CaCu 2O x originated from amorphous metal oxide films, which were received after thermal degradation of the precursor. Transition temperatures and current densities were determined by electric resistivity measurements.

  17. Neural networks for aircraft control

    Science.gov (United States)

    Linse, Dennis

    1990-01-01

    Current research in Artificial Neural Networks indicates that networks offer some potential advantages in adaptation and fault tolerance. This research is directed at determining the possible applicability of neural networks to aircraft control. The first application will be to aircraft trim. Neural network node characteristics, network topology and operation, neural network learning and example histories using neighboring optimal control with a neural net are discussed.

  18. Active Neural Localization

    OpenAIRE

    Chaplot, Devendra Singh; Parisotto, Emilio; Salakhutdinov, Ruslan

    2018-01-01

    Localization is the problem of estimating the location of an autonomous agent from an observation and a map of the environment. Traditional methods of localization, which filter the belief based on the observations, are sub-optimal in the number of steps required, as they do not decide the actions taken by the agent. We propose "Active Neural Localizer", a fully differentiable neural network that learns to localize accurately and efficiently. The proposed model incorporates ideas of tradition...

  19. Neural cryptography with feedback.

    Science.gov (United States)

    Ruttor, Andreas; Kinzel, Wolfgang; Shacham, Lanir; Kanter, Ido

    2004-04-01

    Neural cryptography is based on a competition between attractive and repulsive stochastic forces. A feedback mechanism is added to neural cryptography which increases the repulsive forces. Using numerical simulations and an analytic approach, the probability of a successful attack is calculated for different model parameters. Scaling laws are derived which show that feedback improves the security of the system. In addition, a network with feedback generates a pseudorandom bit sequence which can be used to encrypt and decrypt a secret message.

  20. Prolonged Expansion Induces Spontaneous Neural Progenitor Differentiation from Human Gingiva-Derived Mesenchymal Stem Cells.

    Science.gov (United States)

    Rajan, Thangavelu Soundara; Scionti, Domenico; Diomede, Francesca; Piattelli, Adriano; Bramanti, Placido; Mazzon, Emanuela; Trubiani, Oriana

    2017-12-01

    Neural crest-derived mesenchymal stem cells (MSCs) obtained from dental tissues received considerable interest in regenerative medicine, particularly in nerve regeneration owing to their embryonic origin and ease of harvest. Proliferation efficacy and differentiation capacity into diverse cell lineages propose dental MSCs as an in vitro tool for disease modeling. In this study, we investigated the spontaneous differentiation efficiency of dental MSCs obtained from human gingiva tissue (hGMSCs) into neural progenitor cells after extended passaging. At passage 41, the morphology of hGMSCs changed from typical fibroblast-like shape into sphere-shaped cells with extending processes. Next-generation transcriptomics sequencing showed increased expression of neural progenitor markers such as NES, MEIS2, and MEST. In addition, de novo expression of neural precursor genes, such as NRN1, PHOX2B, VANGL2, and NTRK3, was noticed in passage 41. Immunocytochemistry results showed suppression of neurogenesis repressors TP53 and p21, whereas Western blot results revealed the expression of neurotrophic factors BDNF and NT3 at passage 41. Our results showed the spontaneous efficacy of hGMSCs to differentiate into neural precursor cells over prolonged passages and that these cells may assist in producing novel in vitro disease models that are associated with neural development.

  1. Regeneration of neural crest derivatives in the Xenopus tadpole tail

    Directory of Open Access Journals (Sweden)

    Slack Jonathan MW

    2007-05-01

    Full Text Available Abstract Background After amputation of the Xenopus tadpole tail, a functionally competent new tail is regenerated. It contains spinal cord, notochord and muscle, each of which has previously been shown to derive from the corresponding tissue in the stump. The regeneration of the neural crest derivatives has not previously been examined and is described in this paper. Results Labelling of the spinal cord by electroporation, or by orthotopic grafting of transgenic tissue expressing GFP, shows that no cells emigrate from the spinal cord in the course of regeneration. There is very limited regeneration of the spinal ganglia, but new neurons as well as fibre tracts do appear in the regenerated spinal cord and the regenerated tail also contains abundant peripheral innervation. The regenerated tail contains a normal density of melanophores. Cell labelling experiments show that melanophores do not arise from the spinal cord during regeneration, nor from the mesenchymal tissues of the skin, but they do arise by activation and proliferation of pre-existing melanophore precursors. If tails are prepared lacking melanophores, then the regenerates also lack them. Conclusion On regeneration there is no induction of a new neural crest similar to that seen in embryonic development. However there is some regeneration of neural crest derivatives. Abundant melanophores are regenerated from unpigmented precursors, and, although spinal ganglia are not regenerated, sufficient sensory systems are produced to enable essential functions to continue.

  2. Development of an accident sequence precursor methodology and its application to significant accident precursors

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Seung Hyun; Park, Sung Hyun; Jae, Moo Sung [Dept. of of Nuclear Engineering, Hanyang University, Seoul (Korea, Republic of)

    2017-03-15

    The systematic management of plant risk is crucial for enhancing the safety of nuclear power plants and for designing new nuclear power plants. Accident sequence precursor (ASP) analysis may be able to provide risk significance of operational experience by using probabilistic risk assessment to evaluate an operational event quantitatively in terms of its impact on core damage. In this study, an ASP methodology for two operation mode, full power and low power/shutdown operation, has been developed and applied to significant accident precursors that may occur during the operation of nuclear power plants. Two operational events, loss of feedwater and steam generator tube rupture, are identified as ASPs. Therefore, the ASP methodology developed in this study may contribute to identifying plant risk significance as well as to enhancing the safety of nuclear power plants by applying this methodology systematically.

  3. Precursors of chicken flavor. II. Identification of key flavor precursors using sensory methods.

    Science.gov (United States)

    Aliani, Michel; Farmer, Linda J

    2005-08-10

    Sensory evaluation was used to identify flavor precursors that are critical for flavor development in cooked chicken. Among the potential flavor precursors studied (thiamin, inosine 5'-monophosphate, ribose, ribose-5-phosphate, glucose, and glucose-6-phosphate), ribose appears most important for chicken aroma. An elevated concentration (added or natural) of only 2-4-fold the natural concentration gives an increase in the selected aroma and flavor attributes of cooked chicken meat. Assessment of the volatile odor compounds by gas chromatography-odor assessment and gas chromatography-mass spectrometry showed that ribose increased odors described as "roasted" and "chicken" and that the changes in odor due to additional ribose are probably caused by elevated concentrations of compounds such as 2-furanmethanethiol, 2-methyl-3-furanthiol, and 3-methylthiopropanal.

  4. Astrocytes from the Contused Spinal Cord Inhibit Oligodendrocyte Differentiation of Adult Oligodendrocyte Precursor Cells by Increasing the Expression of Bone Morphogenetic Proteins

    OpenAIRE

    Wang, Yaping; Cheng, Xiaoxin; He, Qian; Zheng, Yiyan; Kim, Dong H.; Whittemore, Scott R.; Cao, Qilin L.

    2011-01-01

    Promotion of remyelination is an important therapeutic strategy to facilitate functional recovery after traumatic spinal cord injury (SCI). Transplantation of neural stem cells (NSCs) or oligodendrocyte precursor cells (OPCs) has been used to enhance remyelination after SCI. However, the microenvironment in the injured spinal cord is inhibitory for oligodendrocyte (OL) differentiation of NSCs or OPCs. Identifying the signaling pathways that inhibit OL differentiation in the injured spinal cor...

  5. Enumeration of minimal stoichiometric precursor sets in metabolic networks.

    Science.gov (United States)

    Andrade, Ricardo; Wannagat, Martin; Klein, Cecilia C; Acuña, Vicente; Marchetti-Spaccamela, Alberto; Milreu, Paulo V; Stougie, Leen; Sagot, Marie-France

    2016-01-01

    What an organism needs at least from its environment to produce a set of metabolites, e.g. target(s) of interest and/or biomass, has been called a minimal precursor set. Early approaches to enumerate all minimal precursor sets took into account only the topology of the metabolic network (topological precursor sets). Due to cycles and the stoichiometric values of the reactions, it is often not possible to produce the target(s) from a topological precursor set in the sense that there is no feasible flux. Although considering the stoichiometry makes the problem harder, it enables to obtain biologically reasonable precursor sets that we call stoichiometric. Recently a method to enumerate all minimal stoichiometric precursor sets was proposed in the literature. The relationship between topological and stoichiometric precursor sets had however not yet been studied. Such relationship between topological and stoichiometric precursor sets is highlighted. We also present two algorithms that enumerate all minimal stoichiometric precursor sets. The first one is of theoretical interest only and is based on the above mentioned relationship. The second approach solves a series of mixed integer linear programming problems. We compared the computed minimal precursor sets to experimentally obtained growth media of several Escherichia coli strains using genome-scale metabolic networks. The results show that the second approach efficiently enumerates minimal precursor sets taking stoichiometry into account, and allows for broad in silico studies of strains or species interactions that may help to understand e.g. pathotype and niche-specific metabolic capabilities. sasita is written in Java, uses cplex as LP solver and can be downloaded together with all networks and input files used in this paper at http://www.sasita.gforge.inria.fr.

  6. Isolation of skin-derived precursors from human foreskin and their differentiation into neurons and glial cells

    Directory of Open Access Journals (Sweden)

    Bakhtiari M

    2010-12-01

    Full Text Available "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: Skin-derived precursors (SKPs are a type of progenitor cells extracted from mammalian dermal tissue and can be differentiate to neural and mesodermal lineage in vitro. These cells can introduce an accessible autologos source of neural precursor cells for treatment of different neurodegenerative diseases. This research was done in order to set up isolation, culture, proliferation and differentiation of human skin derived precursors (hSKPs."n"nMethods: Human foreskin samples were cut into smaller pieces and cultured in proliferation medium after enzymatic digestion. To induce neural differentiation, cells were cultured in neural differentiation medium after fifth passage. We used immunocytochemistry and RT-PCR for characterization of the cells. Neuron and glial cell differentiation potential was assessed by immunofloresence using specific antibodies. The experiments were carried out in triplicate."n"nResults: After differentiation, βΙΙΙ- tubulin and neurofilament-M positive cells were observed that are specific markers for neurons. Moreover, glial fibrillary acid protein (GFAP and S100 positive cells were identified that are markers specifically express in glial cells. Detected neurons and glials were

  7. Hydrodeoxygenation of coal using organometallic catalyst precursors

    Science.gov (United States)

    Kirby, Stephen R.

    2002-04-01

    coals. Trends within the data were similar to those reported by other authors. Based on the conclusions from both the model compound studies and the coal analysis, predictions were made of the catalyst precursors' performance in the HDO of the three selected coals. It was concluded that CoMo-T2 is a desirable catalyst precursor for the HDO of coals (particularly low-rank coals), but that an optimum set of conditions must be determined to take full advantage of its HDO ability. (Abstract shortened by UMI.)

  8. Operational experience feedback with precursor analysis

    International Nuclear Information System (INIS)

    Koncar, M.; Ferjancic, M.; Muehleisen, A.; Vojnovic, D.

    2003-01-01

    Experience of practical operation is a valuable source of information for improving the safety and reliability of nuclear power plants. Operational experience feedback (Olef) system manages this aspect of NPP operation. The traditional ways of investigating operational events, such as the root cause analysis (RCA), are predominantly qualitative. RCA as a part of the Olef system provides technical guidance and management expectations in the conduct of assessing the root cause to prevent recurrence, covering the following areas: conditions preceding the event, sequence of events, equipment performance and system response, human performance considerations, equipment failures, precursors to the event, plant response and follow-up, radiological considerations, regulatory process considerations and safety significance. The root cause of event is recognized when there is no known answer on question 'why has it happened?' regarding relevant condition that may have affected the event. At that point the Olef is proceeding by actions taken in response to events, utilization, dissemination and exchange of operating experience information and at the end reviewing the effectiveness of the Olef. Analysis of the event and the selection of recommended corrective/preventive actions for implementation and prioritization can be enhanced by taking into account the information and insights derived from Pasa-based analysis. A Pasa based method, called probabilistic precursor event analysis (PPE A) provides a complement to the RCA approach by focusing on how an event might have developed adversely, and implies the mapping of an operational event on a probabilistic risk model of the plant in order to obtain a quantitative assessment of the safety significance of the event PSA based event analysis provides, due to its quantitative nature, appropriate prioritization of corrective actions. PPEA defines requirements for PSA model and code, identifies input requirements and elaborates following

  9. Comparison of neurosphere-like cell clusters derived from dental follicle precursor cells and retinal Müller cells

    DEFF Research Database (Denmark)

    Beck, Hans Christian; Petersen, Jørgen; Felthaus, Oliver

    2011-01-01

    Unrelated cells such as dental follicle precursor cells (DFPCs) and retinal Müller cells (MCs) make spheres after cultivation in serum-replacement medium (SRM). Until today, the relation and molecular processes of sphere formation from different cell types remain undescribed. Thus in this study we...... compared proteomes of spheres derived from MCs and DFPCs. 73% of 676 identified proteins were similar expressed in both cell types and many of them are expressed in the brain (55%). Moreover proteins are overrepresented that are associated with pathways for neural diseases such as Huntington disease...... or Alzheimer disease. Interestingly up-regulated proteins in DFPCs are involved in the biosynthesis of glycosphingolipids. These lipids are components of gangliosides such as GD3, which is a novel neural stem cell marker. In conclusion spheres from different types of cells have highly similar proteomes...

  10. Synthesis on accumulation of putative neurotransmitters by cultured neural crest cells

    International Nuclear Information System (INIS)

    Maxwell, G.D.; Sietz, P.D.; Rafford, C.E.

    1982-01-01

    The events mediating the differentiation of embryonic neural crest cells into several types of neurons are incompletely understood. In order to probe one aspect of this differentiation, we have examined the capacity of cultured quail trunk neural crest cells to synthesize, from radioactive precursors, and store several putative neurotransmitter compounds. These neural crest cultures develop the capacity to synthesize and accumulate acetylcholine and the catecholamines norepinephrine and dopamine. In contrast, detectable but relatively little synthesis and accumulation of 5-hydroxytryptamine gamma-aminobutyric acid, or octopamine from the appropriate radiolabeled precursors were observed. The capacity for synthesis and accumulation of radiolabeled acetylcholine and catecholamines is very low or absent at 2 days in vitro. Between 3 and 7 days in vitro, there is a marked rise in both catecholamine and acetylcholine accumulation in the cultures. These findings suggest that, under the particular conditions used in these experiments, the development of neurotransmitter biosynthesis in trunk neural crest cells ijs restricted and resembles, at least partially, the pattern observed in vivo. The development of this capacity to synthesize and store radiolabeled acetylcholine and catecholamines from the appropriate radioactive precursors coincides closely with the development of the activities of the synthetic enzymes choline acetyltransferase and dopamine beta-hydroxylase reported by others

  11. Geometrizing configurations. Heinrich Hertz and his mathematical precursors

    DEFF Research Database (Denmark)

    Lützen, Jesper

    1999-01-01

    A comparison between the methods used by Heinrich hertz and his mathematician precursors such as Liouville, Lipschitz and Darboux in order to apply differential geometry in mechanics......A comparison between the methods used by Heinrich hertz and his mathematician precursors such as Liouville, Lipschitz and Darboux in order to apply differential geometry in mechanics...

  12. The electromagnetic Brillouin precursor in one-dimensional photonic crystals

    NARCIS (Netherlands)

    Uitham, R.; Hoenders, B. J.

    2008-01-01

    We have calculated the electromagnetic Brillouin precursor that arises in a one-dimensional photonic crystal that consists of two homogeneous slabs which each have a single electron resonance. This forerunner is compared with the Brillouin precursor that arises in a homogeneous double-electron

  13. Dynamic stabilization of disruption precursors in tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Maoquan, Wang; Jianshan, Mao; Yuan, Pan [Academia Sinica, Hefei, AH (China). Inst. of Plasma Physics

    1994-12-01

    A method for dynamic stabilization of the disruption precursors in tokamak is proposed, that is a controlled ac current induced and added to the equilibrium current. The ac currents applied can be a sine alternative current with a relevant frequency, or a pulsed current with a suitable pulsed width {tau} and or a discontinuous pulsed current whose width {tau} is very shorter than the intervals between pulses, and or a `sawtooth` pulsed current with the time of ramp phase of the sawtooth is very much shorter than the sawtooth descending time, the ratio of them can be {<=}10{sup -3}. The physical model of the ac current drive is analyzed in detail. The suppression role of the ac current on the MHD perturbations was analyzed in theory and proved numerically. It is indicated that the ac current can make the discontinuous derivative, {Delta}`, more favorable for the tearing mode stabilities, and so, as long as the parameters of the applied ac currents are selected suitably, the MHD perturbations can be suppressed effectively, the perturbations will be in the zero-growing state, the profile of the plasma current and temperature remain in the initial states and not variate basically, the tokamak be in the stabilized operation state. (8 figs.).

  14. Assimilation of NAD(+) precursors in Candida glabrata.

    Science.gov (United States)

    Ma, Biao; Pan, Shih-Jung; Zupancic, Margaret L; Cormack, Brendan P

    2007-10-01

    The yeast pathogen Candida glabrata is a nicotinamide adenine dinucleotide (NAD(+)) auxotroph and its growth depends on the environmental supply of vitamin precursors of NAD(+). C. glabrata salvage pathways defined in this article allow NAD(+) to be synthesized from three compounds - nicotinic acid (NA), nicotinamide (NAM) and nicotinamide riboside (NR). NA is salvaged through a functional Preiss-Handler pathway. NAM is first converted to NA by nicotinamidase and then salvaged by the Preiss-Handler pathway. Salvage of NR in C. glabrata occurs via two routes. The first, in which NR is phosphorylated by the NR kinase Nrk1, is independent of the Preiss-Handler pathway. The second is a novel pathway in which NR is degraded by the nucleosidases Pnp1 and Urh1, with a minor role for Meu1, and ultimately converted to NAD(+) via the nicotinamidase Pnc1 and the Preiss-Handler pathway. Using C. glabrata mutants whose growth depends exclusively on the external NA or NR supply, we also show that C. glabrata utilizes NR and to a lesser extent NA as NAD(+) sources during disseminated infection.

  15. Modelling earth current precursors in earthquake prediction

    Directory of Open Access Journals (Sweden)

    R. Di Maio

    1997-06-01

    Full Text Available This paper deals with the theory of earth current precursors of earthquake. A dilatancy-diffusion-polarization model is proposed to explain the anomalies of the electric potential, which are observed on the ground surface prior to some earthquakes. The electric polarization is believed to be the electrokinetic effect due to the invasion of fluids into new pores, which are opened inside a stressed-dilated rock body. The time and space variation of the distribution of the electric potential in a layered earth as well as in a faulted half-space is studied in detail. It results that the surface response depends on the underground conductivity distribution and on the relative disposition of the measuring dipole with respect to the buried bipole source. A field procedure based on the use of an areal layout of the recording sites is proposed, in order to obtain the most complete information on the time and space evolution of the precursory phenomena in any given seismic region.

  16. Enzymatic synthesis of vitamin B6 precursor

    Directory of Open Access Journals (Sweden)

    Prlainović Nevena Ž.

    2013-01-01

    Full Text Available 3-Cyano-4-ethoxymethyl-6-methyl-2-pyridone is an important precursor in the synthesis of vitamin B6, obtained in the addition reaction between 2-cyanoacetamide and 1-ethoxy-2,4-pentanedione catalyzed by lipase from Candida rugosa (triacylglycerol ester hydrolases, EC 3.1.1.3. This work shows new experimental data and mathematical modeling of lipase catalyzed synthesis of 3-cyano-4-ethoxymethyl-6-methyl-2-pyridone, starting from 1-ethoxy-2,4-pentanedione and 2-cyanoacetamide. Kinetic measurements were done at 50 oC with enzyme concentration of 1.2 % w/v. Experimental results were fitted with two kinetic models: the ordered bi-ter and ping-pong bi-ter model, and the initial rates of the reaction were found to correlate best with a ping-pong bi-ter mechanism with inhibition by 2-cyanoacetamide. Obtained specificity constants indicated that lipase from C. rugosa had higher affinity towards 1-ethoxy-2,4-pentanedione and less bulky substrates. [Projekat Ministarstva nauke Republike Srbije, br. 172013, br. III 46010 and br. 172049

  17. Earth Observing System precursor data sets

    Science.gov (United States)

    Mah, Grant R.; Eidenshink, Jeff C.; Sheffield, K. W.; Myers, Jeffrey S.

    1993-08-01

    The Land Processes Distributed Active Archive Center (DAAC) is archiving and processing precursor data from airborne and spaceborne instruments such as the thermal infrared multispectral scanner (TIMS), the NS-001 and thematic mapper simulators (TMS), and the advanced very high resolution radiometer (AVHRR). The instrument data are being used to construct data sets that simulate the spectral and spatial characteristics of the advanced spaceborne thermal emission and reflection radiometer (ASTER) and the moderate resolution imaging spectrometer (MODIS) flight instruments scheduled to be flown on the EOS-AM spacecraft. Ames Research Center has developed and is flying a MODIS airborne simulator (MAS), which provides coverage in both MODIS and ASTER bands. A simulation of an ASTER data set over Death Valley, California has been constructed using a combination of TMS and TIMS data, along with existing digital elevation models that were used to develop the topographic information. MODIS data sets are being simulated by using MAS for full-band site coverage at high resolution and AVHRR for global coverage at 1 km resolution.

  18. PRECURSORS TO INTERSTELLAR SHOCKS OF SOLAR ORIGIN

    Energy Technology Data Exchange (ETDEWEB)

    Gurnett, D. A.; Kurth, W. S. [University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242 (United States); Stone, E. C.; Cummings, A. C. [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Krimigis, S. M.; Decker, R. B. [Applied Physics Laboratory/JHU, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Ness, N. F. [Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064 (United States); Burlaga, L. F., E-mail: donald-gurnett@uiowa.edu [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States)

    2015-08-20

    On or about 2012 August 25, the Voyager 1 spacecraft crossed the heliopause into the nearby interstellar plasma. In the nearly three years that the spacecraft has been in interstellar space, three notable particle and field disturbances have been observed, each apparently associated with a shock wave propagating outward from the Sun. Here, we present a detailed analysis of the third and most impressive of these disturbances, with brief comparisons to the two previous events, both of which have been previously reported. The shock responsible for the third event was first detected on 2014 February 17 by the onset of narrowband radio emissions from the approaching shock, followed on 2014 May 13 by the abrupt appearance of intense electron plasma oscillations generated by electrons streaming outward ahead of the shock. Finally, the shock arrived on 2014 August 25, as indicated by a jump in the magnetic field strength and the plasma density. Various disturbances in the intensity and anisotropy of galactic cosmic rays were also observed ahead of the shock, some of which are believed to be caused by the reflection and acceleration of cosmic rays by the magnetic field jump at the shock, and/or by interactions with upstream plasma waves. Comparisons to the two previous weaker events show somewhat similar precursor effects, although differing in certain details. Many of these effects are very similar to those observed in the region called the “foreshock” that occurs upstream of planetary bow shocks, only on a vastly larger spatial scale.

  19. Innate lymphoid cells, precursors and plasticity.

    Science.gov (United States)

    Gronke, Konrad; Kofoed-Nielsen, Michael; Diefenbach, Andreas

    2016-11-01

    Innate lymphoid cells (ILC) have only recently been recognized as a separate entity of the lymphoid lineage. Their subpopulations share common characteristics in terms of early development and major transcriptional circuitry with their related cousins of the T cell world. It is currently hypothesized that ILCs constitute an evolutionary older version of the lymphoid immune system. They are found at all primary entry points for pathogens such as mucosal surfaces of the lung and gastrointestinal system, the skin and the liver, which is the central contact point for pathogens that breach the intestinal barrier and enter the circulation. There, ILC contribute to the first line defense as well as to organ homeostasis. However, ILC are not only involved in classical defense tasks, but also contribute to the organogenesis of lymphoid organs as well as tissue remodeling and even stem cell regeneration. ILC may, therefore, implement different functions according to their emergence in ontogeny, their development and their final tissue location. We will review here their early development from precursors of the fetal liver and the adult bone marrow as well as their late plasticity in adaptation to their environment. Copyright © 2016 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.

  20. Identification, Selection, and Enrichment of Cardiomyocyte Precursors

    Directory of Open Access Journals (Sweden)

    Bianca Ferrarini Zanetti

    2013-01-01

    Full Text Available The large-scale production of cardiomyocytes is a key step in the development of cell therapy and tissue engineering to treat cardiovascular diseases, particularly those caused by ischemia. The main objective of this study was to establish a procedure for the efficient production of cardiomyocytes by reprogramming mesenchymal stem cells from adipose tissue. First, lentiviral vectors expressing neoR and GFP under the control of promoters expressed specifically during cardiomyogenesis were constructed to monitor cell reprogramming into precardiomyocytes and to select cells for amplification and characterization. Cellular reprogramming was performed using 5′-azacytidine followed by electroporation with plasmid pOKS2a, which expressed Oct4, Sox2, and Klf4. Under these conditions, GFP expression began only after transfection with pOKS2a, and less than 0.015% of cells were GFP+. These GFP+ cells were selected for G418 resistance to find molecular markers of cardiomyocytes by RT-PCR and immunocytochemistry. Both genetic and protein markers of cardiomyocytes were present in the selected cells, with some variations among them. Cell doubling time did not change after selection. Together, these results indicate that enrichment with vectors expressing GFP and neoR under cardiomyocyte-specific promoters can produce large numbers of cardiomyocyte precursors (CMPs, which can then be differentiated terminally for cell therapy and tissue engineering.

  1. Parallel consensual neural networks.

    Science.gov (United States)

    Benediktsson, J A; Sveinsson, J R; Ersoy, O K; Swain, P H

    1997-01-01

    A new type of a neural-network architecture, the parallel consensual neural network (PCNN), is introduced and applied in classification/data fusion of multisource remote sensing and geographic data. The PCNN architecture is based on statistical consensus theory and involves using stage neural networks with transformed input data. The input data are transformed several times and the different transformed data are used as if they were independent inputs. The independent inputs are first classified using the stage neural networks. The output responses from the stage networks are then weighted and combined to make a consensual decision. In this paper, optimization methods are used in order to weight the outputs from the stage networks. Two approaches are proposed to compute the data transforms for the PCNN, one for binary data and another for analog data. The analog approach uses wavelet packets. The experimental results obtained with the proposed approach show that the PCNN outperforms both a conjugate-gradient backpropagation neural network and conventional statistical methods in terms of overall classification accuracy of test data.

  2. Skin derived precursor Schwann cell-generated acellular matrix modified chitosan/silk scaffolds for bridging rat sciatic nerve gap.

    Science.gov (United States)

    Zhu, Changlai; Huang, Jing; Xue, Chengbin; Wang, Yaxian; Wang, Shengran; Bao, Shuangxi; Chen, Ruyue; Li, Yuan; Gu, Yun

    2017-12-27

    Extracellular/acellular matrix has been attracted much research interests for its unique biological characteristics, and ACM modified neural scaffolds shows the remarkable role of promoting peripheral nerve regeneration. In this study, skin-derived precursors pre-differentiated into Schwann cells (SKP-SCs) were used as parent cells to generate acellular(ACM) for constructing a ACM-modified neural scaffold. SKP-SCs were co-cultured with chitosan nerve guidance conduits (NGC) and silk fibroin filamentous fillers, followed by decellularization to stimulate ACM deposition. This NGC-based, SKP-SC-derived ACM-modified neural scaffold was used for bridging a 10 mm long rat sciatic nerve gap. Histological and functional evaluation after grafting demonstrated that regenerative outcomes achieved by this engineered neural scaffold were better than those achieved by a plain chitosan-silk fibroin scaffold, and suggested the benefits of SKP-SC-derived ACM for peripheral nerve repair. Copyright © 2017 Elsevier Ireland Ltd and Japan Neuroscience Society. All rights reserved.

  3. Msx genes define a population of mural cell precursors required for head blood vessel maturation.

    Science.gov (United States)

    Lopes, Miguel; Goupille, Olivier; Saint Cloment, Cécile; Lallemand, Yvan; Cumano, Ana; Robert, Benoît

    2011-07-01

    Vessels are primarily formed from an inner endothelial layer that is secondarily covered by mural cells, namely vascular smooth muscle cells (VSMCs) in arteries and veins and pericytes in capillaries and veinules. We previously showed that, in the mouse embryo, Msx1(lacZ) and Msx2(lacZ) are expressed in mural cells and in a few endothelial cells. To unravel the role of Msx genes in vascular development, we have inactivated the two Msx genes specifically in mural cells by combining the Msx1(lacZ), Msx2(lox) and Sm22α-Cre alleles. Optical projection tomography demonstrated abnormal branching of the cephalic vessels in E11.5 mutant embryos. The carotid and vertebral arteries showed an increase in caliber that was related to reduced vascular smooth muscle coverage. Taking advantage of a newly constructed Msx1(CreERT2) allele, we demonstrated by lineage tracing that the primary defect lies in a population of VSMC precursors. The abnormal phenotype that ensues is a consequence of impaired BMP signaling in the VSMC precursors that leads to downregulation of the metalloprotease 2 (Mmp2) and Mmp9 genes, which are essential for cell migration and integration into the mural layer. Improper coverage by VSMCs secondarily leads to incomplete maturation of the endothelial layer. Our results demonstrate that both Msx1 and Msx2 are required for the recruitment of a population of neural crest-derived VSMCs.

  4. Differences in Neural Correlates of Speech Perception in 3 Month Olds at High and Low Risk for Autism Spectrum Disorder

    Science.gov (United States)

    Edwards, Laura A.; Wagner, Jennifer B.; Tager-Flusberg, Helen; Nelson, Charles A.

    2017-01-01

    In this study, we investigated neural precursors of language acquisition as potential endophenotypes of autism spectrum disorder (ASD) in 3-month-old infants at high and low familial ASD risk. Infants were imaged using functional near-infrared spectroscopy while they listened to auditory stimuli containing syllable repetitions; their neural…

  5. A subpopulation of smooth muscle cells, derived from melanocyte-competent precursors, prevents patent ductus arteriosus.

    Directory of Open Access Journals (Sweden)

    Ichiro Yajima

    Full Text Available BACKGROUND: Patent ductus arteriosus is a life-threatening condition frequent in premature newborns but also present in some term infants. Current mouse models of this malformation generally lead to perinatal death, not reproducing the full phenotypic spectrum in humans, in whom genetic inheritance appears complex. The ductus arteriosus (DA, a temporary fetal vessel that bypasses the lungs by shunting the aortic arch to the pulmonary artery, is constituted by smooth muscle cells of distinct origins (SMC1 and SMC2 and many fewer melanocytes. To understand novel mechanisms preventing DA closure at birth, we evaluated the importance of cell fate specification in SMC that form the DA during embryonic development. Upon specific Tyr::Cre-driven activation of Wnt/β-catenin signaling at the time of cell fate specification, melanocytes replaced the SMC2 population of the DA, suggesting that SMC2 and melanocytes have a common precursor. The number of SMC1 in the DA remained similar to that in controls, but insufficient to allow full DA closure at birth. Thus, there was no cellular compensation by SMC1 for the loss of SMC2. Mice in which only melanocytes were genetically ablated after specification from their potential common precursor with SMC2, demonstrated that differentiated melanocytes themselves do not affect DA closure. Loss of the SMC2 population, independent of the presence of melanocytes, is therefore a cause of patent ductus arteriosus and premature death in the first months of life. Our results indicate that patent ductus arteriosus can result from the insufficient differentiation, proliferation, or contractility of a specific smooth muscle subpopulation that shares a common neural crest precursor with cardiovascular melanocytes.

  6. A Subpopulation of Smooth Muscle Cells, Derived from Melanocyte-Competent Precursors, Prevents Patent Ductus Arteriosus

    Science.gov (United States)

    Puig, Isabel; Champeval, Delphine; Kumasaka, Mayuko; Belloir, Elodie; Bonaventure, Jacky; Mark, Manuel; Yamamoto, Hiroaki; Taketo, Mark M.; Choquet, Philippe; Etchevers, Heather C.; Beermann, Friedrich; Delmas, Véronique; Monassier, Laurent; Larue, Lionel

    2013-01-01

    Background Patent ductus arteriosus is a life-threatening condition frequent in premature newborns but also present in some term infants. Current mouse models of this malformation generally lead to perinatal death, not reproducing the full phenotypic spectrum in humans, in whom genetic inheritance appears complex. The ductus arteriosus (DA), a temporary fetal vessel that bypasses the lungs by shunting the aortic arch to the pulmonary artery, is constituted by smooth muscle cells of distinct origins (SMC1 and SMC2) and many fewer melanocytes. To understand novel mechanisms preventing DA closure at birth, we evaluated the importance of cell fate specification in SMC that form the DA during embryonic development. Upon specific Tyr::Cre-driven activation of Wnt/β-catenin signaling at the time of cell fate specification, melanocytes replaced the SMC2 population of the DA, suggesting that SMC2 and melanocytes have a common precursor. The number of SMC1 in the DA remained similar to that in controls, but insufficient to allow full DA closure at birth. Thus, there was no cellular compensation by SMC1 for the loss of SMC2. Mice in which only melanocytes were genetically ablated after specification from their potential common precursor with SMC2, demonstrated that differentiated melanocytes themselves do not affect DA closure. Loss of the SMC2 population, independent of the presence of melanocytes, is therefore a cause of patent ductus arteriosus and premature death in the first months of life. Our results indicate that patent ductus arteriosus can result from the insufficient differentiation, proliferation, or contractility of a specific smooth muscle subpopulation that shares a common neural crest precursor with cardiovascular melanocytes. PMID:23382837

  7. Interleukin-6 Regulates Adult Neural Stem Cell Numbers during Normal and Abnormal Post-natal Development

    Directory of Open Access Journals (Sweden)

    Mekayla A. Storer

    2018-05-01

    Full Text Available Summary: Circulating systemic factors can regulate adult neural stem cell (NSC biology, but the identity of these circulating cues is still being defined. Here, we have focused on the cytokine interleukin-6 (IL-6, since increased circulating levels of IL-6 are associated with neural pathologies such as autism and bipolar disorder. We show that IL-6 promotes proliferation of post-natal murine forebrain NSCs and that, when the IL-6 receptor is inducibly knocked out in post-natal or adult neural precursors, this causes a long-term decrease in forebrain NSCs. Moreover, a transient circulating surge of IL-6 in perinatal or adult mice causes an acute increase in neural precursor proliferation followed by long-term depletion of adult NSC pools. Thus, IL-6 signaling is both necessary and sufficient for adult NSC self-renewal, and acute perturbations in circulating IL-6, as observed in many pathological situations, have long-lasting effects on the size of adult NSC pools. : In this report, Storer and colleagues demonstrate that the circulating cytokine IL-6, which is elevated in humans in different pathological situations, can perturb neural stem cell biology after birth. They show that IL-6 signaling is essential for self-renewal and maintenance of post-natal and adult NSCs in the murine forebrain under normal homeostatic conditions. Keywords: interleukin-6, neural stem cell, adult neurogenesis, CNS cytokines, postnatal brain development, stem cell depletion, neural stem cell niche, circulating stem cell factors, olfactory bulb

  8. Neural Architectures for Control

    Science.gov (United States)

    Peterson, James K.

    1991-01-01

    The cerebellar model articulated controller (CMAC) neural architectures are shown to be viable for the purposes of real-time learning and control. Software tools for the exploration of CMAC performance are developed for three hardware platforms, the MacIntosh, the IBM PC, and the SUN workstation. All algorithm development was done using the C programming language. These software tools were then used to implement an adaptive critic neuro-control design that learns in real-time how to back up a trailer truck. The truck backer-upper experiment is a standard performance measure in the neural network literature, but previously the training of the controllers was done off-line. With the CMAC neural architectures, it was possible to train the neuro-controllers on-line in real-time on a MS-DOS PC 386. CMAC neural architectures are also used in conjunction with a hierarchical planning approach to find collision-free paths over 2-D analog valued obstacle fields. The method constructs a coarse resolution version of the original problem and then finds the corresponding coarse optimal path using multipass dynamic programming. CMAC artificial neural architectures are used to estimate the analog transition costs that dynamic programming requires. The CMAC architectures are trained in real-time for each obstacle field presented. The coarse optimal path is then used as a baseline for the construction of a fine scale optimal path through the original obstacle array. These results are a very good indication of the potential power of the neural architectures in control design. In order to reach as wide an audience as possible, we have run a seminar on neuro-control that has met once per week since 20 May 1991. This seminar has thoroughly discussed the CMAC architecture, relevant portions of classical control, back propagation through time, and adaptive critic designs.

  9. A critical review of Electric Earthquake Precursors

    Directory of Open Access Journals (Sweden)

    F. Vallianatos

    2001-06-01

    Full Text Available The generation of transient electric potential prior to rupture has been demonstrated in a number of laboratory experiments involving both dry and wet rock specimens. Several different electrification effects are responsible for these observations, but how these may scale up co-operatively in large heterogeneous rock volumes, to produce observable macroscopic signals, is still incompletely understood. Accordingly, the nature and properties of possible Electric Earthquake Precursors (EEP are still inadequately understood. For a long time observations have been fragmentary, narrow band and oligo-parametric (for instance, the magnetic field was not routinely measured. In general, the discrimination of purported EEP signals relied on "experience" and ad hoc empirical rules that could be shown unable to guarantee the validity of the data. In consequence, experimental studies have produced a prolific variety of signal shape, complexity and duration but no explanation for the apparently indefinite diversity. A set of inconsistent or conflicting ideas attempted to explain such observations, including different concepts about the EEP source region (near the observer or at the earthquake focus and propagation (frequently assumed to be guided by peculiar geoelectric structure. Statistics was also applied to establish the "beyond chance" association between presumed EEP signals and earthquakes. In the absence of well constrained data, this approach ended up with intense debate and controversy but no useful results. The response of the geophysical community was scepticism and by the mid-90's, the very existence of EEP was debated. At that time, a major re-thinking of EEP research began to take place, with reformulation of its queries and objectives and refocusing on the exploration of fundamental concepts, less on field experiments. The first encouraging results began to appear in the last two years of the 20th century. Observation technologies are mature

  10. A critical review of electric earthquake precursors

    Energy Technology Data Exchange (ETDEWEB)

    Tzanis, A. [Athens Univ., Athens (Italy). Dept. of Geophysics and Geothermy; Valliantos, F. [Technological Educational Institute of Crete, Chania (Greece)

    2001-04-01

    The generation of transient electric potential prior to rupture has been demonstrated in a number of laboratory experiments involving both dry and wet rock specimens. Several different electrification effects are responsible for these observations, but how these may scale up co-operatively in large heterogeneous rock volumes, to produce observable macroscopic signals, is still incompletely understood. Accordingly, the nature and properties of possible Electric Earthquake Precursors (EEP) are still inadequately understood. For a long time observations have been fragmentary, narrow band and oligo-parametric (for instance, the magnetic field was not routinely measured). In general, the discrimination of purported EEP signals relied on experience and ad hoc empirical rules that could be shown unable to guarantee the validity of the data. In consequence, experimental studies have produced a prolific variety of signal shape, complexity and duration but no explanation for the apparently indefinite diversity. A set of inconsistent or conflicting ideas attempted to explain such observations, including different concepts about the EEP source region (near the observer or at the earthquake focus) and propagation (frequently assumed to be guided by peculiar geo electric structure). Statistics was also applied to establish the beyond chance association between presumed EEP signals and earthquakes. In the absence of well constrained data, this approach ended up with intense debate and controversy but no useful results. The response of the geophysical community was scepticism and by the mid-90's, the very existence of EEP was debated. At that time, a major re-thinking of EEP research began to take place, with reformulation of its queries and objectives and refocusing on the exploration of fundamental concepts, less on field experiments. The firs encouraging results began to appear in the last two years of the 20th century. Observation technologies are mature and can guarantee

  11. PRECOMBUSTION REMOVAL OF HAZARDOUS AIR POLLUTANT PRECURSORS

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    2000-10-09

    In response to growing environmental concerns reflected in the 1990 Clean Air Act Amendment (CAAA), the United States Department of Energy (DOE) sponsored several research and development projects in late 1995 as part of an initiative entitled Advanced Environmental Control Technologies for Coal-Based Power Systems. The program provided cost-shared support for research and development projects that could accelerate the commercialization of affordable, high-efficiency, low-emission, coal-fueled electric generating technologies. Clean coal technologies developed under this program would serve as prototypes for later generations of technologies to be implemented in the industrial sector. In order to identify technologies with the greatest potential for commercial implementation, projects funded under Phase I of this program were subject to competitive review by DOE before being considered for continuation funding under Phase II. One of the primary topical areas identified under the DOE initiative relates to the development of improved technologies for reducing the emissions of air toxics. Previous studies have suggested that many of the potentially hazardous air pollutant precursors (HAPPs) occur as trace elements in the mineral matter of run-of-mine coals. As a result, these elements have the potential to be removed prior to combustion at the mine site by physical coal cleaning processes (i.e., coal preparation). Unfortunately, existing coal preparation plants are generally limited in their ability to remove HAPPs due to incomplete liberation of the mineral matter and high organic associations of some trace elements. In addition, existing physical coal cleaning plants are not specifically designed or optimized to ensure that high trace element rejections may be achieved.

  12. On important precursor of singular optics (tutorial)

    Science.gov (United States)

    Polyanskii, Peter V.; Felde, Christina V.; Bogatyryova, Halina V.; Konovchuk, Alexey V.

    2018-01-01

    The rise of singular optics is usually associated with the seminal paper by J. F. Nye and M. V. Berry [Proc. R. Soc. Lond. A, 336, 165-189 (1974)]. Intense development of this area of modern photonics has started since the early eighties of the XX century due to invention of the interfrence technique for detection and diagnostics of phase singularities, such as optical vortices in complex speckle-structured light fields. The next powerful incentive for formation of singular optics into separate area of the science on light was connectected with discovering of very practical technique for creation of singular optical beams of various kinds on the base of computer-generated holograms. In the eghties and ninetieth of the XX century, singular optics evolved, almost entirely, under the approximation of complete coherency of light field. Only at the threshold of the XXI century, it has been comprehended that the singular-optics approaches can be fruitfully expanded onto partially spatially coherent, partially polarized and polychromatic light fields supporting singularities of new kinds, that has been resulted in establishing of correlation singular optics. Here we show that correlation singular optics has much deeper roots, ascending to "pre-singular" and even pre-laser epoch and associated with the concept of partial coherence and polarization. It is remarcable that correlation singular optics in its present interpretation has forestalled the standard coherent singular optics. This paper is timed to the sixtieth anniversary of the most profound precursor of modern correlation singular optics [J. Opt. Soc. Am., 47, 895-902 (1957)].

  13. Sacred or Neural?

    DEFF Research Database (Denmark)

    Runehov, Anne Leona Cesarine

    Are religious spiritual experiences merely the product of the human nervous system? Anne L.C. Runehov investigates the potential of contemporary neuroscience to explain religious experiences. Following the footsteps of Michael Persinger, Andrew Newberg and Eugene d'Aquili she defines...... the terminological bounderies of "religious experiences" and explores the relevant criteria for the proper evaluation of scientific research, with a particular focus on the validity of reductionist models. Runehov's theis is that the perspectives looked at do not necessarily exclude each other but can be merged....... The question "sacred or neural?" becomes a statement "sacred and neural". The synergies thus produced provide manifold opportunities for interdisciplinary dialogue and research....

  14. Deconvolution using a neural network

    Energy Technology Data Exchange (ETDEWEB)

    Lehman, S.K.

    1990-11-15

    Viewing one dimensional deconvolution as a matrix inversion problem, we compare a neural network backpropagation matrix inverse with LMS, and pseudo-inverse. This is a largely an exercise in understanding how our neural network code works. 1 ref.

  15. Introduction to Artificial Neural Networks

    DEFF Research Database (Denmark)

    Larsen, Jan

    1999-01-01

    The note addresses introduction to signal analysis and classification based on artificial feed-forward neural networks.......The note addresses introduction to signal analysis and classification based on artificial feed-forward neural networks....

  16. Magnetic reconnection and precursor effect in coaxial discharge

    International Nuclear Information System (INIS)

    Masoud, M.M.; Soliman, H.M.; El-Khalafawy, T.A.

    1988-01-01

    A precursor pulse was observed ahead of the plasma sheath produced by a coaxial electrode discharge system. The velocity of the precursor pulse was 4x10 7 cmS -1 and the velocity of the plasma sheath was 6x10 6 cmS -1 . The precursor pulse was unaffected when an axial magnetic field of 6 K.G. was applied to the propagation chamber, while the plasma sheath velocity increased and downstream structure were changed. The precursor pulse was split, sometimes, into two or more peaks, had the same shape and structure of the original one. The rest gas was heated up to 20 e.V. when the precursor pulse was destructed. The precursor pulse propagation mechanism and parameters showed that it had a solitary wave structure and behaviour. A reversed magnetic field was detected, when the plasma sheath had diamagnetic properties, where magnetic reconnection took place. Magnetic reconnection was responsible for energy transfiguration and wave generation. This was due to acceleration mechanism of charged particles occurred by the induced electric field at the moment of magnetic reconnection. The detected induced electric field had a high field intensity and fast rise time pulse. Several instabilities were referred to magnetic reconnection and the precursor pulse observed was a result of such instabilities

  17. Differences in Neural Correlates of Speech Perception in 3 Month Olds at High and Low Risk for Autism Spectrum Disorder.

    Science.gov (United States)

    Edwards, Laura A; Wagner, Jennifer B; Tager-Flusberg, Helen; Nelson, Charles A

    2017-10-01

    In this study, we investigated neural precursors of language acquisition as potential endophenotypes of autism spectrum disorder (ASD) in 3-month-old infants at high and low familial ASD risk. Infants were imaged using functional near-infrared spectroscopy while they listened to auditory stimuli containing syllable repetitions; their neural responses were analyzed over left and right temporal regions. While female low risk infants showed initial neural activation that decreased over exposure to repetition-based stimuli, potentially indicating a habituation response to repetition in speech, female high risk infants showed no changes in neural activity over exposure. This finding may indicate a potential neural endophenotype of language development or ASD specific to females at risk for the disorder.

  18. Methods for forming particles from single source precursors

    Science.gov (United States)

    Fox, Robert V [Idaho Falls, ID; Rodriguez, Rene G [Pocatello, ID; Pak, Joshua [Pocatello, ID

    2011-08-23

    Single source precursors are subjected to carbon dioxide to form particles of material. The carbon dioxide may be in a supercritical state. Single source precursors also may be subjected to supercritical fluids other than supercritical carbon dioxide to form particles of material. The methods may be used to form nanoparticles. In some embodiments, the methods are used to form chalcopyrite materials. Devices such as, for example, semiconductor devices may be fabricated that include such particles. Methods of forming semiconductor devices include subjecting single source precursors to carbon dioxide to form particles of semiconductor material, and establishing electrical contact between the particles and an electrode.

  19. Neural Network Ensembles

    DEFF Research Database (Denmark)

    Hansen, Lars Kai; Salamon, Peter

    1990-01-01

    We propose several means for improving the performance an training of neural networks for classification. We use crossvalidation as a tool for optimizing network parameters and architecture. We show further that the remaining generalization error can be reduced by invoking ensembles of similar...... networks....

  20. Neural correlates of consciousness

    African Journals Online (AJOL)

    neural cells.1 Under this approach, consciousness is believed to be a product of the ... possible only when the 40 Hz electrical hum is sustained among the brain circuits, ... expect the brain stem ascending reticular activating system. (ARAS) and the ... related synchrony of cortical neurons.11 Indeed, stimulation of brainstem ...

  1. Neural Networks and Micromechanics

    Science.gov (United States)

    Kussul, Ernst; Baidyk, Tatiana; Wunsch, Donald C.

    The title of the book, "Neural Networks and Micromechanics," seems artificial. However, the scientific and technological developments in recent decades demonstrate a very close connection between the two different areas of neural networks and micromechanics. The purpose of this book is to demonstrate this connection. Some artificial intelligence (AI) methods, including neural networks, could be used to improve automation system performance in manufacturing processes. However, the implementation of these AI methods within industry is rather slow because of the high cost of conducting experiments using conventional manufacturing and AI systems. To lower the cost, we have developed special micromechanical equipment that is similar to conventional mechanical equipment but of much smaller size and therefore of lower cost. This equipment could be used to evaluate different AI methods in an easy and inexpensive way. The proved methods could be transferred to industry through appropriate scaling. In this book, we describe the prototypes of low cost microequipment for manufacturing processes and the implementation of some AI methods to increase precision, such as computer vision systems based on neural networks for microdevice assembly and genetic algorithms for microequipment characterization and the increase of microequipment precision.

  2. Introduction to neural networks

    International Nuclear Information System (INIS)

    Pavlopoulos, P.

    1996-01-01

    This lecture is a presentation of today's research in neural computation. Neural computation is inspired by knowledge from neuro-science. It draws its methods in large degree from statistical physics and its potential applications lie mainly in computer science and engineering. Neural networks models are algorithms for cognitive tasks, such as learning and optimization, which are based on concepts derived from research into the nature of the brain. The lecture first gives an historical presentation of neural networks development and interest in performing complex tasks. Then, an exhaustive overview of data management and networks computation methods is given: the supervised learning and the associative memory problem, the capacity of networks, the Perceptron networks, the functional link networks, the Madaline (Multiple Adalines) networks, the back-propagation networks, the reduced coulomb energy (RCE) networks, the unsupervised learning and the competitive learning and vector quantization. An example of application in high energy physics is given with the trigger systems and track recognition system (track parametrization, event selection and particle identification) developed for the CPLEAR experiment detectors from the LEAR at CERN. (J.S.). 56 refs., 20 figs., 1 tab., 1 appendix

  3. Learning from neural control.

    Science.gov (United States)

    Wang, Cong; Hill, David J

    2006-01-01

    One of the amazing successes of biological systems is their ability to "learn by doing" and so adapt to their environment. In this paper, first, a deterministic learning mechanism is presented, by which an appropriately designed adaptive neural controller is capable of learning closed-loop system dynamics during tracking control to a periodic reference orbit. Among various neural network (NN) architectures, the localized radial basis function (RBF) network is employed. A property of persistence of excitation (PE) for RBF networks is established, and a partial PE condition of closed-loop signals, i.e., the PE condition of a regression subvector constructed out of the RBFs along a periodic state trajectory, is proven to be satisfied. Accurate NN approximation for closed-loop system dynamics is achieved in a local region along the periodic state trajectory, and a learning ability is implemented during a closed-loop feedback control process. Second, based on the deterministic learning mechanism, a neural learning control scheme is proposed which can effectively recall and reuse the learned knowledge to achieve closed-loop stability and improved control performance. The significance of this paper is that the presented deterministic learning mechanism and the neural learning control scheme provide elementary components toward the development of a biologically-plausible learning and control methodology. Simulation studies are included to demonstrate the effectiveness of the approach.

  4. Neural systems for control

    National Research Council Canada - National Science Library

    Omidvar, Omid; Elliott, David L

    1997-01-01

    ... is reprinted with permission from A. Barto, "Reinforcement Learning," Handbook of Brain Theory and Neural Networks, M.A. Arbib, ed.. The MIT Press, Cambridge, MA, pp. 804-809, 1995. Chapter 4, Figures 4-5 and 7-9 and Tables 2-5, are reprinted with permission, from S. Cho, "Map Formation in Proprioceptive Cortex," International Jour...

  5. Neural underpinnings of music

    DEFF Research Database (Denmark)

    Vuust, Peter; Gebauer, Line K; Witek, Maria A G

    2014-01-01

    . According to this theory, perception and learning is manifested through the brain’s Bayesian minimization of the error between the input to the brain and the brain’s prior expectations. Fourth, empirical studies of neural and behavioral effects of syncopation, polyrhythm and groove will be reported, and we...

  6. MMPM - Mars MetNet Precursor Mission

    Science.gov (United States)

    Harri, A.-M.; Schmidt, W.; Pichkhadze, K.; Linkin, V.; Vazquez, L.; Uspensky, M.; Polkko, J.; Genzer, M.; Lipatov, A.; Guerrero, H.; Alexashkin, S.; Haukka, H.; Savijarvi, H.; Kauhanen, J.

    2008-09-01

    We are developing a new kind of planetary exploration mission for Mars - MetNet in situ observation network based on a new semi-hard landing vehicle called the Met-Net Lander (MNL). The eventual scope of the MetNet Mission is to deploy some 20 MNLs on the Martian surface using inflatable descent system structures, which will be supported by observations from the orbit around Mars. Currently we are working on the MetNet Mars Precursor Mission (MMPM) to deploy one MetNet Lander to Mars in the 2009/2011 launch window as a technology and science demonstration mission. The MNL will have a versatile science payload focused on the atmospheric science of Mars. Detailed characterization of the Martian atmospheric circulation patterns, boundary layer phenomena, and climatology cycles, require simultaneous in-situ measurements by a network of observation posts on the Martian surface. The scientific payload of the MetNet Mission encompasses separate instrument packages for the atmospheric entry and descent phase and for the surface operation phase. The MetNet mission concept and key probe technologies have been developed and the critical subsystems have been qualified to meet the Martian environmental and functional conditions. Prototyping of the payload instrumentation with final dimensions was carried out in 2003-2006.This huge development effort has been fulfilled in collaboration between the Finnish Meteorological Institute (FMI), the Russian Lavoschkin Association (LA) and the Russian Space Research Institute (IKI) since August 2001. Currently the INTA (Instituto Nacional de Técnica Aeroespacial) from Spain is also participating in the MetNet payload development. To understand the behavior and dynamics of the Martian atmosphere, a wealth of simultaneous in situ observations are needed on varying types of Martian orography, terrain and altitude spanning all latitudes and longitudes. This will be performed by the Mars MetNet Mission. In addition to the science aspects the

  7. [Felice Fontana precursor of neurosciences (author's transl)].

    Science.gov (United States)

    Disertori, B; Piazza, M

    1981-01-01

    The A.A. insert the life and work of the naturalist and chemist Felice Fontana, born in Pomarolo (Trentino), in the frame of 18th century sciences, beside other great names of that century like Carolus Linnaeus, Réaumur, von Haller, Spallanzani, Morgagni, Priestley and Lavoisier. In the field of general biology, the discovery of nucleus and nucleolus and consequently the discovery of the eukaryotic cell, as we say in our days, in his, as well as the one of anabiosis. The A.A. enucleate and analyse the contributions of Fontana to the neurosciences; he has discovered the axon and the myelinic sheath half century before Remak and Purknije; he found out that the white matter of the brain is made of fibres alike those of nerves and the grey matter is made of globules (i.e. cells) mixed up with fibres; he discovered in the retina a part of coming out from the brain; he described the transversal bands of fibres of the skeletal muscles; he was the first to introduce into physiology the law of "all and nothing"; he attributed the irritability to the whole animal life; he identified the pupillar reflexes to the light, the reflex of accommodation, the consensual reflex, the psycho-emotive mydriasis and at last the myosis of sleep. He made experimental searches about nerves and recognised their regeneration, he enumerated various pathological intracranial masses, he made an important anatomopathological research about hydatid cyst in the brain of the sheep affected by "capostorno" and madness, he demonstrated their parasitical nature (he said that the hydated cysts were covered inside by small animals), he come out to formulate the hypothesis that some neuropsychiatric diseases of man can depend from similar aetiology. He declared that passions may have pathological effects (psyco-somatic aetiology), but he has also drawned the attention against the danager of aprioristical generalisation of neurogenical causes in all diseases. The A.A. give to Fontana the palm of precursor

  8. Biological Indicators in Studies of Earthquake Precursors

    Science.gov (United States)

    Sidorin, A. Ya.; Deshcherevskii, A. V.

    2012-04-01

    Time series of data on variations in the electric activity (EA) of four species of weakly electric fish Gnathonemus leopoldianus and moving activity (MA) of two cat-fishes Hoplosternum thoracatum and two groups of Columbian cockroaches Blaberus craniifer were analyzed. The observations were carried out in the Garm region of Tajikistan within the frameworks of the experiments aimed at searching for earthquake precursors. An automatic recording system continuously recorded EA and DA over a period of several years. Hourly means EA and MA values were processed. Approximately 100 different parameters were calculated on the basis of six initial EA and MA time series, which characterize different variations in the EA and DA structure: amplitude of the signal and fluctuations of activity, parameters of diurnal rhythms, correlated changes in the activity of various biological indicators, and others. A detailed analysis of the statistical structure of the total array of parametric time series obtained in the experiment showed that the behavior of all animals shows a strong temporal variability. All calculated parameters are unstable and subject to frequent changes. A comparison of the data obtained with seismicity allow us to make the following conclusions: (1) The structure of variations in the studied parameters is represented by flicker noise or even a more complex process with permanent changes in its characteristics. Significant statistics are required to prove the cause-and-effect relationship of the specific features of such time series with seismicity. (2) The calculation of the reconstruction statistics in the EA and MA series structure demonstrated an increase in their frequency in the last hours or a few days before the earthquake if the hypocenter distance is comparable to the source size. Sufficiently dramatic anomalies in the behavior of catfishes and cockroaches (changes in the amplitude of activity variation, distortions of diurnal rhythms, increase in the

  9. CHEMICAL VAPOUR DEPOSITION FROM A RADIATION-SENSITIVE PRECURSOR

    DEFF Research Database (Denmark)

    2017-01-01

    The present invention relates in one aspect to a method of depositing a thin film on a substrate by chemical vapour deposition (CVD) from a radiation-sensitive precursor substance. The method comprises the steps of: (i) placing the substrate in a reaction chamber of a CVD system; (ii) heating...... heating pulse followed by an idle period; (iii) during at least one of the idle periods, providing a pressure pulse of precursor substance inside the reaction chamber by feeding at least one precursor substance to the reaction chamber so as to establish a reaction partial pressure for thin film deposition...... is formed. According to a further aspect, the invention relates to a chemical vapour deposition (CVD) system for depositing a thin film onto a substrate using precursor substances containing at least one radiation sensitive species....

  10. The proliferative human monocyte subpopulation contains osteoclast precursors

    Science.gov (United States)

    Lari, Roya; Kitchener, Peter D; Hamilton, John A

    2009-01-01

    Introduction Immediate precursors of bone-resorbing osteoclasts are cells of the monocyte/macrophage lineage. Particularly during clinical conditions showing bone loss, it would appear that osteoclast precursors are mobilized from bone marrow into the circulation prior to entering tissues undergoing such loss. The observed heterogeneity of peripheral blood monocytes has led to the notion that different monocyte subpopulations may have special or restricted functions, including as osteoclast precursors. Methods Human peripheral blood monocytes were sorted based upon their degree of proliferation and cultured in macrophage colony-stimulating factor (M-CSF or CSF-1) and receptor activator of nuclear factor-kappa-B ligand (RANKL). Results The monocyte subpopulation that is capable of proliferation gave rise to significantly more multinucleated, bone-resorbing osteoclasts than the bulk of the monocytes. Conclusions Human peripheral blood osteoclast precursors reside in the proliferative monocyte subpopulation. PMID:19222861

  11. Synthesis of beta alumina from aluminum hydroxide and oxyhydroxide precursors

    CSIR Research Space (South Africa)

    Van Zyl, A

    1993-02-01

    Full Text Available Two aluminium oxyhydroxides, boehmite and pseudoboehmite, and two aluminium hydroxides, bayerite and gibbsite, have been investigated as precursors for the synthesis of the solid electrolyte, beta alumina. Reaction pathways and products have been...

  12. Are any public-reported earthquake precursors valid?

    Directory of Open Access Journals (Sweden)

    N. E. Whitehead

    2004-01-01

    Full Text Available This article examines retrospective public-supplied precursor reports statistically, and confirms published hypotheses that some alleged precursors within 100km and within a day prior to the large 1995 Kobe and 1999 Izmit earthquakes, may be valid. The confirmations are mostly at the p<0.001 level of significance. Most significant were alleged meteorological and geophysical precursors, and less often, animal reports. The chi-squared test used, for the first time eliminates the distorting effects of psychological factors on the reports. However it also shows that correct reports are diluted with about the same number which are merely wishful thinking, and obtaining more reliable data would be logistically difficult. Some support is found for another published hypothesis in which other precursors occurred within the ten days prior to the earthquake.

  13. N-Nitroso Compound Precursors in some Nigerian Forage Crops ...

    African Journals Online (AJOL)

    N-Nitroso Compound Precursors in some Nigerian Forage Crops. ... were analyzed as their sulphonamides by gas chromatography interfaced with a chemiluminescence detector-Thermal Energy Analyzer modified for use in nitrogen mode.

  14. Unconsumed precursors and couplers after formation of oxidative hair dyes

    DEFF Research Database (Denmark)

    Rastogi, Suresh Chandra; Søsted, Heidi; Johansen, Jeanne Duus

    2006-01-01

    Contact allergy to hair dye ingredients, especially precursors and couplers, is a well-known entity among consumers having hair colouring done at home or at a hairdresser. The aim of the present investigation was to estimate consumer exposure to some selected precursors (p-phenylenediamine, toluene......-2,5-diamine) and couplers (3-aminophenol, 4-aminophenol, resorcinol) of oxidative hair dyes during and after hair dyeing. Concentrations of unconsumed precursors and couplers in 8 hair dye formulations for non-professional use were investigated, under the conditions reflecting hair dyeing. Oxidative...... hair dye formation in the absence of hair was investigated using 6 products, and 2 products were used for experimental hair dyeing. In both presence and absence of hair, significant amounts of unconsumed precursors and couplers remained in the hair dye formulations after final colour development. Thus...

  15. SEARCH FOR PRECURSOR ERUPTIONS AMONG TYPE IIB SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Strotjohann, Nora L.; Ofek, Eran O.; Gal-Yam, Avishay; Yaron, Ofer [Benoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel); Sullivan, Mark [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Kulkarni, Shrinivas R.; Cao, Yi [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Shaviv, Nir J. [School of Natural Sciences, Institute for Advanced Study, 1 Einstein Drive, Princeton, NJ 08540 (United States); Fremling, Christoffer; Sollerman, Jesper [The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-10691 Stockholm (Sweden); Kasliwal, Mansi M. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Nugent, Peter E. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Arcavi, Iair [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93111 (United States); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Laher, Russ; Surace, Jason [Spitzer Science Center, California Institute of Technology, M/S 314-6, Pasadena, CA 91125 (United States)

    2015-10-01

    The progenitor stars of several Type IIb supernovae (SNe) show indications of extended hydrogen envelopes. These envelopes might be the outcome of luminous energetic pre-explosion events, so-called precursor eruptions. We use the Palomar Transient Factory (PTF) pre-explosion observations of a sample of 27 nearby SNe IIb to look for such precursors during the final years prior to the SN explosion. No precursors are found when combining the observations in 15-day bins, and we calculate the absolute-magnitude-dependent upper limit on the precursor rate. At the 90% confidence level, SNe IIb have on average <0.86 precursors as bright as an absolute R-band magnitude of −14 in the final 3.5 years before the explosion and <0.56 events over the final year. In contrast, precursors among SNe IIn have a ≳5 times higher rate. The kinetic energy required to unbind a low-mass stellar envelope is comparable to the radiated energy of a few-weeks-long precursor that would be detectable for the closest SNe in our sample. Therefore, mass ejections, if they are common in such SNe, are radiatively inefficient or have durations longer than months. Indeed, when using 60-day bins, a faint precursor candidate is detected prior to SN 2012cs (∼2% false-alarm probability). We also report the detection of the progenitor of SN 2011dh that does not show detectable variability over the final two years before the explosion. The suggested progenitor of SN 2012P is still present, and hence is likely a compact star cluster or an unrelated object.

  16. Bioprinting for Neural Tissue Engineering.

    Science.gov (United States)

    Knowlton, Stephanie; Anand, Shivesh; Shah, Twisha; Tasoglu, Savas

    2018-01-01

    Bioprinting is a method by which a cell-encapsulating bioink is patterned to create complex tissue architectures. Given the potential impact of this technology on neural research, we review the current state-of-the-art approaches for bioprinting neural tissues. While 2D neural cultures are ubiquitous for studying neural cells, 3D cultures can more accurately replicate the microenvironment of neural tissues. By bioprinting neuronal constructs, one can precisely control the microenvironment by specifically formulating the bioink for neural tissues, and by spatially patterning cell types and scaffold properties in three dimensions. We review a range of bioprinted neural tissue models and discuss how they can be used to observe how neurons behave, understand disease processes, develop new therapies and, ultimately, design replacement tissues. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Elements of the tsunami precursors' detection physics

    Science.gov (United States)

    Novik, Oleg; Ruzhin, Yuri; Ershov, Sergey; Volgin, Max; Smirnov, Fedor

    ionosphere from the buoy, balloon and satellite complexes. The balloon and buoy complexes will transmit data to a shore station over satellite link. The frequency ranges and sensitivity thresholds of all of the sensors of the LOAMS will be adapted to the characteristics of expected seismic signals according to the numerical research above. Computational methods and statistical analysis (e.g. seismic changes of coherence of spatially distributed sensors of different nature) of the recorded multidimensional time series will be used for prognostic interpretation. The multilevel recordings will provide a stable noise (e.g. ionosphere Pc pulsations, hard sea, industry) and seismic event detection. An intensive heat flow typical for tectonically active lithosphere zones may be considered as an energy source for advanced modifications of the LOAMS. The latter may be used as a warning system for continental and marine technologies, e.g. a sea bottom geothermal energy production. Indeed, seismic distraction of the nuclear power station Fukushima I demonstrates that similar technology hardly is able to solve the energy problems in seismically active regions. On the other hand, the LOAMS may be considered as a scientific observatory for development of the seaquake/tsunami precursor physics, i.e. seismo-hydro-electromagnetics.

  18. Analysis of neural data

    CERN Document Server

    Kass, Robert E; Brown, Emery N

    2014-01-01

    Continual improvements in data collection and processing have had a huge impact on brain research, producing data sets that are often large and complicated. By emphasizing a few fundamental principles, and a handful of ubiquitous techniques, Analysis of Neural Data provides a unified treatment of analytical methods that have become essential for contemporary researchers. Throughout the book ideas are illustrated with more than 100 examples drawn from the literature, ranging from electrophysiology, to neuroimaging, to behavior. By demonstrating the commonality among various statistical approaches the authors provide the crucial tools for gaining knowledge from diverse types of data. Aimed at experimentalists with only high-school level mathematics, as well as computationally-oriented neuroscientists who have limited familiarity with statistics, Analysis of Neural Data serves as both a self-contained introduction and a reference work.

  19. Deep Neural Yodelling

    OpenAIRE

    Pfäffli, Daniel (Autor/in)

    2018-01-01

    Yodel music differs from most other genres by exercising the transition from chest voice to falsetto with an audible glottal stop which is recognised even by laymen. Yodel often consists of a yodeller with a choir accompaniment. In Switzerland, it is differentiated between the natural yodel and yodel songs. Today's approaches to music generation with machine learning algorithms are based on neural networks, which are best described by stacked layers of neurons which are connected with neurons...

  20. Neural networks for triggering

    International Nuclear Information System (INIS)

    Denby, B.; Campbell, M.; Bedeschi, F.; Chriss, N.; Bowers, C.; Nesti, F.

    1990-01-01

    Two types of neural network beauty trigger architectures, based on identification of electrons in jets and recognition of secondary vertices, have been simulated in the environment of the Fermilab CDF experiment. The efficiencies for B's and rejection of background obtained are encouraging. If hardware tests are successful, the electron identification architecture will be tested in the 1991 run of CDF. 10 refs., 5 figs., 1 tab

  1. Artificial neural network modelling

    CERN Document Server

    Samarasinghe, Sandhya

    2016-01-01

    This book covers theoretical aspects as well as recent innovative applications of Artificial Neural networks (ANNs) in natural, environmental, biological, social, industrial and automated systems. It presents recent results of ANNs in modelling small, large and complex systems under three categories, namely, 1) Networks, Structure Optimisation, Robustness and Stochasticity 2) Advances in Modelling Biological and Environmental Systems and 3) Advances in Modelling Social and Economic Systems. The book aims at serving undergraduates, postgraduates and researchers in ANN computational modelling. .

  2. Rotation Invariance Neural Network

    OpenAIRE

    Li, Shiyuan

    2017-01-01

    Rotation invariance and translation invariance have great values in image recognition tasks. In this paper, we bring a new architecture in convolutional neural network (CNN) named cyclic convolutional layer to achieve rotation invariance in 2-D symbol recognition. We can also get the position and orientation of the 2-D symbol by the network to achieve detection purpose for multiple non-overlap target. Last but not least, this architecture can achieve one-shot learning in some cases using thos...

  3. Neural Mechanisms of Foraging

    OpenAIRE

    Kolling, Nils; Behrens, Timothy EJ; Mars, Rogier B; Rushworth, Matthew FS

    2012-01-01

    Behavioural economic studies, involving limited numbers of choices, have provided key insights into neural decision-making mechanisms. By contrast, animals’ foraging choices arise in the context of sequences of encounters with prey/food. On each encounter the animal chooses to engage or whether the environment is sufficiently rich that searching elsewhere is merited. The cost of foraging is also critical. We demonstrate humans can alternate between two modes of choice, comparative decision-ma...

  4. Differentiation-Dependent Motility-Responses of Developing Neural Progenitors to Optogenetic Stimulation

    Directory of Open Access Journals (Sweden)

    Tímea Köhidi

    2017-12-01

    Full Text Available During neural tissue genesis, neural stem/progenitor cells are exposed to bioelectric stimuli well before synaptogenesis and neural circuit formation. Fluctuations in the electrochemical potential in the vicinity of developing cells influence the genesis, migration and maturation of neuronal precursors. The complexity of the in vivo environment and the coexistence of various progenitor populations hinder the understanding of the significance of ionic/bioelectric stimuli in the early phases of neuronal differentiation. Using optogenetic stimulation, we investigated the in vitro motility responses of radial glia-like neural stem/progenitor populations to ionic stimuli. Radial glia-like neural stem cells were isolated from CAGloxpStoploxpChR2(H134-eYFP transgenic mouse embryos. After transfection with Cre-recombinase, ChR2(channelrhodopsin-2-expressing and non-expressing cells were separated by eYFP fluorescence. Expression of light-gated ion channels were checked by patch clamp and fluorescence intensity assays. Neurogenesis by ChR2-expressing and non-expressing cells was induced by withdrawal of EGF from the medium. Cells in different (stem cell, migrating progenitor and maturing precursor stages of development were illuminated with laser light (λ = 488 nm; 1.3 mW/mm2; 300 ms in every 5 min for 12 h. The displacement of the cells was analyzed on images taken at the end of each light pulse. Results demonstrated that the migratory activity decreased with the advancement of neuronal differentiation regardless of stimulation. Light-sensitive cells, however, responded on a differentiation-dependent way. In non-differentiated ChR2-expressing stem cell populations, the motility did not change significantly in response to light-stimulation. The displacement activity of migrating progenitors was enhanced, while the motility of differentiating neuronal precursors was markedly reduced by illumination.

  5. Neural Based Orthogonal Data Fitting The EXIN Neural Networks

    CERN Document Server

    Cirrincione, Giansalvo

    2008-01-01

    Written by three leaders in the field of neural based algorithms, Neural Based Orthogonal Data Fitting proposes several neural networks, all endowed with a complete theory which not only explains their behavior, but also compares them with the existing neural and traditional algorithms. The algorithms are studied from different points of view, including: as a differential geometry problem, as a dynamic problem, as a stochastic problem, and as a numerical problem. All algorithms have also been analyzed on real time problems (large dimensional data matrices) and have shown accurate solutions. Wh

  6. Getting the word out: neural correlates of enthusiastic message propagation.

    Science.gov (United States)

    Falk, Emily B; O'Donnell, Matthew Brook; Lieberman, Matthew D

    2012-01-01

    What happens in the mind of a person who first hears a potentially exciting idea?We examined the neural precursors of spreading ideas with enthusiasm, and dissected enthusiasm into component processes that can be identified through automated linguistic analysis, gestalt human ratings of combined linguistic and non-verbal cues, and points of convergence/divergence between the two. We combined tools from natural language processing (NLP) with data gathered using fMRI to link the neurocognitive mechanisms that are set in motion during initial exposure to ideas and subsequent behaviors of these message communicators outside of the scanner. Participants' neural activity was recorded as they reviewed ideas for potential television show pilots. Participants' language from video-taped interviews collected post-scan was transcribed and given to an automated linguistic sentiment analysis (SA) classifier, which returned ratings for evaluative language (evaluative vs. descriptive) and valence (positive vs. negative). Separately, human coders rated the enthusiasm with which participants transmitted each idea. More positive sentiment ratings by the automated classifier were associated with activation in neural regions including medial prefrontal cortex; MPFC, precuneus/posterior cingulate cortex; PC/PCC, and medial temporal lobe; MTL. More evaluative, positive, descriptions were associated exclusively with neural activity in temporal-parietal junction (TPJ). Finally, human ratings indicative of more enthusiastic sentiment were associated with activation across these regions (MPFC, PC/PCC, DMPFC, TPJ, and MTL) as well as in ventral striatum (VS), inferior parietal lobule and premotor cortex. Taken together, these data demonstrate novel links between neural activity during initial idea encoding and the enthusiasm with which the ideas are subsequently delivered. This research lays the groundwork to use machine learning and neuroimaging data to study word of mouth communication and

  7. Getting the word out: Neural correlates of enthusiastic message propagation

    Directory of Open Access Journals (Sweden)

    Emily eFalk

    2012-11-01

    Full Text Available What happens in the mind of a person who first hears a potentially exciting idea? We examined the neural precursors of spreading ideas with enthusiasm, and dissect enthusiasm into component processes that can be identified through automated linguistic analysis, gestalt human ratings of combined linguistic and non-verbal cues, and points of convergence/divergence between the two. We combined tools from natural language processing with data gathered using fMRI, to link the neurocognitive mechanisms that are set in motion during initial exposure to ideas and subsequent behaviors of these message communicators outside of the scanner. Participants’ neural activity was recorded as they reviewed ideas for potential television show pilots. Participants’ language from video-taped interviews collected post-scan was transcribed and given to an automated linguistic sentiment analysis classifier, which returned ratings for evaluative language (evaluative vs. descriptive and valence (positive vs. negative. Separately, human coders rated the enthusiasm with which participants transmitted each idea. More positive sentiment ratings by the automated classifier were associated with activation in neural regions including medial prefrontal cortex; MPFC, precuneus/posterior cingulate cortex; PC/PCC, and medial temporal lobe; MTL. More evaluative, positive, descriptions were associated exclusively with neural activity in temporal parietal junction (TPJ. Finally, human ratings indicative of more enthusiastic sentiment were associated with activation across these regions (MPFC, PC/PCC, DMPFC, TPJ, MTL as well as in ventral striatum, inferior parietal lobule and premotor cortex. Taken together, these data demonstrate novel links between neural activity during initial idea encoding and the enthusiasm with which the ideas are subsequently delivered. These data also demonstrate the novel use of machine learning tools to link natural language data to neuroimaging data.

  8. Getting the word out: neural correlates of enthusiastic message propagation

    Science.gov (United States)

    Falk, Emily B.; O'Donnell, Matthew Brook; Lieberman, Matthew D.

    2012-01-01

    What happens in the mind of a person who first hears a potentially exciting idea?We examined the neural precursors of spreading ideas with enthusiasm, and dissected enthusiasm into component processes that can be identified through automated linguistic analysis, gestalt human ratings of combined linguistic and non-verbal cues, and points of convergence/divergence between the two. We combined tools from natural language processing (NLP) with data gathered using fMRI to link the neurocognitive mechanisms that are set in motion during initial exposure to ideas and subsequent behaviors of these message communicators outside of the scanner. Participants' neural activity was recorded as they reviewed ideas for potential television show pilots. Participants' language from video-taped interviews collected post-scan was transcribed and given to an automated linguistic sentiment analysis (SA) classifier, which returned ratings for evaluative language (evaluative vs. descriptive) and valence (positive vs. negative). Separately, human coders rated the enthusiasm with which participants transmitted each idea. More positive sentiment ratings by the automated classifier were associated with activation in neural regions including medial prefrontal cortex; MPFC, precuneus/posterior cingulate cortex; PC/PCC, and medial temporal lobe; MTL. More evaluative, positive, descriptions were associated exclusively with neural activity in temporal-parietal junction (TPJ). Finally, human ratings indicative of more enthusiastic sentiment were associated with activation across these regions (MPFC, PC/PCC, DMPFC, TPJ, and MTL) as well as in ventral striatum (VS), inferior parietal lobule and premotor cortex. Taken together, these data demonstrate novel links between neural activity during initial idea encoding and the enthusiasm with which the ideas are subsequently delivered. This research lays the groundwork to use machine learning and neuroimaging data to study word of mouth communication and

  9. Hydrokinetic simulations of nanoscopic precursor films in rough channels

    International Nuclear Information System (INIS)

    Chibbaro, S; Biferale, L; Binder, K; Milchev, A; Dimitrov, D; Diotallevi, F; Succi, S

    2009-01-01

    We report on simulations of capillary filling of highly wetting fluids in nanochannels with and without obstacles. We use atomistic (molecular dynamics) and hydrokinetic (lattice Boltzmann; LB) approaches which indicate clear evidence of the formation of thin precursor films, moving ahead of the main capillary front. The dynamics of the precursor films is found to obey a square-root law like that obeyed by the main capillary front, z 2 (t)∝t, although with a larger prefactor, which we find to take the same value for the different geometries (2D–3D) under inspection. The two methods show a quantitative agreement which indicates that the formation and propagation of thin precursors can be handled at a mesoscopic/hydrokinetic level. This can be considered as a validation of the LB method and opens the possibility of using hydrokinetic methods to explore space–time scales and complex geometries of direct experimental relevance. Then, the LB approach is used to study the fluid behaviour in a nanochannel when the precursor film encounters a square obstacle. A complete parametric analysis is performed which suggests that thin-film precursors may have an important influence on the efficiency of nanochannel-coating strategies

  10. Fluid Mechanics of Lean Blowout Precursors in Gas Turbine Combustors

    Directory of Open Access Journals (Sweden)

    T. M. Muruganandam

    2012-03-01

    Full Text Available Understanding of lean blowout (LBO phenomenon, along with the sensing and control strategies could enable the gas turbine combustor designers to design combustors with wider operability regimes. Sensing of precursor events (temporary extinction-reignition events based on chemiluminescence emissions from the combustor, assessing the proximity to LBO and using that data for control of LBO has already been achieved. This work describes the fluid mechanic details of the precursor dynamics and the blowout process based on detailed analysis of near blowout flame behavior, using simultaneous chemiluminescence and droplet scatter observations. The droplet scatter method represents the regions of cold reactants and thus help track unburnt mixtures. During a precursor event, it was observed that the flow pattern changes significantly with a large region of unburnt mixture in the combustor, which subsequently vanishes when a double/single helical vortex structure brings back the hot products back to the inlet of the combustor. This helical pattern is shown to be the characteristic of the next stable mode of flame in the longer combustor, stabilized by double helical vortex breakdown (VBD mode. It is proposed that random heat release fluctuations near blowout causes VBD based stabilization to shift VBD modes, causing the observed precursor dynamics in the combustor. A complete description of the evolution of flame near the blowout limit is presented. The description is consistent with all the earlier observations by the authors about precursor and blowout events.

  11. Adenine nucleotide translocator transports haem precursors into mitochondria.

    Directory of Open Access Journals (Sweden)

    Motoki Azuma

    2008-08-01

    Full Text Available Haem is a prosthetic group for haem proteins, which play an essential role in oxygen transport, respiration, signal transduction, and detoxification. In haem biosynthesis, the haem precursor protoporphyrin IX (PP IX must be accumulated into the mitochondrial matrix across the inner membrane, but its mechanism is largely unclear. Here we show that adenine nucleotide translocator (ANT, the inner membrane transporter, contributes to haem biosynthesis by facilitating mitochondrial accumulation of its precursors. We identified that haem and PP IX specifically bind to ANT. Mitochondrial uptake of PP IX was inhibited by ADP, a known substrate of ANT. Conversely, ADP uptake into mitochondria was competitively inhibited by haem and its precursors, suggesting that haem-related porphyrins are accumulated into mitochondria via ANT. Furthermore, disruption of the ANT genes in yeast resulted in a reduction of haem biosynthesis by blocking the translocation of haem precursors into the matrix. Our results represent a new model that ANT plays a crucial role in haem biosynthesis by facilitating accumulation of its precursors into the mitochondrial matrix.

  12. The stream of precursors that colonizes the thymus proceeds selectively through the early T lineage precursor stage of T cell development

    Science.gov (United States)

    Benz, Claudia; Martins, Vera C.; Radtke, Freddy; Bleul, Conrad C.

    2008-01-01

    T cell development in the thymus depends on continuous colonization by hematopoietic precursors. Several distinct T cell precursors have been identified, but whether one or several independent precursor cell types maintain thymopoiesis is unclear. We have used thymus transplantation and an inducible lineage-tracing system to identify the intrathymic precursor cells among previously described thymus-homing progenitors that give rise to the T cell lineage in the thymus. Extrathymic precursors were not investigated in these studies. Both approaches show that the stream of T cell lineage precursor cells, when entering the thymus, selectively passes through the early T lineage precursor (ETP) stage. Immigrating precursor cells do not exhibit characteristics of double-negative (DN) 1c, DN1d, or DN1e stages, or of populations containing the common lymphoid precursor 2 (CLP-2) or the thymic equivalent of circulating T cell progenitors (CTPs). It remains possible that an unknown hematopoietic precursor cell or previously described extrathymic precursors with a CLP, CLP-2, or CTP phenotype feed into T cell development by circumventing known intrathymic T cell lineage progenitor cells. However, it is clear that of the known intrathymic precursors, only the ETP population contributes significant numbers of T lineage precursors to T cell development. PMID:18458114

  13. Trimaran Resistance Artificial Neural Network

    Science.gov (United States)

    2011-01-01

    11th International Conference on Fast Sea Transportation FAST 2011, Honolulu, Hawaii, USA, September 2011 Trimaran Resistance Artificial Neural Network Richard...Trimaran Resistance Artificial Neural Network 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e... Artificial Neural Network and is restricted to the center and side-hull configurations tested. The value in the parametric model is that it is able to

  14. Brain Injury Expands the Numbers of Neural Stem Cells and Progenitors in the SVZ by Enhancing Their Responsiveness to EGF

    Directory of Open Access Journals (Sweden)

    Dhivyaa Alagappan

    2009-04-01

    Full Text Available There is an increase in the numbers of neural precursors in the SVZ (subventricular zone after moderate ischaemic injuries, but the extent of stem cell expansion and the resultant cell regeneration is modest. Therefore our studies have focused on understanding the signals that regulate these processes towards achieving a more robust amplification of the stem/progenitor cell pool. The goal of the present study was to evaluate the role of the EGFR [EGF (epidermal growth factor receptor] in the regenerative response of the neonatal SVZ to hypoxic/ischaemic injury. We show that injury recruits quiescent cells in the SVZ to proliferate, that they divide more rapidly and that there is increased EGFR expression on both putative stem cells and progenitors. With the amplification of the precursors in the SVZ after injury there is enhanced sensitivity to EGF, but not to FGF (fibroblast growth factor-2. EGF-dependent SVZ precursor expansion, as measured using the neurosphere assay, is lost when the EGFR is pharmacologically inhibited, and forced expression of a constitutively active EGFR is sufficient to recapitulate the exaggerated proliferation of the neural stem/progenitors that is induced by hypoxic/ischaemic brain injury. Cumulatively, our results reveal that increased EGFR signalling precedes that increase in the abundance of the putative neural stem cells and our studies implicate the EGFR as a key regulator of the expansion of SVZ precursors in response to brain injury. Thus modulating EGFR signalling represents a potential target for therapies to enhance brain repair from endogenous neural precursors following hypoxic/ischaemic and other brain injuries.

  15. Thin film solar cells by selenization sulfurization using diethyl selenium as a selenium precursor

    Science.gov (United States)

    Dhere, Neelkanth G.; Kadam, Ankur A.

    2009-12-15

    A method of forming a CIGSS absorber layer includes the steps of providing a metal precursor, and selenizing the metal precursor using diethyl selenium to form a selenized metal precursor layer (CIGSS absorber layer). A high efficiency solar cell includes a CIGSS absorber layer formed by a process including selenizing a metal precursor using diethyl selenium to form the CIGSS absorber layer.

  16. PARTITIONING TUNGSTEN BETWEEN MATRIX PRECURSORS AND CHONDRULE PRECURSORS THROUGH RELATIVE SETTLING

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, Alexander, E-mail: ahubbard@amnh.org [American Museum of Natural History, New York, NY (United States)

    2016-08-01

    Recent studies of chondrites have found a tungsten isotopic anomaly between chondrules and matrix. Given the refractory nature of tungsten, this implies that W was carried into the solar nebula by at least two distinct families of pre-solar grains. The observed chondrule/matrix split requires that the distinct families were kept separate during the dust coagulation process, and that the two families of grain interacted with the chondrule formation mechanism differently. We take the co-existence of different families of solids in the same general orbital region at the chondrule-precursor size as given, and explore the requirements for them to have interacted with the chondrule formation process at significantly different rates. We show that this sorting of families of solids into chondrule- and matrix-destined dust had to have been at least as powerful a sorting mechanism as the relative settling of aerodynamically distinct grains at least two scale heights above the midplane. The requirement that the chondrule formation mechanism was correlated in some fashion with a dust-grain sorting mechanism argues strongly for spatially localized chondrule formation mechanisms such as turbulent dissipation in non-thermally ionized disk surface layers, and argues against volume-filling mechanisms such as planetesimal bow shocks.

  17. PARTITIONING TUNGSTEN BETWEEN MATRIX PRECURSORS AND CHONDRULE PRECURSORS THROUGH RELATIVE SETTLING

    International Nuclear Information System (INIS)

    Hubbard, Alexander

    2016-01-01

    Recent studies of chondrites have found a tungsten isotopic anomaly between chondrules and matrix. Given the refractory nature of tungsten, this implies that W was carried into the solar nebula by at least two distinct families of pre-solar grains. The observed chondrule/matrix split requires that the distinct families were kept separate during the dust coagulation process, and that the two families of grain interacted with the chondrule formation mechanism differently. We take the co-existence of different families of solids in the same general orbital region at the chondrule-precursor size as given, and explore the requirements for them to have interacted with the chondrule formation process at significantly different rates. We show that this sorting of families of solids into chondrule- and matrix-destined dust had to have been at least as powerful a sorting mechanism as the relative settling of aerodynamically distinct grains at least two scale heights above the midplane. The requirement that the chondrule formation mechanism was correlated in some fashion with a dust-grain sorting mechanism argues strongly for spatially localized chondrule formation mechanisms such as turbulent dissipation in non-thermally ionized disk surface layers, and argues against volume-filling mechanisms such as planetesimal bow shocks.

  18. Notch signaling patterns neurogenic ectoderm and regulates the asymmetric division of neural progenitors in sea urchin embryos.

    Science.gov (United States)

    Mellott, Dan O; Thisdelle, Jordan; Burke, Robert D

    2017-10-01

    We have examined regulation of neurogenesis by Delta/Notch signaling in sea urchin embryos. At gastrulation, neural progenitors enter S phase coincident with expression of Sp-SoxC. We used a BAC containing GFP knocked into the Sp-SoxC locus to label neural progenitors. Live imaging and immunolocalizations indicate that Sp-SoxC-expressing cells divide to produce pairs of adjacent cells expressing GFP. Over an interval of about 6 h, one cell fragments, undergoes apoptosis and expresses high levels of activated Caspase3. A Notch reporter indicates that Notch signaling is activated in cells adjacent to cells expressing Sp-SoxC. Inhibition of γ-secretase, injection of Sp-Delta morpholinos or CRISPR/Cas9-induced mutation of Sp-Delta results in supernumerary neural progenitors and neurons. Interfering with Notch signaling increases neural progenitor recruitment and pairs of neural progenitors. Thus, Notch signaling restricts the number of neural progenitors recruited and regulates the fate of progeny of the asymmetric division. We propose a model in which localized signaling converts ectodermal and ciliary band cells to neural progenitors that divide asymmetrically to produce a neural precursor and an apoptotic cell. © 2017. Published by The Company of Biologists Ltd.

  19. Application of precursor methodology in initiating frequency estimates

    International Nuclear Information System (INIS)

    Kohut, P.; Fitzpatrick, R.G.

    1991-01-01

    The precursor methodology developed in recent years provides a consistent technique to identify important accident sequence precursors. It relies on operational events (extracting information from actual experience) and infers core damage scenarios based on expected safety system responses. The ranking or categorization of each precursor is determined by considering the full spectrum of potential core damage sequences. The methodology estimates the frequency of severe core damage based on the approach suggested by Apostolakis and Mosleh, which may lead to a potential overestimation of the severe-accident sequence frequency due to the inherent dependencies between the safety systems and the initiating events. The methodology is an encompassing attempt to incorporate most of the operating information available from nuclear power plants and is an attractive tool from the point of view of risk management. In this paper, a further extension of this methodology is discussed with regard to the treatment of initiating frequency of the accident sequences

  20. Early postradiation recovery of precursor cells of hemopoietic stroma

    International Nuclear Information System (INIS)

    Todriya, T.V.

    1984-01-01

    Ability of stroma precursor cells to early postradiation recovery was studied in male mices using the method of fraction irradiation of bone marrow. Donor mices of bone marrow were irradiated in vivo once by the total dose (nonfraction irradiation) and fractionally with 6 h interval between two irradiation doses. The cumulative irradiation doses equal to 10, 12, 14, 16 Gr were investigated. Irradiation was carried out using gamma facility. Bone marrow of the femur was implanted immediately after irradiation under kidney capsule of nonirradiated syngeneic recipient. The ability of stroma precursor cells to intracellular repair (repair index) was evaluated according to the ratio of the number of hemopoietic cells formed in heterotropic transplants in groups with fraction irradiation to the same one in groups with nonfraction irradiation. The obtained results testify to the fact that slowly regenerated highly radioresistant population of precursor cells of hemopoietic stroma is capable to early postradiation recovery

  1. Optics in neural computation

    Science.gov (United States)

    Levene, Michael John

    In all attempts to emulate the considerable powers of the brain, one is struck by both its immense size, parallelism, and complexity. While the fields of neural networks, artificial intelligence, and neuromorphic engineering have all attempted oversimplifications on the considerable complexity, all three can benefit from the inherent scalability and parallelism of optics. This thesis looks at specific aspects of three modes in which optics, and particularly volume holography, can play a part in neural computation. First, holography serves as the basis of highly-parallel correlators, which are the foundation of optical neural networks. The huge input capability of optical neural networks make them most useful for image processing and image recognition and tracking. These tasks benefit from the shift invariance of optical correlators. In this thesis, I analyze the capacity of correlators, and then present several techniques for controlling the amount of shift invariance. Of particular interest is the Fresnel correlator, in which the hologram is displaced from the Fourier plane. In this case, the amount of shift invariance is limited not just by the thickness of the hologram, but by the distance of the hologram from the Fourier plane. Second, volume holography can provide the huge storage capacity and high speed, parallel read-out necessary to support large artificial intelligence systems. However, previous methods for storing data in volume holograms have relied on awkward beam-steering or on as-yet non- existent cheap, wide-bandwidth, tunable laser sources. This thesis presents a new technique, shift multiplexing, which is capable of very high densities, but which has the advantage of a very simple implementation. In shift multiplexing, the reference wave consists of a focused spot a few millimeters in front of the hologram. Multiplexing is achieved by simply translating the hologram a few tens of microns or less. This thesis describes the theory for how shift

  2. A developmental perspective on the neural bases of human empathy.

    Science.gov (United States)

    Tousignant, Béatrice; Eugène, Fanny; Jackson, Philip L

    2017-08-01

    While empathy has been widely studied in philosophical and psychological literatures, recent advances in social neuroscience have shed light on the neural correlates of this complex interpersonal phenomenon. In this review, we provide an overview of brain imaging studies that have investigated the neural substrates of human empathy. Based on existing models of the functional architecture of empathy, we review evidence of the neural underpinnings of each main component, as well as their development from infancy. Although early precursors of affective sharing and self-other distinction appear to be present from birth, recent findings also suggest that even higher-order components of empathy such as perspective-taking and emotion regulation demonstrate signs of development during infancy. This merging of developmental and social neuroscience literature thus supports the view that ontogenic development of empathy is rooted in early infancy, well before the emergence of verbal abilities. With age, the refinement of top-down mechanisms may foster more appropriate empathic responses, thus promoting greater altruistic motivation and prosocial behaviors. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Bioelectrochemical control of neural cell development on conducting polymers.

    Science.gov (United States)

    Collazos-Castro, Jorge E; Polo, José L; Hernández-Labrado, Gabriel R; Padial-Cañete, Vanesa; García-Rama, Concepción

    2010-12-01

    Electrically conducting polymers hold promise for developing advanced neuroprostheses, bionic systems and neural repair devices. Among them, poly(3, 4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) exhibits superior physicochemical properties but biocompatibility issues have limited its use. We describe combinations of electrochemical and molecule self-assembling methods to consistently control neural cell development on PEDOT:PSS while maintaining very low interfacial impedance. Electro-adsorbed polylysine enabled long-term neuronal survival and growth on the nanostructured polymer. Neurite extension was strongly inhibited by an additional layer of PSS or heparin, which in turn could be either removed electrically or further coated with spermine to activate cell growth. Binding basic fibroblast growth factor (bFGF) to the heparin layer inhibited neurons but promoted proliferation and migration of precursor cells. This methodology may orchestrate neural cell behavior on electroactive polymers, thus improving cell/electrode communication in prosthetic devices and providing a platform for tissue repair strategies. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. Hemopoietic precursor cell regeneration following irradiation and syngeneic marrow transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Melchner, H. von

    1983-01-01

    The transplantation of hemopoietic cells into adequately pretreated recipients represents one of the most promising approaches in the treatment of immunohematological disorders such as aplastic anemia, immunodeficiency diseases, leukemias and malignant lymphomas. The basic property of the hemopoietic cells permitting such therapeutic procedure, namely, the capacity of hemopoietic precursors to actively proliferate and differentiate in recipients suffering the consequences of various kinds of hemopoietic failure, represents the subject of the present review. The main cell populations addressed in the subsequent sections are the hemopoietic precursor cells. Mature end cells and in particular lymphocytes did not receive as much attention.

  5. IL-9-Producing Mast Cell Precursors and Food Allergy

    Science.gov (United States)

    2017-10-01

    AWARD NUMBER: W81XWH-15-1-0517 TITLE: IL-9-Producing Mast Cell Precursors and Food Allergy PRINCIPAL INVESTIGATOR: Dr. Simon P. Hogan PhD...IL-9-Producing Mast Cell Precursors and Food Allergy 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Yui Hsi Wang, Sunil...threatening anaphylaxis. We have identified a novel multi-functional IL-9-producing mucosal mast cells (MMC9s) that produce large amounts of IL-9, IL

  6. Do glycine-extended hormone precursors have clinical significance?

    DEFF Research Database (Denmark)

    Rehfeld, Jens Frederik

    2014-01-01

    Half of the known peptide hormones are C-terminally amidated. Subsequent biogenesis studies have shown that the immediate precursor is a glycine-extended peptide. The clinical interest in glycine-extended hormones began in 1994, when it was suggested that glycine-extended gastrin stimulated cancer...... and clinical effects of glycine-extended precursors for most other amidated hormones than gastrin and cholecystokinin (CCK). The idea of glycine-extended peptides as independent messengers was interesting. But clinical science has to move ahead from ideas that cannot be supported at key points after decades...

  7. Differentiation of Mouse Embryonic Stem Cells into Ventral Foregut Precursors

    DEFF Research Database (Denmark)

    Rothová, Michaela; Hölzenspies, Jurriaan J; Livigni, Alessandra

    2016-01-01

    Anterior definitive endoderm (ADE), the ventral foregut precursor, is both an important embryonic signaling center and a unique multipotent precursor of liver, pancreas, and other organs. Here, a method is described for the differentiation of mouse embryonic stem cells (mESCs) to definitive...... endoderm with pronounced anterior character. ADE-containing cultures can be produced in vitro by suspension (embryoid body) culture or in a serum-free adherent monolayer culture. ESC-derived ADE cells are committed to endodermal fates and can undergo further differentiation in vitro towards ventral foregut...

  8. Analysis of neural networks

    CERN Document Server

    Heiden, Uwe

    1980-01-01

    The purpose of this work is a unified and general treatment of activity in neural networks from a mathematical pOint of view. Possible applications of the theory presented are indica­ ted throughout the text. However, they are not explored in de­ tail for two reasons : first, the universal character of n- ral activity in nearly all animals requires some type of a general approach~ secondly, the mathematical perspicuity would suffer if too many experimental details and empirical peculiarities were interspersed among the mathematical investigation. A guide to many applications is supplied by the references concerning a variety of specific issues. Of course the theory does not aim at covering all individual problems. Moreover there are other approaches to neural network theory (see e.g. Poggio-Torre, 1978) based on the different lev­ els at which the nervous system may be viewed. The theory is a deterministic one reflecting the average be­ havior of neurons or neuron pools. In this respect the essay is writt...

  9. Neural Synchronization and Cryptography

    Science.gov (United States)

    Ruttor, Andreas

    2007-11-01

    Neural networks can synchronize by learning from each other. In the case of discrete weights full synchronization is achieved in a finite number of steps. Additional networks can be trained by using the inputs and outputs generated during this process as examples. Several learning rules for both tasks are presented and analyzed. In the case of Tree Parity Machines synchronization is much faster than learning. Scaling laws for the number of steps needed for full synchronization and successful learning are derived using analytical models. They indicate that the difference between both processes can be controlled by changing the synaptic depth. In the case of bidirectional interaction the synchronization time increases proportional to the square of this parameter, but it grows exponentially, if information is transmitted in one direction only. Because of this effect neural synchronization can be used to construct a cryptographic key-exchange protocol. Here the partners benefit from mutual interaction, so that a passive attacker is usually unable to learn the generated key in time. The success probabilities of different attack methods are determined by numerical simulations and scaling laws are derived from the data. They show that the partners can reach any desired level of security by just increasing the synaptic depth. Then the complexity of a successful attack grows exponentially, but there is only a polynomial increase of the effort needed to generate a key. Further improvements of security are possible by replacing the random inputs with queries generated by the partners.

  10. Neural Networks for Optimal Control

    DEFF Research Database (Denmark)

    Sørensen, O.

    1995-01-01

    Two neural networks are trained to act as an observer and a controller, respectively, to control a non-linear, multi-variable process.......Two neural networks are trained to act as an observer and a controller, respectively, to control a non-linear, multi-variable process....

  11. Neural networks at the Tevatron

    International Nuclear Information System (INIS)

    Badgett, W.; Burkett, K.; Campbell, M.K.; Wu, D.Y.; Bianchin, S.; DeNardi, M.; Pauletta, G.; Santi, L.; Caner, A.; Denby, B.; Haggerty, H.; Lindsey, C.S.; Wainer, N.; Dall'Agata, M.; Johns, K.; Dickson, M.; Stanco, L.; Wyss, J.L.

    1992-10-01

    This paper summarizes neural network applications at the Fermilab Tevatron, including the first online hardware application in high energy physics (muon tracking): the CDF and DO neural network triggers; offline quark/gluon discrimination at CDF; ND a new tool for top to multijets recognition at CDF

  12. Neural Networks for the Beginner.

    Science.gov (United States)

    Snyder, Robin M.

    Motivated by the brain, neural networks are a right-brained approach to artificial intelligence that is used to recognize patterns based on previous training. In practice, one would not program an expert system to recognize a pattern and one would not train a neural network to make decisions from rules; but one could combine the best features of…

  13. Neural fields theory and applications

    CERN Document Server

    Graben, Peter; Potthast, Roland; Wright, James

    2014-01-01

    With this book, the editors present the first comprehensive collection in neural field studies, authored by leading scientists in the field - among them are two of the founding-fathers of neural field theory. Up to now, research results in the field have been disseminated across a number of distinct journals from mathematics, computational neuroscience, biophysics, cognitive science and others. Starting with a tutorial for novices in neural field studies, the book comprises chapters on emergent patterns, their phase transitions and evolution, on stochastic approaches, cortical development, cognition, robotics and computation, large-scale numerical simulations, the coupling of neural fields to the electroencephalogram and phase transitions in anesthesia. The intended readership are students and scientists in applied mathematics, theoretical physics, theoretical biology, and computational neuroscience. Neural field theory and its applications have a long-standing tradition in the mathematical and computational ...

  14. Artificial neural networks in NDT

    International Nuclear Information System (INIS)

    Abdul Aziz Mohamed

    2001-01-01

    Artificial neural networks, simply known as neural networks, have attracted considerable interest in recent years largely because of a growing recognition of the potential of these computational paradigms as powerful alternative models to conventional pattern recognition or function approximation techniques. The neural networks approach is having a profound effect on almost all fields, and has been utilised in fields Where experimental inter-disciplinary work is being carried out. Being a multidisciplinary subject with a broad knowledge base, Nondestructive Testing (NDT) or Nondestructive Evaluation (NDE) is no exception. This paper explains typical applications of neural networks in NDT/NDE. Three promising types of neural networks are highlighted, namely, back-propagation, binary Hopfield and Kohonen's self-organising maps. (Author)

  15. Developmental Dyslexia: Early Precursors, Neurobehavioral Markers, and Biological Substrates

    Science.gov (United States)

    Benasich, April A., Ed.; Fitch, R. Holly, Ed.

    2012-01-01

    Understanding the precursors and early indicators of dyslexia is key to early identification and effective intervention. Now there's a single research volume that brings together the very latest knowledge on the earliest stages of dyslexia and the diverse genetic, neurobiological, and cognitive factors that may contribute to it. Based on findings…

  16. Manganite perovskite ceramics, their precursors and methods for forming

    Science.gov (United States)

    Payne, David Alan; Clothier, Brent Allen

    2015-03-10

    Disclosed are a variety of ceramics having the formula Ln.sub.1-xM.sub.xMnO.sub.3, where 0.Itoreq.x.Itoreq.1 and where Ln is La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu or Y; M is Ca, Sr, Ba, Cd, or Pb; manganite precursors for preparing the ceramics; a method for preparing the precursors; and a method for transforming the precursors into uniform, defect-free ceramics having magnetoresistance properties. The manganite precursors contain a sol and are derived from the metal alkoxides: Ln(OR).sub.3, M(OR).sub.2 and Mn(OR).sub.2, where R is C.sub.2 to C.sub.6 alkyl or C.sub.3 to C.sub.9 alkoxyalkyl, or C.sub.6 to C.sub.9 aryl. The preferred ceramics are films prepared by a spin coating method and are particularly suited for incorporation into a device such as an integrated circuit device.

  17. Development of precursors recognition methods in vector signals

    Science.gov (United States)

    Kapralov, V. G.; Elagin, V. V.; Kaveeva, E. G.; Stankevich, L. A.; Dremin, M. M.; Krylov, S. V.; Borovov, A. E.; Harfush, H. A.; Sedov, K. S.

    2017-10-01

    Precursor recognition methods in vector signals of plasma diagnostics are presented. Their requirements and possible options for their development are considered. In particular, the variants of using symbolic regression for building a plasma disruption prediction system are discussed. The initial data preparation using correlation analysis and symbolic regression is discussed. Special attention is paid to the possibility of using algorithms in real time.

  18. High regioselective acetylation of vitamin A precursors using lipase ...

    African Journals Online (AJOL)

    Administrator

    2011-09-26

    Sep 26, 2011 ... High regioselective acetylation of vitamin A precursors using lipase B from Candida antarctica in organic media. Jingpeng Sun, Keju Jing* and Yinghua Lu. Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen. University, Xiamen 361005, P. R. ...

  19. Technical Note: Methionine, a precursor of methane in living plants

    Science.gov (United States)

    Lenhart, K.; Althoff, F.; Greule, M.; Keppler, F.

    2015-03-01

    When terrestrial plants were identified as producers of the greenhouse gas methane, much discussion and debate ensued not only about their contribution to the global methane budget but also with regard to the validity of the observation itself. Although the phenomenon has now become more accepted for both living and dead plants, the mechanism of methane formation in living plants remains to be elucidated and its precursor compounds to be identified. We made use of stable isotope techniques to verify the in vivo formation of methane, and, in order to identify the carbon precursor, 13C positionally labeled organic compounds were employed. Here we show that the amino acid L-methionine acts as a methane precursor in living plants. Employing 13C-labeled methionine clearly identified the sulfur-bound methyl group of methionine as a carbon precursor of methane released from lavender (Lavandula angustifolia). Furthermore, when lavender plants were stressed physically, methane release rates and the stable carbon isotope values of the emitted methane greatly increased. Our results provide additional support that plants possess a mechanism for methane production and suggest that methionine might play an important role in the formation of methane in living plants, particularly under stress conditions.

  20. Process for producing ceramic nitrides anc carbonitrides and their precursors

    Science.gov (United States)

    Brown, G.M.; Maya, L.

    1987-02-25

    A process for preparing ceramic nitrides and carbon nitrides in the form of very pure, fine particulate powder. Appropriate precursors is prepared by reaching a transition metal alkylamide with ammonia to produce a mixture of metal amide and metal imide in the form of an easily pyrolyzable precipitate.

  1. Boron nitride ceramics from molecular precursors: synthesis, properties and applications.

    Science.gov (United States)

    Bernard, Samuel; Salameh, Chrystelle; Miele, Philippe

    2016-01-21

    Hexagonal boron nitride (h-BN) attracts considerable interest because its structure is similar to that of carbon graphite while it displays different properties which are of interest for environmental and green technologies. The polar nature of the B-N bond in sp(2)-bonded BN makes it a wide band gap insulator with different chemistry on its surface and particular physical and chemical properties such as a high thermal conductivity, a high temperature stability, a high resistance to corrosion and oxidation and a strong UV emission. It is chemically inert and nontoxic and has good environmental compatibility. h-BN also has enhanced physisorption properties due to the dipolar fields near its surface. Such properties are closely dependent on the processing method. Bottom-up approaches consist of transforming molecular precursors into non-oxide ceramics with retention of the structural units inherent to the precursor molecule. The purpose of the present review is to give an up-to-date overview on the most recent achievements in the preparation of h-BN from borazine-based molecular single-source precursors including borazine and 2,4,6-trichloroborazine through both vapor phase syntheses and methods in the liquid/solid state involving polymeric intermediates, called the Polymer-Derived Ceramics (PDCs) route. In particular, the effect of the chemistry, composition and architecture of the borazine-based precursors and derived polymers on the shaping ability as well as the properties of h-BN is particularly highlighted.

  2. Multiple Modes of Communication between Neurons and Oligodendrocyte Precursor Cells

    NARCIS (Netherlands)

    Maldonado, Paloma P; Angulo, María Cecilia

    The surprising discovery of bona fide synapses between neurons and oligodendrocytes precursor cells (OPCs) 15 years ago placed these progenitors as real partners of neurons in the CNS. The role of these synapses has not been established yet, but a main hypothesis is that neuron-OPC synaptic activity

  3. Methionine as a Precursor of Ethylene—Commentary

    Science.gov (United States)

    Lieberman et al. showed in a 1966 publication of Plant Physiology that methionine is a precursor of ethylene. It was the first paper that showed ethylene carbons are derived from carbons 3 and 4 of methionine. This paper catalyzed remarkable interest among plant biologists to elucidate the biosynth...

  4. Carbon molecular sieve membranes prepared from porous fiber precursor

    NARCIS (Netherlands)

    Barsema, J.N.; van der Vegt, N.F.A.; Koops, G.H.; Wessling, Matthias

    2002-01-01

    Carbon molecular sieve (CMS) membranes are usually prepared from dense polymeric precursors that already show intrinsic gas separation properties. The rationale behind this approach is that the occurrence of any kind of initial porosity will deteriorate the final CMS performance. We will show that

  5. Polyazidopyrimidines: High Energy Compounds and Precursors to Carbon Nanotubes (Postprint)

    National Research Council Canada - National Science Library

    Ye, Chengfeng; Gao, Haixiang; Boatz, Jerry A; Drake, Gregory W; Twamley, Brendan; Shreeve, Jean'ne M

    2006-01-01

    ...). The compound 4,4',6,6'-tetra(azido)azo-1,3,5-triazine (2), has a heat of formation of 2171 (6164 kJ kg -1) (Fig. 1). Recently it was demonstrated that 1 and 2 were good precursors to nano carbon nitride materials...

  6. NdRhSn: A ferromagnet with an antiferromagnetic precursor

    Czech Academy of Sciences Publication Activity Database

    Mihalik, M.; Prokleška, J.; Kamarád, Jiří; Prokeš, K.; Isnard, O.; McIntyre, G. J.; Dönni, A.; Yoshii, S.; Kitazawa, H.; Sechovský, V.; de Boer, F.R.

    2011-01-01

    Roč. 83, č. 10 (2011), "104403-1"-"104403-10" ISSN 1098-0121 R&D Projects: GA ČR GA202/09/1027 Institutional research plan: CEZ:AV0Z10100521 Keywords : NdRhSn * ferromagnet * antiferromagnetic precursor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.691, year: 2011

  7. Electrical properties of a novel lead alkoxide precursor: Lead glycolate

    International Nuclear Information System (INIS)

    Tangboriboon, Nuchnapa; Pakdeewanishsukho, Kittikhun; Jamieson, Alexander; Sirivat, Anuvat; Wongkasemjit, Sujitra

    2006-01-01

    The reaction of lead acetate trihydrate Pb(CH 3 COO) 2 .3H 2 O and ethylene glycol, using triethylenetetramine (TETA) as a catalyst, provides in one step access to a polymer-like precursor of lead glycolate [-PbOCH 2 CH 2 O-]. On the basis of high-resolution mass spectroscopy, chemical analysis composition, FTIR, 13 C-solid state NMR and TGA, the lead glycolate precursor can be identified as a trimer structure. The FTIR spectrum demonstrates the characteristics of lead glycolate; the peaks at 1086 and 1042 cm -1 can be assigned to the C-O-Pb stretchings. The 13 C-solid state NMR spectrum gives notably only one peak at 68.639 ppm belonging to the ethylene glycol ligand. The phase transformations of lead glycolate and lead acetate trihydrate to lead oxide, their microstructures, and electrical properties were found to vary with increasing temperature. The lead glycolate precursor has superior electrical properties relative to those of lead acetate trihydrate, suggesting that the lead glycolate precursor can possibly be used as a starting material for producing electrical and semiconducting ceramics, viz. ferroelectric, anti-ferroelectric, and piezoelectric materials

  8. Deposition on disordered substrates with precursor layer diffusion

    Science.gov (United States)

    Filipe, J. A. N.; Rodgers, G. J.; Tavassoli, Z.

    1998-09-01

    Recently we introduced a one-dimensional accelerated random sequential adsorption process as a model for chemisorption with precursor layer diffusion. In this paper we consider this deposition process on disordered or impure substrates. The problem is solved exactly on both the lattice and continuum and for various impurity distributions. The results are compared with those from the standard random sequential adsorption model.

  9. College Student Stress: A Predictor of Eating Disorder Precursor Behaviors

    Science.gov (United States)

    Shelton, Virginia L.; Valkyrie, Karena T.

    2010-01-01

    Eating disorders are compulsive behaviors that can consume a person's life to the point of becoming life threatening. Previous research found stress associated with eating disorders. College can be a stressful time. If stress predicted precursor behaviors to eating disorders, then counselors would have a better chance to help students sooner. This…

  10. Low temperature catalyst-assisted pyrolysis of polymer precursors to ...

    Indian Academy of Sciences (India)

    2017-11-15

    Nov 15, 2017 ... convert the organic compounds into high-performance car- bon. PAN is one of the ... yield, RF organic gel is also identified as a widely used precursor to produce ..... sis were applied to estimate radius of gyration (Rg) and surface ... pyrolysis approach without compromising the yield and qual- ity of the final ...

  11. Xylopia Aethiopica lowers Plasma Lipid Precursors of Reproductive ...

    African Journals Online (AJOL)

    Xylopia Aethiopica lowers Plasma Lipid Precursors of Reproductive Hormones in Wister Rats. PC Onyebuagu, CP Aloamaka, JC Igweh. Abstract. This study investigated the effects of dietary Xylopia aethiopica on reproductive hormones and plasma lipids in rats. 10 male and 10 female Wistar rats weighing 200-220g and ...

  12. Solution precursor plasma deposition of nanostructured ZnO coatings

    International Nuclear Information System (INIS)

    Tummala, Raghavender; Guduru, Ramesh K.; Mohanty, Pravansu S.

    2011-01-01

    Highlights: → The solution precursor route employed is an inexpensive process with capability to produce large scale coatings at fast rates on mass scale production. → It is highly capable of developing tailorable nanostructures. → This technique can be employed to spray the coatings on any kind of substrates including polymers. → The ZnO coatings developed via solution precursor plasma spray process have good electrical conductivity and reflectivity properties in spite of possessing large amount of particulate boundaries, porosity and nanostructured grains. -- Abstract: Zinc oxide (ZnO) is a wide band gap semiconducting material that has various applications including optical, electronic, biomedical and corrosion protection. It is usually synthesized via processing routes, such as vapor deposition techniques, sol-gel, spray pyrolysis and thermal spray of pre-synthesized ZnO powders. Cheaper and faster synthesis techniques are of technological importance due to increased demand in alternative energy applications. Here, we report synthesis of nanostructured ZnO coatings directly from a solution precursor in a single step using plasma spray technique. Nanostructured ZnO coatings were deposited from the solution precursor prepared using zinc acetate and water/isopropanol. An axial liquid atomizer was employed in a DC plasma spray torch to create fine droplets of precursor for faster thermal treatment in the plasma plume to form ZnO. Microstructures of coatings revealed ultrafine particulate agglomerates. X-ray diffraction confirmed polycrystalline nature and hexagonal Wurtzite crystal structure of the coatings. Transmission electron microscopy studies showed fine grains in the range of 10-40 nm. Observed optical transmittance (∼65-80%) and reflectivity (∼65-70%) in the visible spectrum, and electrical resistivity (48.5-50.1 mΩ cm) of ZnO coatings are attributed to ultrafine particulate morphology of the coatings.

  13. Solution precursor plasma deposition of nanostructured ZnO coatings

    Energy Technology Data Exchange (ETDEWEB)

    Tummala, Raghavender [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States); Guduru, Ramesh K., E-mail: rkguduru@umich.edu [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States); Mohanty, Pravansu S. [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States)

    2011-08-15

    Highlights: {yields} The solution precursor route employed is an inexpensive process with capability to produce large scale coatings at fast rates on mass scale production. {yields} It is highly capable of developing tailorable nanostructures. {yields} This technique can be employed to spray the coatings on any kind of substrates including polymers. {yields} The ZnO coatings developed via solution precursor plasma spray process have good electrical conductivity and reflectivity properties in spite of possessing large amount of particulate boundaries, porosity and nanostructured grains. -- Abstract: Zinc oxide (ZnO) is a wide band gap semiconducting material that has various applications including optical, electronic, biomedical and corrosion protection. It is usually synthesized via processing routes, such as vapor deposition techniques, sol-gel, spray pyrolysis and thermal spray of pre-synthesized ZnO powders. Cheaper and faster synthesis techniques are of technological importance due to increased demand in alternative energy applications. Here, we report synthesis of nanostructured ZnO coatings directly from a solution precursor in a single step using plasma spray technique. Nanostructured ZnO coatings were deposited from the solution precursor prepared using zinc acetate and water/isopropanol. An axial liquid atomizer was employed in a DC plasma spray torch to create fine droplets of precursor for faster thermal treatment in the plasma plume to form ZnO. Microstructures of coatings revealed ultrafine particulate agglomerates. X-ray diffraction confirmed polycrystalline nature and hexagonal Wurtzite crystal structure of the coatings. Transmission electron microscopy studies showed fine grains in the range of 10-40 nm. Observed optical transmittance ({approx}65-80%) and reflectivity ({approx}65-70%) in the visible spectrum, and electrical resistivity (48.5-50.1 m{Omega} cm) of ZnO coatings are attributed to ultrafine particulate morphology of the coatings.

  14. The operational cloud retrieval algorithms from TROPOMI on board Sentinel-5 Precursor

    Science.gov (United States)

    Loyola, Diego G.; Gimeno García, Sebastián; Lutz, Ronny; Argyrouli, Athina; Romahn, Fabian; Spurr, Robert J. D.; Pedergnana, Mattia; Doicu, Adrian; Molina García, Víctor; Schüssler, Olena

    2018-01-01

    This paper presents the operational cloud retrieval algorithms for the TROPOspheric Monitoring Instrument (TROPOMI) on board the European Space Agency Sentinel-5 Precursor (S5P) mission scheduled for launch in 2017. Two algorithms working in tandem are used for retrieving cloud properties: OCRA (Optical Cloud Recognition Algorithm) and ROCINN (Retrieval of Cloud Information using Neural Networks). OCRA retrieves the cloud fraction using TROPOMI measurements in the ultraviolet (UV) and visible (VIS) spectral regions, and ROCINN retrieves the cloud top height (pressure) and optical thickness (albedo) using TROPOMI measurements in and around the oxygen A-band in the near infrared (NIR). Cloud parameters from TROPOMI/S5P will be used not only for enhancing the accuracy of trace gas retrievals but also for extending the satellite data record of cloud information derived from oxygen A-band measurements, a record initiated with the Global Ozone Monitoring Experiment (GOME) on board the second European Remote-Sensing Satellite (ERS-2) over 20 years ago. The OCRA and ROCINN algorithms are integrated in the S5P operational processor UPAS (Universal Processor for UV/VIS/NIR Atmospheric Spectrometers), and we present here UPAS cloud results using the Ozone Monitoring Instrument (OMI) and GOME-2 measurements. In addition, we examine anticipated challenges for the TROPOMI/S5P cloud retrieval algorithms, and we discuss the future validation needs for OCRA and ROCINN.

  15. The operational cloud retrieval algorithms from TROPOMI on board Sentinel-5 Precursor

    Directory of Open Access Journals (Sweden)

    D. G. Loyola

    2018-01-01

    Full Text Available This paper presents the operational cloud retrieval algorithms for the TROPOspheric Monitoring Instrument (TROPOMI on board the European Space Agency Sentinel-5 Precursor (S5P mission scheduled for launch in 2017. Two algorithms working in tandem are used for retrieving cloud properties: OCRA (Optical Cloud Recognition Algorithm and ROCINN (Retrieval of Cloud Information using Neural Networks. OCRA retrieves the cloud fraction using TROPOMI measurements in the ultraviolet (UV and visible (VIS spectral regions, and ROCINN retrieves the cloud top height (pressure and optical thickness (albedo using TROPOMI measurements in and around the oxygen A-band in the near infrared (NIR. Cloud parameters from TROPOMI/S5P will be used not only for enhancing the accuracy of trace gas retrievals but also for extending the satellite data record of cloud information derived from oxygen A-band measurements, a record initiated with the Global Ozone Monitoring Experiment (GOME on board the second European Remote-Sensing Satellite (ERS-2 over 20 years ago. The OCRA and ROCINN algorithms are integrated in the S5P operational processor UPAS (Universal Processor for UV/VIS/NIR Atmospheric Spectrometers, and we present here UPAS cloud results using the Ozone Monitoring Instrument (OMI and GOME-2 measurements. In addition, we examine anticipated challenges for the TROPOMI/S5P cloud retrieval algorithms, and we discuss the future validation needs for OCRA and ROCINN.

  16. The functional performance of microencapsulated human pancreatic islet-derived precursor cells.

    Science.gov (United States)

    Montanucci, Pia; Pennoni, Ilaria; Pescara, Teresa; Blasi, Paolo; Bistoni, Giovanni; Basta, Giuseppe; Calafiore, Riccardo

    2011-12-01

    We have examined long-term cultured, human islet-derived stem/precursor cells (hIPC). Whole human islets (HI) were obtained by multi-enzymatic digestion of cadaveric donor pancreases, plated on tissue flasks, and allowed to adhere and expand for several in vitro passages, in order to obtain hIPC. We detected specific stem cell markers (Oct-4, Sox-2, Nanog, ABCG2, Klf-4, CD117) in both intact HI and hIPC. Moreover, hIPC while retaining the expression of Glut-2, Pdx-1, CK-19, and ICA-512, started re-expressing Ngn3, thereby indicating acquisition of a specific pancreatic islet beta cell-oriented phenotype identity. The intrinsic plasticity of hIPC was documented by their ability to differentiate into various germ layer-derived cell phenotypes (ie, osteocytic, adipocytic and neural), including endocrine cells associated with insulin secretory capacity. To render hIPC suitable for transplantation we have enveloped them within our highly purified, alginate-based microcapsules. Upon intraperitoneal graft in NOD/SCID mice we have observed that the microcapsules acted as three-dimensional niches favouring post-transplant hIPC differentiation and acquisition of beta cell-like functional competence. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Cannabidiol Activates Neuronal Precursor Genes in Human Gingival Mesenchymal Stromal Cells.

    Science.gov (United States)

    Soundara Rajan, Thangavelu; Giacoppo, Sabrina; Scionti, Domenico; Diomede, Francesca; Grassi, Gianpaolo; Pollastro, Federica; Piattelli, Adriano; Bramanti, Placido; Mazzon, Emanuela; Trubiani, Oriana

    2017-06-01

    In the last years, mesenchymal stromal cells (MSCs) from oral tissues have received considerable interest in regenerative medicine since they can be obtained with minimal invasive procedure and exhibit immunomodulatory properties. This study was aimed to investigate whether in vitro pre-treatment of MSCs obtained from human gingiva (hGMSCs) with Cannabidiol (CBD), a cannabinoid component produced by the plant Cannabis sativa, may promote human gingiva derived MSCs to differentiate toward neuronal precursor cells. Specifically, we have treated the hGMSCs with CBD (5 µM) for 24 h in order to evaluate the expression of genes involved in cannabidiol signaling, cell proliferation, self-renewal and multipotency, and neural progenitor cells differentiation. Next generation sequencing (NGS) demonstrated that CBD activates genes associated with G protein coupled receptor signaling in hGMSCs. Genes involved in DNA replication, cell cycle, proliferation, and apoptosis were regulated. Moreover, genes associated with the biological process of neuronal progenitor cells (NCPs) proliferation, neuron differentiation, neurogenesis, and nervous system development were significantly modulated. From our results, we hypothesize that human gingiva-derived MSCs conditioned with CBD could represent a valid method for improving the hGMSCs phenotype and thus might be a potential therapeutic tool in the treatment of neurodegenerative diseases. J. Cell. Biochem. 118: 1531-1546, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  18. Interacting neural networks

    Science.gov (United States)

    Metzler, R.; Kinzel, W.; Kanter, I.

    2000-08-01

    Several scenarios of interacting neural networks which are trained either in an identical or in a competitive way are solved analytically. In the case of identical training each perceptron receives the output of its neighbor. The symmetry of the stationary state as well as the sensitivity to the used training algorithm are investigated. Two competitive perceptrons trained on mutually exclusive learning aims and a perceptron which is trained on the opposite of its own output are examined analytically. An ensemble of competitive perceptrons is used as decision-making algorithms in a model of a closed market (El Farol Bar problem or the Minority Game. In this game, a set of agents who have to make a binary decision is considered.); each network is trained on the history of minority decisions. This ensemble of perceptrons relaxes to a stationary state whose performance can be better than random.

  19. Neural circuitry and immunity

    Science.gov (United States)

    Pavlov, Valentin A.; Tracey, Kevin J.

    2015-01-01

    Research during the last decade has significantly advanced our understanding of the molecular mechanisms at the interface between the nervous system and the immune system. Insight into bidirectional neuroimmune communication has characterized the nervous system as an important partner of the immune system in the regulation of inflammation. Neuronal pathways, including the vagus nerve-based inflammatory reflex are physiological regulators of immune function and inflammation. In parallel, neuronal function is altered in conditions characterized by immune dysregulation and inflammation. Here, we review these regulatory mechanisms and describe the neural circuitry modulating immunity. Understanding these mechanisms reveals possibilities to use targeted neuromodulation as a therapeutic approach for inflammatory and autoimmune disorders. These findings and current clinical exploration of neuromodulation in the treatment of inflammatory diseases defines the emerging field of Bioelectronic Medicine. PMID:26512000

  20. Neural Darwinism and consciousness.

    Science.gov (United States)

    Seth, Anil K; Baars, Bernard J

    2005-03-01

    Neural Darwinism (ND) is a large scale selectionist theory of brain development and function that has been hypothesized to relate to consciousness. According to ND, consciousness is entailed by reentrant interactions among neuronal populations in the thalamocortical system (the 'dynamic core'). These interactions, which permit high-order discriminations among possible core states, confer selective advantages on organisms possessing them by linking current perceptual events to a past history of value-dependent learning. Here, we assess the consistency of ND with 16 widely recognized properties of consciousness, both physiological (for example, consciousness is associated with widespread, relatively fast, low amplitude interactions in the thalamocortical system), and phenomenal (for example, consciousness involves the existence of a private flow of events available only to the experiencing subject). While no theory accounts fully for all of these properties at present, we find that ND and its recent extensions fare well.

  1. Twist1 Controls a Cell-Specification Switch Governing Cell Fate Decisions within the Cardiac Neural Crest

    Science.gov (United States)

    Vincentz, Joshua W.; Firulli, Beth A.; Lin, Andrea; Spicer, Douglas B.; Howard, Marthe J.; Firulli, Anthony B.

    2013-01-01

    Neural crest cells are multipotent progenitor cells that can generate both ectodermal cell types, such as neurons, and mesodermal cell types, such as smooth muscle. The mechanisms controlling this cell fate choice are not known. The basic Helix-loop-Helix (bHLH) transcription factor Twist1 is expressed throughout the migratory and post-migratory cardiac neural crest. Twist1 ablation or mutation of the Twist-box causes differentiation of ectopic neuronal cells, which molecularly resemble sympathetic ganglia, in the cardiac outflow tract. Twist1 interacts with the pro-neural factor Sox10 via its Twist-box domain and binds to the Phox2b promoter to repress transcriptional activity. Mesodermal cardiac neural crest trans-differentiation into ectodermal sympathetic ganglia-like neurons is dependent upon Phox2b function. Ectopic Twist1 expression in neural crest precursors disrupts sympathetic neurogenesis. These data demonstrate that Twist1 functions in post-migratory neural crest cells to repress pro-neural factors and thereby regulate cell fate determination between ectodermal and mesodermal lineages. PMID:23555309

  2. Neural Crest-Derived Mesenchymal Cells Require Wnt Signaling for Their Development and Drive Invagination of the Telencephalic Midline

    Science.gov (United States)

    Choe, Youngshik; Zarbalis, Konstantinos S.; Pleasure, Samuel J.

    2014-01-01

    Embryonic neural crest cells contribute to the development of the craniofacial mesenchyme, forebrain meninges and perivascular cells. In this study, we investigated the function of ß-catenin signaling in neural crest cells abutting the dorsal forebrain during development. In the absence of ß-catenin signaling, neural crest cells failed to expand in the interhemispheric region and produced ectopic smooth muscle cells instead of generating dermal and calvarial mesenchyme. In contrast, constitutive expression of stabilized ß-catenin in neural crest cells increased the number of mesenchymal lineage precursors suggesting that ß-catenin signaling is necessary for the expansion of neural crest-derived mesenchymal cells. Interestingly, the loss of neural crest-derived mesenchymal stem cells (MSCs) leads to failure of telencephalic midline invagination and causes ventricular system defects. This study shows that ß-catenin signaling is required for the switch of neural crest cells to MSCs and mediates the expansion of MSCs to drive the formation of mesenchymal structures of the head. Furthermore, loss of these structures causes striking defects in forebrain morphogenesis. PMID:24516524

  3. Neural crest-derived mesenchymal cells require Wnt signaling for their development and drive invagination of the telencephalic midline.

    Directory of Open Access Journals (Sweden)

    Youngshik Choe

    Full Text Available Embryonic neural crest cells contribute to the development of the craniofacial mesenchyme, forebrain meninges and perivascular cells. In this study, we investigated the function of ß-catenin signaling in neural crest cells abutting the dorsal forebrain during development. In the absence of ß-catenin signaling, neural crest cells failed to expand in the interhemispheric region and produced ectopic smooth muscle cells instead of generating dermal and calvarial mesenchyme. In contrast, constitutive expression of stabilized ß-catenin in neural crest cells increased the number of mesenchymal lineage precursors suggesting that ß-catenin signaling is necessary for the expansion of neural crest-derived mesenchymal cells. Interestingly, the loss of neural crest-derived mesenchymal stem cells (MSCs leads to failure of telencephalic midline invagination and causes ventricular system defects. This study shows that ß-catenin signaling is required for the switch of neural crest cells to MSCs and mediates the expansion of MSCs to drive the formation of mesenchymal structures of the head. Furthermore, loss of these structures causes striking defects in forebrain morphogenesis.

  4. Program Helps Simulate Neural Networks

    Science.gov (United States)

    Villarreal, James; Mcintire, Gary

    1993-01-01

    Neural Network Environment on Transputer System (NNETS) computer program provides users high degree of flexibility in creating and manipulating wide variety of neural-network topologies at processing speeds not found in conventional computing environments. Supports back-propagation and back-propagation-related algorithms. Back-propagation algorithm used is implementation of Rumelhart's generalized delta rule. NNETS developed on INMOS Transputer(R). Predefines back-propagation network, Jordan network, and reinforcement network to assist users in learning and defining own networks. Also enables users to configure other neural-network paradigms from NNETS basic architecture. Small portion of software written in OCCAM(R) language.

  5. Artificial Neural Network Analysis System

    Science.gov (United States)

    2001-02-27

    Contract No. DASG60-00-M-0201 Purchase request no.: Foot in the Door-01 Title Name: Artificial Neural Network Analysis System Company: Atlantic... Artificial Neural Network Analysis System 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Powell, Bruce C 5d. PROJECT NUMBER 5e. TASK NUMBER...34) 27-02-2001 Report Type N/A Dates Covered (from... to) ("DD MON YYYY") 28-10-2000 27-02-2001 Title and Subtitle Artificial Neural Network Analysis

  6. Cooperating attackers in neural cryptography.

    Science.gov (United States)

    Shacham, Lanir N; Klein, Einat; Mislovaty, Rachel; Kanter, Ido; Kinzel, Wolfgang

    2004-06-01

    A successful attack strategy in neural cryptography is presented. The neural cryptosystem, based on synchronization of neural networks by mutual learning, has been recently shown to be secure under different attack strategies. The success of the advanced attacker presented here, called the "majority-flipping attacker," does not decay with the parameters of the model. This attacker's outstanding success is due to its using a group of attackers which cooperate throughout the synchronization process, unlike any other attack strategy known. An analytical description of this attack is also presented, and fits the results of simulations.

  7. A complex between contactin-1 and the protein tyrosine phosphatase PTPRZ controls the development of oligodendrocyte precursor cells

    Energy Technology Data Exchange (ETDEWEB)

    Lamprianou, Smaragda; Chatzopoulou, Elli; Thomas, Jean-Léon; Bouyain, Samuel; Harroch, Sheila (IP-Korea); (UPMC); (UMKC)

    2013-09-23

    The six members of the contactin (CNTN) family of neural cell adhesion molecules are involved in the formation and maintenance of the central nervous system (CNS) and have been linked to mental retardation and neuropsychiatric disorders such as autism. Five of the six CNTNs bind to the homologous receptor protein tyrosine phosphatases gamma (PTPRG) and zeta (PTPRZ), but the biological roles of these interactions remain unclear. We report here the cocrystal structure of the carbonic anhydrase-like domain of PTPRZ bound to tandem Ig repeats of CNTN1 and combine these structural data with binding assays to show that PTPRZ binds specifically to CNTN1 expressed at the surface of oligodendrocyte precursor cells. Furthermore, analyses of glial cell populations in wild-type and PTPRZ-deficient mice show that the binding of PTPRZ to CNTN1 expressed at the surface of oligodendrocyte precursor cells inhibits their proliferation and promotes their development into mature oligodendrocytes. Overall, these results implicate the PTPRZ/CNTN1 complex as a previously unknown modulator of oligodendrogenesis.

  8. The β-chemokines CCL2 and CCL7 are two novel differentiation factors for midbrain dopaminergic precursors and neurons

    International Nuclear Information System (INIS)

    Edman, Linda C.; Mira, Helena; Arenas, Ernest

    2008-01-01

    β-chemokines are secreted factors that regulate diverse functions in the adult brain, such as neuro-immune responses and neurotransmission, but their function in the developing brain is largely unknown. We recently found that the orphan nuclear receptor, Nurr1, up regulates CCL2 and CCL7 in neural stem cells, suggesting a possible function of β-chemokines in midbrain development. Here we report that two β-chemokines, CCL2 and CCL7, and two of their receptors, CCR1 and CCR2, are expressed and developmentally regulated in the ventral midbrain (VM). Moreover, we found that the expression of CCL7 was down regulated in the Nurr1 knockout mice, linking CCL7 to dopamine (DA) neuron development. When the function of CCL2 and CCL7 was examined, we found that they selectively enhanced the differentiation of Nurr1+ precursors into DA neurons, but not their survival or progenitor proliferation in primary precursor cultures. Moreover, both CCL2 and CCL7 promoted neuritogenesis in midbrain DA neuron cultures. Thus, our results show for the first time a function of β-chemokines in the developing brain and identify β-chemokines as novel class of pro-differentiation factors for midbrain DA neurons. These data also suggest that β-chemokines may become useful tools to enhance the differentiation of DA cell preparations for cell replacement therapy and drug discovery in Parkinson's disease (PD)

  9. Behavioral and Neurodevelopmental Precursors to Binge-Type Eating Disorders: Support for the Role of Negative Valence Systems

    Science.gov (United States)

    Vannucci, Anna; Nelson, Eric E.; Bongiorno, Diana M.; Pine, Daniel S.; Yanovski, Jack A.; Tanofsky-Kraff, Marian

    2015-01-01

    Background Pediatric loss-of-control eating is a robust behavioral precursor to binge-type eating disorders. Elucidating precursors to loss-of-control eating and binge-type eating disorders may refine developmental risk models of eating disorders and inform interventions. Method We review evidence within constructs of the Negative Valence Systems (NVS)-domain, as specified by the Research Domain Criteria framework. Based on published studies, we propose an integrated NVS model of binge-type eating disorder risk. Results Data implicate altered corticolimbic functioning, neuroendocrine dysregulation, and self-reported negative affect as possible risk-factors. However, neuroimaging and physiological data in children and adolescents are sparse, and most prospective studies are limited to self-report measures. Conclusions We discuss a broad NVS framework for conceptualizing early risk for binge-type eating disorders. Future neural and behavioral research on the developmental trajectory of loss-of-control and binge-type eating disorders is required. PMID:26040923

  10. Whole-cell fungal transformation of precursors into dyes

    Directory of Open Access Journals (Sweden)

    Jarosz-Wilkołazka Anna

    2010-07-01

    Full Text Available Abstract Background Chemical methods of producing dyes involve extreme temperatures and unsafe toxic compounds. Application of oxidizing enzymes obtained from fungal species, for example laccase, is an alternative to chemical synthesis of dyes. Laccase can be replaced by fungal biomass acting as a whole-cell biocatalyst with properties comparable to the isolated form of the enzyme. The application of the whole-cell system simplifies the transformation process and reduces the time required for its completion. In the present work, four fungal strains with a well-known ability to produce laccase were tested for oxidation of 17 phenolic and non-phenolic precursors into stable and non-toxic dyes. Results An agar-plate screening test of the organic precursors was carried out using four fungal strains: Trametes versicolor, Fomes fomentarius, Abortiporus biennis, and Cerrena unicolor. Out of 17 precursors, nine were transformed into coloured substances in the presence of actively growing fungal mycelium. The immobilized fungal biomass catalyzed the transformation of 1 mM benzene and naphthalene derivatives in liquid cultures yielding stable and non-toxic products with good dyeing properties. The type of fungal strain had a large influence on the absorbance of the coloured products obtained after 48-hour transformation of the selected precursors, and the most effective was Fomes fomentarius (FF25. Whole-cell transformation of AHBS (3-amino-4-hydroxybenzenesulfonic acid into a phenoxazinone dye was carried out in four different systems: in aqueous media comprising low amounts of carbon and nitrogen source, in buffer, and in distilled water. Conclusions This study demonstrated the ability of four fungal strains belonging to the ecological type of white rot fungi to transform precursors into dyes. This paper highlights the potential of fungal biomass for replacing isolated enzymes as a cheaper industrial-grade biocatalyst for the synthesis of dyes and other

  11. Creative-Dynamics Approach To Neural Intelligence

    Science.gov (United States)

    Zak, Michail A.

    1992-01-01

    Paper discusses approach to mathematical modeling of artificial neural networks exhibiting complicated behaviors reminiscent of creativity and intelligence of biological neural networks. Neural network treated as non-Lipschitzian dynamical system - as described in "Non-Lipschitzian Dynamics For Modeling Neural Networks" (NPO-17814). System serves as tool for modeling of temporal-pattern memories and recognition of complicated spatial patterns.

  12. Planning chemical syntheses with deep neural networks and symbolic AI

    Science.gov (United States)

    Segler, Marwin H. S.; Preuss, Mike; Waller, Mark P.

    2018-03-01

    To plan the syntheses of small organic molecules, chemists use retrosynthesis, a problem-solving technique in which target molecules are recursively transformed into increasingly simpler precursors. Computer-aided retrosynthesis would be a valuable tool but at present it is slow and provides results of unsatisfactory quality. Here we use Monte Carlo tree search and symbolic artificial intelligence (AI) to discover retrosynthetic routes. We combined Monte Carlo tree search with an expansion policy network that guides the search, and a filter network to pre-select the most promising retrosynthetic steps. These deep neural networks were trained on essentially all reactions ever published in organic chemistry. Our system solves for almost twice as many molecules, thirty times faster than the traditional computer-aided search method, which is based on extracted rules and hand-designed heuristics. In a double-blind AB test, chemists on average considered our computer-generated routes to be equivalent to reported literature routes.

  13. Epithelial–Mesenchymal Transitions during Neural Crest and Somite Development

    Directory of Open Access Journals (Sweden)

    Chaya Kalcheim

    2015-12-01

    Full Text Available Epithelial-to-mesenchymal transition (EMT is a central process during embryonic development that affects selected progenitor cells of all three germ layers. In addition to driving the onset of cellular migrations and subsequent tissue morphogenesis, the dynamic conversions of epithelium into mesenchyme and vice-versa are intimately associated with the segregation of homogeneous precursors into distinct fates. The neural crest and somites, progenitors of the peripheral nervous system and of skeletal tissues, respectively, beautifully illustrate the significance of EMT to the above processes. Ongoing studies progressively elucidate the gene networks underlying EMT in each system, highlighting the similarities and differences between them. Knowledge of the mechanistic logic of this normal ontogenetic process should provide important insights to the understanding of pathological conditions such as cancer metastasis, which shares some common molecular themes.

  14. Vascular pattern of the dentate gyrus is regulated by neural progenitors.

    Science.gov (United States)

    Pombero, Ana; Garcia-Lopez, Raquel; Estirado, Alicia; Martinez, Salvador

    2018-05-01

    Neurogenesis is a vital process that begins during early embryonic development and continues until adulthood, though in the latter case, it is restricted to the subventricular zone and the subgranular zone of the dentate gyrus (DG). In particular, the DG's neurogenic properties are structurally and functionally unique, which may be related to its singular vascular pattern. Neurogenesis and angiogenesis share molecular signals and act synergistically, supporting the concept of a neurogenic niche as a functional unit between neural precursors cells and their environment, in which the blood vessels play an important role. Whereas it is well known that vascular development controls neural proliferation in the embryonary and in the adult brain, by releasing neurotrophic factors; the potential influence of neural cells on vascular components during angiogenesis is largely unknown. We have demonstrated that the reduction of neural progenitors leads to a significant impairment of vascular development. Since VEGF is a potential regulator in the neurogenesis-angiogenesis crosstalk, we were interested in assessing the possible role of this molecule in the hippocampal neurovascular development. Our results showed that VEGF is the molecule involved in the regulation of vascular development by neural progenitor cells in the DG.

  15. Neural components of altruistic punishment

    Directory of Open Access Journals (Sweden)

    Emily eDu

    2015-02-01

    Full Text Available Altruistic punishment, which occurs when an individual incurs a cost to punish in response to unfairness or a norm violation, may play a role in perpetuating cooperation. The neural correlates underlying costly punishment have only recently begun to be explored. Here we review the current state of research on the neural basis of altruism from the perspectives of costly punishment, emphasizing the importance of characterizing elementary neural processes underlying a decision to punish. In particular, we emphasize three cognitive processes that contribute to the decision to altruistically punish in most scenarios: inequity aversion, cost-benefit calculation, and social reference frame to distinguish self from others. Overall, we argue for the importance of understanding the neural correlates of altruistic punishment with respect to the core computations necessary to achieve a decision to punish.

  16. Neural complexity, dissociation, and schizophrenia

    Czech Academy of Sciences Publication Activity Database

    Bob, P.; Šusta, M.; Chládek, Jan; Glaslová, K.; Fedor-Ferybergh, P.

    2007-01-01

    Roč. 13, č. 10 (2007), HY1-5 ISSN 1234-1010 Institutional research plan: CEZ:AV0Z20650511 Keywords : neural complexity * dissociation * schizophrenia Subject RIV: FH - Neurology Impact factor: 1.607, year: 2007

  17. Neural Networks in Control Applications

    DEFF Research Database (Denmark)

    Sørensen, O.

    The intention of this report is to make a systematic examination of the possibilities of applying neural networks in those technical areas, which are familiar to a control engineer. In other words, the potential of neural networks in control applications is given higher priority than a detailed...... study of the networks themselves. With this end in view the following restrictions have been made: - Amongst numerous neural network structures, only the Multi Layer Perceptron (a feed-forward network) is applied. - Amongst numerous training algorithms, only four algorithms are examined, all...... in a recursive form (sample updating). The simplest is the Back Probagation Error Algorithm, and the most complex is the recursive Prediction Error Method using a Gauss-Newton search direction. - Over-fitting is often considered to be a serious problem when training neural networks. This problem is specifically...

  18. Complex-Valued Neural Networks

    CERN Document Server

    Hirose, Akira

    2012-01-01

    This book is the second enlarged and revised edition of the first successful monograph on complex-valued neural networks (CVNNs) published in 2006, which lends itself to graduate and undergraduate courses in electrical engineering, informatics, control engineering, mechanics, robotics, bioengineering, and other relevant fields. In the second edition the recent trends in CVNNs research are included, resulting in e.g. almost a doubled number of references. The parametron invented in 1954 is also referred to with discussion on analogy and disparity. Also various additional arguments on the advantages of the complex-valued neural networks enhancing the difference to real-valued neural networks are given in various sections. The book is useful for those beginning their studies, for instance, in adaptive signal processing for highly functional sensing and imaging, control in unknown and changing environment, robotics inspired by human neural systems, and brain-like information processing, as well as interdisciplina...

  19. Artificial intelligence: Deep neural reasoning

    Science.gov (United States)

    Jaeger, Herbert

    2016-10-01

    The human brain can solve highly abstract reasoning problems using a neural network that is entirely physical. The underlying mechanisms are only partially understood, but an artificial network provides valuable insight. See Article p.471

  20. Optical Neural Network Classifier Architectures

    National Research Council Canada - National Science Library

    Getbehead, Mark

    1998-01-01

    We present an adaptive opto-electronic neural network hardware architecture capable of exploiting parallel optics to realize real-time processing and classification of high-dimensional data for Air...

  1. Memristor-based neural networks

    International Nuclear Information System (INIS)

    Thomas, Andy

    2013-01-01

    The synapse is a crucial element in biological neural networks, but a simple electronic equivalent has been absent. This complicates the development of hardware that imitates biological architectures in the nervous system. Now, the recent progress in the experimental realization of memristive devices has renewed interest in artificial neural networks. The resistance of a memristive system depends on its past states and exactly this functionality can be used to mimic the synaptic connections in a (human) brain. After a short introduction to memristors, we present and explain the relevant mechanisms in a biological neural network, such as long-term potentiation and spike time-dependent plasticity, and determine the minimal requirements for an artificial neural network. We review the implementations of these processes using basic electric circuits and more complex mechanisms that either imitate biological systems or could act as a model system for them. (topical review)

  2. Antarctic new particle formation from continental biogenic precursors

    Directory of Open Access Journals (Sweden)

    E.-M. Kyrö

    2013-04-01

    Full Text Available Over Antarctica, aerosol particles originate almost entirely from marine areas, with minor contribution from long-range transported dust or anthropogenic material. The Antarctic continent itself, unlike all other continental areas, has been thought to be practically free of aerosol sources. Here we present evidence of local aerosol production associated with melt-water ponds in continental Antarctica. We show that in air masses passing such ponds, new aerosol particles are efficiently formed and these particles grow up to sizes where they may act as cloud condensation nuclei (CCN. The precursor vapours responsible for aerosol formation and growth originate very likely from highly abundant cyanobacteria Nostoc commune (Vaucher communities of local ponds. This is the first time freshwater vegetation has been identified as an aerosol precursor source. The influence of the new source on clouds and climate may increase in future Antarctica, and possibly elsewhere undergoing accelerating summer melting of semi-permanent snow cover.

  3. Amplitude of foreshocks as a possible seismic precursor to earthquakes

    Science.gov (United States)

    Lindh, A.G.

    1978-01-01

    In recent years, we have made significant progress in being able to recognize the long-range pattern of events that precede large earthquakes. For example, in a recent issue of the Earthquake Information Bulletin, we saw how the pioneering work of S.A. Fedotov of the U.S.S.R in the Kamchatka-Kurile Islands region has been applied worldwide to forecast where large, shallow earthquakes might occur in the next decades. Indeed, such a "seismic gap" off the coast of Alaska was filled by the 1972 Sitka earthquake. Promising results are slowly accumulating from other techniques that suggest that intermediate-term precursors might also be seen: among these are tilt and geomagnetic anomalies and anomalous land uplift. But the crucial point remains that short-term precursors (days to hours) will be needed in many cases if there is to be a significant saving of lives. 

  4. Creep and slip: Seismic precursors to the Nuugaatsiaq landslide (Greenland)

    Science.gov (United States)

    Poli, Piero

    2017-09-01

    Precursory signals to material's failure are predicted by numerical models and observed in laboratory experiments or using field data. These precursory signals are a marker of slip acceleration on weak regions, such as crustal faults. Observation of these precursory signals of catastrophic natural events, such as earthquakes and landslides, is necessary for improving our knowledge about the physics of the nucleation process. Furthermore, observing such precursory signals may help to forecast these catastrophic events or reduce their hazard. I report here the observation of seismic precursors to the Nuugaatsiaq landslide in Greenland. Time evolution of the detected precursors implies that an aseismic slip event is taking place for hours before the landslide, with an exponential increase of slip velocity. Furthermore, time evolution of the precursory signals' amplitude sheds light on the evolution of the fault physics during the nucleation process.

  5. The Accident Sequence Precursor program: Methods improvements and current results

    International Nuclear Information System (INIS)

    Minarick, J.W.; Manning, F.M.; Harris, J.D.

    1987-01-01

    Changes in the US NRC Accident Sequence Precursor program methods since the initial program evaluations of 1969-81 operational events are described, along with insights from the review of 1984-85 events. For 1984-85, the number of significant precursors was consistent with the number observed in 1980-81, dominant sequences associated with significant events were reasonably consistent with PRA estimates for BWRs, but lacked the contribution due to small-break LOCAs previously observed and predicted in PWRs, and the frequency of initiating events and non-recoverable system failures exhibited some reduction compared to 1980-81. Operational events which provide information concerning additional PRA modeling needs are also described

  6. Antarctic new particle formation from continental biogenic precursors

    Science.gov (United States)

    Kyrö, E.-M.; Kerminen, V.-M.; Virkkula, A.; Dal Maso, M.; Parshintsev, J.; Ruíz-Jimenez, J.; Forsström, L.; Manninen, H. E.; Riekkola, M.-L.; Heinonen, P.; Kulmala, M.

    2013-04-01

    Over Antarctica, aerosol particles originate almost entirely from marine areas, with minor contribution from long-range transported dust or anthropogenic material. The Antarctic continent itself, unlike all other continental areas, has been thought to be practically free of aerosol sources. Here we present evidence of local aerosol production associated with melt-water ponds in continental Antarctica. We show that in air masses passing such ponds, new aerosol particles are efficiently formed and these particles grow up to sizes where they may act as cloud condensation nuclei (CCN). The precursor vapours responsible for aerosol formation and growth originate very likely from highly abundant cyanobacteria Nostoc commune (Vaucher) communities of local ponds. This is the first time freshwater vegetation has been identified as an aerosol precursor source. The influence of the new source on clouds and climate may increase in future Antarctica, and possibly elsewhere undergoing accelerating summer melting of semi-permanent snow cover.

  7. Seismic-electromagnetic precursors of Romania's Vrancea earthquakes

    International Nuclear Information System (INIS)

    Enescu, B.D.; Enescu, C.; Constantin, A. P.

    1999-01-01

    Diagrams were plotted from electromagnetic data that were recorded at Muntele Rosu Observatory during December 1996 to January 1997, and December 1997 to September 1998. The times when Vrancea earthquakes of magnitudes M ≥ 3.9 occurred within these periods are marked on the diagrams.The parameters of the earthquakes are given in a table which also includes information on the magnetic and electric anomalies (perturbations) preceding these earthquakes. The magnetic data prove that Vrancea earthquakes are preceded by magnetic perturbations that may be regarded as their short-term precursors. Perturbations, which could likewise be seen as short-term precursors of Vrancea earthquakes, are also noticed in the electric records. Still, a number of electric data do cast a doubt on their forerunning nature. Some suggestions are made in the end of the paper on how electromagnetic research should go ahead to be of use for Vrancea earthquake prediction. (authors)

  8. PREPARATION OF TANTALUM CARBIDE FROM AN ORGANOMETALLIC PRECURSOR

    Directory of Open Access Journals (Sweden)

    C. P. SOUZA

    1999-03-01

    Full Text Available In this work we have synthesized an organometallic oxalic precursor from tantalum oxide. This oxide was solubilized by heating with potassium hydrogen sulfate. In order to precipitate Ta2O5.nH2O, the fused mass obtained was dissolved in a sulfuric acid solution and neutralized with ammonia. The hydrated tantalum oxide precipitated was dissolved in an equimolar solution of oxalic acid/ammonium oxalate. The synthesis and the characterization of the tantalum oxalic precursor are described. Pyrolysis of the complex in a mixture of hydrogen and methane at atmospheric pressure was studied. The gas-solid reaction made it possible to obtain tantalum carbide, TaC, in the powder form at 1000oC. The natural sintering of TaC powder in an inert atmosphere at 1400°C during 10 hours, under inert atmosphere made it possible to densify the carbide to 96% of the theoretical value.

  9. Helper T lymphocyte precursor frequency analysis in alloreactivity detection

    International Nuclear Information System (INIS)

    Cukrova, V.; Dolezalova, L.; Loudova, M.; Vitek, A.

    1998-01-01

    The utility of IL-2 secreting helper T lymphocyte precursors (HTLp) frequency testing has been evaluated for detecting alloreactivity. The frequency of HTLp was approached by limiting dilution assay. High HTLp frequency was detected in 20 out of 30 HLA matched unrelated pairs (67%). The comparison of HTLp and CTLp (cytotoxic T lymphocyte precursors) frequencies in HLA matched unrelated pairs showed that the two examinations are not fully alternative in detecting alloreactivity. This could suggest the utility of combined testing of both HTLp and CTLp frequencies for alloreactivity assessment. In contrast, five positive HTLp values were only found among 28 HLA genotypic identical siblings (18%). Previous CTLp limiting dilution studies showed very low or undetectable CTLp frequency results in that group. For that, HTLp assay remains to be the only cellular in vitro technique detecting alloreactivity in these combinations. (authors)

  10. Structural basis for precursor protein-directed ribosomal peptide macrocyclization

    Science.gov (United States)

    Li, Kunhua; Condurso, Heather L.; Li, Gengnan; Ding, Yousong; Bruner, Steven D.

    2016-01-01

    Macrocyclization is a common feature of natural product biosynthetic pathways including the diverse family of ribosomal peptides. Microviridins are architecturally complex cyanobacterial ribosomal peptides whose members target proteases with potent reversible inhibition. The product structure is constructed by three macrocyclizations catalyzed sequentially by two members of the ATP-grasp family, a unique strategy for ribosomal peptide macrocyclization. Here, we describe the detailed structural basis for the enzyme-catalyzed macrocyclizations in the microviridin J pathway of Microcystis aeruginosa. The macrocyclases, MdnC and MdnB, interact with a conserved α-helix of the precursor peptide using a novel precursor peptide recognition mechanism. The results provide insight into the unique protein/protein interactions key to the chemistry, suggest an origin of the natural combinatorial synthesis of microviridin peptides and provide a framework for future engineering efforts to generate designed compounds. PMID:27669417

  11. Structural basis for precursor protein-directed ribosomal peptide macrocyclization.

    Science.gov (United States)

    Li, Kunhua; Condurso, Heather L; Li, Gengnan; Ding, Yousong; Bruner, Steven D

    2016-11-01

    Macrocyclization is a common feature of natural product biosynthetic pathways including the diverse family of ribosomal peptides. Microviridins are architecturally complex cyanobacterial ribosomal peptides that target proteases with potent reversible inhibition. The product structure is constructed via three macrocyclizations catalyzed sequentially by two members of the ATP-grasp family, a unique strategy for ribosomal peptide macrocyclization. Here we describe in detail the structural basis for the enzyme-catalyzed macrocyclizations in the microviridin J pathway of Microcystis aeruginosa. The macrocyclases MdnC and MdnB interact with a conserved α-helix of the precursor peptide using a novel precursor-peptide recognition mechanism. The results provide insight into the unique protein-protein interactions that are key to the chemistry, suggest an origin for the natural combinatorial synthesis of microviridin peptides, and provide a framework for future engineering efforts to generate designed compounds.

  12. Structural phase transition and precursor phenomena in V3Si

    International Nuclear Information System (INIS)

    Kobayashi, T.; Fukase, T.; Toyota, N.; Muto, Y.

    1982-01-01

    Thermal dilation experiments on the transforming single crystals V 3 Si indicated that the precursor of the structural transformation at Tsub(m) of about 21 K starts at anomalously high temperatures (proportional70 K) and grows drastically near Tsub(m). This anomaly is also accompanied by the critical increment of electrical resistivity showing a sharp peak at Tsub(m). The application of the uniaxial stress suppresses the resistivity anomaly and makes the superconducting transition width narrower. We propose a model for the precursor phenomena in terms of (1) the directional strain fields (non-cubic) pinned near the defects and (2) the memory effect of orientation of the tetragonal domains born by the defects such as dislocations. (orig.)

  13. Fission-Based Electric Propulsion for Interstellar Precursor Missions

    International Nuclear Information System (INIS)

    HOUTS, MICHAEL G.; LENARD, ROGER X.; LIPINSKI, RONALD J.; PATTON, BRUCE; POSTON, DAVID; WRIGHT, STEVEN A.

    1999-01-01

    This paper reviews the technology options for a fission-based electric propulsion system for interstellar precursor missions. To achieve a total ΔV of more than 100 km/s in less than a decade of thrusting with an electric propulsion system of 10,000s Isp requires a specific mass for the power system of less than 35 kg/kWe. Three possible configurations are described: (1) a UZrH-fueled,NaK-cooled reactor with a steam Rankine conversion system,(2) a UN-fueled gas-cooled reactor with a recuperated Brayton conversion system, and (3) a UN-fueled heat pipe-cooled reactor with a recuperated Brayton conversion system. All three of these systems have the potential to meet the specific mass requirements for interstellar precursor missions in the near term. Advanced versions of a fission-based electric propulsion system might travel as much as several light years in 200 years

  14. Possible precursors to the 2011 3/11 Japan earthquake:

    Science.gov (United States)

    Hayakawa, M.; Hobara, Y.; Schekotov, A.; Rozhnoi, A.; Solovieva, M.

    2012-04-01

    The purpose of this paper is to present a possible precursor to the 2011 March 11 Japan earthquake. First of all, we present the results on subionospheric VLF/LF propagation anomaly (ionospheric perturbation) by means of Japan-Russia VLF network. It is found that the ionospheric perturbation is clearly detected on March 4, 5 and 6 on the propagation paths of NLK (Seattle, USA) to Japanese stations and on a path of JJI (Miyazaki, Kyushu) to Kamchatka. Next, we present the results on the ULF depression (horizontal component) on the same days, which is interpreted in terms of the absorption in the disturbed lower ionosphere of the downgoing magnetospheric Alfve'n waves. These two precursors are considered to be due to the same effect of the lower ionospheric perturbation about one week before the earthquake.

  15. CD133 (Prominin negative human neural stem cells are clonogenic and tripotent.

    Directory of Open Access Journals (Sweden)

    Yirui Sun

    Full Text Available CD133 (Prominin is widely used as a marker for the identification and isolation of neural precursor cells from normal brain or tumor tissue. However, the assumption that CD133 is expressed constitutively in neural precursor cells has not been examined.In this study, we demonstrate that CD133 and a second marker CD15 are expressed heterogeneously in uniformly undifferentiated human neural stem (NS cell cultures. After fractionation by flow cytometry, clonogenic tripotent cells are found in populations negative or positive for either marker. We further show that CD133 is down-regulated at the mRNA level in cells lacking CD133 immunoreactivity. Cell cycle profiling reveals that CD133 negative cells largely reside in G1/G0, while CD133 positive cells are predominantly in S, G2, or M phase. A similar pattern is apparent in mouse NS cell lines. Compared to mouse NS cells, however, human NS cell cultures harbour an increased proportion of CD133 negative cells and display a longer doubling time. This may in part reflect a sub-population of slow- or non-cycling cells amongst human NS cells because we find that around 5% of cells do not take up BrdU over a 14-day labelling period. Non-proliferating NS cells remain undifferentiated and at least some of them are capable of re-entry into the cell cycle and subsequent continuous expansion.The finding that a significant fraction of clonogenic neural stem cells lack the established markers CD133 and CD15, and that some of these cells may be dormant or slow-cycling, has implications for approaches to identify and isolate neural stem cells and brain cancer stem cells. Our data also suggest the possibility that CD133 may be specifically down-regulated during G0/G1, and this should be considered when this marker is used to identify and isolate other tissue and cancer stem cells.

  16. Sequential neural models with stochastic layers

    DEFF Research Database (Denmark)

    Fraccaro, Marco; Sønderby, Søren Kaae; Paquet, Ulrich

    2016-01-01

    How can we efficiently propagate uncertainty in a latent state representation with recurrent neural networks? This paper introduces stochastic recurrent neural networks which glue a deterministic recurrent neural network and a state space model together to form a stochastic and sequential neural...... generative model. The clear separation of deterministic and stochastic layers allows a structured variational inference network to track the factorization of the model's posterior distribution. By retaining both the nonlinear recursive structure of a recurrent neural network and averaging over...

  17. Thin films by metal-organic precursor plasma spray

    International Nuclear Information System (INIS)

    Schulz, Douglas L.; Sailer, Robert A.; Payne, Scott; Leach, James; Molz, Ronald J.

    2009-01-01

    While most plasma spray routes to coatings utilize solids as the precursor feedstock, metal-organic precursor plasma spray (MOPPS) is an area that the authors have investigated recently as a novel route to thin film materials. Very thin films are possible via MOPPS and the technology offers the possibility of forming graded structures by metering the liquid feed. The current work employs metal-organic compounds that are liquids at standard temperature-pressure conditions. In addition, these complexes contain chemical functionality that allows straightforward thermolytic transformation to targeted phases of interest. Toward that end, aluminum 3,5-heptanedionate (Al(hd) 3 ), triethylsilane (HSi(C 2 H 5 ) 3 or HSiEt 3 ), and titanium tetrakisdiethylamide (Ti(N(C 2 H 5 ) 2 ) 4 or Ti(NEt 2 ) 4 ) were employed as precursors to aluminum oxide, silicon carbide, and titanium nitride, respectively. In all instances, the liquids contain metal-heteroatom bonds envisioned to provide atomic concentrations of the appropriate reagents at the film growth surface, thus promoting phase formation (e.g., Si-C bond in triethylsilane, Ti-N bond in titanium amide, etc.). Films were deposited using a Sulzer Metco TriplexPro-200 plasma spray system under various experimental conditions using design of experiment principles. Film compositions were analyzed by glazing incidence x-ray diffraction and elemental determination by x-ray spectroscopy. MOPPS films from HSiEt 3 showed the formation of SiC phase but Al(hd) 3 -derived films were amorphous. The Ti(NEt 2 ) 4 precursor gave MOPPS films that appear to consist of nanosized splats of TiOCN with spheres of TiO 2 anatase. While all films in this study suffered from poor adhesion, it is anticipated that the use of heated substrates will aid in the formation of dense, adherent films.

  18. Pollutants removal onto novel activated carbons made from lignocellulosic precursors

    OpenAIRE

    Valente Nabais, Joao; Laginhas, Carlos; Carrott, Manuela; Carrott, Peter; Gomes, Jose; Suhas, Suhas; Ramires, Ana; Roman, Silvia

    2009-01-01

    The adsorption of phenol and mercury from dilute aqueous solutions onto new activated carbons was studied. These included activated carbons produced from novel precursors, namely rapeseed, vine shoots and kenaf, and samples oxidised with nitric acid in liquid phase. The results have shown the significant potential of rapeseed, vine shoots and kenaf for the activated carbon production. The activated carbons produced by carbon dioxide activation were mainly microporous with BET apparent surface...

  19. Effect of precursors on flavonoid production by Hydrocotyle ...

    African Journals Online (AJOL)

    Callus tissue of Hydrocotyle bonariensis was initiated from the leaf of H. bonariensis treated with 2 mg/l of 2,4-dichlorophenoxyacetic acid (2,4-D) and 1 mg/l kinetin. The culture was kept at 25°C, under light (cool white fluorescent tubes, 1200 lux). To optimize the precursors to increase the production of flavonoid, different ...

  20. New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Daria L. [Department of Chemistry, Yale University, 225; Beltrán-Suito, Rodrigo [Department of Chemistry, Yale University, 225; Thomsen, Julianne M. [Department of Chemistry, Yale University, 225; Hashmi, Sara M. [Department of Chemical and Environmental; Materna, Kelly L. [Department of Chemistry, Yale University, 225; Sheehan, Stafford W. [Catalytic Innovations LLC, 70 Crandall; Mercado, Brandon Q. [Department of Chemistry, Yale University, 225; Brudvig, Gary W. [Department of Chemistry, Yale University, 225; Crabtree, Robert H. [Department of Chemistry, Yale University, 225

    2016-02-05

    This paper introduces IrI(CO)2(pyalc) (pyalc = (2-pyridyl)-2-propanoate) as an atom-efficient precursor for Ir-based homogeneous oxidation catalysis. This compound was chosen to simplify analysis of the water oxidation catalyst species formed by the previously reported Cp*IrIII(pyalc)OH water oxidation precatalyst. Here, we present a comparative study on the chemical and catalytic properties of these two precursors. Previous studies show that oxidative activation of Cp*Ir-based precursors with NaIO4 results in formation of a blue IrIV species. This activation is concomitant with the loss of the placeholder Cp* ligand which oxidatively degrades to form acetic acid, iodate, and other obligatory byproducts. The activation process requires substantial amounts of primary oxidant, and the degradation products complicate analysis of the resulting IrIV species. The species formed from oxidation of the Ir(CO)2(pyalc) precursor, on the other hand, lacks these degradation products (the CO ligands are easily lost upon oxidation) which allows for more detailed examination of the resulting Ir(pyalc) active species both catalytically and spectroscopically, although complete structural analysis is still elusive. Once Ir(CO)2(pyalc) is activated, the system requires acetic acid or acetate to prevent the formation of nanoparticles. Investigation of the activated bis-carbonyl complex also suggests several Ir(pyalc) isomers may exist in solution. By 1H NMR, activated Ir(CO)2(pyalc) has fewer isomers than activated Cp*Ir complexes, allowing for advanced characterization. Future research in this direction is expected to contribute to a better structural understanding of the active species. A diol crystallization agent was needed for the structure determination of 3.

  1. MHD precursor to disruption in Iran tokamak 1

    International Nuclear Information System (INIS)

    Alireza, Hojabri; Fatemeh, Hajakbari; Alireza, Hojabri; Mahmmod, Ghoranneviss; Fatemeh, Hajakbari

    2004-01-01

    The purpose of this paper is to investigate the major disruptions occurring in low-q(a) discharges in Iran Tokamak 1, and to compare the theoretical and experimental results for the rate of island growth. The study of precursor phase of disruption can be predicted and avoided using suitable control systems. In this paper are described the stability analysis and the observed growth rates indicating that the rotating modes are tearing modes. (authors)

  2. The miR-10 microRNA precursor family

    DEFF Research Database (Denmark)

    Tehler, Disa; Høyland-Kroghsbo, Nina Molin; Lund, Anders H

    2011-01-01

    The miR-10 microRNA precursor family encodes a group of short non-coding RNAs involved in gene regulation. The miR-10 family is highly conserved and has sparked the interest of many research groups because of the genomic localization in the vicinity of, coexpression with and regulation of the Hox...... gene developmental regulators. Here, we review the current knowledge of the evolution, physiological function and involvement in cancer of this family of microRNAs....

  3. Hemopoietic cell precursor responses to erythropoietin in plasma clot cultures

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, W.L.

    1979-01-01

    The time dependence of the response of mouse bone marrow cells to erythropoietin (Ep) in vitro was studied. Experiments include studies on the Ep response of marrow cells from normal, plethoric, or bled mice. Results with normal marrow reveal: (1) Not all erythroid precursors (CFU-E) are alike in their response to Ep. A significant number of the precursors develop to a mature erythroid colony after very short Ep exposures, but they account for only approx. 13% of the total colonies generated when Ep is active for 48 hrs. If Ep is active more than 6 hrs, a second population of erythroid colonies emerges at a nearly constant rate until the end of the culture. Full erythroid colony production requires prolonged exposure to erythropoietin. (2) The longer erythropoietin is actively present, the larger the number of erythroid colonies that reach 17 cells or more. Two distinct populations of immediate erythroid precursors are also present in marrow from plethoric mice. In these mice, total colony numbers are equal to or below those obtained from normal mice. However, the population of fast-responding CFU-E is consistently decreased to 10 to 20% of that found in normal marrow. The remaining colonies are formed from plethoric marrow at a rate equal to normal marrow. With increasing Ep exposures, the number of large colonies produced increases. From the marrow of bled mice, total erythroid colony production is equal to or above that of normal marrow. Two populations of colony-forming cells are again evident, with the fast-responding CFU-E being below normal levels. The lack of colonies from this group was compensated in bled mice by rapid colony production in the second population. A real increase in numbers of precursors present in this pool increased the rate of colony production in culture to twice that of normal marrow. The number of large colonies obtained from bled mice was again increased as the Ep exposure was lengthened. (ERB)

  4. Nuclear critical opalescence, a precursor to pion condensation

    International Nuclear Information System (INIS)

    Ericson, M.; Delorme, J.

    1978-03-01

    It is shown that pion condensation in nuclei, a long range phenomenon, has a precursor in the disordered phase, the local ordering of spins which becomes of infinite range at the critical point. A new physical effect arising from this short range order is predicted, namely the enhancement of the static nuclear pion field near the critical momentum. This phenomenon is strongly reminiscent of the critical opalescence observed in the scattering of neutrons by antiferromagnetic subtances

  5. Nuclear critical opalescence, a precursor to pion condensation

    International Nuclear Information System (INIS)

    Ericson, M.; Delorme, J.

    1978-01-01

    It is shown that pion condensation in nuclei, a long-range phenomenon, has a precursor in the disordered phase, the local ordering of spins which becomes of infinite range at the critical point. A new physical effect arising from this short-range order is predicted, namely the enhancement of the static nuclear pion field near the critical momentum. This phenomenon is strongly reminiscent of the critical opalescence observed in the scattering of neutrons by antiferromagnetic substances. (Auth.)

  6. Implantable Neural Interfaces for Sharks

    Science.gov (United States)

    2007-05-01

    technology for recording and stimulating from the auditory and olfactory sensory nervous systems of the awake, swimming nurse shark , G. cirratum (Figures...overlay of the central nervous system of the nurse shark on a horizontal MR image. Implantable Neural Interfaces for Sharks ...Neural Interfaces for Characterizing Population Responses to Odorants and Electrical Stimuli in the Nurse Shark , Ginglymostoma cirratum.” AChemS Abs

  7. What are artificial neural networks?

    DEFF Research Database (Denmark)

    Krogh, Anders

    2008-01-01

    Artificial neural networks have been applied to problems ranging from speech recognition to prediction of protein secondary structure, classification of cancers and gene prediction. How do they work and what might they be good for? Udgivelsesdato: 2008-Feb......Artificial neural networks have been applied to problems ranging from speech recognition to prediction of protein secondary structure, classification of cancers and gene prediction. How do they work and what might they be good for? Udgivelsesdato: 2008-Feb...

  8. Progress in the prediction of disruptions in ASDEX-Upgrade via neural and fuzzy-neural techniques

    International Nuclear Information System (INIS)

    Versaci, M.; Morabito, F.C.; Tichmann, C.; Pautasso, G.

    2001-01-01

    The paper addresses the problem of predicting the onset of a disruption on the basis of some known precursors possibly announcing the event. The availability in real time of a large set of diagnostic signals allows us to collectively interpret the data in order to decide whether we are near a disruption or during a normal operation scenario. As a relevant experimental example, a database of disruptive discharges in ASDEX-Upgrade has been analysed in this work. Both Neural Networks (NN's) and Fuzzy Inference Systems (FIS) have been investigated as suitable tools to cope with the prediction problem. The experimental database has been exploited aiming to gain information about the mechanisms which drive the plasma column to a disruption. The proposed processor will operate by implementing a classification of the shot type, and outputting a real number that indicates the time left before the disruption will effectively take place (ttd). (author)

  9. Assigning probability gain for precursors of four large Chinese earthquakes

    Energy Technology Data Exchange (ETDEWEB)

    Cao, T.; Aki, K.

    1983-03-10

    We extend the concept of probability gain associated with a precursor (Aki, 1981) to a set of precursors which may be mutually dependent. Making use of a new formula, we derive a criterion for selecting precursors from a given data set in order to calculate the probability gain. The probabilities per unit time immediately before four large Chinese earthquakes are calculated. They are approximately 0.09, 0.09, 0.07 and 0.08 per day for 1975 Haicheng (M = 7.3), 1976 Tangshan (M = 7.8), 1976 Longling (M = 7.6), and Songpan (M = 7.2) earthquakes, respectively. These results are encouraging because they suggest that the investigated precursory phenomena may have included the complete information for earthquake prediction, at least for the above earthquakes. With this method, the step-by-step approach to prediction used in China may be quantified in terms of the probability of earthquake occurrence. The ln P versus t curve (where P is the probability of earthquake occurrence at time t) shows that ln P does not increase with t linearly but more rapidly as the time of earthquake approaches.

  10. Molecular pathogenesis of precursor lesions of pancreatic ductal adenocarcinoma.

    Science.gov (United States)

    Biankin, Andrew V; Kench, James G; Dijkman, Floriaan P; Biankin, Sandra A; Henshall, Susan M

    2003-02-01

    Precursor lesions are assuming greater importance in the study of pancreatic ductal adenocarcinoma. As pancreatic cancer is almost universally fatal due to late clinical presentation and biological aggressiveness, characterisation of its precursor lesions may create scope for early diagnosis and improved outcome with conventional therapies as well as the development of novel therapeutic and preventative strategies. Pancreatic intraepithelial neoplasia (PanIN) and intraductal papillary mucinous tumours (IPMTs) are thought to be precursor lesions of ductal adenocarcinoma of the pancreas. Recent work has focused on the molecular aberrations associated with these lesions leading to the formulation of a progression model for pancreatic cancer. Progressive histopathological changes along the progression model are associated with aberrations of cell cycle regulatory and growth factor signalling molecules that occur in pancreatic cancer at high frequency and are common to many cancers. Characterisation of these molecular aberrations provides scope for the development of novel diagnostic and treatment strategies that will ultimately impact on the outcome for people who develop pancreatic cancer.

  11. Development of techniques for tagging precursor and essential chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Swansiger, W.A.; Shepodd, T.J. [Sandia National Labs., Livermore, CA (United States); Phillips, M.L.F. [Sandia National Labs., Albuquerque, NM (United States)

    1994-01-01

    The ability to identify the manufacturers and distributors of chemicals seized in raids of illicit drug labs would be of great value in controlling the diversion of these chemicals. We developed a tagging scheme based on the addition of sub-ppM concentrations of various combinations of rare-earth elements to the target chemicals and evaluated a number of techniques for detecting the tags. We developed soluble tags for tagging liquids and selected Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) as the preferred detection technique. We developed insoluble tags for tagging solids and developed methods to analyze them and mix them into solid precursors. We have successfully demonstrated the tagging of several solvents and two of the precursor chemicals used in one of the most popular clandestine methamphetamine syntheses (ephedrine reacting with hydriodic acid/red phosphorus). The tagging scheme is capable of yielding tens of thousands of signatures (using holmium as an internal standard and up to 9 rare-earths at up to 3 concentrations yields 3{sup 9} {minus} 1 = 19,682 signatures) and is applicable to most of the chemicals on the precursor and essential chemicals list. In the concentrations employed, the tags are safe enough to be added to pharmaceuticals and cheap enough to tag tanker loads of chemicals.

  12. Thermogravimetric evaluation of the suitability of precursors for MOCVD

    International Nuclear Information System (INIS)

    Kunte, G V; Shivashankar, S A; Umarji, A M

    2008-01-01

    A method based on the Langmuir equation for the estimation of vapour pressure and enthalpy of sublimation of subliming compounds is described. The variable temperature thermogravimetric/differential thermogravimetric (TG/DTG) curve of benzoic acid is used to arrive at the instrument parameters. Employing these parameters, the vapour pressure–temperature curves are derived for salicylic acid and camphor from their TG/DTG curves. The values match well with vapour pressure data in the literature, obtained by effusion methods. By employing the Clausius–Clapeyron equation, the enthalpy of sublimation could be calculated. Extending the method further, two precursors for metal-organic chemical vapour deposition (MOCVD) of titanium oxide bis-isopropyl bis tert-butyl 2-oxobutanoato titanium, Ti(O i Pr) 2 (tbob) 2 , and bis-oxo-bis-tertbutyl 2-oxobutanoato titanium, [TiO(tbob) 2 ] 2 , have been evaluated. The complex Ti(O i Pr) 2 (tbob) 2 is found to be a more suitable precursor. This approach can be helpful in quickly screening for the suitability of a compound as a CVD precursor

  13. Earthquake prediction the ory and its relation to precursors

    International Nuclear Information System (INIS)

    Negarestani, A.; Setayeshi, S.; Ghannadi-Maragheh, M.; Akasheh, B.

    2001-01-01

    Since we don't have enough knowledge about the Physics of earthquakes. therefore. the study of seismic precursors plays an important role in earthquake prediction. Earthquake prediction is a science which discusses about precursory phenomena during seismogenic process, and then investigates the correlation and association among them and the intrinsic relation between precursors and the seismogenic process. ar the end judges comprehensively the seismic status and finally makes earthquake prediction. There are two ways for predicting earthquake prediction. The first is to study the physics of seismogenic process and to determine the parameters in the process based on the source theories and the second way is to use seismic precursors. In this paper the theory of earthquake is reviewed. We also study theory of earthquake using models of earthquake origin, the relation between seismogenic process and various accompanying precursory phenomena. The earthquake prediction is divided into three categories: long-term, medium-term and short-term. We study seismic anomalous behavior. electric field, crustal deformation, gravity. magnetism of earth. change of groundwater variation. groundwater geochemistry and change of Radon gas emission. Finally, it is concluded the there is a correlation between Radon gas emission and earthquake phenomena. Meanwhile, there are some samples from actual processing in this area

  14. Reduction of precursor decay anomaly in single crystal lithium fluoride

    Science.gov (United States)

    Sano, Yukio

    2000-08-01

    The purpose of this study is to reveal that the precursor decay anomaly in single crystal lithium fluoride is reduced by Sano's decay curve [Y. Sano, J. Appl. Phys. 85, 7616 (1999)], which is much smaller in slope than Asay's decay curve [J. R. Asay, G. R. Fowles, G. E. Duvall, M. H. Miles, and R. F. Tinder, J. Appl. Phys. 43, 2132 (1972)]. To this end, strain, particle, velocity, and stress in a precursor and near the leading edge of the follower changing with time along Sano's decay curve are first analyzed quantitatively. The analysis verified the existence of degenerate contraction waves I and II and a subrarefaction wave R', and the decay process [Y. Sano, J. Appl. Phys. 77, 3746 (1995)] caused in sequence by evolving followers C, I, II, R', Rb. Next, inequalities relating decay rates qualitatively to plastic strain rates at the leading edge of the follower, which are derived using the properties of the followers, are incorporated into the analysis. Calculation results showed that the plastic strain rates were reduced by low decay rates. This indicates that the precursor decay anomaly might be greatly reduced by Sano's decay curve.

  15. Analysis of dependent failures in the ORNL precursor study

    International Nuclear Information System (INIS)

    Ballard, G.M.

    1985-01-01

    The study of dependent failures (or common cause/mode failures) in the safety assessment of potentially hazardous plant is one of the significant areas of uncertainty in performing probabilistic safety studies. One major reason for this uncertainty is that data on dependent failures is apparently not readily available in sufficient quantity to assist in the development and validation of models. The incident reports that were compiled for the ORNL study on Precursors to Severe Core Damage Accidents (NUREG/CR-2497) provide an opportunity to look at the importance of dependent failures in the most significant incidents of recent reactor operations, to look at the success of probabilistic risk assessment (PRA) methods in accounting for the contribution of dependent failures, and to look at the dependent failure incidents with the aim of identifying the most significant problem areas. In this paper an analysis has been made of the incidents compiled in NUREG/CR-2497 and events involving multiple failures which were not independent have been identified. From this analysis it is clear that dependent failures are a very significant contributor to the precursor incidents. The method of enumeration of accident frequency used in NUREG-2497 can be shown to take account of dependent failures and this may be a significant factor contributing to the apparent difference between the precursor accident frequency and typical PRA frequencies

  16. Precursor Wave Emission Enhanced by Weibel Instability in Relativistic Shocks

    Science.gov (United States)

    Iwamoto, Masanori; Amano, Takanobu; Hoshino, Masahiro; Matsumoto, Yosuke

    2018-05-01

    We investigated the precursor wave emission efficiency in magnetized purely perpendicular relativistic shocks in pair plasmas. We extended our previous study to include the dependence of upstream magnetic field orientations. We performed two-dimensional particle-in-cell simulations and focused on two magnetic field orientations: the magnetic field in the simulation plane (i.e., in-plane configuration) and that perpendicular to the simulation plane (i.e., out-of-plane configuration). Our simulations in the in-plane configuration demonstrated that not only extraordinary but also ordinary mode waves are excited. We quantified the emission efficiency as a function of the magnetization parameter σ e and found that the large-amplitude precursor waves are emitted for a wide range of σ e . We found that especially at low σ e , the magnetic field generated by Weibel instability amplifies the ordinary mode wave power. The amplitude is large enough to perturb the upstream plasma, and transverse density filaments are generated as in the case of the out-of-plane configuration investigated in the previous study. We confirmed that our previous conclusion holds regardless of upstream magnetic field orientations with respect to the two-dimensional simulation plane. We discuss the precursor wave emission in three dimensions and the feasibility of wakefield acceleration in relativistic shocks based on our results.

  17. Accident sequence precursor events with age-related contributors

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, G.A.; Kohn, W.E.

    1995-12-31

    The Accident Sequence Precursor (ASP) Program at ORNL analyzed about 14.000 Licensee Event Reports (LERs) filed by US nuclear power plants 1987--1993. There were 193 events identified as precursors to potential severe core accident sequences. These are reported in G/CR-4674. Volumes 7 through 20. Under the NRC Nuclear Plant Aging Research program, the authors evaluated these events to determine the extent to which component aging played a role. Events were selected that involved age-related equipment degradation that initiated an event or contributed to an event sequence. For the 7-year period, ORNL identified 36 events that involved aging degradation as a contributor to an ASP event. Except for 1992, the percentage of age-related events within the total number of ASP events over the 7-year period ({approximately}19%) appears fairly consistent up to 1991. No correlation between plant ape and number of precursor events was found. A summary list of the age-related events is presented in the report.

  18. Spectroscopy Study of Synthetic Forsterite Obtained from Zeolite Precursors

    Directory of Open Access Journals (Sweden)

    Subotić, B.

    2008-02-01

    Full Text Available Important ceramics materials are prepared from aluminosilicate based precursors using novel methods, offering at the same time a better control over many important properties. Forsterite, due to its good refractoriness with melting point at 2163 K, excellent electrical insulation properties even at high temperatures, low dielectric permittivity, thermal expansion and chemical stability, is a material of interest to engineers and designers especially as an active medium for tuneable laser and is also a material of interest to SOFC (Solid oxide fuel cells manufacturers. The aim of this study is to investigate the synthesis of crystalline forsterite using different zeolite precursors previously activated by ball milling. Synthetic forsterite was synthesized from different zeolite precursors and MgO combining highenergy ball milling and thermal treatment of the mixture under determined conditions of time and temperature for each operation. In this research are studied the solid-state phase transformations taking place at temperatures below 1273 K. The obtained products were characterized using different spectroscopy techniques in comparison with surface analysis method and X-ray diffraction.

  19. Laser synthesis of nanostructured ceramics from liquid precursors

    International Nuclear Information System (INIS)

    Wilden, Johannes; Fischer, Georg

    2007-01-01

    The free-form net shape laser synthesis of nanostructured ceramics from liquid precursors enables a residual stress-free production of high temperature resistant ceramic units and components for the use in microsystem engineering. Due to the use of molecular compounded liquid, ceramic precursors the resulting ceramic components show outstanding properties, for example high purity and a nanostructured material design. The use of pulsed lasers enables a defined input of energy required to pyrolyse the precursor material into a crystalline ceramic, so the active volume can be reduced significantly compared to other processes, for example pyrolysis by furnace. In this paper several methods for a further minimization of the active volume are presented. The investigations determined different factors affecting the process. Realizing selective experiments allows a determination of their influencing level and the definition of a working area to produce three-dimensional components with high aspect ratio. By several studies, e.g., scanning electron microscopy, transmission electron microscopy as well as X-ray diffraction analysis, the atomic structure and composition of the created components were analyzed and valued, so the different reaction processes can be described extensively

  20. Distinct functional and temporal requirements for zebrafish Hdac1 during neural crest-derived craniofacial and peripheral neuron development.

    Science.gov (United States)

    Ignatius, Myron S; Unal Eroglu, Arife; Malireddy, Smitha; Gallagher, Glen; Nambiar, Roopa M; Henion, Paul D

    2013-01-01

    The regulation of gene expression is accomplished by both genetic and epigenetic means and is required for the precise control of the development of the neural crest. In hdac1(b382) mutants, craniofacial cartilage development is defective in two distinct ways. First, fewer hoxb3a, dlx2 and dlx3-expressing posterior branchial arch precursors are specified and many of those that are consequently undergo apoptosis. Second, in contrast, normal numbers of progenitors are present in the anterior mandibular and hyoid arches, but chondrocyte precursors fail to terminally differentiate. In the peripheral nervous system, there is a disruption of enteric, DRG and sympathetic neuron differentiation in hdac1(b382) mutants compared to wildtype embryos. Specifically, enteric and DRG-precursors differentiate into neurons in the anterior gut and trunk respectively, while enteric and DRG neurons are rarely present in the posterior gut and tail. Sympathetic neuron precursors are specified in hdac1(b382) mutants and they undergo generic neuronal differentiation but fail to undergo noradrenergic differentiation. Using the HDAC inhibitor TSA, we isolated enzyme activity and temporal requirements for HDAC function that reproduce hdac1(b382) defects in craniofacial and sympathetic neuron development. Our study reveals distinct functional and temporal requirements for zebrafish hdac1 during neural crest-derived craniofacial and peripheral neuron development.

  1. Distinct functional and temporal requirements for zebrafish Hdac1 during neural crest-derived craniofacial and peripheral neuron development.

    Directory of Open Access Journals (Sweden)

    Myron S Ignatius

    Full Text Available The regulation of gene expression is accomplished by both genetic and epigenetic means and is required for the precise control of the development of the neural crest. In hdac1(b382 mutants, craniofacial cartilage development is defective in two distinct ways. First, fewer hoxb3a, dlx2 and dlx3-expressing posterior branchial arch precursors are specified and many of those that are consequently undergo apoptosis. Second, in contrast, normal numbers of progenitors are present in the anterior mandibular and hyoid arches, but chondrocyte precursors fail to terminally differentiate. In the peripheral nervous system, there is a disruption of enteric, DRG and sympathetic neuron differentiation in hdac1(b382 mutants compared to wildtype embryos. Specifically, enteric and DRG-precursors differentiate into neurons in the anterior gut and trunk respectively, while enteric and DRG neurons are rarely present in the posterior gut and tail. Sympathetic neuron precursors are specified in hdac1(b382 mutants and they undergo generic neuronal differentiation but fail to undergo noradrenergic differentiation. Using the HDAC inhibitor TSA, we isolated enzyme activity and temporal requirements for HDAC function that reproduce hdac1(b382 defects in craniofacial and sympathetic neuron development. Our study reveals distinct functional and temporal requirements for zebrafish hdac1 during neural crest-derived craniofacial and peripheral neuron development.

  2. A possible island of beta-delayed neutron precursors in heavy nucleus region

    International Nuclear Information System (INIS)

    Zhang Li

    1991-01-01

    The possible Beta-Delayed neutron precursors in the elements Tl, Hg, and Au were predicted following a systematic research on the known Beta-Delayed neutron precursors. The masses of the unknown nuclei and neutron emission probabilities were calculated

  3. Versatile High-Performance Regenerated Cellulose Membranes Prepared using Trimethylsilyl Cellulose as a Precursor

    KAUST Repository

    Puspasari, Tiara

    2018-01-01

    (TMSC), a highly soluble cellulose derivative, as a precursor for the fabrication of cellulose thin film composite membranes. TMSC is an attractive precursor to assemble thin cellulose films with good deposition behavior and film morphology; cumbersome

  4. Neural correlates of hate.

    Directory of Open Access Journals (Sweden)

    Semir Zeki

    Full Text Available In this work, we address an important but unexplored topic, namely the neural correlates of hate. In a block-design fMRI study, we scanned 17 normal human subjects while they viewed the face of a person they hated and also faces of acquaintances for whom they had neutral feelings. A hate score was obtained for the object of hate for each subject and this was used as a covariate in a between-subject random effects analysis. Viewing a hated face resulted in increased activity in the medial frontal gyrus, right putamen, bilaterally in premotor cortex, in the frontal pole and bilaterally in the medial insula. We also found three areas where activation correlated linearly with the declared level of hatred, the right insula, right premotor cortex and the right fronto-medial gyrus. One area of deactivation was found in the right superior frontal gyrus. The study thus shows that there is a unique pattern of activity in the brain in the context of hate. Though distinct from the pattern of activity that correlates with romantic love, this pattern nevertheless shares two areas with the latter, namely the putamen and the insula.

  5. neural control system

    International Nuclear Information System (INIS)

    Elshazly, A.A.E.

    2002-01-01

    Automatic power stabilization control is the desired objective for any reactor operation , especially, nuclear power plants. A major problem in this area is inevitable gap between a real plant ant the theory of conventional analysis and the synthesis of linear time invariant systems. in particular, the trajectory tracking control of a nonlinear plant is a class of problems in which the classical linear transfer function methods break down because no transfer function can represent the system over the entire operating region . there is a considerable amount of research on the model-inverse approach using feedback linearization technique. however, this method requires a prices plant model to implement the exact linearizing feedback, for nuclear reactor systems, this approach is not an easy task because of the uncertainty in the plant parameters and un-measurable state variables . therefore, artificial neural network (ANN) is used either in self-tuning control or in improving the conventional rule-based exper system.the main objective of this thesis is to suggest an ANN, based self-learning controller structure . this method is capable of on-line reinforcement learning and control for a nuclear reactor with a totally unknown dynamics model. previously, researches are based on back- propagation algorithm . back -propagation (BP), fast back -propagation (FBP), and levenberg-marquardt (LM), algorithms are discussed and compared for reinforcement learning. it is found that, LM algorithm is quite superior

  6. Influence of neural adaptation on dynamics and equilibrium state of neural activities in a ring neural network

    Science.gov (United States)

    Takiyama, Ken

    2017-12-01

    How neural adaptation affects neural information processing (i.e. the dynamics and equilibrium state of neural activities) is a central question in computational neuroscience. In my previous works, I analytically clarified the dynamics and equilibrium state of neural activities in a ring-type neural network model that is widely used to model the visual cortex, motor cortex, and several other brain regions. The neural dynamics and the equilibrium state in the neural network model corresponded to a Bayesian computation and statistically optimal multiple information integration, respectively, under a biologically inspired condition. These results were revealed in an analytically tractable manner; however, adaptation effects were not considered. Here, I analytically reveal how the dynamics and equilibrium state of neural activities in a ring neural network are influenced by spike-frequency adaptation (SFA). SFA is an adaptation that causes gradual inhibition of neural activity when a sustained stimulus is applied, and the strength of this inhibition depends on neural activities. I reveal that SFA plays three roles: (1) SFA amplifies the influence of external input in neural dynamics; (2) SFA allows the history of the external input to affect neural dynamics; and (3) the equilibrium state corresponds to the statistically optimal multiple information integration independent of the existence of SFA. In addition, the equilibrium state in a ring neural network model corresponds to the statistically optimal integration of multiple information sources under biologically inspired conditions, independent of the existence of SFA.

  7. Functional Analysis of Precursors for Serious Problem Behavior and Related Intervention

    Science.gov (United States)

    Langdon, Nancy A.; Carr, Edward G.; Owen-DeSchryver, Jamie S.

    2008-01-01

    Precursor behaviors are innocuous behaviors that reliably precede the occurrence of problem behavior. Intervention efforts applied to precursors might prevent the occurrence of severe problem behavior. We examined the relationship between precursor behavior and problem behavior in three individuals with developmental disabilities. First, a…

  8. Fractional Hopfield Neural Networks: Fractional Dynamic Associative Recurrent Neural Networks.

    Science.gov (United States)

    Pu, Yi-Fei; Yi, Zhang; Zhou, Ji-Liu

    2017-10-01

    This paper mainly discusses a novel conceptual framework: fractional Hopfield neural networks (FHNN). As is commonly known, fractional calculus has been incorporated into artificial neural networks, mainly because of its long-term memory and nonlocality. Some researchers have made interesting attempts at fractional neural networks and gained competitive advantages over integer-order neural networks. Therefore, it is naturally makes one ponder how to generalize the first-order Hopfield neural networks to the fractional-order ones, and how to implement FHNN by means of fractional calculus. We propose to introduce a novel mathematical method: fractional calculus to implement FHNN. First, we implement fractor in the form of an analog circuit. Second, we implement FHNN by utilizing fractor and the fractional steepest descent approach, construct its Lyapunov function, and further analyze its attractors. Third, we perform experiments to analyze the stability and convergence of FHNN, and further discuss its applications to the defense against chip cloning attacks for anticounterfeiting. The main contribution of our work is to propose FHNN in the form of an analog circuit by utilizing a fractor and the fractional steepest descent approach, construct its Lyapunov function, prove its Lyapunov stability, analyze its attractors, and apply FHNN to the defense against chip cloning attacks for anticounterfeiting. A significant advantage of FHNN is that its attractors essentially relate to the neuron's fractional order. FHNN possesses the fractional-order-stability and fractional-order-sensitivity characteristics.

  9. c-Myc Enhances Sonic Hedgehog-Induced Medulloblastoma Formation from Nestin-Expressing Neural Progenitors in Mice

    Directory of Open Access Journals (Sweden)

    Ganesh Rao

    2003-05-01

    Full Text Available Medulloblastomas are malignant brain tumors that arise in the cerebella of children. The presumed cellsof-origin are undifferentiated precursors of granule neurons that occupy the external granule layer (EGL of the developing cerebellum. The overexpression of proteins that normally stimulate proliferation of neural progenitor cells may initiate medulloblastoma formation. Two known mitogens for neural progenitors are the c-Myc oncoprotein and Sonic hedgehog (Shh, a crucial determinant of embryonic pattern formation in the central nervous system. We modeled the ability of c-Myc and Shh to induce medulloblastoma in mice using the RCAS/tv-a system, which allows postnatal gene transfer and expression in a cell type-specific manner. We targeted the expression of Shh and c-Myc to nestin-expressing neural progenitor cells by injecting replication-competent ALV splice acceptor (RCAS vectors into the cerebella of newborn mice. Following injection with RCAS-Shh alone, 3/32 (9% mice developed medulloblastomas and 5/32 showed multifocal hyperproliferation of the EGL, possibly a precursor stage of medulloblastoma. Following injection with RCAS-Shh plus RCAS-Myc, 9/39 (23% mice developed medulloblastomas. We conclude that nestin-expressing neural progenitors, present in the cerebellum at birth, can act as the cells-of-origin for medulloblastoma, and that c-Myc cooperates with Shh to enhance tumorigenicity.

  10. Transplantation of oligodendrocyte precursors and sonic hedgehog results in improved function and white matter sparing in the spinal cords of adult rats after contusion.

    Science.gov (United States)

    Bambakidis, Nicholas C; Miller, Robert H

    2004-01-01

    A substantial cause of neurological disability in spinal cord injury is oligodendrocyte death leading to demyelination and axonal degeneration. Rescuing oligodendrocytes and preserving myelin is expected to result in significant improvement in functional outcome after spinal cord injury. Although previous investigators have used cellular transplantation of xenografted pluripotent embryonic stem cells and observed improved functional outcome, these transplants have required steroid administration and only a minority of these cells develop into oligodendrocytes. The objective of the present study was to determine whether allografts of oligodendrocyte precursors transplanted into an area of incomplete spinal cord contusion would improve behavioral and electrophysiological measures of spinal cord function. Additional treatment incorporated the use of the glycoprotein molecule Sonic hedgehog (Shh), which has been shown to play a critical role in oligodendroglial development and induce proliferation of endogenous neural precursors after spinal cord injury. Laboratory study. Moderate spinal cord contusion injury was produced in 39 adult rats at T9-T10. Ten animals died during the course of the study. Nine rats served as contusion controls (Group 1). Six rats were treated with oligodendrocyte precursor transplantation 5 days after injury (Group 2). The transplanted cells were isolated from newborn rat pups using immunopanning techniques. Another eight rats received an injection of recombinant Shh along with the oligodendrocyte precursors (Group 3), while six more rats were treated with Shh alone (Group 4). Eight additional rats received only T9 laminectomies to serve as noninjured controls (Group 0). Animals were followed for 28 days. After an initial complete hindlimb paralysis, rats of all groups receiving a contusive injury recovered substantial function within 1 week. By 28 days, rats in Groups 2 and 3 scored 4.7 and 5.8 points better on the Basso, Beattie, Bresnahan

  11. Neural network regulation driven by autonomous neural firings

    Science.gov (United States)

    Cho, Myoung Won

    2016-07-01

    Biological neurons naturally fire spontaneously due to the existence of a noisy current. Such autonomous firings may provide a driving force for network formation because synaptic connections can be modified due to neural firings. Here, we study the effect of autonomous firings on network formation. For the temporally asymmetric Hebbian learning, bidirectional connections lose their balance easily and become unidirectional ones. Defining the difference between reciprocal connections as new variables, we could express the learning dynamics as if Ising model spins interact with each other in magnetism. We present a theoretical method to estimate the interaction between the new variables in a neural system. We apply the method to some network systems and find some tendencies of autonomous neural network regulation.

  12. Possibility to study ionospheric earthquakes precursors using CubeSats

    Science.gov (United States)

    Korepanov, Valery; Lappas, Vaios

    It is generally accepted that the earthquakes (EQ) are the most dangerous natural phenomena leading to the multiple losses in human lives and economics. The space observations must be included into the global chain of the EQ precursors monitoring at least as the initial warning to pay greater attention to the ground segment data. As the common opinion agrees, only in combination of multiple observation sites and set of monitored parameters the further progress at the way to raise EQ precursors detection probability may be obtained. There is necessary to answer two important questions before to plan any experiment to study ionospheric precursors of EQ. First one - whether the variations in the ionosphere definitely connected with the EQ preparation process do exist, and the second one - if they do, whether using these signals the precursors of EQ can be reliably identified and used for, if not prediction, then for the warning that the EQ in the given area approaches. The first successful mission dedicated to this problem solution was DEMETER (in orbit during more than 6 years from June 2004 until December 2010). The statistics of this study is impressive: altogether, about 9000 EQs with magnitude larger than M = 5.0 and depth lower than 40 km occurred all over the world during the analyzed period. In the result, the conclusion made there suggests that, obviously, there are real perturbations in the ionosphere connected with the seismic activity, but they are rather weak and at the present stage of data processing may be revealed only with the help of statistical analysis. To realize the study of ionospheric precursors, first it is imperative to clarify the mechanism of energy transfer along the chain “lithosphere-atmosphere-ionosphere”. Many hypotheses of such a mechanism exist, from which the mostly supported are fair weather currents (FWC) and atmospheric gravity waves (AGW), both of which have their pros and contras. The following minimal set of physical

  13. Precursors to language: Social cognition and pragmatic inference in primates.

    Science.gov (United States)

    Seyfarth, Robert M; Cheney, Dorothy L

    2017-02-01

    Despite their differences, human language and the vocal communication of nonhuman primates share many features. Both constitute forms of coordinated activity, rely on many shared neural mechanisms, and involve discrete, combinatorial cognition that includes rich pragmatic inference. These common features suggest that during evolution the ancestors of all modern primates faced similar social problems and responded with similar systems of communication and cognition. When language later evolved from this common foundation, many of its distinctive features were already present.

  14. Accident Precursor Analysis and Management: Reducing Technological Risk Through Diligence

    Science.gov (United States)

    Phimister, James R. (Editor); Bier, Vicki M. (Editor); Kunreuther, Howard C. (Editor)

    2004-01-01

    Almost every year there is at least one technological disaster that highlights the challenge of managing technological risk. On February 1, 2003, the space shuttle Columbia and her crew were lost during reentry into the atmosphere. In the summer of 2003, there was a blackout that left millions of people in the northeast United States without electricity. Forensic analyses, congressional hearings, investigations by scientific boards and panels, and journalistic and academic research have yielded a wealth of information about the events that led up to each disaster, and questions have arisen. Why were the events that led to the accident not recognized as harbingers? Why were risk-reducing steps not taken? This line of questioning is based on the assumption that signals before an accident can and should be recognized. To examine the validity of this assumption, the National Academy of Engineering (NAE) undertook the Accident Precursors Project in February 2003. The project was overseen by a committee of experts from the safety and risk-sciences communities. Rather than examining a single accident or incident, the committee decided to investigate how different organizations anticipate and assess the likelihood of accidents from accident precursors. The project culminated in a workshop held in Washington, D.C., in July 2003. This report includes the papers presented at the workshop, as well as findings and recommendations based on the workshop results and committee discussions. The papers describe precursor strategies in aviation, the chemical industry, health care, nuclear power and security operations. In addition to current practices, they also address some areas for future research.

  15. Selective Disparity of Ordinary Chondritic Precursors in Micrometeorite Flux

    Science.gov (United States)

    Rudraswami, N. G.; Fernandes, D.; Naik, A. K.; Shyam Prasad, M.; Carrillo-Sánchez, J. D.; Plane, J. M. C.; Feng, W.; Taylor, S.

    2018-01-01

    All known extraterrestrial dust (micrometeoroids) entering the Earth’s atmosphere is anticipated to have a significant contribution from ordinary chondritic precursors, as seen in meteorites, but this is an apparent contradiction that needs to be addressed. Ordinary chondrites represent a minor contribution to the overall meteor influx compared to carbonaceous chondrites, which are largely dominated by CI and/or CM chondrites. However, the near-Earth asteroid population presents a scenario with sufficient scope for generation of dust-sized debris from ordinary chondritic sources. The bulk chemical composition of 3255 micrometeorites (MMs) collected from Antarctica and deep-sea sediments has shown Mg/Si largely dominated by carbonaceous chondrites, and less than 10% having ordinary chondritic precursors. The chemical ablation model is combined with different initial chondritic compositions (CI, CV, L, LL, H), and the results clearly indicate that high-density (≥2.8 g cm‑3) precursors, such as CV and ordinary chondrites in the size range 100–700 μm and zenith angle 0°–70°, ablate at much faster rates and lose their identity even before reaching the Earth’s surface and hence are under-represented in our collections. Moreover, their ability to survive as MMs remains grim for high-velocity micrometeoroids (>16 km s‑1). The elemental ratio for CV and ordinary chondrites are also similar to each other irrespective of the difference in the initial chemical composition. In conclusion, MMs belonging to ordinary chondritic precursors’ concentrations may not be insignificant in thermosphere, as they are found on Earth’s surface.

  16. Molecular analysis of precursor lesions in familial pancreatic cancer.

    Directory of Open Access Journals (Sweden)

    Tatjana Crnogorac-Jurcevic

    Full Text Available With less than a 5% survival rate pancreatic adenocarcinoma (PDAC is almost uniformly lethal. In order to make a significant impact on survival of patients with this malignancy, it is necessary to diagnose the disease early, when curative surgery is still possible. Detailed knowledge of the natural history of the disease and molecular events leading to its progression is therefore critical.We have analysed the precursor lesions, PanINs, from prophylactic pancreatectomy specimens of patients from four different kindreds with high risk of familial pancreatic cancer who were treated for histologically proven PanIN-2/3. Thus, the material was procured before pancreatic cancer has developed, rather than from PanINs in a tissue field that already contains cancer. Genome-wide transcriptional profiling using such unique specimens was performed. Bulk frozen sections displaying the most extensive but not microdissected PanIN-2/3 lesions were used in order to obtain the holistic view of both the precursor lesions and their microenvironment. A panel of 76 commonly dysregulated genes that underlie neoplastic progression from normal pancreas to PanINs and PDAC were identified. In addition to shared genes some differences between the PanINs of individual families as well as between the PanINs and PDACs were also seen. This was particularly pronounced in the stromal and immune responses.Our comprehensive analysis of precursor lesions without the invasive component provides the definitive molecular proof that PanIN lesions beget cancer from a molecular standpoint. We demonstrate the need for accumulation of transcriptomic changes during the progression of PanIN to PDAC, both in the epithelium and in the surrounding stroma. An identified 76-gene signature of PDAC progression presents a rich candidate pool for the development of early diagnostic and/or surveillance markers as well as potential novel preventive/therapeutic targets for both familial and sporadic

  17. Cell adhesion signaling regulates RANK expression in osteoclast precursors.

    Directory of Open Access Journals (Sweden)

    Ayako Mochizuki

    Full Text Available Cells with monocyte/macrophage lineage expressing receptor activator of NF-κB (RANK differentiate into osteoclasts following stimulation with the RANK ligand (RANKL. Cell adhesion signaling is also required for osteoclast differentiation from precursors. However, details of the mechanism by which cell adhesion signals induce osteoclast differentiation have not been fully elucidated. To investigate the participation of cell adhesion signaling in osteoclast differentiation, mouse bone marrow-derived macrophages (BMMs were used as osteoclast precursors, and cultured on either plastic cell culture dishes (adherent condition or the top surface of semisolid methylcellulose gel loaded in culture tubes (non-adherent condition. BMMs cultured under the adherent condition differentiated into osteoclasts in response to RANKL stimulation. However, under the non-adherent condition, the efficiency of osteoclast differentiation was markedly reduced even in the presence of RANKL. These BMMs retained macrophage characteristics including phagocytic function and gene expression profile. Lipopolysaccharide (LPS and tumor necrosis factor -αTNF-α activated the NF-κB-mediated signaling pathways under both the adherent and non-adherent conditions, while RANKL activated the pathways only under the adherent condition. BMMs highly expressed RANK mRNA and protein under the adherent condition as compared to the non-adherent condition. Also, BMMs transferred from the adherent to non-adherent condition showed downregulated RANK expression within 24 hours. In contrast, transferring those from the non-adherent to adherent condition significantly increased the level of RANK expression. Moreover, interruption of cell adhesion signaling by echistatin, an RGD-containing disintegrin, decreased RANK expression in BMMs, while forced expression of either RANK or TNFR-associated factor 6 (TRAF6 in BMMs induced their differentiation into osteoclasts even under the non

  18. Isotopic and geochemical precursors of earthquakes and volcanic eruptions

    International Nuclear Information System (INIS)

    1993-11-01

    Radon 222 seems to be one of the most promising precursors and is the tracer for which more data are available: according to statistics elaborated in China, 70% of earthquakes are preceded by radon anomalies detectable in soil, air and/or in groundwater. Also other changes of the fluid chemical composition and variations of 3 He/ 4 He, 2 H/ 1 H, 13 C/ 12 C, 18 O/ 16 O isotopic ratios have been detected. Among these indicators one can mention variations in concentration and/or isotopic ratios of hydrogen, helium, carbon, oxygen, neon, radon, radium and uranium. Refs, figs, tabs

  19. The wireless networking system of Earthquake precursor mobile field observation

    Science.gov (United States)

    Wang, C.; Teng, Y.; Wang, X.; Fan, X.; Wang, X.

    2012-12-01

    The mobile field observation network could be real-time, reliably record and transmit large amounts of data, strengthen the physical signal observations in specific regions and specific period, it can improve the monitoring capacity and abnormal tracking capability. According to the features of scatter everywhere, a large number of current earthquake precursor observation measuring points, networking technology is based on wireless broadband accessing McWILL system, the communication system of earthquake precursor mobile field observation would real-time, reliably transmit large amounts of data to the monitoring center from measuring points through the connection about equipment and wireless accessing system, broadband wireless access system and precursor mobile observation management center system, thereby implementing remote instrument monitoring and data transmition. At present, the earthquake precursor field mobile observation network technology has been applied to fluxgate magnetometer array geomagnetic observations of Tianzhu, Xichang,and Xinjiang, it can be real-time monitoring the working status of the observational instruments of large area laid after the last two or three years, large scale field operation. Therefore, it can get geomagnetic field data of the local refinement regions and provide high-quality observational data for impending earthquake tracking forecast. Although, wireless networking technology is very suitable for mobile field observation with the features of simple, flexible networking etc, it also has the phenomenon of packet loss etc when transmitting a large number of observational data due to the wireless relatively weak signal and narrow bandwidth. In view of high sampling rate instruments, this project uses data compression and effectively solves the problem of data transmission packet loss; Control commands, status data and observational data transmission use different priorities and means, which control the packet loss rate within

  20. Ionospheric parameters as the precursors of disturbed geomagnetic conditions

    Science.gov (United States)

    Blagoveshchensky, D. V.; Sergeeva, M. A.; Kozlovsky, A.

    2017-12-01

    Geomagnetic storms and substorms are the principal elements of the disturbed Space Weather conditions. The aim of the study was to reveal the ionospheric precursors that can be used to forecast geomagnetic disturbance beginning. To study the ionospheric processes before, during and after magnetic storms and substorms data from Sodankylä Geophysical Observatory was used (geomagnetic coordinates: 64.1oN, 119.2oE). In earlier works the Main Effect (ME) was revealed for substorms. It consists of the following steps: (a) the increase of critical frequency foF2 from its quiet median before and during the substorm growth phase, four-five hours before To moment that is the moment of the expansion phase onset, (b) the foF2 decrease to the level lower than its median just after To and until Te that is the moment of the end of the expansion phase, (c) the issue ;a; repeated during the recovery phase (d) two bell-shape spikes in the cutoff frequency values foEs: first spike occurs three hours before To, second spike - during the expansion phase within the interval between To and Te. In the present work it is shown that ME manifestations can be used as precursors of magnetic substorms at high-latitudes (geomagnetic latitudes 50oN-65oN). In particular, the foF2 growth some hours before To can be used as a precursor of substorm development. The first foEs bell-shaped spike also can be used for short-term forecasting, two-three hours in advance of a substorm. Furthermore, the storms between 2008 and 2012 were studied. It was revealed that the similar ME also takes place in the case of magnetic storms but within the different time scale. More specifically, the first ME maximum in foF2 values occurs one-two days before the storm beginning and can be used as its precursor. In addition, the foEs spike takes place approximately ten hours before a storm and also can be used for the prediction of the storm beginning.

  1. Multifunctional Silica Nanoparticles Modified via Silylated-Decaborate Precursors

    Directory of Open Access Journals (Sweden)

    Fatima Abi-Ghaida

    2015-01-01

    Full Text Available A new class of multifunctional silica nanoparticles carrying boron clusters (10-vertex closo-decaborate and incorporating luminescent centers (fluorescein has been developed as potential probes/carriers for potential application in boron neutron capture therapy (BNCT. These silica nanoparticles were charged in situ with silylated-fluorescein fluorophores via the Stöber method and their surface was further functionalized with decaborate-triethoxysilane precursors. The resulting decaborate dye-doped silica nanoparticles were characterized by TEM, solid state NMR, DLS, nitrogen sorption, elemental analysis, and fluorescence spectroscopy.

  2. Spatially correlated disorder in striped precursor magnetic modulations

    International Nuclear Information System (INIS)

    Porta, Marcel; Castan, Teresa; LLoveras, Pol; Planes, Antoni; Saxena, Avadh

    2007-01-01

    We use a Ginzburg-Landau model that includes long-range dipolar interactions and spatially correlated quenched-in disorder coupled to the local magnetization to study the properties of the precursor magnetic modulations as a function of the characteristics of the disorder. We find that although the modulation pattern is very robust and does not depend on details of the pair correlation function G(r), the scaling behaviour of the characteristic length of the striped magnetic modulations depends on the behaviour of G(r) for small values of r

  3. Synthesis of carbon nanotubes using natural carbon precursor: Castor oil

    Science.gov (United States)

    Raziah, A. Z.; Junizah, A. R.; Saifuddin, N.

    2012-09-01

    Castor oil has long been an article of commerce due to its versatility as it is widely used as a starting material for many industrial chemical products because of its unique structure. In this study, carbon nanotubes has been synthesized by thermal decomposition of castor oil in nitrogen atmosphere at 300-400δC using custom-made microwave processing unit. The precursor material was catalyzed by iron clusters originating from the addition of ferrocene. The morphology and characterization of the CNTs were studied and discussed by transmission electron microscopy (TEM).

  4. Graphene nanoribbons synthesized from molecular precursor polymerization on Au(110)

    Energy Technology Data Exchange (ETDEWEB)

    Massimi, Lorenzo; Ourdjini, Oualid; Della Pia, Ada; Mariani, Carlo; Betti, Maria Grazia [Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 2, I - 00185 Roma (Italy); Cavaliere, Emanuele; Gavioli, Luca [i-LAMP & Dipartimento di Matematica e Fisica, Università Cattolica, 25121 Brescia (Italy)

    2015-06-23

    A spectroscopic study of 10,10-dibromo-9,9 bianthracene (DBBA) molecules deposited on the Au(110) surface is presented, by means of ultraviolet and X-ray photoemission, and X-ray absorption spectroscopy. Through a thermally activated procedure, these molecular precursors polymerize and eventually form graphene nanoribbons (GNRs) with atomically controlled shape and width, very important building blocks for several technological applications. The GNRs observed by scanning tunneling microscopy (STM) appear as short segments on top of the gold surface reconstruction, pointing out the delicate balance among surface diffusion and surface corrugation in their synthesis on the Au(110) surface.

  5. Aroma Precursors in Grapes and Wine: Flavor Release during Wine Production and Consumption.

    Science.gov (United States)

    Parker, Mango; Capone, Dimitra L; Francis, I Leigh; Herderich, Markus J

    2018-03-14

    Pioneering investigations into precursors of fruity and floral flavors established the importance of terpenoid and C 13 -norisoprenoid glycosides to the flavor of aromatic wines. Nowadays flavor precursors in grapes and wine are known to be structurally diverse, encompassing glycosides, amino acid conjugates, odorless volatiles, hydroxycinnamic acids, and many others. Flavor precursors mainly originate in the grape berry but also from oak or other materials involved in winemaking. Flavors are released from precursors during crushing and subsequent production steps by enzymatic and nonenzymatic transformations, via microbial glycosidases, esterases, C-S lyases, and decarboxylases, and through acid-catalyzed hydrolysis and chemical rearrangements. Flavors can also be liberated from glycosides and amino acid conjugates by oral microbiota. Hence, it is increasingly likely that flavor precursors contribute to retronasal aroma formation through in-mouth release during consumption, prompting a shift in focus from identifying aroma precursors in grapes to understanding aroma precursors present in bottled wine.

  6. Differentiation of retinal ganglion cells and photoreceptor precursors from mouse induced pluripotent stem cells carrying an Atoh7/Math5 lineage reporter.

    Directory of Open Access Journals (Sweden)

    Bin-Bin Xie

    Full Text Available The neural retina is a critical component of the visual system, which provides the majority of sensory input in humans. Various retinal degenerative diseases can result in the permanent loss of retinal neurons, especially the light-sensing photoreceptors and the centrally projecting retinal ganglion cells (RGCs. The replenishment of lost RGCs and the repair of optic nerve damage are particularly challenging, as both RGC specification and their subsequent axonal growth and projection involve complex and precise regulation. To explore the developmental potential of pluripotent stem cell-derived neural progenitors, we have established mouse iPS cells that allow cell lineage tracing of progenitors that have expressed Atoh7/Math5, a bHLH transcription factor required for RGC production. These Atoh7 lineage reporter iPS cells encode Cre to replace one copy of the endogenous Atoh7 gene and a Cre-dependent YFP reporter in the ROSA locus. In addition, they express pluripotent markers and are capable of generating teratomas in vivo. Under anterior neural induction and neurogenic conditions in vitro, the Atoh7-Cre/ROSA-YFP iPS cells differentiate into neurons that co-express various RGC markers and YFP, indicating that these neurons are derived from Atoh7-expressing progenitors. Consistent with previous in vivo cell lineage studies, the Atoh7-Cre/ROSA-YFP iPS cells also give rise to a subset of Crx-positive photoreceptor precursors. Furthermore, inhibition of Notch signaling in the iPSC cultures results in a significant increase of YFP-positive RGCs and photoreceptor precursors. Together, these results show that Atoh7-Cre/ROSA-YFP iPS cells can be used to monitor the development and survival of RGCs and photoreceptors from pluripotent stem cells.

  7. Neural networks and statistical learning

    CERN Document Server

    Du, Ke-Lin

    2014-01-01

    Providing a broad but in-depth introduction to neural network and machine learning in a statistical framework, this book provides a single, comprehensive resource for study and further research. All the major popular neural network models and statistical learning approaches are covered with examples and exercises in every chapter to develop a practical working understanding of the content. Each of the twenty-five chapters includes state-of-the-art descriptions and important research results on the respective topics. The broad coverage includes the multilayer perceptron, the Hopfield network, associative memory models, clustering models and algorithms, the radial basis function network, recurrent neural networks, principal component analysis, nonnegative matrix factorization, independent component analysis, discriminant analysis, support vector machines, kernel methods, reinforcement learning, probabilistic and Bayesian networks, data fusion and ensemble learning, fuzzy sets and logic, neurofuzzy models, hardw...

  8. Neural networks in signal processing

    International Nuclear Information System (INIS)

    Govil, R.

    2000-01-01

    Nuclear Engineering has matured during the last decade. In research and design, control, supervision, maintenance and production, mathematical models and theories are used extensively. In all such applications signal processing is embedded in the process. Artificial Neural Networks (ANN), because of their nonlinear, adaptive nature are well suited to such applications where the classical assumptions of linearity and second order Gaussian noise statistics cannot be made. ANN's can be treated as nonparametric techniques, which can model an underlying process from example data. They can also adopt their model parameters to statistical change with time. Algorithms in the framework of Neural Networks in Signal processing have found new applications potentials in the field of Nuclear Engineering. This paper reviews the fundamentals of Neural Networks in signal processing and their applications in tasks such as recognition/identification and control. The topics covered include dynamic modeling, model based ANN's, statistical learning, eigen structure based processing and generalization structures. (orig.)

  9. Principles of neural information processing

    CERN Document Server

    Seelen, Werner v

    2016-01-01

    In this fundamental book the authors devise a framework that describes the working of the brain as a whole. It presents a comprehensive introduction to the principles of Neural Information Processing as well as recent and authoritative research. The books´ guiding principles are the main purpose of neural activity, namely, to organize behavior to ensure survival, as well as the understanding of the evolutionary genesis of the brain. Among the developed principles and strategies belong self-organization of neural systems, flexibility, the active interpretation of the world by means of construction and prediction as well as their embedding into the world, all of which form the framework of the presented description. Since, in brains, their partial self-organization, the lifelong adaptation and their use of various methods of processing incoming information are all interconnected, the authors have chosen not only neurobiology and evolution theory as a basis for the elaboration of such a framework, but also syst...

  10. Pericytes and endothelial precursor cells: cellular interactions and contributions to malignancy.

    Science.gov (United States)

    Bagley, Rebecca G; Weber, William; Rouleau, Cecile; Teicher, Beverly A

    2005-11-01

    Tumor vasculature is irregular, abnormal, and essential for tumor growth. Pericytes and endothelial precursor cells (EPC) contribute to the formation of blood vessels under angiogenic conditions. As primary cells in culture, pericytes and EPC share many properties such as tube/network formation and response to kinase inhibitors selective for angiogenic pathways. Expression of cell surface proteins including platelet-derived growth factor receptor, vascular cell adhesion molecule, intercellular adhesion molecule, CD105, desmin, and neural growth proteoglycan 2 was similar between pericytes and EPC, whereas expression of P1H12 and lymphocyte function-associated antigen-1 clearly differentiates the cell types. Further distinction was observed in the molecular profiles for expression of angiogenic genes. Pericytes or EPC enhanced the invasion of MDA-MB-231 breast cancer cells in a coculture assay system. The s.c. coinjection of live pericytes or EPC along with MDA-MB-231 cells resulted in an increased rate of tumor growth compared with coinjection of irradiated pericytes or EPC. Microvessel density analysis indicated there was no difference in MDA-MB-231 tumors with or without EPC or pericytes. However, immunohistochemical staining of vasculature suggested that EPC and pericytes may stabilize or normalize vasculature rather than initiate vasculogenesis. In addition, tumors arising from the coinjection of EPC and cancer cells were more likely to develop lymphatic vessels. These results support the notion that pericytes and EPC contribute to malignancy and that these cell types can be useful as cell-based models for tumor vascular development and selection of agents that may provide therapeutic benefit.

  11. Sonic Hedgehog Signaling Drives Mitochondrial Fragmentation by Suppressing Mitofusins in Cerebellar Granule Neuron Precursors and Medulloblastoma.

    Science.gov (United States)

    Malhotra, Anshu; Dey, Abhinav; Prasad, Niyathi; Kenney, Anna Marie

    2016-01-01

    Sonic hedgehog (Shh) signaling is closely coupled with bioenergetics of medulloblastoma, the most common malignant pediatric brain tumor. Shh-associated medulloblastoma arises from cerebellar granule neuron precursors (CGNP), a neural progenitor whose developmental expansion requires signaling by Shh, a ligand secreted by the neighboring Purkinje neurons. Previous observations show that Shh signaling inhibits fatty acid oxidation although driving increased fatty acid synthesis. Proliferating CGNPs and mouse Shh medulloblastomas feature high levels of glycolytic enzymes in vivo and in vitro. Because both of these metabolic processes are closely linked to mitochondrial bioenergetics, the role of Shh signaling in mitochondrial biogenesis was investigated. This report uncovers a surprising decrease in mitochondrial membrane potential (MMP) and overall ATP production in CGNPs exposed to Shh, consistent with increased glycolysis resulting in high intracellular acidity, leading to mitochondrial fragmentation. Ultrastructural examination of mitochondria revealed a spherical shape in Shh-treated cells, in contrast to the elongated appearance in vehicle-treated postmitotic cells. Expression of mitofusin 1 and 2 was reduced in these cells, although their ectopic expression restored the MMP to the nonproliferating state and the morphology to a fused, interconnected state. Mouse Shh medulloblastoma cells featured drastically impaired mitochondrial morphology, restoration of which by ectopic mitofusin expression was also associated with a decrease in the expression of Cyclin D2 protein, a marker for proliferation. This report exposes a novel role for Shh in regulating mitochondrial dynamics and rescue of the metabolic profile of tumor cells to that of nontransformed, nonproliferating cells and represents a potential avenue for development of medulloblastoma therapeutics. ©2015 American Association for Cancer Research.

  12. Perfluoroalkyl Acids (PFAAs) and Selected Precursors in the Baltic Sea Environment: Do Precursors Play a Role in Food Web Accumulation of PFAAs?

    Science.gov (United States)

    Gebbink, Wouter A; Bignert, Anders; Berger, Urs

    2016-06-21

    The present study examined the presence of perfluoroalkyl acids (PFAAs) and selected precursors in the Baltic Sea abiotic environment and guillemot food web, and investigated the relative importance of precursors in food web accumulation of PFAAs. Sediment, water, zooplankton, herring, sprat, and guillemot eggs were analyzed for perfluoroalkane sulfonic acids (PFSAs; C4,6,8,10) and perfluoroalkyl carboxylic acids (PFCAs; C6-15) along with six perfluoro-octane sulfonic acid (PFOS) precursors and 11 polyfluoroalkyl phosphoric acid diesters (diPAPs). FOSA, FOSAA and its methyl and ethyl derivatives (Me- and EtFOSAA), and 6:2/6:2 diPAP were detected in sediment and water. While FOSA and the three FOSAAs were detected in all biota, a total of nine diPAPs were only detected in zooplankton. Concentrations of PFOS precursors and diPAPs exceeded PFOS and PFCA concentrations, respectively, in zooplankton, but not in fish and guillemot eggs. Although PFOS precursors were present at all trophic levels, they appear to play a minor role in food web accumulation of PFOS based on PFOS precursor/PFOS ratios and PFOS and FOSA isomer patterns. The PFCA pattern in fish could not be explained by the intake pattern based on PFCAs and analyzed precursors, that is, diPAPs. Exposure to additional precursors might therefore be a dominant exposure pathway compared to direct PFCA exposure for fish.

  13. Methods of making copper selenium precursor compositions with a targeted copper selenide content and precursor compositions and thin films resulting therefrom

    Science.gov (United States)

    Curtis, Calvin J [Lakewood, CO; Miedaner, Alexander [Boulder, CO; van Hest, Marinus Franciscus Antonius Maria; Ginley, David S [Evergreen, CO; Leisch, Jennifer [Denver, CO; Taylor, Matthew [West Simsbury, CT; Stanbery, Billy J [Austin, TX

    2011-09-20

    Precursor compositions containing copper and selenium suitable for deposition on a substrate to form thin films suitable for semi-conductor applications. Methods of forming the precursor compositions using primary amine solvents and methods of forming the thin films wherein the selection of temperature and duration of heating controls the formation of a targeted species of copper selenide.

  14. Neural Decoder for Topological Codes

    Science.gov (United States)

    Torlai, Giacomo; Melko, Roger G.

    2017-07-01

    We present an algorithm for error correction in topological codes that exploits modern machine learning techniques. Our decoder is constructed from a stochastic neural network called a Boltzmann machine, of the type extensively used in deep learning. We provide a general prescription for the training of the network and a decoding strategy that is applicable to a wide variety of stabilizer codes with very little specialization. We demonstrate the neural decoder numerically on the well-known two-dimensional toric code with phase-flip errors.

  15. Entropy Learning in Neural Network

    Directory of Open Access Journals (Sweden)

    Geok See Ng

    2017-12-01

    Full Text Available In this paper, entropy term is used in the learning phase of a neural network.  As learning progresses, more hidden nodes get into saturation.  The early creation of such hidden nodes may impair generalisation.  Hence entropy approach is proposed to dampen the early creation of such nodes.  The entropy learning also helps to increase the importance of relevant nodes while dampening the less important nodes.  At the end of learning, the less important nodes can then be eliminated to reduce the memory requirements of the neural network.

  16. The neural cell adhesion molecule

    DEFF Research Database (Denmark)

    Berezin, V; Bock, E; Poulsen, F M

    2000-01-01

    During the past year, the understanding of the structure and function of neural cell adhesion has advanced considerably. The three-dimensional structures of several of the individual modules of the neural cell adhesion molecule (NCAM) have been determined, as well as the structure of the complex...... between two identical fragments of the NCAM. Also during the past year, a link between homophilic cell adhesion and several signal transduction pathways has been proposed, connecting the event of cell surface adhesion to cellular responses such as neurite outgrowth. Finally, the stimulation of neurite...

  17. Antenna analysis using neural networks

    Science.gov (United States)

    Smith, William T.

    1992-01-01

    Conventional computing schemes have long been used to analyze problems in electromagnetics (EM). The vast majority of EM applications require computationally intensive algorithms involving numerical integration and solutions to large systems of equations. The feasibility of using neural network computing algorithms for antenna analysis is investigated. The ultimate goal is to use a trained neural network algorithm to reduce the computational demands of existing reflector surface error compensation techniques. Neural networks are computational algorithms based on neurobiological systems. Neural nets consist of massively parallel interconnected nonlinear computational elements. They are often employed in pattern recognition and image processing problems. Recently, neural network analysis has been applied in the electromagnetics area for the design of frequency selective surfaces and beam forming networks. The backpropagation training algorithm was employed to simulate classical antenna array synthesis techniques. The Woodward-Lawson (W-L) and Dolph-Chebyshev (D-C) array pattern synthesis techniques were used to train the neural network. The inputs to the network were samples of the desired synthesis pattern. The outputs are the array element excitations required to synthesize the desired pattern. Once trained, the network is used to simulate the W-L or D-C techniques. Various sector patterns and cosecant-type patterns (27 total) generated using W-L synthesis were used to train the network. Desired pattern samples were then fed to the neural network. The outputs of the network were the simulated W-L excitations. A 20 element linear array was used. There were 41 input pattern samples with 40 output excitations (20 real parts, 20 imaginary). A comparison between the simulated and actual W-L techniques is shown for a triangular-shaped pattern. Dolph-Chebyshev is a different class of synthesis technique in that D-C is used for side lobe control as opposed to pattern

  18. Arabic Handwriting Recognition Using Neural Network Classifier

    African Journals Online (AJOL)

    pc

    2018-03-05

    Mar 5, 2018 ... an OCR using Neural Network classifier preceded by a set of preprocessing .... Artificial Neural Networks (ANNs), which we adopt in this research, consist of ... advantage and disadvantages of each technique. In [9],. Khemiri ...

  19. Neural overlap in processing music and speech.

    Science.gov (United States)

    Peretz, Isabelle; Vuvan, Dominique; Lagrois, Marie-Élaine; Armony, Jorge L

    2015-03-19

    Neural overlap in processing music and speech, as measured by the co-activation of brain regions in neuroimaging studies, may suggest that parts of the neural circuitries established for language may have been recycled during evolution for musicality, or vice versa that musicality served as a springboard for language emergence. Such a perspective has important implications for several topics of general interest besides evolutionary origins. For instance, neural overlap is an important premise for the possibility of music training to influence language acquisition and literacy. However, neural overlap in processing music and speech does not entail sharing neural circuitries. Neural separability between music and speech may occur in overlapping brain regions. In this paper, we review the evidence and outline the issues faced in interpreting such neural data, and argue that converging evidence from several methodologies is needed before neural overlap is taken as evidence of sharing. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  20. Application of neural networks in coastal engineering

    Digital Repository Service at National Institute of Oceanography (India)

    Mandal, S.

    the neural network attractive. A neural network is an information processing system modeled on the structure of the dynamic process. It can solve the complex/nonlinear problems quickly once trained by operating on problems using an interconnected number...

  1. Ocean wave forecasting using recurrent neural networks

    Digital Repository Service at National Institute of Oceanography (India)

    Mandal, S.; Prabaharan, N.

    , merchant vessel routing, nearshore construction, etc. more efficiently and safely. This paper describes an artificial neural network, namely recurrent neural network with rprop update algorithm and is applied for wave forecasting. Measured ocean waves off...

  2. Neural overlap in processing music and speech

    Science.gov (United States)

    Peretz, Isabelle; Vuvan, Dominique; Lagrois, Marie-Élaine; Armony, Jorge L.

    2015-01-01

    Neural overlap in processing music and speech, as measured by the co-activation of brain regions in neuroimaging studies, may suggest that parts of the neural circuitries established for language may have been recycled during evolution for musicality, or vice versa that musicality served as a springboard for language emergence. Such a perspective has important implications for several topics of general interest besides evolutionary origins. For instance, neural overlap is an important premise for the possibility of music training to influence language acquisition and literacy. However, neural overlap in processing music and speech does not entail sharing neural circuitries. Neural separability between music and speech may occur in overlapping brain regions. In this paper, we review the evidence and outline the issues faced in interpreting such neural data, and argue that converging evidence from several methodologies is needed before neural overlap is taken as evidence of sharing. PMID:25646513

  3. Predictors of withdrawal: possible precursors of avoidant personality disorder.

    Science.gov (United States)

    Eggum, Natalie D; Eisenberg, Nancy; Spinrad, Tracy L; Valiente, Carlos; Edwards, Alison; Kupfer, Anne S; Reiser, Mark

    2009-01-01

    Relations of avoidant personality disorder (AvPD) with shyness and inhibition suggest that a precursor of AvPD is withdrawal. Using a sample of 4.5- to 7-year-olds studied four times, 2 years apart, four and three classes of children differing in trajectories of mother- and teacher-reported withdrawal, respectively, were identified. Mothers and teachers generally did not agree on children's trajectories but the pattern of findings in the two contexts did not differ markedly. The mother-identified high and declining withdrawal class, in comparison with less withdrawn classes, and the teacher-identified high and declining class compared with low withdrawal classes, were associated with relatively high levels of anger and low levels of attentional control and resiliency. The mother-identified moderate and increasing withdrawal class was distinguished from less problematic withdrawal classes by higher anger, lower resiliency, and sometimes, lower attentional control. The teacher-identified low and increasing withdrawal class was distinguished from less problematic withdrawal classes by lower resiliency and lower attentional control. Findings are discussed in terms of the developmental precursors to social withdrawal and avoidant behavior.

  4. Precursors and metabolic pathway for guaiacol production by Alicyclobacillus acidoterrestris.

    Science.gov (United States)

    Cai, Rui; Yuan, Yahong; Wang, Zhouli; Guo, Chunfeng; Liu, Bin; Liu, Laping; Wang, Yutang; Yue, Tianli

    2015-12-02

    Alicyclobacillus acidoterrestris has recently received much attention due to its implication in the spoilage of pasteurized fruit juices, which was manifested by the production of guaiacol. Vanillic acid and vanillin have been accepted as the biochemical precursors of guaiacol in fruit juices. The purpose of this study was to try to find other precursors and elucidate details about the conversion of vanillic acid and vanillin to guaiacol by A. acidoterrestris. Four potential substrates including ferulic acid, catechol, phenylalanine and tyrosine were analyzed, but they could not be metabolized to guaiacol by all the thirty A. acidoterrestris strains tested. Resting cell studies and enzyme assays demonstrated that vanillin was reduced to vanillyl alcohol by NADPH-dependent vanillin reductase and oxidized to vanillic acid by NAD(P)(+)-dependent vanillin dehydrogenases in A. acidoterrestris DSM 3923. Vanillic acid underwent a nonoxidative decarboxylation to guaiacol. The reversible vanillic acid decarboxylase involved was oxygen insensitive and pyridine nucleotide-independent. Copyright © 2015. Published by Elsevier B.V.

  5. AMYPdb: A database dedicated to amyloid precursor proteins

    Directory of Open Access Journals (Sweden)

    Delamarche Christian

    2008-06-01

    Full Text Available Abstract Background Misfolding and aggregation of proteins into ordered fibrillar structures is associated with a number of severe pathologies, including Alzheimer's disease, prion diseases, and type II diabetes. The rapid accumulation of knowledge about the sequences and structures of these proteins allows using of in silico methods to investigate the molecular mechanisms of their abnormal conformational changes and assembly. However, such an approach requires the collection of accurate data, which are inconveniently dispersed among several generalist databases. Results We therefore created a free online knowledge database (AMYPdb dedicated to amyloid precursor proteins and we have performed large scale sequence analysis of the included data. Currently, AMYPdb integrates data on 31 families, including 1,705 proteins from nearly 600 organisms. It displays links to more than 2,300 bibliographic references and 1,200 3D-structures. A Wiki system is available to insert data into the database, providing a sharing and collaboration environment. We generated and analyzed 3,621 amino acid sequence patterns, reporting highly specific patterns for each amyloid family, along with patterns likely to be involved in protein misfolding and aggregation. Conclusion AMYPdb is a comprehensive online database aiming at the centralization of bioinformatic data regarding all amyloid proteins and their precursors. Our sequence pattern discovery and analysis approach unveiled protein regions of significant interest. AMYPdb is freely accessible 1.

  6. Redundancy and divergence in the amyloid precursor protein family.

    Science.gov (United States)

    Shariati, S Ali M; De Strooper, Bart

    2013-06-27

    Gene duplication provides genetic material required for functional diversification. An interesting example is the amyloid precursor protein (APP) protein family. The APP gene family has experienced both expansion and contraction during evolution. The three mammalian members have been studied quite extensively in combined knock out models. The underlying assumption is that APP, amyloid precursor like protein 1 and 2 (APLP1, APLP2) are functionally redundant. This assumption is primarily supported by the similarities in biochemical processing of APP and APLPs and on the fact that the different APP genes appear to genetically interact at the level of the phenotype in combined knockout mice. However, unique features in each member of the APP family possibly contribute to specification of their function. In the current review, we discuss the evolution and the biology of the APP protein family with special attention to the distinct properties of each homologue. We propose that the functions of APP, APLP1 and APLP2 have diverged after duplication to contribute distinctly to different neuronal events. Our analysis reveals that APLP2 is significantly diverged from APP and APLP1. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  7. A karyometric note on nucleoli in human early granulocytic precursors.

    Science.gov (United States)

    Smetana, K; Mikulenková, D; Jirásková, I; Klamová, H

    2006-01-01

    The diameter of nucleoli was measured in human bone marrow early granulocytic precursors after visualization by a simple cytochemical method for demonstration of RNA. Such method facilitated to clearly see nucleolar bodies without perinucleolar chromatin, including those of micronucleoli. The bone marrow of patients suffering from chronic myeloid leukaemia (untreated with cytostatics) provided a satisfactory number of both myeloblasts and promyelocytes for nucleolar measurements because of prevailing granulopoiesis. The direct nucleolar measurement was carried out on digitized and processed images on the screen at magnification 4,300x. It seems to be likely that the nucleolar size is directly related to the number of nucleoli per cell. The largest nucleoli were present in both myeloblasts and promyelocytes that possessed a single nucleolus. In contrast, the nucleolar diameter was significantly smaller in cells with multiple nucleoli. However, in cells with small multiple nucleoli, one of them was always larger and dominant with a large number of AgNORs. Such large nucleoli are possibly visible in specimens stained with panoptic procedures or methods staining nuclear chromatin or DNA. It should also be mentioned that both myeloblasts and promyelocytes mostly possessed two nucleoli with the mean diameter close to 1.5 microm. The incidence of early granulocytic precursors classified according to the nucleolar number and size strongly suggested that the various nucleolar number and nucleolar size in these cells might be related to the different stage of the cell cycle and might also explain their heterogeneity.

  8. High-quality CdTe films from nanoparticle precursors

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, D.L.; Pehnt, M.; Urgiles, E. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    In this paper the authors demonstrate that nanoparticulate precursors coupled with spray deposition offers an attractive route into electronic materials with improved smoothness, density, and lower processing temperatures. Employing a metathesis approach, cadmium iodide was reacted with sodium telluride in methanol solvent, resulting in the formation of soluble NaI and insoluble CdTe nanoparticles. After appropriate chemical workup, methanol-capped CdTe colloids were isolated. CdTe thin film formation was achieved by spray depositing the nanoparticle colloids (25-75 {Angstrom} diameter) onto substrates at elevated temperatures (T = 280-440{degrees}C) with no further thermal treatment. These films were characterized by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Cubic CdTe phase formation was observed by XRD, with a contaminant oxide phase also detected. XPS analysis showed that CdTe films produced by this one-step method contained no Na or C and substantial O. AFM gave CdTe grain sizes of {approx}0.1-0.3 {mu}m for film sprayed at 400{degrees}C. A layer-by-layer film growth mechanism proposed for the one-step spray deposition of nanoparticle precursors will be discussed.

  9. An Accident Precursor Analysis Process Tailored for NASA Space Systems

    Science.gov (United States)

    Groen, Frank; Stamatelatos, Michael; Dezfuli, Homayoon; Maggio, Gaspare

    2010-01-01

    Accident Precursor Analysis (APA) serves as the bridge between existing risk modeling activities, which are often based on historical or generic failure statistics, and system anomalies, which provide crucial information about the failure mechanisms that are actually operative in the system and which may differ in frequency or type from those in the various models. These discrepancies between the models (perceived risk) and the system (actual risk) provide the leading indication of an underappreciated risk. This paper presents an APA process developed specifically for NASA Earth-to-Orbit space systems. The purpose of the process is to identify and characterize potential sources of system risk as evidenced by anomalous events which, although not necessarily presenting an immediate safety impact, may indicate that an unknown or insufficiently understood risk-significant condition exists in the system. Such anomalous events are considered accident precursors because they signal the potential for severe consequences that may occur in the future, due to causes that are discernible from their occurrence today. Their early identification allows them to be integrated into the overall system risk model used to intbrm decisions relating to safety.

  10. Carbon fibre as a composites materials precursor-A review

    International Nuclear Information System (INIS)

    Ismail, A.F.; Yusof, N.; Mustafa, A.

    2010-01-01

    Carbon fibers are widely used as reinforcement in composite materials such as carbon fiber reinforced plastics, carbon fiber reinforced ceramics, carbon-carbon composites and carbon fiber reinforced metals, due to their high specific strength and modulus. Carbon fiber composites are ideally suited to applications where strength, stiffness, lower weight and outstanding fatigue characteristics are critical requirements. Generally, there are two main sectors of carbon fiber applications. Application of carbon fiber in high technology sectors includes aerospace and nuclear engineering whereby the use of carbon fiber is driven by maximum performance and not significantly influenced by cost factors. Meanwhile, the application in general engineering and transportations sector is dominated by cost constraints. Carbon fibers used in composites are often coated or surface treated to improve interaction between the fiber surface and the matrix. PAN/ CNT composite fibers are good candidates for the development of next generation carbon fibers with improved tensile strength and modulus while retaining its compressive strength. This paper aims at reviewing and critically discussing the fabrication aspects of carbon fiber for composites which can be divided into several sections: precursor selection, spinning process, pretreatment of the precursor, pyrolysis process, and also surface treatment of the carbon fiber. The future direction of carbon fiber for composite is also briefly identified to further extend the boundary of science and technology in order to fully exploit its potential. (author)

  11. The NAD(+) precursor nicotinamide riboside decreases exercise performance in rats.

    Science.gov (United States)

    Kourtzidis, Ioannis A; Stoupas, Andreas T; Gioris, Ioannis S; Veskoukis, Aristidis S; Margaritelis, Nikos V; Tsantarliotou, Maria; Taitzoglou, Ioannis; Vrabas, Ioannis S; Paschalis, Vassilis; Kyparos, Antonios; Nikolaidis, Michalis G

    2016-01-01

    Nicotinamide adenine dinucleotide (NAD(+)) and its phosphorylated form (NADP(+)) are key molecules in ubiquitous bioenergetic and cellular signaling pathways, regulating cellular metabolism and homeostasis. Thus, supplementation with NAD(+) and NADP(+) precursors emerged as a promising strategy to gain many and multifaceted health benefits. In this proof-of-concept study, we sought to investigate whether chronic nicotinamide riboside administration (an NAD(+) precursor) affects exercise performance. Eighteen Wistar rats were equally divided in two groups that received either saline vehicle or nicotinamide riboside at a dose of 300 mg/kg body weight/day for 21 days via gavage. At the end of the 21-day administration protocol, both groups performed an incremental swimming performance test. The nicotinamide riboside group showed a tendency towards worse physical performance by 35 % compared to the control group at the final 10 % load (94 ± 53 s for the nicotinamide riboside group and 145 ± 59 s for the control group; P = 0.071). Our results do not confirm the previously reported ergogenic effect of nicotinamide riboside. The potentially negative effect of nicotinamide riboside administration on physical performance may be attributed to the pleiotropic metabolic and redox properties of NAD(+) and NADP(+).

  12. Atomically precise graphene nanoribbon heterojunctions from a single molecular precursor

    Science.gov (United States)

    Nguyen, Giang D.; Tsai, Hsin-Zon; Omrani, Arash A.; Marangoni, Tomas; Wu, Meng; Rizzo, Daniel J.; Rodgers, Griffin F.; Cloke, Ryan R.; Durr, Rebecca A.; Sakai, Yuki; Liou, Franklin; Aikawa, Andrew S.; Chelikowsky, James R.; Louie, Steven G.; Fischer, Felix R.; Crommie, Michael F.

    2017-11-01

    The rational bottom-up synthesis of atomically defined graphene nanoribbon (GNR) heterojunctions represents an enabling technology for the design of nanoscale electronic devices. Synthetic strategies used thus far have relied on the random copolymerization of two electronically distinct molecular precursors to yield GNR heterojunctions. Here we report the fabrication and electronic characterization of atomically precise GNR heterojunctions prepared through late-stage functionalization of chevron GNRs obtained from a single precursor. Post-growth excitation of fully cyclized GNRs induces cleavage of sacrificial carbonyl groups, resulting in atomically well-defined heterojunctions within a single GNR. The GNR heterojunction structure was characterized using bond-resolved scanning tunnelling microscopy, which enables chemical bond imaging at T = 4.5 K. Scanning tunnelling spectroscopy reveals that band alignment across the heterojunction interface yields a type II heterojunction, in agreement with first-principles calculations. GNR heterojunction band realignment proceeds over a distance less than 1 nm, leading to extremely large effective fields.

  13. Novel drug delivery strategies for porphyrins and porphyrin precursors

    Science.gov (United States)

    Morrow, D. I. J.; Donnelly, R. F.

    2009-06-01

    superficial lesions, such as actinic keratosis. In addition, photodynamic antimicrobial chemotherapy (PACT) is attracting increasing interest for the treatment of infection. However, delivery strategies for topical PDT and PACT are still based on application of rather simplistic cream and solution formulations, with little consideration given to thermodynamics, targeting or the physicochemical properties of the active agent. Purpose-designed dosage forms for topical delivery of aminolevulinic acid or its esters include creams containing penetration enhancers and/or iron chelators, pressure sensitive patches and bioadhesive patches. Such systems aim to enhance drug delivery across the stratum corneum and keratinised debris overlying neoplastic lesions and improve subsequent protoporphyrin IX (PpIX) production. The alternative to using porphyrin precursors is the use of pre-formed photosensitisers. However, owing to their relatively high molecular weights, conventional topical application is not appropriate. Innovative strategies, such as the use of needle-free injections and microneedle arrays, bypass the stratum corneum, enabling rapid and targeted delivery not only porphyrin precursors but also pre-formed photosensitisers. This presentation will review drug delivery work published to date in the fields of PDT and PACT. In addition, the benefits of employing the latest advances in pharmaceutical technology will be highlighted.

  14. Radon anomaly in soil gas as an earthquake precursor

    International Nuclear Information System (INIS)

    Miklavcic, I.; Radolic, V.; Vukovic, B.; Poje, M.; Varga, M.; Stanic, D.; Planinic, J.

    2008-01-01

    The mechanical processes of earthquake preparation are always accompanied by deformations; afterwards, the complex short- or long-term precursory phenomena can appear. Anomalies of radon concentrations in soil gas are registered a few weeks or months before many earthquakes. Radon concentrations in soil gas were continuously measured by the LR-115 nuclear track detectors at site A (Osijek) during a 4-year period, as well as by the Barasol semiconductor detector at site B (Kasina) during 2 years. We investigated the influence of the meteorological parameters on the temporal radon variations, and we determined the equation of the multiple regression that enabled the reduction (deconvolution) of the radon variation caused by the barometric pressure, rainfall and temperature. The pre-earthquake radon anomalies at site A indicated 46% of the seismic events, on criterion M≥3, R<200 km, and 21% at site B. Empirical equations between earthquake magnitude, epicenter distance and precursor time enabled estimation or prediction of an earthquake that will rise at the epicenter distance R from the monitoring site in expecting precursor time T

  15. Radon anomaly in soil gas as an earthquake precursor

    Energy Technology Data Exchange (ETDEWEB)

    Miklavcic, I.; Radolic, V.; Vukovic, B.; Poje, M.; Varga, M.; Stanic, D. [Department of Physics, University of Osijek, Trg Ljudevita Gaja 6, POB 125, 31000 Osijek (Croatia); Planinic, J. [Department of Physics, University of Osijek, Trg Ljudevita Gaja 6, POB 125, 31000 Osijek (Croatia)], E-mail: planinic@ffos.hr

    2008-10-15

    The mechanical processes of earthquake preparation are always accompanied by deformations; afterwards, the complex short- or long-term precursory phenomena can appear. Anomalies of radon concentrations in soil gas are registered a few weeks or months before many earthquakes. Radon concentrations in soil gas were continuously measured by the LR-115 nuclear track detectors at site A (Osijek) during a 4-year period, as well as by the Barasol semiconductor detector at site B (Kasina) during 2 years. We investigated the influence of the meteorological parameters on the temporal radon variations, and we determined the equation of the multiple regression that enabled the reduction (deconvolution) of the radon variation caused by the barometric pressure, rainfall and temperature. The pre-earthquake radon anomalies at site A indicated 46% of the seismic events, on criterion M{>=}3, R<200 km, and 21% at site B. Empirical equations between earthquake magnitude, epicenter distance and precursor time enabled estimation or prediction of an earthquake that will rise at the epicenter distance R from the monitoring site in expecting precursor time T.

  16. Fabrication of superconducting wire using organometallic precursors and infiltration

    International Nuclear Information System (INIS)

    Lee, Y.J.

    1991-01-01

    Organometallic precursors from naphthenic acid and metal nitrates were used for the synthesis of YBCO oxide superconducting compounds. The characteristics of metal naphthenates as organometallic precursors were investigated by IR spectra, viscosity measurements, and infiltration. 123 superconducting compound obtained from 123 naphthenate showed a Tc of 90 degree K and a rather dense and elongated microstructure. Also, the melting behavior of Ba-cuprates which were used for 123 making was studied. A low-temperature melting process was developed to fabricate silver-sheathed superconducting wire with the powder-in-tube method; flowing argon gas is introduced to the system at 930-945 degree C to reduce the melting temperature of the 123 compound without silver sheath melting. It resulted in a 90 degree K Tc superconducting core with dense and locally aligned microstructure. SEM-EDS and XRD analysis, 4-probe resistance and Jc measurements, and carbon-content determinations were carried out to characterize the microstructure, grain alignment, and superconducting properties of the samples

  17. Rheology of YBa2Cu3O7-x precursors

    International Nuclear Information System (INIS)

    Green, T.M.; Akinc, M.

    1992-01-01

    Nitrate and acetate precursors to YBa 2 Cu 3 O 7-x (123) are prepared using a molten salt technique. The viscosity and shear stress of the paste are controlled by evaporation of water from the paste. The pastes contain ∼ 20--80 vol % solids. Rheometry over strain rates of 0--200 sec -1 shows both systems are shear-thinning. Both systems are thixotropic. The nitrate system may be described by a two-stage Bingham Plastic model, the acetate by a Hershel-Bulkley model. The existence of more than one region of flow behavior suggests that there are at least two mechanisms which contribute to flow. In the low strain rate region, flow resistance is due to the existence of flocs in the colloidal assembly. At higher strain rates, flow is probably controlled by interlaminar drag interactions. Precursors produced by both methods have been used to form fibers of YBa 2 Cu 3 o 7-x , by ram extrusion

  18. Silicone Resin Applications for Ceramic Precursors and Composites

    Directory of Open Access Journals (Sweden)

    Masaki Narisawa

    2010-06-01

    Full Text Available This article reviews the applications of silicone resins as ceramic precursors. The historical background of silicone synthesis chemistry is introduced to explain the production costs and supply availability of various silicones. Thermal degradation processes of silicones are classified in terms of the main chain structure and cyclic oligomer expulsion process, which determine the resulting ceramic yield and the chemical composition. The high temperature decomposition of Si-O-C beyond 1,400 °C in an inert atmosphere and formation of a protective silica layer on material surfaces beyond 1,200 °C in an oxidative atmosphere are discussed from the viewpoints of the wide chemical composition of the Si-O-C materials. Applications of the resins for binding agents, as starting materials for porous ceramics, matrix sources with impregnation, fiber spinning and ceramic adhesions are introduced. The recent development of the process of filler or cross-linking agent additions to resin compounds is also introduced. Such resin compounds are useful for obtaining thick coatings, MEMS parts and bulk ceramics, which are difficult to obtain by pyrolysis of simple organometallic precursors without additives.

  19. Ewing's sarcoma precursors are highly enriched in embryonic osteochondrogenic progenitors.

    Science.gov (United States)

    Tanaka, Miwa; Yamazaki, Yukari; Kanno, Yohei; Igarashi, Katsuhide; Aisaki, Ken-ichi; Kanno, Jun; Nakamura, Takuro

    2014-07-01

    Ewing's sarcoma is a highly malignant bone tumor found in children and adolescents, and the origin of this malignancy is not well understood. Here, we introduced a Ewing's sarcoma-associated genetic fusion of the genes encoding the RNA-binding protein EWS and the transcription factor ETS (EWS-ETS) into a fraction of cells enriched for osteochondrogenic progenitors derived from the embryonic superficial zone (eSZ) of long bones collected from late gestational murine embryos. EWS-ETS fusions efficiently induced Ewing's sarcoma-like small round cell sarcoma formation by these cells. Analysis of the eSZ revealed a fraction of a precursor cells that express growth/differentiation factor 5 (Gdf5), the transcription factor Erg, and parathyroid hormone-like hormone (Pthlh), and selection of the Pthlh-positive fraction alone further enhanced EWS-ETS-dependent tumor induction. Genes downstream of the EWS-ETS fusion protein were quite transcriptionally active in eSZ cells, especially in regions in which the chromatin structure of the ETS-responsive locus was open. Inhibition of β-catenin, poly (ADP-ribose) polymerase 1 (PARP1), or enhancer of zeste homolog 2 (EZH2) suppressed cell growth in a murine model of Ewing's sarcoma, suggesting the utility of the current system as a preclinical model. These results indicate that eSZ cells are highly enriched in precursors to Ewing's sarcoma and provide clues to the histogenesis of Ewing's sarcoma in bone.

  20. Airborne Precursors Predict Maternal Serum Perfluoroalkyl Acid Concentrations.

    Science.gov (United States)

    Makey, Colleen M; Webster, Thomas F; Martin, Jonathan W; Shoeib, Mahiba; Harner, Tom; Dix-Cooper, Linda; Webster, Glenys M

    2017-07-05

    Human exposure to persistent perfluoroalkyl acids (PFAAs), including perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorooctanesulfonate (PFOS), can occur directly from contaminated food, water, air, and dust. However, precursors to PFAAs (PreFAAs), such as dipolyfluoroalkyl phosphates (diPAPs), fluorotelomer alcohols (FTOHs), perfluorooctyl sulfonamides (FOSAs), and sulfonamidoethanols (FOSEs), which can be biotransformed to PFAAs, may also be a source of exposure. PFAAs were analyzed in 50 maternal sera samples collected in 2007-2008 from participants in Vancouver, Canada, while PFAAs and PreFAAs were measured in matching samples of residential bedroom air collected by passive sampler and in sieved vacuum dust (<150 μm). Concentrations of PreFAAs were higher than for PFAAs in air and dust. Positive associations were discovered between airborne 10:2 FTOH and serum PFOA and PFNA and between airborne MeFOSE and serum PFOS. On average, serum PFOS concentrations were 2.3 ng/mL (95%CI: 0.40, 4.3) higher in participants with airborne MeFOSE concentrations in the highest tertile relative to the lowest tertile. Among all PFAAs, only PFNA in air and vacuum dust predicted serum PFNA. Results suggest that airborne PFAA precursors were a source of PFOA, PFNA, and PFOS exposure in this population.

  1. MEMBRAIN NEURAL NETWORK FOR VISUAL PATTERN RECOGNITION

    Directory of Open Access Journals (Sweden)

    Artur Popko

    2013-06-01

    Full Text Available Recognition of visual patterns is one of significant applications of Artificial Neural Networks, which partially emulate human thinking in the domain of artificial intelligence. In the paper, a simplified neural approach to recognition of visual patterns is portrayed and discussed. This paper is dedicated for investigators in visual patterns recognition, Artificial Neural Networking and related disciplines. The document describes also MemBrain application environment as a powerful and easy to use neural networks’ editor and simulator supporting ANN.

  2. Neural network to diagnose lining condition

    Science.gov (United States)

    Yemelyanov, V. A.; Yemelyanova, N. Y.; Nedelkin, A. A.; Zarudnaya, M. V.

    2018-03-01

    The paper presents data on the problem of diagnosing the lining condition at the iron and steel works. The authors describe the neural network structure and software that are designed and developed to determine the lining burnout zones. The simulation results of the proposed neural networks are presented. The authors note the low learning and classification errors of the proposed neural networks. To realize the proposed neural network, the specialized software has been developed.

  3. Simplified LQG Control with Neural Networks

    DEFF Research Database (Denmark)

    Sørensen, O.

    1997-01-01

    A new neural network application for non-linear state control is described. One neural network is modelled to form a Kalmann predictor and trained to act as an optimal state observer for a non-linear process. Another neural network is modelled to form a state controller and trained to produce...

  4. Analysis of neural networks through base functions

    NARCIS (Netherlands)

    van der Zwaag, B.J.; Slump, Cornelis H.; Spaanenburg, L.

    Problem statement. Despite their success-story, neural networks have one major disadvantage compared to other techniques: the inability to explain comprehensively how a trained neural network reaches its output; neural networks are not only (incorrectly) seen as a "magic tool" but possibly even more

  5. Genetic Algorithm Optimized Neural Networks Ensemble as ...

    African Journals Online (AJOL)

    NJD

    Improvements in neural network calibration models by a novel approach using neural network ensemble (NNE) for the simultaneous ... process by training a number of neural networks. .... Matlab® version 6.1 was employed for building principal component ... provide a fair simulation of calibration data set with some degree.

  6. Recycling signals in the neural crest

    OpenAIRE

    Taneyhill, Lisa A.; Bronner-Fraser, Marianne E.

    2006-01-01

    Vertebrate neural crest cells are multipotent and differentiate into structures that include cartilage and the bones of the face, as well as much of the peripheral nervous system. Understanding how different model vertebrates utilize signaling pathways reiteratively during various stages of neural crest formation and differentiation lends insight into human disorders associated with the neural crest.

  7. Recycling signals in the neural crest.

    Science.gov (United States)

    Taneyhill, Lisa A; Bronner-Fraser, Marianne

    2005-01-01

    Vertebrate neural crest cells are multipotent and differentiate into structures that include cartilage and the bones of the face, as well as much of the peripheral nervous system. Understanding how different model vertebrates utilize signaling pathways reiteratively during various stages of neural crest formation and differentiation lends insight into human disorders associated with the neural crest.

  8. Anger under control: neural correlates of frustration as a function of trait aggression.

    Directory of Open Access Journals (Sweden)

    Christina M Pawliczek

    Full Text Available Antisocial behavior and aggression are prominent symptoms in several psychiatric disorders including antisocial personality disorder. An established precursor to aggression is a frustrating event, which can elicit anger or exasperation, thereby prompting aggressive responses. While some studies have investigated the neural correlates of frustration and aggression, examination of their relation to trait aggression in healthy populations are rare. Based on a screening of 550 males, we formed two extreme groups, one including individuals reporting high (n=21 and one reporting low (n=18 trait aggression. Using functional magnetic resonance imaging (fMRI at 3T, all participants were put through a frustration task comprising unsolvable anagrams of German nouns. Despite similar behavioral performance, males with high trait aggression reported higher ratings of negative affect and anger after the frustration task. Moreover, they showed relatively decreased activation in the frontal brain regions and the dorsal anterior cingulate cortex (dACC as well as relatively less amygdala activation in response to frustration. Our findings indicate distinct frontal and limbic processing mechanisms following frustration modulated by trait aggression. In response to a frustrating event, HA individuals show some of the personality characteristics and neural processing patterns observed in abnormally aggressive populations. Highlighting the impact of aggressive traits on the behavioral and neural responses to frustration in non-psychiatric extreme groups can facilitate further characterization of neural dysfunctions underlying psychiatric disorders that involve abnormal frustration processing and aggression.

  9. Modeling Cerebrovascular Pathophysiology in Amyloid-β Metabolism using Neural-Crest-Derived Smooth Muscle Cells

    Directory of Open Access Journals (Sweden)

    Christine Cheung

    2014-10-01

    Full Text Available Summary: There is growing recognition of cerebrovascular contributions to neurodegenerative diseases. In the walls of cerebral arteries, amyloid-beta (Aβ accumulation is evident in a majority of aged people and patients with cerebral amyloid angiopathy. Here, we leverage human pluripotent stem cells to generate vascular smooth muscle cells (SMCs from neural crest progenitors, recapitulating brain-vasculature-specific attributes of Aβ metabolism. We confirm that the lipoprotein receptor, LRP1, functions in our neural-crest-derived SMCs to mediate Aβ uptake and intracellular lysosomal degradation. Hypoxia significantly compromises the contribution of SMCs to Aβ clearance by suppressing LRP1 expression. This enabled us to develop an assay of Aβ uptake by using the neural crest-derived SMCs with hypoxia as a stress paradigm. We then tested several vascular protective compounds in a high-throughput format, demonstrating the value of stem-cell-based phenotypic screening for novel therapeutics and drug repurposing, aimed at alleviating amyloid burden. : The contribution of blood vessel pathologies to neurodegenerative disorders is relatively neglected, partly due to inadequate human tissues for research. By using human stem cells, Cheung et al. establish a method of generating vascular smooth muscle cells (SMCs from neural crest progenitors, the primary precursors that give rise to brain blood vessels. These stem-cell-derived SMCs display defective amyloid processing under chronic hypoxia, a phenomenon well documented in the cerebral vasculatures of aged people and patients with Alzheimer’s disease.

  10. Methods of forming single source precursors, methods of forming polymeric single source precursors, and single source precursors and intermediate products formed by such methods

    Science.gov (United States)

    Fox, Robert V.; Rodriguez, Rene G.; Pak, Joshua J.; Sun, Chivin; Margulieux, Kelsey R.; Holland, Andrew W.

    2012-12-04

    Methods of forming single source precursors (SSPs) include forming intermediate products having the empirical formula 1/2{L.sub.2N(.mu.-X).sub.2M'X.sub.2}.sub.2, and reacting MER with the intermediate products to form SSPs of the formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2, wherein L is a Lewis base, M is a Group IA atom, N is a Group IB atom, M' is a Group IIIB atom, each E is a Group VIB atom, each X is a Group VIIA atom or a nitrate group, and each R group is an alkyl, aryl, vinyl, (per)fluoro alkyl, (per)fluoro aryl, silane, or carbamato group. Methods of forming polymeric or copolymeric SSPs include reacting at least one of HE.sup.1R.sup.1E.sup.1H and MER with one or more substances having the empirical formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2 or L.sub.2N(.mu.-X).sub.2M'(X).sub.2 to form a polymeric or copolymeric SSP. New SSPs and intermediate products are formed by such methods.

  11. Methods of forming single source precursors, methods of forming polymeric single source precursors, and single source precursors formed by such methods

    Science.gov (United States)

    Fox, Robert V.; Rodriguez, Rene G.; Pak, Joshua J.; Sun, Chivin; Margulieux, Kelsey R.; Holland, Andrew W.

    2014-09-09

    Methods of forming single source precursors (SSPs) include forming intermediate products having the empirical formula 1/2{L.sub.2N(.mu.-X).sub.2M'X.sub.2}.sub.2, and reacting MER with the intermediate products to form SSPs of the formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2, wherein L is a Lewis base, M is a Group IA atom, N is a Group IB atom, M' is a Group IIIB atom, each E is a Group VIB atom, each X is a Group VIIA atom or a nitrate group, and each R group is an alkyl, aryl, vinyl, (per)fluoro alkyl, (per)fluoro aryl, silane, or carbamato group. Methods of forming polymeric or copolymeric SSPs include reacting at least one of HE.sup.1R.sup.1E.sup.1H and MER with one or more substances having the empirical formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2 or L.sub.2N(.mu.-X).sub.2M'(X).sub.2 to form a polymeric or copolymeric SSP. New SSPs and intermediate products are formed by such methods.

  12. Neural chips, neural computers and application in high and superhigh energy physics experiments

    International Nuclear Information System (INIS)

    Nikityuk, N.M.; )

    2001-01-01

    Architecture peculiarity and characteristics of series of neural chips and neural computes used in scientific instruments are considered. Tendency of development and use of them in high energy and superhigh energy physics experiments are described. Comparative data which characterize the efficient use of neural chips for useful event selection, classification elementary particles, reconstruction of tracks of charged particles and for search of hypothesis Higgs particles are given. The characteristics of native neural chips and accelerated neural boards are considered [ru

  13. Medical Imaging with Neural Networks

    International Nuclear Information System (INIS)

    Pattichis, C.; Cnstantinides, A.

    1994-01-01

    The objective of this paper is to provide an overview of the recent developments in the use of artificial neural networks in medical imaging. The areas of medical imaging that are covered include : ultrasound, magnetic resonance, nuclear medicine and radiological (including computerized tomography). (authors)

  14. Optoelectronic Implementation of Neural Networks

    Indian Academy of Sciences (India)

    neural networks, such as learning, adapting and copying by means of parallel ... to provide robust recognition of hand-printed English text. Engine idle and misfiring .... and s represents the bounded activation function of a neuron. It is typically ...

  15. Aphasia Classification Using Neural Networks

    DEFF Research Database (Denmark)

    Axer, H.; Jantzen, Jan; Berks, G.

    2000-01-01

    A web-based software model (http://fuzzy.iau.dtu.dk/aphasia.nsf) was developed as an example for classification of aphasia using neural networks. Two multilayer perceptrons were used to classify the type of aphasia (Broca, Wernicke, anomic, global) according to the results in some subtests...

  16. Intelligent neural network diagnostic system

    International Nuclear Information System (INIS)

    Mohamed, A.H.

    2010-01-01

    Recently, artificial neural network (ANN) has made a significant mark in the domain of diagnostic applications. Neural networks are used to implement complex non-linear mappings (functions) using simple elementary units interrelated through connections with adaptive weights. The performance of the ANN is mainly depending on their topology structure and weights. Some systems have been developed using genetic algorithm (GA) to optimize the topology of the ANN. But, they suffer from some limitations. They are : (1) The computation time requires for training the ANN several time reaching for the average weight required, (2) Slowness of GA for optimization process and (3) Fitness noise appeared in the optimization of ANN. This research suggests new issues to overcome these limitations for finding optimal neural network architectures to learn particular problems. This proposed methodology is used to develop a diagnostic neural network system. It has been applied for a 600 MW turbo-generator as a case of real complex systems. The proposed system has proved its significant performance compared to two common methods used in the diagnostic applications.

  17. Medical Imaging with Neural Networks

    Energy Technology Data Exchange (ETDEWEB)

    Pattichis, C [Department of Computer Science, University of Cyprus, Kallipoleos 75, P.O.Box 537, Nicosia (Cyprus); Cnstantinides, A [Department of Electrical Engineering, Imperial College of Science, Technology and Medicine, London SW7 2BT (United Kingdom)

    1994-12-31

    The objective of this paper is to provide an overview of the recent developments in the use of artificial neural networks in medical imaging. The areas of medical imaging that are covered include : ultrasound, magnetic resonance, nuclear medicine and radiological (including computerized tomography). (authors). 61 refs, 4 tabs.

  18. Numerical experiments with neural networks

    International Nuclear Information System (INIS)

    Miranda, Enrique.

    1990-01-01

    Neural networks are highly idealized models which, in spite of their simplicity, reproduce some key features of the real brain. In this paper, they are introduced at a level adequate for an undergraduate computational physics course. Some relevant magnitudes are defined and evaluated numerically for the Hopfield model and a short term memory model. (Author)

  19. Serotonin, neural markers and memory

    Directory of Open Access Journals (Sweden)

    Alfredo eMeneses

    2015-07-01

    Full Text Available Diverse neuropsychiatric disorders present dysfunctional memory and no effective treatment exits for them; likely as result of the absence of neural markers associated to memory. Neurotransmitter systems and signaling pathways have been implicated in memory and dysfunctional memory; however, their role is poorly understood. Hence, neural markers and cerebral functions and dysfunctions are revised. To our knowledge no previous systematic works have been published addressing these issues. The interactions among behavioral tasks, control groups and molecular changes and/or pharmacological effects are mentioned. Neurotransmitter receptors and signaling pathways, during normal and abnormally functioning memory with an emphasis on the behavioral aspects of memory are revised. With focus on serotonin, since as it is a well characterized neurotransmitter, with multiple pharmacological tools, and well characterized downstream signaling in mammals’ species. 5-HT1A, 5-HT4, 5-HT5, 5-HT6 and 5-HT7 receptors as well as SERT (serotonin transporter seem to be useful neural markers and/or therapeutic targets. Certainly, if the mentioned evidence is replicated, then the translatability from preclinical and clinical studies to neural changes might be confirmed. Hypothesis and theories might provide appropriate limits and perspectives of evidence

  20. Neural correlates of viewing paintings

    DEFF Research Database (Denmark)

    Vartanian, Oshin; Skov, Martin

    2014-01-01

    Many studies involving functional magnetic resonance imaging (fMRI) have exposed participants to paintings under varying task demands. To isolate neural systems that are activated reliably across fMRI studies in response to viewing paintings regardless of variation in task demands, a quantitative...

  1. Neural Basis of Visual Distraction

    Science.gov (United States)

    Kim, So-Yeon; Hopfinger, Joseph B.

    2010-01-01

    The ability to maintain focus and avoid distraction by goal-irrelevant stimuli is critical for performing many tasks and may be a key deficit in attention-related problems. Recent studies have demonstrated that irrelevant stimuli that are consciously perceived may be filtered out on a neural level and not cause the distraction triggered by…

  2. Vestibular hearing and neural synchronization.

    Science.gov (United States)

    Emami, Seyede Faranak; Daneshi, Ahmad

    2012-01-01

    Objectives. Vestibular hearing as an auditory sensitivity of the saccule in the human ear is revealed by cervical vestibular evoked myogenic potentials (cVEMPs). The range of the vestibular hearing lies in the low frequency. Also, the amplitude of an auditory brainstem response component depends on the amount of synchronized neural activity, and the auditory nerve fibers' responses have the best synchronization with the low frequency. Thus, the aim of this study was to investigate correlation between vestibular hearing using cVEMPs and neural synchronization via slow wave Auditory Brainstem Responses (sABR). Study Design. This case-control survey was consisted of twenty-two dizzy patients, compared to twenty healthy controls. Methods. Intervention comprised of Pure Tone Audiometry (PTA), Impedance acoustic metry (IA), Videonystagmography (VNG), fast wave ABR (fABR), sABR, and cVEMPs. Results. The affected ears of the dizzy patients had the abnormal findings of cVEMPs (insecure vestibular hearing) and the abnormal findings of sABR (decreased neural synchronization). Comparison of the cVEMPs at affected ears versus unaffected ears and the normal persons revealed significant differences (P < 0.05). Conclusion. Safe vestibular hearing was effective in the improvement of the neural synchronization.

  3. Spin glasses and neural networks

    International Nuclear Information System (INIS)

    Parga, N.; Universidad Nacional de Cuyo, San Carlos de Bariloche

    1989-01-01

    The mean-field theory of spin glass models has been used as a prototype of systems with frustration and disorder. One of the most interesting related systems are models of associative memories. In these lectures we review the main concepts developed to solve the Sherrington-Kirkpatrick model and its application to neural networks. (orig.)

  4. Non-invasive neural stimulation

    Science.gov (United States)

    Tyler, William J.; Sanguinetti, Joseph L.; Fini, Maria; Hool, Nicholas

    2017-05-01

    Neurotechnologies for non-invasively interfacing with neural circuits have been evolving from those capable of sensing neural activity to those capable of restoring and enhancing human brain function. Generally referred to as non-invasive neural stimulation (NINS) methods, these neuromodulation approaches rely on electrical, magnetic, photonic, and acoustic or ultrasonic energy to influence nervous system activity, brain function, and behavior. Evidence that has been surmounting for decades shows that advanced neural engineering of NINS technologies will indeed transform the way humans treat diseases, interact with information, communicate, and learn. The physics underlying the ability of various NINS methods to modulate nervous system activity can be quite different from one another depending on the energy modality used as we briefly discuss. For members of commercial and defense industry sectors that have not traditionally engaged in neuroscience research and development, the science, engineering and technology required to advance NINS methods beyond the state-of-the-art presents tremendous opportunities. Within the past few years alone there have been large increases in global investments made by federal agencies, foundations, private investors and multinational corporations to develop advanced applications of NINS technologies. Driven by these efforts NINS methods and devices have recently been introduced to mass markets via the consumer electronics industry. Further, NINS continues to be explored in a growing number of defense applications focused on enhancing human dimensions. The present paper provides a brief introduction to the field of non-invasive neural stimulation by highlighting some of the more common methods in use or under current development today.

  5. Neural networks and applications tutorial

    Science.gov (United States)

    Guyon, I.

    1991-09-01

    The importance of neural networks has grown dramatically during this decade. While only a few years ago they were primarily of academic interest, now dozens of companies and many universities are investigating the potential use of these systems and products are beginning to appear. The idea of building a machine whose architecture is inspired by that of the brain has roots which go far back in history. Nowadays, technological advances of computers and the availability of custom integrated circuits, permit simulations of hundreds or even thousands of neurons. In conjunction, the growing interest in learning machines, non-linear dynamics and parallel computation spurred renewed attention in artificial neural networks. Many tentative applications have been proposed, including decision systems (associative memories, classifiers, data compressors and optimizers), or parametric models for signal processing purposes (system identification, automatic control, noise canceling, etc.). While they do not always outperform standard methods, neural network approaches are already used in some real world applications for pattern recognition and signal processing tasks. The tutorial is divided into six lectures, that where presented at the Third Graduate Summer Course on Computational Physics (September 3-7, 1990) on Parallel Architectures and Applications, organized by the European Physical Society: (1) Introduction: machine learning and biological computation. (2) Adaptive artificial neurons (perceptron, ADALINE, sigmoid units, etc.): learning rules and implementations. (3) Neural network systems: architectures, learning algorithms. (4) Applications: pattern recognition, signal processing, etc. (5) Elements of learning theory: how to build networks which generalize. (6) A case study: a neural network for on-line recognition of handwritten alphanumeric characters.

  6. The presence of modifiable residues in the core peptide part of precursor nisin is not crucial for precursor nisin interactions with NisB- and NisC.

    Directory of Open Access Journals (Sweden)

    Rustem Khusainov

    Full Text Available Precursor nisin is a model posttranslationally modified precursor lantibiotic that can be structurally divided into a leader peptide sequence and a modifiable core peptide part. The nisin core peptide clearly plays an important role in the precursor nisin-nisin modification enzymes interactions, since it has previously been shown that the construct containing only the nisin leader sequence is not sufficient to pull-down the nisin modification enzymes NisB and NisC. Serines and threonines in the core peptide part are the residues that NisB specifically dehydrates, and cysteines are the residues that NisC stereospecifically couples to the dehydrated amino acids. Here, we demonstrate that increasing the number of negatively charged residues in the core peptide part of precursor nisin, which are absent in wild-type nisin, does not abolish binding of precursor nisin to the modification enzymes NisB and NisC, but dramatically decreases the antimicrobial potency of these nisin mutants. An unnatural precursor nisin variant lacking all serines and threonines in the core peptide part and an unnatural precursor nisin variant lacking all cysteines in the core peptide part still bind the nisin modification enzymes NisB and NisC, suggesting that these residues are not essential for direct interactions with the nisin modification enzymes NisB and NisC. These results are important for lantibiotic engineering studies.

  7. Parameterization Of Solar Radiation Using Neural Network

    International Nuclear Information System (INIS)

    Jiya, J. D.; Alfa, B.

    2002-01-01

    This paper presents a neural network technique for parameterization of global solar radiation. The available data from twenty-one stations is used for training the neural network and the data from other ten stations is used to validate the neural model. The neural network utilizes latitude, longitude, altitude, sunshine duration and period number to parameterize solar radiation values. The testing data was not used in the training to demonstrate the performance of the neural network in unknown stations to parameterize solar radiation. The results indicate a good agreement between the parameterized solar radiation values and actual measured values

  8. Aqueous-Containing Precursor Solutions for Efficient Perovskite Solar Cells.

    Science.gov (United States)

    Liu, Dianyi; Traverse, Christopher J; Chen, Pei; Elinski, Mark; Yang, Chenchen; Wang, Lili; Young, Margaret; Lunt, Richard R

    2018-01-01

    Perovskite semiconductors have emerged as competitive candidates for photovoltaic applications due to their exceptional optoelectronic properties. However, the impact of moisture instability on perovskite films is still a key challenge for perovskite devices. While substantial effort is focused on preventing moisture interaction during the fabrication process, it is demonstrated that low moisture sensitivity, enhanced crystallization, and high performance can actually be achieved by exposure to high water content (up to 25 vol%) during fabrication with an aqueous-containing perovskite precursor. The perovskite solar cells fabricated by this aqueous method show good reproducibility of high efficiency with average power conversion efficiency (PCE) of 18.7% and champion PCE of 20.1% under solar simulation. This study shows that water-perovskite interactions do not necessarily negatively impact the perovskite film preparation process even at the highest efficiencies and that exposure to high contents of water can actually enable humidity tolerance during fabrication in air.

  9. Method for forecasting an earthquake from precursor signals

    International Nuclear Information System (INIS)

    Farnworth, D.F.

    1996-01-01

    A method for forecasting an earthquake from precursor signals by employing characteristic first electromagnetic signals, second, seismically induced electromagnetic signals, seismically induced mechanical signals, and infrasonic acoustic signals which have been observed to precede an earthquake. From a first electromagnetic signal, a magnitude, depth beneath the surface of the earth, distance, latitude, longitude, and first and second forecasts of the time of occurrence of the impending earthquake may be derived. From a second, seismically induced electromagnetic signal and the mechanical signal, third and fourth forecasts of the time of occurrence of an impending earthquake determined from the analysis above, a magnitude, depth beneath the surface of the earth and fourth and fifth forecasts of the time of occurrence of the impending earthquake may be derived. The forecasts of time available from the above analyses range from up to five weeks to substantially within one hour in advance of the earthquake. (author)

  10. Low frequency sawtooth precursor activity in ASDEX Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Papp, G; Pokol, G I; Por, G; Magyarkuti, A; Lazanyi, N; Horvath, L [Department of Nuclear Techniques, Budapest University of Technology and Economics, Association EURATOM, Pf 91, H-1521 Budapest (Hungary); Igochine, V; Maraschek, M, E-mail: papp@reak.bme.h [Max-Planck-Institut fuer Plasmaphysik, Association EURATOM, D-85748 Garching (Germany)

    2011-06-15

    This paper describes the precursor activity observed in the ASDEX Upgrade tokamak before sawtooth crashes in various neutral beam heated plasmas, utilizing the soft x-ray diagnostic. In addition to the well-known (m, n) = (1,1) internal kink mode and its harmonics, a lower frequency mode is studied in detail. Power modulation of this mode is found to correlate with the power modulation of the (1, 1) kink mode in the quasistationary intervals indicating possible nonlinear interaction. Throughout the studied sawtooth crashes, the power of the lower frequency mode rose by several orders of magnitude just before the crash. In addition to its temporal behaviour, its spatial structure was estimated and the most likely value was found to be (1, 1). A possible role of this mode in the mechanism of the sawtooth crash is discussed.

  11. Natural Modulators of Amyloid-Beta Precursor Protein Processing

    Science.gov (United States)

    Zhang, Can; Tanzi, Rudolph E.

    2013-01-01

    Alzheimer’s disease (AD) is a devastating neurodegenerative disease and the primary cause of dementia, with no cure currently available. The pathogenesis of AD is believed to be primarily driven by Aβ, the principal component of senile plaques. Aβ is an ~4 kDa peptide generated from the amyloid-β precursor protein (APP) through proteolytic secretases. Natural products, particularly those utilized in traditional Chinese medicine (TCM), have a long history alleviating common clinical disorders, including dementia. However, the cell/molecular pathways mediated by these natural products are largely unknown until recently when the underlying molecular mechanisms of the disorders begin to be elucidated. Here, the mechanisms with which natural products modulate the pathogenesis of AD are discussed, in particular, by focusing on their roles in the processing of APP. PMID:22998566

  12. Summary of ceramic pigments by polymer precursors Pechini method

    International Nuclear Information System (INIS)

    Silva, E.M. da; Galvao, S.B.; Paskocimas, C.A.

    2010-01-01

    In this work were synthesized nitrate chromium nitrate and iron-doped titanium oxide by the polymeric precursor method, for application as ceramic pigments. The stains were developed between the temperatures 700 deg C to 1000 deg C, in green for chromium oxide and orange for iron. Noticing an increase of its opacity by increasing temperature. Characterization by thermogravimetry (TG) showed strong thermo decomposition from 355 deg C for the chromium oxide and thermo decomposition gradual for the iron. By analysis of X-ray diffraction revealed the formation of crystalline phases as Iron Titanate (FeTiO3) and Chrome Titanate (CrTiO3), respectively. The scanning electron microscopy showed the formation of rounded particles for both oxides. Thus, the synthesized oxides were within the requirements to be applied as pigments and shown to be possible to propose its use in ceramic materials. (author)

  13. Illegal or legitimate use? Precursor compounds to amphetamine and methamphetamine.

    Science.gov (United States)

    Musshoff, F

    2000-02-01

    The interpretation of methamphetamine and amphetamine positive test results in biological samples is a challenge to clinical and forensic toxicology for several reasons. The effects of pH and dilution of urine samples and the knowledge about legitimate and illicit sources have to be taken into account. Besides a potentially legal prescription of amphetamines, many substances metabolize to methamphetamine or amphetamine in the body: amphetaminil, benzphetamine, clobenzorex, deprenyl, dimethylamphetamine, ethylamphetamine, famprofazone, fencamine, fenethylline, fenproporex, furfenorex, mefenorex, mesocarb, and prenylamine. Especially the knowledge of potential origins of methamphetamine and amphetamine turns out to be very important to prevent a misinterpretation of the surrounding circumstances and to prove illegal drug abuse. In this review, potential precursor compounds are described, including their medical use and major clinical effects and their metabolic profiles, as well as some clues which help to identify the sources.

  14. Resonant infrared pulsed laser deposition of a polyimide precursor

    Energy Technology Data Exchange (ETDEWEB)

    Dygert, N L; Schriver, K E; Jr, R F Haglund [Department of Physics and Astronomy and W M Keck Foundation Free-Electron Laser Centre, Vanderbilt University, Nashville TN 37235 (United States)

    2007-04-15

    Poly(amic acid) (PAA), a precursor to polyimide, was successfully deposited on substrates without reaching curing temperature, by resonant infrared pulsed laser ablation. The PAA was prepared by dissolving pyromellitic dianhydride and 4, 4' oxidianiline in the polar solvent Nmethyl pyrrolidinone (NMP). The PAA was deposited in droplet-like morphologies when ablation occurred in air, and in string-like moieties in the case of ablation in vacuum. In the as-deposited condition, the PAA was easily removed by washing with NMP; however, once cured thermally for thirty minutes, the PAA hardened, indicating the expected thermosetting property. Plume shadowgraphy showed very clear contrasts in the ablation mechanism between ablation of the solvent alone and the ablation of the PAA, even at low concentrations. A Wavelength dependence in plume velocity was also observed.

  15. Effects of Roughness and Inertia on Precursors to Frictional Sliding

    Science.gov (United States)

    Robbins, Mark O.; Salerno, K. Michael

    2012-02-01

    Experiments show that when a PMMA block on a surface is normally loaded and driven by an external shear force, contact at the interface is modified in discrete precursor slips prior to steady state sliding.[1] Our simulations use an atomistic model of a rough two-dimensional block in contact with a flat surface to investigate the evolution of stress and displacement along the contact between surfaces. The talk will show how local and global stress conditions govern the initiation of interfacial cracks as well as the spatial extension of the cracked region. Inertia also plays an important role in determining the number and size of slips before sliding and influences the distribution of stresses at the interface. Finally, the geometry of surface asperities also influences the interfacial evolution and the total friction force. The relationship between the interfacial stress state and rupture velocity will also be discussed. [1] S.M. Rubinstein, G. Cohen and J. Fineberg, PRL 98, 226103 (2007)

  16. Multiple Modes of Communication between Neurons and Oligodendrocyte Precursor Cells.

    Science.gov (United States)

    Maldonado, Paloma P; Angulo, María Cecilia

    2015-06-01

    The surprising discovery of bona fide synapses between neurons and oligodendrocytes precursor cells (OPCs) 15 years ago placed these progenitors as real partners of neurons in the CNS. The role of these synapses has not been established yet, but a main hypothesis is that neuron-OPC synaptic activity is a signaling pathway controlling OPC proliferation/differentiation, influencing the myelination process. However, new evidences describing non-synaptic mechanisms of communication between neurons and OPCs have revealed that neuron-OPC interactions are more complex than expected. The activation of extrasynaptic receptors by ambient neurotransmitter or local spillover and the ability of OPCs to sense neuronal activity through a potassium channel suggest that distinct modes of communication mediate different functions of OPCs in the CNS. This review discusses different mechanisms used by OPCs to interact with neurons and their potential roles during postnatal development and in brain disorders. © The Author(s) 2014.

  17. C-type natriuretic peptide and its precursor

    DEFF Research Database (Denmark)

    Lippert, Solvej; Iversen, Peter; Brasso, Klaus

    2015-01-01

    AIM: Seminal plasma offer a more organ-specific matrix for markers in prostatic disease. We hypothesized that C-type natriuretic peptide (CNP) expression may constitute such a new target. METHODS: Patients with benign prostatic hyperplasia, clinically localized and metastatic prostate cancer were...... examined for CNP and CNP precursor (proCNP) concentrations in blood and seminal plasma. Furthermore, CNP and the CNP receptor (NPR-B) mRNA contents in tissue from prostate and seminal vesicles were analyzed by qPCR. RESULTS: CNP and NPR-B concentrations decreased with increasing tumor burden (p = 0.......0027 and p = 0.0096, respectively). In contrast, seminal plasma CNP and proCNP concentrations were markedly increased with increased tumor burden (p prostate cancer....

  18. Proteomic analysis of osteogenic differentiation of dental follicle precursor cells

    DEFF Research Database (Denmark)

    Morsczeck, Christian; Petersen, Jørgen; Völlner, Florian

    2009-01-01

    of differentiation. In the present study we applied 2-DE combined with capillary-LC-MS/MS analysis to profile differentially regulated proteins upon differentiation of dental follicle precursor cells (DFPCs). Out of 115 differentially regulated proteins, glutamine synthetase, lysosomal proteinase cathepsin B....... The bioinformatic analyses suggest that proteins associated with cell cycle progression and protein metabolism were down-regulated and proteins involved in catabolism, cell motility and biological quality were up-regulated. These results display the general physiological state of DFPCs before and after osteogenic...... proteins, plastin 3 T-isoform, beta-actin, superoxide dismutases, and transgelin were found to be highly up-regulated, whereas cofilin-1, pro-alpha 1 collagen, destrin, prolyl 4-hydrolase and dihydrolipoamide dehydrogenase were found to be highly down-regulated. The group of up-regulated proteins...

  19. Is there a field-theoretic explanation for precursor biopolymers?

    Science.gov (United States)

    Rosen, Gerald

    2002-08-01

    A Hu-Barkana-Gruzinov cold dark matter scalar field phi may enter a weak isospin invariant derivative interaction that causes the flow of right-handed electrons to align parallel to (inverted delta phi). Hence, in the outer regions of galaxies where (inverted delta phi) is large, as in galactic halos, the derivative interaction may induce a chirality-imbued quantum chemistry. Such a chirality-imbued chemistry would in turn be conducive to the formation of abundant precursor biopolymers on interstellar dust grains, comets and meteors in galactic halo regions, with subsequent delivery to planets in the inner galactic regions where phi and (inverted delta phi) are concomitantly near zero and left-right symmetric terrestrial quantum chemistry prevails.

  20. Metaplasia in the Stomach-Precursor of Gastric Cancer?

    Science.gov (United States)

    Kinoshita, Hiroto; Hayakawa, Yoku; Koike, Kazuhiko

    2017-09-27

    Despite a significant decrease in the incidence of gastric cancer in Western countries over the past century, gastric cancer is still one of the leading causes of cancer-related deaths worldwide. Most human gastric cancers develop after long-term Helicobacter pylori infection via the Correa pathway: the progression is from gastritis, atrophy, intestinal metaplasia, dysplasia, to cancer. However, it remains unclear whether metaplasia is a direct precursor of gastric cancer or merely a marker of high cancer risk. Here, we review human studies on the relationship between metaplasia and cancer in the stomach, data from mouse models of metaplasia regarding the mechanism of metaplasia development, and the cellular responses induced by H. pylori infection.

  1. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    Science.gov (United States)

    Cai, Yuxuan

    Superhydrophobic surfaces exhibit superior water repellent properties, and they have remarkable potential to improve current energy infrastructure. Substantial research has been performed on the production of superhydrophobic coatings. However, superhydrophobic coatings have not yet been adopted in many industries where potential applications exist due to the limited durability of the coating materials and the complex and costly fabrication processes. Here presented a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature and strong mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The as-sprayed coating demonstrated a hierarchically structured coating topography, which closely resembles superhydrophobic surfaces in nature. Compared to smooth REO surfaces, the SPPS superhydrophobic coating improved the water contact angle by as much as 65° after vacuum treatment at 1 Pa for 48 hours.

  2. Tilt Precursors before Earthquakes on the San Andreas Fault, California.

    Science.gov (United States)

    Johnston, M J; Mortensen, C E

    1974-12-13

    An array of 14 biaxial shallow-borehole tiltmeters (at 1O(-7) radian sensitivity) has been installed along 85 kilometers of the San Andreas fault during the past year. Earthquake-related changes in tilt have been simultaneously observed on up to four independent instruments. At earthquake distances greater than 10 earthquake source dimensions, there are few clear indications of tilt change. For the four instruments with the longest records (> 10 months), 26 earthquakes have occurred since July 1973 with at least one instrument closer than 10 source dimensions and 8 earthquakes with more than one instrument within that distance. Precursors in tilt direction have been observed before more than 10 earthquakes or groups of earthquakes, and no similar effect has yet been seen without the occurrence of an earthquake.

  3. Ground-state transcriptional requirements for skin-derived precursors.

    Science.gov (United States)

    Suflita, Michael T; Pfaltzgraff, Elise R; Mundell, Nathan A; Pevny, Larysa H; Labosky, Patricia A

    2013-06-15

    Skin-derived precursors (SKPs) are an attractive stem cell model for cell-based therapies. SKPs can be readily generated from embryonic and adult mice and adult humans, exhibit a high degree of multipotency, and have the potential to serve as a patient autologous stem cell. The advancement of these cells toward therapeutic use depends on the ability to control precisely the self-renewal and differentiation of SKPs. Here we show that two well-known stem cell factors, Foxd3 and Sox2, are critical regulators of the stem cell properties of SKPs. Deletion of Foxd3 completely abolishes the sphere-forming potential of these cells. In the absence of Sox2, SKP spheres can be formed, but with reduced size and frequency. Our results provide entry points into the gene regulatory networks dictating SKP behavior, and pave the way for future studies on a therapeutically relevant stem cell.

  4. Metaplasia in the Stomach—Precursor of Gastric Cancer?

    Directory of Open Access Journals (Sweden)

    Hiroto Kinoshita

    2017-09-01

    Full Text Available Despite a significant decrease in the incidence of gastric cancer in Western countries over the past century, gastric cancer is still one of the leading causes of cancer-related deaths worldwide. Most human gastric cancers develop after long-term Helicobacter pylori infection via the Correa pathway: the progression is from gastritis, atrophy, intestinal metaplasia, dysplasia, to cancer. However, it remains unclear whether metaplasia is a direct precursor of gastric cancer or merely a marker of high cancer risk. Here, we review human studies on the relationship between metaplasia and cancer in the stomach, data from mouse models of metaplasia regarding the mechanism of metaplasia development, and the cellular responses induced by H. pylori infection.

  5. Review of Dolomite as Precursor of Geopolymer Materials

    Directory of Open Access Journals (Sweden)

    Azimi E.A.

    2016-01-01

    Full Text Available Geopolymer is an environmentally friendly cementitious binder that does not require the existence of ordinary Portland cement (OPC. Geopolymer has many excellent advantages, including high early strength, low shrinkage, good thermal resistance and good chemical resistance. Previous commonly used materials include fly ash, clay and slag. The used of dolomite as precursor material in geopolymer field is still new and at the early stage of study. Only a few researchers have done studies on dolomite in geopolymer. Dolomite (CaMg(CO32 is abundant and generally inexpensive natural minerals. The possible use of these bulk calcium carbonate materials in improving the mechanical properties of geopolymers will therefore be of great interest. This paper summarizes some research outcomes on dolomite in geopolymer along with the potential of dolomite as geopolymer composites.

  6. Low frequency sawtooth precursor activity in ASDEX Upgrade

    International Nuclear Information System (INIS)

    Papp, G; Pokol, G I; Por, G; Magyarkuti, A; Lazanyi, N; Horvath, L; Igochine, V; Maraschek, M

    2011-01-01

    This paper describes the precursor activity observed in the ASDEX Upgrade tokamak before sawtooth crashes in various neutral beam heated plasmas, utilizing the soft x-ray diagnostic. In addition to the well-known (m, n) = (1,1) internal kink mode and its harmonics, a lower frequency mode is studied in detail. Power modulation of this mode is found to correlate with the power modulation of the (1, 1) kink mode in the quasistationary intervals indicating possible nonlinear interaction. Throughout the studied sawtooth crashes, the power of the lower frequency mode rose by several orders of magnitude just before the crash. In addition to its temporal behaviour, its spatial structure was estimated and the most likely value was found to be (1, 1). A possible role of this mode in the mechanism of the sawtooth crash is discussed.

  7. The Fe/Mn constraint on precursors of basaltic achondrites

    Science.gov (United States)

    Delaney, Jeremy S.; Boesenberg, Joseph S.

    1993-01-01

    Most achondritic meteorites have Fe/Mn ratios that are lower than those of carbonaceous chondrites and of course are lower than the solar system abundance ratio of these elements. Models of the origin of achondritic assemblages must, therefore, account for these ratios. Fe/Mn ratios are suggested to be distinctive for samples from each achondrite parent body and for the Earth and Moon, but the correspondence between the Fe/Mn systematics of achondrites and chondritic precursors is unclear. Most models of achondrite genesis involve magmatic differentiation of chondritic precursors. The Fe/Mn difference between achondrites and chondrites is particularly significant since Fe and Mn are geochemically similar elements with similar partitioning behavior in familiar magmatic systems and are generally coupled during crystal-liquid fractionation. In contrast, however, Mn is more volatile than Fe in a nebular setting. Variation of Fe/Mn ratios based on the relative volatility of these elements in the early nebula provides a constraint for models by which the basaltic achondrites (with Fe/Mn ratios approximately = 25-50) are derived from mixtures of nebular components that were enriched in volatile components such as Mn. However, such volatile enriched components have not been identified in chondrites. When the abundance in achondrites of elements of similar volatility is examined, anomalies appear. For example, Na is massively depleted in basaltic achondrites when compared to Mn. These anomalies might be explained using current models but the alternative hypothesis, that Fe/Mn ratio is controlled not by nebular volatility constraints, but by planetary differentiation should be explored.

  8. Using Groundwater physiochemical properties for assessing potential earthquake precursor

    Science.gov (United States)

    Inbar, Nimrod; Reuveni, Yuval; Anker, Yaakov; Guttman, Joseph

    2017-04-01

    Worldwide studies reports pre-seismic, co-seismic and post-seismic reaction of groundwater to earthquakes. The unique hydrological and geological situation in Israel resulted in relatively deep water wells which are located close to seismically active tectonic plate boundary. Moreover, the Israeli experience show that anomalies may occurs 60-90 minutes prior to the seismic event (Guttman et al., 2005; Anker et al., 2016). Here, we try to assess the possible connection between changes in physiochemical parameters of groundwater and earthquakes along the Dead Sea Transform (DST) region. A designated network of monitoring stations was installed in MEKOROT abandoned deep water wells, continuously measuring water table, conductivity and temperature at a sampling rate of 1 minute. Preliminary analysis compares changes in the measured parameters with rain events, tidal effects and earthquake occurrences of all measured magnitudes (>2.5Md) at monitoring area surroundings. The acquired data set over one year recorded simultaneous abrupt changes in several wells which seems disconnected from standard hydrological occurrences such as precipitation, abstraction or tidal effects. At this stage, our research aims to determine and rationalize a baseline for "normal response" of the measured parameters to external occurrences while isolating those cases in which "deviations" from that base line is recorded. We apply several analysis techniques both in time and frequency domain with the measured signal as well as statistical analysis of several measured earthquake parameters, which indicate potential correlations between earthquakes occurrences and the measured signal. We show that at least in one seismic event (5.1 Md) a potential precursor may have been recorded. Reference: Anker, Y., N. Inbar, A. Y. Dror, Y. Reuveni, J. Guttman, A. Flexer, (2016). Groundwater response to ground movements, as a tool for earthquakes monitoring and a possible precursor. 8th International Conference

  9. JAK/Stat signaling regulates heart precursor diversification in Drosophila

    Science.gov (United States)

    Johnson, Aaron N.; Mokalled, Mayssa H.; Haden, Tom N.; Olson, Eric N.

    2011-01-01

    Intercellular signal transduction pathways regulate the NK-2 family of transcription factors in a conserved gene regulatory network that directs cardiogenesis in both flies and mammals. The Drosophila NK-2 protein Tinman (Tin) was recently shown to regulate Stat92E, the Janus kinase (JAK) and Signal transducer and activator of transcription (Stat) pathway effector, in the developing mesoderm. To understand whether the JAK/Stat pathway also regulates cardiogenesis, we performed a systematic characterization of JAK/Stat signaling during mesoderm development. Drosophila embryos with mutations in the JAK/Stat ligand upd or in Stat92E have non-functional hearts with luminal defects and inappropriate cell aggregations. Using strong Stat92E loss-of-function alleles, we show that the JAK/Stat pathway regulates tin expression prior to heart precursor cell diversification. tin expression can be subdivided into four phases and, in Stat92E mutant embryos, the broad phase 2 expression pattern in the dorsal mesoderm does not restrict to the constrained phase 3 pattern. These embryos also have an expanded pericardial cell domain. We show the E(spl)-C gene HLHm5 is expressed in a pattern complementary to tin during phase 3 and that this expression is JAK/Stat dependent. In addition, E(spl)-C mutant embryos phenocopy the cardiac defects of Stat92E embryos. Mechanistically, JAK/Stat signals activate E(spl)-C genes to restrict Tin expression and the subsequent expression of the T-box transcription factor H15 to direct heart precursor diversification. This study is the first to characterize a role for the JAK/Stat pathway during cardiogenesis and identifies an autoregulatory circuit in which tin limits its own expression domain. PMID:21965617

  10. First results on GlioLab/GlioSat Precursors Missions

    Science.gov (United States)

    Cappelletti, Chantal; Notarangelo, Angelo; Demoss, Darrin; Carella, Massimo

    2012-07-01

    Since 2009 GAUSS group is involved in a joint collaboration with Morehead State University (MSU) Space Science Center and IRCCS Casa Sollievo della Sofferenza (CSS) research labs with the aim to design a biomedical project in order to investigate if the combined effects of microgravity conditions and ionizing radiation increase or decrease the survival rate of cancer cells. The biological sample consists of Glioblastoma cancer cell line ANGM-CSS. Glioblastoma is a kind of cancer that can be treated after surgery only by radiotherapy using ionizing radiation. This treatment, anyway, results in a very low survival rate. This project uses different university space platforms: a CubeLab, named GlioLab, on board the International Space Station and the university microsatellite UniSat-5 designed by GAUSS. In addition a GlioLab/GlioSat precursor experiment has already flown two times with the Space Shuttle during the missions STS-134 and STS-135. The phase 0 or the precursor of GlioLab uses a COTS system, named Liquid Mixing Apparatus (LMA), to board the biological samples inside the Space Shuttle for thirty day . The LMA allows to board liquids inside a vial but is not equipped with environment control system. After landing the samples were investigated by researchers at CSS in Italy and at MSU in Kentucky. This paper deals with the experimental set up and the results obtained during the STS-134 and STS-135 missions and with the new evidences on the behavior of this kind of cancer. In particular the results obtained on the DNA analysis give a confirmation of the original idea of GLioLab/Gliosat project justifying the development of the two systems.

  11. Airborne Nicotine, Secondhand Smoke, and Precursors to Adolescent Smoking.

    Science.gov (United States)

    McGrath, Jennifer J; Racicot, Simon; Okoli, Chizimuzo T C; Hammond, S Katharine; O'Loughlin, Jennifer

    2018-01-01

    Secondhand smoke (SHS) directly increases exposure to airborne nicotine, tobacco's main psychoactive substance. When exposed to SHS, nonsmokers inhale 60% to 80% of airborne nicotine, absorb concentrations similar to those absorbed by smokers, and display high levels of nicotine biomarkers. Social modeling, or observing other smokers, is a well-established predictor of smoking during adolescence. Observing smokers also leads to increased pharmacological exposure to airborne nicotine via SHS. The objective of this study is to investigate whether greater exposure to airborne nicotine via SHS increases the risk for smoking initiation precursors among never-smoking adolescents. Secondary students ( N = 406; never-smokers: n = 338, 53% girls, mean age = 12.9, SD = 0.4) participated in the AdoQuest II longitudinal cohort. They answered questionnaires about social exposure to smoking (parents, siblings, peers) and known smoking precursors (eg, expected benefits and/or costs, SHS aversion, smoking susceptibility, and nicotine dependence symptoms). Saliva and hair samples were collected to derive biomarkers of cotinine and nicotine. Adolescents wore a passive monitor for 1 week to measure airborne nicotine. Higher airborne nicotine was significantly associated with greater expected benefits ( R 2 = 0.024) and lower expected costs ( R 2 = 0.014). Higher social exposure was significantly associated with more temptation to try smoking ( R 2 = 0.025), lower aversion to SHS ( R 2 = 0.038), and greater smoking susceptibility ( R 2 = 0.071). Greater social exposure was significantly associated with more nicotine dependence symptoms; this relation worsened with higher nicotine exposure (cotinine R 2 = 0.096; airborne nicotine R 2 = 0.088). Airborne nicotine exposure via SHS is a plausible risk factor for smoking initiation during adolescence. Public health implications include limiting airborne nicotine through smoking bans in homes and cars, in addition to stringent restrictions

  12. Non-invasive method for in vivo detection of chlorophyll precursors

    DEFF Research Database (Denmark)

    Kristiansen, Kim Anker; Khrouchtchova, Anastassia; Stenbæk, Anne

    2009-01-01

    Traditionally chlorophyll (Chl) and Chl precursors have been studied in vitro or in leaf tissue at low temperature. These methods are destructive and make it impossible to work with the same individual plant later on. In this paper we present a method for in vivo detection of Chl and its precursors...... is compared to current methods. Furthermore, we report on optimization of the spectral scanning method with the aim to minimize the excitation light-evoked photo-conversion of the chlorophyll precursors....

  13. Method to determine the sticking coefficient of precursor molecules in atomic layer deposition

    International Nuclear Information System (INIS)

    Rose, M.; Bartha, J.W.

    2009-01-01

    A method to determine the sticking coefficient of precursor molecules used in atomic layer deposition (ALD) will be introduced. The sticking coefficient is an interesting quantity for comparing different ALD processes and reactors but it cannot be observed easily. The method relies on free molecular flow in nanoscale cylindrical holes. The sticking coefficient is determined for tetrakis(dimethylamino)titanium in combination with ozone. The proposed method can be applied independent of the type of reactor, precursor delivery system and precursors.

  14. PSA-NCAM-Negative Neural Crest Cells Emerging during Neural Induction of Pluripotent Stem Cells Cause Mesodermal Tumors and Unwanted Grafts

    Science.gov (United States)

    Lee, Dongjin R.; Yoo, Jeong-Eun; Lee, Jae Souk; Park, Sanghyun; Lee, Junwon; Park, Chul-Yong; Ji, Eunhyun; Kim, Han-Soo; Hwang, Dong-Youn; Kim, Dae-Sung; Kim, Dong-Wook

    2015-01-01

    Summary Tumorigenic potential of human pluripotent stem cells (hPSCs) is an important issue in clinical applications. Despite many efforts, PSC-derived neural precursor cells (NPCs) have repeatedly induced tumors in animal models even though pluripotent cells were not detected. We found that polysialic acid-neural cell adhesion molecule (PSA-NCAM)− cells among the early NPCs caused tumors, whereas PSA-NCAM+ cells were nontumorigenic. Molecular profiling, global gene analysis, and multilineage differentiation of PSA-NCAM− cells confirm that they are multipotent neural crest stem cells (NCSCs) that could differentiate into both ectodermal and mesodermal lineages. Transplantation of PSA-NCAM− cells in a gradient manner mixed with PSA-NCAM+ cells proportionally increased mesodermal tumor formation and unwanted grafts such as PERIPHERIN+ cells or pigmented cells in the rat brain. Therefore, we suggest that NCSCs are a critical target for tumor prevention in hPSC-derived NPCs, and removal of PSA-NCAM− cells eliminates the tumorigenic potential originating from NCSCs after transplantation. PMID:25937368

  15. Unique Preservation of Neural Cells in Hutchinson- Gilford Progeria Syndrome Is Due to the Expression of the Neural-Specific miR-9 MicroRNA

    Directory of Open Access Journals (Sweden)

    Xavier Nissan

    2012-07-01

    Full Text Available One puzzling observation in patients affected with Hutchinson-Gilford progeria syndrome (HGPS, who overall exhibit systemic and dramatic premature aging, is the absence of any conspicuous cognitive impairment. Recent studies based on induced pluripotent stem cells derived from HGPS patient cells have revealed a lack of expression in neural derivatives of lamin A, a major isoform of LMNA that is initially produced as a precursor called prelamin A. In HGPS, defective maturation of a mutated prelamin A induces the accumulation of toxic progerin in patient cells. Here, we show that a microRNA, miR-9, negatively controls lamin A and progerin expression in neural cells. This may bear major functional correlates, as alleviation of nuclear blebbing is observed in nonneural cells after miR-9 overexpression. Our results support the hypothesis, recently proposed from analyses in mice, that protection of neural cells from progerin accumulation in HGPS is due to the physiologically restricted expression of miR-9 to that cell lineage.

  16. Natural attenuation of NDMA precursors in an urban, wastewater-dominated wash.

    Science.gov (United States)

    Woods, Gwen C; Dickenson, Eric R V

    2016-02-01

    N-Nitrosodimethylamine (NDMA) is a disinfection by-product (DBP) that is potentially carcinogenic and has been found to occur in drinking water treatment systems impacted with treated wastewater. A major gap in NDMA research is an understanding of the persistence of wastewater-derived precursors within the natural environment. This research sought to fill this knowledge gap by surveying NDMA precursors across the length of a wastewater effluent-dominated wash. Significant precursor reduction (17%) was found to occur from introduction into the wash to a point 9 h downstream. This reduction translates into a half-life of roughly 32 h for bulk NDMA precursors. Further laboratory experiments examining rates of photolysis, biodegradation and loss to sediments, illustrated that both photolytic and biological degradation were effective removal mechanisms for NDMA precursors. Loss to sediments that were acquired from the wash did not appear to reduce NDMA precursors in the water column, although a control conducted with DI water provided evidence that significant NDMA precursors could be released from autoclaved sediments (suggesting that sorption does occur). Microbial experiments revealed that microbes associated with sediments were much more effective at degrading precursors than microbes within the water column. Overall, this study demonstrated that natural processes are capable of attenuating NDMA precursors relatively quickly within the environment, and that utilities might benefit from maximizing source water residency time in the environment, prior to introduction into treatment plants. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Controlled Growth of ZnSe Nanocrystals by Tuning Reactivity and Amount of Zinc Precursor

    Directory of Open Access Journals (Sweden)

    Lai-Jun Zhang

    2013-01-01

    Full Text Available Zinc selenide (ZnSe nanocrystals were synthesized via a phosphine-free route using the highly reactive alkylamine-H2Se complex as selenium precursor and zinc precursors with different reactivity. The reactivity of zinc precursor was tuned by using three kinds of zinc carboxylates with different alkyl chain lengths, including zinc acetate, zinc nonanoate, and zinc stearate. The effect of the reactivity and the amount of zinc precursor on nucleation and growth of ZnSe nanocrystals were investigated by ultraviolet-visible absorption and photoluminescence spectra. Result indicates that the growth and optical property of the resulting ZnSe nanocrystals are strongly dependent on the alkyl chain length and the amount of the zinc carboxylates and both shorter alkyl chain length, and more amount of zinc carboxylate will lead to faster growth of ZnSe nanocrystals. This allows that the controlled growth and excellent optical property of high-quality ZnSe nanocrystals can be achieved by combining the different reactivity and the used amount of zinc precursor, such as by using stoichiometric and reactive Zn precursor and Se precursor or by using larger amount of more unreactive Zn precursor relative to the highly reactive alkylamine-H2Se complex precursor.

  18. Spike Neural Models Part II: Abstract Neural Models

    Directory of Open Access Journals (Sweden)

    Johnson, Melissa G.

    2018-02-01

    Full Text Available Neurons are complex cells that require a lot of time and resources to model completely. In spiking neural networks (SNN though, not all that complexity is required. Therefore simple, abstract models are often used. These models save time, use less computer resources, and are easier to understand. This tutorial presents two such models: Izhikevich's model, which is biologically realistic in the resulting spike trains but not in the parameters, and the Leaky Integrate and Fire (LIF model which is not biologically realistic but does quickly and easily integrate input to produce spikes. Izhikevich's model is based on Hodgkin-Huxley's model but simplified such that it uses only two differentiation equations and four parameters to produce various realistic spike patterns. LIF is based on a standard electrical circuit and contains one equation. Either of these two models, or any of the many other models in literature can be used in a SNN. Choosing a neural model is an important task that depends on the goal of the research and the resources available. Once a model is chosen, network decisions such as connectivity, delay, and sparseness, need to be made. Understanding neural models and how they are incorporated into the network is the first step in creating a SNN.

  19. Summary of ceramic pigments by polymer precursors Pechini method; Sintese de pigmentos ceramicos pelo metodo dos precursores polimericos

    Energy Technology Data Exchange (ETDEWEB)

    Silva, E.M. da; Galvao, S.B.; Paskocimas, C.A., E-mail: everlania_siva@yahoo.com.b [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2010-07-01

    In this work were synthesized nitrate chromium nitrate and iron-doped titanium oxide by the polymeric precursor method, for application as ceramic pigments. The stains were developed between the temperatures 700 deg C to 1000 deg C, in green for chromium oxide and orange for iron. Noticing an increase of its opacity by increasing temperature. Characterization by thermogravimetry (TG) showed strong thermo decomposition from 355 deg C for the chromium oxide and thermo decomposition gradual for the iron. By analysis of X-ray diffraction revealed the formation of crystalline phases as Iron Titanate (FeTiO3) and Chrome Titanate (CrTiO3), respectively. The scanning electron microscopy showed the formation of rounded particles for both oxides. Thus, the synthesized oxides were within the requirements to be applied as pigments and shown to be possible to propose its use in ceramic materials. (author)

  20. Constitutively active Notch1 converts cranial neural crest-derived frontonasal mesenchyme to perivascular cells in vivo

    Directory of Open Access Journals (Sweden)

    Sophie R. Miller

    2017-03-01

    Full Text Available Perivascular/mural cells originate from either the mesoderm or the cranial neural crest. Regardless of their origin, Notch signalling is necessary for their formation. Furthermore, in both chicken and mouse, constitutive Notch1 activation (via expression of the Notch1 intracellular domain is sufficient in vivo to convert trunk mesoderm-derived somite cells to perivascular cells, at the expense of skeletal muscle. In experiments originally designed to investigate the effect of premature Notch1 activation on the development of neural crest-derived olfactory ensheathing glial cells (OECs, we used in ovo electroporation to insert a tetracycline-inducible NotchΔE construct (encoding a constitutively active mutant of mouse Notch1 into the genome of chicken cranial neural crest cell precursors, and activated NotchΔE expression by doxycycline injection at embryonic day 4. NotchΔE-targeted cells formed perivascular cells within the frontonasal mesenchyme, and expressed a perivascular marker on the olfactory nerve. Hence, constitutively activating Notch1 is sufficient in vivo to drive not only somite cells, but also neural crest-derived frontonasal mesenchyme and perhaps developing OECs, to a perivascular cell fate. These results also highlight the plasticity of neural crest-derived mesenchyme and glia.