Sample records for ca3 representations established

  1. Establishing path integral in the entangled state representation for Hamiltonians in quantum optics

    Wang Ji-Suo; Meng Xiang-Guo; Feng Jian; Gao Yun-Feng


    Based on two mutually conjugate entangled state representations, we establish the path integral formalism for some Hamiltonians of quantum optics in entangled state representations. The Wigner operator in the entangled state representation is presented. Its advantages are explained.

  2. Nonunion Worker Representation, Foreign Owners and the Performance of Establishments

    Jirjahn, Uwe; Mueller, Steffen


    Using German establishment data, this study provides the first econometric analysis on the interaction of establishment-level codetermination and foreign owners. Works councils are associated with higher productivity in domestic-owned establishments while they are associated with lower productivity in foreign-owned establishments. Moreover, the estimates show that the interaction of works councils with the broader industrial relations system also depends on the type of ownership. Works counci...

  3. Place Cell Rate Remapping by CA3 Recurrent Collaterals

    Solstad, Trygve; Yousif, Hosam N.; Sejnowski, Terrence J.


    Episodic-like memory is thought to be supported by attractor dynamics in the hippocampus. A possible neural substrate for this memory mechanism is rate remapping, in which the spatial map of place cells encodes contextual information through firing rate variability. To test whether memories are stored as multimodal attractors in populations of place cells, recent experiments morphed one familiar context into another while observing the responses of CA3 cell ensembles. Average population activity in CA3 was reported to transition gradually rather than abruptly from one familiar context to the next, suggesting a lack of attractive forces associated with the two stored representations. On the other hand, individual CA3 cells showed a mix of gradual and abrupt transitions at different points along the morph sequence, and some displayed hysteresis which is a signature of attractor dynamics. To understand whether these seemingly conflicting results are commensurate with attractor network theory, we developed a neural network model of the CA3 with attractors for both position and discrete contexts. We found that for memories stored in overlapping neural ensembles within a single spatial map, position-dependent context attractors made transitions at different points along the morph sequence. Smooth transition curves arose from averaging across the population, while a heterogeneous set of responses was observed on the single unit level. In contrast, orthogonal memories led to abrupt and coherent transitions on both population and single unit levels as experimentally observed when remapping between two independent spatial maps. Strong recurrent feedback entailed a hysteretic effect on the network which diminished with the amount of overlap in the stored memories. These results suggest that context-dependent memory can be supported by overlapping local attractors within a spatial map of CA3 place cells. Similar mechanisms for context-dependent memory may also be found in

  4. Place cell rate remapping by CA3 recurrent collaterals.

    Trygve Solstad


    Full Text Available Episodic-like memory is thought to be supported by attractor dynamics in the hippocampus. A possible neural substrate for this memory mechanism is rate remapping, in which the spatial map of place cells encodes contextual information through firing rate variability. To test whether memories are stored as multimodal attractors in populations of place cells, recent experiments morphed one familiar context into another while observing the responses of CA3 cell ensembles. Average population activity in CA3 was reported to transition gradually rather than abruptly from one familiar context to the next, suggesting a lack of attractive forces associated with the two stored representations. On the other hand, individual CA3 cells showed a mix of gradual and abrupt transitions at different points along the morph sequence, and some displayed hysteresis which is a signature of attractor dynamics. To understand whether these seemingly conflicting results are commensurate with attractor network theory, we developed a neural network model of the CA3 with attractors for both position and discrete contexts. We found that for memories stored in overlapping neural ensembles within a single spatial map, position-dependent context attractors made transitions at different points along the morph sequence. Smooth transition curves arose from averaging across the population, while a heterogeneous set of responses was observed on the single unit level. In contrast, orthogonal memories led to abrupt and coherent transitions on both population and single unit levels as experimentally observed when remapping between two independent spatial maps. Strong recurrent feedback entailed a hysteretic effect on the network which diminished with the amount of overlap in the stored memories. These results suggest that context-dependent memory can be supported by overlapping local attractors within a spatial map of CA3 place cells. Similar mechanisms for context-dependent memory may

  5. 50 CFR Appendix A to Chapter I - Codes for the Representation of Names of Countries (Established by the International Organization...


    ... 50 Wildlife and Fisheries 6 2010-10-01 2010-10-01 false Codes for the Representation of Names of Countries (Established by the International Organization for Standardization) A Appendix A to Chapter I... the International Organization for Standardization) Country 2-Letter code Afghanistan AF. Albania...

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

    Richard eMiles


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

  7. A signature of attractor dynamics in the CA3 region of the hippocampus.

    César Rennó-Costa


    Full Text Available The notion of attractor networks is the leading hypothesis for how associative memories are stored and recalled. A defining anatomical feature of such networks is excitatory recurrent connections. These "attract" the firing pattern of the network to a stored pattern, even when the external input is incomplete (pattern completion. The CA3 region of the hippocampus has been postulated to be such an attractor network; however, the experimental evidence has been ambiguous, leading to the suggestion that CA3 is not an attractor network. In order to resolve this controversy and to better understand how CA3 functions, we simulated CA3 and its input structures. In our simulation, we could reproduce critical experimental results and establish the criteria for identifying attractor properties. Notably, under conditions in which there is continuous input, the output should be "attracted" to a stored pattern. However, contrary to previous expectations, as a pattern is gradually "morphed" from one stored pattern to another, a sharp transition between output patterns is not expected. The observed firing patterns of CA3 meet these criteria and can be quantitatively accounted for by our model. Notably, as morphing proceeds, the activity pattern in the dentate gyrus changes; in contrast, the activity pattern in the downstream CA3 network is attracted to a stored pattern and thus undergoes little change. We furthermore show that other aspects of the observed firing patterns can be explained by learning that occurs during behavioral testing. The CA3 thus displays both the learning and recall signatures of an attractor network. These observations, taken together with existing anatomical and behavioral evidence, make the strong case that CA3 constructs associative memories based on attractor dynamics.

  8. Neuronal migration and its disorders affecting the CA3 region

    Richard eBelvindrah


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

  9. Oxygen potentials and phase equilibria in the system Ca–Co–O and thermodynamic properties of Ca3Co2O6 and Ca3Co4O9.163

    Oxygen potentials established by the equilibrium between three condensed phases, CaOss+CoOss+Ca3Co2O6 and CoOss+Ca3Co2O6+Ca3Co3.93+αO9.36−δ, are measured as a function of temperature using solid-state electrochemical cells incorporating yttria-stabilized zirconia as the electrolyte and pure oxygen as the reference electrode. Cation non-stoichiometry and oxygen non-stoichiometry in Ca3Co3.93+αO9.36−δ are determined using different techniques under defined conditions. Decomposition temperatures and thermodynamic properties of Ca3Co2O6 and Ca3Co4O9.163 are calculated from the results. The standard entropy and enthalpy of formation of Ca3Co2O6 at 298.15 K are evaluated. Using thermodynamic data from this study and auxiliary information from the literature, phase diagram for the ternary system Ca–Co–O is computed. Isothermal sections at representative temperatures are displayed to demonstrate the evolution of phase relations with temperature. - Graphical abstract: Isothermal section of the phase diagram of the system Ca–Co–O at 1250 K. - Highlights: • Improved definition of cation and oxygen nonstoichiometry of Ca3Co3.93+αO9.36−δ. • Measurement of ΔμO2 associated with two 3-phase fields as a function of temperature. • Use of solid-state electrochemical cells for accurate measurement of ΔμO2. • Decomposition temperatures and thermodynamic properties for ternary oxides. • Characterization of ternary phase diagram of the system Ca–Co–O

  10. A Hopfield-like hippocampal CA3 neural network model for studying associative memory in Alzheimer's disease

    Wangxiong Zhao; Qingli Qiao; Dan Wang


    Associative memory, one of the major cognitive functions in the hippocampal CA3 region, includes auto-associative memory and hetero-associative memory. Many previous studies have shown that Alzheimer's disease (AD) can lead to loss of functional synapses in the central nervous system, and associative memory functions in patients with AD are often impaired, but few studies have addressed the effect of AD on hetero-associative memory in the hippocampal CA3 region. In this study, based on a simplified anatomical structure and synaptic connections in the hippocampal CA3 region, a three-layered Hopfield-like neural network model of hippocampal CA3 was proposed and then used to simulate associative memory functions in three circumstances: normal, synaptic deletion and synaptic compensation, according to Ruppin's synaptic deletion and compensation theory. The influences of AD on hetero-associative memory were further analyzed. The simulated results showed that the established three-layered Hopfield-like neural network model of hippocampal CA3 has both auto-associative and hetero-associative memory functions. With increasing synaptic deletion level, both associative memory functions were gradually impaired and the mean firing rates of the neurons within the network model were decreased. With gradual increasing synaptic compensation, the associative memory functions of the network were improved and the mean firing rates were increased. The simulated results suggest that the Hopfield-like neural network model can effectively simulate both associative memory functions of the hippocampal CA3 region. Synaptic deletion affects both auto-associative and hetero-associative memory functions in the hippocampal CA3 region, and can also result in memory dysfunction. To some extent, synaptic compensation measures can offset two kinds of associative memory dysfunction caused by synaptic deletion in the hippocampal CA3 area.

  11. Behavioral Functions of the CA3 Subregion of the Hippocampus

    Kesner, Raymond P.


    From a behavioral perspective, the CA3a,b subregion of the hippocampus plays an important role in the encoding of new spatial information within short-term memory with a duration of seconds and minutes. This can easily be observed in tasks that require rapid encoding, novelty detection, one-trial short-term or working memory, and one-trial cued…

  12. Prominent hippocampal CA3 gene expression profile in neurocognitive aging

    Haberman, Rebecca P.; Colantuoni, Carlo; Stocker, Amy M.; Schmidt, Alexandra C.; Pedersen, Jan T.; Gallagher, Michela


    Research in aging laboratory animals has characterized physiological and cellular alterations in medial temporal lobe structures, particularly the hippocampus, that are central to age-related memory deficits. The current study compares molecular alterations across hippocampal subregions in a rat model that closely mirrors individual differences in neurocognitive features of aging humans, including both impaired memory and preserved function. Using mRNA profiling of the CA1, CA3 and dentate gy...

  13. High pressure studies in Ca3Ru2O7

    The bilayer ruthenate Ca3Ru2O7 undergoes first a magnetic transition (TN=56 K) and then a structural transition (TS= 48 K) on cooling. Most of the Fermi surface is gapped out at low temperature, leading to a very low carrier density and small Fermi surface pockets. Pressure suppresses both TN and TS and, for p>3.5 GPa, induces a third low temperature state, which has been known to be robust up to at least 7.5 GPa. A detailed investigation of the unusual low temperature states of Ca3Ru2O7 across the pressure-temperature-field phase diagram requires reliable access to hydrostatic pressures up to and beyond 10 GPa. We apply lithographic patterning and sputtering processes to anvil pressure cells in order to produce complex but robust lead patterns, which are integrated into the anvil surface. Patterns include multi-turn coils as well as eight-lead configurations for resistivity measurements. Resistivity data in Ca3Ru2O7 is presented, which indicates that the high pressure ordered state is fully suppressed at pc ≅9.5 GPa. Beyond pc, the in-plane resistivity follows a T5/3 power-law down to below 1 K, suggesting ferromagnetic quantum criticality.

  14. Ca3P2 and other topological semimetals with line nodes and drumhead surface states

    Chan, Y.-H.; Chiu, Ching-Kai; Chou, M. Y.; Schnyder, Andreas P.


    As opposed to ordinary metals, whose Fermi surfaces are two dimensional, topological (semi)metals can exhibit protected one-dimensional Fermi lines or zero-dimensional Fermi points, which arise due to an intricate interplay between symmetry and topology of the electronic wave functions. Here, we study how reflection symmetry, time-reversal symmetry, SU(2) spin-rotation symmetry, and inversion symmetry lead to the topological protection of line nodes in three-dimensional semimetals. We obtain the crystalline invariants that guarantee the stability of the line nodes in the bulk and show that a quantized Berry phase leads to the appearance of protected surfaces states, which take the shape of a drumhead. By deriving a relation between the crystalline invariants and the Berry phase, we establish a direct connection between the stability of the line nodes and the drumhead surface states. Furthermore, we show that the dispersion minimum of the drumhead state leads to a Van Hove singularity in the surface density of states, which can serve as an experimental fingerprint of the topological surface state. As a representative example of a topological semimetal, we consider Ca3P2 , which has a line of Dirac nodes near the Fermi energy. The topological properties of Ca3P2 are discussed in terms of a low-energy effective theory and a tight-binding model, derived from ab initio DFT calculations. Our microscopic model for Ca3P2 shows that the drumhead surface states have a rather weak dispersion, which implies that correlation effects are enhanced at the surface of Ca3P2 .

  15. Magnetocapacitance in Ca3CoMnO6

    Kaushik, S. D.; Rayaprol, S.; Saha, J.; Mohapatra, N.; Siruguri, V.; Babu, P. D.; Patnaik, S.


    Magnetocapacitance (MC) measurements—that is, measuring capacitance as a function of temperature at constant magnetic field—has been carried out on a quasi-1D compound, Ca3CoMnO6. MC reveals the presence of a magnetodielectric effect (MDE), which in turn signals the presence of magnetoelectric coupling below the magnetic ordering temperature, TN ( = 15 K). We also observed the sign reversal of the MDE as the temperature increased from 3 to 20 K. The MDE is positive at 3 K and negative between 3 and 15 K, and it saturates to a near zero value above 15 K. The sign change of the MDE is explained in terms the spin-pair correlation of neighboring spins of Co/Mn at a given applied magnetic field H. A negative MDE signifies antiferromagnetic ordering, and a positive MDE signifies ferromagnetic/paramagnetic ordering. Neutron diffraction study reveals changes in the magnetic structure in the temperature range of 2 to 10 K. The present work brings out the possible correlation between the magnetic structure and the dielectric properties of Ca3CoMnO6.

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

    Lorena eDeuker


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

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

    Fumiaki Fukushima

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

  18. X-ray absorption and x-ray magnetic dichroism study on Ca3CoRhO6 and Ca3FeRhO6

    Burnus, T.; Hu, Z.; Wu, Hua; Cezar, J. C.; Niitaka, S.; Takagi, H.; Chang, C. F.; Brookes, N. B.; Lin, H.-J.; Jang, L. Y.; Tanaka, A.; Liang, K. S.; Chen, C. T.; Tjeng, L. H.


    By using x-ray absorption spectroscopy at the RhL2,3 , CoL2,3 , and FeL2,3 edges, we find a valence state of Co2+/Rh4+ in Ca3CoRhO6 and of Fe3+/Rh3+ in Ca3FeRhO6 . X-ray magnetic circular dichroism spectroscopy at the CoL2,3 edge of Ca3CoRhO6 reveals a giant orbital moment of about 1.7μB , which can be attributed to the occupation of the minority-spin d0d2 orbital state of the high-spin Co2+ (3d7) ions in trigonal prismatic coordination. This active role of the spin-orbit coupling explains the strong magnetocrystalline anisotropy and Ising-type magnetism of Ca3CoRhO6 .

  19. Structural aspects of calcium ion transport in Ca3(VO4)2 and Ca3-xNd2x/3(VO4)2 solid solutions

    Experimental data on electric conductivity dependence on temperature in the range of 750-1400 K for Ca3(VO4)2, Ca9Nd(VO4)7 and solid solutions Ca3-xNd2x/3(VO4)2 (0≤x≤3/7) are presented. It is ascertained that conductivity value in the solid solutions decreases essentially with increase in neodymium concentration. In Ca3(VO4)2 and Ca9Nd(VO4)7 phase transitions at 1383 and 1198 K have been detected. On the basis of the experimental data on conductivity and analysis of polyhedrons of whitlockite-like structure of Ca3(VO4)2 possible ways of calcium cations movement in the structure are discussed and substantiated

  20. Representational Machines

    Petersson, Dag; Dahlgren, Anna; Vestberg, Nina Lager

    Photography not only represents space. Space is produced photographically. Since its inception in the 19th century, photography has brought to light a vast array of represented subjects. Always situated in some spatial order, photographic representations have been operatively underpinned by social......, technical, and institutional mechanisms. Geographically, bodily, and geometrically, the camera has positioned its subjects in social structures and hierarchies, in recognizable localities, and in iconic depth constructions which, although they show remarkable variation, nevertheless belong specifically to...... the enterprises of the medium. This is the subject of Representational Machines: How photography enlists the workings of institutional technologies in search of establishing new iconic and social spaces. Together, the contributions to this edited volume span historical epochs, social environments...

  1. Phases of variable composition in the Ca3(VO4)2-NdVO4 - Na3VO4 system

    Phase equilibriums in the Ca3(VO4)2 - NdVO4-Na3VO4 system are studied. Formation of variable composition phases on the base of calcium orthovanadate is established. The field of variable composition phase is placed inside of Ca3(VO4)2 - Ca9Nd□(VO4)7 - Ca10Na(VO4)7 - Ca8NdNa2(VO4)7 (Z = 6) quadrangle. Boundary compositions are determined by structure of low temperature modification of Ca3(VO4)2 (Z = 21, sp. gr. R3c). The degree of Ca(4) positions occupancy has influence on phase transition temperature, ionic conductivity and parameters of IR- and CS-spectra. Considerable growth of the conductivity higher than 650 K on the calcium ions is explained by order-disorder transformation associated with disproportional of structural vacancies (□) on different cation positions

  2. X-ray absorption and x-ray magnetic dichroism study on Ca3CoRhO6 and Ca3FeRhO6

    Burnus, T.; Z. Hu; Wu, Hua; Cezar, J. C.; Niitaka, S.; Takagi, H.; Chang, C. F.; Brookes, N. B.; Lin, H. -J.; Jang, L. Y.; Tanaka, A.; Liang, K. S.; Chen, C. T.; Tjeng, L. H.


    Using x-ray absorption spectroscopy at the Rh-L_2,3, Co-L_2,3, and Fe-L_2,3 edges, we find a valence state of Co^2+/Rh^4+ in Ca3CoRhO6 and of Fe^3+/Rh^3+ in Ca3FeRhO6. X-ray magnetic circular dichroism spectroscopy at the Co-L_2,3 edge of Ca3CoRhO6 reveals a giant orbital moment of about 1.7mu_B, which can be attributed to the occupation of the minority-spin d_0d_2 orbital state of the high-spin Co^2+ (3d^7) ions in trigonal prismatic coordination. This active role of the spin-orbit coupling ...


    YAN Bing; XU Neng-gui; HE Li-lei; TANG Chun-zhi; SHAO Ying


    Objective: To observe the effect of electroacupuncture (EA) on learning and memory abilities and ultrastructure of synapses in CA3 region of the hippocampus in vascular dementia (VD) rats. Methods: A total of 32 SD rats were randomized into control (sham-operation, n = 7), model (n = 7), EA (n = 9) and medication (n=9) groups. VD model was established by occlusion of the bilateral vertebral arteries (electrocoagulation) and bilateral common carotid arteries (occlusion for 5 min and reperfusion for 10 min, repeated the procedure for 3 times to induce global ischemia). EA (150 Hz, 1 mA) was applied to "Baihui"(百会GV 20), "Geshu"(膈俞 BL 17), "Pishu"(脾俞 BL 20) and "Shenshu"(肾俞 BL 23) for 20 min, once daily and continuously for 15 days. In medication group, the rats were fed with Nimotong (12 mg/kg), once daily and continuously for 15 days. Morris water maze method was used to test the animals' learning and memory abilities (latencies to find the hidden platform determined by place navigation trials, and latencies to cross on the location of the removed platform determined by spatial probe trials) after the treatment. Ultrastructural changes (numerical density, NA,surface density, Sv and volume density, Vv) of Gray type 1 synapses in CA3 region of the hippocampus were observed by using transmission electronic microscope and automatic image analysis system. Results: 1 ) Place navigation test showed that in comparison with control group, the average escape latency of VD group was significantly longer (P<0.01), while in comparison with VD group, the latencies of both EA and medication groups decreased significantly ( P<0.01 ). No significant difference was found between EA and medication groups in the escape latency (P>0.05). 2) Spatial probe-test displayed that in comparison with control group, the times which the animals crossed the target platform in VD group decreased significantly (P<0.01), while compared with VD group, those of both EA and

  4. Frequency dependence of CA3 spike phase response arising from h-current properties

    Hyun Jae Jang


    Full Text Available The phase of firing of hippocampal neurons during theta oscillations encodes spatial information. Moreover, the spike phase response to synaptic inputs in individual cells depends on the expression of the hyperpolarisation-activated mixed cation current (Ih, which differs between CA3 and CA1 pyramidal neurons. Here, we compared the phase response of these two cell types, as well as their intrinsic membrane properties. We found that both CA3 and CA1 pyramidal neurons show a voltage sag in response to negative current steps but that this voltage sag is significantly smaller in CA3 cells. Moreover, CA3 pyramidal neurons have less prominent resonance properties compared to CA1 pyramidal neurons. This is consistent with differential expression of Ih by the two cell types. Despite their distinct intrinsic membrane properties, both CA3 and CA1 pyramidal neurons displayed bidirectional spike phase control by excitatory conductance inputs during theta oscillations. In particular, excitatory inputs delivered at the descending phase of a dynamic clamp-induced membrane potential oscillation delayed the subsequent spike by nearly 50 mrad. The effect was shown to be mediated by Ih and was counteracted by increasing inhibitory conductance driving the membrane potential oscillation. Using our experimental data to feed a computational model, we showed that differences in Ih between CA3 and CA1 pyramidal neurons could predict frequency-dependent differences in phase response properties between these cell types. We confirmed experimentally such frequency-dependent spike phase control in CA3 neurons. Therefore, a decrease in theta frequency, which is observed in intact animals during novelty, might switch the CA3 spike phase response from unidirectional to bidirectional and thereby promote encoding of the new context.

  5. Jumlah Sel Piramidal CA3 Hipokampus Tikus Putih Jantan pada Berbagai Model Stres Kerja Kronik

    Fitranto Arjadi; Sri Kadarsih Soejono; Lientje Setyawati Maurits; Mulyoto Pangestu


    Prolonged and chronic exposure to stress leads to the loss of neurons at the CA3 (cornu ammonis) hippocampus region and spatial memory deficits. The aim of this study was to study the number of CA3 pyramidal cells in albino rats that were exposed to chronic stress of works model consisting of paradoxical sleep deprivation (PSD), immobilization, and foot shock stresses. The method applied was the post-test only method with control group experimental design using completed randomized design (CR...

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

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

  7. The nature of spin trimer in Ca3Cu2Ni(PO4)4

    The nature of spin trimer and 3d spin dynamics in Ca3Cu2Ni(PO4)4 was studied using 31P NMR measurements. This material is obtained replacing one of the Cu ions by a Ni ion in one dimensional spin trimer compound Ca3Cu3(PO4)4. NMR spectrum suggests the presence of two types of magnetically inequivalent phosphorous atoms as in the parent compound. This finding reveals the presence of only one type of trimer viz. Cu2-Cu1-Cu2 rather than three types viz., Cu2-Cu1-Cu2, Cu2-Cu1-Ni and Ni-Cu1-Ni as suggested from neutron scattering. Hence the ground state of Ca3Cu2Ni(PO4)4 appears to be a quintet. The present finding also explains the magnetic susceptibility behavior showing no indication of the reduction of net spin of a trimer in Ca3Cu2Ni(PO4)4, as expected for JNi-Cu = - 0.85 meV compared to JCu-Cu = - 4.74 meV, reported from neutron scattering. The spin lattice relaxation rate suggests that the three magnon mediated scattering process, dominant in Ca3Cu3(PO4)4, is reduced in Ca3Cu2Ni(PO4)4.

  8. Presynaptic size of associational/commissural CA3 synapses is controlled by fibroblast growth factor 22 in adult mice.

    Pasaoglu, Taliha; Schikorski, Thomas


    Associational/commissural CA3-CA3 synapses define the recurrent CA3 network that generates the input to CA1 pyramidal neurons. We quantified the fine structure of excitatory synapses in the stratum radiatum of the CA3d area in adult wild type (WT) and fibroblast growth factor 22 knock-out (FGF22KO) mice by using serial 3D electron microscopy. WT excitatory CA3 synapses are rather small yet range 10 fold in size. Spine size, however, was small and uniform and did not correlate with the size of the synaptic junction. To reveal mechanisms that regulate presynaptic structure, we investigated the role of FGF22, a target-derived signal specific for the distal part of area CA3 (CA3d). In adult FGF22KO mice, postsynaptic properties of associational CA3 synapses were unaltered. Presynaptically, the number of synaptic vesicles (SVs), the bouton volume, and the number of vesicles in axonal regions (the super pool) were reduced. This concurrent decrease suggests concerted control by FGF22 of presynaptic size. This hypothesis is supported by the finding that WT presynapses in the proximal part of area CA3 (CA3p) that do not receive FGF22 signaling in WT mice were smaller than presynapses in CA3d in WT but of comparable size in CA3d of FGF22KO mice. Docked SV density was decreased in CA1, CA3d, and CA3p in FGF22KO mice. Because CA1 and CA3p are not directly affected by the loss of FGF22, the smaller docked SV density may be an adaptation to activity changes in the CA3 network. Thus, docked SV density potentially is a long-term regulator for the synaptic release probability and/or the strength of short-term depression in vivo. PMID:26222899

  9. Toward a self-wired active reconstruction of the hippocampal trisynaptic loop: DG-CA3

    Gregory J. Brewer


    Full Text Available The mammalian hippocampus functions to encode and retrieve memories by transiently changing synaptic strengths, yet encoding in individual subregions for transmission between regions remains poorly understood. Toward the goal of better understanding the coding in the trisynaptic pathway from the dentate gyrus (DG to the CA3 and CA1, we report a novel microfabricated device that divides a micro-electrode array into two compartments of separate hippocampal network subregions connected by axons that grow through 3x10x400 μm tunnels. Gene expression by qPCR demonstrated selective enrichment of separate DG, CA3 and CA1 subregions. Reconnection of DG to CA3 altered burst dynamics associated with marked enrichment of GAD67 in DG and GFAP in CA3. Surprisingly, DG axon spike propagation was preferentially unidirectional to the CA3 region at 0.5 m/s with little reverse transmission. Therefore, select hippocampal subregions intrinsically self-wire in anatomically appropriate patterns and maintain their distinct subregion phenotype without external inputs

  10. Thermodynamic stability of Ca3TeO6 determined by a solid electrolyte EMF method

    Highlights: • Gibbs energy of formation of Ca3TeO6 experimentally determined for the first time. • Oxygen concentration galvanic cells based on YSZ solid electrolyte were employed. • In the Ca–Te–O system, Ca3TeO6 coexists with CaO and Te. - Abstract: The standard thermodynamic properties of Ca3TeO6 were determined electrochemically utilizing fast O2− ion conducting solid electrolyte yttria-stabilized zirconia. The ternary phase was synthesized from the pure oxides CaO and TeO2 in excess of CaO. The electromotive force measurements were performed on two similar electrochemical cells of the type Te + CaO + Ca3TeO6|YSZ|O2, within the temperature range from 850 to 949 K. The standard Gibbs energy of formation for the ternary compound Ca3TeO6 was determined for the first time, based on the experimental data obtained

  11. Gap junctions between CA3 pyramidal cells contribute to network synchronization in neonatal hippocampus.

    Molchanova, Svetlana M; Huupponen, Johanna; Lauri, Sari E; Taira, Tomi


    Direct electrical coupling between neurons through gap junctions is prominent during development, when synaptic connectivity is scarce, providing the additional intercellular connectivity. However, functional studies of gap junctions are hampered by the unspecificity of pharmacological tools available. Here we have investigated gap-junctional coupling between CA3 pyramidal cells in neonatal hippocampus and its contribution to early network activity. Four different gap junction inhibitors, including the general blocker carbenoxolone, decreased the frequency of network activity bursts in CA3 area of hippocampus of P3-6 rats, suggesting the involvement of electrical connections in the generation of spontaneous network activity. In CA3 pyramidal cells, spikelets evoked by local stimulation of stratum oriens, were inhibited by carbenoxolone, but not by inhibitors of glutamatergic and GABAergic synaptic transmission, signifying the presence of electrical connectivity through axo-axonic gap junctions. Carbenoxolone also decreased the success rate of firing antidromic action potentials in response to stimulation, and changed the pattern of spontaneous action potential firing of CA3 pyramidal cells. Altogether, these data suggest that electrical coupling of CA3 pyramidal cells contribute to the generation of the early network events in neonatal hippocampus by modulating their firing pattern and synchronization. PMID:26926429

  12. System Ca3(VO4)2-Na3VO4-LaVO4

    Using the method of x-ray phase analysis, the phase equilibria in the system Ca3(VO4)2-Na3VO4-LaVO4 were studied. An extensive solid solution in calcium orthovanadate bounded by the compositions Ca3(VO4)2-Ca9La(VO4)7-Ca10Na(VO4)7-Ca8.5Na1.75La0.75(V)4)7 was found. The unit cell parameters of whitlockite vanadates increase with a rise in the sodium or lanthanum concentration. Ferroelectric phase transitions in Ca3-3xLa2x(VO4)2 vanadates were studied using thermal analysis, electrical conductivity measurements, and dielectric constant measurements

  13. A new form of Ca3P2 with a ring of Dirac nodes

    We report the synthesis and crystal structure of a new high-temperature form of Ca3P2. The crystal structure was determined through Rietveld refinements of synchrotron powder x-ray diffraction data. This form of Ca3P2 has a crystal structure of the hexagonal Mn5Si3 type, with a Ca ion deficiency compared to the ideal 5:3 stoichiometry. This yields a stable, charge-balanced compound of Ca2+ and P3−. We also report the observation of a secondary hydride phase, Ca5P3H, which again is a charge-balanced compound. The calculated band structure of Ca3P2 indicates that it is a three-dimensional Dirac semimetal with a highly unusual ring of Dirac nodes at the Fermi level. The Dirac states are protected against gap opening by a mirror plane in a manner analogous to what is seen for graphene

  14. Jumlah Sel Piramidal CA3 Hipokampus Tikus Putih Jantan pada Berbagai Model Stres Kerja Kronik

    Fitranto Arjadi


    Full Text Available Prolonged and chronic exposure to stress leads to the loss of neurons at the CA3 (cornu ammonis hippocampus region and spatial memory deficits. The aim of this study was to study the number of CA3 pyramidal cells in albino rats that were exposed to chronic stress of works model consisting of paradoxical sleep deprivation (PSD, immobilization, and foot shock stresses. The method applied was the post-test only method with control group experimental design using completed randomized design (CRD on 24 3–4 month old male Wistar rats. The rats were divided into 4 groups: group I (control, group II (PSD stress, group III (immobilization stress, and group IV (footshock stress. The CA3 pyramidal cell hippocampus was stained with toluidine-blue. The number of CA3 pyramidal cell of hippocampus was counted using Image raster v2.1 software at 400x magnification in 10 duplicates for each sample. The study was conducted in six months (April–September 2012 at the Animal Laboratory, Faculty of Medical and Health Sciences, Jenderal Soedirman University. Analysis for the differences in the number of CA3 pyramidal cells was conducted using analysis of variance (ANOVA with Post-Hoc LSD. The results of the ANOVA showed a p value=0.037, meaning that there was significant difference in at least two groups of treatment. Further statistical test using Post-Hoc LSD showed a significant difference between the control group (12.9±2.47 and the chronic immobillization group (9,00±1,53 (p<0.05. In conclusion, the chronic immobillization stress group has the lowest average number of hippocampus CA3 pyramidal cells compared to other groups.

  15. Thermoelectric Properties and Electronic Structure of Ca3Co2O6

    AN Ji-ming; MIN Xin-min; CHEN Sheng-li; NAN Ce-wen


    The nanosized Ca3Co2O6 powder was synthesized via sol-gel process. The phase composition was characterized by means of X-ray diffraction. Polycrystalline samples of Ca3Co2O6 were prepared by a sintering procedure of nanosized power. The seebeck coefficient and electrical conductivity of the samples were measured from 450K up to 750K. The results show that the Seebeck coefficient increases with the increasing temperature. The electronic structures were calculated using the self-consistent full-potential linearized augmented plane-wave(LAPW) method within the density functional theory. The relationship between thermoelectric property and electronic structures was discussed.

  16. Standard model of knowledge representation

    Yin, Wensheng


    Knowledge representation is the core of artificial intelligence research. Knowledge representation methods include predicate logic, semantic network, computer programming language, database, mathematical model, graphics language, natural language, etc. To establish the intrinsic link between various knowledge representation methods, a unified knowledge representation model is necessary. According to ontology, system theory, and control theory, a standard model of knowledge representation that reflects the change of the objective world is proposed. The model is composed of input, processing, and output. This knowledge representation method is not a contradiction to the traditional knowledge representation method. It can express knowledge in terms of multivariate and multidimensional. It can also express process knowledge, and at the same time, it has a strong ability to solve problems. In addition, the standard model of knowledge representation provides a way to solve problems of non-precision and inconsistent knowledge.

  17. Oxygen transport kinetics of the misfit layered oxide Ca3Co4O9+d

    Thoréton, V.; Hu, Y.; Pirovano, C.; Capoen, E.; Nuns, N.; Mamede, A.S.; Dezanneau, G.; Yoo, C.-Y.; Bouwmeester, H.J.M.; Vannier, R.N.


    The oxygen transport kinetics of the misfit-layered cobaltite, Ca3Co4O9+d, known for its thermoelectric properties, was investigated by combined application of 18O/16O isotope exchange and electrical conductivity relaxation techniques. Although oxygen diffusion is found to be two orders of magnitude

  18. Preparation and Luminescence Characteristics of Ca3Y2(BO3)4:Eu3+ Phosphor

    LI Pan-Lai; YANG Zhi-Ping; WANG Zhi-Jun; Guo Qing-Lin


    Ca3Y2(BO3)4:Eu3+ phosphor is synthesized by high temperature solid-state reaction method, and the luminescence characteristics are investigated. The emission spectrum exhibits two strong red emissions at 613 and 621 nm corresponding to the electric dipole 5 Do-7F2 transition of Eu3+ under 365 nm excitation, the reason is that Eu3+ substituting for y3+ occupies the non-centrosymmetric position in the crystal structure of Ca3Y2 (BO3 )4. The excitation spectrum for 613 nm indicates that the phosphor can be effectively excited by ultraviolet (UV) (254 nm,365nm and 400nm) and blue (470nm) light. The effect of Eu3+ concentration on the emission intensity of Ca3Y2 (BO3 )4:Eu3+ phosphor is measured, the result shows that the emission intensities increase with increasing Eu3+ concentration, then decrease. The CIE colour coordinates of Ca3Y2(BO3)4:Eu3+ phosphor is (0.639, 0.357) at 15mol% Eu3+.

  19. Electronic Structure and Thermoelectric Properties of Ca3 Co4O9


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

  20. Insulating state and the importance of the spin-orbit coupling in Ca$_3$CoRhO$_6$

    Wu, Hua; Z. Hu; Khomskii, D. I.; Tjeng, L. H.


    We have carried out a comparative theoretical study of the electronic structure of the novel one-dimensional Ca$_3$CoRhO$_6$ and Ca$_3$FeRhO$_6$ systems. The insulating antiferromagnetic state for the Ca$_3$FeRhO$_6$ can be well explained by band structure calculations with the closed shell high-spin $d^5$ (Fe$^{3+}$) and low-spin $t_{2g}^{6}$ (Rh$^{3+}$) configurations. We found for the Ca$_3$CoRhO$_6$ that the Co has a strong tendency to be $d^7$ (Co$^{2+}$) rather than $d^6$ (Co$^{3+}$), a...

  1. Electronic and Optical Properties of Ca3MN (M = Ge, Sn, Pb, P, As, Sb and Bi) Antiperovskite Compounds

    Iqbal, Samad; Murtaza, G.; Khenata, R.; Mahmood, Asif; Yar, Abdullah; Muzammil, M.; Khan, Matiullah


    The electronic and optical properties of cubic antiperovskites Ca3MN (M = Ge, Sn, Pb, P, As, Sb and Bi) were investigated by applying the full potential linearized augmented plane wave plus local orbitals (FP-LAPW + lo) scheme based on density functional theory. Different exchange correlation potentials were adopted for the calculations. The results of band structure and density of states show that, by changing the central anion of Ca3MN, the nature of the materials change from metallic (Ca3GeN, Ca3SnN, Ca3PbN) to semiconducting with small band gaps (Ca3SbN and Ca3BiN) to insulating (Ca3PN and Ca3AsN). The optical properties such as dielectric function, absorption coefficient, optical conductivity, reflectivity and refractive indices have also been calculated. The results reveal that all the studied compounds are optically active in the visible and ultraviolet energy regions, and therefore can be effectively utilized for optoelectronic devices.

  2. Value Representations

    Rasmussen, Majken Kirkegaard; Petersen, Marianne Graves


    the perspective brings valuable insights on different approaches to technology, but instead to view gender through a value lens. Contributing to this perspective, we have developed Value Representations as a design-oriented instrument for staging a reflective dialogue with users. Value Representations...... are fictional, value-driven concepts developed to promote dialogue with users about their values and how they may materialize with respect to interaction design in their everyday lives....

  3. Terminal Field and Firing Selectivity of Cholecystokinin-Expressing Interneurons in the Hippocampal CA3 Area

    Lasztóczi, Bálint; Tukker, John J; Somogyi, Peter; Klausberger, Thomas


    Hippocampal oscillations reflect coordinated neuronal activity on many timescales. Distinct types of GABAergic interneuron participate in the coordination of pyramidal cells over different oscillatory cycle phases. In the CA3 area, which generates sharp waves and gamma oscillations, the contribution of identified GABAergic neurons remains to be defined. We have examined the firing of a family of cholecystokinin-expressing interneurons during network oscillations in urethane-anesthetized rats ...

  4. Hydrothermal synthesis of Ca3Bi8O15 rods and their visible light photocatalytic properties

    Graphical abstract: The novel Ca3Bi8O15 rods can utilize the sunlight efficiently with the small band-gap. Using methyl orange (MO) as a model organic pollutant, the photocatalysts exhibited good photocatalytic activity, with the photodegradation conversion ratio of MO being up to 90% after 2 h of visible light (420 nm < λ < 800 nm) irradiation. - Highlights: • Ca3Bi8O15 rods were synthesized by a hydrothermal method. • They can utilize the sunlight efficiently with the small band-gap. • They showed good photocatalytic activities in the degradation of MO, RhB and 4-CP. • The conversion ratio of MO was up to 90% after 2 h of visible light irradiation. - Abstract: High efficient visible light Ca3Bi8O15 photocatalysts were synthesized by a hydrothermal method. Characterized by X-ray diffractometer, transmission electron microscopy, and the UV–vis diffuse reflectance spectroscopy, the results showed that the novel Ca3Bi8O15 rods can utilize the sunlight efficiently with the small band-gap. Using methyl orange (MO) as a model organic pollutant, the photocatalysts exhibited good photocatalytic activity, with the photodegradation conversion ratio of MO being up to 90% after 2 h of visible light (420 nm < λ < 800 nm) irradiation. Furthermore, they also showed good photocatalytic activities in the degradation of rhodamine B and p-chlorophenol. Through the investigation of the degraded mechanism, the main active species played important roles in the degradation process were holes, O2·− and ·OH

  5. Optical conductivity of layered calcium cobaltate Ca3Co4O9.

    Tanabe, Kenji; Okazaki, Ryuji; Taniguchi, Hiroki; Terasaki, Ichiro


    We report the optical properties of layered calcium cobaltate, Ca3Co4O9, which is regarded as a promising candidate for use as a thermoelectric material. The optical conductivity shows three broad peaks related to the inter-band transition below 4 eV, which are quite similar to those in the spectra of Na x CoO2. This similarity implies that the CoO2 layer, which is an essential unit for both Ca3Co4O9 and Na x CoO2, is dominant in the energy band structure below 4 eV. In addition, we estimate the effective carrier number per Co site and find similarity between the CoO2 layers of Ca3Co4O9 and Na0.75CoO2, which is consistent with the similarity in their Seebeck coefficients. To discuss the contribution of the rocksalt-type Ca2CoO3 layer in Ca3Co4O9, we propose the concept of optical sheet conductivity in the layered materials and estimate its value in the Ca2CoO3 layer. A comparison with the spin-polarized band calculation of the LDA  +  Hubbard U formalism with U  =  5 eV suggests that the Ca2CoO3 layer has the inter-band transition of 2.6 eV in the spin-down band structure. Evaluation of the valences of Co 3d orbitals indicates the existence of charge transfer from the Ca2CoO3 layer to the CoO2 layer and mixing of Co(3+) and Co(4+) in the CoO2 layer, which may be the origin of the large thermoelectric effect. PMID:26823444

  6. Revising the Subsystem Nurse’s A-Phase-Silicocarnotite within the System Ca3(PO42–Ca2SiO4

    Patricia Ros-Tárraga


    Full Text Available The subsystem Nurse’s A-phase-silicocarnotite within the system Ca3(PO42–Ca2SiO4 was conducted as a preliminary step toward obtaining new biomaterials with controlled microstructures. Phase composition of the resulting ceramics was studied by X-ray diffraction, differential thermal analysis, and scanning electron microscopy with attached wavelength dispersive spectroscopy. The results showed that the sub-system presents an invariant eutectoid point at 1366 ± 4 °C with a composition of 59.5 wt % Ca3(PO42 and 40.5 wt % Ca2SiO4, and typical eutectoid microstructure of lamellae morphology. These results are in disagreement with the previous reported data, which locate the invariant eutectoid point at 1250 ± 20 °C with a composition of 55 wt % Ca3(PO42 and 45 wt % Ca2SiO4. In addition, cell attachment testing showed that the new eutectoid material supported the mesenchymal stem cell adhesion and spreading, and the cells established close contact with the ceramic after 28 days of culture. These findings indicate that the new ceramic material with eutectoid microstructure of lamellae morphology possesses good bioactivity and biocompatibility and might be a promising bone implant material.

  7. Crystal structure of Ca 3(VO 4) 2 synthesized at 11 GPa and 1373 K

    Grzechnik, Andrzej


    A new polymorph of calcium orthovanadate Ca 3(VO 4) 2 has been synthesized at 11 GPa and 1373 K and recovered to ambient conditions. It crystallizes in a monoclinic cell (space group C2/m, Z=2) with a=9.6715(2), b=5.43276(7), c=7.0713(1) Å, β=116.949(1)°. The crystal structure has been solved ab initio from X-ray powder diffraction data using direct methods. The oxygen atoms form a hexagonal close packing. The VO 3-4 tetrahedra are radially and angularly distorted. The two crystallographically independent Ca atoms are in deformed octahedral and ten-fold coordinations. Unlike in the palmierite-derived parent Ba 3(VO 4) 2 (R 3¯m, Z=1) and Ca 3(VO 4) 2 (R3c, Z=7), this network is three-dimensional. The new monoclinic structure of calcium orthovanadate is discussed in relation to those of related orthophosphates and orthovanadates. It is suggested that the pressure-induced amorphization of Ca 3(VO 4) 2 (R3c, Z=7) at 10 GPa and room temperature could be due to kinetically inhibited changes in the dimensionality of the crystal structure.

  8. Optical-luminescence properties of Ce3+ ions in Ca3 Ga2 Ge4O14 single crystals

    The optical-luminescence spectroscopic properties of Ca3 Ga2 Ge4 O14 single crystals doped with Ce3+ ions are investigated. It is shown that activator ions in Ca3 Ga2 Ge4 O14 form Ce3+ centers in Thomson cubes (3 e positions)

  9. Group representations

    Karpilovsky, G


    This third volume can be roughly divided into two parts. The first part is devoted to the investigation of various properties of projective characters. Special attention is drawn to spin representations and their character tables and to various correspondences for projective characters. Among other topics, projective Schur index and projective representations of abelian groups are covered. The last topic is investigated by introducing a symplectic geometry on finite abelian groups. The second part is devoted to Clifford theory for graded algebras and its application to the corresponding theory

  10. Representation is representation of similarities.

    Edelman, S


    Advanced perceptual systems are faced with the problem of securing a principled (ideally, veridical) relationship between the world and its internal representation. I propose a unified approach to visual representation, addressing the need for superordinate and basic-level categorization and for the identification of specific instances of familiar categories. According to the proposed theory, a shape is represented internally by the responses of a small number of tuned modules, each broadly selective for some reference shape, whose similarity to the stimulus it measures. This amounts to embedding the stimulus in a low-dimensional proximal shape space spanned by the outputs of the active modules. This shape space supports representations of distal shape similarities that are veridical as Shepard's (1968) second-order isomorphisms (i.e., correspondence between distal and proximal similarities among shapes, rather than between distal shapes and their proximal representations). Representation in terms of similarities to reference shapes supports processing (e.g., discrimination) of shapes that are radically different from the reference ones, without the need for the computationally problematic decomposition into parts required by other theories. Furthermore, a general expression for similarity between two stimuli, based on comparisons to reference shapes, can be used to derive models of perceived similarity ranging from continuous, symmetric, and hierarchical ones, as in multidimensional scaling (Shepard 1980), to discrete and nonhierarchical ones, as in the general contrast models (Shepard & Arabie 1979; Tversky 1977). PMID:10097019

  11. Energy transfer and luminescence dynamics in Ca3Gd2(BO3)4:Eu3+

    Eu3+-doped and -undoped Ca3Gd2(BO3)4 phosphors were synthesized by the high temperature solid-state reaction. The excitation and emission spectra and the decays of the Gd3+ and Eu3+ luminescence in Ca3Gd2(BO3)4:Eu3+ under excitation into the self-trapped excitation (STE) state are investigated in the wavelength region from vacuum ultraviolet to visible. The efficient energy transfer occurs from the host STE state to the emitting state of Eu3+5D0 via two intermediate states: the Gd3+6P7/2 state or the O–Eu charge transfer state. The analyses of decay curves of the Eu3+5D0 emission at 615 nm and the Gd3+6P7/2 emission at 314 nm show much faster energy transfer from Gd3+ to Eu3+ than the energy diffusion among the Gd3+ ions. -- Highlights: • Luminescence dynamics are investigated in Ca3Gd2(BO3)4:Eu3+. • The excited STE state relaxes to the Eu3+5D0 state through the Gd3+6P7/2 state or the O–Eu charge transfer state. • Much faster energy transfer occurs from Gd to Eu than the energy diffusion among the Gd3+ ions. • The feeding of the 5D0 population occurs dominantly from the O–Eu charge transfer state at higher Eu3+ concentration

  12. High-pressure crystal growth and electromagnetic properties of 5d double-perovskite Ca3OsO6

    Single crystals of the osmium-containing compound Ca3OsO6 have been successfully grown under high-pressure conditions, for the first time. The crystal structure of Ca3OsO6 were characterized as an ordered double-perovskite structure of space group P21/n with the Ca and Os atoms being fully ordered at the perovskite B-site. The electromagnetic analysis shows that the crystal exhibits a semiconductor-like behavior below 300 K and undergoes an antiferromagnetic transition at 50 K. - Graphical Abstract: Schematic image of crystal structure of Ca3OsO6 as determined by X-ray diffraction, where the gray and black octahedrons are occupied by Ca and Os, respectively. Top inset reveals an optic image of a typical Ca3OsO6 single crystal. Highlights: ► Single crystals of Ca3OsO6 have been successfully grown under high-pressure. ► Ca3OsO6 crystalizes into an ordered double-perovskite structure. ► The Ca3OsO6 undergoes an antiferromagnetic transition at 50 K

  13. Regulation of phenylacetic acid uptake is σ54 dependent in Pseudomonas putida CA-3

    O' Mahony Mark M


    Full Text Available Abstract Background Styrene is a toxic and potentially carcinogenic alkenylbenzene used extensively in the polymer processing industry. Significant quantities of contaminated liquid waste are generated annually as a consequence. However, styrene is not a true xenobiotic and microbial pathways for its aerobic assimilation, via an intermediate, phenylacetic acid, have been identified in a diverse range of environmental isolates. The potential for microbial bioremediation of styrene waste has received considerable research attention over the last number of years. As a result the structure, organisation and encoded function of the genes responsible for styrene and phenylacetic acid sensing, uptake and catabolism have been elucidated. However, a limited understanding persists in relation to host specific regulatory molecules which may impart additional control over these pathways. In this study the styrene degrader Pseudomonas putida CA-3 was subjected to random mini-Tn5 mutagenesis and mutants screened for altered styrene/phenylacetic acid utilisation profiles potentially linked to non-catabolon encoded regulatory influences. Results One mutant, D7, capable of growth on styrene, but not on phenylacetic acid, harboured a Tn5 insertion in the rpoN gene encoding σ54. Complementation of the D7 mutant with the wild type rpoN gene restored the ability of this strain to utilise phenylacetic acid as a sole carbon source. Subsequent RT-PCR analyses revealed that a phenylacetate permease, PaaL, was expressed in wild type P. putida CA-3 cells utilising styrene or phenylacetic acid, but could not be detected in the disrupted D7 mutant. Expression of plasmid borne paaL in mutant D7 was found to fully restore the phenylacetic acid utilisation capacity of the strain to wild type levels. Bioinformatic analysis of the paaL promoter from P. putida CA-3 revealed two σ54 consensus binding sites in a non-archetypal configuration, with the transcriptional start site

  14. The antiferromagnetic insulator Ca3FeRhO6: characterization and electronic structure calculations

    Eyert, V.; Schwingenschloegl, U.; Fresard, R.; Maignan, A.; Martin, C.; Nguyen, N.; Hackenberger, C.; Kopp, T.


    We investigate the antiferromagnetic insulating nature of Ca3FeRhO6 both experimentally and theoretically. Susceptibility measurements reveal a Neel temperature T_N = 20 K, and a magnetic moment of 5.3 muB/f. u., while Moessbauer spectroscopy strongly suggests that the Fe ions, located in trigonal prismatic sites, are in a 3+ high spin state. Transport measurements display a simple Arrhenius law, with an activation energy of 0.2 eV. The experimental results are interpreted with LSDA band stru...

  15. Oxygen consumption rates during three different neuronal activity states in the hippocampal CA3 network

    Huchzermeyer, Christine; Berndt, Nikolaus; Holzhütter, Hermann-Georg; Kann, Oliver


    The brain is an organ with high metabolic rate. However, little is known about energy utilization during different activity states of neuronal networks. We addressed this issue in area CA3 of hippocampal slice cultures under well-defined recording conditions using a 20% O2 gas mixture. We combined recordings of local field potential and interstitial partial oxygen pressure (pO2) during three different activity states, namely fast network oscillations in the gamma-frequency band (30 to 100 Hz)...

  16. High-temperature stability of thermoelectric Ca3Co4O9 thin films

    Brinks, P.; Van Nong, Ngo; Pryds, Nini;


    An enhanced thermal stability in thermoelectric Ca3Co4O9 thin films up to 550 °C in an oxygen rich environment was demonstrated by high-temperature electrical and X-ray diffraction measurements. In contrast to generally performed heating in helium gas, it is shown that an oxygen/helium mixture...... provides sufficient thermal contact, while preventing the previously disregarded formation of oxygen vacancies. Combining thermal cycling with electrical measurements proves to be a powerful tool to study the real intrinsic thermoelectric behaviour of oxide thin films at elevated temperatures. © 2015 AIP...

  17. Regulation of phenylacetic acid uptake is sigma54 dependent in Pseudomonas putida CA-3.

    O' Leary, Niall D


    Abstract Background Styrene is a toxic and potentially carcinogenic alkenylbenzene used extensively in the polymer processing industry. Significant quantities of contaminated liquid waste are generated annually as a consequence. However, styrene is not a true xenobiotic and microbial pathways for its aerobic assimilation, via an intermediate, phenylacetic acid, have been identified in a diverse range of environmental isolates. The potential for microbial bioremediation of styrene waste has received considerable research attention over the last number of years. As a result the structure, organisation and encoded function of the genes responsible for styrene and phenylacetic acid sensing, uptake and catabolism have been elucidated. However, a limited understanding persists in relation to host specific regulatory molecules which may impart additional control over these pathways. In this study the styrene degrader Pseudomonas putida CA-3 was subjected to random mini-Tn5 mutagenesis and mutants screened for altered styrene\\/phenylacetic acid utilisation profiles potentially linked to non-catabolon encoded regulatory influences. Results One mutant, D7, capable of growth on styrene, but not on phenylacetic acid, harboured a Tn5 insertion in the rpoN gene encoding σ54. Complementation of the D7 mutant with the wild type rpoN gene restored the ability of this strain to utilise phenylacetic acid as a sole carbon source. Subsequent RT-PCR analyses revealed that a phenylacetate permease, PaaL, was expressed in wild type P. putida CA-3 cells utilising styrene or phenylacetic acid, but could not be detected in the disrupted D7 mutant. Expression of plasmid borne paaL in mutant D7 was found to fully restore the phenylacetic acid utilisation capacity of the strain to wild type levels. Bioinformatic analysis of the paaL promoter from P. putida CA-3 revealed two σ54 consensus binding sites in a non-archetypal configuration, with the transcriptional start site being resolved by

  18. Pycnogenol protects CA3-CA1 synaptic function in a rat model of traumatic brain injury.

    Norris, Christopher M; Sompol, Pradoldej; Roberts, Kelly N; Ansari, Mubeen; Scheff, Stephen W


    Pycnogenol (PYC) is a patented mix of bioflavonoids with potent anti-oxidant and anti-inflammatory properties. Previously, we showed that PYC administration to rats within hours after a controlled cortical impact (CCI) injury significantly protects against the loss of several synaptic proteins in the hippocampus. Here, we investigated the effects of PYC on CA3-CA1 synaptic function following CCI. Adult Sprague-Dawley rats received an ipsilateral CCI injury followed 15 min later by intravenous injection of saline vehicle or PYC (10 mg/kg). Hippocampal slices from the injured (ipsilateral) and uninjured (contralateral) hemispheres were prepared at seven and fourteen days post-CCI for electrophysiological analyses of CA3-CA1 synaptic function and induction of long-term depression (LTD). Basal synaptic strength was impaired in slices from the ipsilateral, relative to the contralateral, hemisphere at seven days post-CCI and susceptibility to LTD was enhanced in the ipsilateral hemisphere at both post-injury timepoints. No interhemispheric differences in basal synaptic strength or LTD induction were observed in rats treated with PYC. The results show that PYC preserves synaptic function after CCI and provides further rationale for investigating the use of PYC as a therapeutic in humans suffering from neurotrauma. PMID:26607913

  19. Thermoelectric transport in the layered Ca3Co4-xRhxO9 single crystals

    Ikeda, Yusuke; Saito, Kengo; Okazaki, Ryuji


    We have examined an isovalent Rh substitution effect on the transport properties of the thermoelectric oxide Ca3Co4O9 using single-crystalline form. With increasing Rh content x, both the electrical resistivity and the Seebeck coefficient change systematically up to x = 0.6 for Ca3Co4-xRhxO9 samples. In the Fermi-liquid regime where the resistivity behaves as ρ = ρ 0 + A T 2 around 120 K, the A value decreases with increasing Rh content, indicating that the correlation effect is weakened by Rh 4d electrons with extended orbitals. We find that, in contrast to such a weak correlation effect observed in the resistivity of Rh-substituted samples, the low-temperature Seebeck coefficient is increased with increasing Rh content, which is explained with a possible enhancement of a pseudogap associated with the short-range order of spin density wave. In high-temperature range above room temperature, we show that the resistivity is largely suppressed by Rh substitution while the Seebeck coefficient becomes almost temperature-independent, leading to a significant improvement of the power factor in Rh-substituted samples. This result is also discussed in terms of the differences in the orbital size and the associated spin state between Co 3d and Rh 4d electrons.

  20. Dopamine D3 receptors inhibit hippocampal gamma oscillations by disturbing CA3 pyramidal cell firing synchrony

    Clément E. Lemercier


    Full Text Available Cortical gamma oscillations are associated with cognitive processes and are altered in several neuropsychiatric conditions such as schizophrenia and Alzheimer’s disease. Since dopamine D3 receptors are possible targets in treatment of these conditions, it is of great importance to understand their role in modulation of gamma oscillations. The effect of D3 receptors on gamma oscillations and the underlying cellular mechanisms were investigated by extracellular local field potential and simultaneous intracellular sharp micro-electrode recordings in the CA3 region of the hippocampus in vitro. D3 receptors decreased the power and broadened the bandwidth of gamma oscillations induced by acetylcholine or kainate. Blockade of the D3 receptors resulted in faster synchronization of the oscillations, suggesting that endogenous dopamine in the hippocampus slows down the dynamics of gamma oscillations by activation of D3 receptors. Investigating the underlying cellular mechanisms for these effects showed that D3 receptor activation decreased the rate of action potentials during gamma oscillations and reduced the precision of the action potential phase coupling to the gamma cycle in CA3 pyramidal cells. The results may offer an explanation how selective activation of D3 receptors may impair cognition and how, in converse, D3 antagonists may exert pro-cognitive and antipsychotic effects.

  1. Dopamine D3 Receptors Inhibit Hippocampal Gamma Oscillations by Disturbing CA3 Pyramidal Cell Firing Synchrony.

    Lemercier, Clément E; Schulz, Steffen B; Heidmann, Karin E; Kovács, Richard; Gerevich, Zoltan


    Cortical gamma oscillations are associated with cognitive processes and are altered in several neuropsychiatric conditions such as schizophrenia and Alzheimer's disease. Since dopamine D3 receptors are possible targets in treatment of these conditions, it is of great importance to understand their role in modulation of gamma oscillations. The effect of D3 receptors on gamma oscillations and the underlying cellular mechanisms were investigated by extracellular local field potential and simultaneous intracellular sharp micro-electrode recordings in the CA3 region of the hippocampus in vitro. D3 receptors decreased the power and broadened the bandwidth of gamma oscillations induced by acetylcholine or kainate. Blockade of the D3 receptors resulted in faster synchronization of the oscillations, suggesting that endogenous dopamine in the hippocampus slows down the dynamics of gamma oscillations by activation of D3 receptors. Investigating the underlying cellular mechanisms for these effects showed that D3 receptor activation decreased the rate of action potentials (APs) during gamma oscillations and reduced the precision of the AP phase coupling to the gamma cycle in CA3 pyramidal cells. The results may offer an explanation how selective activation of D3 receptors may impair cognition and how, in converse, D3 antagonists may exert pro-cognitive and antipsychotic effects. PMID:26779018

  2. Shubnikov-de Haas oscillations in Ca3Ru2O7 under pressure

    The bilayer ruthenate Ca3Ru2O7 undergoes a series of phase transitions on cooling, which lead to a low carrier density state at low temperature. Hydrostatic pressure is applied on this material in order to track the Fermi surface whilst tuning and ultimately suppressing the high temperature phase transitions. Quantum oscillations in the Hall component of Ca3Ru2O7 are investigated as a function pressure using a piston-cylinder cell. As the pressure is increased, the oscillation frequency decreases systematically, suggesting that the Fermi pockets shrink. Owing to the size of the frequencies and to the non-linear background, the evolution of the effective masses cannot be determined accurately enough to extract a trend other than that they remain of the order of 0.6me. Further work at higher pressures is under way, using anvil cells, to track the evolution of the Fermi surface through the pressures where the magnetic and structural transitions eventually are suppressed.

  3. Poetic representation

    Wulf-Andersen, Trine Østergaard


    This article is based on a Danish research project with young people in vulnerable positions. Young people are involved throughout the research process, including the interpretation of material produced through interviews, and discussions on how reflections and conclusions from the research should...... be written up and disseminated. The article takes a methodological focus, considering general aims and methods of the research project, before turning to the elaboration on how poetic representations have been constructed and employed as a vehicle for certain kinds of participation, representation...... participative social work research. The article moves to ‘trouble’ understandings of participative research as egalitarian and consensus-driven, and proposes a focus on the tensions and positioning of knowledge production....

  4. Disappearance of Ising nature in Ca3ZnMnO6 studied by high-field ESR

    High-field electron spin resonance measurements of an antiferromagnet Ca3ZnMnO6 isostructure, with the Ising-chain multiferroic Ca3CoMnO6, have been carried out. Two distinct resonance modes were observed below TN = 25 K, which is well explained by conventional antiferromagnetic resonance theory with easy-plane anisotropy. The zero-field spin gap is derived to be about 166 GHz, originating from the easy-plane anisotropy and exchange interaction. Our result suggests that the Dzyaloshinsky–Moriya interaction, which may induce spin canting, is absent. Disappearance of Ising anisotropy in Ca3ZnMnO6 suggests that the Co4+ ion, as well as the Co–Mn superexchange, plays an important role for the Ising nature in Ca3CoMnO6. (paper)

  5. Cationic disorder and Mn3+/Mn4+ charge ordering in the B′ and B″ sites of Ca3Mn2NbO9 perovskite: a comparison with Ca3Mn2WO9

    We describe the preparation, crystal structure determination, magnetic and transport properties of two novel Mn-containing perovskites, with a different electronic configuration for Mn atoms located in B site. Ca3Mn3+2WO9 and Ca3Mn3+/4+2NbO9 were synthesized by standard ceramic procedures; the crystallographic structure was studied from X-ray powder diffraction (XRPD) and neutron powder diffraction (NPD). Both phases exhibit a monoclinic symmetry (S.G.: P21/n); Ca3Mn2WO9 presents a long-range ordering over the B sites, whereas Ca3Mn2NbO9 is strongly disordered. By “in-situ” NPD, the temperature evolution of the structure study presents an interesting evolution in the octahedral size (〈Mn–O〉) for Ca3Mn2NbO9, driven by a charge ordering effect between Mn3+ and Mn4+ atoms, related to the anomaly observed in the transport measurements at T≈160 K. Both materials present a magnetic order below TC=30 K and 40 K for W and Nb materials, respectively. The magneto-transport measurements display non-negligible magnetoresistance properties in the paramagnetic regime. - Graphical abstract: Comparison between the octahedron size and the magnetic behaviour for Ca3Mn2NbO9 in the temperature region where the charge and magnetic order occur. Display Omitted - Highlights: • Two novel Mn-containing double perovskites were obtained by solid-state reactions. • Both double perovskites are monoclinic (P21/n) determined by XRPD and NPD. • Ca3Mn2WO9 contains Mn3+ while Ca3Mn2NbO9 includes mixed-valence cations Mn3+/Mn4+. • Ca3Mn2NbO9 presents a charge-ordering effect between Mn3+ and Mn4+ evidenced by NPD. • The magnetic and transport studies evidenced the charge ordering in Ca3Mn2NbO9

  6. Synthesis, structure and Eu2+-doped luminescence properties of bromosilicate compound Ca3SiO4Br2

    The bromosilicate Ca3SiO4Br2 crystal has been grown, and this compound crystallizes in triclinic symmetry, space group P-1 (No. 2), with unit cell parameters: a=8.0051(18) Å, b=8.720(3) Å, c=11.749(3)Å, α=69.07(0)°, β=89.98(0)°, γ=75.46(0)°, and cell volume V=737.88(1 9 6)Å3, Z=3. The unit cell of the Ca3SiO4Br2 crystal is composed of the alternating layers of CaBr2 and Ca2SiO4, therefore, the luminescence of Ca3SiO4Br2:Eu2+ gives a broad emission band centered at 469 nm with some asymmetry on the long wavelength side with different coordination environment. Their detailed photoluminescence (PL) properties, PL decay curves and the temperature dependent PL behavior were also discussed. - Highlights: ► The Ca3SiO4Br2 crystal has been grown and the structure has been analyzed. ► Ca3SiO4Br2:Eu2+ gives a blue emission band centered at 469 nm. ► PL decay curves and the temperature dependent PL behavior of Ca3SiO4Br2:Eu2+ have been discussed.

  7. A structural change in Ca3Co4O9 associated with enhanced thermoelectric properties

    Temperature dependent electrical resistivity, crystal structure and heat capacity measurements reveal a resistivity drop and electrical transport behavior change corresponding to a structural change near 400 K in Ca3Co4O9. The lattice parameter c varies smoothly with increasing temperature while anomalies in a, b1 and b2 lattice parameters occur near 400 K. The Ca site in the Ca2CoO3 block becomes distorted and a change in electrical transport behavior is found above 400 K. Resistivity and heat capacity measurements as a function of temperature under magnetic field combined with Co L-edge x-ray absorption spectra reveal only a weak spin contribution to this change. Reduced resistivity associated with the structural change enhances the thermoelectric properties at moderately high temperatures and points to the electrical transport behavior change as a mechanism for improved ZT in this thermoelectric oxide.

  8. Scintillation characteristics of Tm3+ in Ca3(BO3)2 crystals

    Basic optical properties and radiation responses of undoped, Tm3+ 1.0% and 2.0% activated Ca3(BO3)2 (CBO) crystalline scintillator prepared by the micro-pulling down (μ-PD) method are reported. Tm3+: CBO crystals showed three weak absorption bands around 190, 260 and 350 nm, owing to the Tm3+ 4f–4f transition. Strong blue luminescence peaks at 360 and 460 nm which are ascribed to the 1D2–3H6 and 1D2–3F4 transitions of Tm3+ respectively were observed under 241Am 5.5 MeV α-ray excitation. The scintillation light yield of 2.0% Tm3+-doped CBO crystal was evaluated to be about 250 ph/n from the 252Cf excited pulse height spectrum.

  9. Anisotropic laser properties of Yb:Ca3La2(BO3)4 disordered crystal

    Wang, Lisha; Xu, Honghao; Pan, Zhongben; Han, Wenjuan; Chen, Xiaowen; Liu, Junhai; Yu, Haohai; Zhang, Huaijin


    A study is carried out experimentally on the anisotropy in the laser action of Yb:Ca3La2(BO3)4 disordered crystal, demonstrated with the output coupling changed over a wide range from 0.5% to 40%. Complex polarization state variation with output coupling and evolution with pump power are observed in the laser operation achieved with a- and c-cut crystal samples. A maximum output power of 8.2 W is produced at wavelengths around 1043 nm, with an incident pump power of 24.9 W, the optical-to-optical efficiency being 33%. The polarized absorption and emission cross section spectra are also presented.

  10. Manipulating Representations.

    Recchia-Luciani, Angelo N M


    The present paper proposes a definition for the complex polysemic concepts of consciousness and awareness (in humans as well as in other species), and puts forward the idea of a progressive ontological development of consciousness from a state of 'childhood' awareness, in order to explain that humans are not only able to manipulate objects, but also their mental representations. The paper builds on the idea of qualia intended as entities posing regular invariant requests to neural processes, trough the permanence of different properties. The concept of semantic differential introduces the properties of metaphorical qualia as an exclusively human ability. Furthermore this paper proposes a classification of qualia, according to the models-with different levels of abstraction-they are implied in, in a taxonomic perspective. This, in turn, becomes a source of categorization of divergent representations, sign systems, and forms of intentionality, relying always on biological criteria. New emerging image-of-the-world-devices are proposed, whose qualia are likely to be only accessible to humans: emotional qualia, where emotion accounts for the invariant and dominant property; and the qualic self where continuity, combined with the oneness of the self, accounts for the invariant and dominant property. The concept of congruence between different domains in a metaphor introduces the possibility of a general evaluation of truth and falsity of all kinds of metaphorical constructs, while the work of Matte Blanco enables us to classify conscious versus unconscious metaphors, both in individuals and in social organizations. PMID:22347988

  11. Effects of movement training on synaptic interface structure in the sensorimotor cortex and hippocampal CA3 area of the ischemic hemisphere in cerebral infarction rats

    Min Yang; Jiyan Cheng


    BACKGROUND: Movement is an effective way to provide sensory, movement and reflectivity afferent stimulation to the central nervous system. Movement plays an important role in functional recombination and compensation in the brain. OBJECTIVE: To observe movement training effects on texture parameters of synaptic interfaces in the sensorimotor cortex and hippocampal CA3 area of the ischemic hemisphere and on motor function in cerebral infarction rats. DESIGN, TIME AND SETTING: This neural morphology and pathology randomized controlled animal experiment was performed at the Center Laboratory, Affiliated Hospital of Luzhou Medical College, China from November 2004 to April 2005. MATERIALS: A total of 32 healthy male Wistar rats aged 8 weeks were equally and randomly assigned into model and movement training groups. METHODS: Rat models of right middle cerebral artery occlusion were established using the suture occlusion method in both groups. Rats in the movement training group underwent balance training, screen training, and rotating rod training starting on day 5 after surgery, for 40 minutes every day, 6 days per week, for 4 weeks. MAIN OUTCOME MEASURES: Texture parameters of synaptic interfaces were determined using a transmission electron microscope and image analyzer during week 5 following model induction. The following parameters were measured: synaptic cleft width; postsynaptic density thickness; synaptic interface curvature; and active zone length. Motor function was assessed using balance training, screen training, and rotating rod training. The lower score indicated a better motor function. RESULTS: The postsynaptic density thickness, synaptic interface curvature, and active zone length were significantly increased in the sensorimotor cortex and hippocampal CA3 area of the ischemic hemisphere of rats from the movement training group compared with the model group (P < 0.05 or 0.01). Curved synapses and perforated synapses were seen in the sensorimotor cortex

  12. Negative chemical pressure effects induced by Y substitution for Ca on the `exotic' magnetic behavior of the spin-chain compound, Ca3Co2O6

    S Rayaprol; E V Sampathkumaran


    The magnetic behavior of a solid solution, Ca3-YCo2O6, based on the `exotic' spin-chain compound, Ca3Co2O6, crystallizing in K4CdCl6-derived rhombohedral structure is investigated. Among the compositions investigated ( = 0.0, 0.3, 0.5, 0.75 and 1.0), single-phase formation persists up to = 0.75, with the elongation of the -axis. The present investigations reveal that the temperature at which the `so-called' `partially disordered antiferromagnetic structure' sets in (which occurs at 24 K for the parent compound, = 0.0) undergoes gradual reduction with the substitution of Y for Ca, attaining the value of about 2.2 K for the nominal = 1.0. The trend observed in this characteristic temperature is opposite to that reported under external pressure, thereby establishing that Y substitution exerts negative chemical pressure. Anomalous steps observed in the isothermal magnetization at very low temperatures (around 2 K) for = 0.0, which have been proposed to arise from `quantum tunneling effects' are found to vanish by a small substitution ( = 0.3) of Y for Ca. Systematics in AC and DC magnetic susceptibility behavior with Y substitution for Ca have also been probed. We believe that the present results involving the expansion of chain length without disrupting the magnetic chain may be useful to the overall understanding of the novel magnetism of the parent compound.

  13. (Cu,Tl)Ba2Ca3Cu4Ox compositions: II. Heating rate applied to synthesis of superconducting ceramics

    Superconducting samples with a starting composition Cu0.5TlxBa2Ca3Cu4O12 (x=1-0.35) were prepared in Au tubes from oxides by using different heating rates. The optimum heating rate was 0.11 deg. C min-1 applied between 860 and 880 deg. C. These samples show the highest content of 1234 phase and the lowest of Ba-Cu-O phases as well as the highest critical temperatures. The highest values were Tc=119.2 K and Tc0=115.1 K. All samples show Jc values around 6x105 A cm-2, at 60 K and 0.5 T. In the rest of the samples, heated by using lower or higher heating rates, a high concentration of 1223 and/or 1245 phases is detected. The content of the 1234 phase and of Ba(Ca,Tl)-Cu-O residual liquid phase, in the samples synthesized for the optimum heating rate, depends on the Tl content in the starting mixture. The influence of the oxygen content in the starting mixture on phase composition is not as strong as of Tl, but it has a major role in establishing the superconducting behaviour of the 1234 grains. Some arguments that suggest the dependence of the transport properties of the non-superconducting matrix on oxygen content will be discussed. In our technological arrangement the determined optimum heating rate can be applied to the synthesis of other single-layered superconducting phases, e.g. 1212 phase from a Cu0.25Tl0.75Ba2CaCu2O8.115 starting composition. (author)

  14. Representational Thickness

    Mullins, Michael

    be implemented to improve design conditions for architects, thereby increasing the “thickness of representation”. The study commences from a broader theoretical enquiry, a review of previous research and examples of relevant context in which virtual reality has been used in practice. It develops from......Contemporary communicational and informational processes contribute to the shaping of our physical environment by having a powerful influence on the process of design. Applications of virtual reality (VR) are transforming the way architecture is conceived and produced by introducing dynamic...... elements into the process of design. Through its immersive properties, virtual reality allows access to a spatial experience of a computer model very different to both screen based simulations as well as traditional forms of architectural representation. The dissertation focuses on processes of the current...

  15. Epitaxial growth of one-dimensional Ca3Co2O6 thin films prepared by pulsed laser deposition

    Moubah, R.; Bouaine, A.; Ulhaq-Bouillet, C.; Schmerber, G.; Versini, G.; Barre, S.; Loison, J. L.; Drillon, M.; Colis, S.; Dinia, A.


    We report on the growth and structural properties of Ca3Co2O6 thin films deposited by pulsed laser ablation on SrTiO3 substrates heated at 700°C. In situ reflection high-energy electron diffraction and ex situ atomic force microscopy observations reveal that Ca3Co2O6 grows in a three-dimensional (3D) mode with a surface roughness of about 1.5nm rms. X-ray diffraction and cross-section transmission electron microscopy characterizations show that the deposited films are epitaxial without secondary phases and with a preferential growth orientation perpendicular to the (220) plane. Temperature dependent magnetization measurements reveal that the ferrimagnetic-ferromagnetic transition in the Ca3Co2O6 film is shifted toward higher temperatures with respect to the bulk cobaltite.

  16. Thermoelectric properties of Al substituted misfit cobaltite Ca3(Co1-xAlx)4O9 at low temperature

    Yi Liu; Hong-mei Chen; Jin-lian Hu; Xu-bing Tang; Hai-jin Li; Wei Wang


    Thermoelectric properties of Al substituted compounds Ca3(Co1−xAlx)4O9 (x=0, 0.03, 0.05), prepared by a sol−gel process, have been investigated in the temperature range 305−20 K. The results indicate that after Al substitution for Co in Ca3(Co1−xAlx)4O9, the direct current electrical resistivity and thermopower increase due to the reduction of carrier concentration. Experiments show that Al substitution results in decreased lattice thermal conductivity. The figure of merit of temperature behavior suggests that Ca3(Co0.97Al0.03)4O9 would be a promising candidate thermoelectric material for high-temperature thermoelectric application.

  17. Enhancing the thermoelectric properties of Ca3Co4O9 thin films by Nb ion injection

    Highlights: •High quality Ca3Co4O9 thin films have been epitaxially grown on single crystal Al2O3 substrate. •Nb element was implanted into Ca3Co4O9 thin film by ion beam injection technique. •The effect of Nb doping was verified by resistivity measurement at room temperature. •Resistivity and Seebeck coefficient were measured in the temperature range 150–380 K. •The power factors of Ca3Co4O9 thin films increase when Nb doped. -- Abstract: High quality Ca3Co4O9 thin films have been grown epitaxially on single crystal Al2O3 substrates with pulsed laser deposition. Nb was implanted into the Ca3Co4O9 films using an ion beam injection technique. The microstructure of the thin films has been investigated by XRD, SEM and AFM. The epitaxial thin films were grown with the c-axis perpendicular to the substrate surface. The effect of Nb doping by ion beam injection was verified using resistivity measurements at room temperature. Resistivity and the Seebeck coefficient were also measured in the temperature range 150–380 K. The results indicate that the power factors of Ca3Co4O9 thin films increase when doped with Nb. When the concentration of doped Nb was 3.65 × 1019 atoms/cm3, the power factor of the thin films reached 0.10 mW/m K2 at room temperature, and it approached a maximum of 0.17 mW/m K2 at 380 K

  18. Metamagnetism of single crystal Ca3Ru2O7 in high magnetic fields

    Ca3Ru2O7, which has a double-layered structure related to perovskites and high-Tc cuprates, exhibits several coupled magnetic and transport phases. As-grown single crystals have nonmetallic conductivity for T M=48K, antiferromagnetic ordering up to TN=56 K and bad metal conductivity, linear in temperature for T > TN. The current study reveals a metamagnetic transition with an accompanying nonmetal to metal transition found in pulsed high magnetic fields (Hc=37 T) for the field directed perpendicular to the Ru-O planes in the 'hard' axis (0 0 1) direction of this highly anisotropic system. By contrast, the transition occurs at 6T for the field along the 'easy' axis (1 1 0). The resistivity for current along (1 1 0) or (0 0 1) is anisotropic in zero field at low temperatures but becomes isotropic with H > Hc applied along the easy axis, in contrast to results expected from Fermi-liquid models

  19. Effects of Synthesis and Spark Plasma Sintering Conditions on the Thermoelectric Properties of Ca3Co4O9+δ

    Wu, NingYu; Holgate, Tim; Van Nong, Ngo;


    Ca3Co4O9+δ samples were synthesized by solid-state (SS) and sol–gel (SG) reactions, followed by spark plasma sintering under different processing conditions. The synthesis process was optimized and the resulting materials characterized with respect to their microstructure, bulk density, and therm......Ca3Co4O9+δ samples were synthesized by solid-state (SS) and sol–gel (SG) reactions, followed by spark plasma sintering under different processing conditions. The synthesis process was optimized and the resulting materials characterized with respect to their microstructure, bulk density...

  20. Crystal Growth and Characterization of Ca3NbGa3Si2O14 Single Crystal


    Single crystals of Ca3NbGa3Si2O14 (CNGS) with ordered Ca3Ga2Ge4O14 (CGG) structure were successfully grown from stoichiometric melts by conventional Czochralski technique along the a-axis and two large (001) facets and two small (100) facets appear in every crystal. An arrangement of parallel steps and a clear height change were observed in (001) facet by atomic force microscopy (AFM). High-resolution X-ray diffraction (HRXRD) results indicate that CNGS crystals have good quality and free low-angle boundaries. The crystals also exhibit good optical quality and high optical transmittance in c-direction.

  1. First principles study of the electronic structure and magnetic properties of spin chain compounds: Ca3ZnMnO6 and Ca3ZnCoO6.

    Chakraborty, Jayita; Samanta, Subhasis; Nanda, B R K; Dasgupta, I


    We have studied the electronic structure and magnetism of the spin chain compounds Ca3ZnMnO6 and Ca3ZnCoO6 using density functional theory with generalised gradient approximation (GGA). In agreement with experiment our calculations reveal that high spin (HS) state for Mn(4+) ion and low spin (LS) state for Co(4+) ion stabilize the magnetic structure of the respective compounds. The magnetic exchange paths, calculated using Nth order muffin-tin orbital downfolding method, shows dominant intra-chain exchange interaction between the magnetic ions (Mn, Co) is antiferromagnetic for Ca3ZnMnO6 and ferromagnetic for Ca3ZnCoO6. The magnetic order of both the compounds is in accordance with the Goodenough-Kanamori-Anderson rules and is consistent with the experimental results. Finally we have investigated the importance of spin-orbit coupling (SOC) in these compounds. While SOC practically has no effect for the Mn system, it is strong enough to favor the spin quantization along the chain direction for the Co system in the LS state. PMID:27419390

  2. Na4Ca3(AlO2)10:Eu2+,Mn2+荧光粉的发光特性%Photoluminescence Characteristics of Na4 Ca3(AlO2)10:Eu2+ ,Mn2+

    王雪; 田莲花


    A novel phosphor Na4Ca3(AlO2) 10:Eu2+ was prepared by solid state reaction method in a thermal-carbon reducing atmosphere. The photoluminescence(PL) properties were investigated in this paper. The excitation spectrum of Na4Ca3(AlO2) 10:Eu2+ showed two absorption bands centered at 262 nm and 320 nm respectively. The photoluminescence spectrum of Na4Ca3(AlO2) 10:Eu2+ exhibited a single emission peak centered at 441 nm, which could be attributed to 5d-4f transition of Eu + . The excitation spectrum of Na4Ca3(AlO2) 10:Eu2+ showed absorption peak at about 440 nm monitoring at 542 nm, which shows spectral overlap between emission spectrum of Na4Ca3(AlO2) 10:Eu2+. Co-doped Mn2+ with Eu2+, the photoluminescence spectra of Na4Ca3(AlO2) 10:Eu2+ were observed two peaks centered at 441 nm and 542 nm corresponding to the 5d-4f transition of Eu2+ and the d-d transition of Mn2+ , respectively. With increasing the concentration of Mn2+ ,the emission intensity of 5d-4f transition of Eu2+ at 441 nm was significantly decreased,whereas the d-d transition of Mn2+ at 542 nm was found to increase. The decay lifetime for Eu2+ was found to decrease with increasing Mn2+ dopant content, which was strong evidence for the energy transfer from Eu2+ to Mn2+ . We were also interested in investigating the energy transfer efficiency ηT of Eu2+→Mn2+ . With increasing Mn2+ dopant content, the energy transfer efficiency ηT was found to increase gradually. According to the Dexter's energy transfer formula of multipolar interaction, it was demonstrated that the energy transfer from Eu2+ to Mn2+ was due to the electric quadripole-quadripole interaction of the resonance transfer. According to the CIE chromaticity coordinates of Na4Ca3(AlO2) 10:Eu2+ , it was clearly observed that the CIE chro-maticity coordinates with the increase of Mn content shifted from blue region to white region.

  3. Coincidence detection of convergent perforant path and mossy fibre inputs by CA3 interneurons.

    Calixto, Eduardo; Galván, Emilio J; Card, J Patrick; Barrionuevo, Germán


    We performed whole-cell recordings from CA3 s. radiatum (R) and s. lacunosum-moleculare (L-M) interneurons in hippocampal slices to examine the temporal aspects of summation of converging perforant path (PP) and mossy fibre (MF) inputs. PP EPSPs were evoked from the s. lacunosum-moleculare in area CA1. MF EPSPs were evoked from the medial extent of the suprapyramidal blade of the dentate gyrus. Summation was strongly supralinear when examining PP EPSP with MF EPSP in a heterosynaptic pair at the 10 ms ISI, and linear to sublinear at longer ISIs. This pattern of nonlinearities suggests that R and L-M interneurons act as coincidence detectors for input from PP and MF. Summation at all ISIs was linear in voltage clamp mode demonstrating that nonlinearities were generated by postsynaptic voltage-dependent conductances. Supralinearity was not detected when the first EPSP in the pair was replaced by a simulated EPSP injected into the soma, suggesting that the conductances underlying the EPSP boosting were located in distal dendrites. Supralinearity was selectively eliminated with either Ni2+ (30 microm), mibefradil (10 microm) or nimodipine (15 microm), but was unaffected by QX-314. This pharmacological profile indicates that supralinearity is due to recruitment of dendritic T-type Ca2+channels by the first subthreshold EPSP in the pair. Results with the hyperpolarization-activated (Ih) channel blocker ZD 7288 (50 microm) revealed that Ih restricted the time course of supralinearity for coincidently summed EPSPs, and promoted linear to sublinear summation for asynchronous EPSPs. We conclude that coincidence detection results from the counterbalanced activation of T-type Ca2+ channels and inactivation of Ih. PMID:18388134

  4. Memory effect in spin-chain single crystal Ca3Co1.62Mn0.38O6

    Highlights: • The memory effect exists in the spin-chain single crystal Ca3Co1.62Mn0.38O6. • The memory effect in Ca3Co1.62Mn0.38O6 is associated with chemical disorder and competing interactions. • The observed memory effect can be described by the phenomenological hierarchical model. - Abstract: Amazing memory effect due to spin glass-like freezing has been illustrated in the spin-chain single crystal of Ca3Co1.62Mn0.38O6 by systematic magnetization measurements including temperature- and time-dependent magnetization curves in low fields. The observed memory effect can be described by the phenomenological hierarchical model and its origin is associated with chemical disorder and competing antiferromagnetic and ferromagnetic interactions due to introduction of Mn. Thus, Ca3Co1.62Mn0.38O6 may be considered as a candidate material for the memory storage devices

  5. Effects of Synthesis and Processing on the Thermoelectric Properties of Ca3Co4O9+δ

    Wu, NingYu; Holgate, Tim; Van Nong, Ngo;

    In the present study, Ca3Co4O9+δ was synthesized by solid-state and sol-gel reactions followed by spark plasma sintering (SPS) under different conditions such as sintering temperatures, applied pressures and ramping rates. The materials were then characterized with respect to their microstructure...

  6. The antidepressant tianeptine persistently modulates glutamate receptor currents of the hippocampal CA3 commissural associational synapse in chronically stressed rats

    Kole, MHP; Swan, L; Fuchs, E


    Recent hypotheses on the action of antidepressants imply a modulation of excitatory amino acid transmission. Here, the effects of long-term antidepressant application in rats with the drug tianeptine were examined at hippocampal CA3 commissural associational (c/a) glutamate receptor ion channels, em

  7. Evidence of the Current Collector Effect: Study of the SOFC Cathode Material Ca3Co4O9+d

    Rolle, A.; Thoréton, V.; Rozier, P.; Capoen, E.; Mentré, O.; Boukamp, B.A.; Daviero-Minaud, S.


    In the study of the performance of solid oxide fuel cell (SOFC) electrodes, the possible influence of the applied current collector is often not mentioned or recognized. In this article, as part of an optimization study of the potentially attractive Ca3Co4O9+δ cathode material (Ca349), special atten

  8. Factorizations and Physical Representations

    Revzen, M.; F. C. Khanna(Edmonton, Canada); Mann, A.; Zak, J.


    A Hilbert space in M dimensions is shown explicitly to accommodate representations that reflect the prime numbers decomposition of M. Representations that exhibit the factorization of M into two relatively prime numbers: the kq representation (J. Zak, Phys. Today, {\\bf 23} (2), 51 (1970)), and related representations termed $q_{1}q_{2}$ representations (together with their conjugates) are analysed, as well as a representation that exhibits the complete factorization of M. In this latter repre...

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

    Ruseska G.


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

  10. Representational Inquiry Competences in Science Games

    Magnussen, Rikke


    support work with genuine scientific inquiry and to meet the seventh- to tenth grade curriculum objectives for science and Danish education in Danish schools. This paper comprises a presentation of the results of a long-term empirical study done of four school classes who have played the game. The chapter...... includes studies of how students construct visual representations of the cases they investigate and how they use these representations to establish hypotheses and evidence. The term ‘Representational Inquiry Competences' is developed; it refers to the students' ability to construct, productively use......, transform and criticize visual representations as an integrated part of conducting an inquiry in the science game...

  11. Growth and polarized spectral properties of Sm3+ doped in Ca3La2(BO3)4 crystal

    Wang, Yeqing; Chen, Aixi; Tu, Chaoyang


    A Sm3+-doped Ca3La2(BO3)4 single crystal was grown by the Czochralski method. Its polarized absorption, emission spectra and fluorescence lifetime measurements were carried out at room temperature. Based on the Judd-Ofelt theory, the spectroscopic parameters Ωt (t = 2, 4, 6), radiative transition probabilities, radiative lifetime and fluorescence branching ratios were obtained. The stimulated emission cross section, the fluorescence lifetime and the quantum efficiency of the promising laser transition were also calculated and compared with other reported crystals. The results showed that Sm3+:Ca3La2(BO3)4 is a promising candidate for the orange-yellow laser emission.

  12. Electron radiation damages to dicalcium (Ca2SiO4) and tricalcium (Ca3SiO5) orthosilicates

    de Noirfontaine, Marie-Noëlle; Dunstetter, Frédéric; Courtial, Mireille; Signes-Frehel, Marcel; Wang, Guillaume; Gorse-Pomonti, Dominique


    Electron radiation damages to dicalcium silicate (Ca2SiO4) and tricalcium silicate (Ca3SiO5) are reported for the first time in this paper. With increasing flux, between 2.7 × 1017 and 2.2 × 1022 e- cm-2 s-1, decomposition into nanodomains of crystalline CaO plus an amorphous silica rich phase is first observed for both silicates, then amorphization at higher flux always for both silicates, and finally hole drilling but only for Ca3SiO5. These structural modifications are accompanied by a net reduction of Ca content under the electron beam depending on the silicate species. These radiation effects occur for values of flux and dose larger than in previously studied orthosilicates (like olivines), and much larger than in all tectosilicates.


    Ondrej Jankovsky; Stepan Huber; Sedmidubsky David; Nadherny Ladislav; Hlasek Tomas; Sofer Zdenek


    We successfully prepared Ca3Co4O9+δ . n CaZrO3 composites by a ceramic route. These composites were characterized by X-Ray diffraction, differential thermal analysis, thermogravimetric analysis and scanning electron microscopy. Moreover, transport properties (Seebeck coefficient, electrical resistivity and thermal conductivity) were measured and the thermoelectric figure of merit ZT was determined. Addition of CaZrO3 led to a suppression of thermal conductivity of the samples. A high...

  14. Increased size and stability of CA1 and CA3 place fields in HCN1 knockout mice

    Hussaini, Syed A.; Kempadoo, Kimberly A.; Thuault, Sébastien J.; Siegelbaum, Steven A.; Kandel, Eric R.


    Hippocampal CA1 and CA3 pyramidal neuron place cells encode the spatial location of an animal through localized firing patterns called “place fields”. To explore the mechanisms that control place cell firing and their relationship to spatial memory, we studied mice with enhanced spatial memory resulting from forebrain-specific knockout of the HCN1 hyperpolarization-activated cation channel. HCN1 is strongly expressed in CA1 neurons and entorhinal cortex grid cells, which provide spatial infor...

  15. Growth of Devitrite, Na2Ca3Si6O16, in Soda-Lime-Silica Glass

    Knowles, Kevin M.; Thompson, Robert P.


    This article (Knowles, K. M., Thompson, R. P. (2014), Growth of Devitrite, Na2Ca3Si6O16, in Soda?Lime?Silica Glass. Journal of the American Ceramic Society, 97: 1425?1433. doi: 10.1111/jace.12922) is the author accepted manuscript, which can also be found on the publisher's website at: ? 2014 The American Ceramic Society

  16. Spin frustration and magnetic ordering in triangular lattice antiferromagnet Ca3CoNb2O9

    Dai, Jia; Zhou, Ping; Wang, Peng-Shuai; Pang, Fei; Munsie, Tim J.; Luke, Graeme M.; Zhang, Jin-Shan; Yu, Wei-Qiang


    We synthesized a quasi-two-dimensional distorted triangular lattice antiferromagnet Ca3CoNb2O9, in which the effective spin of Co2+ is 1/2 at low temperatures, whose magnetic properties were studied by dc susceptibility and magnetization techniques. The x-ray diffraction confirms the quality of our powder samples. The large Weiss constant θCW˜ -55 K and the low Neel temperature TN˜ 1.45 K give a frustration factor f = | θCW/TN | ≈ 38, suggesting that Ca3CoNb2O9 resides in strong frustration regime. Slightly below TN, deviation between the susceptibility data under zero-field cooling (ZFC) and field cooling (FC) is observed. A new magnetic state with 1/3 of the saturate magnetization Ms is suggested in the magnetization curve at 0.46 K. Our study indicates that Ca3CoNb2O9 is an interesting material to investigate magnetism in triangular lattice antiferromagnets with weak anisotropy. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374364 and 11222433), the National Basic Research Program of China (Grant No. 2011CBA00112). Research at McMaster University supported by the Natural Sciences and Engineering Research Council. Work at North China Electric Power University supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry.

  17. Estrogen induces rapid decrease in dendritic thorns of CA3 pyramidal neurons in adult male rat hippocampus

    Modulation of hippocampal synaptic plasticity by estrogen has been attracting much attention. Thorns of thorny excrescences of CA3 hippocampal neurons are post-synaptic regions whose presynaptic partners are mossy fiber terminals. Here we demonstrated the rapid effect of estradiol on the density of thorns of thorny excrescences, by imaging Lucifer Yellow-injected CA3 neurons in adult male rat hippocampal slices. The application of 1 nM estradiol induced rapid decrease in the density of thorns on pyramidal neurons within 2 h. The estradiol-mediated decrease in the density of thorns was blocked by CNQX (AMPA receptor antagonist) and PD98059 (MAP kinase inhibitor), but not by MK-801 (NMDA receptor antagonist). ERα agonist PPT induced the same suppressive effect as that induced by estradiol on the density of thorns, but ERβ agonist DPN did not affect the density of thorns. Note that a 1 nM estradiol treatment did not affect the density of spines in the stratum radiatum and stratum oriens. A search for synaptic ERα was performed using purified RC-19 antibody. The localization of ERα (67 kDa) in the CA3 mossy fiber terminals and thorns was demonstrated using immunogold electron microscopy. These results imply that estradiol drives the signaling pathway including ERα and MAP kinase

  18. Corticosterone rapidly increases thorns of CA3 neurons via synaptic/extranuclear glucocorticoid receptor in rat hippocampus

    Miyuki Yoshiya


    We demonstrated rapid effects (~ 1 h of CORT on the density of thorns, by imaging Lucifer Yellow-injected neurons in adult male rat hippocampal slices. Thorns of thorny excrescences of CA3 hippocampal neurons are post-synaptic regions whose presynaptic partners are mossy fiber terminals. The application of CORT at 100, 500 and 1000 nM induced a rapid increase in the density of thorns in the stratum lucidum of CA3 pyramidal neurons. Co-administration of RU486, an antagonist of glucocorticoid receptor (GR, abolished the effect of CORT. Blocking a single kinase, including MAPK, PKA or PKC, suppressed CORT-induced enhancement of thorn-genesis. On the other hand, GSK-3β was not involved in the signaling of thorn-genesis. Blocking AMPA receptors suppressed the CORT effect. Expression of CA3 synaptic/extranuclear GR was demonstrated by immunogold electron microscopic analysis. From these results, stress levels of CORT (100-1000 nM might drive the rapid thorn-genesis via synaptic/extranuclear GR and multiple kinase pathways, although a role of nuclear GRs cannot be completely excluded.

  19. K(Ca3.1 channel-blockade attenuates airway pathophysiology in a sheep model of chronic asthma.

    Joanne Van Der Velden

    Full Text Available BACKGROUND: The Ca(2+-activated K(+ channel K(Ca3.1 is expressed in several structural and inflammatory airway cell types and is proposed to play an important role in the pathophysiology of asthma. The aim of the current study was to determine whether inhibition of K(Ca3.1 modifies experimental asthma in sheep. METHODOLOGY AND PRINCIPAL FINDINGS: Atopic sheep were administered either 30 mg/kg Senicapoc (ICA-17073, a selective inhibitor of the K(Ca3.1-channel, or vehicle alone (0.5% methylcellulose twice daily (orally. Both groups received fortnightly aerosol challenges with house dust mite allergen for fourteen weeks. A separate sheep group received no allergen challenges or drug treatment. In the vehicle-control group, twelve weeks of allergen challenges resulted in a 60±19% increase in resting airway resistance, and this was completely attenuated by treatment with Senicapoc (0.25±12%; n = 10, P = 0.0147. The vehicle-control group had a peak-early phase increase in lung resistance of 82±21%, and this was reduced by 58% with Senicapoc treatment (24±14%; n = 10, P = 0.0288. Senicapoc-treated sheep also demonstrated reduced airway hyperresponsiveness, requiring a significantly higher dose of carbachol to increase resistance by 100% compared to allergen-challenged vehicle-control sheep (20±5 vs. 52±18 breath-units of carbachol; n = 10, P = 0.0340. Senicapoc also significantly reduced eosinophil numbers in bronchoalveolar lavage taken 48 hours post-allergen challenge, and reduced vascular remodelling. CONCLUSIONS: These findings suggest that K(Ca3.1-activity contributes to allergen-induced airway responses, inflammation and vascular remodelling in a sheep model of asthma, and that inhibition of K(Ca3.1 may be an effective strategy for blocking allergen-induced airway inflammation and hyperresponsiveness in humans.

  20. Effects of inhaled anesthetic isoflurane on long-term potentiation of CA3 pyramidal cell afferents in vivo

    Ballesteros KA


    Full Text Available Kristen A Ballesteros,1 Angela Sikorski,2 James E Orfila,3 Joe L Martinez Jr41Department of Biology, The University of Texas at San Antonio, San Antonio, TX, USA; 2Texas A&M University Texarkana, Texarkana, TX, USA; 3University of Colorado in Denver, Denver, CO, USA; 4University of Illinois in Chicago, Chicago, IL, USAAbstract: Isoflurane is a preferred anesthetic, due to its properties that allow a precise concentration to be delivered continually during in vivo experimentation. The major mechanism of action of isoflurane is modulation of the γ-amino butyric acid (GABAA receptor-chloride channel, mediating inhibitory synaptic transmission. Animal studies have shown that isoflurane does not cause cell death, but it does inhibit cell growth and causes long-term hippocampal learning deficits. As there are no studies characterizing the effects of isoflurane on electrophysiological aspects of long-term potentiation (LTP in the hippocampus, it is important to determine whether isoflurane alters the characteristic responses of hippocampal afferents to cornu ammonis region 3 (CA3. We investigated the effects of isoflurane on adult male rats during in vivo induction of LTP, using the mossy fiber pathway, the lateral perforant pathway, the medial perforant pathway, and the commissural CA3 (cCA3 to CA3, with intracranial administration of Ringer’s solution, naloxone, RS-aminoindan-1, 5-dicarboxylic acid (AIDA, or 3-[(R-2-carboxypiperazin-4-yl]-propo-2-enyl-1-phosphonic acid (CPP. Then, we compared these responses to published electrophysiological data, using sodium pentobarbital as an anesthetic, under similar experimental conditions. Our results showed that LTP was exhibited in animals anesthetized with isoflurane under vehicle conditions. With the exception of AIDA in the lateral perforant pathway, the defining characteristics of the four pathways appeared to remain intact, except for the observation that LTP was markedly reduced in animals

  1. Learning Deep Face Representation

    Fan, Haoqiang; Cao, Zhimin; Jiang, Yuning; Yin, Qi; Doudou, Chinchilla


    Face representation is a crucial step of face recognition systems. An optimal face representation should be discriminative, robust, compact, and very easy-to-implement. While numerous hand-crafted and learning-based representations have been proposed, considerable room for improvement is still present. In this paper, we present a very easy-to-implement deep learning framework for face representation. Our method bases on a new structure of deep network (called Pyramid CNN). The proposed Pyrami...

  2. Manipulating Thermal Conductivity by Interfacial Modification of Misfit-Layered Cobaltites Ca3Co4O9

    Fujii, Susumu; Yoshiya, Masato


    The phonon thermal conductivities of misfit-layered Ca3Co4O9, Sr3Co4O9, and Ba3Co4O9 were calculated using the perturbed molecular dynamics method to clarify the impact of lattice misfit on the phonon thermal conduction in misfit-layered cobaltites. Substitution of Sr and Ba for Ca substantially modified the magnitude of the lattice misfit between the CoO2 and rock salt (RS) layers, because of the different ionic radii, increasing overall phonon thermal conductivity. Further analyses with intentionally changed atomic masses of Ca, Sr, or Ba revealed that smaller ionic radius at the Ca site in the RS layer, instead of heavier atomic mass, is a critical factor suppressing the overall thermal conductivity of Ca3Co4O9, since it determines not only the magnitude of lattice misfit but also the dynamic interference between the two layers, which governs the phonon thermal conduction in the CoO2 and RS layers. This concept was demonstrated for Sr-doped Ca3Co4O9 as an example of atomistic manipulation for better thermoelectric properties. Phonon thermal conductivities not only in the RS layer but also in the CoO2 layer were reduced by the substitution of Sr for Ca. These results provide another strategy to improve the thermal conductivity of this class of misfit cobaltites, that is, to control the thermal conductivity of the CoO2 layer responsible for electronic and thermal conductivity by atomistic manipulation in the RS layer adjacent to the CoO2 layer.

  3. Prenatal hypoxia-ischemia induces abnormalities in CA3 microstructure, potassium chloride cotransporter 2 expression and inhibitory tone

    Lauren L Jantzie


    Full Text Available Infants who suffer perinatal brain injury, including those with encephalopathy of prematurity, are prone to chronic neurological deficits including epilepsy, cognitive impairment, and behavioral problems such as anxiety, inattention and poor social interaction. These deficits, especially in combination, pose the greatest hindrance to these children becoming independent adults. Cerebral function depends on adequate development of essential inhibitory neural circuits and the appropriate amount of excitation and inhibition at specific stages of maturation. Early neuronal synaptic responses to γ-amino butyric acid (GABA are initially excitatory. During the early postnatal period, GABAAR responses switch to inhibitory with the upregulation of potassium-chloride co-transporter KCC2. With extrusion of chloride by KCC2, the Cl- reversal potential shifts and GABA and glycine responses become inhibitory. We hypothesized that prenatal hypoxic-ischemic brain injury chronically impairs the developmental upregulation of KCC2 that is essential for cerebral circuit formation. Following late gestation hypoxia-ischemia, diffusion tensor imaging in juvenile rats shows poor microstructural integrity in the hippocampal CA3 subfield, with reduced fractional anisotropy and elevated radial diffusivity. The loss of microstructure correlates with early reduced KCC2 expression on NeuN-positive pyramidal neurons, and decreased monomeric and oligomeric KCC2 protein expression in the CA3 subfield. Together with decreased IPSCs during a critical window of development, we document for the first time that prenatal transient systemic hypoxia-ischemia in rats impairs hippocampal CA3 inhibitory tone. Failure of timely development of inhibitory tone likely contributes to a lower seizure threshold and impaired cognitive function in children who suffer perinatal brain injury.

  4. Melamine Alters Glutamatergic Synaptic Transmission of CA3-CA1 Synapses Presynaptically Through Autophagy Activation in the Rat Hippocampus.

    Zhang, Hui; Wang, Hui; Xiao, Xi; Zhang, Tao


    Melamine is an industrial chemical that can cause central nervous system disorders including excitotoxicity and cognitive impairment. Its illegal use in powdered baby formula was the focus of a milk scandal in China in 2008. One of our previous studies showed that melamine impaired glutamatergic transmission in rat hippocampal CA1 pyramidal cells. However, the underlying mechanism of action of melamine is unclear, and it is unknown if the CA3-CA1 pathway is directly involved. In the present study, a whole-cell patch-clamp technique was employed to investigate the effect of melamine on the hippocampal CA3-CA1 pathway in vitro. Both the evoked excitatory postsynaptic current (eEPSC) and the paired-pulse ratio (PPR) were recorded. Furthermore, we examined whether autophagy was involved in glutamatergic transmission alterations induced by melamine. Our data showed that melamine significantly increased the amplitude of eEPSCs in a dose-dependent manner. Inhibition of the N-methyl-D-aspartic acid receptor did not prevent the increase in eEPSC amplitude. In addition, the PPR was remarkably decreased by a melamine concentration of 5 × 10(-5) g/mL. It was found that autophagy could be activated by melamine and an autophagy inhibitor, 3-MA, prevented the melamine-induced increase in eEPSC amplitude. Overall, our results show that melamine presynaptically alters glutamatergic synaptic transmission of hippocampal CA3-CA1 synapses in vitro and this is likely associated with autophagy alteration. PMID:26530910

  5. Atomic-resolution study of charge transfer and structural disorder in thermoelectric Ca3Co4O9

    Klie, Robert


    Thermoelectric oxides have attracted increasing attention due to their high thermal power and temperature stability. In particular, Ca3Co4O9, a misfit layered structure consisting of single layer hole-doped CoO2 sandwiched between insulating Ca2CoO3 rocksalt layers, exhibits figure of merit (ZT) of >1 at 1000 K.^1 It was suggested that the Seebeck-coefficient can be further increased by controlling the spin- and valence-state of the Co-ions in the CoO2 layers. This study combines aberration-corrected scanning transmission electron microscopy with electron energy loss spectroscopy (EELS) to examine the atomic and electronic structures of Ca3Co4O9. Using annular dark and bright field imaging, it will be demonstrated that the CoO2 layers are ordered, while the CoO columns in the Ca2CoO3 layer exhibit a modulation along (010). Atomic-column resolved EELS reveals that the Ca2CoO3 layers act as charge reservoirs providing mobile holes to the CoO2 layers; the structural disorder in Ca2CoO3 is responsible for the low in-plane thermal conductivity. The temperature dependence of the Co-ion spin-state as the origin for the unusually high Seebeck coefficient of Ca3O4O9 will be examined.^2 ^1 K. Fujita, et al., Jpn. J. Appl. Phys. 40 (2001), 4644--47^ ^2 Funded by: NSF CAREER Award DMR-0846748

  6. Superconducting properties of Cu1-xTlxBa2Ca3Cu4O12-y thin films

    Superconducting thin films with a predominant single phase of Cu1-xTlxBa2Ca3Cu4O12-y [Cu1-xTlx-1234] have been prepared for the first time by employing a two-step method. In this method the crystalline material was prepared from the sputtered amorphous phase by thallium treatment. This process was carried out at 900 deg. C for 1 h in an Au capsule. The amorphous phase was prepared by sputter deposition onto an SrTiO3 substrate from a stoichiometric target of composition CuBa2Ca3Cu4Ox. The films achieved after thallium treatment were aligned bi-axially along the a- and c-axes. XRD (x-ray diffraction) measurements showed a single-phase material with a c-axis lattice constant of 18.74 A. The c-axis lattice constant of Cu1-xTlx-1234 films is in between that of Cu-1234 (17.99 A) and Tl-1234 (19.11 A) superconductors. The pole figure measurements of 103 reflection of the films showed a-axis-oriented crystals with Δφ=0.8 deg. The composition of the films after EDX (energy dispersive x-ray spectroscopy) measurements was Cu0.3Tl0.7Ba2Ca3Cu4O12-y. From the resistivity measurements Tc was 110 K and Jc measurements showed a current density of 2.0x106 A cm-2 (77 K, 0 T). The preparation of Cu1-xTlx-1234 superconductor films by this method was highly reproducible. (author)

  7. Photoemission resonance study of sintered and single-crystal Bi4Ca3Sr3Cu4O16+x

    Tang, Ming; Chang, Y.; Zanoni, R.; Onellion, M.; Joynt, Robert; Huber, D. L.; Margaritondo, G.; Morris, P. A.; Bonner, W. A.; Tarascon, J. M.; Stoffel, N. G.


    We present soft x-ray photoemission spectra that probe the valence and core electronic structure of the high-Tc superconductor Bi4Ca3Sr3Cu4O16+x. The identification of spectral features was helped by the observation of the resonant behavior of a Cu-related satellite feature. The resonance occurs at photon energies near the Cu3p optical absorption edge, and affects a peak 12.5 eV below the Fermi edge. We identified this feature as a correlation satellite characteristic of Cu in the 2+ valence state. Other features observed in the spectra more than 7 eV below the Fermi edge are due to several different core levels. In particular, we observed a strong Bi5d doublet. Other core level peaks are due to the Sr4p and Ca3p orbitals, and to Bi, Sr and Ca s-orbitals. Within 7 eV of the Fermi edge, the spectra are dominated by valence states. The most important feature is the Bi4Ca3Sr3Cu4O16+x Fermi edge itself, which we observed for the first time on this, and whose existence was subsequently confirmed by several other groups. On the contrary, no edge was observed in the photoemission spectra of materials in the YBa2Cu3O7-x family. The observation of the Fermi edge has important implications for the theoretical interpretation of high-Tc superconductivity. Furthermore, it enabled us to see near-edge changes associated with the superconducting transition.

  8. Differential long-term depression in CA3 but not in dentate gyrus following low-frequency stimulation of the medial perforant path.

    Fung, Thomas K; Peloquin, Pascal; Wu, Kun; Leung, L Stan


    Synaptic plasticity may depend not only on the afferent fibers but also on the recipient structure. The medial perforant path (MPP) from the entorhinalcortex projects to both the dentate gyrus (DG) and CA3, resulting in excitatory postsynaptic potentials (EPSPs) in both areas. In this study, we showed that long-term depression (LTD) following low-frequency stimulation of MPP was found only in CA3a, a CA3 subfield, but not in DG. Field potentials were recorded and current source density (CSD) analyzed in CA3a and DG following stimulation of MPP in urethane-anesthetized rats. MPP evoked a short-latency population spike (PS) and EPSP in CA3a, phosphonovaleric acid or a nonselective group I/II metabotropic glutamate receptor (mGluR) antagonist (RS)-α-methyl-4-carboxyphenylglycine. We conclude that an NMDAR and mGluR sensitive LTD is induced in CA3 but not in the DG following low-frequency MPP stimulation in vivo, and the bi-directional synaptic plasticity in CA3 may be responsible for its behavioral functions. PMID:21190218

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

    Rossner Moritz


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

  10. Altered mitochondria and Bcl-2 expression in the hippocampal CA3 region in a rat model of acute epilepsy

    Jiyan Cheng; Lina Wu; Qiaozhi Wang; Yanfeng Gan; Guangyi Liu; Hong Yu


    BACKGROUND: Previous studies have shown that the mitochondrial structure and function are damaged in animal models of epilepsy. In addition, the Bcl-2 protein is capable of regulating mitochondrial stability.OBJECTIVE: To observe and validate changes in mitochondrial structure and Bcl-2 expression, and to analyze these characteristics in the hippocampal CA3 region of rat models of epilepsy. DESIGN, TIME AND SETTING: This randomized, controlled, animal experiment was performed at the Laboratory of Electron Microscopy and Department of Histology and Embryology, Luzhou Medical College between 2007 and 2008.MATERIALS: Coriamyrtin was provided by the Pharmacy Factory of West China University of Medical Sciences. The primary and secondary antibodies were provided by Zhongshan Goldenbridge Biotechnology, Beijing.METHODS: A total of 44 adult, male, Sprague Dawley rats were randomly divided into control (n=11) and epilepsy (n=33) groups. Rats in the epilepsy group were induced by coriamyrtin (50μg/kg), which was injected into the lateral ventricles. The rats were then observed at 3, 6, and 24 hours after epilepsy induction, with 11 rats at each time point. Epilepsy was not induced in rats from the control group.MAIN OUTCOME MEASURES: Pathological changes in the hippocampal CA3 region were observed by light microscopy; Bcl-2 expression was analyzed by immunohistochemistry; and mitochondrial changes in the hippocampus were observed under transmission electron microscopy.RESULTS: (1) The control group displayed very little Bcl-2 protein expression in the hippocampal CA3 region. However, after 3 hours of epilepsy, expression was visible. By 6 hours, expression peaked and then subsequently decreased after 24 hours, but remained higher than the control group (P<0.05). (2) Mitochondria were damaged to varying degrees in the epilepsy groups. For example, mitochondria edema, cristae space increase, and disappearance of mitochondria were apparent. Moreover, mitochondrial damage

  11. Evaluation of Ca3Co2O6 as cathode material for high-performance solid-oxide fuel cell

    Tao Wei; Yun-Hui Huang; Rui Zeng; Li-Xia Yuan; Xian-Luo Hu; Wu-Xing Zhang; Long Jiang; Jun-You Yang; Zhao-Liang Zhang


    A cobalt-based thermoelectric compound Ca3Co2O6 (CCO) has been developed as new cathode material with superior performance for intermediate-temperature (IT) solid-oxide fuel cell (SOFC). Systematic evaluation has been carried out. Measurement of thermal expansion coefficient (TEC), thermal-stress (σ) and interfacial shearing stress (τ) with the electrolyte show that CCO matches well with several commonly-used IT electrolytes. Maximum power density as high as 1.47 W cm−2 is attained at 800°C, ...

  12. Magnetic phase separation in double layer ruthenates Ca3(Ru1−x Ti x )2O7

    Jin Peng; Liu, J. Y.; J. Hu; Mao, Z. Q.; F. M. Zhang; Wu, X S


    A phase transition from metallic AFM-b antiferromagnetic state to Mott insulating G-type antiferromagnetic (G-AFM) state was found in Ca3(Ru1−x Ti x )2O7 at about x = 0.03 in our previous work. In the present, we focused on the study of the magnetic transition near the critical composition through detailed magnetization measurements. There is no intermediate magnetic phases between the AFM-b and G-AFM states, which is in contrasted to manganites where a similar magnetic phase transition takes...

  13. Lanthanides in phosphates with structure of vitlokite mineral [analog of β-Ca3(PO4)2

    Data on phosphates with structure of biogenic mineral vitlokite (analog of low-temperature modification of calcium phosphate β-Ca3(PO4)2) are analyzed. Possibility of isomorphism of cations in phosphates of such structure and formation of solid solutions with lanthanides is shown. Sol-gel method is used for synthesis of phosphates of Ca, Mg and Sm, Eu, and Gd. Characteristics of their thermal, thermal-mechanical and hydrolytic stability are determined. Results of hydrothermal and thermal tests are compared with literature data on Ca phosphate and other potential matrix materials for radioactive waste immobilization

  14. Growth kinetics of Cu1-xTlxBa2Ca3Cu4O12-y thin films

    Cu1-xTlxBa2Ca3Cu4O12-y (Cu1-xTlx-1234) thin films have been found to be very attractive candidates in the cuprate family due to their low superconductor anisotropy, long coherence length and, consequently, high Jc. The method of preparation has been reported previously, however the kinetics of their formation has not yet been studied. In this paper, we report on the growth kinetics of superconducting Cu1-xTlxBa2Ca3Cu4O12-y thin films. In the preparation, we use the amorphous phase epitaxy method, which is a thallium treatment of the amorphous phase at elevated temperatures. The amorphous phase was deposited on a SrTiO3 substrate by rf-sputtering from a stoichiometric target with a composition of CuBa2Ca3Cu4Oy. The thallium treatment of the amorphous phase was carried out in a gold capsule for 45 min. The mechanism of the growth kinetics has shown that the formation of Cu1-xTlxBa2Ca3Cu4O12-y thin films was accomplished from Cu1-xTlxBa2Ca1Cu2O8-y (Cu1-xTlx-1212) and Cu1-xTlxBa2Ca2Cu3O10-y (Cu1-xTlx-1223) by the successive introduction of CuO2 planes in these phases. We also studied the effect of the time and temperature of the thallium treatment on the growth of Cu1-xTlx-1234 films. The best synthesis temperature for Cu1-xTlx-1234 films was found to be 910 deg. C, but this phase could also be isolated as a single phase at lower temperatures (∼890 deg. C). However, the low-temperature synthesis results in a higher thallium content in the final compound. From the x-ray diffraction measurements the c-axis length was found to increase with the increase of the thallium content. The pole figure measurements of the (103) reflection of the films have shown a-axis oriented crystals with Δ φ = 0.8 deg. The observed critical temperature (Tc) for Cu1-xTlx-1212, Cu1-xTlx-1223 and Cu1-xTlx-1234 are 78 K, 103 K and 110 K respectively. Current density measurements have shown a maximum Jc∼2x106 A cm-2. (author)

  15. Discovery of a New Garnet Mineral, Ca_3Ti_2(SiAl_2)O_(12): An Alteration Phase in Allende

    Ma, Chi; Krot, Alexander N.


    During a nanomineralogy investigation of the Allende CV3 carbonaceous chondrite, a new Ti-rich silicate, Ca_3Ti_2(SiAl_2)O_(12) with the Ia-3d garnet structure, was identified in the Type B1 Ca,Al-rich inclusion (CAI) Egg-3. Field-emission SEM with EDS and electron back-scatter diffraction and electron microprobe were used to characterize the composition and structure. Synthetic Ca_3Ti_2(SiAl_2)O_(12) is not reported. We present here the natural occurrence of Ca_3Ti_2(SiA...

  16. Critical points in the Bragg glass phase of a weakly pinned crystal of Ca3Rh4Sn13

    S Sarkar; A D Thakur; C V Tomy; G Balakrishnan; D McK Paul; S Ramakrishnan; A K Grover


    New experimental data are presented on the scan rate dependence of the magnetization hysteresis width () (∝ critical current density c()) in isothermal - scans in a weakly pinned single crystal of Ca3Rh4Sn13, which displays second magnetization peak (SMP) anomaly as distinct from the peak effect (PE). We observe an interesting modulation in the field dependence of a parameter which purports to measure the dynamical annealing of the disordered bundles of vortices injected through the sample edges towards the destined equilibrium vortex state at a given . These data, in conjunction with the earlier observations made while studying the thermomagnetic history dependence in c() in the tracing of the minor hysteresis loops, imply that the partially disordered state heals towards the more ordered state between the peak field of the SMP anomaly and the onset field of the PE. The vortex phase diagram in the given crystal of Ca3Rh4Sn13 has been updated in the context of the notion of the phase coexistence of the ordered and disordered regions between the onset field of the SMP anomaly and the spinodal line located just prior to the irreversibility line. A multi-critical point and a critical point in the (, ) region of the Bragg glass phase have been marked in this phase diagram and the observed behavior is discussed in the light of recent data on multi-critical point in the vortex phase diagram in a single crystal of Nb.

  17. Effect of the nanometric scale thickness on the magnetization steps in Ca3Co2O6 thin films

    Moubah, Reda; Colis, Silviu; Ulhaq-Bouillet, Corinne; Drillon, Marc; Dinia, Aziz


    We report on the effect of the film thickness on the magnetic properties of Ca3Co2O6 films with an emphasis on the magnetization steps usually observed in the M-H curves below 10 K. Films with thicknesses between 35 and 200 nm all present two magnetic transitions at about TC1 = 22 K and TC2 = 10 K, corresponding to a 3D long range ferrimagnetic order and the transition to the formation of a frozen spin state, respectively. The magnetization curves at 10 K exhibit the expected stepped variation. However, by decreasing the thickness below a critical value of about 60 nm, no magnetization plateau is observed when the M-H curve is recorded at 2 K. Moreover, an additional transition in the susceptibility curve is observed at 45 K. These changes can be attributed to the reduced coherence length of the propagation vector along and perpendicular to the chains, and are supported by the magnetization relaxation measurements which indicate a reduction of the relaxation time. These results are helpful for understanding the origin of the magnetization steps in the one-dimensional Ca3Co2O6 cobaltite and confront the theoretical models aimed at explaining the magnetic properties in this system.

  18. Luminescence and energy transfer in Ca3Sc2Si3O12:Ce3+,Mn2+ white LED phosphors

    Expanded emission spectra ranging from green to red are reported in Ca3Sc2Si3O12 (CSS):Ce3+,Mn2+ silicate garnets. Mn2+ may occupy Ca2+ site (Mn2+(I)) to generate a yellow emission band at 574 nm or Sc3+ site (Mn2+(II)) with red emission band at 680 nm. Efficient energy transfers from the green emitting Ce3+ to both Mn2+(I) and Mn2+(II) occur upon blue excitation into Ce3+. Concentration dependence of Mn2+ emission is analyzed based on Ce3+–Mn2+ energy transfer, steady state rate equations, and fluorescence lifetimes. Energy transfer efficiency (ηT) and rate (W) are calculated with values as high as 45% and 14.01×106 s−1, respectively. - Highlights: ► Mn2+ can occupy Ca2+ site to generate a yellow emission band at 574 nm in Ca3Sc2Si3O12 (CSS). ► Mn2+ can also occupy Sc3+ site to generate a red emission band at 680 nm in CSS. ► Remarkable energy transfers (ETs) from Ce3+ to Mn2+ occur upon blue excitation into Ce3+ in CSS. ► Full color emissions are obtained based on Ce3+–Mn2+ ETs in CSS:Ce3+,Mn2+.

  19. Microstructure and Thermoelectric Properties of Bi- and Cu-Substituted Ca3Co4O9 Oxides

    Haoshan Hao; Limin Zhao; Xing Hu


    Bi- and Cu-substituted Ca3Co4O9 samples were prepared by conventional solid-state reaction method and the effect of element substitution on the microstructures and thermoelectric properties was investigated. Partial substitution of Cu for Co leads to an increase in electrical conductivity and a decrease in Seebeck coefficient due to the rise of hole concentration. The microstructure of Cu-substituted sample is almost unchanged compared with undoped Ca3Co4O9. On the other hand, partial substitution of Bi for Ca gives rise to a significant increase in the grain size, and c-axis-oriented structure can be formed in Ca2.7Bi0.3Co4O9, resulting in an obvious increase in electrical conductivity. Cu and Bi co-substitution further increases the grain growth and the electrical conductivity of Ca2.7Bi0.3Co3.7Cu0.3O9. Thus, Cu and Bi co-substitution samples possess the optimal thermoelectric performance at high temperature and the highest value of power factor can reach 3.1×10-4 Wm-1·K-2 at 1000 K.

  20. Spectral variations of Ca3Sc2Si3O12:Ce phosphors via substitution and energy transfer

    LIU Yuanhong; ZHUANG Weidong; LIU Ronghui; HU Yunsheng; HE Huaqiang; ZHANG Shusheng; GAO Wei


    The luminescence intensity of emission peak at around 525 nm decreased in the Ce3+ and Er3+ co-doped Ca3Sc2Si3O12 phosphors.Mg2+ ion,which was likely incorporated into the Sc3+ position of the host crystal,was co-doped to adjust the crystal field and compensate for the excess positive charge due to the doping of Ce3+.The green emission belonged to the 5d→4f transition of Ce3+ moved toward longer wavelength by addition of Mg2+ in Ce3+ and Er3+ co-doped Ca3Sc2Si3O12 phosphor,which could increase the brightness of the phosphor.However,the position of weakening of luminescence intensity at around 525 nm remained basically unchanged by increasing the amount of Mg2+.The results showed that the weakening of luminescence intensity at around 525 nm caused by the absorption of Er3+,which had littleinfluence on the environment of the crystal field.

  1. The Benefit of Multitask Representation Learning

    Maurer, Andreas; Pontil, Massimiliano; Romera-Paredes, Bernardino


    We discuss a general method to learn data representations from multiple tasks. We provide a justification for this method in both settings of multitask learning and learning-to-learn. The method is illustrated in detail in the special case of linear feature learning. Conditions on the theoretical advantage offered by multitask representation learning over independent task learning are established. In particular, focusing on the important example of half-space learning, we derive the regime in...

  2. Rational Expectations Equilibria: Existence and Representation

    Bhowmik, Anuj; Cao, Jiling


    In this paper, we continue to explore the equilibrium theory under ambiguity. For a model of a pure exchange and asymmetric information economy with a measure space of agents whose exogenous uncertainty is described by a complete probability space, we establish a representation theorem for a Bayesian or maximin rational expectations equilibrium allocation in terms of a state-wise Walrasian equilibrium allocation. This result also strengthens the theorems on the existence and representation of...

  3. A simple method for the normal pressure synthesis of Cu1-xTl xBa2Ca3Cu4O12-δ superconductor

    A very simple method for the direct synthesis of Cu1-xTl xBa2Ca3Cu4O12-δ (Cu1-xTl x-1234) superconductor is reported. A predominant single phase Cu1-xTl x-1234 is achieved by the solid state reaction of Ba(NO3)2, CaCO3 and Cu(CN) at first stage and with appropriate amount of Tl2O3 at the second stage. These materials were fired twice for 24 h at 880 deg C followed by intermediate grinding. Thoroughly ground and fired material was mixed with Tl2O3 in appropriate amount and pellets were made by applying a pressure of 5 tons. Pellets were wrapped in an aluminum foil and sintered at 880 deg C for 3-30 min. A predominantly single phase of Cu1-xTl xBa2Ca3Cu4O12-δ was achieved with an inclusion of unknown impurity. The resistivity measurements established the onset temperature of superconductivity [T c (onset)] at 120 K and zero resistivity critical temperature [T c(R = 0)] at 106 K. Bulk superconductivity was also confirmed by ac-magnetic susceptibility measurements. The surface of the samples was analyzed by electron microscopy and their composition by energy dispersive X-ray spectroscopy (EDX) measurements. For optimizing the carriers in the final compound, post-annealing experiments were carried out in the flowing nitrogen atmosphere. For the study of the doping mechanisms, in the post-annealed samples, the phonon modes of Cu1-xTl x-1234 were investigated by infrared absorption measurements. The absorption mode of O δ [O3] atoms decreased in intensity after the post-annealing and the apical oxygen modes were softened to lower wave numbers. The softening of these phonon modes suggested the reduction of thallium from Tl3+ to Tl1+; which resulted in an increase of [T c(R = 0)] of the material

  4. Deposition, structure, physical and invitro characteristics of Ag-doped β-Ca3(PO4)2/chitosan hybrid composite coatings on Titanium metal.

    Singh, Ram Kishore; Awasthi, Sharad; Dhayalan, Arunkumar; Ferreira, J M F; Kannan, S


    Pure and five silver-doped (0-5Ag) β-tricalcium phosphate [β-TCP, β-Ca3(PO4)2]/chitosan composite coatings were deposited on Titanium (Ti) substrates and their properties that are relevant for applications in hard tissue replacements were assessed. Silver, β-TCP and chitosan were combined to profit from their salient and complementary antibacterial and biocompatible features.The β-Ca3(PO4)2 powders were synthesized by co-precipitation. The characterization results confirmed the Ag(+) occupancy at the crystal lattice of β-Ca3(PO4)2. The Ag-dopedβ-Ca3(PO4)2/chitosan composite coatings deposited by electrophoresis showed good antibacterial activity and exhibited negative cytotoxic effects towards the human osteosarcoma cell line MG-63. The morphology of the coatings was observed by SEM and their efficiency against corrosion of metallic substrates was determined through potentiodynamic polarization tests. PMID:26952474

  5. Effect of nitric oxide synthase inhibition on long-term potentiation at associational-commissural and mossy fibre synapses on CA3 pyramidal neurones.

    Nicolarakis, P. J.; Lin, Y Q; Bennett, M. R.


    1. The sensitivity of long-term potentiation (LTP) to nitric oxide synthase (NOS) inhibition was determined for two synaptic input systems onto CA3 pyramidal neurones the LTP of which display differential sensitivity to N-methyl-D-aspartate (NMDA) receptor antagonists: the fimbrial input which activates the associational-commissural synapses on the distal apical dendrites and the mossy fibre input which synapses on the proximal apical dendrites of CA3 pyramidal neurones. 2. Following high-fre...

  6. Preliminary X-ray crystallographic analysis of β-carbonic anhydrase psCA3 from Pseudomonas aeruginosa

    Two crystal forms of β-carbonic anhydrase psCA3 from P. aeruginosa were grown. Crystal form A belonged to space group P212121, with unit-cell parameters a = 81.9, b = 84.9, c = 124.2 Å, and diffracted X-rays to 2.9 Å resolution; crystal form B belonged to space group P21212, with unit-cell parameters a = 69.9, b = 77.7, c = 88.5 Å, and diffracted X-rays to 3.0 Å resolution. Pseudomonas aeruginosa is a Gram-negative bacterium that causes life-threatening infections in susceptible individuals and is resistant to most clinically available antimicrobials. Genomic and proteomic studies have identified three genes, pa0102, pa2053 and pa4676, in P. aeruginosa PAO1 encoding three functional β-carbonic anhydrases (β-CAs): psCA1, psCA2 and psCA3, respectively. These β-CAs could serve as novel antimicrobial drug targets for this pathogen. X-ray crystallographic structural studies have been initiated to characterize the structure and function of these proteins. This communication describes the production of two crystal forms (A and B) of β-CA psCA3. Form A diffracted to a resolution of 2.9 Å; it belonged to space group P212121, with unit-cell parameters a = 81.9, b = 84.9, c = 124.2 Å, and had a calculated Matthews coefficient of 2.23 Å3 Da−1 assuming four molecules in the crystallographic asymmetric unit. Form B diffracted to a resolution of 3.0 Å; it belonged to space group P21212, with unit-cell parameters a = 69.9, b = 77.7, c = 88.5 Å, and had a calculated Matthews coefficient of 2.48 Å3 Da−1 assuming two molecules in the crystallographic asymmetric unit. Preliminary molecular-replacement solutions have been determined with the PHENIX AutoMR wizard and refinement of both crystal forms is currently in progress

  7. Representation recovers information

    Thornton, Chris


    Early agreement within cognitive science on the topic of representation has now given way to a combination of positions. Some question the significance of representation in cognition. Others continue to argue in favor, but the case has not been demonstrated in any formal way. The present paper sets out a framework in which the value of representation-use can be mathematically measured, albeit in a broadly sensory context rather than a specifically cognitive one. Key to the approach is the use...




    For focused applications with limited user and use application communities, XML can be the right choice for representation. It is easy to use, maintain, and extend and enjoys wide support in commercial and research sectors. When the knowledge and information to be represented is object-based and use of that knowledge and information is a high priority, then XML-based representation should be considered. This paper discusses some of the issues involved in using XML-based representation and presents an example application that successfully uses an XML-based representation.

  9. Piezoelectric Ca3NbGa3Si2O14 crystal: crystal growth, piezoelectric and acoustic properties

    Roshchupkin, Dmitry; Ortega, Luc; Plotitcyna, Olga; Erko, Alexei; Zizak, Ivo; Vadilonga, Simone; Irzhak, Dmitry; Emelin, Evgenii; Buzanov, Oleg; Leitenberger, Wolfram


    Ca3NbGa3Si2O14 (CNGS), a five-component crystal of lanthanum-gallium silicate group, was grown by the Czochralski method. The parameters of the elementary unit cell of the crystal were measured by powder diffraction. The independent piezoelectric strain coefficients d{}_{11} and d_{14} were determined by the triple-axis X-ray diffraction in the Bragg and Laue geometries. Excitation and propagation of surface acoustic waves (SAW) were studied by high-resolution X-ray diffraction at BESSY II synchrotron radiation source. The velocity of SAW propagation and power flow angles in the Y-, X- and yxl/{+}36°-cuts of the CNGS crystal were determined from the analysis of the diffraction spectra. The CNGS crystal was found practically isotropic by its acoustic properties.

  10. Neural stem cell activation and glial proliferation in the hippocampal CA3 region of posttraumatic epileptic rats

    Yuanxiang Lin; Kun Lin; Dezhi Kang; Feng Wang


    The present study observed the dynamic expression of CD133, nuclear factor-κB and glial fibrillary acidic protein in the hippocampal CA3 area of the experimental posttraumatic epilepsy rats to investigate whether gliosis occurs after posttraumatic epilepsy. CD133 and nuclear factor-κB expression was increased at 1 day after posttraumatic epilepsy, peaked at 7 days, and gradually decreased up to 14 days, as seen by double-immunohistochemical staining. Glial fibrillary acidic protein/nuclear factor-κB double-labeled cells increased with time and peaked at 14 days after posttraumatic epilepsy. Results show that activation of hippocampal neural stem cells and glial proliferation after posttraumatic epilepsy-induced oxidative stress increases hippocampal glial cell density.

  11. Evaluation of Ca3Co2O6 as cathode material for high-performance solid-oxide fuel cell.

    Wei, Tao; Huang, Yun-Hui; Zeng, Rui; Yuan, Li-Xia; Hu, Xian-Luo; Zhang, Wu-Xing; Jiang, Long; Yang, Jun-You; Zhang, Zhao-Liang


    A cobalt-based thermoelectric compound Ca(3)Co(2)O(6) (CCO) has been developed as new cathode material with superior performance for intermediate-temperature (IT) solid-oxide fuel cell (SOFC). Systematic evaluation has been carried out. Measurement of thermal expansion coefficient (TEC), thermal-stress (σ) and interfacial shearing stress (τ) with the electrolyte show that CCO matches well with several commonly-used IT electrolytes. Maximum power density as high as 1.47 W cm(-2) is attained at 800°C, and an additional thermoelectric voltage of 11.7 mV is detected. The superior electrochemical performance, thermoelectric effect, and comparable thermal and mechanical behaviors with the electrolytes make CCO to be a promising cathode material for SOFC. PMID:23350032

  12. Structural and magnetic anomalies among the spin-chain compounds, Ca3Co1+Ir1-O6

    S Rayaprol; Kausik Sengupta; E V Sampathkumaran


    The results of X-ray diffraction, and ac and dc magnetisation as a function of temperature are reported for a new class of spin-chain oxides, Ca3Co1+Ir1-O6. While the = 0.0, 0.3, 0.5 and 1.0 are found to form in the K4CdCl6-derived rhombhohedral (space group $\\bar{3}$) structure, the = 0.7 composition is found to undergo a monoclinic distortion in contrast to a literature report. Apparently, the change in the crystal symmetry with x manifests itself as a change in the sign of paramagnetic Curie temperature for this composition as though magnetic coupling sensitively depends on such crystallographic distortions. All the compositions exhibit spin-glass anomalies with an unusually large frequency dependence of the peak temperature in susceptibility in a temperature range below 50 K, interestingly obeying Vogel-Fulcher relationship even for the stoichiometric compounds.

  13. Size and receptor density of glutamatergic synapses: a viewpoint from left-right asymmetry of CA3-CA1 connections

    Yoshiaki Shinohara


    Full Text Available Synaptic plasticity is considered to be the main mechanism for learning and memory. Excitatory synapses in the cerebral cortex and hippocampus undergo plastic changes during development and in response to electric stimulation. It is widely accepted that this process is mediated by insertion and elimination of various glutamate receptors. In a series of recent investigations on left-right asymmetry of hippocampal CA3-CA1 synapses, glutamate receptor subunits have been found to have distinctive expression patterns that depend on the postsynaptic density (PSD area. Particularly notable are the GluR1 AMPA receptor subunit and NR2B NMDA receptor subunit, where receptor density has either a supra-linear (GluR1 AMPA or inverse (NR2B NMDAR relationship to the PSD area. We review current understanding of structural and physiological synaptic plasticity and propose a scheme to classify receptor subtypes by their expression pattern with respect to PSD area.

  14. Effect of linearly polarized light on metamagnetic phase transition in Ca3 Mn2 Ge3O12

    It has been found that the field H1 of metamagnetic phase transitions in Ca3 Mn2 Ge3O12 garnet changes when the crystal is illuminated with linearly polarized light. The value of H1 decreases under illumination with the light polarization Εparallel [110] and it increases in the case of the light polarization Ε parallel [110]. The difference in the transition fields in these two cases was about 100 Oe at temperature T = 7 K when H1 approx 31,2 k Oe in an unexposed crystal. The change of the field of the metamagnetic phase transition is attributed to the light induction of the magnetic moment whose value and direction depend on polarization of induced light

  15. Site selective spectroscopy and crystal field analysis of Er3+ in Ca3Ga2Ge3O12 garnet

    A detailed study of the optical spectroscopy of Er3+ in Ca3Ga2Ge3O12 crystals is reported. Several site selective techniques were employed (absorption, luminescence, excitation and up-conversion). The combined use of these techniques allowed the separation and classification of the observed spectral lines. Six different Er3+ optical centres are observed. The energy level analysis was performed using a parametric Hamiltonian for the 4f11 electronic configuration of Er3+ in a D2 symmetry site. A set of parameters was obtained by fitting calculated to experimental energy levels for each identified centre. Differences among centres were analysed and related to the different charge compensating mechanisms. (author)

  16. Effects of Lu and Ni Substitution on Thermoelectric Properties of Ca3Co4O9+δ

    Yang, Wenchao; Qian, Haoji; Gan, Jinyu; Wei, Wei; Wang, Zhihe; Tang, Guodong


    Effects of (Lu, Ni) co-doping on the thermoelectric properties of Ca3Co4O9+δ (CCO) have been systematically investigated from 20 K to 350 K. The electrical resistivity and thermopower of (Lu, Ni) co-doped samples increase, while their thermal conductivity is significantly depressed as compared to that of pristine CCO. The figure of merit (ZT) of co-doped samples is higher than those of Lu-doped samples and pristine CCO. A maximum ZT of 0.0185 is achieved at 350 K for Ca2.9Lu0.1Co3.9Ni0.1O9+δ . We demonstrate that the simultaneous increase of spin entropy and phonon scattering induced by (Lu, Ni) co-doping boosts ZT of CCO. This study indicates that (Lu, Ni) co-doping may promise an effective way to improve thermoelectric properties of the CCO system.

  17. Flux pinning in Tl1-xCxBa2Ca3Cu4O12-δ superconductor

    The dissipation mechanism in Tl1-xCxBa2Ca3Cu4O12-δ (x = 0, 0.25, 0.5 and 0.75) superconductor under the influence of external magnetic fields have been studied. The sample with x = 0.25 have shown strong flux pinning characteristic as compared to the Tl1-xCx-1234 (x = 0, 0.5 and 0.75) samples. The scanning electron micrographs of Tl1-xCx-1234 shows well connected grains in x = 0 and 0.25 samples. Whereas, x = 0.5 and 0.75 samples have relatively poor grain morphology, which shows that the source of pinning in Tl0.75C0.25-1234 sample is intrinsic one. The transition width data was also fitted to the thermally activated flux flow model. The apical phonon modes of vibrations were studied through FTIR absorption measurements.

  18. Modifications in the frustrated magnetism, oxidation state of Co and magnetoelectric coupling effects induced by a partial replacement of Ca by Gd in the spin-chain compound Ca3Co2O6

    We have systematically investigated the influence of the gradual replacement of Ca by Gd on the magnetic and complex dielectric properties of the well-known geometrically frustrated spin-chain system Ca3Co2O6 (TN = 24 K with additional magnetic transitions below 12 K), by studying the series Ca3−xGdxCo2O6 (x ≤ 0.7), down to 1.8 K. Heat-capacity measurements establish that the reduction of TN with Gd substitution is much less compared to that by Y substitution. The magnetic moment data reveal that there are changes in the oxidation state of Co as well, unlike for Y substitution, beyond x = 0.2. Thus, despite being isovalent, both these substitutions interestingly differ in changing these magnetic properties in these oxides. We propose that the valence electrons of Y and those of R ions play different roles in deciding the magnetic characteristics of these mixed oxides. It is observed that a small amount (x = 0.3) of Gd substitution for Ca is enough to suppress glassy ac magnetic susceptibility behavior for the peak around 12 K. An additional low-temperature magnetic anomaly close to 5 K gets more prominent with increasing Gd concentration as revealed by heat-capacity data. Trends in temperature dependence of complex dielectric behavior were also tracked with varying composition and a frequency dependence is observed, not only for the transition in the region around 10 K (for some compositions), but also for the 5 K transition which is well resolved for a higher concentration of Gd. Thus, the Gd-substituted Ca3Co2O6 series is shown to reveal interesting magnetic and dielectric behaviors of this family of oxides. (paper)

  19. K(Ca)2 and k(ca)3 channels in learning and memory processes, and neurodegeneration.

    Kuiper, Els F E; Nelemans, Ad; Luiten, Paul; Nijholt, Ingrid; Dolga, Amalia; Eisel, Uli


    Calcium-activated potassium (K(Ca)) channels are present throughout the central nervous system as well as many peripheral tissues. Activation of K(Ca) channels contribute to maintenance of the neuronal membrane potential and was shown to underlie the afterhyperpolarization (AHP) that regulates action potential firing and limits the firing frequency of repetitive action potentials. Different subtypes of K(Ca) channels were anticipated on the basis of their physiological and pharmacological profiles, and cloning revealed two well defined but phylogenetic distantly related groups of channels. The group subject of this review includes both the small conductance K(Ca)2 channels (K(Ca)2.1, K(Ca)2.2, and K(Ca)2.3) and the intermediate-conductance (K(Ca)3.1) channel. These channels are activated by submicromolar intracellular Ca(2+) concentrations and are voltage independent. Of all K(Ca) channels only the K(Ca)2 channels can be potently but differentially blocked by the bee-venom apamin. In the past few years modulation of K(Ca) channel activation revealed new roles for K(Ca)2 channels in controlling dendritic excitability, synaptic functioning, and synaptic plasticity. Furthermore, K(Ca)2 channels appeared to be involved in neurodegeneration, and learning and memory processes. In this review, we focus on the role of K(Ca)2 and K(Ca)3 channels in these latter mechanisms with emphasis on learning and memory, Alzheimer's disease and on the interplay between neuroinflammation and different neurotransmitters/neuromodulators, their signaling components and K(Ca) channel activation. PMID:22701424

  20. Some Representation Theorems for Recovering Contraction Relations

    Ping Hou


    One of the important topics in the study of contraction inference relations is to establish the representation theorems for them. Various methods have been employed for giving representation of a broad class of contraction operations.However, there was not any canonical approach to dealing with the representation results for the contraction relations in the literature. Recently, in order to obtain the representation result for recovering contraction inference relations satisfying the condition weak conjunctive inclusion (wci), a notion of an image structure associated with the canonical epistemic state has been introduced. Based on the image structure, this paper establishes three representation results for recovering contraction inference relations which satisfy the conditions CL, CR1 and DR* respectively by the standard epistemic AGM states. A unique technique and uniform proofs to represent these contraction relations are adopted, which could overcome the core objection in previous description of contraction relations. The paper shows as well that the image structure and canonical epistemic states can be used not only to get the representation result for wci-recovering contraction relation, but also to provide semantic characterizations for a wide range of recovering contraction relations.

  1. Spatially variant morphological restoration and skeleton representation.

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


    The theory of spatially variant (SV) mathematical morphology is used to extend and analyze two important image processing applications: morphological image restoration and skeleton representation of binary images. For morphological image restoration, we propose the SV alternating sequential filters and SV median filters. We establish the relation of SV median filters to the basic SV morphological operators (i.e., SV erosions and SV dilations). For skeleton representation, we present a general framework for the SV morphological skeleton representation of binary images. We study the properties of the SV morphological skeleton representation and derive conditions for its invertibility. We also develop an algorithm for the implementation of the SV morphological skeleton representation of binary images. The latter algorithm is based on the optimal construction of the SV structuring element mapping designed to minimize the cardinality of the SV morphological skeleton representation. Experimental results show the dramatic improvement in the performance of the SV morphological restoration and SV morphological skeleton representation algorithms in comparison to their translation-invariant counterparts. PMID:17076415

  2. Effect of acetylcholine receptors on the pain-related electrical activities in the hippocampal CA3 region of morphine-addicted rats

    Guan Zeng Li


    Full Text Available Objective(s:To determine the effect of acetylcholine (ACh, pilocarpine, and atropine on pain evoked responses of pain excited neurons (PEN and pain inhibited neurons (PIN in hippocampal CA3 region of morphine addicted rats. Materials and Methods:Female Wistar rats, weighing between 230-260 g were used in this study. Morphine addicted rats were generated by subcutaneous injection of increasing concentrations of morphine hydrochloride for six days. Trains of electrical impulses applied to the sciatic nerve were used as noxious stimulation and the evoked electrical activities of PEN or PIN in hippocampal CA3 area were recorded using extracellular electrophysiological recording techniques in hippocampal slices. The effect of acetylcholine receptor stimulation byACh, the muscarinic agonist pilocarpine, and the muscarinic antagonist atropine on the pain evoked responses of pain related electrical activities was analyzed in hippocampal CA3 area of morphine addicted rats. Results:Intra-CA3 microinjection of ACh (2 μg/1 μl or pilocarpine (2 μg/1 μl decreased the discharge frequency and prolonged the firing latency of PEN, but increased the discharge frequency and shortened the firing inhibitory duration (ID of PIN. The intra-CA3 administration of atropine (0.5 μg/1 μl produced opposite effect. The peak activity of cholinergic modulators was 2 to 4 min later in morphine addicted rats compared to peak activity previously observed in normal rats. Conclusion: ACh dependent modulation of noxious stimulation exists in hippocampal CA3 area of morphine addicted rats. Morphine treatment may shift the sensitivity of pain related neurons towards a delayed response to muscarinergic neurotransmission in hippocampal CA3 region.

  3. The neuron-astrocyte-microglia triad involvement in neuroinflammaging mechanisms in the CA3 hippocampus of memory-impaired aged rats.

    Lana, Daniele; Iovino, Ludovica; Nosi, Daniele; Wenk, Gary L; Giovannini, Maria Grazia


    We examined the effects of inflammaging on memory encoding, and qualitative and quantitative modifications on proinflammatory proteins, apoptosis, neurodegeneration and morphological changes of neuron-astrocyte-microglia triads in CA3 Stratum Pyramidale (SP), Stratum Lucidum (SL) and Stratum Radiatum (SR) of young (3months) and aged rats (20months). Aged rats showed short-term memory impairments in the inhibitory avoidance task, increased expression of iNOS and activation of p38MAPK in SP, increase of apoptotic neurons in SP and of ectopic neurons in SL, and decrease of CA3 pyramidal neurons. The number of astrocytes and their branches length decreased in the three CA3 subregions of aged rats, with morphological signs of clasmatodendrosis. Total and activated microglia increased in the three CA3 subregions of aged rats. In aged rats CA3, astrocytes surrounded ectopic degenerating neurons forming "micro scars" around them. Astrocyte branches infiltrated the neuronal cell body, and, together with activated microglia formed "triads". In the triads, significantly more numerous in CA3 SL and SR of aged rats, astrocytes and microglia cooperated in fragmentation and phagocytosis of ectopic neurons. Inflammaging-induced modifications of astrocytes and microglia in CA3 of aged rats may help clearing neuronal debris derived from low-grade inflammation and apoptosis. These events might be common mechanisms underlying many neurodegenerative processes. The frequency to which they appear might depend upon, or might be the cause of, the burden and severity of neurodegeneration. Targeting the triads may represent a therapeutic strategy which may control inflammatory processes and spread of further cellular damage to neighboring cells. PMID:27466072

  4. Evaluation of Ca3(Co,M2O6 (M=Co, Fe, Mn, Ni as new cathode materials for solid-oxide fuel cells

    Fushao Li


    Full Text Available Series compounds Ca3(Co0.9M0.12O6 (M=Co, Fe, Mn, Ni with hexagonal crystal structure were prepared by sol–gel route as the cathode materials for solid oxide fuel cells (SOFCs. Effects of the varied atomic compositions on the structure, electrical conductivity, thermal expansion and electrochemical performance were systematically evaluated. Experimental results showed that the lattice parameters of Ca3(Co0.9Fe0.12O6 and Ca3(Co0.9Mn0.12O6 were both expanded to certain degree. Electron-doping and hole-doping effects were expected in Ca3(Co0.9Mn0.12O6 and Ca3(Co0.9Ni0.12O6 respectively according to the chemical states of constituent elements and thermal-activated behavior of electrical conductivity. Thermal expansion coefficients (TEC of Ca3(Co0.9M0.12O6 were measured to be distributed around 16×10−6 K−1, and compositional elements of Fe, Mn, and Ni were especially beneficial for alleviation of the thermal expansion problem of cathode materials. By using Ca3(Co0.9M0.12O6 as the cathodes operated at 800 °C, the interfacial area-specific resistance varied in the order of M=CoCa3(Co0.9Fe0.12O6 showed the best electrochemical performance and the power density as high as ca. 500 mW cm−2 at 800 °C achieved in the single cell with La0.8Sr0.2Ga0.83Mg0.17O2.815 as electrolyte and Ni–Ce0.8Sm0.2O1.9 as anode. Ca3(Co0.9M0.12O6 (M=Co, Fe, Mn, Ni can be used as the cost-effective cathode materials for SOFCs.

  5. Adolescent mice show anxiety- and aggressive-like behavior and the reduction of long-term potentiation in mossy fiber-CA3 synapses after neonatal maternal separation.

    Shin, S Y; Han, S H; Woo, R-S; Jang, S H; Min, S S


    Exposure to maternal separation (MS) during early life is an identified risk factor for emotional disorders such as anxiety and depression later in life. This study investigated the effects of neonatal MS on the behavior and long-term potentiation (LTP) as well as basic synaptic transmission at hippocampal CA3-CA1 and mossy fiber (MF)-CA3 synapses in adolescent mice for 19days. When mice were adolescents, we measured depression, learning, memory, anxious and aggressive behavior using the forced swimming test (FST), Y-maze, Morris water maze (MWM), elevated plus maze (EPM), three consecutive days of the open field test, the social interaction test, the tube-dominance test and the resident-intruder test. The results showed that there was no difference in FST, Y-maze, and MWM performance. However, MS mice showed more anxiety-like behavior in the EPM test and aggressive-like behavior in the tube-dominance and resident-intruder tests. In addition, the magnitude of LTP and release probability in the MF-CA3 synapses was reduced in the MS group but not in the CA3-CA1 synapse. Our results indicate that early life stress due to MS may induce anxiety- and aggressive-like behavior during adolescence, and these effects are associated with synaptic plasticity at the hippocampal MF-CA3 synapses. PMID:26733385

  6. Mechanoluminescence, thermoluminescence, photoluminescence studies on Ca3 Y2 Si3 O12 :RE(3+) (RE(3+) = Dy(3+) and Eu(3+) ) phosphors.

    Kadukar, Monali R; Yawalkar, P W; Choithrani, Renu; Dhoble, S J


    Dy(3+) and Eu(3+) activated Ca3 Y2 Si3 O12 phosphors were synthesized by the solid-state synthesis method. The phosphors were characterized by X-ray diffraction (XRD), mechanoluminescence (ML), thermoluminescence (TL) and photoluminescence (PL) to determine structure and luminescence. For ML glow curves, only one peak was observed, as only one type of luminescence centre was formed during irradiation. The Ca3 Y2 Si3 O12 :Dy(3+) TL glow curve showed a single peak at 151.55°C and the Ca3 Y2 Si3 O12 :Eu(3+) TL glow curve peaked at 323°C with a small peak at 192°C, indicating that two types of traps were activated. The trapping parameters for both the samples were calculated using Chen's peak shape method. Dy(3+) -activated Ca3 Y2 Si3 O12 showed emission at 482 and 574 nm when excited by a 351 nm excitation wavelength, whereas the Eu(3+) -activated Ca3 Y2 Si3 O12 phosphor PL emission spectra showed emission peaks at 613 nm, 591 nm, 580 nm when excited at 395 nm wavelength. When excited at 466 nm, prominent emission peaks were observed at their respective positions with very slight shifts. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25807925

  7. Irreducible finite-dimensional representations of equivariant map algebras

    Neher, Erhard; Senesi, Prasad


    Suppose a finite group acts on an algebraic variety X and a finite-dimensional semisimple Lie algebra g. The corresponding equivariant map algebra is the Lie algebra M of equivariant regular maps from X to g. We classify the irreducible finite-dimensional representations of these algebras. In particular, we show that all such representations are tensor products of evaluation representations and one-dimensional representations, and we establish conditions ensuring that they are all evaluation representations. For example, this is always the case if M is perfect. Our results can be applied to multiloop algebras, current algebras, the Onsager algebra, and the tetrahedron algebra. Doing so, we easily recover the known classifications of irreducible finite-dimensional representations of these algebras. Moreover, we obtain previously unknown classifications of irreducible finite-dimensional representations of other types of equivariant map algebras, such as the generalized Onsager algebra.

  8. A New Method for Knowledge Representation in Expert System's (XMLKR)

    Bahrami, Mehdi


    Knowledge representation it is an essential section of a Expert Systems, Because in this section we have a framework to establish an expert system then we can modeling and use by this to design an expert system. Many method it is exist for knowledge representation but each method have problems, in this paper we introduce a new method of object oriented by XML language as XMLKR to knowledge representation, and we want to discuss advantage and disadvantage of this method.

  9. Indecomposable representations for parabose algebra

    A general study of the representations of the graded Lie algebra of parabose oscillators is given. Besides realizing the standard representations, we also find some interesting indecomposable (not fully reducible) representations. (author)

  10. First-principles study of the electronic and magnetic structures of the tetragonal and orthorhombic phases of Ca3Mn2O7

    Matar, S. F.; Eyert, V.; Villesuzanne, A.; Whangbo, M.-H.


    On the basis of density functional theory electronic band structure calculations using the augmented spherical wave method, the electronic and magnetic properties of the orthorhombic and tetragonal phases of Ca3Mn2O7 were investigated and the spin exchange interactions of the orthorhombic phase were analyzed. Our calculations show that the magnetic insulating states are more stable than the nonmagnetic metallic state for both polymorphs of Ca3Mn2O7 , the orthorhombic phase is more stable than the tetragonal phase, and the ground state of the orthorhombic phase is antiferromagnetic. The total energies calculated for the three spin states of the orthorhombic phase of Ca3Mn2O7 led to estimates of the spin exchange interactions Jnn=-3.36meV and Jnnn=-0.06meV . The accuracy of these estimates was tested by calculating the Curie-Weiss temperature within the mean-field approximation.

  11. Polarized spectra calculation and continuous wave laser operation of Yb-doped disordered Ca3La2(BO3)4 crystal

    Wang, Yeqing; Chen, Aixi; You, Zhenyu; Tu, Chaoyang


    A notable disorder crystal Yb:Ca3La2(BO3)4 crystal with Yb3+ ion doping concentration of 10 at.% was grown by the Czochralski method. The polarized absorption, polarized emission, and polarized gain cross sections were systematically calculated. The laser operations were investigated with Yb:Ca3La2(BO3)4 crystals cut along the a, b, and c crystallographic axes. The highest output power of 3.88 W was obtained by using the b-cut Yb:Ca3La2(BO3)4 crystal, with a slope efficiency of 62%. Additionally, it was confirmed that the output laser spectra were largely dependent on the output coupler.

  12. Effect of atomic disorder and Ce doping on superconductivity of Ca3Rh4Sn13 : Electric transport properties under high pressure

    Ślebarski, A.; Goraus, J.; Maśka, M. M.; Witas, P.; Fijałkowski, M.; Wolowiec, C. T.; Fang, Y.; Maple, M. B.


    We report the observation of a superconducting state below ˜8 K coexistent with a spin-glass state caused by atomic disorder in Ce substituted Ca3Rh4Sn13 . Measurements of specific heat, resistivity, and magnetism reveal the existence of inhomogeneous superconductivity in samples doped with Ce with superconducting critical temperatures Tc higher than those observed in the parent compound. For Ca3Rh4Sn13 , the negative value of the change in resistivity ρ with pressure P , d ρ /d P correlates well with the calculated decrease in the density of states (DOS) at the Fermi energy with P . Based on band-structure calculations performed under pressure, we demonstrate how the change in DOS would affect Tc of Ca3Rh4Sn13 under negative lattice pressure in samples that are strongly defected by quenching.

  13. Logging data representation based on XML


    As an open standard of data representation, XML breathes new energy to the Web application and the network computing. The development, advantage and status of XML and some standards relating to XML are reviewed. In addition, the authors put forward a method representing logging data and using UML language to establish the conceptual and logical model of logging data; using a logging data, explain how to establish the model as well as how to use XML to display and process geology data.

  14. Introducing the representational measurement project in accounting

    Saratiel Weszerai, Musvoto


    This study introduces a representational measurement (a theory that establishes measurement in the social sciences) perspective to the accounting concept of measurement. Accounting studies have long sought to establish foundations (theory) of measurement in accounting without success. This is because the accounting concept of measurement is based on the axioms of quantity which ultimately result in the classical theory of measurement and are not suitable for social science disciplines such as...

  15. Representations and Relations

    Koťátko, Petr


    Roč. 21, č. 3 (2014), s. 282-302. ISSN 1335-0668 Institutional support: RVO:67985955 Keywords : representation * proposition * truth-conditions * belief-ascriptions * reference * externalism * fiction Subject RIV: AA - Philosophy ; Religion

  16. Hyperfinite Representation of Distributions

    J Sousa Pinto; R F Hoskins


    Hyperfinite representation of distributions is studied following the method introduced by Kinoshita [2, 3], although we use a different approach much in the vein of [4]. Products and Fourier transforms of representatives of distributions are also analysed.

  17. Inhibition of the K+ channel K(Ca3.1 reduces TGF-β1-induced premature senescence, myofibroblast phenotype transition and proliferation of mesangial cells.

    Rong-Guo Fu

    Full Text Available OBJECTIVE: K(Ca3.1 channel participates in many important cellular functions. This study planned to investigate the potential involvement of K(Ca3.1 channel in premature senescence, myofibroblast phenotype transition and proliferation of mesangial cells. METHODS & MATERIALS: Rat mesangial cells were cultured together with TGF-β1 (2 ng/ml and TGF-β1 (2 ng/ml + TRAM-34 (16 nM separately for specified times from 0 min to 60 min. The cells without treatment served as controls. The location of K(Ca3.1 channels in mesangial cells was determined with Confocal laser microscope, the cell cycle of mesangial cells was assessed with flow cytometry, the protein and mRNA expression of K(Ca3.1, α-smooth muscle actin (α-SMA and fibroblast-specific protein-1 (FSP-1 were detected with Western blot and RT-PCR. One-way analysis of variance (ANOVA and Student-Newman-Keuls-q test (SNK-q were used to do statistical analysis. Statistical significance was considered at P<0.05. RESULTS: Kca3.1 channels were located in the cell membranes and/or in the cytoplasm of mesangial cells. The percentage of cells in G0-G1 phase and the expression of K(ca3.1, α-SMA and FSP-1 were elevated under the induction of TGF-β1 when compared to the control and decreased under the induction of TGF-β1+TRAM-34 when compared to the TGF-β1 induced (P<0.05 or P<0.01. CONCLUSION: Targeted disruption of K(Ca3.1 inhibits TGF-β1-induced premature aging, myofibroblast-like phenotype transdifferentiation and proliferation of mesangial cells.

  18. Non-aqueous synthesis of water-dispersible Fe3O4-Ca3(PO4)2 core-shell nanoparticles

    The Fe3O4-Ca3(PO4)2 core-shell nanoparticles were prepared by one-pot non-aqueous nanoemulsion with the assistance of a biocompatible triblock copolymer, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO), integrating the magnetic properties of Fe3O4 and the bioactive functions of Ca3(PO4)2 into single entities. The Fe3O4 nanoparticles were pre-formed first by thermal reduction of Fe(acac)3 and then the Ca3(PO4)2 layer was coated by simultaneous deposition of Ca2+ and PO43-. The characterization shows that the combination of the two materials into a core-shell nanostructure retains the magnetic properties and the Ca3(PO4)2 shell forms an hcp phase (a = 7.490 A, c = 9.534 A) on the Fe3O4 surface. The magnetic hysteresis curves of the nanoparticles were further elucidated by the Langevin equation, giving an estimation of the effective magnetic dimension of the nanoparticles and reflecting the enhanced susceptibility response as a result of the surface covering. Fourier transform infrared (FTIR) analysis provides the characteristic vibrations of Ca3(PO4)2 and the presence of the polymer surfactant on the nanoparticle surface. Moreover, the nanoparticles could be directly transferred to water and the aqueous dispersion-collection process of the nanoparticles was demonstrated for application readiness of such core-shell nanostructures in an aqueous medium. Thus, the construction of Fe3O4 and Ca3(PO4)2 in the core-shell nanostructure has conspicuously led to enhanced performance and multi-functionalities, offering various possible applications of the nanoparticles.

  19. Electronic Structure and Thermoelectric Properties of Na and Ni-doped Ca3Co2O6

    MIN Xinmin; YANG Wen


    The electronic structures of Ca3Co2O6, Na and Ni doped models were studied by the quantum chemical software of Cambride Serial Total Energy Package (CASTEP) that is based on density function theory (DFT) and pseudo-potential. The electronic conductivity, seebeck coefficient, thermal conductivity and figure of merit (Z) were computed. The energy band structure reveals the form of the impurity levels due to the substitutional impurity in semiconductors. Na-doped model shows the character of p-type semiconductor, but Ni-doped model is n-type semiconductor. The calculation results show that the electric conductivity of the doped model is higher than that of the non-doped model, while the Seebeck coefficient and thermal conductivity of the doped model are lower than those of the non-doped one. Because of the great increase of the electric conductivity, Z of Na-doped model is enhanced and thermoelectric properties are improved. On the other hand, as the large decline of Seebeck coefficient, Z of Ni-doped model is less than that of the non-doped model.

  20. Intrinsic Josephson properties in (Hg, Re)Ba2Ca3Cu4O10+δ single crystals

    We have investigated the I-V characteristics of intrinsic Josephson junctions (IJJs) in (Hg, Re)Ba2Ca3Cu4O10+δ [Hg(Re)1234]. Two types of inline junctions with different dimensions were fabricated using a focused Ga+ ion beam from Hg(Re)1234 single crystals grown by the flux method. In the I-V curves of the IJJs, multiple-branches with hysteresis structure similar to those of other HTS IJJs were successfully observed above 80 K. The IJJs with dimension of 1.2 x 0.65 μm2 showed almost step by step switching, while the other with larger size showed uniform-stack switching, which indicated that the switching dynamics in the IJJs were affected by the coupling between junctions. The critical current density, Jc, of both IJJs were high ∼320 kA/cm2 at 4.2 K due to its high Tc and relatively low anisotropy parameter γ=(mc*/mab*)1/2∼25

  1. HERC 1 ubiquitin ligase mutation affects neocortical, CA3 hippocampal and spinal cord projection neurons. An ultrastructural study

    Rocío eRuiz


    Full Text Available The spontaneous mutation tambaleante is caused by the Gly483Glu substitution in the highly conserved N terminal RCC1-like domain of the HERC1 protein, which leads to the increase of mutated protein levels responsible for cerebellar Purkinje cell death by autophagy. Until now, Purkinje cells have been the only central nervous neurons reported as being targeted by the mutation, and their degeneration elicits an ataxic syndrome in adult mutant mice. However, the ultrastructural analysis performed here demonstrates that signs of autophagy, such as autophagosomes, lysosomes, and altered mitochondria, are present in neocortical pyramidal, CA3 hippocampal pyramidal, and spinal cord motor neurons. The main difference is that the reduction in the number of neurons affected in the tambaleante mutation in the neocortex, the hippocampus, and the spinal cord is not so evident as the dramatic loss of cerebellar Purkinje cells. Interestingly, signs of autophagy are absent in both interneurons and neuroglia cells. Affected neurons have in common that they are projection neurons which receive strong and varied synaptic inputs, and possess the highest degree of neuronal activity. Therefore, because the integrity of the ubiquitin-proteasome system is essential for protein degradation and, hence, for normal protein turnover, it could be hypothesized that the deleterious effects of the misrouting of these pathways would depend directly on the neuronal activity.

  2. HERC 1 Ubiquitin Ligase Mutation Affects Neocortical, CA3 Hippocampal and Spinal Cord Projection Neurons: An Ultrastructural Study.

    Ruiz, Rocío; Pérez-Villegas, Eva María; Bachiller, Sara; Rosa, José Luis; Armengol, José Angel


    The spontaneous mutation tambaleante is caused by the Gly483Glu substitution in the highly conserved N terminal RCC1-like domain of the HERC1 protein, which leads to the increase of mutated protein levels responsible for cerebellar Purkinje cell death by autophagy. Until now, Purkinje cells have been the only central nervous neurons reported as being targeted by the mutation, and their degeneration elicits an ataxic syndrome in adult mutant mice. However, the ultrastructural analysis performed here demonstrates that signs of autophagy, such as autophagosomes, lysosomes, and altered mitochondria, are present in neocortical pyramidal, CA3 hippocampal pyramidal, and spinal cord motor neurons. The main difference is that the reduction in the number of neurons affected in the tambaleante mutation in the neocortex, the hippocampus, and the spinal cord is not so evident as the dramatic loss of cerebellar Purkinje cells. Interestingly, signs of autophagy are absent in both interneurons and neuroglia cells. Affected neurons have in common that they are projection neurons which receive strong and varied synaptic inputs, and possess the highest degree of neuronal activity. Therefore, because the integrity of the ubiquitin-proteasome system is essential for protein degradation and hence, for normal protein turnover, it could be hypothesized that the deleterious effects of the misrouting of these pathways would depend directly on the neuronal activity. PMID:27147983

  3. Multiple sparse representations classification

    Plenge, Esben; Klein, Stefan; Niessen, Wiro; Meijering, Erik


    textabstractSparse representations classification (SRC) is a powerful technique for pixelwise classification of images and it is increasingly being used for a wide variety of image analysis tasks. The method uses sparse representation and learned redundant dictionaries to classify image pixels. In this empirical study we propose to further leverage the redundancy of the learned dictionaries to achieve a more accurate classifier. In conventional SRC, each image pixel is associated with a small...

  4. Multiple Sparse Representations Classification

    Plenge, Esben; Klein, Stefan S.; Niessen, Wiro J.; Meijering, Erik


    Sparse representations classification (SRC) is a powerful technique for pixelwise classification of images and it is increasingly being used for a wide variety of image analysis tasks. The method uses sparse representation and learned redundant dictionaries to classify image pixels. In this empirical study we propose to further leverage the redundancy of the learned dictionaries to achieve a more accurate classifier. In conventional SRC, each image pixel is associated with a small patch surro...

  5. Embedded data representations

    Willett, W.; Jansen, Yvonne; Dragicevic, P.


    We introduce embedded data representations, the use of visual and physical representations of data that are deeply integrated with the physical spaces, objects, and entities to which the data refers. Technologies like lightweight wireless displays, mixed reality hardware, and autonomous vehicles ......-situated, situated, and embedded data displays, including both visualizations and physicalizations. Based on our observations, we identify a variety of design challenges for embedded data representation, and suggest opportunities for future research and applications.......We introduce embedded data representations, the use of visual and physical representations of data that are deeply integrated with the physical spaces, objects, and entities to which the data refers. Technologies like lightweight wireless displays, mixed reality hardware, and autonomous vehicles...... are making it increasingly easier to display data in-context. While researchers and artists have already begun to create embedded data representations, the benefits, trade-offs, and even the language necessary to describe and compare these approaches remain unexplored. In this paper, we formalize the notion...

  6. Asymptotic representations and Drinfeld rational fractions

    Hernandez, David; Jimbo, Michio


    We introduce and study a category of representations of the Borel algebra, associated with a quantum loop algebra of non-twisted type. We construct fundamental representations for this category as a limit of the Kirillov-Reshetikhin modules over the quantum loop algebra and we establish explicit formulas for their characters. We prove that general simple modules in this category are classified by n-tuples of rational functions in one variable, which are regular and non-zero at the origin but ...

  7. Baclofen and adenosine inhibition of synaptic transmission at CA3-CA1 synapses display differential sensitivity to K+ channel blockade.

    Skov, Jane; Andreasen, Mogens; Hablitz, John J; Nedergaard, Steen


    The metabotropic GABA(B) and adenosine A(1) receptors mediate presynaptic inhibition through regulation of voltage-dependent Ca(2+) channels, whereas K(+) channel regulation is believed to have no role at the CA3-CA1 synapse. We show here that the inhibitory effect of baclofen (20 μM) and adenosine (300 μM) on field EPSPs are differentially sensitive to Cs(+) (3.5 mM) and Ba(2+) (200 μM), but not 4-aminopyridine (100 μM). Barium had no effect on paired-pulse facilitation (PPF) in itself, but gave significant reduction (14 ± 5%) when applied in the presence of baclofen, but not adenosine, suggesting that the effect is presynaptic and selective on the GABA(B) receptor-mediated response. The effect of Ba(2+) on PPF was not mimicked by tertiapin (30 nM), indicating that the underlying mechanism does not involve GIRK channels. Barium did not affect PPF in slices from young rats (P7-P8), suggesting developmental regulation. The above effects of Ba(2+) on adult tissue were reproduced when measuring evoked whole-cell EPSCs from CA1 pyramidal neurons: PPF was reduced by 22 ± 3% in the presence of baclofen and unaltered in adenosine. In contrast, Ba(2+) caused no significant change in frequency or amplitude of miniature EPSCs. The Ba(2+)-induced reduction of PPF was antagonized by LY341495, suggesting metabotropic glutamate receptor involvement. We propose that these novel effects of Ba(2+) and Cs(+) are exerted through blockade of inwardly rectifying K(+) channels in glial cells, which are functionally interacting with the GABA(B) receptor-dependent glutamate release that generates heterosynaptic depression. PMID:21274618

  8. Anomalous behaviour of irreversibility lines in multi-layered superconductor (Cu,C)Ba2Ca3Cu4Oy

    The physical properties of a multi-layered cuprate superconductor (Cu0.6C0.4)Ba2Ca3Cu4Oy are investigated using high-quality samples of varying oxygen content (y ∼ 11.18-10.34). Samples are synthesized using a newly developed method capable of fine control of the starting oxygen and carbon compositions, followed by annealing under N2 flow at various temperatures to modify the oxygen content. While Tc, the lattice constants and T0 change monotonically with y, the irreversibility lines exhibit a discontinuous drop at y ≤ 10.45 amongst a more gradual decrease. This discontinuity has not been observed before for single- or double-layered CuO2 superconductors. This anomaly is attributed to the presence of two different order parameters in this material, arising from the large difference in carrier concentrations of the outer five-coordinated CuO2 planes and inner four-coordinated CuO2 planes. The superconducting gap in the outer planes develops with decreasing y (approaching the optimal doping state), suppressing the decrease in the irreversibility line, while the carrier insensitivity of the inner planes limits the change in Tc. Two different kinks are also observed in the irreversibility lines, tentatively attributed to the development of the superconducting gap and 2D-3D crossover in a vortex system. Control of the doping state of both the inner and outer planes is demonstrated to be important in the design of Jc and Birr, even if the change in Tc is small. This result is also expected to be applicable to other multi-layered superconductors

  9. The Kinetics, Stability and Thermal Contact Resistance of Nickel-Ca3Co4O9 Interfaces Formed by Spark Plasma Sintering

    Holgate, Tim; Wu, NingYu; Søndergaard, M.;


    (Ca3Co4O9) have been formed directly by spark plasma sintering (SPS). An intermediate NiO phase is formed during the SPS processes, which grows during post heating with Co entering from the cobaltate side to form a graded Ni1-xCoxO interfacial layer. The electrical and thermal transport across...

  10. Phosphorylation of the tau protein sequence 199-205 in the hippocampal CA3 region of Syrian hamsters in adulthood and during aging

    Hartig, W; Oklejewicz, M; Strijkstra, AM; Boerema, AS; Stieler, J; Arendt, T


    Paired helical filaments formed by the abnormally phosphorylated microtubule-associated tau are a main sign of Alzheimer's disease and other neurodegenerative disorders. The hippocampal CA3 region, a brain region with a high degree of synaptic plasticity, is known to be strongly involved in tau hype

  11. Excellent stability of plasma-sprayed bioactive Ca3ZrSi2O9 ceramic coating on Ti-6Al-4V

    In this work, novel zirconium incorporated Ca-Si based ceramic powder Ca3ZrSi2O9 was synthesized. The aim of this study was to fabricate Ca3ZrSi2O9 coating onto Ti-6Al-4V substrate using atmospheric plasma-spraying technology and to evaluate its potential applications in the fields of orthopedics and dentistry. The phase composition, surface morphologies of the coating were examined by XRD and SEM, which revealed that the Ca3ZrSi2O9 coating was composed of grains around 100 nm and amorphous phases. The bonding strength between the coating and the substrate was 28 ± 4 MPa, which is higher than that of traditional HA coating. The dissolution rate of the coating was assessed by monitoring the ions release and mass loss after immersion in the Tris-HCl buffer solution. The in vitro bioactivity of the coating was determined by observing the formation of apatite on its surface in simulated body fluids. It was found that the Ca3ZrSi2O9 coating possessed both excellent chemical stability and good apatite-formation ability, suggesting its potential use as bone implants.

  12. Irreversibility line and flux pinning properties in a multilayered cuprate superconductor of Ba2Ca3Cu4O8(O,F)2 (Tc = 105 K)

    Irreversibility line (IL) and flux pinning properties were investigated for a Ba2Ca3Cu4O8(O,F)2 (F-0234) multilayered cuprate superconductor with a Tc of 105 K. The intragrain critical current density (Jc) and irreversibility field (Birr) were determined by using Bean's critical state model for the grain-aligned sample (nominal composition Ba2Ca3Cu4O8.7F1.3). The irreversibility line (IL) of F-0234 is much lower than that of (Cu,C)Ba2Ca3Cu4Oy ((Cu, C)-1234) and HgBa2Ca3Cu4Oy (Hg-1234) in spite of the spacing between the superconducting blocks of F-0234 (7.3 A) being much thinner. The double logarithmic plot of Birr field versus [1-(T/Tc) ] analysis hints that the flux line melting model has been adopted. An anisotropy factor of 65 was calculated from a 3D to 2D crossover field of about 0.95 T. Due to the high anisotropy of this system, a low IL has resulted. The flux pinning force density Fp ( ∼JcB) exhibits scaling behaviour when the magnetic field B is normalized by the Birr field. Analysis of the normalized pinning force reveals that a surface pinning mechanism is dominant and the reduced magnetic field bmax = 0.2 agrees with surface pinning mechanism with closely spaced pins

  13. Unitary Representations of Gauge Groups

    Huerfano, Ruth Stella

    I generalize to the case of gauge groups over non-trivial principal bundles representations that I. M. Gelfand, M. I. Graev and A. M. Versik constructed for current groups. The gauge group of the principal G-bundle P over M, (G a Lie group with an euclidean structure, M a compact, connected and oriented manifold), as the smooth sections of the associated group bundle is presented and studied in chapter I. Chapter II describes the symmetric algebra associated to a Hilbert space, its Hilbert structure, a convenient exponential and a total set that later play a key role in the construction of the representation. Chapter III is concerned with the calculus needed to make the space of Lie algebra valued 1-forms a Gaussian L^2-space. This is accomplished by studying general projective systems of finitely measurable spaces and the corresponding systems of sigma -additive measures, all of these leading to the description of a promeasure, a concept modeled after Bourbaki and classical measure theory. In the case of a locally convex vector space E, the corresponding Fourier transform, family of characters and the existence of a promeasure for every quadratic form on E^' are established, so the Gaussian L^2-space associated to a real Hilbert space is constructed. Chapter III finishes by exhibiting the explicit Hilbert space isomorphism between the Gaussian L ^2-space associated to a real Hilbert space and the complexification of its symmetric algebra. In chapter IV taking as a Hilbert space H the L^2-space of the Lie algebra valued 1-forms on P, the gauge group acts on the motion group of H defining in an straight forward fashion the representation desired.

  14. Representation Discovery using Harmonic Analysis

    Mahadevan, Sridhar


    Representations are at the heart of artificial intelligence (AI). This book is devoted to the problem of representation discovery: how can an intelligent system construct representations from its experience? Representation discovery re-parameterizes the state space - prior to the application of information retrieval, machine learning, or optimization techniques - facilitating later inference processes by constructing new task-specific bases adapted to the state space geometry. This book presents a general approach to representation discovery using the framework of harmonic analysis, in particu

  15. Understanding representations in design

    Bødker, Susanne


    Representing computer applications and their use is an important aspect of design. In various ways, designers need to externalize design proposals and present them to other designers, users, or managers. This article deals with understanding design representations and the work they do in design....... The article is based on a series of theoretical concepts coming out of studies of scientific and other work practices and on practical experiences from design of computer applications. The article presents alternatives to the ideas that design representations are mappings of present or future work...... regarding use and design. The article proposes that abstraction, elevating the representation from the situation, is not the only way to do this, and it proposes alternatives....

  16. Memetics of representation

    Roberto De Rubertis


    Full Text Available This article will discuss about the physiological genesis of representation and then it will illustrate the developments, especially in evolutionary perspective, and it will show how these are mainly a result of accidental circumstances, rather than of deliberate intention of improvement. In particular, it will be argue that the representation has behaved like a meme that has arrived to its own progressive evolution coming into symbiosis with the different cultures in which it has spread, and using in this activity human work “unconsciously”. Finally it will be shown how in this action the geometry is an element key, linked to representation both to construct images using graphics operations and to erect buildings using concrete operations.

  17. Towards Multimodal Content Representation

    Bunt, Harry


    Multimodal interfaces, combining the use of speech, graphics, gestures, and facial expressions in input and output, promise to provide new possibilities to deal with information in more effective and efficient ways, supporting for instance: - the understanding of possibly imprecise, partial or ambiguous multimodal input; - the generation of coordinated, cohesive, and coherent multimodal presentations; - the management of multimodal interaction (e.g., task completion, adapting the interface, error prevention) by representing and exploiting models of the user, the domain, the task, the interactive context, and the media (e.g. text, audio, video). The present document is intended to support the discussion on multimodal content representation, its possible objectives and basic constraints, and how the definition of a generic representation framework for multimodal content representation may be approached. It takes into account the results of the Dagstuhl workshop, in particular those of the informal working group...

  18. Prenatal nicotine and maternal deprivation stress de-regulate the development of CA1, CA3, and dentate gyrus neurons in hippocampus of infant rats.

    Hong Wang

    Full Text Available Adverse experiences by the developing fetus and in early childhood are associated with profound effects on learning, emotional behavior, and cognition as a whole. In this study we investigated the effects of prenatal nicotine exposure (NIC, postnatal maternal deprivation (MD or the combination of the two (NIC+MD to determine if hippocampal neuron development is modulated by exposure to drugs of abuse and/or stress. Growth of rat offspring exposed to MD alone or NIC+MD was repressed until after weaning. In CA1 but not CA3 of postnatal day 14 (P14 pups, MD increased pyramidal neurons, however, in dentate gyrus (DG, decreased granule neurons. NIC had no effect on neuron number in CA1, CA3 or DG. Unexpectedly, NIC plus MD combined caused a synergistic increase in the number of CA1 or CA3 neurons. Neuron density in CA regions was unaffected by treatment, but in the DG, granule neurons had a looser packing density after NIC, MD or NIC+MD exposure. When septotemporal axes were analyzed, the synergism of stress and drug exposure in CA1 and CA3 was associated with rostral, whereas MD effects were predominantly associated with caudal neurons. TUNEL labeling suggests no active apoptosis at P14, and doublecortin positive neurons and mossy fibers were diminished in NIC+MD relative to controls. The laterality of the effect of nicotine and/or maternal deprivation in right versus left hippocampus was also analyzed and found to be insiginificant. We report for the first time that early life stressors such as postnatal MD and prenatal NIC exposure, when combined, may exhibit synergistic consequences for CA1 and CA3 pyramidal neuron development, and a potential antagonistic influence on developing DG neurons. These results suggest that early stressors may modulate neurogenesis, apoptosis, or maturation of glutamatergic neurons in the hippocampus in a region-specific manner during critical periods of neurodevelopment.

  19. Changes in synaptic plasticity and expression of glutamate receptor subunits in the CA1 and CA3 areas of the hippocampus after transient global ischemia.

    Han, Xin-Jia; Shi, Zhong-Shan; Xia, Luo-Xing; Zhu, Li-Hui; Zeng, Ling; Nie, Jun-Hua; Xu, Zao-Cheng; Ruan, Yi-Wen


    Excess glutamate release from the presynaptic membrane has been thought to be the major cause of ischemic neuronal death. Although both CA1 and CA3 pyramidal neurons receive presynaptic glutamate input, transient cerebral ischemia induces CA1 neurons to die while CA3 neurons remain relatively intact. This suggests that changes in the properties of pyramidal cells may be the main cause related to ischemic neuronal death. Our previous studies have shown that the densities of dendritic spines and asymmetric synapses in the CA1 area are increased at 12h and 24h after ischemia. In the present study, we investigated changes in synaptic structures in the CA3 area and compared the expression of glutamate receptors in the CA1 and CA3 hippocampal regions of rats after ischemia. Our results demonstrated that the NR2B/NR2A ratio became larger after ischemia although the expression of both the NR2B subunit (activation of apoptotic pathway) and NR2A subunit (activation of survival pathway) decreased in the CA1 area from 6h to 48h after reperfusion. Furthermore, expression of the GluR2 subunit (calcium impermeable) of the AMPA receptor class significantly decreased while the GluR1 subunit (calcium permeable) remained unchanged at the same examined reperfusion times, which subsequently caused an increase in the GluR1/GluR2 ratio. Despite these notable differences in subunit expression, there were no obvious changes in the density of synapses or expression of NMDAR and AMPAR subunits in the CA3 area after ischemia. These results suggest that delayed CA1 neuronal death may be related to the dramatic fluctuation in the synaptic structure and relative upregulation of NR2B and GluR1 subunits induced by transient global ischemia. PMID:27090818

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

    Oscar eHerreras


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

  1. Representations used by mathematics student teachers in mathematical modeling process

    Aytuğ Özaltun


    Full Text Available The purpose of this study is to determine representations used by mathematics student teachers in steps of mathematical modeling process based on their solutions of problems formed in the context of different classification of modeling. The study was conducted with fifteen secondary mathematics student teachers given a Mathematical Modeling course. The participants were separated into five collaboration groups of three students. Data were collected with the detailed written papers given by the groups for the problems and GeoGebra solution files. The groups benefited from verbal, algebraic, figural, tabular and dynamic representations while they were solving the problems. Considering all steps of the process, groups at most used verbal and algebraic representations. While they used only verbal representation in analyzing the problem, they benefited from at most verbal representation and then figural representation in establishing the systematic structure. The most used is algebraic and then verbal representations in the steps of mathematization, meta-mathematization, and mathematical analysis. In the steps of interpretation/evaluation and the model verification, the groups mainly benefited from verbal and then algebraic representations. Further researches towards why representations are preferred in the specific steps of the mathematical modeling process are suggested.Key Words: Mathematical modeling, modeling problems, mathematics student teachers, representations.

  2. Additive and polynomial representations

    Krantz, David H; Suppes, Patrick


    Additive and Polynomial Representations deals with major representation theorems in which the qualitative structure is reflected as some polynomial function of one or more numerical functions defined on the basic entities. Examples are additive expressions of a single measure (such as the probability of disjoint events being the sum of their probabilities), and additive expressions of two measures (such as the logarithm of momentum being the sum of log mass and log velocity terms). The book describes the three basic procedures of fundamental measurement as the mathematical pivot, as the utiliz

  3. Scientific Representation and Realism

    Michel Ghins


    Full Text Available After a brief presentation of what I take to be the representational démarche in science, I stress the fundamental role of true judgements in model construction. The success and correctness of a representation rests on the truth of judgements which attribute properties to real targeted entities, called “ontic judgements”. I then present what van Fraassen calls “the Loss of Reality objection”. After criticizing his dissolution of the objection, I offer an alternative way of answering the Loss of Reality objection by showing that the contact of our models with reality is grounded on the truth of ontic judgements. I conclude by examining.

  4. On the equivalence of GPD representations

    Müller, Dieter


    Phenomenological representations of generalized parton distributions (GPDs) implementing the non-trivial field theoretical requirements are employed in the present day strategies for extracting of hadron structure information encoded in GPDs from the observables of hard exclusive reactions. Showing out the equivalence of various GPD representations can help to get more insight into GPD properties and allow to build up flexible GPD models capable of satisfactory description of the whole set of available experimental data. We review the mathematical aspects of establishing equivalence between the the double partial wave expansion of GPDs in the conformal partial waves and in the $t$-channel ${\\rm SO}(3)$ partial waves and the double distribution representation of GPDs.

  5. Social representations of climate change

    Each year since 2000, the French 'ADEME' (Agency for Environment and Energy Management) conducts a survey on the social representations of greenhouse effect and global warming. This survey is administered by telephone to a representative sample of the French population. The information gathered in the database can answer a series of basic questions concerning public perception in this area. What do the concepts of 'greenhouse effect' and 'global warming' mean for the public? To what extent do people think there is a consensus among scientists to explain these phenomena? Is responsibility for human action clearly established? What kind of solutions, based on public regulation or private initiative can help to remedy this situation? Finally, what were the major changes in public opinion over this 12 years period? (author)

  6. Proportional Representation with Uncertainty

    Francesco De Sinopoli; Giovanna Iannantuoni; Elena Manzoni; Carlos Pimienta


    We introduce a model with strategic voting in a parliamentary election with proportional representation and uncertainty about voters’ preferences. In any equilibrium of the model, most voters only vote for those parties whose positions are extreme. In the resulting parliament, a consensus government forms and the policy maximizing the sum of utilities of the members of the government is implemented.

  7. Social representations about cancer

    Andreja Cirila Škufca


    Full Text Available In this article we are presenting the results of the comparison study on social representations and causal attributions about cancer. We compared a breast cancer survivors group and control group without own experience of cancer of their own. Although social representations about cancer differ in each group, they are closely related to the concept of suffering, dying and death. We found differences in causal attribution of cancer. In both groups we found a category of risky behavior, which attributes a responsibility for a disease to an individual. Besides these factors we found predominate stress and psychological influences in cancer survivors group. On the other hand control group indicated factors outside the ones control e.g. heredity and environmental factors. Representations about a disease inside person's social space are important in co-shaping the individual process of coping with own disease. Since these representations are not always coherent with the knowledge of modern medicine their knowledge and appreciation in the course of treatment is of great value. We find the findingss of applied social psychology important as starting points in the therapeutic work with patients.

  8. Moment graphs and representations

    Jantzen, Jens Carsten


    Moment graphs and sheaves on moment graphs are basically combinatorial objects that have be used to describe equivariant intersectiion cohomology. In these lectures we are going to show that they can be used to provide a direct link from this cohomology to the representation theory of simple Lie...

  9. Qualitative aspects of representational competence among college chemistry students: Multiple representations and their role in the understanding of ideal gases

    Madden, Sean Patrick

    This study examined the role of multiple representations of chemical phenomena, specifically, the temperature-pressure relationship of ideal gases, in the problem solving strategies of college chemistry students. Volunteers included students enrolled in a first semester general chemistry course at a western university. Two additional volunteers from the same university were asked to participate and serve as models of greater sophistication. One was a senior chemistry major; another was a junior science writing major. Volunteers completed an initial screening task involving multiple representations of concentration and dilution concepts. Based on the results of this screening instrument a smaller set of subjects were asked to complete a think aloud session involving multiple representations of the temperature-pressure relationship. Data consisted of the written work of the volunteers and transcripts from videotaped think aloud sessions. The data were evaluated by the researcher and two other graduate students in chemical education using a coding scheme (Kozma, Schank, Coppola, Michalchik, and Allen. 2000). This coding scheme was designed to identify essential features of representational competence and differences in uses of multiple representations. The results indicate that students tend to have a strong preference for one type of representation. Students scoring low on representational competence, as measured by the rubric, ignored important features of some representations or acknowledged them only superficially. Students scoring higher on representational competence made meaningful connections among representations. The more advanced students, those who rated highly on representational competence, tended to use their preferred representation in a heuristic manner to establish meaning for other representations. The more advanced students also reflected upon the problem at greater length before beginning work. Molecular level sketches seemed to be the most

  10. Superconductivity and thermoelectric power in Tl2Ca2Ba2Cu3O10 and TlCa3BaCu3O9

    The authors report the synthesis and superconducting temperature of the high-Tc compounds Tl2Ca2Ba2Cu3O10 and TlCa3BaCu3O9. The transition to the superconducting state was measured by the magnetic susceptibility changes and by the temperature dependence of the electrical a.c and d.c. resistivity and by thermoelectric power measurements. For Tl2Ca2Cu3O10 a superconducting transition with zero resistance at 114.5Κ have been observed. Higher Tc with zero resistance at 122Κ have been found in TlCa3BaCu3O9

  11. Synaptic remodeling in the dentate gyrus, CA3, CA1, subiculum, and entorhinal cortex of mice: effects of deprived rearing and voluntary running.

    Schaefers, Andrea T U; Grafen, Keren; Teuchert-Noodt, Gertraud; Winter, York


    Hippocampal cell proliferation is strongly increased and synaptic turnover decreased after rearing under social and physical deprivation in gerbils (Meriones unguiculatus). We examined if a similar epigenetic effect of rearing environment on adult neuroplastic responses can be found in mice (Mus musculus). We examined synaptic turnover rates in the dentate gyrus, CA3, CA1, subiculum, and entorhinal cortex. No direct effects of deprived rearing on rates of synaptic turnover were found in any of the studied regions. However, adult wheel running had the effect of leveling layer-specific differences in synaptic remodeling in the dentate gyrus, CA3, and CA1, but not in the entorhinal cortex and subiculum of animals of both rearing treatments. Epigenetic effects during juvenile development affected adult neural plasticity in mice, but seemed to be less pronounced than in gerbils. PMID:20508828

  12. Synaptic Remodeling in the Dentate Gyrus, CA3, CA1, Subiculum, and Entorhinal Cortex of Mice: Effects of Deprived Rearing and Voluntary Running

    Andrea T. U. Schaefers


    Full Text Available Hippocampal cell proliferation is strongly increased and synaptic turnover decreased after rearing under social and physical deprivation in gerbils (Meriones unguiculatus. We examined if a similar epigenetic effect of rearing environment on adult neuroplastic responses can be found in mice (Mus musculus. We examined synaptic turnover rates in the dentate gyrus, CA3, CA1, subiculum, and entorhinal cortex. No direct effects of deprived rearing on rates of synaptic turnover were found in any of the studied regions. However, adult wheel running had the effect of leveling layer-specific differences in synaptic remodeling in the dentate gyrus, CA3, and CA1, but not in the entorhinal cortex and subiculum of animals of both rearing treatments. Epigenetic effects during juvenile development affected adult neural plasticity in mice, but seemed to be less pronounced than in gerbils.

  13. Realizations of the Canonical Representation

    M K Vemuri


    A characterisation of the maximal abelian subalgebras of the bounded operators on Hilbert space that are normalised by the canonical representation of the Heisenberg group is given. This is used to classify the perfect realizations of the canonical representation.

  14. A Parametric Representation of Additive Value Functions

    Thomas W. Keelin


    This paper introduces a new parameter for measuring deterministic preference tradeoffs between pairs of attributes. In terms of this parameter, necessary and sufficient conditions for a value function to be additive are established. When additivity conditions are satisfied, a set of these parameters is shown to characterize the value function uniquely up to a set of scaling constants. Implications for assessment, for transforming a nonadditive representation into an additive one, and for mult...

  15. Comparison of the effects of Na2CO3, Ca3(PO4)2, and NiO catalysts on the thermochemical liquefaction of microalga Spirulina platensis

    Highlights: ► We evaluated the effect of catalysts on TCL of microalgae for biofuel production. ► Addition of catalysts affected the product yield and energy consumption ratio in TCL process. ► Addition of Na2CO3 increased the biocrude oil yield, whereas NiO and Ca3(PO4)2 increased the gaseous yields. -- Abstract: This study investigated the effect of three types of catalysts on the yield of biocrude oil from thermochemical liquefaction (TCL) of the microalga, Spirulina platensis. TCL experiments were performed in a 1.8 L batch reactor using an alkali metal catalyst (Na2CO3), an alkaline earth metal (Ca3(PO4)2), and a transition metal oxide (NiO) and compared with non-catalytic TCL results. Na2CO3 was found to increase biocrude oil yield resulting in 51.6% biocrude oil, which was ∼29.2% higher than under non-catalytic conditions and ∼71% and ∼50% higher than when using NiO and Ca3(PO4)2 catalysts, respectively. Presence of NiO and Ca3(PO4)2 increased yields of gaseous products. GC–MS analysis indicated critical differences in chemical composition of the biocrude oil obtained under different catalyst conditions. Biocrude oil from the catalyzed runs had greater abundance of monoaromatic compounds and lesser polyaromatic and aliphatic compounds than that of non-catalyzed reactions. TCL using Na2CO3 reported the lowest energy consumption ratio and recovered highest energy in the form of biocrude oil among all treatments. Algal biocrude oil had an energy density of 34–39 MJ kg−1 compared to 43 MJ kg−1 for petroleum crude, but had higher oxygen and nitrogen levels. In all cases, the solids conversion was more than 94%. Analysis of solids revealed that 40–60% of the initial catalysts were retained in the solid char.

  16. High-energy passively Q-switched laser operation of Yb:Ca3La2(BO3)4 disordered crystal.

    Wang, Lisha; Han, Wenjuan; Pan, Zhongben; Xu, Honghao; Chen, Xiaowen; Liu, Junhai; Yu, Haohai; Zhang, Huaijin


    Efficient high-energy passively Q-switched laser operation was demonstrated with Yb:Ca3La2(BO3)4 disordered crystal, producing an average output power of 3.0 W at 1018.7 nm, at a pulse repetition frequency of 5.0 kHz; the resulting pulse energy, duration, and peak power were 600 μJ, 5.3 ns, and 113.2 kW, respectively. PMID:27140354

  17. M2 muscarinic acetylcholine receptors regulate long-term potentiation at hippocampal CA3 pyramidal cell synapses in an input-specific fashion

    Zheng, Fang; Wess, Jürgen; Alzheimer, Christian


    Muscarinic receptors have long been known as crucial players in hippocampus-dependent learning and memory, but our understanding of the cellular underpinnings and the receptor subtypes involved lags well behind. This holds in particular for the hippocampal CA3 region, where the mechanisms of synaptic plasticity depend on the type of afferent input. Williams and Johnston (Williams S, Johnston D. Science 242: 84–87, 1988; Williams S, Johnston D. J Neurophysiol 64: 1089–1097, 1990) demonstrated ...

  18. Step change in equilibrium magnetization across the second magnetization peak and the peak effect region of a weakly pinned low Tc superconductor, Ca3Rh4Sn13

    Isothermal magnetization studies in a low Tc type II superconductor, Ca3Rh4Sn13 (Tc≈8.37K), show abrupt step changes in the equilibrium magnetization lines across the second magnetization peak and the peak effect regions suggesting that both of these phenomena are first order phase transitions. We also observed two jumps in the equilibrium magnetization at two different temperature (or field) domains for a constant field (or temperature) in this low Tc superconductor

  19. K+ at an deficient Ca2+ point position in Ca3(VO4)2: on KCa10V7O28

    Single crystals of KCa10V7O28 have been prepared by crystallization from flux. The yellow-green crystals show rhombohedral symmetry (trigonal space group C63v-R3c, a = 10.830(1), c = 37.860(1) A, Z = 6). The differences of the crystal chemistry are discussed with respect to the isotypic compound Ca3(VO4)2. K+ replaces exclusively Ca2+ ions at one deficient point position. (orig.)

  20. Processing and in vitro bioactivity of a β-Ca3(PO4)2-CaMg(SiO3)2 ceramic with the eutectic composition

    In this study, a dense bioactive ceramic, with nominal composition (wt.%) 40 Ca3(PO4)2-60 CaMg(SiO3)2, was prepared by solid state sintering of homogeneous compacted mixtures of fine synthetic Ca3(PO4)2 and CaMg(SiO3)2 powders. The results obtained by X-ray diffraction and field emission scanning electron microscopy with microanalysis indicate that the ceramic composite showed a fine grained and homogeneous microstructure consisting of diopside (CaMg(SiO3)2) and whitlockite (β-Ca3(PO4)2ss) grains with very small amounts of apatite. The flexural strength and elastic modulus values of the composite are similar to those of cortical human bone. Bioactivity was experimentally evaluated by examining in vitro apatite formation in simulated body fluid (SBF). In addition, a simulation of the dissolution properties of the different phases present in the material in SBF was carried out by thermodynamic calculations, with the purpose of understanding the in vitro results obtained. The experimental results demonstrated that, during soaking in SBF, the grains of whitlockite dissolved preferentially than those of diopside, leaving a porous surface layer rich in diopside. Subsequently, partial dissolution of the remaining diopside occurred and the porous surface of the ceramic became coated by a bone-like apatite layer after 7 days in SBF. This bio ceramic containing β-Ca3(PO4)2 and CaMg(SiO3)2 is expected to be useful to fabricate scaffolds for bone repair. (Author)

  1. Disinhibition of hippocampal CA3 neurons induced by suppression of an adenosine A1 receptor-mediated inhibitory tonus: Pre- and postsynaptic components

    Alzheimer, Christian; Sutor, Bernd; Ten Bruggencate, Gerrit


    Intracellular recordings were performed on hippocampal CA3 neuronsin vitro to investigate the inhibitory tonus generated by endogenously produced adenosine in this brain region. Bath application of the highly selective adenosine A1 receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine at concentrations up to 100 nM induced both spontaneous and stimulus-evoked epileptiform burst discharges. Once induced, the 1,3-dipropyl-8-cyclopentylxanthine-evoked epileptiform activity was apparently irreve...

  2. Hypersensitivity of the hippocampal CA3 region to stress-induced neurodegeneration and amyloidogenesis in a rat model of surgical menopause

    Zhang, Quan-guang; Wang, Rui-Min; Scott, Erin; Han, Dong; Dong, Yan; Tu, Jing-yi; Yang, Fang; Reddy Sareddy, Gangadhara; Ratna K. Vadlamudi; Brann, Darrell W.


    Females who enter menopause prematurely via bilateral ovariectomy (surgical menopause) have a significantly increased risk for cognitive decline and dementia. To help elucidate the mechanisms underlying this phenomenon, we used an animal model of surgical menopause, long-term (10-week) bilateral ovariectomy in female rats. Herein, we demonstrate that long-term oestrogen deprivation dramatically increases sensitivity of the normally resistant hippocampal CA3 region to ischaemic stress, an effe...

  3. Constructing visual representations

    Huron, Samuel; Jansen, Yvonne; Carpendale, Sheelagh


    tangible building blocks. We learned that all participants, most of whom had little experience in visualization authoring, were readily able to create and talk about their own visualizations. Based on our observations, we discuss participants’ actions during the development of their visual representations......The accessibility of infovis authoring tools to a wide audience has been identified as a major research challenge. A key task in the authoring process is the development of visual mappings. While the infovis community has long been deeply interested in finding effective visual mappings......, comparatively little attention has been placed on how people construct visual mappings. In this paper, we present the results of a study designed to shed light on how people transform data into visual representations. We asked people to create, update and explain their own information visualizations using only...

  4. Harmonic Analysis and Group Representation

    Figa-Talamanca, Alessandro


    This title includes: Lectures - A. Auslander, R. Tolimeri - Nilpotent groups and abelian varieties, M Cowling - Unitary and uniformly bounded representations of some simple Lie groups, M. Duflo - Construction de representations unitaires d'un groupe de Lie, R. Howe - On a notion of rank for unitary representations of the classical groups, V.S. Varadarajan - Eigenfunction expansions of semisimple Lie groups, and R. Zimmer - Ergodic theory, group representations and rigidity; and, Seminars - A. Koranyi - Some applications of Gelfand pairs in classical analysis.

  5. Multiple Sparse Representations Classification.

    Plenge, Esben; Klein, Stefan; Klein, Stefan S; Niessen, Wiro J; Meijering, Erik


    Sparse representations classification (SRC) is a powerful technique for pixelwise classification of images and it is increasingly being used for a wide variety of image analysis tasks. The method uses sparse representation and learned redundant dictionaries to classify image pixels. In this empirical study we propose to further leverage the redundancy of the learned dictionaries to achieve a more accurate classifier. In conventional SRC, each image pixel is associated with a small patch surrounding it. Using these patches, a dictionary is trained for each class in a supervised fashion. Commonly, redundant/overcomplete dictionaries are trained and image patches are sparsely represented by a linear combination of only a few of the dictionary elements. Given a set of trained dictionaries, a new patch is sparse coded using each of them, and subsequently assigned to the class whose dictionary yields the minimum residual energy. We propose a generalization of this scheme. The method, which we call multiple sparse representations classification (mSRC), is based on the observation that an overcomplete, class specific dictionary is capable of generating multiple accurate and independent estimates of a patch belonging to the class. So instead of finding a single sparse representation of a patch for each dictionary, we find multiple, and the corresponding residual energies provides an enhanced statistic which is used to improve classification. We demonstrate the efficacy of mSRC for three example applications: pixelwise classification of texture images, lumen segmentation in carotid artery magnetic resonance imaging (MRI), and bifurcation point detection in carotid artery MRI. We compare our method with conventional SRC, K-nearest neighbor, and support vector machine classifiers. The results show that mSRC outperforms SRC and the other reference methods. In addition, we present an extensive evaluation of the effect of the main mSRC parameters: patch size, dictionary size, and

  6. Computing modular Galois representations

    Mascot, Nicolas


    We compute modular Galois representations associated with a newform $f$, and study the related problem of computing the coefficients of $f$ modulo a small prime $\\ell$. To this end, we design a practical variant of the complex approximations method presented in the book edited by B. Edixhoven and J.-M. Couveignes. Its efficiency stems from several new ingredients. For instance, we use fast exponentiation in the modular jacobian instead of analytic continuation, which greatly reduces the need ...

  7. Computing modular Galois representations

    Nicolas Mascot


    We compute modular Galois representations associated with a newform $f$, and study the related problem of computing the coefficients of $f$ modulo a small prime $\\ell$. To this end, we design a practical variant of the complex approximations method presented in the book edited by B. Edixhoven and J.-M. Couveignes. Its efficiency stems from several new ingredients. For instance, we use fast exponentiation in the modular jacobian instead of analytic continuation, which greatly reduces the need ...

  8. Repositories with Direct Representation

    Allen, Robert Burnell


    A new generation of digital repositories could be based on direct representation of the contents with rich semantics and models rather than be collections of documents. The contents of such repositories would be highly structured which should help users to focus on meaningful relationships of the contents. These repositories would implement earlier proposals for model-oriented information organization by extending current work on ontologies to cover state changes, instances, and scenarios. Th...

  9. Numerical representations in primates.

    Hauser, M D; MacNeilage, P; M. Ware


    Research has demonstrated that human infants and nonhuman primates have a rudimentary numerical system that enables them to count objects or events. More recently, however, studies using a preferential looking paradigm have suggested that preverbal human infants are capable of simple arithmetical operations, such as adding and subtracting a small number of visually presented objects. These findings implicate a relatively sophisticated representational system in the absence of language. To exp...

  10. Representations in Undergraduate Physics

    Airey, John


    Representations in undergraduate physics Problem solving is one of the most important parts of undergraduate physics education, yet a huge body of international research has clearly shown that simply being able to solve a set of physics problems correctly is not a good indicator of students having attained appropriate physics understanding. Grounded in a comparison of the way experts and novices solve problems, the research focus has gradually shifted towards the importance of representationa...

  11. Islam and Media Representations

    Mohamed Bensalah


    For the author of this article, the media’s treatment of Islam has raised numerous polymorphous questions and debates. Reactivated by the great scares of current events, the issue, though an ancient one, calls many things into question. By way of introduction, the author tries to analyse the complex processes of elaboration and perception of the representations that have prevailed during the past century. In referring to the semantic decoding of the abundant colonial literature and iconograph...

  12. Semantic Representation of Synaesthesia

    Meier, Beat


    Synaesthesia has multifaceted consequences for both subjective experience and cognitive performance. Here, I broach the issue of how synaesthesia is represented in semantic memory. I hypothesize that, for example, in grapheme colour synaesthesia, colour is represented as an additional feature in the semantic network that enables the formation of associations that are not present in non-synaesthetes. Thus, synaesthesia provokes richer memory representations which enable learning opportunities ...

  13. Effects of conducting oxide barrier layers on the stability of Crofer® 22 APU/Ca3Co4O9 interfaces

    Holgate, Tim C.; Han, Li; Wu, NingYu;


    available high-chrome iron alloy (i.e., Crofer® 22 APU) serving as the interconnect metal was spray coated with LaNi0.6Fe0.4O3 (LNFO) or (Mn,Co)3O4 spinel and then interfaced with a p-type thermoelectric material—calcium cobaltate (Ca3Co4O9)—using spark plasma sintering. The interfaces have been...... characterized in terms of their thermal and electronic transport properties and chemical stability. With long-term exposure of the interfaced samples to 800 °C in air, the cobalt–manganese spinel acted as a diffusion barrier between the Ca3Co4O9 and the Crofer® 22 APU alloy resulting in improved interfacial...... stability compared to that of samples containing LNFO as a barrier layer, and especially those without any barrier. The initial area specific interfacial resistance of the Ca3Co4O9/(Mn,Co)3O4/Crofer® 22 APU interface at 800 °C was found to be ∼1 mΩ·cm2....

  14. Synthesis and luminescence properties of a broad-band red phosphor Ca3Si2O7:Eu2+ for warm white light-emitting diodes

    Single-phase broad-band red-emitting Ca3Si2O7:Eu2+ phosphors, with photoluminescence features that qualify them as candidates for white light-emitting diodes applications, were successfully synthesized via a modified solid-state reaction method that employed H3BO3 as a flux. The phosphors produced have an intense broad red emission band, with a peak at 603 nm, a full width at half maximum of 110 nm, and color coordinates of (0.550, 0.438). Concentration quenching occurred at 0.01 mol Eu2+. The discussion of the results shows that Eu2+ ions should be accommodated at the Ca-sites of the lattice, dipole-dipole interactions should predominantly govern the energy transfer mechanism among them, and the critical distance between them is ∼31 A. - Highlights: → Pure Ca3Si2O7:Eu2+ phosphor was successfully synthesized by adding H3BO3 . → Effects of H3BO3 on phase formation and emission intensity were presented. → Luminescence properties in conjunction with Ca3Si2O7 structure were studied. → Energy transfer mechanism of Eu2+ and its critical distance were proposed.

  15. The GLP-1 Receptor Agonist Exendin-4 and Diazepam Differentially Regulate GABAA Receptor-Mediated Tonic Currents in Rat Hippocampal CA3 Pyramidal Neurons.

    Sergiy V Korol

    Full Text Available Glucagon-like peptide-1 (GLP-1 is a metabolic hormone that is secreted in a glucose-dependent manner and enhances insulin secretion. GLP-1 receptors are also found in the brain where their signalling affects neuronal activity. We have previously shown that the GLP-1 receptor agonists, GLP-1 and exendin-4 enhanced GABA-activated synaptic and tonic currents in rat hippocampal CA3 pyramidal neurons. The hippocampus is the centre for memory and learning and is important for cognition. Here we examined if exendin-4 similarly enhanced the GABA-activated currents in the presence of the benzodiazepine diazepam. In whole-cell recordings in rat brain slices, diazepam (1 μM, an allosteric positive modulator of GABAA receptors, alone enhanced the spontaneous inhibitory postsynaptic current (sIPSC amplitude and frequency by a factor of 1.3 and 1.6, respectively, and doubled the tonic GABAA current normally recorded in the CA3 pyramidal cells. Importantly, in the presence of exendin-4 (10 nM plus diazepam (1 μM, only the tonic but not the sIPSC currents transiently increased as compared to currents recorded in the presence of diazepam alone. The results suggest that exendin-4 potentiates a subpopulation of extrasynaptic GABAA receptors in the CA3 pyramidal neurons.

  16. Photoluminescence investigation of rare-earth activated GdCa3(GaO)3(BO3)4 phosphors under UV excitation

    A borate compound was adopted as a new host material of Eu3+ and Tb3+ activators to fabricate efficient luminescence materials. The phosphor compositions, Gd1-xEuxCa3(GaO)3(BO3)4 and Gd1-xTbxCa3(GaO)3(BO3)4, were synthesized by conventional solid-state reactions. The crystalline phases of the resulting powders were identified using an X-ray diffraction system. Their photoluminescence properties were investigated under long-wavelength UV excitation. The Eu3+-doped and Tb3+-doped GdCa3(GaO)3(BO3)4 phosphors efficiently emitted red and green light, respectively. The temperature dependency of emission intensity was measured in a range from room temperature to 150 deg. C. The emission intensities of the red and green phosphors at 150 deg. C are 87% and 91% of those at room temperature, respectively. In addition, the decay times of both the red and green phosphors are shorter than 3 ms

  17. The functional nature of synaptic circuitry is altered in area CA3 of the hippocampus in a mouse model of Down's syndrome

    Hanson, Jesse E; Blank, Martina; Valenzuela, Ricardo A; Garner, Craig C; Madison, Daniel V


    Down's syndrome (DS) is the most common cause of mental retardation, and memory impairments are more severe in DS than in most if not all other causes of mental retardation. The Ts65Dn mouse, a genetic model of DS, exhibits phenotypes of DS, including memory impairments indicative of hippocampal dysfunction. We examined functional synaptic connectivity in area CA3 of the hippocampus of Ts65Dn mice using organotypic slice cultures as a model. We found reductions in multiple measures of synaptic function in both excitatory and inhibitory inputs to pyramidal neurons in CA3 of the Ts65Dn hippocampus. However, associational synaptic connections between pyramidal neurons were more abundant and more likely to be active rather than silent in the Ts65Dn hippocampus. Synaptic potentiation was normal in these associational connections. Decreased overall functional synaptic input onto pyramidal neurons expressed along with the specific hyperconnectivity of associational connections between pyramidal neurons will result in predictable alterations of CA3 network function, which may contribute to the memory impairments seen in DS. PMID:17158177

  18. [Time perceptions and representations].

    Tordjman, S


    Representations of time and time measurements depend on subjective constructs that vary according to changes in our concepts, beliefs, societal needs and technical advances. Similarly, the past, the future and the present are subjective representations that depend on each individual's psychic time and biological time. Therefore, there is no single, one-size-fits-all time for everyone, but rather a different, subjective time for each individual. We need to acknowledge the existence of different inter-individual times but also intra-individual times, to which different functions and different rhythms are attached, depending on the system of reference. However, the construction of these time perceptions and representations is influenced by objective factors (physiological, physical and cognitive) related to neuroscience which will be presented and discussed in this article. Thus, studying representation and perception of time lies at the crossroads between neuroscience, human sciences and philosophy. Furthermore, it is possible to identify several constants among the many and various representations of time and their corresponding measures, regardless of the system of time reference. These include the notion of movements repeated in a stable rhythmic pattern involving the recurrence of the same interval of time, which enables us to define units of time of equal and invariable duration. This rhythmicity is also found at a physiological level and contributes through circadian rhythms, in particular the melatonin rhythm, to the existence of a biological time. Alterations of temporality in mental disorders will be also discussed in this article illustrated by certain developmental disorders such as autism spectrum disorders. In particular, the hypothesis will be developed that children with autism would need to create discontinuity out of continuity through stereotyped behaviors and/or interests. This discontinuity repeated at regular intervals could have been

  19. Supramodal representation of emotions.

    Klasen, Martin; Kenworthy, Charles A; Mathiak, Krystyna A; Kircher, Tilo T J; Mathiak, Klaus


    Supramodal representation of emotion and its neural substrates have recently attracted attention as a marker of social cognition. However, the question whether perceptual integration of facial and vocal emotions takes place in primary sensory areas, multimodal cortices, or in affective structures remains unanswered yet. Using novel computer-generated stimuli, we combined emotional faces and voices in congruent and incongruent ways and assessed functional brain data (fMRI) during an emotional classification task. Both congruent and incongruent audiovisual stimuli evoked larger responses in thalamus and superior temporal regions compared with unimodal conditions. Congruent emotions were characterized by activation in amygdala, insula, ventral posterior cingulate (vPCC), temporo-occipital, and auditory cortices; incongruent emotions activated a frontoparietal network and bilateral caudate nucleus, indicating a greater processing load in working memory and emotion-encoding areas. The vPCC alone exhibited differential reactions to congruency and incongruency for all emotion categories and can thus be considered a central structure for supramodal representation of complex emotional information. Moreover, the left amygdala reflected supramodal representation of happy stimuli. These findings document that emotional information does not merge at the perceptual audiovisual integration level in unimodal or multimodal areas, but in vPCC and amygdala. PMID:21940454

  20. Spatial representation of soundscape

    Boubezari, Mohammed; Bento Coelho, Jos-Luis


    For the last 30 years the concept of soundscape has been largely adopted in many scientific disciplines and by the urban experts for the benefit of a better comprehension and management of the sound environment. However, the spatial representation of the soundscape as a simple tool for the description, management or composition of sound environment is always needed. In this article a method is presented for the spatial sound representation with differentiated sources. The first results are shown. This method gives an account of the soundscape as close as possible to the way it can be perceived by the listener in each location. This method generates qualitative sound maps in a reduced urban scale, based on in situ measurements and on the implication of the measuring subject perception. The maps are sufficient enough to isolate many sound sources of the overall sound field. In this manner, sound quality refers to the sound attribute of a perceived object. It is neither an aesthetic judgment nor traditional psychoacoustics criteria. Concrete examples of application to squares in the city of Lisbon will be shown and discussed. The limits and the prospects of such a qualitative representation will also be presented and discussed.

  1. Comprehension and Representation in Translation



    Transhfion is the faithful rcpresentation in one language of the thought, content, feeling and style written in another language. It involves two processes: comprehension and representation. Correct comprehension is the base for adequate representation. Criteria for good representation lies in two points: the version should be faithful to the original, and the version should be as intelligible as possible.

  2. Maximally Informative Hierarchical Representations of High-Dimensional Data

    Steeg, Greg Ver


    We consider a set of probabilistic functions of some input variables as a representation of the inputs. We present bounds on how informative a representation is about input data. We extend these bounds to hierarchical representations so that we can quantify the contribution of each layer towards capturing the information in the original data. The special form of these bounds leads to a simple, bottom-up optimization procedure to construct hierarchical representations that are also maximally informative about the data. This optimization has linear computational complexity and constant sample complexity in the number of variables. These results establish a new approach to unsupervised learning of deep representations that is both principled and practical. We demonstrate the usefulness of the approach on both synthetic and real-world data.

  3. Representations of stem cell clinics on Twitter.

    Kamenova, Kalina; Reshef, Amir; Caulfield, Timothy


    The practice of travelling abroad to receive unproven and unregulated stem cell treatments has become an increasingly problematic global phenomenon known as 'stem cell tourism'. In this paper, we examine representations of nine major clinics and providers of such treatments on the microblogging network Twitter. We collected and conducted a content analysis of Twitter posts (n = 363) by these establishments and by other users mentioning them, focusing specifically on marketing claims about treatment procedures and outcomes, discussions of safety and efficacy of stem cell transplants, and specific representations of patients' experiences. Our analysis has shown that there were explicit claims or suggestions of benefits associated with unproven stem cell treatments in approximately one third of the tweets and that patients' experiences, whenever referenced, were presented as invariably positive and as testimonials about the efficacy of stem cell transplants. Furthermore, the results indicated that the tone of most tweets (60.2 %) was overwhelmingly positive and there were rarely critical discussions about significant health risks associated with unproven stem cell therapies. When placed in the context of past research on the problems associated with the marketing of unproven stem cell therapies, this analysis of representations on Twitter suggests that discussions in social media have also remained largely uncritical of the stem cell tourism phenomenon, with inaccurate representations of risks and benefits for patients. PMID:24970380

  4. Study on Literature Representation of Zhuhai City Image

    Ruihui Han


    This paper discusses the representation of Zhuhai as a special economic zone and famous tourist city in literature. Since Zhuhai was set up, most native writers in Zhuhai have showed narration of struggling experience in “an alien land” for Zhuhai representation. But such literary works benefit little for effectively establishing Zhuhai’s positive city image and confirming its subject identity and spirit. Native writers in Zhuhai should consciously create positive and healthy social climate, ...

  5. Conceptual representations in goal-directed decision making

    Shea, N; Krug, K.; Tobler, PN


    Emerging evidence suggests that the long-established distinction between habit-based and goal-directed decision-making mechanisms can also be sustained in humans. Although the habit-based system has been extensively studied in humans, the goal-directed system is less well characterized. This review brings to that task the distinction between conceptual and nonconceptual representational mechanisms. Conceptual representations are structured out of semantic constituents (concepts)--the use of w...

  6. Learning warps object representations in the ventral temporal cortex

    Clarke, Alex; Pell, Philip J.; Ranganath, Charan; Tyler, Lorraine K.


    The human ventral temporal cortex (VTC) plays a critical role in object recognition. Although it is well established that visual experience shapes VTC object representations, the impact of semantic and contextual learning is unclear. In this study, we tracked changes in representations of novel visual objects that emerged after learning meaningful information about each object. Over multiple training sessions, participants learned to associate semantic features (e.g. ?made of wood?, ?floats?)...

  7. The Animals (Scientific Procedures) (Procedure for Representations) Rules 1986

    Her Majesty's Stationary Office


    Section 12 of the Animals (Scientific Procedures) (Procedure for Representations) Rules 1986 to make representations to a legally qualified person appointed by the Secretary of State on a person who has applied for or holds a personal or project licence or a certificate of designation of a scientific procedure, breeding or supplying establishment under that Act where the Secretary of State proposes to refuse such a licence or certificate or to vary or revoke it otherwise than at the re...

  8. Medical Knowledge Representation System

    Buchtela, David; Peleška, Jan; Zvolský, Miroslav; Zvárová, Jana

    Amsterdam : IOS Press, 2008 - (Andersen, S.; Klein, G.; Schulz, S.; Aarts, J.; Mazzoleni, M.), s. 377-382 ISBN 978-1-58603-864-9. - (Studies in Health Technology and Informatics. 136). [MIE 2008. International Congress of the European Federation for Medical Informatics /21./. Göteborg (SE), 25.05.2008-28.05.2008] R&D Projects: GA MŠk(CZ) 1M06014 Institutional research plan: CEZ:AV0Z10300504 Keywords : knowledge representation * GLIF model * ontology Subject RIV: IN - Informatics, Computer Science

  9. Representations of commonsense knowledge

    Davis, Ernest


    Representations of Commonsense Knowledge provides a rich language for expressing commonsense knowledge and inference techniques for carrying out commonsense knowledge. This book provides a survey of the research on commonsense knowledge.Organized into 10 chapters, this book begins with an overview of the basic ideas on artificial intelligence commonsense reasoning. This text then examines the structure of logic, which is roughly analogous to that of a programming language. Other chapters describe how rules of universal validity can be applied to facts known with absolute certainty to deduce ot

  10. Music as Representational Art

    Walker, Daniel


    ABSTRACT OF THE DISSERTATIONVolume IMusic as Representational ArtVolume IIAwakeningbyDaniel WalkerDoctor of Philosophy in MusicUniversity of California, Los Angeles, 2014Professor Ian Krouse, ChairThere are two volumes to this dissertation; the first is a monograph, and the second is a musical composition, both of which are described below.Volume IMusic is a language that can be used to express a vast range of ideas and emotions. It has been part of the human experience since before recorded ...

  11. Between Representation and Eternity

    Atzbach, Rainer


    This paper seeks to explore how prayer and praying practice are reflected in archaeological sources. Apart from objects directly involved in the personal act of praying, such as rosaries and praying books, churches and religious foundations played a major role in the medieval system of intercession....... At death, an indi- vidual’s corpse and burial primarily reflect the social act of representation during the funeral. The position of the arms, which have incorrectly been used as a chronological tool in Scandinavia, may indicate an evolution from a more collective act of prayer up to the eleventh...

  12. Concrete Representation and Separability Criteria for Symmetric Quantum State

    Li, Chang'e.; Tao, Yuanhong; Zhang, Jun; Li, Linsong; Nan, Hua


    Using the typical generators of the special unitary groups S U(2), the concrete representation of symmetric quantum state is established, then the relations satisfied by those coefficients in the representation are presented. Based on the representation of density matrix, the PPT criterion and CCNR criterion are proved to be equivalent on judging the separability of symmetric quantum states. Moreover, it is showed that the matrix Γ ρ of symmetric quantum state only has five efficient entries, thus the calculation of ∥Γ ρ ∥ is simplified. Finally, the quantitative expressions of real symmetric quantum state under the ∥Γ ρ ∥ separability criterion are obtained.

  13. Mapping class group representations from Drinfeld doubles of finite groups

    Fjelstad, Jens


    We investigate representations of mapping class groups of surfaces that arise from the untwisted Drinfeld double of a finite group G, focusing on surfaces without marked points or with one marked point. We obtain concrete descriptions of such representations in terms of finite group data. This allows us to establish various properties of these representations. In particular we show that they have finite images, and that for surfaces of genus at least 3 their restriction to the Torelli group is non-trivial iff G is non-abelian.

  14. Knowledge representation with SOA

    Daniela Gotseva


    Full Text Available This paper addresses the problem of supporting the software development process through the artificial intelligence. The expert systems could advise the Domain Engineer in programming without the detailed experience in programming languages. He will use and integrate, with the help of deductive database and domain knowledge, the previously developed software components to new complex functionalities. The objective of this document is to provide the knowledge representation about atomic Web Services which will be registered as the facts in the deductive database. The author proposes to use the decision rules in decision tables for representing the service model which consists of semantic specification, interface description, service quality (QoS, non-functional properties. Also the use of Domain Specific Languages (DSL for modeling Domain Engineers re-quests to the expert system will be considered within this document. As the illustrative use case for described knowledge representation the author proposes the domain of SOA-based geographic information systems (GIS which represent a new branch of information and communication technologies.

  15. Social Representations of Intelligence

    Elena Zubieta


    Full Text Available The article stresses the relationship between Explicit and Implicit theories of Intelligence. Following the line of common sense epistemology and the theory of Social Representations, a study was carried out in order to analyze naive’s explanations about Intelligence Definitions. Based on Mugny & Carugati (1989 research, a self-administered questionnaire was designed and filled in by 286 subjects. Results are congruent with the main hyphotesis postulated: A general overlap between explicit and implicit theories showed up. According to the results Intelligence appears as both, a social attribute related to social adaptation and as a concept defined in relation with contextual variables similar to expert’s current discourses. Nevertheless, conceptions based on “gifted ideology” still are present stressing the main axes of Intelligence debate: biological and sociological determinism. In the same sense, unfamiliarity and social identity are reaffirmed as organizing principles of social representation. The distance with the object -measured as the belief in intelligence differences as a solve/non solve problem- and the level of implication with the topic -teachers/no teachers- appear as discriminating elements at the moment of supporting specific dimensions. 

  16. At immature mossy fibers-CA3 connections, activation of presynaptic GABAB receptors by endogenously released GABA contributes to synapses silencing

    Victoria F Safiulina


    Full Text Available Early in postnatal life correlated GABAergic activity in the hippocampus is thought to play a crucial role in synaptogenesis and in the development of adult neuronal networks. Unlike adulthood, at this developmental stage, mossy fibers (MF which are the axons of granule cells, release GABA into CA3 principal cells and interneurons. Here, we tested the hypothesis that at MF-CA3 connections, tonic activation of GABAB autoreceptors by GABA is responsible for the low probability of release and synapse silencing. Blocking GABAB receptors with CGP55845 enhanced the probability of GABA release and switched on silent synapses while the opposite was observed with baclofen. Both these effects were presynaptic and were associated with changes in paired-pulse ratio and coefficient of variation. In addition, enhancing the extracellular GABA concentration by repetitive stimulation of MF or by blocking the GABA transporter GAT-1, switched off active synapses, an effect that was prevented by CGP55845. In the presence of CGP55845, stimulation of MF induced synaptic potentiation. The shift of EGABA from the depolarizing to the hyperpolarizing direction with bumetanide, a blocker of the cation-chloride co-transporter NKCC1, prevented synaptic potentiation and caused synaptic depression, suggesting that the depolarizing action of GABA observed in the presence of CGP55845 is responsible for the potentiating effect. It is proposed that, activation of GABAB receptors by spillover of GABA from MF terminals reduces the probability of release and contributes to synapses silencing. This would act as a filter to prevent excessive activation of the auto-associative CA3 network and the emergence of seizures.

  17. Expression of c-Fos protein in medial septum/diagonal band of Broca and CA3 region, associated with the temporary inactivation of the supramammillary area.

    Aranda, Lourdes


    The supramammillary (SuM) area is part of the diencephalic nuclei comprising the mammillary bodies, and is a key structure in the memory and spatial learning processes. It is a critical region in the modulation/generation of hippocampal theta rhythm. In addition, many papers have recently shown a clear involvement of this structure in the processes of spatial learning and memory in animal models, although it is still not known how it modulates spatial navigation and response emotional. The aim of the present research was to study the effect of the temporary inactivation of the SuM area on synaptic plasticity of crucial structures in the formation of spatial memory and emotional response. Sprague-Dawley rats were asigned in three groups: a control group where the animals were not subjected to any treatment, and two groups where the rats received microinjections of tetrodotoxin (TTX) in the SuM area (5ng diluted in 0.5μl of saline) or saline (0.5μl). The microinjections were administered 90min before the perfusion. Later, cellular activity in medial septum/diagonal band of Broca (MS/DBB) and CA3 region of the dorsal hippocampus was assessed, by measuring the immediate early gene c-fos. The results show a clear hiperactivity cellular in medial septum/diagonal band of Broca and a clear hypoactivity cellular in the CA3 region of the hippocampus when there was a functional inactivation of the SuM area. It suggests that the SuM area seems to be part of the connection and information input pathways to CA3 region of the hippocampal formation, key for proper functioning in spatial memory and emotional response. PMID:26802745

  18. Effect of tolbutamide, glyburide and glipizide administered supraspinally on CA3 hippocampal neuronal cell death and hyperglycemia induced by kainic acid in mice.

    Kim, Chea-Ha; Park, Soo-Hyun; Sim, Yun-Beom; Kim, Sung-Su; Kim, Su-Jin; Lim, Su-Min; Jung, Jun-Sub; Suh, Hong-Won


    Sulfonylureas are widely used oral drugs for the treatment of type II diabetes mellitus. In the present study, the effects of sulfonylureas administered supraspinally on kainic acid (KA)-induced hippocampal neuronal cell death and hyperglycemia were studied in ICR mice. Mice were pretreated intracerebroventricularly (i.c.v.) with 30μg of tolbutamide, glyburide or glipizide for 10min and then, mice were administered i.c.v. with KA (0.1μg). The neuronal cell death in the CA3 region in the hippocampus was assessed 24h after KA administration and the blood glucose level was measured 30, 60, and 120min after KA administration. We found that i.c.v. pretreatment with tolbutamide, glyburide or glipizide attenuated the KA-induced neuronal cell death in CA3 region of the hippocampus and hyperglycemia. In addition, KA administered i.c.v. caused an elevation of plasma corticosterone level and a reduction of the plasma insulin level. The i.c.v. pretreatment with tolbutamide, glyburide or glipizide attenuated KA-induced increase of plasma corticosterone level. Furthermore, i.c.v. pretreatment with tolbutamide, glyburide or glipizide causes an elevation of plasma insulin level. Glipizide, but not tolbutamide or glyburide, pretreated i.c.v. caused a reversal of KA-induced hypoinsulinemic effect. Our results suggest that supraspinally administered tolbutamide, glyburide and glipizide exert a protective effect against KA-induced neuronal cells death in CA3 region of the hippocampus. The neuroprotective effect of tolbutamide, glyburide and glipizide appears to be mediated by lowering the blood glucose level induced by KA. PMID:24713348

  19. Social Representations of Responsibility in Guatemalan Students

    Humberto Emilio Aguilera Arévalo


    Full Text Available The responsibility is a key concept in the twentieth century because it establishes a connection between the individual and society. Recent studies analyze the responsibility as a relational concept that connects the individual to an event and its outcomes. In that sense, the responsibility may be linked to Markova perspective on dialogicality and social representations because it activates the Ego-Alter-Object dynamic: being responsible for something (Ego toward someone (Alter, and in relation to an instance (object. This paper analyzes the social representations of responsibility in a sample of 296 university students from Guatemala, who answered six stimulus words I Responsible, I Irresponsible, Responsible Guatemalan, Irresponsible Guatemalan, Responsible European and Irresponsible European, using the natural semantic networks technique. Subsequently two questionnaires were made; one about responsibility and irresponsibility on a personal, in group and out group level, based on semantic networks obtained. Finally, factor analysis and hierarchical cluster analysis were made.

  20. Local sparse representation for astronomical image denoising

    杨阿锋; 鲁敏; 滕书华; 孙即祥


    Motivated by local coordinate coding(LCC) theory in nonlinear manifold learning, a new image representation model called local sparse representation(LSR) for astronomical image denoising was proposed. Borrowing ideas from surrogate function and applying the iterative shrinkage-thresholding algorithm(ISTA), an iterative shrinkage operator for LSR was derived. Meanwhile, a fast approximated LSR method by first performing a K-nearest-neighbor search and then solving a l1optimization problem was presented under the guarantee of denoising performance. In addition, the LSR model and adaptive dictionary learning were incorporated into a unified optimization framework, which explicitly established the inner connection of them. Such processing allows us to simultaneously update sparse coding vectors and the dictionary by alternating optimization method. The experimental results show that the proposed method is superior to the traditional denoising method and reaches state-of-the-art performance on astronomical image.

  1. Aging Impairs the Late Phase of Long-Term Potentiation at the Medial Perforant Path-CA3 Synapse in Awake Rats

    Dieguez, Dario; Barea-Rodriguez, Edwin J.


    The effects of aging on long-term potentiation (LTP) in the dentate gyrus (DG) and CA1 are well documented, but LTP at the medial perforant path (MPP)-CA3 synapse of aged animals has remained unexplored. Because the MPP-DG and Schaffer-collateral-CA1 synapses account for only about 20% of total hippocampal synapses, global understanding of how aging affects hippocampal plasticity has remained limited. Much is known about LTP induction in the hippocampal formation, whereas the mechanisms that ...

  2. Sub-80 femtosecond pulses generation from a diode-pumped mode-locked Nd:Ca3La2(BO3)4 disordered crystal laser.

    Ma, Jie; Pan, Zhongben; Cai, Huaqiang; Yu, Haohai; Zhang, Huaijin; Shen, Deyuan; Tang, Dingyuan


    We experimentally demonstrated a diode-pumped sub-80 fs Nd:Ca3La2(BO3)4 disordered crystal laser. Pumping by an 808 nm fiber coupled laser diode, stable continuous-wave mode-locked pulses as short as 79 fs were achieved with a semiconductor saturable absorber mirror (SESAM). The ultrashort pulses had a repetition rate of ∼98.9  MHz at the central wavelength of about 1068 nm. To the best of our knowledge, this is the first demonstration of sub-100 fs pulses and the shortest mode-locked pulses generated from the Nd3+-doped crystal lasers. PMID:27192242

  3. Analyses of stable isotopes in camelids collagen bones from Tulan Ravine, Atacama Puna, early formative period (CA 3,1000-2,400BP)

    This paper presents the results of isotope analysis (δ13C y δ15N) conducted on bone collagen found in Lama guanicoe and Lama glama remains from Tulan-85 and Tulan-54 archaeological sites. Both sites have been dated to the Early Formative Period (ca. 3,100-2,400 ap) and are located southeast of the Atacama Puna basin. Faunal samples were selected using anatomical and morphometric criteria. The results indicate divergences in the diets of both species, reflecting vegetation variation in the Tulan Quebrada caused by altitude differences and linked to hunting and herding areas

  4. Evidence for the coexistence of low-dimensional magnetism and long-range order in Ca3CoRhO6

    Loewenhaupt, M.; Schaefer, W.; Niazi, A.; Sampathkumaran, E. V.


    We report the results of neutron powder diffraction studies on the spin-chain compound Ca3CoRhO6 in the temperature range 3 to 293 K. Bragg peaks due to magnetic ordering start appearing below about 100 K. The most interesting observation is that there is a diffuse magnetic peak superimposed over the strongest magnetic Bragg peak. The diffuse magnetic intensity is observed below as well above 100 K. This finding provides a new insight into the physics of this compound as though the low-dimens...

  5. mGluR2 acts through inhibitory Gα subunits to regulate transmission and long-term plasticity at hippocampal mossy fiber-CA3 synapses

    Nicholls, Russell E.; ZHANG, XIAO-LEI; Bailey, Christopher P.; Conklin, Bruce R; Kandel, Eric R.; Stanton, Patric K.


    Presynaptic inhibitory G protein-coupled receptors play a critical role in regulating transmission at a number of synapses in the central and peripheral nervous system. We generated transgenic mice that express a constitutively active form of an inhibitory Gα subunit to examine the molecular mechanisms underlying the actions of one such receptor, metabotropic glutamate receptor (mGluR) 2, at mossy fiber-CA3 synapses in the hippocampus. mGluR2 participates in at least three types of mossy fibe...

  6. Kinetic arrest of field-temperature induced first order phase transition in quasi-one dimensional spin system Ca3Co2O6

    De, Santanu; Kumar, Kranti; Banerjee, A.; Chaddah, P.


    We have found that the geometrically frustrated spin chain compound Ca3Co2O6 belonging to Ising like universality class with uniaxial anisotropy shows kinetic arrest of first order intermediate phase (IP) to ferrimagnetic (FIM) transition. In this system, dc magnetization measurements followed by different protocols suggest the coexistence of high temperature IP with equilibrium FIM phase in low temperature. Formation of metastable state due to hindered first order transition has also been probed through cooling and heating in unequal field (CHUF) protocol. Kinetically arrested high temperature IP appears to persist down to almost the spin freezing temperature in this system.

  7. SCRAPPER regulates the thresholds of long-term potentiation/depression, the bidirectional synaptic plasticity in hippocampal CA3-CA1 synapses.

    Takagi, Hiroshi; Setou, Mitsutoshi; Ito, Seiji; Yao, Ikuko


    SCRAPPER, which is an F-box protein encoded by FBXL20, regulates the frequency of the miniature excitatory synaptic current through the ubiquitination of Rab3-interacting molecule 1. Here, we recorded the induction of long-term potentiation/depression (LTP/LTD) in CA3-CA1 synapses in E3 ubiquitin ligase SCRAPPER-deficient hippocampal slices. Compared to wild-type mice, Scrapper-knockout mice exhibited LTDs with smaller magnitudes after induction with low-frequency stimulation and LTPs with larger magnitudes after induction with tetanus stimulation. These findings suggest that SCRAPPER regulates the threshold of bidirectional synaptic plasticity and, therefore, metaplasticity. PMID:23316391

  8. SCRAPPER Regulates the Thresholds of Long-Term Potentiation/Depression, the Bidirectional Synaptic Plasticity in Hippocampal CA3-CA1 Synapses

    Hiroshi Takagi; Mitsutoshi Setou; Seiji Ito; Ikuko Yao


    SCRAPPER, which is an F-box protein encoded by FBXL20, regulates the frequency of the miniature excitatory synaptic current through the ubiquitination of Rab3-interacting molecule 1. Here, we recorded the induction of long-term potentiation/depression (LTP/LTD) in CA3-CA1 synapses in E3 ubiquitin ligase SCRAPPER-deficient hippocampal slices. Compared to wild-type mice, Scrapper-knockout mice exhibited LTDs with smaller magnitudes after induction with low-frequency stimulation and LTPs with la...

  9. SCRAPPER Regulates the Thresholds of Long-Term Potentiation/Depression, the Bidirectional Synaptic Plasticity in Hippocampal CA3-CA1 Synapses

    Hiroshi Takagi


    Full Text Available SCRAPPER, which is an F-box protein encoded by FBXL20, regulates the frequency of the miniature excitatory synaptic current through the ubiquitination of Rab3-interacting molecule 1. Here, we recorded the induction of long-term potentiation/depression (LTP/LTD in CA3-CA1 synapses in E3 ubiquitin ligase SCRAPPER-deficient hippocampal slices. Compared to wild-type mice, Scrapper-knockout mice exhibited LTDs with smaller magnitudes after induction with low-frequency stimulation and LTPs with larger magnitudes after induction with tetanus stimulation. These findings suggest that SCRAPPER regulates the threshold of bidirectional synaptic plasticity and, therefore, metaplasticity.

  10. Studies on the new superconducting system (RE) Ba2Ca3Sr4Cu5Ox (RE=Gd, Ho & Dy)

    Arumugam, S.


    Superconducting studies have been carried out in the new high TC (50-65K) system (RE)Ba2Ca3Sr4Cu5OX [(RE) 12345] with RE=Gd, Ho&Dy. The unit cell dimensions are of the order of a=5.44 °A, b=5.46°A and c=14.62°A. The data above the diamagnetic onset and below the upturn temperature due to ordering were analyzed to yield the effective magnetic moments (Peff) of the rare earth ions.