13,372 research outputs found

    Evolutionary Divergence in Developmental Strategies and Neuromodulatory Control Systems of Two Amphibian Locomotor Networks

    Get PDF
    Attempts to understand the neural mechanisms which produce behaviour must consider both prevailing sensory cues and the central cellular and synaptic changes they direct. At each level, neuromodulation can additionally shape the final output. We have investigated neuromodulation in the developing spinal motor networks in hatchling tadpoles of two closely related amphibians, Xenopus laevis and Rana temporaria to examine the subtle differences in their behaviours that could be attributed to their evolutionary divergence. At the point of hatching, both species can swim in response to a mechanosensory stimulus, however Rana embryos often display a more forceful, non-locomotory coiling behaviour. Whilst the synaptic drive that underlies these behaviours appears similar, subtle inter-specific differences in neuronal properties shape motor outputs in different ways. For example, Rana neurons express N-methyl-D-aspartate (NMDA)/serotonin (5-HT)-dependent oscillations, not present in hatchling Xenopus and many also exhibit a prominent slow spike after-hyperpolarisation. Such properties may endow the spinal circuitry of Rana with the ability to produce a more flexible range of outputs. Finally, we compare the roles of the neuromodulators 5-HT, noradrenaline (NA) and nitric oxide (NO) in shaping motor outputs. 5-HT increases burst durations during swimming in both Xenopus and Rana, but 5-HT dramatically slows the cycle period in Rana with little effect in Xenopus. Three distinct, but presumably homologous NO-containing brainstem clusters of neurons have been described, yet the effects of NO differ between species. In Xenopus, NO slows and shortens swimming in a manner similar to NA, yet in Rana NO and NA elicit the non-rhythmic coiling pattern

    Close pairs of galaxies with different activity levels

    Full text link
    We selected and studied 180 pairs with dV < 800 km/s and Dp < 60 kpc containing Markarian (MRK) galaxies to investigate the dependence of galaxies' integral parameters, star-formation (SF) and active galactic nuclei (AGN) properties on kinematics of pairs, their structure and large-scale environments. Projected radial separation Dp and perturbation level P are better measures of interaction strength than dV. The latter correlates with the density of large-scale environment and with the morphologies of galaxies. Both galaxies in a pair are of the same nature, the only difference is that MRK galaxies are usually righter than their neighbors. Specific star formation rates (SSFR) of galaxies in pairs with smaller Dp or dV is in average 0.5 dex higher than that of galaxies in pairs with larger Dp or dV. Closeness of a neighbor with the same and later morphological type increases the SSFR, while earlier-type neighbors do not increase SSFR. Major interactions/mergers trigger SF and AGN more effectively than minor ones. The fraction of AGNs is higher in more perturbed pairs and pairs with smaller Dp. AGNs typically are in stronger interacting systems than star-forming and passive galaxies. There are correlations of both SSFRs and spectral properties of nuclei between pair members.Comment: 4 pages, 3 figures. arXiv admin note: substantial text overlap with arXiv:1310.024

    Barley yellow dwarf virus - effect on yield of Clipper barley

    Get PDF
    Barley Yellow Dwarf Virus - Effect on Yield of Clipper Barley 77B4, 77MN6. Location: Manjimup Research Station, Bramley Research Station

    Close neighbors of Markarian galaxies. II. Statistics and discussions

    Full text link
    According to the database from the first paper, we select 180 pairs with dV < 800 km/s and Dp < 60 kpc containing Markarian (MRK) galaxies. We study the dependence of galaxies integral parameters, star-formation (SF) and active galactic nuclei (AGN) properties on kinematics of pairs, their structure and large-scale environments. Following main results were obtained: projected radial separation Dp between galaxies correlates with the perturbation level P of the pairs. Both parameters do not correlate with line-of-sight velocity difference dV of galaxies. Dp and P are better measures of interaction strength than dV. The latter correlates with the density of large-scale environment and with the morphologies of galaxies. Both galaxies in a pair are of the same nature, the only difference is that MRK galaxies are usually brighter than their neighbors in average by 0.9 mag. Specific star formation rates (SSFR) of galaxies in pairs with smaller Dp or dV is in average 0.5 dex higher than that of galaxies in pairs with larger Dp or dV. Closeness of a neighbor with the same and later morphological type increases the SSFR, while earlier-type neighbors do not increase SSFR. Major interactions/mergers trigger SF and AGN more effectively than minor ones. The fraction of AGNs is higher in more perturbed pairs and pairs with smaller Dp. AGNs typically are in stronger interacting systems than star-forming and passive galaxies. There are correlations of both SSFRs and spectral properties of nuclei between pair members.Comment: 13 pages, 8 figures, 2 table

    Application of Dynamic System Identification to Timber Bridges

    Full text link
    A method of global nondestructive evaluation for identifying local damage and decay in timber beams was developed in previous analytical studies and verified experimentally using simply supported beams in the laboratory. The method employs experimental modal analysis and an algorithm that monitors changes in modal strain energy between the mode shapes of a damaged structure with respect to the undamaged structure. A simple three-girder bridge was built and tested in a laboratory to investigate the capability and limitations of the method for detecting damage in a multimember timber structure. The laboratory tests showed that the method can correctly detect and locate a simulated pocket of decay inflicted at the end of a girder as well as detect a notch removed from the midspan of a girder. The tests showed that the method can correctly detect damage simultaneously at two locations within the bridge, but also that large magnitudes of damage at one location can mask smaller magnitudes of damage at another location. When a calibrated baseline model is used to represent the undamaged state of the bridge, the results show that the method of nondestructive evaluation is able to detect each case of inflicted damage, but with some increase in localization error

    Herding cats: observing live coding in the wild

    Get PDF
    After a momentous decade of live coding activities, this paper seeks to explore the practice with the aim of situating it in the history of contemporary arts and music. The article introduces several key points of investigation in live coding research and discusses some examples of how live coding practitioners engage with these points in their system design and performances. In the light of the extremely diverse manifestations of live coding activities, the problem of defining the practice is discussed, and the question raised whether live coding will actually be necessary as an independent category

    Plant viruses

    Get PDF
    1. Barley Yellow Dwarf Virus: G.D. McLean, T.N. Khan, J. Sandow. 2. Clover Viruses: G.D. McLean, J. Sandow. BYDV: Survey of incidence - Locations: Esperance (80ES53) sown June 27, 1980 Williams (80NA35) sown June 19, 1980 Kojonup (80KA28) sown June 19, 1980 Bokerup (80MA11) sown July 8, 1980 Jerramungup (80JE14) sown June 26, 1980 Albany (80AL30) sown July 3, 1980 Busselton (80BU3) sown July 8, 1980 Bridgetown (80BR19) sown June s, 1980 Northam (80N026) sown June 16, 1980 All these plots were located at the cultivar variety trial sites. Sites varied considerably in BYDV incidence as well as in rate of disease progress. There was evidence of recovery in some plants, and at Narrogin most infected plants recovered. Taking the mean disease score in the last recording; Manjimup, Albany, Bridgetown, Katanning and Narrogin showed decreasing amounts of incidence in that order. The lower rainfall sites (Katanning and Narrogin) had a much lower incidence of BYDV than the higher rainfall sites. Clover Viruses - 80AL29, 80BR15, 80BU2, 80BY6, 80ES52, 80MA10

    Barley yellow dwarf virus in barley and oats (79MT20, 79PE13) Experimental summary 1979

    Get PDF
    (1) Yield assessments have continued similar to those used in 1977 and 1978. Essentially, plants with symptoms typical of BYDV are marked in the early spring as well as a similar number without symptoms. Yield differences were obtained both for Clipper Barley and an oats variety. (2) Two pilot experiments using viruliferous aphids were carried out at Mount Barker (79MT20) and at South Perth · (79PE13). Both Rhopalosiphum padi and R. maidis were used. Infection at Mt Barker failed, and therefore no data is presented. The Perth experiment was planted on August 31, 1979. The original plan was to have two treatments, i.e. Aphid infestation vs. Control in 4 replications. However, as two different species of aphid became available, the experiment was split into two smaller ones, each using a different species of aphid with 2 replications. RESULTS: See Tables 1 and 2

    1981 Plant viruses

    Get PDF
    1, Clover viruses - 81HA6, 81MA9, 81BR14, 81BY12, 81BH5, 81AL38, 81ES39 OBJECTIVES: To determine the extent of the \u27Dinninup virus\u27 problem (sub. clover mottle). To further assess the incidence of red leaf virus to determine the incidence of bean yellow mosaic virus. To note the incidence of sub. clover stunt virus. A. BYDV: Survey of incidence - 81BU1, 81BU2, 81BR11, 81BR12, 81MA6, 81MA7, 81AL31, 81AL32, 81JE14, 81JE15, 81KA21, 81KA22, 81NA28, 81N031, 81ES38, 81E26. 2. Barley yellow dwarf virus. BYDV: Genotype x insecticide studies - 81MN14, 81MT29, 81E28, 81MN14. BYDV: differences amongst barley genotypes - 81C19, 81WH31, 81BA30. BYDV: Resistance and yield in CV.Shannon and CV. Proctor - 871BR13, 81MA8, 81AL36, 81JE17 Yield per plot and 100 seed weight - Albany 81AL36 Infection of BYDV in cereal genotypes at Manjimup ( 81MN13)
    corecore