2,043 research outputs found
Why Does Rem Sleep Occur? A Wake-Up Hypothesis1
Brain activity differs in the various sleep stages and in conscious wakefulness. Awakening from sleep requires restoration of the complex nerve impulse patterns in neuronal network assemblies necessary to re-create and sustain conscious wakefulness. Herein I propose that the brain uses rapid eye movement (REM) to help wake itself up after it has had a sufficient amount of sleep. Evidence suggesting this hypothesis includes the facts that, (1) when first going to sleep, the brain plunges into Stage N3 (formerly called Stage IV), a deep abyss of sleep, and, as the night progresses, the sleep is punctuated by episodes of REM that become longer and more frequent toward morning, (2) conscious-like dreams are a reliable component of the REM state in which the dreamer is an active mental observer or agent in the dream, (3) the last awakening during a night's sleep usually occurs in a REM episode during or at the end of a dream, (4) both REM and awake consciousness seem to arise out of a similar brainstem ascending arousal system (5) N3 is a functionally perturbed state that eventually must be corrected so that embodied brain can direct adaptive behavior, and (6) cortico-fugal projections to brainstem arousal areas provide a way to trigger increased cortical activity in REM to progressively raise the sleeping brain to the threshold required for wakefulness. This paper shows how the hypothesis conforms to common experience and has substantial predictive and explanatory power regarding the phenomenology of sleep in terms of ontogeny, aging, phylogeny, abnormal/disease states, cognition, and behavioral physiology. That broad range of consistency is not matched by competing theories, which are summarized herein. Specific ways to test this wake-up hypothesis are suggested. Such research could lead to a better understanding of awake consciousness
We Three: My Brain, My Homunculus, and Me
An unconscious sense of the body in all higher mammals is located in somatosensory and motor cortices, colloquially referred to as the Homunculus (H). The time has arrived to consider how H might engage in the dimensions of selfhood that go beyond embodiment. Surely, the neural network modules that process various dimensions of selfhood must at least access and interact with the H or a stored memory of it. In this review, I suggest that our traditional understanding of H is much too simplistic. This review specifies a set of experimental approaches that should enlarge our understanding of the brain mechanisms of selfhood
The effect of soil acidity on crop and pasture production.
SUMMARY The effects of lime and molybdenum applications on wheat and subterranean Clover were studied further. Wheat. In relation to lime use, my aim is to develop soil tests to be used to predict when a soil requires lime to produce maximum yield, and to predict the optimum rate of lime. Using the results from field trials commenced in 1980 and 1981 the soil parameters which may be used to predict lime responses in wheat have been narrowed down. From the relationships between soil data and lime responses it appears that soil ph (measured in 1:5 H20 or 1:5 N kcl), extractable aluminium (in 1:5 N kcl), and exchangeable aluminium expressed as a percentage of total kcl- or NH4Cl- exchangeable cations are poor predictors of the lime responsiveness of wheat on soils in the low rainfall areas of the wheatbelt. The soils are being analysed further to attempt to find an accurate predictor of lime response. Unfortunately, the Government Chemical laboratories which do our analyses, are grossly understaffed, resulting in long delays in analyses being completed. To predict the optimum rate of lime to use on a soil it is necessary to be able to predict the effect of a given rate of lime on the soil properties of interest. It was found that laboratory measurements of ph buffer capacity did not reflect the changes in soil ph induced by lime application at 13 field sites. Molybdenum responses in wheat were common in the 1981 growing season (Table 1). The biggest yield increases were on low yielding trials (80ME3 and 81M02). However, on average, molybdenum application increased yield by 130 kg/ha, or 15 per cent of the yield without molybdenum. All but one (81LG12) of these trial sites have previously received applications of molybdenum. Two long term trials (81M2 and 81LG12) were commenced to study the residual value of molybdenum on acid soils. Subterranean clover grew poorly on all sites and, although molybdenum responses were observed they were not measurable because of the low productivity and high variability of the clover. Progress towards defining a model to predict acidification rates has been made. The conceptual framework of the model has been refined through studies of the scientific literature. A trial to obtain a first approximation of the effect of acidity on the effectiveness of phosphate fertiliser was commenced east of Hyden. 79GE10, 80GE5, 80GE6, 81GL5, 81JE1, 81LG8, 80ME3, 80ME4, 81ME4, 80M29, 80M30, 80M31, 81M2, 81M5/, 81M6, 81M54, 79M027, 80M04, 80M05, 81M02, 81M03, 80NA3, 80NA4, 81N06, 81N07, 79TS1, 79TS2, 80TS6, 81TS1, 81TS2, 81TS30, 81JE2, 81LG12, 79M027
The effect of soil acidity on crop and pasture production
Contents: 1. Summary. 2. Details of research. 2.1 Problem definition glasshouse trial. 2 (a) Vegetative yield affected by topsoil acidity. 2 (b) Root growth in acid subsoil . 2.2 Field Trials. (a) Wheat - Grain yield - Vegetative Growth. (b) Clover. (c) Acidification of soils from the use of nitrogen fertilisers 3. Appendices - trial data. Summary: 1. Problem defining glasshouse trials on soil from 12 sites were conducted in summer/autumn. Results showed that the components of soil acidity affecting wheat growth... 2. The lime and molybdenum requirements of wheat and clover were examined at the sites from which soil came for the glasshouse trials. 3. Calculations of potential acidification rates from the use of nitrogen fertilisers were made- 80GL7, A short summary has been prepared. For those wishing more detail a full report follows the summary. Appendices containing all data from the trials follow the report. Summary: 1. Problem defining glasshouse trials on soil from 12 sites were conducted in summer/autumn… 2. The lime and molybdenum requirements of wheat and clover were examined at the sites from which soil came for the glasshouse trials… 3. Calculations of potential acidification rates from the use of nitrogen fertilisers were made… Details of research: (1)Problem definition - glasshouse trials: (a) Vegetative growth affected by topsoil acidity: 80GL7 Wilroy - 80GE5, Perenjori - 79TS1, Kalannie - 80M04, Kalannie - 80M05, Merredin – (80MI paddock), Bencubbin - 80ME3. Merredin - GL7 (a) (80MI virgin), Yealering – 80N4. Perenjori - 80TS6. Trayning - 80ME4.Gutha - 80GE6. Darkan - 80NA3. Effect of lime and molybdenum on vegetative and grain yield of wheat at eleven sites: 80TS6, 80ME3, 79TS2, 79GE10, 80M30, 80MO4, 80M30, 80MO5, 80GE6, 80GE5, 80ME4, 80NA4. 1. Methods: 1.1 Soil Analysis. 1.2 Nodule rating system. 1.3 Pasture rating (80M29, 30, 31). 2. Glasshouse trials:. 2.1 80GL7 and 7a Soil acidity investigations . 2.2 80GL13 Subsoil acidity and root growth . FIELD TRIALS, PAGE NO. 3.1 80GE5 18 3.2 80GE6 22 3.3 79GE10 27 3.4 80ME3 31 3.5 80ME4 36 3.6 80NA3 41 3.7 80NA4 45 3.8 80M04 48 3.9 80M05 53 3.10 79M027 59 3.11 80TS6 60 3.12 79TS1 65 3.13 79TS2 68 3.14 80M30 70 3.15 80M29 75 3.16 80M31 78 3.17 80Ml 81 3.18 80N3 82 3.19 80WH3 83
Possible indicators for low dimensional superconductivity in the quasi-1D carbide Sc3CoC4
The transition metal carbide Sc3CoC4 consists of a quasi-one-dimensional (1D)
structure with [CoC4]_{\inft} polyanionic chains embedded in a scandium
matrix. At ambient temperatures Sc3CoC4 displays metallic behavior. At lower
temperatures, however, charge density wave formation has been observed around
143K which is followed by a structural phase transition at 72K. Below T^onset_c
= 4.5K the polycrystalline sample becomes superconductive. From Hc1(0) and
Hc2(0) values we could estimate the London penetration depth ({\lambda}_L ~=
9750 Angstroem) and the Ginsburg-Landau (GL) coherence length ({\xi}_GL ~= 187
Angstroem). The resulting GL-parameter ({\kappa} ~= 52) classifies Sc3CoC4 as a
type II superconductor. Here we compare the puzzling superconducting features
of Sc3CoC4, such as the unusual temperature dependence i) of the specific heat
anomaly and ii) of the upper critical field H_c2(T) at T_c, and iii) the
magnetic hysteresis curve, with various related low dimensional
superconductors: e.g., the quasi-1D superconductor (SN)_x or the 2D
transition-metal dichalcogenides. Our results identify Sc3CoC4 as a new
candidate for a quasi-1D superconductor.Comment: 4 pages, 5 figure
Holomorphic Anomaly in Gauge Theories and Matrix Models
We use the holomorphic anomaly equation to solve the gravitational
corrections to Seiberg-Witten theory and a two-cut matrix model, which is
related by the Dijkgraaf-Vafa conjecture to the topological B-model on a local
Calabi-Yau manifold. In both cases we construct propagators that give a
recursive solution in the genus modulo a holomorphic ambiguity. In the case of
Seiberg-Witten theory the gravitational corrections can be expressed in closed
form as quasimodular functions of Gamma(2). In the matrix model we fix the
holomorphic ambiguity up to genus two. The latter result establishes the
Dijkgraaf-Vafa conjecture at that genus and yields a new method for solving the
matrix model at fixed genus in closed form in terms of generalized
hypergeometric functions.Comment: 34 pages, 2 eps figures, expansion at the monopole point corrected
and interpreted, and references adde
The effect of soil acidity on crop and pasture production, summary of experimental results, 1982.
82ME54, 82M024, 82TS33, 82M5, 82ME10, 81TS1, 81TS30, 81LG8, 81M54, 82ME31, 82ME55, 82ME56
Comment on "c-axis Josephson tunneling in -wave superconductors''
This comment points out that the recent paper by Maki and Haas [Phys. Rev. B
{\bf 67}, 020510 (2003)] is completely wrong.Comment: 1 page, submittted to Phys. Rev.
Diffusion on random site percolation clusters. Theory and NMR microscopy experiments with model objects
Quasi two-dimensional random site percolation model objects were fabricate
based on computer generated templates. Samples consisting of two compartments,
a reservoir of HO gel attached to a percolation model object which was
initially filled with DO, were examined with NMR (nuclear magnetic
resonance) microscopy for rendering proton spin density maps. The propagating
proton/deuteron inter-diffusion profiles were recorded and evaluated with
respect to anomalous diffusion parameters. The deviation of the concentration
profiles from those expected for unobstructed diffusion directly reflects the
anomaly of the propagator for diffusion on a percolation cluster. The fractal
dimension of the random walk, , evaluated from the diffusion measurements
on the one hand and the fractal dimension, , deduced from the spin density
map of the percolation object on the other permits one to experimentally
compare dynamical and static exponents. Approximate calculations of the
propagator are given on the basis of the fractional diffusion equation.
Furthermore, the ordinary diffusion equation was solved numerically for the
corresponding initial and boundary conditions for comparison. The anomalous
diffusion constant was evaluated and is compared to the Brownian case. Some ad
hoc correction of the propagator is shown to pay tribute to the finiteness of
the system. In this way, anomalous solutions of the fractional diffusion
equation could experimentally be verified for the first time.Comment: REVTeX, 12 figures in GIF forma
Effective dimensions and percolation in hierarchically structured scale-free networks
We introduce appropriate definitions of dimensions in order to characterize
the fractal properties of complex networks. We compute these dimensions in a
hierarchically structured network of particular interest. In spite of the
nontrivial character of this network that displays scale-free connectivity
among other features, it turns out to be approximately one-dimensional. The
dimensional characterization is in agreement with the results on statistics of
site percolation and other dynamical processes implemented on such a network.Comment: 5 pages, 5 figure
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