Search results for "void"
showing 10 items of 435 documents
Temperamental characteristics in childhood migraine without aura: a multicenter study
2013
Maria Esposito,1 Rosa Marotta,2 Beatrice Gallai,3 Lucia Parisi,4 Giuseppina Patriciello,1 Serena Marianna Lavano,2 Giovanni Mazzotta,5 Michele Roccella,4 Marco Carotenuto11Center for Childhood Headache, Clinic of Child and Adolescent Neuropsychiatry, Department of Mental Health, Physical and Preventive Medicine, Second University of Naples, Naples, Italy; 2Department of Psychiatry, "Magna Graecia" University of Catanzaro, Catanzaro, Italy; 3Unit of Child and Adolescent Neuropsychiatry, University of Perugia, Perugia, Italy; 4Child Neuropsychiatry, Department of Psychology, University of Palermo, Palermo, Italy; 5Unit of Child and Adolescent Neuropsychiatry, AUSL Umbria 2, …
Understanding the Multiple Length Scales Describing the Structure of Bottle-brush Polymers by Monte Carlo Simulation Methods
2011
Bottle-brush polymers contain a long flexible macromolecule as a backbone to which flexible side chains are grafted. Through the choice of the grafting density and the length of the side chains the local stiffness of this cylindrical molecular brush can be controlled, but a quantitative understanding of these phenomena is lacking. Monte Carlo simulation results are presented and discussed which address this issue, extractingmesoscopic length scales (such as the cross-sectional radius, persistence length, and contour length of these objects). Large-scale simulations of the bond fluctuation model are combined with simulations of the simple selfavoiding walk (SAW) model with flexibility contro…
Behavioural studies on rats injected with l-cycloserine and other compounds
1964
l-cycloserine, a cyclic derivative of O-substituted hydroxylamine, causes the suppression of the conditioned avoidance reaction in the rat. The subsequent injection of equimolar amounts of pyridoxine hydrochloride is responsible for a complete reversal of this suppression. The suppression of the conditioned response is not observed with the d-isomer of cycloserine. Isoniazid is a strong antagonist of l-cycoserine. Changes in the brain level of GABA under several conditions are described. These changes suggest though do not establish a relationship between the block of the conditioned response and the elevation of the aminoacid above its physiological concentration.
The effects of castration and of progestin-oestrogen combinations upon avoidance condtioning in female rats
1970
Summary Using avoidance conditioning the authors show that female rats, three months after castration, emit a lower number of responses. Isolation has no effect whatever on rats, whether normal or castrated. Brief treatment with progestin-oestrogen combinations, interrupted 60 hours before the commencement of the session, brings the behaviour of castrated rats back to the norm. Identical effects occur with the use of a cortical stimulating drug (methylphenidate); while, the action of this drug soon ceases, the effect of hormonal treatment lasts for the duration of the experiments. The results are discussed with reference to the significance to be attributed to the experiments.
Computational evidence in favor of a two-state, two-mode model of the retinal chromophore photoisomerization
2000
In this paper we use ab initio multiconfigurational second-order perturbation theory to establish the intrinsic photoisomerization path model of retinal chromophores. This is accomplished by computing the ground state ( S 0 ) and the first two singlet excited-state ( S 1 , S 2 ) energies along the rigorously determined photoisomerization coordinate of the rhodopsin chromophore model 4- cis -γ-methylnona-2,4,6,8-tetraeniminium cation and the bacteriorhodopsin chromophore model all- trans -hepta-2,4,6-trieniminium cation in isolated conditions. The computed S 2 and S 1 energy profiles do not show any avoided crossing feature along the S 1 reaction path and maintain an energy gap >20 kcal⋅…
ECOLOGICAL LIMITS ON DIVERSIFICATION OF THE HIMALAYAN CORE CORVOIDEA
2012
Within regions, differences in the number of species among clades must be explained by clade age, net diversification rate, or immigration. We examine these alternatives by assessing historical causes of the low diversity of a bird parvorder in the Himalayas (the core Corvoidea, 57 species present), relative to its more species rich sister clade (the Passerida, ∼400 species present), which together comprise the oscine passerines within this region. The core Corvoidea contain ecologically diverse species spanning a large range of body sizes and elevations. Despite this diversity, on the basis of ecological, morphological, and phylogenetic information, we infer that the best explanation for t…
Digital rock physics, chemistry, and biology: challenges and prospects of pore-scale modelling approach
2021
Abstract Conventional and unconventional hydrocarbon rocks have complicated pore structures with heterogeneities distributed over various length scales (from nanometre to centimetre or even larger scales). Effective characterization of the properties of such rocks based on their digital twins is a challenging task. Digital rock physics (DRP) can be used to quantify the structural and morphological parameters of rocks directly and predict flow transport properties at the pore scale. Digital rock chemistry (DRC) or biology (DRB) applies when the changes in pore structures are due to interaction with solutes or microbial activities. Fluid–rock interactions or microbial activities complicate fl…
Indefinitely growing self-avoiding walk.
1985
We introduce a new random walk with the property that it is strictly self-avoiding and grows forever. It belongs to a different universality class from the usual self-avoiding walk. By definition the critical exponent $\ensuremath{\gamma}$ is equal to 1. To calculate the exponent $\ensuremath{\nu}$ of the mean square end-to-end distance we have performed exact enumerations on the square lattice up to 22 steps. This gives the value $\ensuremath{\nu}=0.57\ifmmode\pm\else\textpm\fi{}0.01$.
Observational constraints on the LLTB model
2010
We directly compare the concordance LCDM model to the inhomogeneous matter-only alternative represented by LTB void models. To achieve a "democratic" confrontation we explore LLTB models with non-vanishing cosmological constant and perform a global likelihood analysis in the parameter space of cosmological constant and void radius. In our analysis we carefully consider SNe, Hubble constant, CMB and BAO measurements, marginalizing over spectral index, age of the universe and background curvature. We find that the LCDM model is not the only possibility compatible with the observations, and that a matter-only void model is a viable alternative to the concordance model only if the BAO constrain…
The star formation activity in cosmic voids
2014
Using a sample of cosmic voids identified in the Sloan Digital Sky Survey Data Release 7, we study the star formation activity of void galaxies. The properties of galaxies living in voids are compared with those of galaxies living in the void shells and with a control sample, representing the general galaxy population. Void galaxies appear to form stars more efficiently than shell galaxies and the control sample. This result can not be interpreted as a consequence of the bias towards low masses in underdense regions, as void galaxy subsamples with the same mass distribution as the control sample also show statistically different specific star formation rates. This highlights the fact that g…