581 research outputs found

    Supersymmetric methods in the traveling variable: inside neurons and at the brain scale

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    We apply the mathematical technique of factorization of differential operators to two different problems. First we review our results related to the supersymmetry of the Montroll kinks moving onto the microtubule walls as well as mentioning the sine-Gordon model for the microtubule nonlinear excitations. Second, we find analytic expressions for a class of one-parameter solutions of a sort of diffusion equation of Bessel type that is obtained by supersymmetry from the homogeneous form of a simple damped wave equations derived in the works of P.A. Robinson and collaborators for the corticothalamic system. We also present a possible interpretation of the diffusion equation in the brain contextComment: 14 pages, 1 figur

    Multifractal properties of elementary cellular automata in a discrete wavelet approach of MF-DFA

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    In 2005, Nagler and Claussen (Phys. Rev. E 71 (2005) 067103) investigated the time series of the elementary cellular automata (ECA) for possible (multi)fractal behavior. They eliminated the polynomial background at^b through the direct fitting of the polynomial coefficients a and b. We here reconsider their work eliminating the polynomial trend by means of the multifractal-based detrended fluctuation analysis (MF-DFA) in which the wavelet multiresolution property is employed to filter out the trend in a more speedy way than the direct polynomial fitting and also with respect to the wavelet transform modulus maxima (WTMM) procedure. In the algorithm, the discrete fast wavelet transform is used to calculate the trend as a local feature that enters the so-called details signal. We illustrate our result for three representative ECA rules: 90, 105, and 150. We confirm their multifractal behavior and provide our results for the scaling parametersComment: 8 pages, 5 figures, 21 reference

    Multifractal properties of elementary cellular automata in a discrete wavelet approach of MF-DFA

    Get PDF
    In 2005, Nagler and Claussen (Phys. Rev. E 71 (2005) 067103) investigated the time series of the elementary cellular automata (ECA) for possible (multi)fractal behavior. They eliminated the polynomial background at^b through the direct fitting of the polynomial coefficients a and b. We here reconsider their work eliminating the polynomial trend by means of the multifractal-based detrended fluctuation analysis (MF-DFA) in which the wavelet multiresolution property is employed to filter out the trend in a more speedy way than the direct polynomial fitting and also with respect to the wavelet transform modulus maxima (WTMM) procedure. In the algorithm, the discrete fast wavelet transform is used to calculate the trend as a local feature that enters the so-called details signal. We illustrate our result for three representative ECA rules: 90, 105, and 150. We confirm their multifractal behavior and provide our results for the scaling parametersComment: 8 pages, 5 figures, 21 reference

    A Study of the Critical Cluster Size for Water Monolayer Clusters on a Model AgI Basal Substrate

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    We present a formalism and estimate a critical cluster size for water monolayer formation on a (rigid) model AgI basal substrate. The formalism is modified from that developed for vapor clusters [B. N. Hale and R. C. Ward, J. Stat. Phys. 28, 487 (1982)] and uses a Metropolis Monte Carlo method developed by Squire and Hoover [J. Chem. Phys. 50, 701 (1969)] to determine (Helmholtz) free energy differences for clusters containing n and n-1 molecules. Calculations for clusters of n=1, 2, 3, 4, 6, and 24 water molecules on a model AgI basal face at 265 K are used in a statistical mechanical formalism which assumes that the adsorbed clusters form a mixture of noninteracting ideal gases; the adsorbed monomer concentration is related to the vapor concentration at the same temperature. At water saturation and 265 K a critical cluster size of n*=3 molecules and a steady state nucleation rate (for monolayer formation) of 1023 cm-2 s-1 is predicted. The implications of this for ice nucleation on the model AgI substrate under atmospheric conditions are discussed

    Age Estimation of Burbot Using Pectoral Fin Rays, Branchiostegal Rays and Otoliths

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    Throughout much of its native distribution, burbot (Lota lota) is a species of conservation concern.  Understanding dynamic rate functions is critical for the effective management of sensitive burbot populations, which necessitates accurate and precise age estimates.  Managing sensitive burbot populations requires an accurate and precise non-lethal alternative.  In an effort to identify a non-lethal ageing structure, we compared the precision of age estimates obtained from otoliths, pectoral fin rays, dorsal fin rays and branchiostegal rays from 208 burbot collected from the Green River drainage, Wyoming.  Additionally, we compared the accuracy of age estimates from pectoral fin rays, dorsal fin rays and branchiostegal rays to those of otoliths.  Dorsal fin rays were immediately deemed a poor ageing structure and removed from further analysis.  Age-bias plots of consensus ages derived from branchiostegal rays and pectoral fin rays were appreciably different from those obtained from otoliths.  Exact agreement between readers and reader confidence was highest for otoliths and lowest for branchiostegal rays.  Age-bias plots indicated that age estimates obtained from branchiostegal rays and pectoral fin rays were substantially different from age estimates obtained from otoliths.  Our results indicate that otoliths provide the most precise age estimates for burbot

    Emission Spectroscopic Measurements with an Optical Probe in the NASA Ames IHF Arc Jet Facility

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    An optical probe was designed to measure radiation (from inside the arc heater) incident on a test sample immersed in the arc-heated stream. Currently, only crude estimates are available for this incident radiation. Unlike efforts of the past, where the probe line of sight was inclined to the nozzle centerline, the present development focuses on having the probe line of sight coincide with the nozzle centerline. A fiber-coupled spectrometer was used to measure the spectral distribution of incident radiation in the wavelength range of 225 to 900 nm. The radiation heat flux in this wavelength range was determined by integration of measured emission spectral intensity calibrated to incident irradiance from an integrating sphere. Two arc-heater conditions, corresponding to stream bulk enthalpy levels of 12 and 22 MJ/kg, were investigated in the 13-inch diameter nozzle of the Interaction Heating Facility at NASA Ames Research Center. With the probe placed at a distance of 10 inches from the nozzle exit plane, total radiative heat fluxes were measured to be 3.3 and 8.4 W/sq cm for the 12 and 22 MJ/kg conditions, respectively. About 17% of these radiative fluxes were due to bound-bound radiation from atoms and molecules, while the remaining 83% could be attributed to continua (bound-free and/or free-free). A comparison with spectral simulation based on CFD solutions for the arc-heater flow field and with spectroscopic measurements in the plenum region indicates that more than 95% of the measured radiation is generated in the arc region. The total radiative heat flux from the line radiation could increase by a factor of two through contributions from wavelengths outside the measured range, i.e., from the vacuum ultraviolet (wavelengths less than 225 nm) and the infrared (wavelengths greater than 900 nm). An extrapolation of the continuum radiation to these two wavelength regions was not attempted. In the tested configuration, the measured radiative heat flux accounts for only about 1.4% of the nominal heat flux on a flat face model and therefore is considered negligible. In the 6-inch diameter nozzle, on account of shorter path lengths, the radiation heat flux could be significant. Therefore, future tests in the 6-inch nozzle will have radiometers in addition to the optical probe

    Sonographic Findings in Acute Uterine Inversion

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    We present a case of acute uterine inversion in the third stage of labor in which critical management decisions were facilitated by ultrasound imaging in the operating room. Identification of the ovary and adnexa pulled into the inclination of the inversion allowed successful diagnosis and guidance of uterine replacement

    Controlled sulfur-based engineering confers mouldability to phosphorothioate antisense oligonucleotides

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    Phosphorothioates (PS) have proven their effectiveness in the area of therapeutic oligonucleotides with applications spanning from cancer treatment to neurodegenerative disorders. Initially, PS substitution was introduced for the antisense oligonucleotides (PS ASOs) because it confers an increased nuclease resistance meanwhile ameliorates cellular uptake and in-vivo bioavailability. Thus, PS oligonucleotides have been elevated to a fundamental asset in the realm of gene silencing therapeutic methodologies. But, despite their wide use, little is known on the possibly different structural changes PS-substitutions may provoke in DNA·RNA hybrids. Additionally, scarce information and significant controversy exists on the role of phosphorothioate chirality in modulating PS properties. Here, through comprehensive computational investigations and experimental measurements, we shed light on the impact of PS chirality in DNA-based antisense oligonucleotides; how the different phosphorothioate diastereomers impact DNA topology, stability and flexibility to ultimately disclose pro-Sp S and pro-Rp S roles at the catalytic core of DNA Exonuclease and Human Ribonuclease H; two major obstacles in ASOs-based therapies. Altogether, our results provide full-atom and mechanistic insights on the structural aberrations PS-substitutions provoke and explain the origin of nuclease resistance PS-linkages confer to DNA·RNA hybrids; crucial information to improve current ASOs-based therapies.© The Author(s) 2023. Published by Oxford University Press on behalf of Nucleic Acids Research

    Uso de ultrasonidos para la predicción del valor de la canal en terneros de raza asturiana de los valles

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    In order to improve the meat yield in Asturiana beef cattle, a series of in vivo selection criteria for carcasses are proposed. This information can be obtained by means of ultrasound imaging. The implementation of this technique involves two stages. The first, to put in point the technique and acquire experience in its application, will be developed in the Selection Center at Posada of Llanera (Asturias) with the animals under growth test. The second will be permormed under field conditions, in commercial feedlots and its purpose will be to check whether the taken measurements in the living animal are reasonably correlated with those obtained directly on the carcass. Some results of the first stage are shown.Para mejorar el rendimiento carnicero de la raza Asturiana de los Valles, se pretende incorporar criterios de valoración de canales in vivo en el programa de mejora de dicha raza. Esta información puede obtenerse por métodos ultrasonográficos. La aplicación de la técnica se plantea en dos fases. Una para poner a punto la técnica y adquirir experiencia en su aplicación, se desarrollará en el Centro de Selección de Posada de Llanera (Asturias) con los animales sometidos a testaje. Otra, en condiciones de campo, en cebaderos comerciales para comprobar si las medidas tomadas en el animal vivo están razonablemente correlacionadas con las obtenidas directamente en la canal. Se exponen algunos resultados de la primera fase
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