130 research outputs found

    Centrifugally driven electrostatic instability in extragalactic jets

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    The stability problem of the rotation induced electrostatic wave in extragalactic jets is presented. Solving a set of equations describing dynamics of a relativistic plasma flow of AGN jets, an expression of the instability rate has been derived and analyzed for typical values of AGNs. The growth rate was studied versus the wave length and the inclination angle and it has been found that the instability process is much efficient with respect to the accretion disk evolution, indicating high efficiency of the instability.Comment: 7 pages, 4 figure

    Features of the anatomical structure of leaves depending on the high-altitude growth of apricot in Dagestan

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    Background.Β The adaptive changes during the distribution of Prunus armeniaca L. in Dagestan are important for understanding microevolution, structural and functional differentiation processes of populations along environmental gradients based on the organism’s reaction norm. They can be examined by studying leaf anatomical features, having ecologically differentiating significance in natural populations with contrasting growth conditions.Β  Β Materials and methods.Β The material for the study of leaf anatomical features was taken from 7 apricot trees in 3 growing areas of Mountainous Dagestan. Comparative analysis was carried out for 42 morphological, anatomical and index parameters of the lamina and petiole.Β  Β Results.Β The anocytic structure type of the stomatal apparatus was found in all apricot samples. The differences were determined by the degree of stomata submergence depending on the cuticle’s development. Trees from greater heights had more trichomes on the leaf’s upper side than on its underside. Significant differences between the extreme height reference points were recorded for the number of stomata, cells of the lower epidermis, layers of the sclerenchyma, and xylem thickness. Most of the traits of the lamina decreased, and those of the petiole increased with the altitude.Β  Β Conclusion.Β The traits corresponding to the lower and upper altitude limits of P. armeniaca were identified on the basis of the lamina and petiole anatomical features. More xerophytic leaf traits were recorded for the altitudes of 550 m and 1900 m, and mesophytic ones for 1700 m and 1800 m. Endoderm thickness, number of endosperm layers, petiole index, and stomatal index were identified as stable indicators according to the reaction norm within the scope of altitudes: The differences were proved for more plastic traits (number of cells of the upper and lower epidermis, number of stomata, thickness of the lamina and cuticle, and the petiole’s long axis diameter)

    Kelvin-Helmholtz Instability of the Magnetopause of Disc-Accreting Stars

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    This work investigates the short wavelength stability of the magnetopause between a rapidly-rotating, supersonic, dense accretion disc and a slowly-rotating low-density magnetosphere of a magnetized star. The magnetopause is a strong shear layer with rapid changes in the azimuthal velocity, the density, and the magnetic field over a short radial distance and thus the Kelvin-Helmholtz (KH) instability may be important. The plasma dynamics is treated using non-relativistic, compressible (isentropic) magnetohydrodynamics. It is necessary to include the displacement current in order that plasma wave velocities remain less than the speed of light. We focus mainly on the case of a star with an aligned dipole magnetic field so that the magnetic field is axial in the disc midplane and perpendicular to the disc flow velocity. However, we also give results for cases where the magnetic field is at an arbitrary angle to the flow velocity. For the aligned dipole case the magnetopause is most unstable for KH waves propagating in the azimuthal direction perpendicular to the magnetic field which tends to stabilize waves propagating parallel to it. The wave phase velocity is that of the disc matter. A quasi-linear theory of the saturation of the instability leads to a wavenumber (kk) power spectrum ∝kβˆ’1\propto k^{-1} of the density and temperature fluctuations of the magnetopause, and it gives the mass accretion and angular momentum inflow rates across the magnetopause. For self-consistent conditions this mass accretion rate will be equal to the disc accretion rate at large distances from the magnetopause.Comment: 8 pages, 7 figure

    The OscSNS White Paper

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    There exists a need to address and resolve the growing evidence for short-baseline neutrino oscillations and the possible existence of sterile neutrinos. Such non-standard particles require a mass of ∼1\sim 1 eV/c2^2, far above the mass scale associated with active neutrinos, and were first invoked to explain the LSND Ξ½Λ‰ΞΌβ†’Ξ½Λ‰e\bar \nu_\mu \rightarrow \bar \nu_e appearance signal. More recently, the MiniBooNE experiment has reported a 2.8Οƒ2.8 \sigma excess of events in antineutrino mode consistent with neutrino oscillations and with the LSND antineutrino appearance signal. MiniBooNE also observed a 3.4Οƒ3.4 \sigma excess of events in their neutrino mode data. Lower than expected neutrino-induced event rates using calibrated radioactive sources and nuclear reactors can also be explained by the existence of sterile neutrinos. Fits to the world's neutrino and antineutrino data are consistent with sterile neutrinos at this ∼1\sim 1 eV/c2^2 mass scale, although there is some tension between measurements from disappearance and appearance experiments. In addition to resolving this potential major extension of the Standard Model, the existence of sterile neutrinos will impact design and planning for all future neutrino experiments. It should be an extremely high priority to conclusively establish if such unexpected light sterile neutrinos exist. The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, built to usher in a new era in neutron research, provides a unique opportunity for US science to perform a definitive world-class search for sterile neutrinos.Comment: This white paper is submitted as part of the SNOWMASS planning proces

    ΠŸΡ€ΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ ΠΎΠ·ΠΎΠ½ΠΈΡ€ΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΠΏΠ΅Ρ€Ρ„Ρ‚ΠΎΡ€Π°Π½Π° ΠΏΡ€ΠΈ остром ΠΏΠ΅Ρ€ΠΈΡ‚ΠΎΠ½ΠΈΡ‚Π΅

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    The properties of ozonized perfluorane were first studied in the treatment of experimental generalized peritonitis. Experiments were conducted on albino noninbred rats. The model of acute peritonitis, proposed by S. S. Remennik, was used. After simulating peritonitis, the animals were intraperitoneally injected saline solution (Series 1), perfluorane (Series 2), ozonized saline solution (Series 3), ozonized perfluorane (Series 4). All the animals intraperitoneally given saline solution died on days 1β€”7 of the experiment. When ozonized perfluorane was used, all the animals survived. The therapeutic effect of ozonized perfluorane in acute peritonitis was due to the activation of phagocytes and to the antibacterial activity of ozone.Π’ΠΏΠ΅Ρ€Π²Ρ‹Π΅ ΠΈΠ·ΡƒΡ‡Π΅Π½Ρ‹ свойства ΠΎΠ·ΠΎΠ½ΠΈΡ€ΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΠΏΠ΅Ρ€Ρ„Ρ‚ΠΎΡ€Π°Π½Π° ΠΏΡ€ΠΈ Π»Π΅Ρ‡Π΅Π½ΠΈΠΈ ΡΠΊΡΠΏΠ΅Ρ€ΠΈΠΌΠ΅Π½Ρ‚Π°Π»ΡŒΠ½ΠΎΠ³ΠΎ Ρ€Π°Π·Π»ΠΈΡ‚ΠΎΠ³ΠΎ ΠΏΠ΅Ρ€ΠΈΡ‚ΠΎΠ½ΠΈΡ‚Π°. ΠžΠΏΡ‹Ρ‚Ρ‹ ΠΏΡ€ΠΎΠ²Π΅Π΄Π΅Π½Ρ‹ Π½Π° Π±Π΅Π»Ρ‹Ρ… бСспородных крысах. Использовалась модСль острого ΠΏΠ΅Ρ€ΠΈΡ‚ΠΎΠ½ΠΈΡ‚Π° ΠΏΠΎ Π‘. Π‘. Π Π΅ΠΌΠ΅Π½Π½ΠΈΠΊΡƒ. ПослС модСлирования ΠΏΠ΅Ρ€ΠΈΡ‚ΠΎΠ½ΠΈΡ‚Π° ΠΆΠΈΠ²ΠΎΡ‚Π½Ρ‹ΠΌ Π² Π±Ρ€ΡŽΡˆΠ½ΡƒΡŽ ΠΏΠΎΠ»ΠΎΡΡ‚ΡŒ вводились физиологичСский раствор (1-я сСрия), ΠΏΠ΅Ρ€Ρ„Ρ‚ΠΎ-Ρ€Π°Π½ (2-я сСрия), ΠΎΠ·ΠΎΠ½ΠΈΡ€ΠΎΠ²Π°Π½Π½Ρ‹ΠΉ физиологичСский раствор (3-я сСрия), ΠΎΠ·ΠΎΠ½ΠΈΡ€ΠΎΠ²Π°Π½Π½Ρ‹ΠΉ ΠΏΠ΅Ρ€Ρ„Ρ‚ΠΎΡ€Π°Π½ (4-я сСрия). ВсС ΠΆΠΈΠ²ΠΎΡ‚Π½Ρ‹Π΅, ΠΊΠΎΡ‚ΠΎΡ€Ρ‹ΠΌ Π² Π±Ρ€ΡŽΡˆΠ½ΡƒΡŽ ΠΏΠΎΠ»ΠΎΡΡ‚ΡŒ Π²Π²ΠΎΠ΄ΠΈΠ»ΠΈ физиологичСский раствор, ΠΏΠΎΠ³ΠΈΠ±Π»ΠΈ Π½Π° 1β€”7 сутки экспСримСнта. ΠŸΡ€ΠΈ ΠΏΡ€ΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠΈ ΠΎΠ·ΠΎΠ½ΠΈΡ€ΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΠΏΠ΅Ρ€Ρ„Ρ‚ΠΎΡ€Π°Π½Π° всС ΠΆΠΈΠ²ΠΎΡ‚Π½Ρ‹Π΅ Π²Ρ‹ΠΆΠΈΠ»ΠΈ. ВСрапСвтичСский эффСкт ΠΎΠ·ΠΎΠ½ΠΈΡ€ΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΠΏΠ΅Ρ€Ρ„Ρ‚ΠΎΡ€Π°Π½Π° ΠΏΡ€ΠΈ остром ΠΏΠ΅Ρ€ΠΈΡ‚ΠΎΠ½ΠΈΡ‚Π΅ обусловлСн Π°ΠΊΡ‚ΠΈΠ²Π°Ρ†ΠΈΠ΅ΠΉ Ρ„Π°Π³ΠΎΡ†ΠΈΡ‚ΠΈΡ€ΡƒΡŽΡ‰ΠΈΡ… ΠΊΠ»Π΅Ρ‚ΠΎΠΊ ΠΈ Π°Π½Ρ‚ΠΈΠ±Π°ΠΊΡ‚Π΅Ρ€ΠΈΠ°Π»ΡŒΠ½Ρ‹ΠΌ дСйствиСм ΠΎΠ·ΠΎΠ½Π°

    Centrifugally driven relativistic dynamics on curved trajectories

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    Motion of test particles along rotating curved trajectories is considered. The problem is studied both in the laboratory and the rotating frames of reference. It is assumed that the system rotates with the constant angular velocity Ο‰=const\omega = const. The solutions are found and analyzed for the case when the form of the trajectory is given by an Archimedes spiral. It is found that particles can reach infinity while they move along these trajectories and the physical interpretation of their behaviour is given. The analogy of this idealized study with the motion of particles along the curved rotating magnetic field lines in the pulsar magnetosphere is pointed out. We discuss further physical development (the conserved total energy case, when Ο‰β‰ const\omega \ne const) and astrophysical applications (the acceleration of particles in active galactic nuclei) of this theory.Comment: 13 pages, 3 figures, to appear in the vol.35 (July issue) of the "General Relativity and Gravitation

    Measurement of the neutrino component of an anti-neutrino beam observed by a non-magnetized detector

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    Two independent methods are employed to measure the neutrino flux of the anti-neutrino-mode beam observed by the MiniBooNE detector. The first method compares data to simulated event rates in a high purity \numu induced charged-current single \pip (CC1\pip) sample while the second exploits the difference between the angular distributions of muons created in \numu and \numub charged-current quasi-elastic (CCQE) interactions. The results from both analyses indicate the prediction of the neutrino flux component of the pre-dominately anti-neutrino beam is over-estimated - the CC1\pip analysis indicates the predicted \numu flux should be scaled by 0.76Β±0.110.76 \pm 0.11, while the CCQE angular fit yields 0.65Β±0.230.65 \pm 0.23. The energy spectrum of the flux prediction is checked by repeating the analyses in bins of reconstructed neutrino energy, and the results show that the spectral shape is well modeled. These analyses are a demonstration of techniques for measuring the neutrino contamination of anti-neutrino beams observed by future non-magnetized detectors.Comment: 15 pages, 7 figures, published in Physical Review D, latest version reflects changes from referee comment
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