Kinetic Theory and Fast Wind Observations of the Electron Strahl

We develop a model for the strahl population in the solar wind -- a narrow, low-density and high-energy electron beam centered on the magnetic field direction. Our model is based on the solution of the electron drift-kinetic equation at heliospheric distances where the plasma density, temperature, and the magnetic field strength decline as power-laws of the distance along a magnetic flux tube. Our solution for the strahl depends on a number of parameters that, in the absence of the analytic solution for the full electron velocity distribution function (eVDF), cannot be derived from the theory. We however demonstrate that these parameters can be efficiently found from matching our solution with observations of the eVDF made by the Wind satellite's SWE strahl detector. The model is successful at predicting the angular width (FWHM) of the strahl for the Wind data at 1 AU, in particular by predicting how this width scales with particle energy and background density. We find the strahl distribution is largely determined by the local temperature Knudsen number $\gamma \sim |T dT/dx|/n$, which parametrizes solar wind collisionality. We compute averaged strahl distributions for typical Knudsen numbers observed in the solar wind, and fit our model to these data. The model can be matched quite closely to the eVDFs at 1 AU, however, it then overestimates the strahl amplitude at larger heliocentric distances. This indicates that our model may be improved through the inclusion of additional physics, possibly through the introduction of "anomalous diffusion" of the strahl electrons

Magnetohydrodynamic analysis of the stability of the plasmapause

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1981.Microfiche copy available in Archives and Science.Bibliography: leaves 171-173.by Adolfo Figueroa Vinãs.Ph.D

Acoustic Kappa-Density Fluctuation Waves in Suprathermal Kappa Function Fluids

We describe a new wave mode similar to the acoustic wave in which both density and velocity fluctuate. Unlike the acoustic wave in which the underlying distribution is Maxwellian, this new wave mode occurs when the underlying distribution is a suprathermal kappa function and involves fluctuations in the power law index, kappa. This wave mode always propagates faster than the acoustic wave with an equivalent effective temperature and becomes the acoustic wave in the Maxwellian limit as kappa goes to infinity.Comment: 11 pages, 2 figures, in press AS

Análisis comparativo de estructuras empleando método de encamisado y aplicación Sikawrap-600c en edificaciones de cuatro niveles, San Juan de Lurigancho-2022

En el presente proyecto de tesis se cuenta con un objetivo general que es determinar de qué manera el análisis comparativo permitirá el mejor reforzamiento estructural entre el método de encamisado y la aplicación de sikawrap-600C, para una edificación de cuatro niveles en San Juan de Lurigancho 2022. Lo que buscamos es realizar un análisis comparativo tanto técnico y económico que ameriten seguridad ante sismos en un mejor reforzamiento estructural para una edificación de cuatro niveles. Este proyecto es de tipo aplicada con un diseño cuasi experimental, donde referente a lo mencionado se cuenta con respaldos de autores que con sus aportes en conocimientos sobre el tema nos ayuda a desarrollar la investigación con seguridad. Con los estudios, muestras y ensayos realizados y obtenidos se podrá definir cuál es el mejor y adecuado reforzamiento que se debe aplicar en la edificación de tal forma que garantice tiempo de vida útil y la incrementación de resistencia ante los cambios por tipo de uso, se concluye, una vez realizado el análisis comparativo del mejor reforzamiento en dar la mejor alternativa al dueño del predio así como también la parte comparativa del presupuesto que se generara con distintos sistemas de reforzamiento

Highly efficient system for the micropropagation and acclimatization of pineapple in vitro plants (Ananas comosus L. Merr, var. MD2)

The low acclimatization efficiency of pineapple seedlings obtained by in vitro culture has been one of the main limitations to massively scale micropropagation protocols. Various factors may be affecting the successful establishment of in vitro plants to ex vitro conditions, related to the plant and/or the environment and the management of seedlings. The objective of this study was to establish an efficient micropropagation and acclimatization system for the MD2 variety, with a high in vitro multiplication rate and a high greenhouse and field survival of pineapple in vitro plants. In the multiplication phase, the axillary buds were isolated and placed on a semisolid medium and three induction treatments with different concentrations of BAP (1.0, 3.0, 5.0 mg/L) and ANA (2.0 mg/L), were evaluated. After the third subculture, multiple shoots were transferred to a temporary immersion system (BIOMINT). During acclimatization and nursery phases, six treatments with different substrate compositions wereevaluated. The induction treatment IT3 (BAP 5.0 mg/L and ANA 2.0 mg/L) was selected for a significantly high multiplication rate. AT4 treatment (Soil + Coconut fiber + perlite 1:1:1) showed the highest survival rate (95%) and allowed the obtaining of well-developed plants. This system constitutes a valuable technology to introduce in vitro plants to the pineapple production scheme on a commercial scale

Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave

Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA’s Magnetospheric Multiscale (MMS) mission, we utilize Earth’s magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electrons confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. The investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations

Presencia de Pseudablebes Agassizii (Jan, 1863) en Sierra de la Ventana (provincia de Buenos Aires), y confirmación para la provincia de La Pampa

Esta primera cita formal se basa en material depositado en la colección de la Div. Herpetología del Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Los tres ejemplares proceden del partido de Tornquist, Sierra de la Ventana. Corresponden a los números MACN 31772-773, coleccionados por J. Cranwell y G. Gnida y J. Soroka en marzo de 1985; y al número MACN 31774, coleccionado por G. Gnida en abril del mismo año.Asociación Herpetológica Argentin

Asymmetric solar wind electron superthermal distributions

Electron distributions with various degrees of asymmetry associated with the energetic tail population are commonly detected in the solar wind near 1 AU. By numerically solving one-dimensional electrostatic weak turbulence equations the present paper demonstrates that a wide variety of asymmetric energetic tail distributionsmay result. It is found that a wide variety of asymmetric tail formation becomes possible if one posits that the solar wind electrons are initially composed of thermal core plus field-aligned counterstreaming beams, instead of the customary thermal population plus a single beam. It is shown that the resulting nonlinear wave-wave and wave-particle interactions lead to asymmetric nonthermal tails. It is found that the delicate difference in the average beam speeds associated with the forward versus backward components is responsible for the generation of asymmetry in the energetic tail