Multiple Quantum NMR Dynamics in Dipolar Ordered Spin Systems

We investigate analytically and numerically the Multiple Quantum (MQ) NMR dynamics in systems of nuclear spins 1/2 coupled by the dipole-dipole interactions in the case of the dipolar ordered initial state. We suggest two different methods of MQ NMR. One of them is based on the measurement of the dipolar temperature in the quasi-equilibrium state which establishes after the time of order T2 after the MQ NMR experiment. The other method uses an additional resonance 45^0 -pulse after the preparation period of the standard MQ NMR experiment in solids. Many-spin clusters and correlations are created faster in such experiments than in the usual MQ NMR experiments and can be used for the investigation of many-spin dynamics of nuclear spins in solids.Comment: 11 pages, 3 figures. accepted for publication in Physical Review

Formation of plasma around a small meteoroid: 1. Kinetic theory

This article is a companion to Dimant and Oppenheim [2017] https://doi.org/10.1002/2017JA023963.This paper calculates the spatial distribution of the plasma responsible for radar head echoes by applying the kinetic theory developed in the companion paper. This results in a set of analytic expressions for the plasma density as a function of distance from the meteoroid. It shows that at distances less than a collisional mean free path from the meteoroid surface, the plasma density drops in proportion to 1/R where R is the distance from the meteoroid center; and, at distances much longer than the mean‐free‐path behind the meteoroid, the density diminishes at a rate proportional to 1/R2. The results of this paper should be used for modeling and analysis of radar head echoes.This work was supported by NSF grant AGS-1244842. (AGS-1244842 - NSF

Wave-space representation of the electron entropy in the tight-binding approximation

The wave-space expression for the electron entropy averaged with respect to the hard-sphere reference system is obtained in the framework of the tight-binding model. © 2014 I. E. Furman

Self-diffusion coefficient of liquid rubidium

The self-diffusion coefficient of the liquid rubidium at T=312K is calculated in the square-well model within the random phase approximation. A good agreement with available experimental data is achieved. © 2014 I. E. Furman

Analytical Calculation of the Neutrons Spectrum for Direct Measurement of N-N Scattering at Pulsed Reactor Yaguar

Analytical calculation of a single neutron detector counts per YAGUAR reactor pulse is presented and comparison with coincidence scheme is given.Comment: 10 pages, 3 figure

Effect of laser heat treatment on structure and wear resistance of cobalt stellite

The structure and wear resistance of Stellite 6 alloy were studied before and after laser heat treatment. A significant refinement of the microstructure after the heat treatment is noted, the hardness the alloy changed slightly. An increase of wear resistance in shock-abrasive wear at angles of attack of 60-90° as well as metal-to-metal wear with presence of an abrasive layer is shown. © 2019 IOP Publishing Ltd. All rights reserved

The multiple quantum NMR dynamics in systems of equivalent spins with the dipolar ordered initial state

The multiple quantum (MQ) NMR dynamics in the system of equivalent spins with the dipolar ordered initial state is considered. The high symmetry of the MQ Hamiltonian is used in order to develop the analytical and numerical methods for an investigation of the MQ NMR dynamics in the systems consisting of hundreds of spins from "the first principles". We obtain the dependence of the intensities of the MQ NMR coherences on their orders (profiles of the MQ NMR coherences) for the systems of $200 - 600$ spins. It is shown that these profiles may be well approximated by the exponential distribution functions. We also compare the MQ NMR dynamics in the systems of equivalent spins having two different initial states, namely the dipolar ordered state and the thermal equilibrium state in the strong external magnetic field.Comment: 11 pages 4 figure

Commentary: Providing Versus Packaging Support for Bereaved Parents After Perinatal Loss

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73421/1/j.1523-536X.1992.tb00384.x.pd

POROUS CASTING PRODUCTION PROCESS

FIELD: foundry, possibly process for making porous castings.SUBSTANCE: filler with fraction size 0.64 -0.32 mm is heated in furnace and it is poured into heated chill mold whose bottom is communicated with vacuum source. Finely dispersed filler with fraction size 0.32 - 0.16 is poured on layer of first filler. Fraction size of finely dispersed filler consists 0.4 - 0.5 of fraction size of first filler. Then melt is cast on surface of filler. At evacuated condition filler is impregnated with melt. After solidification of casting, portion filled with finely dispersed filler is removed by means of mechanical working. Remaining filler is removed by dissolving it in water.EFFECT: uniform pore distribution in casting.Изобретение относится к литейному производству и может быть использовано при получении пористых отливок. Наполнитель фракции 0,64-0,32 мм нагревают в печи и засыпают в нагретый кокиль, донная часть которого соединена с источником вакуума. Поверх этого слоя наполнителя засыпают мелкодисперсный наполнитель фракции 0,32-0,16 мм. Размер фракции мелкодисперсного наполнителя составляет 0,4-0,5 от размера фракции наполнителя. На поверхность наполнителя заливают расплав. В условиях вакуума осуществляется пропитка наполнителя расплавом. После затвердевания отливки механической обработкой удаляют участок, заполненный мелкодисперсным наполнителем. Остальной наполнитель удаляют растворением в воде. Обеспечивается равномерное распределение пор в отливке

The Effects of Negative Legacies on the Adjustment of Parentally Bereaved Children and Adolescents

This is a report of a qualitative analysis of a sample of bereaved families in which one parent died and in which children scored in the clinical range on the Child Behavior Check List. The purpose of this analysis was to learn more about the lives of these children. They were considered to be at risk of developing emotional and behavioral problems associated with the death. We discovered that many of these “high risk” children had a continuing bond with the deceased that was primarily negative and troubling for them in contrast to a comparison group of children not at risk from the same study. Five types of legacies, not mutually exclusive, were identified: health related, role related, personal qualities, legacy of blame, and an emotional legacy. Coping behavior on the part of the surviving parent seemed to make a difference in whether or not a legacy was experienced as negative