Plasma heating, plasma flow and wave production around an electron beam injected into the ionosphere

A brief historical summary of the Minnesota ECHO series and other relevant electron beam experiments is given. The primary purpose of the ECHO experiments is the use of conjugate echoes as probes of the magnetosphere, but beam-plasma and wave studies were also made. The measurement of quasi-dc electric fields and ion streaming during the ECHO 6 experiment has given a pattern for the plasma flow in the hot plasma region extending to 60m radius about the ECHO 6 electron beam. The sheath and potential well caused by ion orbits is discussed with the aid of a model which fits the observations. ELF wave production in the plasma sheath around the beam is briefly discussed. The new ECHO 7 mission to be launched from the Poker Flat range in November 1987 is described

On the influence of the magnetic field of the GSI experimental storage ring on the time-modulation of the EC-decay rates of the H-like mother ions

We investigate the influence of the magnetic field of the Experimental storage ring (ESR) at GSI on the periodic time-dependence of the orbital K-shell electron capture decay $(EC$) rates of the H--like heavy ions. We approximate the magnetic field of the ESR by a uniform magnetic field. Unlike the assertion by Lambiase et al., arXiv: 0811.2302 [nucl-th], we show that a motion of the H-like heavy ion in a uniform magnetic field cannot be the origin of the periodic time-dependence of the EC-decay rates of the H-like heavy ions.Comment: 3 pages, 1 figur

Aspectos ambientais do cultivo de arroz orgânico, biodinâmico e convencional.

Este trabalho tem o objetivo de comparar aspectos ambientais dos diferentes sistemas manejo de arroz irrigado orgânico, biodinâmico e convencional.SIAPEX

Choosing Your Moment: Interruptions in Multimedia Annotation.

In a cooperative mixed-initiative system, timely and effective dialogue between the system and user is important to ensure that both sides work towards producing the most effective results, and this is affected by how disruptive any interruptions are as the user completes their primary task. A disruptive interaction means the user may become irritated with the system, or might take longer to deal with the interruption and provide information that the system needs to continue. Disruption is influenced both by the nature of the interaction and when it takes place in the context of the user’s progress through their main task. We describe an experiment based on a prototype cooperative video annotation system designed to explore the impact of interruptions, in the form of questions posed by the system that the user must address. Our findings demonstrate a preference towards questions presented in context with the content of the video, rather than at the natural opportunities presented by transitions in the video. This differs from previous research which concentrates on interruptions in the form of notifications

Nestin in immature embryonic neurons affects axon growth cone morphology and Semaphorin3a sensitivity

Correct wiring in the neocortex requires that responses to an individual guidance cue vary among neurons in the same location, and within the same neuron over time. Nestin is an atypical intermediate filament expressed strongly in neural progenitors and is thus used widely as a progenitor marker. Here we show a subpopulation of embryonic cortical neurons that transiently express nestin in their axons. Nestin expression is thus not restricted to neural progenitors, but persists for 2–3 d at lower levels in newborn neurons. We found that nestin-expressing neurons have smaller growth cones, suggesting that nestin affects cytoskeletal dynamics. Nestin, unlike other intermediate filament subtypes, regulates cdk5 kinase by binding the cdk5 activator p35. Cdk5 activity is induced by the repulsive guidance cue Semaphorin3a (Sema3a), leading to axonal growth cone collapse in vitro. Therefore, we tested whether nestin-expressing neurons showed altered responses to Sema3a. We find that nestin-expressing newborn neurons are more sensitive to Sema3a in a roscovitine-sensitive manner, whereas nestin knockdown results in lowered sensitivity to Sema3a. We propose that nestin functions in immature neurons to modulate cdk5 downstream of the Sema3a response. Thus, the transient expression of nestin could allow temporal and/or spatial modulation of a neuron’s response to Sema3a, particularly during early axon guidance

Properties of the 5- state at 839 keV in 176Lu and the s-process branching at A = 176

The s-process branching at mass number A = 176 depends on the coupling between the high-K ground state and a low-lying low-K isomer in 176Lu. This coupling is based on electromagnetic transitions via intermediate states at higher energies. The properties of the lowest experimentally confirmed intermediate state at 839 keV are reviewed, and the transition rate between low-K and high-K states under stellar conditions is calculated on the basis of new experimental data for the 839 keV state. Properties of further candidates for intermediate states are briefly analyzed. It is found that the coupling between the high-K ground state and the low-K isomer in 176Lu is at least one order of magnitude stronger than previously assumed leading to crucial consequences for the interpretation of the 176Lu/176Hf pair as an s-process thermometer.Comment: 11 pages, 4 figures accepted for publication in Phys. Rev.