Pressure tensor in the presence of velocity shear: stationary solutions and self-consistent equilibria

Observations and numerical simulations of laboratory and space plasmas in almost collisionless regimes reveal anisotropic and non-gyrotropic particle distribution functions. We investigate how such states can persist in the presence of a sheared flow. We focus our attention on the pressure tensor equation in a magnetized plasma and derive analytical self-consistent plasma equilibria which exhibit a novel asymmetry with respect to the magnetic field direction. These results are relevant for investigating, within fluid models that retain the full pressure tensor dynamics, plasma configurations where a background shear flow is present.Comment: 13 pages, 7 figure

Survey of ear flies (Diptera, Ulidiiae) in maize (Zea mays L.) and a new record of Euxesta mazorca Steyskal in Brazil.

Survey of ear flies (Diptera, Ulidiidae) in maize (Zea mays L.) and a new record of Euxesta mazorca Steyskal in Brazil. Species of Euxesta (Diptera, Ulidiidae), known as silk flies or ear flies, are becoming increasingly important as maize insect pests in South America, although very little is known about them in Brazil. The larvae of some species of this genus initially damage female reproductive tissues, and then the developing kernels on the ear. As a result of feeding, fermentation and associated odors cause complete loss of the grain because it is no longer fit for human or livestock consumption. The main objective of th is work was to evaluate the incidence of Euxesta spp. in Brazilian maize fields and to determine the most prevalent species using two different hydrolyzed protein foods attractants, BioAnastrepha® (hydrolyzed maize protein) and Torula, placed inside McPhail traps. The two species identified were E. eluta Loew and E. mazorca Steyskal, the latter being a new record from Brazil. Between the two species, E. eluta was the more abundant in maize fields. Both attractants were efficient in capturing the two species. However, BioAnastrepha® captured significantly more insects than Torula. Levantamento de mosca-da-espiga (Diptera: Ulidiidae) em milho (Zea mays L.) e primeiro relato de ocorrência de Euxesta mazorca Steyskal no Brasil. Espécies de Euxesta (Diptera, Ulidiidae), conhecidas como moscas do cabelo ou moscas da espiga estão aumentando em importância nas culturas de milho em diferentes países, embora muito pouco se conheça sobre elas no Brasil. As larvas das espécies representativas de Ulidiidae inicialmente danificam a parte reprodutiva feminina da planta e depois os grãos em desenvolvimento. Como resultado da alimentação das larvas ocorre fermentação e odor forte tornando a espiga inapropriada para o consumo humano ou animal. O principal objetivo deste trabalho foi avaliar a incidência de espécies de Euxesta em áreas de produção de milho e identificar as espécies predominantes usando dois atraentes alimentares diferentes à base de proteínas hidrolisáveis, BioAnastrepha® (proteína hidrolisável de milho) e Torula, colocados no interior de armadilha McPhail. As duas espécies identificadas foram E. eluta Loew and E. mazorca Steyskal, registrada pela primeira vez no Brasil. Entre as espécies, E. eluta foi predominante no milho. Ambos os atraentes foram eficientes na captura das duas espécies. No entanto, as armadilhas com BioAnastrepha® capturaram significativamente mais insetos do que aquelas com Torula

Effect of temperature anisotropy on the dynamics of geodesic acoustic modes

In this work, we revisit the linear gyro-kinetic theory of geodesic acoustic modes (GAMs) and derive a general dispersion relation for an arbitrary equilibrium distribution function of ions. A bi-Maxwellian distribution of ions is then used to study the effects of ion temperature anisotropy on GAM frequency and growth rate. We find that ion temperature anisotropy yields sensible modifications to both the GAM frequency and growth rate as both tend to increase with anisotropy and these results are strongly affected by the electron to ion temperature ratio

A systematic review of the adherence to home-practice meditation exercises in patients with chronic pain

Mindfulness-, compassion-, and acceptance-based (i.e., “third wave”) psychotherapies are effective for treating chronic pain conditions. Many of these programs require that patients engage in the systematic home practice of meditation experiences so they can develop meditation skills. This systematic review aimed at evaluating the frequency, duration, and effects of home practice in patients with chronic pain undergoing a “third wave” psychotherapy. A comprehensive database search for quantitative studies was conducted in PubMed, Embase, and Web of Sciences Core Collection; 31 studies fulfilled the inclusion criteria. The reviewed studies tended to indicate a pattern of moderately frequent practice (around four days/week), with very high variability in terms of time invested; most studies observed significant associations between the amount of practice and positive health outcomes. Mindfulness-Based Stress Reduction and Mindfulness-Based Cognitive Therapy were the most common interventions and presented low levels of adherence to home practice (39.6% of the recommended time). Some studies were conducted on samples of adolescents, who practiced very few minutes, and a few tested eHealth interventions with heterogeneous adherence levels. In conclusion, some adaptations may be required so that patients with chronic pain can engage more easily and, thus, effectively in home meditation practices

Nonlinear interaction of Alfv\'enic instabilities and turbulence via the modification of the equilibrium profiles

Nonlinear simulations of Alfv\'en modes (AM) driven by energetic particles (EP) in the presence of turbulence are performed with the gyrokinetic particle-in-cell code ORB5. The AMs carry a heat flux, and consequently they nonlinearly modify the plasma temperature profiles. The isolated effect of this modification on the dynamics of turbulence is studied, by means of electrostatic simulations. We find that turbulence is reduced when the profiles relaxed by the AM are used, with respect to the simulation where the unperturbed profiles are used. This is an example of indirect interaction of EPs and turbulence. First, an analytic magnetic equilibrium with circular concentric flux surfaces is considered as a simplified example for this study. Then, an application to an experimentally relevant case of ASDEX Upgrade is discussed