The Electric and Magnetic Field Instrument and Integrated Science (EMFISIS) investigation on the NASA Radiation Belt Storm Probes (now named the Van Allen Probes) mission provides key wave and very ...low frequency magnetic field measurements to understand radiation belt acceleration, loss, and transport. The key science objectives and the contribution that EMFISIS makes to providing measurements as well as theory and modeling are described. The key components of the instruments suite, both electronics and sensors, including key functional parameters, calibration, and performance, demonstrate that EMFISIS provides the needed measurements for the science of the RBSP mission. The EMFISIS operational modes and data products, along with online availability and data tools provide the radiation belt science community with one the most complete sets of data ever collected.
The aim of this study was to examine the effect of weight loss on health‐related quality of life (HRQL) in randomized controlled intervention trials (RCTs). MEDLINE, HealthStar and PsycINFO were ...searched. RCTs of any weight loss intervention and 20 HRQL instruments were examined. Contingency tables were constructed to examine the association between statistically significant weight loss and statistically significant HRQL improvement within five HRQL categories. In addition, Short Form‐36 (SF‐36) outcomes were pooled using random‐effects models. Fifty‐three trials were included. Seventeen studies reported statistically significant weight loss and HRQL improvement. No statistically significant associations between weight loss and HRQL improvement were found in any contingency table. Because of suboptimal endpoint reporting, quantitative data pooling could only be performed using 25% of SF‐36 trials in any one model. Significant improvements in physical health were found: mean difference 2.83 points, 95% CI 0.55–5.1, for the physical component score, and mean difference 6.81 points, 95% CI 2.99–10.63, for the physical functioning domain score. Conversely, no significant improvements in mental health were found. No significant association was found between weight loss and overall HRQL improvement. Weight loss may be associated with modest improvements in physical, but not mental, health.
Abstract
The general problem of an ocean on a rotating sphere is considered. The governing equations for an inviscid, incompressible fluid, written in spherical coordinates that are fixed at a point ...on the rotating Earth, together with the free surface and rigid bottom boundary conditions, are introduced. An exact solution of this system is presented; this describes a steady flow that is moving only in the azimuthal direction, with no variation in this direction. However, this azimuthal velocity component has an arbitrary variation with depth (i.e., radius), and so, for example, an Equatorial Undercurrent (EUC) can be accommodated. The pressure boundary condition at the free surface relates this pressure to the shape of the surface via a Bernoulli relation; this provides the constraint on the existence of a solution, although the restrictions are somewhat involved in spherical coordinates. To examine this constraint in more detail, the corresponding problems in model cylindrical coordinates (with the equator “straightened” to become a generator of the cylinder), and then in the tangent-plane version (with the
β
-plane approximation incorporated), are also written down. Both these possess similar exact solutions, with a Bernoulli condition that is more readily interpreted in terms of the choices available. Some simple examples of the surface pressure, and associated surface distortion, are presented. The relevance of these exact solutions to more complicated, and physically realistic, flow structures is briefly mentioned.
We propose a new, simple model - but one which has far-reaching consequences - to describe the interaction between waves that propagate across the Pacific Ocean and the Equatorial Undercurrent (EUC). ...This involves a detailed discussion of the full linear problem as it relates to the dynamic coupling between the surface waves and the internal waves on the thermocline. The result is a comprehensive description of the system close to the Equator, and how the structure of the EUC affects the wave properties; in particular, the analysis holds for arbitrary wavelengths and finite depths. Although the final expressions, for general wavelengths, are too cumbersome for direct interpretation, we are able to produce simple formulae for the speeds of the waves, and the attenuation factor between the two families of waves, for short, intermediate and long waves. Further, our results predict the appearance of critical layers under certain circumstances; by reverting to our original system of governing equations, we are able to derive the relevant nonlinear structure of the flow in these layers. Our results are in good agreement with the available field data.
This paper describes the science motivation, measurement objectives, performance requirements, detailed design, approach and implementation, and calibration of the four Hot Plasma Composition ...Analyzers (HPCA) for the Magnetospheric Multiscale mission. The HPCA is based entirely on electrostatic optics combining an electrostatic energy analyzer with a carbon-foil based time-of-flight analyzer. In order to fulfill mission requirements, the HPCA incorporates three unique technologies that give it very wide dynamic range capabilities essential to measuring minor ion species in the presence of extremely high proton fluxes found in the region of magnetopause reconnection. Dynamic range is controlled primarily by a novel radio frequency system analogous to an RF mass spectrometer. The RF, in combination with capabilities for high TOF event processing rates and high current micro-channel plates, ensures the dynamic range and sensitivity needed for accurate measurements of ion fluxes between ∼1 eV and 40 keV that are expected in the region of reconnection events. A third technology enhances mass resolution in the presence of high proton flux.
In order to calibrate the four HPCA instruments we have developed a unique ion calibration system. The system delivers a multi-species beam resolved to
M
/Δ
M
∼100 and current densities between 0.05 and 200 pA/cm
2
with a stability of ±5 %. The entire system is controlled by a dedicated computer synchronized with the HPCA ground support equipment. This approach results not only in accurate calibration but also in a comprehensive set of coordinated instrument and auxiliary data that makes analysis straightforward and ensures archival of all relevant data.
Abstract
The problem of flow moving purely in the azimuthal direction on a sphere is considered. An exact solution for an incompressible (constant density), inviscid fluid, which admits a velocity ...profile below the surface and along the surface, is constructed; this can be regarded as a model for the Antarctic Circumpolar Current (ACC). The new approach adopted here is to model the processes that produce the observed structure of the ACC by the introduction of a nonconservative body force. It is shown that if the body force is conservative, then the governing equations necessarily lead to profiles that are quite unrealistic. However, with a suitable choice of body force, which reverts to conservative outside the ACC, any velocity profile of any width can be constructed as an exact solution of the system. A fairly simple choice is made in this note in order to present some specific results: a profile on the surface that is zero outside the arc of the ACC, with a maximum at its center and decaying with depth. It is shown that the methods developed here can be used to produce ever more complicated profiles to correspond to different data. Indeed, the basic example that this study introduces can be regarded as one of the jets that compose the ACC, and the results allow for any number of such jets. Although only one velocity profile is described, it is emphasized that many different choices, motivated by direct velocity observations in specific regions, are possible within the model. In conclusion, a few comments are made outlining the way in which this exact solution can be embedded within more general and complete discussions of the ACC and its properties.
This review makes a case for describing many of the flows observed in our oceans, simply based on the Euler equation, with (piecewise) constant density and with suitable boundary conditions. The ...analyses start from the Euler and mass conservation equations, expressed in a rotating, spherical coordinate system (but the f-plane and β-plane approximations are also mentioned); five examples are discussed. For three of them, a suitable non-dimensionalization is introduced, and a single small parameter is identified in each case. These three examples lead straightforwardly and directly to new results for: waves on the Pacific Equatorial Undercurrent (EUC) with a thermocline (in the f-plane); a nonlinear, three-dimensional model for EUC-type flows (in the β-plane); and a detailed model for large gyres. The other two examples are exact solutions of the complete system: a flow which corresponds to the underlying structure of the Pacific EUC; and a flow based on the necessary requirement to use a non-conservative body force, which produces the type of flow observed in the Antarctic Circumpolar Current. (All these examples have been discussed in detail in the references cited.) This review concludes with a few comments on how these solutions can be extended and expanded.
This article is part of the theme issue ‘Nonlinear water waves’.
We revisit the classical problem of the behaviour of the wind in the steady atmospheric Ekman layer. We show, for
general
variable eddy viscosities, that in the Northern Hemisphere the time-averaged ...ageostrophic wind profile
always
decays in magnitude and turns clockwise with increasing height. This general result is new; all previous work is based on a few explicit, special examples. As part of the development, we present two ways of formulating the problem, one of which is a novel approach (making use of a transformation to polar coordinates) that helps to explain the complex nature of these flows. The two formulations are supported by several examples that show, for instance, how the deflection angle can be other than the familiar
45
∘
. These results can be used as the basis for testing, and developing, various models for the height variation of eddy viscosity.
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