An Evening Sector Ps 6 - Omega Band Event

Article draft. Author list indicative and roughly corresponds to amount of contribution to the article to date.Abstract. Ps 6 magnetic disturbances and associated optical forms known as omega bands are usually associated with the morning sector. Some evidence for similar phenomenology in the evening sector has been presented by Solovyev et al. (1999). We confirm and extend those results with high time resolution magnetic and imaging observations from Athabasca University Geophysical Observatory for an event that took place on July 27, 2003, along with conjugate hemisphere imaging from the Polar spacecraft. The observed signatures indicate sunward drift (westward in the evening sector). Magnetic perturbations feature negative Y and transitional Z indicating westward passage of poleward equivalent currents overhead. As has been suggested by Connors et al. (2003) to be often the case for morning sector Ps 6/omega bands, initiation of the evening sector event coincided with substorm onset. From optical and magnetic data we obtain consistent results for the drift rate of the forms, which changed during the event. An inner magnetospheric source is suggested, with triggering of the onset by an increase in solar wind speed

Impact of CIR Storms on Thermosphere Density Variability during the Solar Minimum of 2008

The solar minimum of 2008 was exceptionally quiet, with sunspot numbers at their lowest in 75 years. During this unique solar minimum epoch, however, solar wind high - speed streams emanating from near-equatorial coronal holes occurred frequently and were the primary contributor to the recurrent geomagnetic activity at Earth. These conditions enabled the isolation of forcing by geomagnetic activity on the preconditioned solar minimum state of the upper atmosphere caused by Corotating Interaction Regions (CIRs). Thermosphere density observations around 400 km from the CHAMP satellite are used to study the thermosphere density response to solar wind high - speed streams/CIRs. Superposed epoch results show that thermosphere density responds to high - speed streams globally, and the density at 400 km changes by 75% on average. The relative changes of neutral density are comparable at different latitudes, although its variability is largest at high latitudes. In addition, the response of thermosphere density to high - speed streams is larger at night than in daytime, indicating the preconditioning effect of the thermosphere response to storms. Finally, the thermosphere density variations at the periods of 9 and 13.5 days associated with CIRs are linked to the spatial distribution of low - middle latitude coronal holes on the basis of the EUVI observations from the STEREO.Comment: Solar Physics, accepted, April 2010, and the final version of this paper will appear in the website of Solar Physics soon

Automated Regional Modelling (ARM) for characterization of the substorm current wedge

Poster, ICS-9, Seggau, Austria, May 2008Some characteristics of substorms may be determined through use of an electrojet forward modelling approach. These include the amplitude of cross-meridian electric current (0.2 to 1 MA typically), timescales (about 20 minutes to peak current and poleward extension), and amount of poleward motion (several degrees). An increase in the number of magnetic stations deployed in North America makes use of a full substorm current wedge system possible, reproducing well the perturbations observed both in the auroral zone and at subauroral stations. This provides good characterization not only of the aforementioned parameters, but also of the substorm longitudinal parameters including the central meridian. In principle, extension of near-Earth field-aligned currents into space is possible based on inversion results and field models. In practice, comparison with data from spacecraft such as THEMIS is complicated by processes in space such as plasma sheet changes at substorm onse

MESSENGER and Mariner 10 flyby observations of magnetotail structure and dynamics at Mercury

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94896/1/jgra21525.pd

Activation of latent human GDF9 by a single residue change (Gly(391)Arg) in the mature domain

Growth differentiation factor 9 (GDF9) controls granulosa cell growth and differentiation during early ovarian folliculogenesis and regulates cumulus cell function and ovulation rate in the later stages of this process. Similar to other TGF-β superfamily ligands, GDF9 is secreted from the oocyte in a noncovalent complex with its prodomain. In this study, we show that prodomain interactions differentially regulate the activity of GDF9 across species, such that murine (m) GDF9 is secreted in an active form, whereas human (h) GDF9 is latent. To understand this distinction, we used site-directed mutagenesis to introduce nonconserved mGDF9 residues into the pro- and mature domains of hGDF9. Activity-based screens of the resultant mutants indicated that a single mature domain residue (Gly³⁹¹) confers latency to hGDF9. Gly³⁹¹ forms part of the type I receptor binding site on hGDF9, and this residue is present in all species except mouse, rat, hamster, galago, and possum, in which it is substituted with an arginine. In an adrenocortical cell luciferase assay, hGDF9 (Gly³⁹¹Arg) had similar activity to mGDF9 (EC₅₀ 55 ng/ml vs. 28 ng/ml, respectively), whereas wild-type hGDF9 was inactive. hGDF9 (Gly³⁹¹Arg) was also a potent stimulator of murine granulosa cell proliferation (EC₅₀ 52 ng/ml). An arginine at position 391 increases the affinity of GDF9 for its signaling receptors, enabling it to be secreted in an active form. This important species difference in the activation status of GDF9 may contribute to the variation observed in follicular development, ovulation rate, and fecundity between mammals.Courtney M. Simpson, Peter G. Stanton, Kelly L. Walton, Karen L. Chan, Lesley J. Ritter, Robert B. Gilchrist, and Craig A. Harriso

Mesoscale phenomena and their contribution to the global response: a focus on the magnetotail transition region and magnetosphere-ionosphere coupling

An important question that is being increasingly studied across subdisciplines of Heliophysics is “how do mesoscale phenomena contribute to the global response of the system?” This review paper focuses on this question within two specific but interlinked regions in Near-Earth space: the magnetotail’s transition region to the inner magnetosphere and the ionosphere. There is a concerted effort within the Geospace Environment Modeling (GEM) community to understand the degree to which mesoscale transport in the magnetotail contributes to the global dynamics of magnetic flux transport and dipolarization, particle transport and injections contributing to the storm-time ring current development, and the substorm current wedge. Because the magnetosphere-ionosphere is a tightly coupled system, it is also important to understand how mesoscale transport in the magnetotail impacts auroral precipitation and the global ionospheric system response. Groups within the Coupling, Energetics and Dynamics of Atmospheric Regions Program (CEDAR) community have also been studying how the ionosphere-thermosphere responds to these mesoscale drivers. These specific open questions are part of a larger need to better characterize and quantify mesoscale “messengers” or “conduits” of information—magnetic flux, particle flux, current, and energy—which are key to understanding the global system. After reviewing recent progress and open questions, we suggest datasets that, if developed in the future, will help answer these questions

ISSN exercise & sport nutrition review: research & recommendations

Sports nutrition is a constantly evolving field with hundreds of research papers published annually. For this reason, keeping up to date with the literature is often difficult. This paper is a five year update of the sports nutrition review article published as the lead paper to launch the JISSN in 2004 and presents a well-referenced overview of the current state of the science related to how to optimize training and athletic performance through nutrition. More specifically, this paper provides an overview of: 1.) The definitional category of ergogenic aids and dietary supplements; 2.) How dietary supplements are legally regulated; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of the ergogenic value of nutrition and dietary supplementation in regards to weight gain, weight loss, and performance enhancement. Our hope is that ISSN members and individuals interested in sports nutrition find this review useful in their daily practice and consultation with their clients

The Solar Wind and Geomagnetic Activity as a Function of Time Relative to Corotating Interaction Regions

Corotating interaction regions during the declining phase of the solar cycle are the cause of recurrent geomagnetic storms and are responsible for the generation of high fluxes of relativistic electrons. These regions are produced by the collision of a high-speed stream of solar wind with a slow-speed stream. The interface between the two streams is easily identified with plasma and field data from a solar wind monitor upstream of the Earth. The properties of the solar wind and interplanetary magnetic field are systematic functions of time relative to the stream interface. Consequently the coupling of the solar wind to the Earth's magnetosphere produces a predictable sequence of events. Because the streams persist for many solar rotations it should be possible to use terrestrial observations of past magnetic activity to predict future activity. Also the high-speed streams are produced by large unipolar magnetic regions on the Sun so that empirical models can be used to predict the velocity profile of a stream expected at the Earth. In either case knowledge of the statistical properties of the solar wind and geomagnetic activity as a function of time relative to a stream interface provides the basis for medium term forecasting of geomagnetic activity. In this report we use lists of stream interfaces identified in solar wind data during the years 1995 and 2004 to develop probability distribution functions for a variety of different variables as a function of time relative to the interface. The results are presented as temporal profiles of the quartiles of the cumulative probability distributions of these variables. We demonstrate that the storms produced by these interaction regions are generally very weak. Despite this the fluxes of relativistic electrons produced during those storms are the highest seen in the solar cycle. We attribute this to the specific sequence of events produced by the organization of the solar wind relative to the stream interfaces. We also show that there are large quantitative differences in various parameters between the two cycles

Interpretation of Automated Forward Modeling Parameters for Sawtooth Events and Substorms

Automated Forward Modeling (AFM) is an inversion technique based on magnetic data alone, which can indicate physical parameters associated with electrojets. From perturbations along a meridian, the total electric current crossing the meridian may be determined, as well as the latitudes between which it flowed. The technique is based on nonlinear optimization of the parameters of a forward model. It is possible to compare model output to the original input to ensure that the routine has functioned well and that output parameters are reliable and presumably have physical meaning. Characteristic behaviors of substorms are readily seen in modeling output: the current strengthens rapidly and considerably at an expansive phase onset, following a growth phase during which the electrojet borders move equatorward, usually with some strengthening of current. At onset the poleward border is often seen to move poleward rapidly. Poleward border activity may be noted then and also at other times. After an onset, the recovery phase is often marked by a retreat of the equatorward border, indicating the well-known shrinkage of the auroral oval then. These complete cycles of activity are absent in sawtooth events. Our output parameters can be diagnostic of onsets and useful in determining their location and role in sawtooth events. These have many of the characteristics of expansive phase onsets, but maximum poleward expansion of the poleward border is followed by equatorward movement reminiscent of a growth phase. Since this is correlated with the interplanetary magnetic field remaining southward, the difference from common expansive phase phenomenology may simply be the lack of a recovery phase