Explore the vast range of titles available.

The evolution of structures associated with mirror modes during their flow in the Earth's magnetosheath is studied. The fact that the related magnetic fluctuations can take distinct shapes, from deep holes to high peaks, has been assessed in previous works on the observational, modeling and numerical points of view. In this paper we present an analytical model for the flow lines and velocity magnitude inside the magnetosheath. This model is used to interpret almost 10 years of Cluster observations of mirror structures: by back tracking each isolated observation to the shock, the \"age\", or flow time, of these structures is determined together with the geometry of the shock. Using this flow time the evolutionary path of the structures may be studied with respect to different quantities: the distance to mirror threshold, the amplitude of mirror fluctuations and the skewness of the magnetic amplitude distribution as a marker of the shape of the structures. These behaviours are confronted to numerical simulations which confirm the dynamical perspective gained from the association of the statistical analysis and the analytical model: magnetic peaks are mostly formed just behind the shock and are quickly overwhelmed by magnetic holes as the plasma conditions get more mirror stable. The amplitude of the fluctuations are found to saturate before the skewness vanishes, i.e. when both structures quantitatively balance each other, which typically occurs after a flow time of 100–200 s in the Earth's magnetosheath. Comparison with other astrophysical contexts is discussed.

BACKGROUND AND AIMS: Genome size and chromosome numbers are important cytological characters that significantly influence various organismal traits. However, geographical representation of these data is seriously unbalanced, with tropical and subtropical regions being largely neglected. In the present study, an investigation was made of chromosomal and genome size variation in the majority of Curcuma species from the Indian subcontinent, and an assessment was made of the value of these data for taxonomic purposes. METHODS: Genome size of 161 homogeneously cultivated plant samples classified into 51 taxonomic entities was determined by propidium iodide flow cytometry. Chromosome numbers were counted in actively growing root tips using conventional rapid squash techniques. KEY RESULTS: Six different chromosome counts (2n = 22, 42, 63, >70, 77 and 105) were found, the last two representing new generic records. The 2C-values varied from 1·66 pg in C. vamana to 4·76 pg in C. oligantha, representing a 2·87-fold range. Three groups of taxa with significantly different homoploid genome sizes (Cx-values) and distinct geographical distribution were identified. Five species exhibited intraspecific variation in nuclear DNA content, reaching up to 15·1 % in cultivated C. longa. Chromosome counts and genome sizes of three Curcuma-like species (Hitchenia caulina, Kaempferia scaposa and Paracautleya bhatii) corresponded well with typical hexaploid (2n = 6x = 42) Curcuma spp. CONCLUSIONS: The basic chromosome number in the majority of Indian taxa (belonging to subgenus Curcuma) is x = 7; published counts correspond to 6x, 9x, 11x, 12x and 15x ploidy levels. Only a few species-specific C-values were found, but karyological and/or flow cytometric data may support taxonomic decisions in some species alliances with morphological similarities. Close evolutionary relationships among some cytotypes are suggested based on the similarity in homoploid genome sizes and geographical grouping. A new species combination, Curcuma scaposa (Nimmo) Škorničk. & M. Sabu, comb. nov., is proposed.

Estimating the temperature of solar wind particles and their anisotropies is particularly important for understanding the origin of their deviations from thermal equilibrium and the effects this has. In the absence of energetic events, the velocity distribution of electrons reveals a dual structure with a thermal (Maxwellian) core and a suprathermal (kappa) halo. This article presents a detailed observational analysis of these two components, providing estimations of their temperatures and temperature anisotropies, and decoding any potential interdependence that their properties may indicate. The dataset used in this study includes more than 120 000 of the distributions measured by three missions in the ecliptic within an extended range of heliocentric distances from 0.3 to over 4 AU. The core temperature is found to decrease with the radial distance, while the halo temperature slightly increases, clarifying an apparent contradiction in previous observational analyses and providing valuable clues about the temperature of the kappa-distributed populations. For low values of the power-index kappa, these two components manifest a clear tendency to deviate from isotropy in the same direction, which seems to confirm the existence of mechanisms with similar effects on both components, e.g. , the solar wind expansion, or the particle heating by the fluctuations. However, the existence of plasma states with anticorrelated anisotropies of the core and halo populations and the increase in their number for high values of the power-index kappa suggest a dynamic interplay of these components, mediated, most probably, by the anisotropy-driven instabilities.

On July 24, 2003, when the Cluster 4 satellite crossed the magnetic equator at about 4.5 RE radial distance on the dusk side (∼15 MLT), whistler wave emissions were observed below the local electron gyrofrequency (fce) in two bands, one band above one‐half the gyrofrequency (0.5fce) and the other band below 0.5fce. A careful analysis of the wave emissions for this event has shown that Cluster 4 passed through the wave source region. Simultaneous electron particle data from the PEACE instrument in the generation region indicated the presence of a mid‐energy electron population (∼100 s of eV) that had a highly anisotropic temperature distribution with the perpendicular temperature 10 times the parallel temperature. To understand this somewhat rare event in which the satellite passed directly through the wave generation region and in which a free energy source (i.e., temperature anisotropy) was readily identified, a linear theory and particle in cell simulation study has been carried out to elucidate the physics of the wave generation, wave‐particle interactions, and energy redistribution. The theoretical results show that for this event the anisotropic electron distribution can linearly excite obliquely propagating whistler mode waves in the upper frequency band, i.e., above 0.5fce. Simulation results show that in addition to the upper band emissions, nonlinear wave‐wave coupling excites waves in the lower frequency band, i.e., below 0.5fce. The instability saturates primarily by a decrease in the temperature anisotropy of the mid‐energy electrons, but also by heating of the cold electron population. The resulting wave‐particle interactions lead to the formation of a high‐energy plateau on the parallel component of the warm electron velocity distribution. The theoretical results for the saturation time scale indicate that the observed anisotropic electron distribution must be refreshed in less than 0.1 s allowing the anisotropy to be detected by the electron particle instrument, which takes several seconds to produce a distribution.

A model for the nonlinear dynamics of mirror modes near the instability threshold is presented. By matching the quasi‐linear theory for the space‐averaged distribution function with a reductive perturbative description of the mirror modes, the model reproduces the early‐time flattening of the distribution function and the development of magnetic humps from an initial noise, in agreement with Vlasov‐Maxwell numerical simulations. It suggests a possible mechanism at the origin of the mirror structures observed in planetary magnetosheaths and in the solar wind.

On 29 April 1998, a coronal mass ejection (CME) was emitted from the Sun that had a significant impact at Earth. The terrestrial magnetosphere became more electrically active during the storm passage. Less explored is the effect of such a storm on an exposed rocky body like our Moon. The solar‐storm/lunar atmosphere modeling effort (SSLAM) brings together surface interactions, exosphere, plasma, and surface charging models all run with a common driver – the solar storm and CME passage occurring from 1 to 4 May 1998. We present herein an expanded discussion on the solar driver during the 1–4 May 1998 period that included the passage of an intense coronal mass ejection (CME) that had >10 times the solar wind density and had a compositional component of He++ that exceeded 20%. During this time, the plasma mass flux to the exposed lunar surface increased by over 20 times compared to the nominal solar wind, to a value near 10−13 kg/m2‐s. Over a two day CME passage by the Moon, this amount approaches 300 tons of added mass to the Moon in the form of individual proton and helium ions. Such an increase in ion flux should have a profound impact on sputtering loss rates from the surface, since this process scales as the mass, energy, and charge state of the incident ion. Associated loss processes were addressed by SSLAM and will be discussed herein. Key Points The energy in solar storms has a direct impact on exposed near‐airless bodies SSLAM study designed to understand the impact of space weather on exposed rocky bodies

NASA’s two spacecraft ARTEMIS mission will address both heliospheric and planetary research questions, first while in orbit about the Earth with the Moon and subsequently while in orbit about the Moon. Heliospheric topics include the structure of the Earth’s magnetotail; reconnection, particle acceleration, and turbulence in the Earth’s magnetosphere, at the bow shock, and in the solar wind; and the formation and structure of the lunar wake. Planetary topics include the lunar exosphere and its relationship to the composition of the lunar surface, the effects of electric fields on dust in the exosphere, internal structure of the Moon, and the lunar crustal magnetic field. This paper describes the expected contributions of ARTEMIS to these baseline scientific objectives.

The paper is focused on the uncertainty estimation of the mean isobaric and isochoric specific heat capacity calculation. The differences in the data among the individual sources for the technical calculation are presented in the first part of the paper. These differences are discussed in this paper. Research of scientific work with listed values of measurement uncertainties has been carried out in the second part of the paper. Furthermore, mathematical models were calculated which describe the dependence of the specific heat capacities and temperature. The maximal error models were carried out. Two approaches were used for the calculation of the mean specific heat capacity. The first approach is the calculation with help of integration of the function which describes the dependence of the specific heat capacity and temperature. The second approach is the calculation of a simple arithmetic mean of the specific heat capacity related to the maximal and minimal value of the temperature interval. The conclusion of the work shows that the time-effective second way is applicable in the case of a narrow temperature range. A value of 5.5% (Δt= 200 K) was reached for the relative uncertainty. This is a similar value to that in the case of using the first way.

X‐rays can be generated by charge exchange between highly‐charged heavy solar wind ions and neutrals. Previously, simulations have only been performed for X‐ray emission due to solar wind charge exchange (SWCX) with geocoronal and interstellar neutrals. However, X‐rays can also be generated by SWCX with the Moon's tenuous exosphere, which should be detectable by an imaging X‐ray instrument located on the Moon. In addition, lunar‐based observations of X‐ray emission originating from Earth's magnetosheath will be able to provide information on the dynamic response of the bow shock and magnetopause to solar wind variations. Furthermore, X‐ray emissions from SWCX within the heliosphere constitute part of the soft X‐ray background (SXRB) emission, competing with emissions originating from outside the solar system. Lunar observations of soft X‐rays will give additional information about these charge exchange processes and be critical in removing the heliospheric component of the SXRB.

The Radio & Plasma Wave Investigation (RPWI) onboard the ESA JUpiter ICy moons Explorer (JUICE) is described in detail. The RPWI provides an elaborate set of state-of-the-art electromagnetic fields and cold plasma instrumentation, including active sounding with the mutual impedance and Langmuir probe sweep techniques, where several different types of sensors will sample the thermal plasma properties, including electron and ion densities, electron temperature, plasma drift speed, the near DC electric fields, and electric and magnetic signals from various types of phenomena, e.g., radio and plasma waves, electrostatic acceleration structures, induction fields etc. A full wave vector, waveform, polarization, and Poynting flux determination will be achieved. RPWI will enable characterization of the Jovian radio emissions (including goniopolarimetry) up to 45 MHz, has the capability to carry out passive radio sounding of the ionospheric densities of icy moons and employ passive sub-surface radar measurements of the icy crust of these moons. RPWI can also detect micrometeorite impacts, estimate dust charging, monitor the spacecraft potential as well as the integrated EUV flux. The sensors consist of four 10 cm diameter Langmuir probes each mounted on the tip of 3 m long booms, a triaxial search coil magnetometer and a triaxial radio antenna system both mounted on the 10.6 m long MAG boom, each with radiation resistant pre-amplifiers near the sensors. There are three receiver boards, two Digital Processing Units (DPU) and two Low Voltage Power Supply (LVPS) boards in a box within a radiation vault at the centre of the JUICE spacecraft. Together, the integrated RPWI system can carry out an ambitious planetary science investigation in and around the Galilean icy moons and the Jovian space environment. Some of the most important science objectives and instrument capabilities are described here. RPWI focuses, apart from cold plasma studies, on the understanding of how, through electrodynamic and electromagnetic coupling, the momentum and energy transfer occur with the icy Galilean moons, their surfaces and salty conductive sub-surface oceans. The RPWI instrument is planned to be operational during most of the JUICE mission, during the cruise phase, in the Jovian magnetosphere, during the icy moon flybys, and in particular Ganymede orbit, and may deliver data from the near surface during the final crash orbit.