77 research outputs found

    The magnetic field of Mars estimated from the data of plasma measurements by Soviet artificial satellites of Mars

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    The dimensions of the obstacle forming the shock wave of Mars are estimated by use of electron trap data from Mars 2, 3, and 5. The mean altitude of the obstacle at the subsolar point can be convincingly explained if the obstacle is the magnetosphere of Mars. On the assumption that Mars has its own dipole magnetic field, the magnetic moment of Mars is estimated, Mm approximately equal to 2 x 10 to the twenty second power gs x cubic cu

    Magnetic field and plasma inside and outside of the Martian magnetosphere

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    Simultaneous magnetic and plasma measurements, carried out by wide angle plasma detectors in the Mars environment, are compared in order to identify regions with significantly different physical properties. Magnetograms and ion spectra indicate changes in the magnetopause and magnetosphere of Mars that are associated with the dynamic pressure effect of the solar wind

    Detection of a new “chemical” boundary at comet Halley

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95342/1/grl3208.pd

    Linking Adult Reproduction and Larval Density of Invasive Carp in a Large River

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    Identifying how temporal variation in the environment affects reproductive success of invasive alien species will aid in predicting future establishment and tracking dynamics of established populations. Asian carp Hypophthalmichthys spp. have become a nuisance in recent years in the Mississippi River basin. Their populations are apparently expanding, indicating favorable conditions for reproduction. During 2004 and 2005, we quantified mean density of Asian carp larvae, mean monthly gonadosomatic index (GSI) of adult males and females, and number of eggs within mature females in the lower Illinois River, a major tributary of the Mississippi River. A flood (water velocity ≄ 0.7 m/s) and drought (\u3c0.2 m/s) occurred during apparent spawning in 2004 and 2005, respectively. During 2004, Asian carp larvae were found during 32% of sampling weeks; mean GSI and fecundity were relatively low for adults, probably reflecting partially spawned individuals and perhaps low reproductive investment. During the drought of 2005, larval stages were present during only one (5%) of the sampling weeks, whereas mean GSI and fecundity of adults were high through summer. Females resorbed their eggs instead of spawning during this year. Spawning conditions during low water periods appear to be unsuitable for Asian carps, inhibiting adult spawning and yielding few larvae. Spawning conditions during 2004 were better but still yielded low densities of larvae relative to native fishes. Reproduction in the lower Illinois River appears to be linked to river flow and its impact on adult spawning decisions, but conditions for strong year-class production (i.e., high larval densities) may be rarer than previously expected

    Energy distribution of electrons with E < 800 eV in the areomagnetosphere

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    The electron distribution functions measured in the neighborhood of Mars by means of the Hyperbolic Retarding Potential Analyzer (HARP) carried aboard the Phobos 2 spacecraft are presented. The measurements were carried out over an energy/charge (E/q) from ~0.3 eV to ~800 eV in eight independent angular sectors ~ 20[deg] x 10[deg] covering the FOV ~ 180[deg] in the X-Z plane in the antisolar directions.The total intensity and energy distribution function of electrons downstream of the bow shock clearly differ from those in the undisturbed solar wind. The electron fluxes are significantly increased and the energy distribution of electrons in the magnetosheath was found to be characterized by the double-peaked structure. The high energy fluxes often exceed the flux values for the low energy peak.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29560/1/0000648.pd
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