Shocklike soliton because of an impinge of protons and electrons solar particles with Venus ionosphere

This paper introduces an investigation of shocklike soliton or small amplitude Double Layers (DLs) in a collisionless plasma, consisting of positive and negative ions, nonthermal electrons, as well as solar wind streaming protons and electrons. Gardner equation is derived and its shocklike soliton solution is obtained. The model is employed to recognize a possible nonlinear wave at Venus ionosphere. The results indicate that the number densities and velocities of the streaming particles play crucial role to determine the polarity and characteristic features (amplitude and width) of the shocklike soliton waves. An electron streaming speed modifies a negative shocklike wave profile, while an ion streaming speed modulates a positive shocklike wave characteristic.     

Improving the orbits of GPS block IIA satellites during eclipse seasons

During Sun-Earth eclipse seasons, GPS-IIA satellites perform noon, shadow and post-shadow yaw maneuvers. If the yaw maneuvers are not properly taken into account in the orbit determination process, two problems appear: (1) the observations residuals increase since the modeled position of the satellite’s navigation antenna differs from the true position, and (2) the non-conservative forces like solar radiation pressure or Earth radiation pressure are mismodeled due to the wrong orientation of the satellite’s surfaces in space.     

The Dawn Framing Camera

The Framing Camera (FC) is the German contribution to the Dawn mission. The camera will map 4 Vesta and 1 Ceres through a clear filter and 7 band-pass filters covering the wavelengths from the visible to the near-IR. The camera will allow the determination of the physical parameters of the asteroids, the reconstruction of their global shape as well as local topography and surface geomorphology, and provide information on composition via surface reflectance characteristics. The camera will also serve for orbit navigation. The resolution of the Framing Camera will be up to 12 m per pixel in low altitude mapping orbit at Vesta (62 m per pixel at Ceres), at an angular resolution of 93.7 ??rad?px^?1. The instrument uses a reclosable front door to protect the optical system and a filter-wheel mechanism to select the band-pass for observation. The detector data is read out and processed by a data processing unit. A power converter unit supplies all required power rails for operation and thermal maintenance. For redundancy reasons, two identical cameras were provided, both located side by side on the +Z-deck of the spacecraft. Each camera has a mass of 5.5 kg.     

GRB host galaxies: An unbiased sample

We describe the current status and recent results from our Swift/VLT legacy survey, a VLT Large Programme aimed at characterizing the host galaxies of a homogeneously selected sub-sample of Swift   GRBs. The immediate goals are to determine the host luminosity function, study the effects of reddening, determine the fraction of Lyα$\mathrm{Ly}\mathrm{\alpha }$ emitters in the hosts, and obtain redshifts for targets without a reported one. The main effort so far has been the definition of a very carefully selected sample, obeying strict and well-defined criteria: 68 targets in total. Among the preliminary results is a large optical detection rate, the lack of extremely red objects (only one possible case in the sample) and an update of the Swift   GRB redshift distribution with 〈z〉∼2.0$〈z〉\sim 2.0$.     

No correlation between multilamellar bodies in the inner ear and further organs of mutant (backstroke, bks) and wildtype zebrafish embryos.

The origin of the proteinacious matrix of the inner ear stones (otoliths) of vertebrates has not yet been clarified. Using the backstroke mutant (bks) of the zebrafish Danio rerio, which is characterized by a complete lack of otoliths, we searched for possibly missing or aberrant structural components within the macular epithelia of the inner ears of embryos on the ultrastructural level. Numerous multilamellar bodies (MLBs) were found. The MLBs were, however, not restricted to the inner ears of mutants but were also found in wildtype individuals and in further organs such as brain and liver. MLBs have hitherto never been described from the inner ear of fish and are generally estimated to be rare structures. Their occurrence in fish liver can, however, be induced by using particular chemical substances, which seem to effect adaptive compensatory processes on the cellular level. Such a chemical treatment also affects the ultrastructure of further organelles. Since the occurrence of MLBs in the liver of zebrafish was not accompanied by an alteration of the morphology of other organelles, their occurrence seems not to be due to environmental stress. The findings indicate that the MLBs cannot be correlated with bks-inherent features as well as with missing otolith development/growth. Since the occurrence of MLBs was independent from the developmental stage of a specimen and its overall tissue preservation, it can moreover be excluded that these MLBs merely represent fixation artifacts. Their presence more likely indicates cellular remodelling processes of hitherto unknown significance.     

Two-valued frequency-coded waveforms with favorable periodic autocorrelation

There are known phase-coded (two-valued or polyphase) CW radar signals that exhibit perfect periodic autocorrelation function (PACF). A PACF is perfect when all its out-of-phase autocorrelation values are identically equal to zero. This paper investigates periodic, two-valued, frequency-coded signals. While none could be found with perfect PACF, we present examples with nearly perfect PACF. Their relationship to binary phase-coded signals is also considered. These signals should be attractive for CW radars because of their simple implementation, clean spectrum, and the favorable range response of their matched receiver.     

ICMEs in the Inner Heliosphere: Origin, Evolution and Propagation Effects

This report assesses the current status of research relating the origin at the Sun, the evolution through the inner heliosphere and the effects on the inner heliosphere of the interplanetary counterparts of coronal mass ejections (ICMEs). The signatures of ICMEs measured by in-situ spacecraft are determined both by the physical processes associated with their origin in the low corona, as observed by space-borne coronagraphs, and by the physical processes occurring as the ICMEs propagate out through the inner heliosphere, interacting with the ambient solar wind. The solar and in-situ observations are discussed as are efforts to model the evolution of ICMEs from the Sun out to 1 AU.     

Influence of estimation errors on wayfinding-decisions in unknown street networks – analyzing the least-angle strategy

The least-angle strategy is a common wayfinding method that can be applied in unknown environments if the target direction is known. The strategy is based on the navigator's heuristic to select the street segment at an intersection which is most in line with the target direction. To use this strategy, the navigator needs to know the angles between the target direction and the street segments leading out from the intersection. If the direct view to the target is blocked and the target vector cannot be perceived, the target direction that is needed for the decision process is based on the agent's believed position and orientation (estimated through path integration). The agent's believed position and target direction are distorted by human errors in estimation of distances and directions, mainly affecting the path integration process. In this paper we examine how human estimation errors of distance and rotation influence the decision behavior in the wayfinding process in an unknown street environment. To demonstrate the geometrical consequences for a specific test case, we use a simulated software agent which navigates in a simulated street environment.     

World-wide radiation dosage calculations for air crew members.

A greatly improved version of the computer program to calculate radiation dosage to air crew members is now available. Designated CARI-6, this program incorporates an updated geomagnetic cutoff rigidity model and a revision of the primary cosmic ray spectrum based on recent work by Gaisser and Stanev (1998). We believe CARI-6 provides the most accurate available method for calculating the radiation dosage to air crew members. The program is now utilized by airline companies around the world and provides unification for subsequent world-wide studies on the effects of natural radiation on aircrew members.     

I: PRECISE ORBIT DETERMINATION AND GRAVITY FIELD MODELLING: Strategies for Precise Orbit Determination of Low Earth Orbiters Using the GPS

Considerable experience accumulated during the past decade in strategies for processing GPS data from ground-based geodetic receivers. First experience on the use of GPS observations from spaceborne receivers for orbit determination of satellites on low altitude orbits was gained with the launch of TOPEX/POSEIDON ten years ago. The launch of the CHAMP satellite in July 2000 stimulated a number of activities worldwide on improving the strategies and algorithms for orbit determination for Low Earth Orbiters (LEOs) using the GPS. Similar strategies as for ground-based receivers are applied to data from spaceborne GPS receivers to determine high precision orbits. Zero- and double-differencing techniques are applied to obtain kinematic and/or reduced-dynamic orbits with an accuracy which is today at the decimeter level. Further developments in modeling and processing strategies will continuously improve the quality of GPS-derived LEO orbits in the near future. A significant improvement can be expected from fixing double-difference phase ambiguities to integer numbers. Particular studies focus on the impact of a combined processing of LEO and GPS orbits on the quality of orbits and the reference frame realization. This revised version was published online in August 2006 with corrections to the Cover Date.