GNSS-R concept extended by a fine orbit tuning

Small changes in semimajor axis of the orbits selected for the GNSS-R [R as Reflectometry] satellites, so-called fine orbit tuning, known from the ESA’s Gravity and steady-state Ocean Circulation Explorer mission, can dramatically increase the number of nadir and off-nadir reflecting points and, in turn, can enhance the capability of the concept of bistatic altimetry (GNSS Reflectometry) without additional costs. The application of our suggestion is feasible for a satellite which will be equipped by thrusters for the orbit keeping. During the mission lifetime several orbit tunings are feasible, just to transfer from one to another orbit. Then we can study short-periodic or longer-periodic features, according to scientific goals defined for the mission. The shortest cycles (few days), corresponding to the required revisit time (defined by ESA), may be subcycles of much longer cycles (repeat periods).     

Solar wind turbulence during the solar cycle deduced from Galileo coronal radio-sounding experiments

Seven coronal radio-sounding campaigns were carried out during the active lifetime of the Galileo spacecraft in the years 1994–2002. The observational data analyzed in the present work are S-band frequency fluctuation measurements recorded during the solar conjunctions at different phases of solar activity cycle #23, specifically: periods near solar maximum (three conjunctions), near solar minimum (three conjunctions) and during the ascending phase (one conjunction). These data are all applicable to low heliographic latitudes, i.e. to the slow solar wind. The rms frequency fluctuation and power-law index of the frequency fluctuation temporal spectra are determined as a function of heliocentric distance. The turbulence power spectrum tends to be flatter inside ca. 20 solar radii during all phases of the solar cycle. This coincides with a transition in the flow from the inner acceleration region to the outer region of constant velocity. The radial falloff rate and absolute level of the rms frequency fluctuation are essentially invariant over the solar cycle.     

Height of shock formation in the solar corona inferred from observations of type II radio bursts and coronal mass ejections

Employing coronagraphic and EUV observations close to the solar surface made by the Solar Terrestrial Relations Observatory (STEREO) mission, we determined the heliocentric distance of coronal mass ejections (CMEs) at the starting time of associated metric type II bursts. We used the wave diameter and leading edge methods and measured the CME heights for a set of 32 metric type II bursts from solar cycle 24. We minimized the projection effects by making the measurements from a view that is roughly orthogonal to the direction of the ejection. We also chose image frames close to the onset times of the type II bursts, so no extrapolation was necessary. We found that the CMEs were located in the heliocentric distance range from 1.20 to 1.93 solar radii (Rs), with mean and median values of 1.43 and 1.38 Rs, respectively. We conclusively find that the shock formation can occur at heights substantially below 1.5 Rs. In a few cases, the CME height at type II onset was close to 2 Rs. In these cases, the starting frequency of the type II bursts was very low, in the range 25–40 MHz, which confirms that the shock can also form at larger heights. The starting frequencies of metric type II bursts have a weak correlation with the measured CME/shock heights and are consistent with the rapid decline of density with height in the inner corona.     

Neutron stars: Classification and evolution

The general aproach is considered which describs the evolution of neutron stars in terms of their interaction with surrounding matter. All possible states of neutron stars are classified from this point of view. Classification and evolution of binaries contaning neutron stars are also considered.     

The local interstellar medium viewed through pickup ions, recent results and future perspectives

Over the last 10 years the experimental basis for the study of the very local interstellar medium (VLISM) has been substantially broadened by the direct detection of pickup ions and of neutral helium. The strength of these methods lies in the local measurement of the particles. By scanning the gravitational focusing cone of the interstellar wind, a consistent set of interstellar helium parameters, neutral density, temperature and relative velocity, has been derived. However, the accuracy of these parameters is still hampered by uncertainties in some of the crucial ionization rates and in the pickup ion transport. Recent observations have shown that the scattering mean free path of pickup ions is comparable with the large scale variation of the interplanetary magnetic field (IMF) in the inner heliosphere. This requires a substantial modification in the modeling of the ion distribution and more detailed measurements, tasks that can be addressed in the near future.     

生物组织光学参数：优化散射系数（μ’s）的实时在位测定

利用了一套特殊设计光纤探头组成的稳定态光纤光谱仪测试生物组织的光学参数,从悬乳液(Intralpid)与模拟胶(Phantom)实验推导出优化散射系数(Reduced scattering coeffcient：μ’s)近红外谱测量经验公式。测量反射系数就可以计算出优化散射系数谱。计算结果用模拟胶作了验证,并对大鼠脑组织μ’s进行了实时在位测量,从而得到了一种μ’s在位测量的有效方法。