Geomagnetic pulsations

Conclusion In writing this review paper the author has been aware that although the present international classification on geomagnetic pulsations (see Table I) had been really useful for several years since the Berkeley Meeting, it seems unsuitable for the up-to-date pulsation study. This is mainly due to the fact that it depends only on the period and waveform of the pulsations. For example, (1) occurrence of PP type of Pc1 even in the international Pc3 range (Heacock, 1966), (2) PP and CE getting mixed in a common period band (cf. 2.7), (3) similar mixing tendency of Pc3 with Pc4 (cf. 3.3 or Figure 21), (4) subtypes of Pi pulsations having common period ranges but different source mechanisms, (5) existence of various types of pulsations which can be classified neither to Pc nor to Pi (cf. Section 6), and so on. Hence the author feels that a new pulsation classification based on physical image on the occurrence models is really needed now.According to the international definition which has a period range of pulsations from 0.2 (5 Hz) to 600 sec, a part of the following electromagnetic field fluctuations called ELF emissions and ELF whistlers should belong to geomagnetic pulsations. ELF emissions are at times observed near 4 Hz and 9 Hz. They are so termed because of the difference between these frequencies and the Schumann resonance frequencies of 8 and 14 Hz (Yanagihara and Shimizu, 1969; Polk, 1969). Another type, ELF whistlers, exhibit either rising, falling or fluctuating tones from about 2 Hz to probably a few tens of Hz (Duffus, Nasmyth et al., 1958; Yamashita, 1967; Glangeaud, 1967; Yanagihara and Shimizu, 1969). In this review paper, however, both ELF emissions and whistlers have not been reviewed, since most of these seem to be out of the international frequency range so far as present observational knowledge is concerned. Some of the Pc6 and Dp2, involved in the international period range of pulsations, have also not been commented on, but the reader is advised to refer to Herron (1967) and Nishida (1968), respectively, for more detail.It has been frequently pointed out in this paper that latitudinal dependence of pulsation amplitude is one of the most important clues for seeking the model of excitation and propagation of HM and EM waves, but that this dependence has not been precisely obtained so far owing to the difference in geomagnetic longitude of the pulsation stations (for example, see Figure 40). Cooperative observations based on standardized magnetometers are eagerly desired at stations which are densely arranged along the same magnetic meridian, even if the observation is temporal.As already reviewed, various conflicting models have been proposed for each type of pulsation. On the occurrence of pc's, for example, there are two main conflicting models. In the first model, Pc2, 3, and 4 (Troitskaya, 1967; Patel and Hastings, 1968; and others) or Pc3 and 4 (Radoski and Carovillano, 1966) are related to one and the same resonance system and the difference in the type of these pc's is attributed to an effect of geomagnetic activity on the size of this system. In the second model, Pc2, 3, 4 and 5 are related to three or four different resonant systems (Jacobs and Sinno, 1960b; Hirasawa and Nagata, 1966; Kato, Mori et al., 1968; and others). Most of the conflict among such models seems to be removable by combining more thorough theoretical studies and correct dynamic spectrum analyses of the data at the polar region, auroral zone, sub-auroral zone, and middle and low latitudes, for various geomagnetic disturbance conditions.     

New insights into SNR evolution revealed by the discovery of recombining plasmas

We report the discovery of recombining plasmas in three supernova remnants (SNRs) with the Suzaku X-ray astronomy satellite. During SNR’s evolution, the expanding supernova ejecta and the ambient matter are compressed and heated by the reverse and forward shocks to form an X-ray emitting hot plasma. Since ionization proceeds slowly compared to shock heating, most young or middle-aged SNRs have ionizing (underionized) plasmas. Owing to high sensitivity of Suzaku, however, we have detected radiative recombination continua (RRCs) from the SNRs IC 443, W49B, and G359.1–0.5. The presence of the strong RRC is the definitive evidence that the plasma is recombining (overionized). As a possible origin of the overionization, an interaction between the ejecta and dense circumstellar matter is proposed; the highly ionized gas was made at the initial phase of the SNR evolution in dense regions, and subsequent rapid adiabatic expansion caused sudden cooling of the electrons. The analysis on the full X-ray band spectrum of IC 443, which is newly presented in this paper, provides a consistent picture with this scenario. We also comment on the implications from the fact that all the SNRs having recombining plasmas are correlated with the mixed-morphology class.     

Solar power sail membrane prototype for OKEANOS mission

This paper reports on the manufacturing and evaluation of a solar power sail membrane prototype for the OKEANOS project. The in-house prototype was built by the Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency. Mechanical and electrical evaluation tests were conducted. The membrane, thin-film solar cells, reflectivity control devices were good condition after the manufacturing and handling. The improvements in the manufacturing process and design were found. The manufacturing process and design were fundamentally established. After the prototype, improvement plans for the manufacturing process and design were tried. We have a prospect of manufacturing the flight model sail and continue to the development.     

An Adaptive Antenna for Rejection of Wideband Interference

A modification to the adaptive array under the directional constraint [1] is proposed to improve its performance of rejecting wideband interference. By analogy to the pattern synthesis of an antenna array which produces a flat null in its radiation pattern, an additional quantity that corresponds to the derivative of the pattern is generated and combined with the standard feedback quantity to control the weights of the array. This composite system is tested by computer simulation experiments and the following points are demonstrated in contrast to the conventional, simple system: 1) faster adaptation against wideband interference, 2) remarkable improvement of the signal-to-noise ratio of the output, i. e., very small fluctuation.     

Long-period irregular magnetic pulsation,Pi3

In the 1973 Scientific Assembly, the International Association of Geomagnetism and Aeronomy proposed with Resolution No. 11 to settle two new classes of magnetic pulsations; Pc6 having a sinusoidal waveform with periods longer than 600 s and Pi3 having an irregular waveform with periods longer than 150 s. The present paper reviews the studies on these pulsations putting a stress on Pi3. the Pi3-type pulsations are further classified into Psc5, Psc6, Pip, Ps6 and another type. The pulsations Psc5 and Psc6 mean the damped-type pulsations associating with storm sudden commencement in the approximate period range from 150 to 600 s and longer than 600 s, respectively, while Pip and Ps6 are the quasi-sinusoidal pulsations associating with magnetospheric substorm in the appropriate period range from 100 to 400 s and from 5 to 40 min, respectively. In the present review paper a stress is further layed on morphology and theory of the Ps6-type Pi3 pulsation. The following two-snake model is concluded to be plausible. A current system with in-flowing field-aligned current, westward ionospheric current, and out-flowing field-aligned current expands toward both the dawn- and the dusk-sectors with the progress of magnetospheric substorm. Thus Ps6 is regarded to be due to a magnetic effect of a meandering of the current system during the expansion, which is compared with the meandering of two snakes along the auroral oval from the midnight point toward both the east and the west, respectively.     

On Embedding a Qualitative Representation in a Two-Dimensional Plane

Abstract

This paper discusses embedding in a two-dimensional plane a symbolic representation for spatial data using the simple objects, points (P), lines (L), circuits (C), and areas (A). We have proposed PLCA as a new framework for a qualitative spatial reasoning. In a PLCA expression, the entire figure is represented in a form in which all the objects are related. We investigate the conditions for two-dimensional realizability of a PLCA expression, and derive the relation that the numbers of objects in a PLCA expression should have. In this process, we use the well-known Euler's formula. We also give an algorithm for drawing the figure of the PLCA expression that satisfies this condition in a two-dimensional plane and prove its correctness. The algorithm generates a quantitative expression from qualitative expression.     

The effect of the configuration and the interior design of a virtual weightless space station on human spatial orientation

In a virtual weightless environment, subjects’ orientation skills were studied to examine what kind of cognitive errors people make when they moved through the interior space of virtual space stations and what kind of visual information effectively decreases those errors. Subjects wearing a head-mounted display moved from one end to the other end in space station-like routes constructed of rectangular and cubical modules, and did Pointing and Modeling tasks. In Experiment 1, configurations of the routes were changed with such variables as the number of bends, the number of embedding planes, and the number of planes with respect to the body posture. The results indicated that spatial orientation ability was relevant to the variables and that orientational errors were explained by two causes. One of these was that the place, the direction, and the sequence of turns were incorrect. The other was that subjects did not recognize the rotation of the frame of reference, especially when they turned in pitch direction rather than in yaw. In Experiment 2, the effect of the interior design was examined by testing three design settings. Wall colors that showed the allocentric frame of reference and the different interior design of vertical and horizontal modules were effective; however, there was a limit to the effectiveness in complicated configurations.     

Mineral-enhanced hydrothermal oligopeptide formation at the second time scale

Accumulation of biopolymers should have been an essential step for the emergence of life on primitive Earth. However, experimental simulations for submarine hydrothermal vent systems in which high-temperature water spouts through minerals within a short time scale have not been attempted. Here, we show that enhancement of hydrothermal oligopeptide elongation by naturally occurring minerals was successfully verified for the first time by using a mineral-mediated hydrothermal flow reactor system (MMHF). MMHF consists of a narrow tubular reactor packed with mineral particles, and the enhancement or inhibitory activities of 10 types of naturally occurring minerals were successfully evaluated for an elongation reaction from (Ala)(4) to (Ala)(5) and higher oligopeptides in the absence of condensation reagents. It was unexpected that calcite and dolomite facilitated the elongation from (Ala)(4) to (Ala)(5) and higher oligopeptides with 28% yield at pH 7, while tourmaline, galena, apatite, mica, sphalerite, quartz, chalcopyrite, and pyrite did not show enhancement activities. These facts suggest the importance of carbonate minerals for the accumulation of peptide in primitive Earth environments.     

The United Nations Programme on Space Applications: Status and direction for 2010

The United Nations Programme on Space Applications was established in 1971 to assist countries in making full use of the benefits of space technology and its applications for social and economic development. Since its inception the programme has organized numerous training courses, workshops, seminars and conferences and provided funding support for more than 10?000 experts, mainly from developing countries, to participate in those activities. The programme has continuously evolved over four decades, taking into account the latest developments in the field of space activities, to best serve the capacity-building needs of countries and to help ensure that space-based solutions contribute to improving life on Earth. This report describes the status and direction of the UN Programme on Space Applications as recommended for approval by the UN’s Committee on the Peaceful Uses of Outer Space (UNCOPUOS) Scientific and Technical Subcommittee at its 47th session held in Vienna in February 2010.