On the initial expansion of meteor trails

The asymptotic solution of the equation governing the number density n(r,t) of evaporated meteoric atons behind a steadily moving meteor is obtained which is suitable to depict the initial expansion of a meteor trail. Some unusual results of meteor observations are elucidated.     

On the fragmentation processes in the meteoroid streams

Summary Radar observations of the main meteor showers in 1993–1995 carried out by a forward-scatter radiosystem Bologna-Lecce in Italy are analysed and discussed in terms of fragmentation effects even in the orbit of the streams of interplanetary matter. The existence of very small particles in all meteoroid streams is revealed by counts of echoes of durationT≤0.05 s. A progressive fragmentation is observed to procede in any meteoric complex, likely as a possible consequence of the disintegration of larger bodies in the stream. This disintegration appears to be more significant in some meteoric complexes (Geminids, Leonids and δ-Aquarids), in connection with their differentiated structure and composition.     

A new method of discovering new meteor showers from the IMO single-station video meteor database

It has been found that unknown meteor showers could be efficiently discovered from the single station video meteor database of the International Meteor Organization (IMO) by assuming the geocentric velocity and adjusting it within the dynamically permitted range. The mean geocentric velocities of new meteor showers can be obtained, as well as the coordinates of the radiants. The activity period and maximum time can also be obtained if there are sufficient shower meteors. All single station video meteor observations between February 13 and 17 (from 2000 to 2005) in IMO’s database are processed with this method. As a result, two new meteor showers, one near RA=245.10°, Dec=41.82° in Hercules and the other near RA=233.03°, Dec=17.04° in Serpenids, are discovered. Some dynamical characteristics of the new meteor showers are also determined. Considering the random nature on the selection of period in this work, it is expected that there are some more potential new meteor showers in IMO’s video database. Supported by the National Natural Science Foundation of China (Grant No. 10373004)     

Reflection properties of meteor trails in a forward-scatter radar experiment

Summary The distribution of the energy reflected by a meteor trail is strongly connected to the ionization density distribution across and along a meteor trail. Recent forward-scatter observations over the Bologna-Lecce baseline in Italy carried out in 1991–92, show that the number of underdense meteor trails (with electron line densityq≤2.10¹⁴ electrons/mvs. peak signal amplitudes decreases more rapidly with the increasing signal level than what predicted. An exponential (simple and/or log-normal) model is proposed, by taking into account different signal-to-noise ratio thresholds and the Kolmogorov-Smirnov (K-S) procedure is used to test the overall goodness of fit between the set of observations and specified theoretical distributions. It is shown that this model provides a better fit to data mainly for middle-high levels of received power and for values ofq≥10¹³ electrons/m.     

How to estimate the effect of an intense meteor shower on human space activities

In the present age, the potential threat to space projects coming from some intense meteor storms has been noticed. Especially, the increasing activities of mankind in space for scientific, commercial and military purposes have led to an increase in safety-related problems about the satellites, space stations and astronauts. Several new techniques for observing meteors and meteor showers have been developed. However, how to estimate even predict the effect of an intense meteor shower should be further studied. The initial definition about a meteor storm based on visual observations with a Zenithal Hourly Rate of over one thousand seems insufficient, since it only means a storm or burst of meteors in numbers. In 2006 the author suggested a synthetical index of the potential threats about intense activities of meteors; however, it is too complex to determine several parameters. In this paper, the author suggests a Special True Number Flux Density (STNFD). Set a certain energy-limit, or a certain electric-charge-limit, and then calculate the number flux density. Through the comparison between two of the 10 strong meteor showers in recent years it is found that the important factor affecting the space flight security is not only the number of meteoroids, but also their velocities, their average energy and the population index r. Calculations show that Giacobinids, even June Bootids, should be one of the most hazardous meteor showers.     

Baseline effect on the forward-scatter radar reflections from meteor trains

Summary The influence of the baseline orientation on the rate of recorded meteor echoes has been shown from the observations carried out during the Lyrid meteor shower periods in 1992 and 1993 with receivers rectangularly displaced from the transmitting station in Bologna with a baseline length of about 700 km. It is shown that the maximum echo rate precedes or occurs later than the shower radiant culminates (at heights of 80°), favouring the 45° radiant elevation and similar angle between the radiant and the beam axis. The consequences of the measured effect on the meteor flux within the shower and sporadic radiant distribution is discussed.     

On the activity and orbit of the Geminids meteorid stream

Summary The activity of the Geminids meteor shower is studied on the basis of radio observations carried out by the Budrio meteor radar in 1986. The 1986 Geminids have displayed as a distinct meteor shower with an asymmetric curve of activity, the duration between the points of one-quarter strength being 6 days and the maximum at the solar longitude of about 260°.75 (1950.0). The mean orbit and radiant ephemeris of the Geminids are derived on the basis of 191 precise photographic orbits available from the IAU Meteor Data Centre in Lund. Over a time span of 50 years, the semi-major axis, eccentricity and perihelion distance of the stream exhibit variations following the trend of the stream evolution suggested by Williams and Wu.     

Evolution of clans in multiparticle production

An alternative interpretation of the development of the clan structure arising formally from the natural decomposition of the negative binomial multiplicity distribution is presented here. Our approach is based on stochastico-physical ideas of multiple production on the parton level. Specific differential-difference evolution equations have been proposed which besides the elementary processes involving the ingredients of QCD branching describe collective phenomena of clan's collapsing and clan's coherent disintegration.     

Study of the Influence of the Mutual Orientation of Antennas on the Characteristics of a Meteor Radio Channel

We describe equipment and a method for performing an experiment on a short meteor radio line of length 85 km. The feature of the experiment is monitoring of meteor-matter deposition to the atmosphere using a radar located at one point of the radio line with the simultaneous determination of the main radio-line characteristics.     

Objective Quantum Fields,Retrocausality and Ontology

We compare different approaches to quantum ontology. In particular, we discuss an interpretation of quantum mechanics that we call objective quantum field theory (OQFT), which involves retrocausal fields. Here, objective implies the existence of fields independent of an observer, but not that the results of conjugate measurements are predetermined: the theory is contextual. The ideas and analyses of Einstein and Bohr through to more recent approaches to objective realism are discussed. We briefly describe measurement induced projections, the guided wave interpretation, many-universes, consistent histories and modal theories. These earlier interpretations are compared with OQFT. We argue that this approach is compatible both with Bohr’s quantum complementarity and Einstein’s objective realism.     

An observational method for upper-atmospheric wind fluctuations on very small scales

Summary Irregular wind motions in the meteor region ((70÷120) km) on very small space-time scales have been tentatively deduced by radar observations of relatively rare, but long enduring ionized trails of bright meteors (fireballs). The method here presented seems to be proper for the study of the turbulent winds in the upper mesosphere and lower thermosphere.     

On the activity and structure of the Quadrantid meteor stream

Summary The activity of the Quadrantid meteor stream is analysed on the basis of radar observations at Budrio (44.5°N, 11.6°E), Italy, in 1983, 1984 and 1987. The Quadrantids have appeared as a prominent meteor stream and the compound activity curve is symmetrical with the maximum at solar longitude 282.69°±0.06° (equinox 1950.0). The maxima in individual years vary and are consistent with visual observations in corresponding years. Mean orbit of the stream as well as the radiant area were derived from 54 photographic Quadrantid orbits compiled from Meteor Data Centre and Nippon Meteor Society. The mean radiant was found at α=230.8°, δ=49.5° and the radiant area is elongated covering an area of 8°×4°. The photographic orbital elements obtained over a period of almost 40 years follow the trend of orbital evolution of the stream proposed by Hugheset al. (1979).     

Integrated BVRIJHK photometry of galactic globular clusters

Summary We present preliminary BVRI photometric data of 22 galactic globular clusters of the Southern hemisphere. The observations were carried out at the ESO Observatory, during two observing runs in August 1988 (VRI) and March 1989 (BVRI). In both periods half of the total number of nights was used to perform near-infrared (JHK) photometry of the same clusters: the goal of this quasi-contemporary photometry was to obtain a homogeneus sample of galactic clusters photometric observations, on a wavelength range as wide as possible. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.     

Fuzzy set ideas in quantum logics

Fuzzy set theory language and ideas are used to express basic quantum logic notions. The possibility of replacing probabilistic interpretation of quantum mechanics by interpretation based on infinite-valued logics and fuzzy set theory is outlined. Short review of various structures encountered in the fuzzy set approach to quantum logics is given.     

Future solar systems

Widely regarded as pathological variable stars – with erratic photometric and spectroscopic behavior of unknown physical origin – 20 years ago, T Tauri stars (TTSs) turned out in the last decade to be promising laboratories for observing the formation of solar systems such as ours. This is because circumstellar, presumably protoplanetary disks were found to surround a large fraction of them. While evidence for disks was primarily indirect until 1995, recent high resolution imaging confirmed earlier claims that the infrared (IR) and ultraviolet (UV) excesses seen in the spectral energy distribution (SED) of these stars were due to disk emission. The activity displayed by young stellar objects at all wavelengths is due to the interaction between the circumstellar disk and the magnetized star and to non-stationary accretion/ejection phenomena. In this review, we briefly summarize properties of these young solar-type stars and describe their circumstellar disks in some detail, focusing on current optical, infrared and millimeter high angular resolution observations that now allow us to resolve the disks.     

Towers of gravitational theories

In this essay we introduce a theoretical framework designed to describe black hole dynamics. The difficulties in understanding such dynamics stems from the proliferation of scales involved when one attempts to simultaneously describe all of the relevant dynamical degrees of freedom. These range from the modes that describe the black hole horizon, which are responsible for dissipative effects, to the long wavelength gravitational radiation that drains mechanical energy from macroscopic black hole bound states. We approach the problem from a Wilsonian point of view, by building a tower of theories of gravity each of which is valid at different scales. The methodology leads to multiple new results in diverse topics including phase transitions of Kaluza-Klein black holes and the interactions of spinning black hole in non-relativistic orbits. Moreover, our methods tie together speculative ideas regarding dualities for black hole horizons to real physical measurements in gravitational wave detectors.     

Oscillator strengths and lifetimes for the P XII

Semi-empirical weighted oscillator strengths (gf) and lifetimes presented in this work for all experimentally known electric dipole P XII spectral lines and energy levels were computed within a multiconfiguration Hartree-Fock relativistic approach. In this calculation, the electrostatic parameters were optimized by a leastsquares procedure in order to improve the adjustment to experimental energy levels. The method produces lifetime and gf values that are in agreement with intensity observations used for the interpretation of spectrograms of solar and laboratory plasmas.     

Generalized Gibbs’ approach to the thermodynamics of heterogeneous systems and the kinetics of first-order phase transitions

In the theoretical interpretation of the kinetics of first-order phase transitions, thermodynamic concepts are widely employed that were developed long ago by Gibbs and van der Waals. However, the results of such analysis are partly unsatisfactory and internally contradictory. By generalizing Gibbs’ approach, the existing deficiencies and internal contradictions of these two well-established theories can be removed and a new generally applicable tool for the interpretation of these processes can be developed. The basic ideas of the generalized Gibbs approach and a variety of consequences obtained on its basis with respect to the understanding of the general features of the kinetics of first-order phase transitions are outlined. Dedicated to the memory of Vladimir P. Skripov. The text was submitted by the authors in English.     

环境样品中痕量铝的现代光度分析研究新进展

论文综述和评论了近年来环境样品中痕量铝的光度分析研究新进展。重点论述了现代光度分析法测定环境样品中铝的研究新进展 ,内容包括 :胶束增溶分光光度法、双波长分光光度法、导数分光光度法、催化光度法、固相光度法、流动注射光度法。对普通光度法和胶束增溶光度法的反应体系、测定条件、摩尔吸收系数 (ε)或检出限、线性范围及其应用进行了归纳总结 ,评述了各种光度法测定的优劣 ,展望了光度法测定痕量铝的发展前景     

Debris from comet Halley, comet's mass loss and age

Summary Large particles released from the nucleus of comet Halley, but undetected directly by space probes, seem to affect decisively the mass loss and mass determination of the comet, and consequently its aging. Simultaneous radar meteor observations in 1985–86 at the approaches of the comet emphasize the relatively larger proportion of long-duration echoes with respect to previous years.