Survival and alteration of the plasmid-containing microorganism Escherichia coli Z905/pPHL7 introduced into manmade closed aquatic microcosms.

It has been demonstrated that the transgenic microorganism Escherichia coli Z905/pPHL7 (AprLux+) can exist for a long time at an elevated concentration of mineral salts. The microorganism was introduced into microcosms with sterile brackish water (salinity variable from 21 to 22 g l-1) taken from Lake Shira (Khakasia, Russia). The survival of the microorganism was estimated both by measuring the growth of the colonies on solid nutrient media and by the bioluminescence exhibited by the transgenic strain in samples from the microcosms and in the enrichment culture with the added selective factor-ampicillin (50 micrograms/ml). In the enrichment culture, the bioluminescent signal was registered through the 160-day experiment. It has been shown that in the closed microcosms with brackish water the E. coli strain becomes heterogeneous in its ampicillin resistance. The populations of the transgenic strain were mainly represented by isolates able to persist in the medium containing 50 micrograms/ml, but there were also the cells (about 10%) with the threshold of ampicillin resistance not more than 0.05 micrograms/ml. Thus, it was shown that in the microcosms with brackish water and in the absence of the selective factor the transgenic strain survives and retails the recombinant plasmid.     

Periods of quasi-stationary conditions in interplanetary space according to sequences of SEP events

The values of the characteristic decay time of particle fluxes in SEP events vary, as a rule, considerably from event to event. We point out, however, that at times sequences of events having similar decay times were observed over long time intervals (up to one month, and even longer in a few cases). The values of the decay times, however, differed among different sequences. The constancy of the decay phase in each consecutive event of these series suggests that the interplanetary medium was in steady state during the event series, and, because of solar rotation, its uniformity within sectors extended to 90–180° in heliolongitude. The very rarely observed long series (up to 2–3 solar rotations) indicate the steadiness and homogeneity of the plasma and the interplanetary magnetic field (IMF) in the entire inner solar system in the course of this time span. It is pointed out that the neutral current sheet of the IMF does not represent a substantial obstacle for energetic charged particles. Both hemispheres are (above and below the current sheet), at least during the series of solar events, invariant with time, uniform and alike from the viewpoint of the propagation of charged particles. The investigation of such sequences of events can also be useful for forecasting characteristics of SEP events.     

Electric Polarization of Low-Orbit Spacecraft

The main problems concerning the electric polarization of low-orbit spacecraft are considered, including the results of studying the structure of the Earth's upper ionosphere, the methods of calculating the electrophysical characteristics of construction materials for spacecraft, and the elaboration of recommendations to mitigate the negative effects due to processes of charging and discharging.     

Ionization and recombination processes determining plasma density at the initial stage of artificial cloud injection

The initial reduction of the electron density after the injection explosion is shown to be associated with recombination at the adiabatic cooling under the cloud expansion. Primordial thermal ions can disappear in triple collisions almost entirely. Nevertheless, a minor amount of ions is conserved due to the freezing effect. The further rapid increase in the electron concentration may be attributed to the secondary ionization process. It is shown that the cumulative electronic ionization can account for the observed electron density elevation. The modified two-stream instability can provide a longitudinal (anomalous) resistance for the longitudinal electric field required for an avalanche. The electric field and longitudinal currents arise owing to the polarization with ions entrained by the neutral gas across the magnetic field and magnetized electrons moving along the field.     

The Earth's Magnetosphere Response to Solar Wind Events according to the INTERBALL Project Data

The results of studying the interaction of two types of the solar wind (magnetic clouds and solar wind of extremely low density) with the Earth's magnetosphere are discussed. This study is based of the INTERBALL space project measurements and on the other ground-based and space observations. For moderate variations of the solar wind and interplanetary magnetic field (IMF) parameters, the response of the magnetosphere is similar to its response to similar changes in the absence of magnetic clouds and depends on a previous history of IMF variations. Extremely large density variations on the interplanetary shocks, and on leading and trailing edges of the clouds result in a strong deformation of the magnetosphere, in large-scale motion of the geomagnetic tail, and in the development of magnetic substorms and storms. The important consequences of these processes are: (1) the observation of regions of the magnetosphere and its boundaries at great distances from the average location; (2) density and temperature variations in the outer regions of the magnetosphere; (3) multiple crossings of geomagnetic tail boundaries by a satellite; and (4) bursty fluxes of electrons and ions in the magnetotail, auroral region, and the polar cap. Several polar activations and substorms can develop during a single magnetic cloud arrival; a greater number of these events are accompanied, as a rule, by the development of a stronger magnetic storm. A gradual, but very strong, decrease of the solar wind density on May 10–12, 1999, did not cause noticeable change of geomagnetic indices, though it resulted in considerable expansion of the magnetosphere.     

快速成型技术（RP技术）对产品开发的影响

快速成型技术是目前工业领域内一门崭新的技术，为产品开发过程开辟了一个截然不同的新思路。本文首先介绍RP技术的发展及常用的几种RP处理系统；通过RP技术生成的试件原型在开发过程中的作用，说明RP技术对产品开发的影响；文章最后提出RP技术应用的前提条件。     

“自由伊拉克作战”检讨报告——轮式车与无人载具

虽然“自由伊拉克作战”（Operation Iraqi Freedom）已经告一段落，但是美军在伊拉克所面对的问题却是有增无减，其中又以伊拉克反美武装所实施的攻击为甚，虽然美军、联军和伊拉克过渡政府的保安部队坐拥15万兵力，但是却无法避免伊拉克反美武装对美军接二连三攻击所造成的有生力量伤亡，截至2005年2月18日为止，美军总计有1462名官士兵阵亡（含军方雇员），10968人负伤，换言之，美军在2003年5月15日结束“自由伊拉克作战”之后，在作战行动中阵亡的官兵仅仅只有109名，但是在战后因为伊拉克伊拉克反美武装攻击而阵亡的官士兵却已经堂堂突破1000大关，足足是作战阵亡人数的10倍，更不用提上万名的负伤者。[编者按]     

田捷砚凌空飞撷西部大地之美

应该感谢摄影家田捷砚数年数以百次不知倦怠的艰辛西部航拍之旅，以及他在某种高度上忘我创作的数以万张的精彩图片，让我们心驰神往的境界变成可观可感的实际图像。[编按]     

双向进气结构脉管制冷机直流形成机理

在脉管制冷机中,由双向进气结构诱发的直流流动,不仅会增加冷端换热器的负载,降低制冷机性能,而且还是引起制冷温度不稳定的重要原因。如何有效地抑制直流流动已成为脉管制冷机能否大规模应用的关键。而对直流形成机理进行全面、深入的研究是发展简单、有效直流抑制手段的前提。针对该研究热点,本文开展了双向进气结构脉管制冷机直流形成机理研究,基于流体网络理论,考察工质物性对直流的影响和作用机理,进一步揭示了直流的形成本质。