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Burgay M D'Amico N Possenti A Manchester RN Lyne AG Joshi BC McLaughlin MA Kramer M Sarkissian JM Camilo F Kalogera V Kim C Lorimer DR 《Nature》2003,426(6966):531-533
The merger of close binary systems containing two neutron stars should produce a burst of gravitational waves, as predicted by the theory of general relativity. A reliable estimate of the double-neutron-star merger rate in the Galaxy is crucial in order to predict whether current gravity wave detectors will be successful in detecting such bursts. Present estimates of this rate are rather low, because we know of only a few double-neutron-star binaries with merger times less than the age of the Universe. Here we report the discovery of a 22-ms pulsar, PSR J0737-3039, which is a member of a highly relativistic double-neutron-star binary with an orbital period of 2.4 hours. This system will merge in about 85 Myr, a time much shorter than for any other known neutron-star binary. Together with the relatively low radio luminosity of PSR J0737-3039, this timescale implies an order-of-magnitude increase in the predicted merger rate for double-neutron-star systems in our Galaxy (and in the rest of the Universe). 相似文献
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Reconstitution of active dimeric ribulose bisphosphate carboxylase from an unfoleded state depends on two chaperonin proteins and Mg-ATP. 总被引:52,自引:0,他引:52
In vitro reconstitution of active ribulose bisphosphate carboxylase (Rubisco) from unfolded polypeptides is facilitated by the molecular chaperones: chaperonin-60 from Escherichia coli (groEL), yeast mitochondria (hsp60) or chloroplasts (Rubisco sub-unit-binding protein), together with chaperonin-10 from E. coli (groES), and Mg-ATP. Because chaperonins are ubiquitous, a conserved Mg-ATP-dependent mechanism exists that uses the chaperonins to facilitate the folding of some other proteins. 相似文献
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McLaughlin MA Lyne AG Lorimer DR Kramer M Faulkner AJ Manchester RN Cordes JM Camilo F Possenti A Stairs IH Hobbs G D'Amico N Burgay M O'Brien JT 《Nature》2006,439(7078):817-820
The radio sky is relatively unexplored for transient signals, although the potential of radio-transient searches is high. This was demonstrated recently by the discovery of a previously unknown type of source, varying on timescales of minutes to hours. Here we report a search for radio sources that vary on much shorter timescales. We found eleven objects characterized by single, dispersed bursts having durations between 2 and 30 ms. The average time intervals between bursts range from 4 min to 3 h with radio emission typically detectable for <1 s per day. From an analysis of the burst arrival times, we have identified periodicities in the range 0.4-7 s for ten of the eleven sources, suggesting origins in rotating neutron stars. Despite the small number of sources detected at present, their ephemeral nature implies a total Galactic population significantly exceeding that of the regularly pulsing radio pulsars. Five of the ten sources have periods >4 s, and the rate of change of the pulse period has been measured for three of them; for one source, we have inferred a high magnetic field strength of 5 x 10(13) G. This suggests that the new population is related to other classes of isolated neutron stars observed at X-ray and gamma-ray wavelengths. 相似文献
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DR.J.P.Semwal 《天津科技大学学报》2004,19(Z1)
INTRODUCTION
India is among one of the ten most industrialized nations in the world. Increase in population has raised the urbar industrial, transport and agriculture demands which are major reasons for the degradation of the environmel condition. For India besides land and soil degradation, deforestation, low accessibility of water, ,industrial pollution and urban congestion are the major environmental issues of priority. The industries that generate huge quantities of waste are thermal power station, Iron and Steel Plants, Sugar, Paper and Fertilizer Industries. 相似文献
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GroE heat-shock proteins promote assembly of foreign prokaryotic ribulose bisphosphate carboxylase oligomers in Escherichia coli 总被引:66,自引:0,他引:66
Assembly of foreign prokaryotic ribulose bisphosphate carboxylases (Rubiscos) in Escherichia coli requires both heat-shock proteins groEL and groES. GroEL is related to a chloroplast protein implicated in Rubisco assembly. Bacteria and chloroplasts therefore have a conserved mechanism that uses auxiliary proteins to assist in the assembly of Rubisco. 相似文献
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