A cat cloned by nuclear transplantation

Sheep, mice, cattle, goats and pigs have all been cloned by transfer of a donor cell nucleus into an enucleated ovum, and now we add the successful cloning of a cat (Felis domesticus) to this list. However, this cloning technology may not be readily extendable to other mammalian species if our understanding of their reproductive processes is limited or if there are species-specific obstacles.     

Behavior of argon gas release from manganese oxide minerals as revealed by <Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar laser incremental heating analysis

Manganese oxides in association with paleo- weathering may provide significant insights into the multiple factors affecting the formation and evolution of weathering profiles, such as temperature, precipitation, and biodiversity. Laser probe step-heating analysis of supergene hollandite and cryptomelane samples collected from central Queensland, Australia, yield well-defined plateaus andconsistent isochron ages, confirming the feasibility dating very-fined supergene manganese oxides by 40Ar/39Ar technique. Two distinct structural sites hostingAr isotopes can be identified in light of their degassing behaviors obtained byincremental heating analyses. The first site, releasing its gas fraction at thelaser power 0.2-0.4 W, yields primarily 40Aratm, 38Aratm, and 36Aratm (atmospheric Ar isotopes). The second sites yield predominantly 40Ar* (radiogenic 40Ar),39ArK, and 38ArK (nucleogenic components), at ～0.5-1.0 W. There is no significant Ar gas released at the laser power higher than 1.0 W, indicating the breakdown of the tunnel sites hosting the radiogenic and nucleogenic components. The excellent match between the degassing behaviors of 40Ar*, 39ArK, and 38ArK suggests that these isotopes occupy the same crystallographic sites and that 39ArK lossfrom the tunnel site by recoil during neutron irradiation and/or bake-out procedure preceding isotopic analysis does not occur. Present investigation supports that neither the overwhelming atmospheric 40Ar nor the very-fined nature of the supergene manganese oxides poses problems in extracting meaningful weathering geochronological information by analyzing supergene manganese oxides minerals.     

光突发交换网络的数据信道分组抢占调度策略研究

光突发交换是面向下一代因特网的光交换模式,它结合了光电路交换和光分组交换的优点,同时克服了他们的一些缺点.介绍了光突发交换网络中一种支持区分服务的数据信道调度策略,通过仿真分析了数据信道分组策略对网络性能的影响,为进一步研究提供了有价值的参考.