Massive multiple-input multiple-output(MIMO)technology enables higher data rate transmission in the future mobile communications.However,exploiting a large number of antenna elements at base station(BS)makes effective...Massive multiple-input multiple-output(MIMO)technology enables higher data rate transmission in the future mobile communications.However,exploiting a large number of antenna elements at base station(BS)makes effective implementation of massive MIMO challenging,due to the size and weight limits of the masssive MIMO that are located on each BS.Therefore,in order to miniaturize the massive MIMO,it is crucial to reduce the number of antenna elements via effective methods such as sparse array synthesis.In this paper,a multiple-pattern synthesis is considered towards convex optimization(CO).The joint convex optimization(JCO)based synthesis is proposed to construct a codebook for beamforming.Then,a criterion containing multiple constraints is developed,in which the sparse array is required to fullfill all constraints.Finally,extensive evaluations are performed under realistic simulation settings.The results show that with the same number of antenna elements,sparse array using the proposed JCO-based synthesis outperforms not only the uniform array,but also the sparse array with the existing CO-based synthesis method.Furthermore,with a half of the number of antenna elements that on the uniform array,the performance of the JCO-based sparse array approaches to that of the uniform array.展开更多
Pluripotent stem cells(PSCs),including embryonic stem cells(ESCs)and induced PSCs(iPSCs),can differentiate into cells of the three germ layers,suggesting that PSCs have great potential for basic developmental biology ...Pluripotent stem cells(PSCs),including embryonic stem cells(ESCs)and induced PSCs(iPSCs),can differentiate into cells of the three germ layers,suggesting that PSCs have great potential for basic developmental biology research and wide applications for clinical medicine.Genuine ESCs and iPSCs have been derived from mice and rats,but not from livestock such as the pig-an ideal animal model for studying human disease and regenerative medicine due to similarities with human physiologic processes.Efforts to derive porcine ESCs and iPSCs have not yielded high-quality PSCs that can produce chimeras with germline transmission.Thus,exploration of the unique porcine gene regulation network of preimplantation embryonic development may permit optimization of in vitro culture systems for raising porcine PSCs.Here we summarize the recent progress in porcine PSC generation as well as the problems encountered during this progress and we depict prospects for generating porcine naive PSCs.展开更多
It is not fully clear why there is a higher contribution of pluripotent stem cells （PSCs） to the chimera produced by injection of PSCs into 4-cell or 8-cell stage embryos compared with blastocyst injection. Here, we...It is not fully clear why there is a higher contribution of pluripotent stem cells （PSCs） to the chimera produced by injection of PSCs into 4-cell or 8-cell stage embryos compared with blastocyst injection. Here, we show that not only embryonic stem cells （ESCs） but also induced pluripotent stem cells （iPSCs） can generate F0 nearly 100% donor cell-derived mice by 4-cell stage embryo injection, and the approach has a ＂dose effect＂. Through an analysis of the PSC-secreted proteins, Activin A was found to impede epiblast （EPI） lineage development while promoting trophectoderm （TE） differentiation, resulting in replacement of the EPI lineage of host embryos with PSCs. Interestingly, the injection of ESCs into blastocysts cultured with Activin A （cultured from 4-cell stage to early blastocyst at E3.5） could increase the contribution of ESCs to the chimera. The results indicated that PSCs secrete protein Activin A to improvetheir EPI competency after injection into recipient embryos through influencing the development of mouse early embryos. This result is useful for optimizing the chimera production system and for a deep understand- ing of PSCs effects on early embryo development.展开更多
As a candidate technique to achieve sixth-generation wireless communication(6G),reconfigurable intelligent surface(RIS)has become popular in both academia and industry.For better exploration of the advantages of RIS,w...As a candidate technique to achieve sixth-generation wireless communication(6G),reconfigurable intelligent surface(RIS)has become popular in both academia and industry.For better exploration of the advantages of RIS,we compare the performances of RIS and network-controlled repeater(NCR)in 3GPP release-18.We first theoretically analyze the received signal power and signal-to-noise ratio performances for both RIS and NCR.Then,we simulate the reference signal received power and signal-to-interference-and-noise ratio performances at the system level for both RIS and NCR in the frequency range 1 and frequency range 2 bands.Finally,several insights on engineering applications are given based on the comparison between RIS and NCR.展开更多
文摘Massive multiple-input multiple-output(MIMO)technology enables higher data rate transmission in the future mobile communications.However,exploiting a large number of antenna elements at base station(BS)makes effective implementation of massive MIMO challenging,due to the size and weight limits of the masssive MIMO that are located on each BS.Therefore,in order to miniaturize the massive MIMO,it is crucial to reduce the number of antenna elements via effective methods such as sparse array synthesis.In this paper,a multiple-pattern synthesis is considered towards convex optimization(CO).The joint convex optimization(JCO)based synthesis is proposed to construct a codebook for beamforming.Then,a criterion containing multiple constraints is developed,in which the sparse array is required to fullfill all constraints.Finally,extensive evaluations are performed under realistic simulation settings.The results show that with the same number of antenna elements,sparse array using the proposed JCO-based synthesis outperforms not only the uniform array,but also the sparse array with the existing CO-based synthesis method.Furthermore,with a half of the number of antenna elements that on the uniform array,the performance of the JCO-based sparse array approaches to that of the uniform array.
基金This work was funded by the National Key Basic Research and Development Program of China(2010CB945404,2011CBA01001 and 2009CB941003)the Chinese Universities Scientific Fund(2012RC014)the National Thousand Talents Program of China.
文摘Pluripotent stem cells(PSCs),including embryonic stem cells(ESCs)and induced PSCs(iPSCs),can differentiate into cells of the three germ layers,suggesting that PSCs have great potential for basic developmental biology research and wide applications for clinical medicine.Genuine ESCs and iPSCs have been derived from mice and rats,but not from livestock such as the pig-an ideal animal model for studying human disease and regenerative medicine due to similarities with human physiologic processes.Efforts to derive porcine ESCs and iPSCs have not yielded high-quality PSCs that can produce chimeras with germline transmission.Thus,exploration of the unique porcine gene regulation network of preimplantation embryonic development may permit optimization of in vitro culture systems for raising porcine PSCs.Here we summarize the recent progress in porcine PSC generation as well as the problems encountered during this progress and we depict prospects for generating porcine naive PSCs.
基金This work was supported by The National Key Research and Development Program of China （2016YFA0100202）, National Nat- ural Science Foundation of China （Grant Nos. 31571497 and31601941 ）, Beijing Natural Science Foundation of China （6152004）, The National Thousand Talents Program of China and Research Programs from the State Key Laboratory for Agrobiotechnology, China Agricultural University （grant numbers 2015SKLAB1-4, 2017SKLAB1-2）.
文摘It is not fully clear why there is a higher contribution of pluripotent stem cells （PSCs） to the chimera produced by injection of PSCs into 4-cell or 8-cell stage embryos compared with blastocyst injection. Here, we show that not only embryonic stem cells （ESCs） but also induced pluripotent stem cells （iPSCs） can generate F0 nearly 100% donor cell-derived mice by 4-cell stage embryo injection, and the approach has a ＂dose effect＂. Through an analysis of the PSC-secreted proteins, Activin A was found to impede epiblast （EPI） lineage development while promoting trophectoderm （TE） differentiation, resulting in replacement of the EPI lineage of host embryos with PSCs. Interestingly, the injection of ESCs into blastocysts cultured with Activin A （cultured from 4-cell stage to early blastocyst at E3.5） could increase the contribution of ESCs to the chimera. The results indicated that PSCs secrete protein Activin A to improvetheir EPI competency after injection into recipient embryos through influencing the development of mouse early embryos. This result is useful for optimizing the chimera production system and for a deep understand- ing of PSCs effects on early embryo development.
文摘As a candidate technique to achieve sixth-generation wireless communication(6G),reconfigurable intelligent surface(RIS)has become popular in both academia and industry.For better exploration of the advantages of RIS,we compare the performances of RIS and network-controlled repeater(NCR)in 3GPP release-18.We first theoretically analyze the received signal power and signal-to-noise ratio performances for both RIS and NCR.Then,we simulate the reference signal received power and signal-to-interference-and-noise ratio performances at the system level for both RIS and NCR in the frequency range 1 and frequency range 2 bands.Finally,several insights on engineering applications are given based on the comparison between RIS and NCR.
