Reconfigurable intelligent surface:design the channel-a new opportunity for future wireless networks

In this paper,we survey state-of-the-art research outcomes in the burgeoning field of Reconfigurable Intelligent Surface(RIS),given its potential for significant performance enhancement of next-generation wireless communication networks by means of adapting a propagation environment.Emphasis has been placed on several aspects gating the commercial viability of future network deployment.Comprehensive summaries are provided for practical hardware design considerations and broad implications of artificial intelligence techniques,as are in-depth outlooks on the salient aspects of system models,use cases,and physical layer optimization techniques.

Kidney exchange transplantation current status, an update and future perspectives

Kidney exchange transplantation is well established modality to increase living donor kidney transplantation. Reasons for joining kidney exchange programs are ABO blood group incompatibility, immunological inco-mpatibility(positive cross match or donor specific antibody), human leukocyte antigen(HLA) incompa-tibility(poor HLA matching), chronological incompa-tibility and financial incompatibility. Kidney exchange transplantation has evolved from the traditional si-multaneous anonymous 2-way kidney exchange to more complex ways such as 3-way exchange, 4-way exchange, n -way exchange,compatible pair, non-simult-aneous kidney exchange,non-simultaneous extended altruistic donor, never ending altruistic donor, kidney exchange combined with desensitization, kidney ex-change combined with ABO incompatible kidney tr-ansplantation, acceptable mismatch transplant, use of A2 donor to O patients, living donor-deceased donor list exchange, domino chain, non-anonymous kidney exchange, single center, multicenter, regional, National, International and Global kidney exchange. Here we discuss recent advances in kidney exchanges such as International kidney exchange transplantation in a gl-obal environment, three categories of advanced dona-tion program, deceased donors as a source of chain initiating kidneys, donor renege myth or reality, pros and cons of anonymity in developed world and(non-) anonymity in developing world, pros and cons of donor travel vs kidney transport, algorithm for management of incompatible donor-recipient pairs and pros and cons of Global kidney exchange. The participating transplant teams and donor-recipient pairs should make the decision by consensus about kidney donor travel vskidney transport and anonymity vs non-anonymity in allocation as per local resources and logistics. Future of organ transplantation in resource-limited setting will be liver vs kidney exchange, a legitimate hope or utopia?