OAM Modes in Optical Fibers for Next Generation Space Division Multiplexing (SDM) Systems

Due to the renewed demand on data bandwidth imposed by the upcoming capacity crunch, optical communication (research and industry) community has oriented their effort to space division multiplexing (SDM) and particularly to mode division multiplexing (MDM). This is based on separate/independent and orthogonal spatial modes of optical fiber as data carriers along optical fiber. Orbital Angular Momentum (OAM) is one of the variants of MDM that showed promising features including the efficient enhancement of capacity transmission from Tbit to Pbit and substantial improvement of spectral efficiency up to hundreds (bs-1 Hz-1). In this chapter, we review the potentials of harnessing SDM as a promising solution for next generation global communications systems. We focus on different SDM approaches and we address specifically the MDM (different modes in optical fiber). Finally, we highlight the recent main works and achievements that have been conducted (in last decade) in OAM-MDM over optical fibers. We focus on main R&D activities incorporating specialty fibers that have been proposed, designed and demonstrating in order to handle appropriates OAM modes.

A Bibliometric Analysis of Overall and Top 100 Most-Cited Studies About Robotic Surgery Versus Open Surgery

Background In the last 30 years, significant progress in the field of surgery has been achieved with the advent of robotic surgery. In this study, we aimed to conduct a bibliometric analysis to identify the distribution and characteristics overall and of the top 100 most-cited studies about robotic surgery versus open surgery. Methods A systematic search was conducted on March 26, 2021 using Web of Science Core Collection. Two reviewers independently screened documents, and the top 100 most-cited studies were identified. Excel 2019 and VOSviewer were used to collect the data, and visual information was obtained. Results A total of 2306 documents were searched from the Web of Science Core Collection, and 1065 journals and 2913 institutes were extracted. A significant growth was observed in the last 15 years. The number of citations from the United States accounted for 33.31% of the total number of citations. There were nine American institutes and one Swedish institute in the top 10 institutes. Four journals in the field of urology or gynecology were present in the top 10 published journals. Few global communications between authors, institutes, and countries authors were observed. Conclusion The lack of close cooperation among scientific research institutions may have affected the industrialization process of surgical robots. Some developing countries, including South America and Africa, should seize the development opportunity of robotic surgery to improve the level of domestic research on robotic surgery.

About benefits and harms of rewriting history. One of the topics of contemporary historical discourses: philosophical analysis

When we talk about historical revisionism, negative connotations as a rule are prevailing. Prohibition of revision of certain historical interpretation and assessment is one of the tasks of historical policy which is carried out by adopting so-called «memorial laws». Taking care of the formation of the desired representations of the past (narratives) is directly related to the interests of institutionalized power in its own stabilization and strengthening. Power is a function of the community, whose identity is formed historically. Consolidation of collective identity through the support and reproduction of common representations of the past is one of the tools to strengthen power. At the same time, the very nature of human experience acquisition which is permanent mediation of the horizon of the past and the present, presuppose a reinterpretation of this past. Major shifts in the experience of generations, which occur as a result of certain social changes, lead to a new look at the past of the community. In this sense, rethinking and rewriting history becomes necessary to clarify, update, rationalize the collective identity, which is problematized by new experience. Historical policy can both respond to this need for identity transformation through re- thinking representations of one’s own past and come into conflict with it. In the latter case, the narratives transferring by institutional power begin to conflict with the communicative memory of the generation experiencing a shift. One of the tools of self-preservation of power in this situation is blocking of living historical experience, which can take various forms. The culmination of such a blockade is «hermetization» of historical time that take place in totalitarian state. The living historicity of experience, which requires a constant rethinking of one’s own historically inherited identity, is replaced by an artificial, time-frozen identity, which, precisely because of this nature, becomes fragile and doomed to destruction. On the other hand, the rewriting of history initiated by the authorities within the framework of historical policy may face resistance to the representations of the past rooted in the communicative and cultural memory. The resistance of historical narratives indicates that the collective memory and the identity founded in it are not only a power construct, but also a spontaneous layering of sediments of historical experience. In today’s world of global communications and unified everyday practices, historical narratives are beginning to play an increasing role, as they remain the only seat of identity. At the same time, this process reinforces the conflict potential of communities, which can be observed in many examples of the revival of historically motivated political ambitions. In this situation, a critical clarification of various interpretations of the past becomes a means of rationalizing the historically inherited identity of communities as a necessary condition for intercultural dialogue.