distance communication
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Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 608
Author(s):  
Marco Fanizza ◽  
Matteo Rosati ◽  
Michalis Skotiniotis ◽  
John Calsamiglia ◽  
Vittorio Giovannetti

We study the problem of transmitting classical information using quantum Gaussian states on a family of phase-noise channels with a finite decoherence time, such that the phase-reference is lost after m consecutive uses of the transmission line. This problem is relevant for long-distance communication in free space and optical fiber, where phase noise is typically considered as a limiting factor. The Holevo capacity of these channels is always attained with photon-number encodings, challenging with current technology. Hence for coherent-state encodings the optimal rate depends only on the total-energy distribution and we provide upper and lower bounds for all m, the latter attainable at low energies with on/off modulation and photodetection. We generalize this lower bound to squeezed-coherent encodings, exhibiting for the first time to our knowledge an unconditional advantage with respect to any coherent encoding for m=1 and a considerable advantage with respect to its direct coherent counterpart for m>1. This advantage is robust with respect to moderate attenuation, and persists in a regime where Fock encodings with up to two-photon states are also suboptimal. Finally, we show that the use of part of the energy to establish a reference frame is sub-optimal even at large energies. Our results represent a key departure from the case of phase-covariant Gaussian channels and constitute a proof-of-principle of the advantages of using non-classical, squeezed light in a motivated communication setting.


2021 ◽  
Vol 2086 (1) ◽  
pp. 012090
Author(s):  
M E Makarov ◽  
A A Sapegin ◽  
R T Minnullin

Abstract This paper is devoted to numerical simulation of a non-volatile photonic memory cell based on phase-change material Ge2Sb2Te5. The parameters of light propagation are presented for both crystalline and amorphous Ge2Sb2Te5 phases. The cell structure is optimized for a single TE-mode regime that is suitable for short- and long-distance communication lines.


2021 ◽  
Vol 4 (2) ◽  
pp. 197-210
Author(s):  
Selamet Selamet ◽  
Mohammad Erihadiana ◽  
Qiqi Yuliati Zaqiah

Since Indonesia announced that it had been exposed to COVID-19 on March 16, 2020, all forms of activities that trigger social activities were freely dismissed with various Social Distancing, Physical Distancing, and PSBB (large-scale social restrictions) policies. Many sectors are affected by this policy, including the education sector. The Minister of Education and Culture who established online learning (on the network) with an emergency curriculum that he published made learning a little different from usual. There is no face-to-face in the classroom directly and learning is transformed by distance learning that works with parents at home in active communication. The continuity of this learning depends on the teacher providing the material in its implementation, assisted and monitored by the parents of each student. By using whatsapp group media in learning during the COVID-19 pandemic, it is one of the efforts made by teachers in seeking an effective and fun learning. MI Al-Fadliliyah Darussalam continues to strive and is committed to optimally implementing online learning, the teacher's role is very important in the KBM it carries out. The use of whatsapp group media is the most popular media to facilitate long-distance communication, therefore online learning uses this media more often, because it is easier and better known in the community, especially parents. However, of course not only using whatsapp group media is not the end of the online learning solution. There needs to be a strategy and review related to the problems that occur to parents of students. Keywords: WhatsApp group media utilization, learning and the COVID-19 pandemic


Author(s):  
Kanika Khanna ◽  
Sukhmeen Kaur Kohli ◽  
Vinod Kumar ◽  
Jaspreet Kour ◽  
Arun Dev Singh ◽  
...  

: Communication among different species across kingdoms occurs through a chain of regulatory molecules that are transferred around cellular boundaries. These molecules are also crucial for defense, virulence and pathogenesis. In the past, the transport of proteins in long distance communication was observed, but in the present era, the discovery of extracellular vesicles (EVs) has changed our understanding of molecular communication. EVs are not only involved in cell signaling and immunity, but also can transfer information by sRNAs, forming a basis for interactions among a wide variety of organisms. Despite extensive research on EVs in other areas, their role in communication between plants and the plant microbiome has been lacking. EVs are potentially involved in protein trafficking along with transport of lipids and nucleic acids. Interactions between hosts and their microbiomes may also be mediated by EVs, which can be involved in stress responses, immune surveillance and defense, virulence and signaling along with many metabolic activities within plant microbiomes. In this review, we have focused on recent information about the role of EVs and the molecules they transport between hosts and microbes. The connection between biofilms and the generation of EVs is also considered. These findings enhance our knowledge about plant-microbiome interactions in terms of immunity and virulence and challenge the conventional viewpoint of inter-kingdom signaling.


2021 ◽  
pp. 55-59
Author(s):  
A. A. Lobanov

The article discusses aspects of the organization of distance learning using educational platforms, the capabilities of Google Tables and distance communication systems. The experience of organizing distance learning also in the mode of full-time education is given. The transition to a distance learning format was the only way to continue training and effective feedback with students in a pandemic, but, as practice has shown, the skills of organizing training in a distance format have been closely integrated into the educational process, especially for an open school. The use of a Russian educational platform with ready-made tools for teaching, monitoring and analyzing the data obtained made it possible in the shortest possible time to restructure the learning process with minimal labor costs for both school teachers and students and their parents.


2021 ◽  
Vol 12 ◽  
Author(s):  
Julien Meyer ◽  
Marcelo O. Magnasco ◽  
Diana Reiss

Humans use whistled communications, the most elaborate of which are commonly called “whistled languages” or “whistled speech” because they consist of a natural type of speech. The principle of whistled speech is straightforward: people articulate words while whistling and thereby transform spoken utterances by simplifying them, syllable by syllable, into whistled melodies. One of the most striking aspects of this whistled transformation of words is that it remains intelligible to trained speakers, despite a reduced acoustic channel to convey meaning. It constitutes a natural traditional means of telecommunication that permits spoken communication at long distances in a large diversity of languages of the world. Historically, birdsong has been used as a model for vocal learning and language. But conversely, human whistled languages can serve as a model for elucidating how information may be encoded in dolphin whistle communication. In this paper, we elucidate the reasons why human whistled speech and dolphin whistles are interesting to compare. Both are characterized by similar acoustic parameters and serve a common purpose of long distance communication in natural surroundings in two large brained social species. Moreover, their differences – e.g., how they are produced, the dynamics of the whistles, and the types of information they convey – are not barriers to such a comparison. On the contrary, by exploring the structure and attributes found across human whistle languages, we highlight that they can provide an important model as to how complex information is and can be encoded in what appears at first sight to be simple whistled modulated signals. Observing details, such as processes of segmentation and coarticulation, in whistled speech can serve to advance and inform the development of new approaches for the analysis of whistle repertoires of dolphins, and eventually other species. Human whistled languages and dolphin whistles could serve as complementary test benches for the development of new methodologies and algorithms for decoding whistled communication signals by providing new perspectives on how information may be encoded structurally and organizationally.


Author(s):  
Patrick McMillen ◽  
Madeleine J. Oudin ◽  
Michael Levin ◽  
Samantha L. Payne

Cellular communication is important in all aspects of tissue and organism functioning, from the level of single cells, two discreet populations, and distant tissues of the body. Long distance communication networks integrate individual cells into tissues to maintain a complex organism during development, but when communication between cells goes awry, disease states such as cancer emerge. Herein we discuss the growing body of evidence suggesting that communication methods known to be employed by neurons, also exist in other cell types. We identify three major areas of long-distance communication: bioelectric signaling, tunneling nanotubes (TNTs), and macrophage modulation of networks, and draw comparisons about how these systems operate in the context of development and cancer. Bioelectric signaling occurs between cells through exchange of ions and tissue-level electric fields, leading to changes in biochemical gradients and molecular signaling pathways to control normal development and tumor growth and invasion in cancer. TNTs transport key morphogens and other cargo long distances, mediating electrical coupling, tissue patterning, and malignancy of cancer cells. Lastly macrophages maintain long distance signaling networks through trafficking of vesicles during development, providing communication relays and priming favorable microenvironments for cancer metastasis. By drawing comparisons between non-neural long distance signaling in the context of development and cancer we aim to encourage crosstalk between the two fields to cultivate new hypotheses and potential therapeutic strategies.


Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6203
Author(s):  
Himangshu Kalita ◽  
Jekan Thangavelautham

Recently discovered pits on the surface of the Moon and Mars are theorized to be remnants of lava tubes, and their interior may be in pristine condition. Current landers and rovers are unable to access these areas of high interest. However, multiple small, low-cost robots that can utilize unconventional mobility through ballistic hopping can work as a team to explore these environments. In this work, we propose strategies for exploring these newly discovered Lunar and Martian pits with the help of a mother-daughter architecture for exploration. In this architecture, a highly capable rover or lander would tactically deploy several spherical robots (SphereX) that would hop into the rugged pit environments without risking the rover or lander. The SphereX robots would operate autonomously and perform science tasks, such as getting inside the pit entrance, obtaining high-resolution images, and generating 3D maps of the environment. The SphereX robot utilizes the rover or lander’s resources, including the power to recharge and a long-distance communication link to Earth. Multiple SphereX robots would be placed along the theorized caves/lava tube to maintain a direct line-of-sight connection link from the rover/lander to the team of robots inside. This direct line-of-sight connection link can be used for multi-hop communication and wireless power transfer to sustain the exploration mission for longer durations and even lay a foundation for future high-risk missions.


Antiquity ◽  
2021 ◽  
pp. 1-17
Author(s):  
Alexey Tarasov ◽  
Kerkko Nordqvist

The hunter-fisher-gatherers of fourth- to third-millennium BC north-eastern Europe shared many characteristics traditionally associated with Neolithic and Chalcolithic agricultural societies. Here, the authors examine north-eastern European hunter-fisher-gatherer exchange networks, focusing on the Russian Karelian lithic industry. The geographically limited, large-scale production of Russian Karelian artefacts for export testifies to the specialised production of lithic material culture that was exchanged over 1000km from the production workshops. Functioning both as everyday tools and objects of social and ritual engagement, and perhaps even constituting a means of long-distance communication, the Russian Karelian industry finds parallels with the exchange systems of contemporaneous European agricultural populations.


2021 ◽  
Author(s):  
K. Vasu Babu ◽  
Sudipta Das ◽  
Gaurav Varshney ◽  
Gorre Naga Jyothi S ◽  
Boddapati Taraka Phani Madhav

Abstract A tree-shaped graphene based microstrip MIMO antenna for terahertz applications is proposed. The proposed MIMO antenna is designed on a 600×300 µm2 polyimide substrate. The designed MIMO antenna exhibits a wide impedance bandwidth of 88.14% (0.276–0.711 THz) due to the suggested modifications in the antenna configuration. The MIMO design parameters like total active reflection coefficient (TARC), mean effective gain (MEG), envelope correlation coefficient (ECC) and diversity gain (DG), Channel capacity loss (CCL) are evaluated and their values are found within acceptable limits. The proposed MIMO structure offers MEG ≤ -3.0 dB, TARC≤ -10.0 dB, DG≈ 10 dB, CCL < 0.5 bps/Hz/sec and ECC < 0.01 at the resonant frequency. At the resonant frequency, the isolation between the radiating elements of the proposed MIMO is recorded as -52 dB. The variations in operating frequency and S-parameters are also analyzed as a function of the chemical potential (µc) of the graphene material. The parametric analysis, structural design evolution steps, surface current distribution, antenna characteristics parameters and diversity parameters are discussed in detail in this paper. The designed MIMO antenna is suitable for high speed short distance communication, video rate imaging, biomedical imaging, sensing, and security scanning in the THz frequency band.


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