Intercontinental Distances Research Articles

Suppressing internet bottleneck with Kudryashov’s extended version of self-phase modulation and fractional temporal evolution

AbstractThe current paper employs Kudryashov’s approach to suppress Internet bottleneck effect for the model with factional temporal evolution, linear chromatic dispersion and Kudryahov’s proposed form of extended self-phase modulation with power-law embedded in it. Kudryasov’s approach to integration yielded soliton solutions that is used to transmit solitons across intercontinental distances with a controlled speed which can regulate the internet traffic flow.

The ideal wavelength for daylight free-space quantum key distribution

Quantum key distribution (QKD) has matured in recent years from laboratory proof-of-principle demonstrations to commercially available systems. One of the major bottlenecks is the limited communication distance in fiber networks due to the exponential signal damping. To bridge intercontinental distances, low Earth orbit satellites transmitting quantum signals over the atmosphere can be used. These free-space links, however, can only operate during the night, as the sunlight otherwise saturates the detectors used to measure the quantum states. For applying QKD in a global quantum internet with continuous availability and high data rates, operation during daylight is required. In this work, we model a satellite-to-ground quantum channel for different quantum light sources to identify the optimal wavelength for free-space QKD under ambient conditions. Daylight quantum communication is possible within the Fraunhofer lines or in the near-infrared spectrum, where the intrinsic background from the sun is comparably low. The highest annual secret key length considering the finite key effect is achievable at the Hα Fraunhofer line. More importantly, we provide the fundamental model that can be adapted, in general, to any other specific link scenario taking into account the required modifications. We also propose a true single-photon source based on a color center in hexagonal boron nitride coupled to a microresonator that can implement such a scheme. Our results can also be applied in roof-to-roof scenarios and are, therefore, relevant for near-future quantum networks.

The Coming Hypersonic Era

Much of the literature on emerging hypersonic weapons discusses their ability to deliver strategic nuclear strikes, conduct nuclear counterforce, or perform traditional tactical strikes in isolation. However, with their inherent versatility, a single hypersonic weapon can perform all of these roles without reconfiguration. I explain how the versatility of these new multipurpose weapons generates ambiguity and undermines the tenets of nuclear deterrence theory. National leaders who observe HPGM deployments on their nations’ borders will increasingly view HPGM weapons as tools of destabilizing counterforce, even if the deployers have defensive intentions. With HPGMs capable of traveling inter-continental distances on the horizon, policies of restraint will become necessary to clearly indicate intentions without increasing global fear of counterforce strikes.

Resource-efficient fault-tolerant one-way quantum repeater with code concatenation

One-way quantum repeaters where loss and operational errors are counteracted by quantum error-correcting codes can ensure fast and reliable qubit transmission in quantum networks. It is crucial that the resource requirements of such repeaters, for example, the number of qubits per repeater node and the complexity of the quantum error-correcting operations are kept to a minimum to allow for near-future implementations. To this end, we propose a one-way quantum repeater that targets both the loss and operational error rates in a communication channel in a resource-efficient manner using code concatenation. Specifically, we consider a tree-cluster code as an inner loss-tolerant code concatenated with an outer 5-qubit code for protection against Pauli errors. Adopting flag-based stabilizer measurements, we show that intercontinental distances of up to 10,000 km can be bridged with a minimized resource overhead by interspersing repeater nodes that each specialize in suppressing either loss or operational errors. Our work demonstrates how tailored error-correcting codes can significantly lower the experimental requirements for long-distance quantum communication.

Exploration of interactional phenomena and multi‐wave solutions of the fractional‐order dual‐mode nonlinear Schrödinger equation

This work concerns the fractional‐order dual‐mode nonlinear Schrödinger equation (FDMNLSE), which portrays the augmentation or absorption of dual waves. This model dissects the concurrent generation of two characteristic waves dealing with dual modes and introduces three physical parameters: nonlinearity, phase velocity, and dispersive factor. In the context of photonics, NLSE models the propagation of soliton pulses over intercontinental distances. Throughout this work, the fractional derivative is given in terms of time and space conformable sense. We analyze the multi‐waves method, homoclinic breather approach, and interactional solution with the double ‐functions procedure, and their applications for this equation are obtained using logarithmic transformation. The multi‐wave method is a well‐known phenomenon in nonlinear science that describes the interaction of three waves that satisfy certain resonance conditions. A breather wave is a localized and oscillatory solution that maintains its shape over time. Finally, we will discuss the dynamics of our newly obtained solutions with the help of graphs by assigning appropriate values to the parameters. The proposed methods are straight and aggressive, so the approved form can be extended for more nonlinear models. The findings are exceptional in comparison to previous findings in the literature. These outcomes may have significance for additional investigation of such frameworks to handle the nonlinear issues in applied sciences. The obtained results help us understand fluid propagation and incompressible fluids.

Chirped optical solitons and stability analysis of the nonlinear Schrödinger equation with nonlinear chromatic dispersion

The present paper aims to investigate the chirped optical soliton solutions of the nonlinear Schrödinger equation with nonlinear chromatic dispersion and quadratic-cubic law of refractive index. The exquisite balance between the chromatic dispersion and the nonlinearity associated with the refractive index of a fiber gives rise to optical solitons, which can travel down the fiber for intercontinental distances. The effective technique, namely, the new extended auxiliary equation method is implemented as a solution method. Different types of chirped soliton solutions including dark, bright, singular and periodic soliton solutions are extracted from the Jacobi elliptic function solutions when the modulus of the Jacobi elliptic function approaches to one or zero. These obtained chirped optical soliton solutions might play an important role in optical communication links and optical signal processing systems. The stability of the system is examined in the framework of modulational instability analysis.

Airborne microbiomes at a subtropical island in southern China: Importance of the northwest and southeast monsoons

Airborne microbes can survive in the atmosphere, travel intercontinental distances by air mass movement, and colonize in remote area through dry and wet deposition, thus forming a connection between oceanic, atmospheric, and terrestrial systems. However, studies linking the monsoon and bioaerosol transport are extremely rare. Here we applied high-throughput sequencing to investigate airborne microbial community succession on an island in Pearl River Estuary under summer and winter monsoon influence. The microbial communities from local potential sources (i.e., soil, leaf and surface seawater), water-soluble ions, organic carbon and elemental carbon were used to evaluate marine and terrestrial contribution. Our results revealed that airborne microbial communities underwent rapid changes during different monsoons influence (ANOSIM, P < 0.005), especially fungal aerosol. Fungal aerosols were dominant by Cladosporium, Debaryomyces, Rhodotorula, Fusarium, Aureobasidium and Candida during winter monsoon, while Coriolopsis, Ceriporia, Fomes, Phanerochaete, Trametes, Phlebia, and Antrodia were predominant fungal genera during summer monsoon. Redundant analysis showed that changes of air temperature and relative humidity caused by monsoon were the most important driven factors of airborne microbial communities in summer monsoon for airborne microbial communities. In addition, terrestrial sources were the most important contribution, especially that of soil for airborne bacteria. Some taxa were affected by atmospheric transport influenced by monsoon synoptic air mass movement.

Dual-mode nonlinear Schrödinger equation (DMNLSE): Lie group analysis, group invariant solutions, and conservation laws

This paper proposed a novel dual-mode nonlinear Schrödinger equation (DMNLSE) with cubic law. The DMNLSE describes the propagations of two moving waves simultaneously. This nonlinear Schrödinger equation (NLSE) model appears in different areas of physics, including nonlinear optics, plasma physics, superconductivity, and quantum mechanics. In the context of photonics, NLSE models the propagation of soliton pulses through inter-continental distances. In this study, the Lie symmetry procedure is successfully utilized on the DMNLSE to discover the infinitesimal generators using the invariance condition. Then, we transform the DMNLSE into an ordinary differential equation (ODE) employing accepted generators and similarity reduction concepts. Later, we consider conservation laws for the DMNLSE. Thanks to the multiplier technique, the conserved quantities’ densities and fluxes are discovered. With the aid of the Mathematica package program, 3D, contour, and density graphs were drawn for the special values of the parameters in the solutions, and the physical structures of the solutions obtained in this way were also observed.

Cubic-Quartic Optical Solitons in Fiber Bragg Gratings with Dispersive Reflectivity Having Parabolic Law of Nonlinear Refractive Index by Lie Symmetry

This work recovers cubic-quartic optical solitons with dispersive reflectivity in fiber Bragg gratings and parabolic law of nonlinearity. The Lie symmetry analysis first reduces the governing partial differential equations to the corresponding ordinary differential equations which are subsequently integrated. This integration is conducted using two approaches which are the modified Kudryashov’s approach as well as the generalized Arnous’ scheme. These collectively yielded a full spectrum of cubic-quartic optical solitons that have been proposed to control the depletion of the much-needed chromatic dispersion. They range from bright, dark, singular to combo solitons. These solitons are considered with dispersive reflectivity, which maintains the necessary balance between chromatic dispersion and nonlinear refractive index structure for an uninterrupted transmission of solitons along intercontinental distances. Their respective surface and contour plots are also exhibited. A few closing words are included with some prospective future avenues of research to extend this topic further.

Evaluation of 137Cs, 133Xe and 3H activity concentrations monitored in the Arctic atmosphere

This paper provides a brief introduction to the Arctic atmospheric radioactivity monitoring network. A decade of monitoring results have shown the 137Cs background levels in Arctic air range from 0.05 to 1.50 μBq/m3. The monitoring stations have sufficient sensitivity to detect 137Cs brought to the atmosphere due to resuspension in local soil and reemissions from biomass burning in a daily temporal resolution. These observations can be used as tracers for atmospheric processes. The 133Xe measurements obtained at Yellowknife, Resolute and Spitsbergen could support other research into how air pollution problems arise across intercontinental distances. It will help develop and improve models capable of predicting the long-distance transport and deposition of trace gases in the Arctic. Rainwater monitoring data collected in Finnish Lapland since the 1960's indicate that 3H radioactivity concentrations reached natural background levels in early 2000s, typically around 1–2 Bq/L monthly, with an annual seasonal variation cycle consistent with the observed of other cosmogenic radionuclides.

Analysis in fiber Bragg gratings with Kerr law nonlinearity for diverse optical soliton solutions by reliable analytical techniques

This paper reveals optical soliton solutions to fiber Bragg gratings (FBGs) with dispersive reflectivity having Kerr law of nonlinear refractive index. Bragg gratings are no doubt a technological spectacle that sustained balance between dispersion and the nonlinear effects that leads to a stable transmission of solitons across intercontinental distances. FBGs as sensor elements are used for measuring numerous engineering parameters such as temperature, strain, pressure, tilt, displacement, acceleration, load. Two recently developed mechanisms such as the unified method and extended sinh-Gordon equation expansion method (ShGEEM) are successfully employed to secure optical pulses in the shapes of the bright, dark, singular, complex combo, periodic, and plane wave solutions. The achieved solutions contain key applications in engineering and physics. These solutions define the wave performance of the governing models. By selecting suitable parametric values, the dynamics of the evaluated results are exemplified by sketching their 2-dimensional, 3-dimensional, and contour profiles to understand the real phenomena for such sort of nonlinear models. The novelty of the gained outcomes is manifested by a detailed comparison with the results that already exist.

Highly dispersive optical and other soliton solutions to fiber Bragg gratings with the application of different mechanisms

This work devotes to explore abundant optical and other soliton solutions to fiber Bragg gratings with dispersive reflectivity having Kerr law of nonlinear refractive index. Bragg gratings are no doubt a technological spectacle that sustained balance between dispersion and nonlinear effects that leads to a stable transmission of solitons across intercontinental distances. Three reliable integration norms namely ([Formula: see text])-expansion function method, generalized tanh method and generalized Kudryashov method are engaging to devise optical dark, singular, combo, complex and periodic solutions. The reported solutions contain key applications in engineering and physics. These solutions define the wave performance of the governing models, actually. By the choice of suitable parametric values, the dynamics of the evaluated results are exemplified by sketching their 2D, 3D and contour profiles to understand the real phenomena for such sort of nonlinear models. The novelty of the gained outcomes is manifested by a detailed comparison with the results that already exist. The outcomes disclose that our schemes are very active reliable, concise, outspoken, appropriate, useful and skilled for attaining the exact solutions of such kind of problems which minimize the computational work and give it a wide range of applications.

Prospects and challenges of the liquefied natural gas market in Brazil

The liquefied natural gas can overcome current barriers, mainly for natural gas transportation over long distances, enabling global trade and overcoming intercontinental distances. Following this trend, Brazil is entering this global market for liquefied natural gas. Therefore, this study aims to evaluate the prospects and challenges of liquefied natural gas for the Brazilian natural gas market through reports from the government and the national industry. It was possible to identify the strengths, weaknesses, opportunities, and threats (SWOT) of this natural gas supply option within the national matrix through the SWOT analysis. After this, the gravity, urgency, and tendency (GUT) matrix were applied and adapted to classify just one dimension, as the importance of each point of the SWOT. As a result, substantial material was gathered for analysis demonstrating positive and negative characteristics of liquefied natural gas for Brazil, besides the government's view on the subject, which can be useful mainly for the academic, commercial, and industrial.

Including precision clocks into space-based net as gravitational antennas

Here we propose to use a precision clock in a space-based ultra-precise clock network to register sources of low-frequency gravitational waves of cosmic origin in the range of 10-3 ÷ 0.1 Hz. We also show that the method of comparing clocks at inland and intercontinental distances (very long baseline interferometry), originally developed for radio astronomy and geodesy, can be used as a prototype method for recording gravitational waves. Estimates of the measurement accuracy are given. An analyse of precise clocks possibilities for experimental estimates for rotation parameter of Gödel universe and GW recordings is offered, which in particular opens up the prospect of registering circularly polarized gravitational waves. Some new problems of small time intervals registration from general relativity, thermodynamics and quantum mechanics points of view are discussed.

General decline in the diversity of the airborne microbiota under future climatic scenarios

Microorganisms attached to aerosols can travel intercontinental distances, survive, and further colonize remote environments. Airborne microbes are influenced by environmental and climatic patterns that are predicted to change in the near future, with unknown consequences. We developed a new predictive method that dynamically addressed the temporal evolution of biodiversity in response to environmental covariates, linked to future climatic scenarios of the IPCC (AR5). We fitted these models against a 7-year monitoring of airborne microbes, collected in wet depositions. We found that Bacteria were more influenced by climatic variables than by aerosols sources, while the opposite was detected for Eukarya. Also, model simulations showed a general decline in bacterial richness, idiosyncratic responses of Eukarya, and changes in seasonality, with higher intensity within the worst-case climatic scenario (RCP 8.5). Additionally, the model predicted lower richness for airborne potential eukaryotic (fungi) pathogens of plants and humans. Our work pioneers on the potential effects of environmental variability on the airborne microbiome under the uncertain context of climate change.

Atmospheric refraction corrections in ground-to-satellite optical time transfer.

Free-space optical time and frequency transfer techniques can synchronize fixed ground stations at the femtosecond level, over distances of tens of kilometers. However, optical time transfer will be required to span intercontinental distances in order to truly unlock the performance of optical frequency standards and support an eventual redefinition of the SI second. Fiber dispersion and Sagnac uncertainty severely limit the performance of long-range optical time transfer over fiber networks, so satellite-based free-space time transfer is a promising solution. In pursuit of ground-to-space optical time transfer, previous work has considered a number of systematic shifts and concluded that all of them are manageable. One systematic effect that has not yet been substantially studied in the context of time transfer is the effect of excess optical path length due to atmospheric refraction. For space-borne objects, orbital motion causes atmospheric refraction to be imperfectly canceled even by two-way time and frequency transfer techniques, and so will require a temperature-, pressure-, and humidity-dependent correction. This systematic term may be as large as a few picoseconds at low elevations and remains significant at elevations up to ~35°. It also introduces biases into previously-studied distance- and velocity-dependent corrections.

Моделирование температурного состояния образцов высокотемпературных керамических материалов

Developing high-velocity atmospheric aircraft equipped with ramjet engines, which use atmospheric air as the oxidizer, is an important component of aerospace technology prospects. These craft may be employed to quickly deliver payloads over intercontinental distances and as boosters for spacecraft injection into orbit. A characteristic feature of high-velocity atmospheric aircraft is a presence of sharp aerofoil edges subjected to highly oxidative airflow. This means that actual implementation of numerous hypersonic atmospheric aircraft projects largely depends on whether it is possible to develop materials that could remain stable in an oxidative atmosphere at temperatures of 2000--2500 °C. We estimated the thermal state of a structural component in the shape of a blunted wedge made out of promising refractory ceramics under flight conditions at an altitude of 22 km and a velocity of Mach 7

A broadband VLBI system using transportable stations for geodesy and metrology: an alternative approach to the VGOS concept

We have developed a broadband VLBI (very long baseline interferometry) system inspired by the concept of the VLBI Global Observing System (VGOS). The new broadband VLBI system was implemented in the Kashima 34 m antenna and in two transportable stations utilizing 2.4 m diameter antennas. The transportable stations have been developed as a tool for intercontinental frequency comparison but are equally useful for geodesy. To enable practical use of such small VLBI stations in intercontinental VLBI, we have developed the procedure of node-hub style VLBI: In joint observation with a large, high sensitivity ‘hub’ antenna, the closure delay relation provides a virtual delay observable between ‘node’ stations. This overcomes the limited sensitivity of the small diameter node antennas, while error sources associated with large diameter antennas, such as gravitational deformation and delay changes in necessarily long signal cables, are eliminated. We show that this scheme does not result in an increased sensitivity to radio source structure if one side of the baseline triangle is kept short. We have performed VLBI experiments utilizing this approach over both short range and intercontinental distance. This article describes the system components, signal processing procedure, experiment, and results in terms of baseline repeatability. Our measurements reveal signatures of structure effects in the correlation amplitude of several of the observed radio sources. We present a model of the frequency-dependent source size for 1928+738 derived from correlation amplitude data observed in four frequency bands.

Re-Invasion of H5N8 High Pathogenicity Avian Influenza Virus Clade 2.3.4.4b in Hokkaido, Japan, 2020.

Global dispersion of high pathogenicity avian influenza (HPAI), especially that caused by H5 clade 2.3.4.4, has threatened poultry industries and, potentially, human health. An HPAI virus, A/northern pintail/Hokkaido/M13/2020 (H5N8) (NP/Hok/20) belonging to clade 2.3.4.4b, was isolated from a fecal sample collected at a lake in Hokkaido, Japan where migratory birds rested, October 2020. In the phylogenetic trees of all eight gene segments, NP/Hok/20 fell into in the cluster of European isolates in 2020, but was distinct from the isolates in eastern Asia and Europe during the winter season of 2017–2018. The antigenic cartography indicates that the antigenicity of NP/Hok/20 was almost the same as that of previous isolates of H5 clade 2.3.4.4b, whereas the antigenic distances from NP/Hok/20 to the representative strains in clade 2.3.4.4e and to a strain in 2.3.4 were apparently distant. These data imply that HPAI virus clade 2.3.4.4b should have been delivered by bird migration despite the intercontinental distance, although it was not defined whether NP/Hok/20 was transported from Europe via Siberia where migratory birds nest in the summer season. Given the probability of perpetuation of transmission in the northern territory, periodic updates of intensive surveys on avian influenza at the global level are essential to prepare for future outbreaks of the HPAI virus.

Clock comparison using black holes

Observing accreting black holes in the early Universe allows precise comparison of clocks over intercontinental distances on Earth. This is achieved with a novel observation strategy using the next generation of very long baseline interferometry systems.