Receiver Distance Research Articles

Spatiotemporal Communication in Artificial Cell Consortia for Dynamic Control of DNA Nanostructures.

The spatiotemporal orchestration of cellular processes is a ubiquitous phenomenon in pluricellular organisms and bacterial communities, where sender cells secrete chemical signals that activate specific pathways in distant receivers. Despite its importance, the engineering and investigation of spatiotemporal communication in artificial cell consortia remains underexplored. In this study, we present spatiotemporal communication between cellular-scale entities acting as both senders and receivers. The transmitted signals are leveraged to elicit conformational alterations within compartmentalized DNA structures. Specifically, sender entities control and generate diffusive chemical signals, namely, variations in pH, through the conversion of biomolecular inputs. In the receiver population, compartmentalized DNA nanostructures exhibit changes in conformation, transitioning between triplex and duplex assemblies, in response to this pH variation. We demonstrate the temporal regulation of activated DNA nanostructures through the coordinated action of two antagonistic sender populations. Furthermore, we illustrate the transient distance-dependent activation of the receivers, facilitated by sender populations situated at defined spatial locations. Collectively, our findings provide novel avenues for the design of artificial cell consortia endowed with programmable spatiotemporal dynamics through chemical communication.

Solutions to muddy (geoacoustic inversion) problems

Waveguide propagation is a ubiquitous topic in ocean acoustics. This presentation focuses on low-frequency (f < 500 Hz) sound propagation in coastal oceans (water depth shallower than 500 m). These environments are highly dynamical and complex, and act as dispersive waveguides, bounded by the sea-surface and the seafloor. The underwater acoustic field can thus be described by a set of modes that propagate with frequency-dependent speeds. Propagation of transient acoustic signals to a distant receiver (range > 1 km) accrues multi-modal dispersion information about the propagation medium. To extract relevant information about the oceanic environment from the acoustic recording, physics-based processing methods must be used. In this presentation, I will briefly review modal propagation and time-frequency analysis. I will then show how these approaches can be combined into a non-linear signal processing method dedicated to extracting modal information from a single receiver: this information is the foundation of a transdimensional inversion method used to characterize the oceanic environment. This method will be used to perform geoacoustic inversion on the New England Mud Patch. Using several datasets collected under different oceanographic conditions, I will notably demonstrate a successful estimation of the seafloor properties, consistent with geophysical core measurements and other inversion studies, even when the water column is dynamical and mostly unknown.

Spherical Random Arrays With Application to Aerial Collaborative Beamforming

Spherical volumetric arrays with randomly distributed elements are studied using geometrical probability theory. The array elements are considered as points of an isotropic homogeneous binomial point process (BPP), randomly located within a 3-D ball. The presented results are based on the distance distribution of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k$ </tex-math></inline-formula> th nearest element from the center of the ball. These elements are assumed to be the randomly distributed nodes of a wireless aerial network that cooperate to produce a beam toward a desired distant receiver. An alternative array elements’ distribution is also examined by placing a constraint to the distance of the farthest element and providing novel results on the average array factor, the average power pattern, and the directivity of the array. The half power beamwidth (HPBW), the peak sidelobe level (SLL), and the location of the peaks and nulls of the power pattern are examined in terms of the number of the array elements and the radius of the sphere. Finally, the impact of the location estimation errors on the performance of open-loop collaborative beamforming is examined both theoretically and using empirical simulation results.

Entangled States Are Harder to Transfer than Product States.

The distribution of entangled states is a key task of utmost importance for many quantum information processing protocols. A commonly adopted setup for distributing quantum states envisages the creation of the state in one location, which is then sent to (possibly different) distant receivers through some quantum channels. While it is undoubted and, perhaps, intuitively expected that the distribution of entangled quantum states is less efficient than that of product states, a thorough quantification of this inefficiency (namely, of the difference between the quantum-state transfer fidelity for entangled and factorized states) has not been performed. To this end, in this work, we consider n-independent amplitude-damping channels, acting in parallel, i.e., each, locally, on one part of an n-qubit state. We derive exact analytical results for the fidelity decrease, with respect to the case of product states, in the presence of entanglement in the initial state, for up to four qubits. Interestingly, we find that genuine multipartite entanglement has a more detrimental effect on the fidelity than two-qubit entanglement. Our results hint at the fact that, for larger n-qubit states, the difference in the average fidelity between product and entangled states increases with increasing single-qubit fidelity, thus making the latter a less trustworthy figure of merit.

Polarization angle dependence of vertically propagating radio-frequency signals in South Polar ice

To better understand the effect of ice properties on the capabilities of radio experiments designed to measure ultra-high energy neutrinos (UHEN), we recently considered the timing and amplitude characteristics of radio-frequency (RF) signals propagating along multi-kilometer, primarily horizontal trajectories through cold Polar ice at the South Pole. That analysis indicated satisfactory agreement with a model of ice birefringence based on ice crystal (cˆ-axis) data culled from the South Pole Ice Core Experiment (SPICE). Here we explore the geometrically complementary case of signals propagating along primarily vertical trajectories, using extant data from the Askaryan Radio Array (ARA) experiment, supplemented by a refined analysis of older RICE experimental data. The timing characteristics of the South Polar data are in general agreement with the same birefringence model, although a several nanosecond discrepancy is found in comparison to Taylor Dome data. Re-analysis of older RICE data also confirm the correlation of signal amplitudes reflected from internal-layers with the direction of ice flow, similar to previous observations made along a traverse from Dome Fuji to the Antarctic coast. These results have two important implications for radio-based UHEN experiments: (i) if birefringence can be locally calibrated, the timing characteristics of signals propagating from neutrino-ice interactions to a distant receiver might be used to infer the distance-to-vertex, which is necessary to estimate the energy of the progenitor neutrino, (ii) the measured reflectivity of internal layers may result in previously-unanticipated backgrounds to UHEN searches, requiring significantly more modeling and analysis.

Information design of matching platforms when user preferences are bidimensional

Companies that provide a two‐sided platform for users to proactively seek a match face great challenges in increasing matching efficiency and ensuring match quality. This paper examines how information designs can be used to improve matching outcomes when users derive utility from a match's vertical attribute (i.e., quality) and its horizontal attribute (i.e., idiosyncratic fit). We consider a game‐theoretic model in which competing senders propose matching requests to competing receivers and users on the two sides are differentiated both horizontally and vertically. We first demonstrate that users' preference for the vertical attribute intensifies competition and hurts matching efficiency, and to avoid competition a sender may switch from a close receiver to a distant receiver even when the weight that he places on a match's horizontal closeness increases. Second, we examine four information designs in which one type of information from one side of the market is withheld. Designs that withhold either side's vertical information increase the number of matches, with the improvement from withholding receivers' information being greater. By contrast, designs that withhold either side's horizontal information can cause all requests to concentrate on one receiver and lead to the most severe match failure. Third, an increase in matching volume comes at the expense of certain users' welfare, as withholding one side's vertical information can hurt not only high‐quality users on both sides but also the low‐quality users on the opposite side. Although withholding one side's horizontal information may increase the matching volume under certain conditions, it can be Pareto dominated by a design that withholds one side's vertical information. Fourth, when strategic user pricing is involved, it not only redistributes user welfare but also corrects for matching distortion. Finally, in contrast to the result when strategic pricing is absent, when strategic pricing is present the platform withholding one side's vertical information can benefit all users on the opposite side, while withholding one side's horizontal information can benefit all users on the same side.

Wind, sea swell, and excitation of atmospheric waveguides by underwater earthquakes

Powerful underwater sources, such as volcano eruptions and large explosions, can generate infrasonic waves, which remain detectable at distant receivers on shore. Evers et al. [Geophys. Res. Lett. 41, 1644–1650 (2014)] described observations of acoustic signals in air from the 2004 Macquarie Ridge submarine earthquake, by the infrasonic array IS05AU of the International Monitoring System. Infrasound propagated in the tropospheric and stratospheric waveguides and was received 1325 km from the epicenter. Specific physical mechanisms of the excitation of guided infrasonic waves by underwater sources are not fully understood. Here, we emphasize the potential role of local meteorological conditions. Scattering of ballistic waves from the earthquake epicenter by wind waves and sea swell on the ocean surface is a potent mechanism of excitation of normal modes in hydroacoustic waveguides (T-waves) [Godin, J. Acoust. Soc. Am. 150, 3999–4017 (2021)]. We investigate the hypothesis that the scattering of ballistic waves at the ocean surface also explains the earthquake excitation of acoustic normal modes in the tropospheric and stratospheric waveguides. Relative significance of the surface scattering and the previously proposed evanescent coupling mechanism is studied as a function of the wind speed, wave frequency, and the source depth.

Amplification of frog calls by reflective leaf substrates: implications for terrestrial and arboreal species

ABSTRACT Signal detection is a fundamental requirement for any communicative interaction. Acoustic signals, however, experience amplitude losses during their transmission through the environment, reducing their detection range. Displaying from sites that increase the amplitude of the sound produced, such as cavities or some reflective surfaces, can improve the detectability of signals by distant receivers. We measured the effect of leaf calling sites on the calls of an arboreal (Hyalinobatrachium fleischmanni) and a leaf-litter specialist (Silverstoneia flotator) frog species. We collected the leaves where males of both species were observed calling, and conducted playback experiments to measure their effect on the amplitude of frog calls. Overall, the leaves used by H. fleischmanni and S. flotator were of similar dimensions, and amplified the calls of each species by about 5.0 and 2.5 dB, respectively. The degree of call amplification was unrelated to leaf dimensions or the position of the frogs on the leaves, but explained by the different frequency content of the calls of each species. We suggest that amplification of frogs calls by leaves could represent either a benefit or impose costs for arboreal and terrestrial species, which may depend on the spatial location of intended and unintended receivers.

Active Radar Cross Section Reduction of an Object Using Microstrip Antennas

AbstractThe research performed in this paper suggests that the radar cross section of an arbitrarily shaped object can be reduced by canceling the scattering from the object with the radiation from an antenna (implemented here as a microstrip antenna) placed on the surface of the object. Assuming that the direction of arrival of the incident signal is known, the radiation from the defending antenna can be adjusted in real‐time to cancel the scattering from the object in order to produce a negligible total field at the distant receiver so that the object becomes invisible to a monostatic radar working in a given known frequency band. This is implemented using an analog sensor on the object to measure the time domain field on the object, which is then connected to the antenna through an amplifier and phase shifter to control the radiation from the patch antenna. The system is implemented in real time and does not require any digitization or signal processing. The radar cross section reduction can thus be achieved with a wide variety of incident signals in the prescribed frequency band.

Spin chains for two-qubit teleportation

Generating high-quality multi-particle entanglement between communicating parties is the primary resource in quantum teleportation protocols. To this aim, we show that the natural dynamics of a single spin chain is able to sustain the generation of two pairs of Bell states - possibly shared between a sender and a distant receiver - which can in turn enable two-qubit teleportation. In particular, we address a spin-1/2 chain with XX interactions, connecting two pairs of spins located at its boundaries, playing the roles of sender and receiver. In the regime where both end pairs are weakly coupled to the spin chain, it is possible to generate at predefinite times a state that has vanishing infidelity with the product state of two Bell pairs, thereby providing nearly unit fidelity of teleportation. We also derive an effective Hamiltonian via a second-order perturbation approach that faithfully reproduces the dynamics of the full system.

A Simplified Form of Beam Spread Function in Underwater Wireless Optical Communication and its Applications

Underwater wireless optical communication (UWOC) refers to the transmission of data in unguided water medium through optical carriers. Beam spread function (BSF) characterizes the amount of light irradiance received at the receiver as a function of receiver's distance from main beam axis for a particular link length. The existing form of BSF includes multiple integrals which are burdensome to use for mathematical analysis. Because of this, it gets very difficult to employ the existing form of BSF to derive non-integral expressions for bit error rate (BER), capacity, and outage probability of UWOC systems. Moreover, it is very difficult to find any insight into the UWOC systems based on this integral form of BSF. In this paper, we derive a simplified power series expression of BSF by solving the existing integral form. Closed-form expressions of BSF with some approximations, which simplify the derived power series expression, are also provided as special cases. Important insights regarding the behavior of BSF are also obtained from the derived simplified forms. Furthermore, closed-form expressions of BER, capacity, and outage probability of the UWOC system, taking the effect of scattering, absorption, and misalignment in consideration, are also derived.

Communication Cost for Updating Linear Functions When Message Updates are Sparse: Connections to Maximally Recoverable Codes

We consider a communication problem in which an update of the source message needs to be conveyed to one or more distant receivers that are interested in maintaining specific linear functions of the source message. The setting is one in which the updates are sparse in nature, and where neither the source nor the receiver(s) is aware of the exact {\em difference vector}, but only know the amount of sparsity that is present in the difference-vector. Under this setting, we are interested in devising linear encoding and decoding schemes that minimize the communication cost involved. We show that the optimal solution to this problem is closely related to the notion of maximally recoverable codes (MRCs), which were originally introduced in the context of coding for storage systems. In the context of storage, MRCs guarantee optimal erasure protection when the system is partially constrained to have local parity relations among the storage nodes. In our problem, we show that optimal solutions exist if and only if MRCs of certain kind (identified by the desired linear functions) exist. We consider point-to-point and broadcast versions of the problem, and identify connections to MRCs under both these settings. For the point-to-point setting, we show that our linear-encoder based achievable scheme is optimal even when non-linear encoding is permitted. The theory is illustrated in the context of updating erasure coded storage nodes. We present examples based on modern storage codes such as the minimum bandwidth regenerating codes.

Robust Transmissions in Wireless-Powered Multi-Relay Networks With Chance Interference Constraints

In this paper, we consider a wireless powered multi-relay network in which a multi-antenna hybrid access point underlaying a cellular system transmits information to distant receivers. Multiple relays capable of energy harvesting are deployed in the network to assist the information transmission. The hybrid access point can wirelessly supply energy to the relays, achieving multi-user gains from signal and energy cooperation. We propose a joint optimization for signal beamforming of the hybrid access point as well as wireless energy harvesting and collaborative beamforming strategies of the relays. The objective is to maximize network throughput subject to probabilistic interference constraints at the cellular user equipment. We formulate the throughput maximization with both the time-switching and power-splitting schemes, which impose very different couplings between the operating parameters for wireless power and information transfer. Although the optimization problems are inherently non-convex, they share similar structural properties that can be leveraged for efficient algorithm design. In particular, by exploiting monotonicity in the throughput, we maximize it iteratively via customized polyblock approximation with reduced complexity. The numerical results show that the proposed algorithms can achieve close to optimal performance in terms of the energy efficiency and throughput.

Contribution of auxiliary coherent radar receiver to target's velocity estimation

Recent progress in bistatic radar techniques can be used to improve performances of classical monostatic radar. A prominent limitation of coherent radar is its inability to measure the complete velocity vector (magnitude and direction) of a detected target. A single coherent detection can provide range-rate only. At least two detections, separated in time, are needed to estimate the target's velocity vector. This study discusses how the velocity vector can be determined by two simultaneous detections spaced in distance. The second detection is obtained by an auxiliary distant bistatic coherent receiver; an approach proposed in the 1990s to enhance meteorological radar. Being a very simple case of a distributed radar system allows for a simple demonstration of how to calculate the target's position and velocity vector and how to analyse the estimation accuracy, including geometric dilution of precision plots of the velocity error. Also discussed are two methods to identify correct data association when more than one target is detected.

Probabilistic Broadcast-Based Multiparty Remote State Preparation scheme via Four-Qubit Cluster State

In this letter,we propose a broadcast-based multiparty remote state preparation scheme which realizes the process among three participants. It allows two distant receivers to obtain the arbitrary single-qubit states separately and simultaneously, and the success probability is $\frac {d^{2}}{1+d^{2}}$ , thus generalize the results in Yu et al. (Quantum. Inf. Process 16(2), 41, 2017).

Optical Axis Identification Technique for Free Space Optics Transmission

This paper describes optical axis adjustment technique for an active free space optics transmission system. This system precisely controls the direction of a collimated thin laser beam using a motor driven laser emitting mechanism and positioning photodiodes. Before beginning laser beam feedback control, it is required to guide the laser beam within the range of the positioning photodiodes for initial laser beam alignment. This paper proposes an arrival position presumption method of laser beam traveling along the long distance from transmitter. A positioning sensor containing several photodiodes measures laser luminescence distribution, and analytically calculates the optical axis of laser beam according to the modified Gaussian beam optics based on four or five distributed local intensity of laser luminescence. Experiments are conducted to evaluate the accuracy of the presumption, and results reveal that the method is effective in leading the laser beam onto a distant receiver.

The ecoacoustics of a kelp forest: Measurement and prediction (Ecklonia radiata)

Despite of over a century of intensive research on kelp (brown macroalgae of the order Laminariales), very few acoustic studies have been undertaken and much remains unknown about their species-specific acoustic properties, which are nevertheless essential for surveying and managing the respective habitats. In this paper, we discuss results of an in-situ, acoustic and ecological investigation of species Ecklonia radiata which forms dense aggregations at Canoe bay, Tasmania (FORTES 12). The experiment measured extensively the time‐varying Green’s function (0.2–20 kHz) between pairs of distant source and receivers together with physical and biogeochemical variables of the ecosystem. Propagation and scattering features are interpreted in the light of other results obtained by the authors including ray-based estimation of the channel impulse response envelope, finite‐element scattering model of a whole E. radiata thallus, and a study of production from diel oxygen modelling, oxygen exchange, and electron tran...

Gliding lizards use the position of the sun to enhance social display.

Effective communication requires animal signals to be readily detected by receivers in the environments in which they are typically given. Certain light conditions enhance the visibility of colour signals and these conditions can vary depending on the orientation of the sun and the position of the signaller. We tested whether Draco sumatranus gliding lizards modified their position relative to the sun to enhance the conspicuousness of their throat-fan (dewlap) during social display to conspecifics. The dewlap was translucent, and we found that lizards were significantly more likely to orient themselves perpendicular to the sun when displaying. This increases the dewlap's radiance, and likely, its conspicuousness, by increasing the amount of light transmitted through the ornament. This is a rare example of a behavioural adaptation for enhancing the visibility of an ornament to distant receivers.

Quantum broadcast scheme and multi-output quantum teleportation via four-qubit cluster state

In this paper, two theoretical schemes of the arbitrary single-qubit states via four-qubit cluster state are proposed. One is three-party quantum broadcast scheme, which realizes the broadcast among three participants. The other is multi-output quantum teleportation. Both allow two distant receivers to simultaneously and deterministically obtain the arbitrary single-qubit states, respectively. Compared with former schemes of an arbitrary single-qubit state, the proposed schemes realize quantum multi-cast communication efficiently, which enables Bob and Charlie to obtain the states simultaneously in the case of just knowing Alice's measurement results. The proposed schemes play an important role in quantum information, specially in secret sharing and quantum teleportation.

Speeding up transmissions of unknown quantum information along Ising-type quantum channels**Project partly supported by the National Natural Science Foundation of China (Grant No. U1330201).

Quantum teleportation with entanglement channels and a series of two-qubit SWAP gates between the nearest-neighbor qubits are usually utilized to achieve the transfers of unknown quantum state from the sender to the distant receiver. In this paper, by simplifying the usual SWAP gates we propose an approach to speed up the transmissions of unknown quantum information, specifically including the single-qubit unknown state and two-qubit unknown entangled ones, by a series of entangling and disentangling operations between the remote qubits with distant interactions. The generic proposal is demonstrated specifically with experimentally-existing Ising-type quantum channels without transverse interaction; liquid NMR-molecules driven by global radio frequency electromagnetic pulses and capacitively-coupled Josephson circuits driven by local microwave pulses. The proposal should be particularly useful to set up the connections between the distant qubits in a chip of quantum computing.