Target Detection Range Research Articles

Benchmarking automation-aided performance in a forensic face matching task

Carragher and Hancock (2023) investigated how individuals performed in a one-to-one face matching task when assisted by an Automated Facial Recognition System (AFRS). Across five pre-registered experiments they found evidence of suboptimal aided performance, with AFRS-assisted individuals consistently failing to reach the level of performance the AFRS achieved alone. The current study reanalyses these data (Carragher and Hancock, 2023), to benchmark automation-aided performance against a series of statistical models of collaborative decision making, spanning a range of efficiency levels. Analyses using a Bayesian hierarchical signal detection model revealed that collaborative performance was highly inefficient, falling closest to the most suboptimal models of automation dependence tested. This pattern of results generalises previous reports of suboptimal human-automation interaction across a range of visual search, target detection, sensory discrimination, and numeric estimation decision-making tasks. The current study is the first to provide benchmarks of automation-aided performance in the one-to-one face matching task.

TRENDS OF THE MICROWAVE PHOTONIC RADARS

Today, the world's leading countries are intensively working on the development of new generation radars - microwave photonic radars. Microwave photonic radars make it possible to significantly reduce the mass and size characteristics of radar stations, to increase the information capability and range of target detection due to the reduction of losses in long communication lines when using optical fiber, to ensure high immunity due to the significantly lower sensitivity of optical-electronic equipment and fiber-optic lines of communication connection to external electromagnetic influences. Microwave photonics provides wide bandwidth, flat response, low loss transmission, multi-dimensional multiplexing, ultra-fast analog signal processing and immunity to electromagnetic interference. Radar implementation in the optical domain can provide better resolution, coverage, and speed performance, which would be difficult to implement with traditional electronics. The review article examines the state of development and system architectures of such photonic radars as optoelectronic hybrid radars, all-optical radars, multifunctional microwave photonic radar systems, distributed microwave photonic radars, software-defined radars, and cognitive radars. New technologies in this field and possible future directions of research are discussed. As an example, a broadband microwave photon radar reproduced on the basis of a microcircuit is considered. The broadband signal generator and receiver are built into the silicon crystal on the insulator. A high-precision distance measurement with a resolution of 2.7 cm and an error of less than 2.75 mm was obtained. Visualization of multiple targets with complex profiles has been implemented. But the performance of most integrated microwave photonic chips is not yet satisfactory for practical radar applications. Monolithic integration of key microwave photonic subsystems is also not mature enough for practical applications, so hybrid integration of devices fabricated on their optimal integration platforms is of practical interest. At present, indium phosphide, silicon nitride and silicon on insulator are the three leading platforms for photonic integration

Frameshift mutations in peripheral blood as a biomarker for surveillance of Lynch syndrome.

Lynch syndrome is a hereditary cancer predisposition syndrome caused by germline mutations in DNA mismatch repair genes, which lead to high microsatellite instability and frameshift mutations at coding mononucleotide repeats in the genome. Recurrent frameshift mutations in these regions are thought to play a central role in the increased risk of various cancers, but no biomarkers are currently available for the surveillance of high microsatellite instability-associated cancers. A frameshift mutation-based biomarker panel was developed and validated by targeted next-generation sequencing of supernatant DNA from cultured high microsatellite instability colorectal cancer cells. This panel supported selection of 122 frameshift mutation targets as potential biomarkers. This biomarker panel was then tested using matched tumor, adjacent normal tissue, and buffy coat samples (53 samples) and blood-derived cell-free DNA (cfDNA) (38 samples) obtained from 45 high microsatellite instability and mismatch repair-deficient patients. We also sequenced cfDNA from 84 healthy participants to assess background noise. Recurrent frameshift mutations at coding mononucleotide repeats were detectable not only in tumors but also in cfDNA from high microsatellite instability and mismatch repair-deficient patients, including a Lynch syndrome carrier, with a varying range of target detection (up to 85.2%), whereas they were virtually undetectable in healthy participants. Receiver operating characteristic curve analysis showed high sensitivity and specificity (area under the curve = 0.94) of the investigated panel. We demonstrated that frameshift mutations can be detected in cfDNA from high microsatellite instability and mismatch repair-deficient patients and asymptomatic carriers. The 122-target frameshift mutation panel described here has promise as a tool for improved surveillance of high microsatellite instability and mismatch repair-deficient patients, with the potential to reduce the frequency of invasive screening methods for this high-cancer-risk cohort.

DNA and Nanomaterials: A Functional Combination for DNA Sensing.

Recent decades have experienced tough situations due to the lack of reliable diagnostic facilities. The most recent cases occurred during the pandemic, where researchers observed the lack of diagnostic facilities with precision. Microorganisms and viral disease's ability to escape diagnosis has been a global challenge. DNA always has been a unique moiety with a strong and precise base-paired structure. DNA in human and foreign particles makes identification possible through base pairing. Since then, researchers have focused heavily on designing diagnostic assays targeting DNA in particular. Moreover, DNA nanotechnology has contributed vastly to designing composite nanomaterials by combining DNA/nucleic acids with functional nanomaterials and inorganic nanoparticles exploiting their physicochemical properties. These nanomaterials often exhibit unique or enhanced properties due to the synergistic activity of the many components. The capabilities of DNA and additional nanomaterials have shown the combination of robust and advanced tailoring of biosensors. Preceding findings state that the conventional strategies have exhibited certain limitations such as a low range of target detection, less biodegradability, subordinate half-life, and high susceptibility to microenvironments; however, a DNA-nanomaterial-based biosensor has overcome these limitations meaningfully. Additionally, the unique properties of nucleic acids have been studied extensively due to their high signal conduction abilities. Here, we review recent studies on DNA-nanomaterial-based biosensors, their mechanism of action, and improved/updated strategies in vivo and in situ. Furthermore, this review highlights the recent methodologies on DNA utilization to exploit the interfacial properties of nanomaterials in DNA sensing. Lastly, the review concludes with the limitations/challenges and future directions.

Surface functionalization of a chalcogenide IR photonic sensor by means of a polymer membrane for water pollution remediation.

Rapid, simultaneous detection of organic chemical pollutants in water is an important issue to solve for protecting human health. This study investigated the possibility of developing an in situ reusable optical sensor capable of selective measurements utilizing a chalcogenide transducer supplemented by a hydrophobic polymer membrane with detection based on evanescent waves in the mid-infrared spectrum. In order to optimise a polyisobutylene hydrophobic film deposited on a chalcogenide waveguide, a zinc selenide prism was utilized as a testbed for performing attenuated total reflection with Fourier-transform infrared spectroscopy. To comply with the levels mentioned in health guidelines, the target detection range in this study was kept rather low, with the concentration range extended from 50 ppb to 100 ppm to cover accidental pollution problems, while targeted hydrocarbons (benzene, toluene, and xylene) were still detected at a concentration of 100 ppb. Infrared measurements in the selected range showed a linear behaviour, with the exception of two constantly reproducible plateau phases around 25 and 80 ppm, which were observable for two polymer film thicknesses of 5 and 10 μm. The polymer was also found to be reusable by regenerating it with water between individual measurements by increasing the water temperature and flow to facilitate reverse exchange kinetics. Given the good conformability of the hydrophobic polymer when coated on chalcogenide photonic circuits and its demonstrated ability to detect organic pollutants in water and to be regenerated afterwards, a microfluidic channel utilising water flow over an evanescent wave optical transducer based on a chalcogenide waveguide and a polyisobutylene (PIB) hydrophobic layer deposited on its surface was successfully fabricated from polydimethylsiloxane by filling a mold prepared via CAD and 3D printing techniques.

Multi-passive coherent location radar system for detection range and range-doppler resolution in Tarakan

The presence of many radio frequency illuminators in an area provides an opportunity to be used as a transmission source for a passive radar system called a passive coherent locator (PCL). Unlike the active radar, the passive radar provides advantages such as low cost without an active transmitter, potential for broad range measurements, portable in construction, anti-detectable by active radar or electronic counter measures (ECM), etc. Just like other areas where there are many PCL in Tarakan such as FM radio transmission (RRI), many base-stations (BTS) from 4G-LTE network, digital TV transmission, access-point (AP) from wireless fidelity (WiFi), and so on. This paper will present and analyze all of these PCLs which include predictions of performance and ambiguity function (AF). Performance prediction is related to range detection which provides information about target detection range, radar cross section, and range-velocity resolution. While AF analyzes the transmit waveform of all PCL which gives a limit of resolution to the range and Doppler of adjacent targets. The results of the evaluation and analysis of performance predictions show that FM radio transmission (RRI) has a range and velocity resolution of 1 km and 12 m/s, respectively and the detection range at a maximum SNR of 15 dB is around 4 km. While the results of the AF evaluation on the PCL obtained range and Doppler resolution of around 2.73 km and 500 Hz, respectively.

Radar stations as a means of ensuring the security of critical information infrastructure

The paper systematizes the main characteristics of radar stations as a means of ensuring the security of critical information infrastructure. The main types of radar stations are analyzed. It is shown that the dominant type among radars are pulse radars of the centimeter and millimeter ranges, which use a single antenna, are quite simple and ergonomic when used for their intended purpose. The concepts of tactical and technical characteristics of radar stations are analyzed. The features of the main tactical characteristic - the range of the radar station are considered. It is shown that in order to determine the target detection range, taking into account the influence of environmental conditions and terrain (at the location of the radar station), it is necessary to use a system of equations containing the dependences of the detection ranges of energy, geometric, expected and actual (statistical). The correspondence of analytical calculations to actual results makes it possible to assess the reliability of assumptions about the reflecting properties of goals in various conditions of the situation while ensuring the security of critical information infrastructure.

Integrated Underwater Detection and Communication System Based on P4 Code-Modulated OFDM Signal

Because of the requirements of marine resources exploration and underwater cooperative operation, the underwater operation of common detection and communication equipment is difficult and unreliable. Therefore, it is urgent to establish an accurate underwater target detection and multi-node communication integrated system. An integrated method of underwater electric field detection and communication based on P4 code-modulated OFDM signal is proposed in response to the above requirements. The working principle, system structure, and signal processing of underwater electric field detection and electric field communication are similar. This article uses detection signal P4 code to modulate the phase of OFDM communication signal, thus realizing the integration of Underwater Detection and Communication System (IUDCS). The simulation results show that IUDCS can meet the detection range and velocity characteristics of underwater dynamic targets. The simulation results also meet the requirements for communication error rate and symbol error rate, thereby verifying the performance of underwater electric field IUDCS. This method is necessary for the realization of IUDCS in terms of reducing platform size, reducing power consumption, and enhancing concealment. Moreover, it shows good application prospects in underwater robot cluster operations.

TO ANALYZE THE TB-PCR POSITIVITY RATE USING REAL-TIME PCR FOR EARLY DETECTION OF TUBERCULOSIS

Objective: Tuberculosis is one of the leading causes of death worldwide. It is present in all the countries and among all age groups and also seen in both the genders. In investigating the early stage, identification, and rapid detection of tuberculosis, the PCR method (polymerase chain reaction) is one of the fast, safest, and reproducible new approaches. It covers all advantages such as the use of closed systems, reduced risk of carryover contamination, improved sensitivity and reproducibility, reduced turnaround time wide dynamic range of target detection, and feasibility for quantitation making it easy and reliable for the early detection of Mycobacterium tuberculosis. Methods: All samples used for the study are confirmed by conventional microscopic observation using acid-fast staining using ZN STAIN. The pulmonary sputum samples are obtained from clinical and radiological evidence of tuberculosis and these samples are selected for DNA extraction. Discussion: As per the statistical analysis using SPSS 22 version, it is found that the TB positivity rate (is 29.75%). Out of 119 positive patients (Male: 60.5% and Female: 39.5%). The average and standard deviation for CT values are 23.6 and 2.9, respectively. The 95% confidence interval of CT values for specimens is (22.7, 24.5). Average and standard deviation for CT values are equal in male patients and female patients. Age group-wise average and standard deviation for CT values are nearly equal. Results: The percentage of 3+ AFB positive grades having CT values between 20 and 24 is more than all other combinations of AFB positive grades and CT values. The average and standard deviation for CT values are 23.6 and 2.9, respectively. The 95% confidence interval of CT values for specimens is (22.7, 24.5). The average and standard deviation for CT values are equal in male patients and female patients. Conclusion: A significant improvement in specificity with high accuracy was achieved by a real-time PCR assay. Real-time PCR tests prove both a high degree of sensitivity in the upper respiratory sputum samples and for the early detection of the TB infection. The MTB real-time PCR test suitably identified the majority of the AFB positive and bacterial culture confirms TB.

Photon counting lidar working in daylight

Photon counting lidar has been widely used in long-distance target detection and long range active three-dimensional imaging fields due to its extremely high detecting sensitivity. The single-photon level sensitivity extends the detection range of the photon counting lidar, meanwhile makes it suffer from the noise interference. Especially, the strong sunlight background during the daytime limits the detection ability and applications of the photon counting lidar. In this paper, a new type of ultra-narrowband spectral filtering system is designed for the lidar, and based on which, a daytime working photon counting lidar system with 20 μJ pulse energy and 25 mm receiving aperture was established. A 24 km long-distance ranging experiment and a 22 km fast 3D imaging experiment were completed in daylight environment, which demonstrated outstanding daytime working performance of such a “small” lidar.

Концепция создания беспилотного самоходного аппарата для работы в угольных шахтах. Часть 2

The article is a continuation of the research described in the Russian Mining Industry Journal, Issue 5 (https://doi.org/10.30686/1609-9192-2022-5-00-00). This paper presents the Pathfinder Module of the unmanned self-propelled vehicle, which was developed within the framework of the Chameleon Project. Combination of this module with the Mule Basic Module makes it possible to create an unmanned a reconnaissance unmanned self-propelled vehicle. The Pathfinder Module is designed for terrain monitoring. This module is equipped with systems to create a mathematical model of the natural environment, which enables its movement if there is no communication with the operator. The module is equipped with a video-recording complex with the recording time of at least 4 hours, a binocular telescope with at least 18x zoom, a night vision device, a thermal imager with the angular resolution not exceeding 3° (the thermal target detection range of at least 1 000 m) and directional acoustic microphones. The article describes application scenarios of the Pathfinder Module, e.g. monitoring, reconnaissance, rescue and firefighting missions in a mine. The authors believe that serial production of the Chameleon range should begin as soon as possible as part of the import substitution program with the potential to export these products not only to the developing countries, but also to the countries with a high level of technological development.

Extended depth-of-field infrared imaging with deeply learned wavefront coding

Wavefront coding (WFC) techniques, including optical coding and digital image processing stages, enable significant capabilities for extending the depth of field of imaging systems. In this study, we demonstrated a deeply learned far-infrared WFC camera with an extended depth of field. We designed and optimized a high-order polynomial phase mask by a genetic algorithm, exhibiting a higher defocus consistency of the modulated transfer functions than works published previously. Additionally, we trained a generative adversarial network based on a synthesized WFC dataset for the digital processing part, which is more effective and robust than conventional decoding methods. Furthermore, we captured real-world infrared images using the WFC camera with far, middle, and near object distances. Their results after wavefront coding/decoding showed that the model of deeply learned networks improves the image quality and signal-to-noise ratio significantly and quickly. Therefore, we construct a novel artificial intelligent method of deeply learned WFC optical imaging by applying infrared wavelengths, but not limited to, and provide good potential for its practical application in "smart" imaging and large range target detection.

Low-Loss Heterogeneous Integrations With High Output Power Radar Applications at W-Band

This study presents a design of a 94-GHz high-performance and highly compact frequency-modulated continuous-wave radar sensor. In this sensor, an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula> -band CMOS-based all-digital phase-locked loop chip, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W$ </tex-math></inline-formula> -band SiGe-based transceiver monolithic microwave integrated circuit (MMIC), and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W$ </tex-math></inline-formula> -band GaN-based MMIC power amplifier (PA) are heterogeneously integrated (HI). Each part of the 130-nm bipolar complementary metal-oxide-semiconductor (BiCMOS) SiGe-based transceiver MMIC is designed to include a low-noise amplifier, PA, octupler, mixer, and lange coupler. The fabrication process of our in-house silicon-based MEMS photosensitive composite film is developed to provide very high-density integration and very low insertion loss of interconnections between chips. The HI front end of the radar sensor is measured on-wafer with a high output power of 22 dBm. Moreover, a low double-sideband noise figure (NF) of 10.2 dB is obtained. Bonding–substrate integrated waveguide (SIW)–WG transitions between the heterogeneously integrated front end and the antenna are specially designed and verified. A 2.3-dB degradation is observed, where 19.7 dBm is measured at the transmitter WG WR-10-flange. Thus, the sensor offers a 55-dB dynamic range at a 2-m position with an expectation of a long-distance target-detection range. The radar sensor has an 11.7-cm range resolution and is only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$60\times 40\times $ </tex-math></inline-formula> 8 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> in size, with a weight of only 78 g.

Development of a rangefinding method for determining the coordinates of targets by a network of radar stations in counter-battery warfare

The increase in the accuracy of determining the coordinates of targets is explained by the use of a network of counter-battery radar stations and the rangefinding method for determining the coordinates of targets. The main advantage of using the rangefinding method for determining the coordinates of targets in a network of counter-battery radar stations is to ensure the required accuracy in determining the coordinates of targets without using accurate measurement of angular coordinates. The minimum geometry of the system, which ensures the use of the rangefinding method for determining coordinates, is given. The method of determining the coordinates of targets by a network of counter-battery radar stations has been improved. In contrast to the known ones, information about the range to the target is additionally used in a spatially distributed network of radar stations for counter-battery combat. The boundaries of the working zones of the network of two and three counter-battery radar stations are calculated. The features of creating a continuous strip using the rangefinding method for determining the coordinates of the target are considered. Statistical modeling of the rangefinding method for determining the plane coordinates of the target has been carried out.&#x0D; It has been established that the use of the rangefinding method ensures the determination of the planar coordinates of the target in a sector of at least 120°. The targets are at a distance of direct radio visibility in relation to the counter-battery radar. The root-mean-square error in determining the target range in this case is no more than 50 m. It has been established that the creation of continuous bands of a low-altitude radar field at a certain height is possible by arranging radar stations in a line. In this case, the distance between the counter-battery radar stations should be no more than half the target detection range at this height

Periodic On–Off Keying Codes for Laser Radar Incoherent Pulse Compression

Pulsed laser systems for long range target detection process multiple pulses to increase signal-to-noise ratio SNR from that of a single pulse. Unipolar <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> – <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> keying (OOK) periodic pulse modulation codes are appropriate for an incoherent system. Mismatched filters for cross-correlation with codes are solutions to exactly determined linear equations, so all zero sidelobes are realized for any nonsingular set of equations and codes that are not all zeros. Therefore, maximum SNR is proposed as the criterion for code-filter pair adoption at a given code length. The fast solution of the mismatched filtering circulant equations allows all codes for a set of balancing values [differences of numbers of <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> (ones) and <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> (zeros)] to be tested for odd code lengths up through 33. M-sequences and Legendre codes of prime lengths one less than a multiple of four and an excess of one more <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> than <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> lead to optimal SNR code-filter pairs. These Legendre codes are suggested for longer codes since they are easily constructed. Code-filter pairs that optimize SNR for a given code length and balancing values of ±1, ±3, ±5, and ±7 are reported. For a balancing value of –1, a new set of codes with corresponding two-value filters is found.

РОЗРАХУНОК ЗОНИ УРАЖЕННЯ ЗЕНІТНОГО РАКЕТНОГО КОМПЛЕКСУ ЗА ДОПОМОГОЮ АЛГОРИТМУ БАГАТОКРИТЕРІАЛЬНОЇ ОПТИМІЗАЦІЇ

The kill zone is the main characteristic of the surface-to-air missile system, which characterizes, firstly, the combat capabilities of the system to hit targets of various types, and secondly, the energy capabilities of surface-to-air missiles to achieve targets, taking into account detailed calculation of the shape of the kill zone of the surface-to-air missile system is a time-consuming process, which without proper automation leads to unjustified time to perform. This article proposes a method of using a genetic algorithm with multicriteria optimization to automate the calculation of the kill zone of the surface-to-air missile system. The essence of the proposed technique is to find a set of pareto-optimal trajectories of a surface-to-air missile, the endpoints of which are the limit in terms of the ability to reach the aerial target with the necessary motion parameters and taking into account the range of target detection by fire-control radar of surface-to-air missile system. That is, one of the coordinates (the altitude or distance) of the boundary point can not be improved without the reducing of the other coordinate (the principle of pareto-optimality). This approach allows in the early stages of design to evaluate the kill zone of the surface-to-air missile system, being at design, and promptly implement effective technical solutions to increase its tactical and technical characteristics. Additional results of the calculation of the kill zone of the surface-to-air missile system according to the proposed method are data on the optimal launch angles of the surface-to-air missile, which can be taken into account when designing the launcher of the system, as well as data highlighting some features of surface-to-air missile flight.

Enhancing the Surveillance Detection Range of Image Sensors Using HDR Techniques

Image sensor-based surveillance systems are used for scene analysis, image sequence creation, and object detection. Natural scenes contain areas of high and low illumination, and standard cameras can only transform a fraction of the available visual information. The wide variation in illumination conditions limits the detection capabilities of image sensors. Therefore, in this study, the feasibility of applying high dynamic range (HDR) techniques using image sensors for enhancing range performance was investigated. The HDR requirements were analyzed, and available HDR techniques along with tone mapping and image enhancement were optimized for real-time scenarios. To determine the HDR requirements for specific visibility conditions, a theoretical analysis was conducted to evaluate camera performance using the human visual system. Additionally, a HDR imaging framework was established, and experiments were conducted to validate the performance of the framework. Results demonstrate that there is an empirical relationship between the dynamic range and visual detection range of the surveillance system. Subjective and objective evaluations indicate that surveillance cameras employing HDR imaging for long range applications have increased target detection range.

The Remote Control of the Artillery Rocket Set as a Strongly Nonlinear System Subject to Random Loads

On the modern battlefield, fighting capabilities, such as speed, target detection range, target identification capabilities, and shooting effectiveness, of short-range artillery rocket sets (ARSs) are constantly being improved. Problems arise when attempting to successfully fire such kits in the face of disruption from both the cannon and the moving platform on which the cannon is mounted. Furthermore, the set is a variable mass system since it can fire anywhere from a few to dozens or even hundreds of missiles in a brief period of time, implying that the ARS is a highly nonlinear system of variable parameters (non-stationary). This work shows how to control such a system. If the ARS is placed on a moving basis where there is both a system and measurement noise, the state variables must be restored, and the ARS data must be filtered. Therefore, in addition to the LQR regulator, an extended Kalman filter was used. As a consequence of this synthesis, an LQG (linear quadratic Gaussian) regulator of ARS was obtained, which was used to follow the target along the line of sight. The key goal of this paper is to develop control algorithms that will increase the performance of ARS control in elevation and azimuth, as well as the accuracy of achieving and eliminating maneuverable air targets. Moreover, through the quality criterion adopted, we hope to affect control energy costs while maintaining control precision. Graphical representations of certain computational simulation results are provided.

Multifunctional electrochemical biosensor with "tetrahedral tripods" assisted multiple tandem hairpins assembly for ultra-sensitive detection of target DNA.

Nucleic acids are genetic materials in the human body that play important roles in storing, copying, and transmitting genetic information. Abnormal nucleic acid sequences, base mutations, and genetic changes often lead to cancer and other diseases. Meanwhile, methylated DNA is one of the main epigenetic modifications, which is considered to be an excellent biomarker in the early detection, prognosis, and treatment of cancers. Therefore, a multifunctional electrochemical biosensor was constructed with sturdy tetrahedral tripods, which assisted multiple tandem hairpins through base complementary pairing and effective ultra-sensitive detection of targets (DNA, microRNA, and methylated DNA). In the experiments, experimental conditions were optimized, and different DNA concentrations in serum were detected to verify the sensitivity of the biosensor and the feasibility of this protocol. In addition, microRNA and DNA methylation were detected through different designs of tetrahedral tripods (TTs) that capture probes to prove the superiority of this scheme. A sturdy pyramid structure of TTs extremely enhanced the capture efficiency of targets. The targets triggered the one-step isothermal multi-tandem amplification reaction by incubating multiple hairpin assemblies. To our knowledge, a combination of two parts, which greatly reduced background interference and decreased non-specific substance interference, has appeared for the first time in this paper. Moreover, the load area of electrochemical substances was significantly increased than that in previous studies. This greatly increased the detection range and detection limit of targets. The electrochemical signal responses were generated in freely diffusing hexaammineruthenium(iii) chloride (RuHex). RuHex could adhere to the DNA phosphate backbone by a powerful electrostatic attraction, causing increased current responses.

Investigation of energy stealth of radar stations with band antennas from the radio monitoring complex

Using spectral representation of non-harmonic processes and partial characteristics of antennas, energy equations of transmissionreception of broadband signals in the radio channel with scattering on the object and the direct radio channel between the radar and the radio monitoring (RM) complex have been obtained. Energy of received signals is determined by value of product of spectral density of radiation power and partial moment of transmission-reception averaged in the range of cyclic frequencies. The signal-to-noise ratio at the receiver input reaches the highest value when the partial moment of transmission-reception of signals in the radio channel changes according to a linear law. At fixed average radar power, energy of information signals at incoherent accumulation can be increased due to selection of antennas with partial directive gain amplifying wave processes in areas of their spectra concentration. The range of the radar is proportional to the linear dimensions and significantly depends on the shape of the object. The rules of antenna characteristics selection are justified to ensure radar stealth from RM systems while maintaining the required range of target detection and recognition. When using an antenna with a partial directive gain constant in the range of working cyclic frequencies in the radar, and in the RM complex of an antenna system with a frequency-independent effective area, the partial moment of transmission-reception of signals in the forward radio channel is constant. Its value is determined by the product of partial directive gain at the central frequency of the range. Forms of pulses supplied to input of transmitting antenna and radiated into space coincide, and shape of signal at output of receiving antenna has the form of their derivative. Due to application of frequency-independent antennas in radar and RM complex, energy of probing signals increases compared to levels typical for antenna systems with partial directivity indices varying in proportion to current value of cyclic frequency in the first or second degree. This pattern is due to the significant effective area of the receiving antenna in the lower part of the frequency range, which parries the low efficiency of radiation of low-frequency components of the radar signal spectrum. In radio channels with partial moments of transmission-reception of signals varying with frequency increase according to linear law, energy supplied to receiver input increases in comparison with levels achievable at quadratic and cubic dependencies of partial moments on cyclic frequency due to the same type dependencies of partial directive gain antenna of radar and effective area of antenna of RM complex. Stealth of probing radiation increases as dimensions of radar antennas increase due to increase of partial directive gain and decreases as dimensions of antenna systems of RM complexes increase due to increase of their effective areas. The duty cycle of pulses forming regular sequences, established due to the condition of accumulation of energy of reflected signals due to irradiation of the object, which is required to complete the functional tasks of the radar, decreases in proportion to the increase of the partial directive gain antenna at the central cyclic frequency. Energy of information signals increases in proportion to coefficients depending on relative half-width of their spectra, and decreases with increase of central cyclic frequency to the second degree. As pulse repetition frequency increases at maximum permissible average density of radiation power limited by radar stealth requirements, energy density of probing signals decreases proportionally. The average power of the radar at a fixed level of spectral density varies in proportion to the bandwidth occupied by the probing signals due to a reduction in the following period.