Passive Detection Research Articles

Scientific Findings of the Southern and Central Africa International Center of Excellence for Malaria Research: Ten Years of Malaria Control Impact Assessments in Hypo-, Meso-, and Holoendemic Transmission Zones in Zambia and Zimbabwe.

For a decade, the Southern and Central Africa International Center of Excellence for Malaria Research has operated with local partners across study sites in Zambia and Zimbabwe that range from hypo- to holoendemic and vary ecologically and entomologically. The burden of malaria and the impact of control measures were assessed in longitudinal cohorts, cross-sectional surveys, passive and reactive case detection, and other observational designs that incorporated multidisciplinary scientific approaches: classical epidemiology, geospatial science, serosurveillance, parasite and mosquito genetics, and vector bionomics. Findings to date have helped elaborate the patterns and possible causes of sustained low-to-moderate transmission in southern Zambia and eastern Zimbabwe and recalcitrant high transmission and fatality in northern Zambia. Cryptic and novel mosquito vectors, asymptomatic parasite reservoirs in older children, residual parasitemia and gametocytemia after treatment, indoor residual spraying timed dyssynchronously to vector abundance, and stockouts of essential malaria commodities, all in the context of intractable rural poverty, appear to explain the persistent malaria burden despite current interventions. Ongoing studies of high-resolution transmission chains, parasite population structures, long-term malaria periodicity, and molecular entomology are further helping to lay new avenues for malaria control in southern and central Africa and similar settings.

Geopolitical Implications of a Successful SETI Program

We discuss the recent “realpolitik” analysis of Wisian and Traphagan (2020) of the potential geopolitical fallout of the success of the Search for Extraterrestrial Intelligence (SETI). They conclude that “passive” SETI involves an underexplored yet significant risk. This is the risk that, in the event of a successful, passive detection of extraterrestrial technology, state-level actors could seek to gain an information monopoly on communications with an extraterrestrial intelligence. These attempts could lead to international conflict and potentially disastrous consequences. In response to this possibility, they argue that scientists and facilities engaged in SETI should preemptively engage in significant security protocols to forestall this risk. We find several flaws in their analysis. While we do not dispute that a realpolitik response is possible, we uncover concerns with Wisian and Traphagan's presentation of the realpolitik paradigm, and we argue that sufficient reason is not given to justify treating this potential scenario as action-guiding over other candidate geopolitical responses. Furthermore, even if one assumes that a realpolitik response is the most relevant geopolitical response, we show that it is highly unlikely that a nation could successfully monopolize communication with ETI. Instead, the real threat that the authors identify is based on the perception by state actors that an information monopoly is likely. However, as we show, this perception is based on an overly narrow contact scenario. Overall, we critique Wisian and Traphagan's argument and resulting recommendations on technical, political, and ethical grounds. Ultimately, we find that not only are Wisian and Traphagan's recommendations unlikely to work, they may also precipitate the very ills that they foresee. As an alternative to the Wisian and Traphagan recommendations, we recommend transparency and data sharing (which are consistent with currently accepted best practices), further development of postdetection protocols, and better education of policymakers in this space.

Fiber Bragg grating technology for biomedical ultrasound applications

Fiber Bragg gratings (FBGs) are a class of optical sensors that have been used widely in non destructive testing and monitoring. These sensors are compact, robust, inexpensive and immune to electromagnetic interference. FBGs serve as wavelength selective mirrors that reflect light at the Bragg wavelength. An applied strain results in a shift in the Bragg wavelength, which can be used to detect physical parameters such as temperature and pressure. Recent work suggests that FBGs could have potential for measurements in the biomedical ultrasound frequency range. In this presentation, I will provide an overview of ongoing work in our group on employing FBGs for applications in therapeutic ultrasound. Specifically, I will discuss calibration of these sensors along with their use in passive cavitation detection. I will also present recent results on detecting nonlinear waveforms relevant to focused ultrasound along with temperature measurement for thermal therapy. We envisage that these sensors will be useful in laboratory research environments, and for specialized therapy applications in the clinical setting.

Passive and active Doppler methods and metrics to quantify inertial cavitation induced by pulsed focused ultrasound

Inertial cavitation induced by pulses of nonlinearly distorted focused ultrasound (FUS) at moderate intensity can result in mild mechanical disruption of tissue, short of its complete mechanical disintegration—histotripsy. This effect can be used to enhance diffusion of subsequently systemically administered drugs or biologics. Previously, single-element passive cavitation detection (PCD) of broadband noise emissions was successfully used to quantify tissue disruption and enhancement in drug concentration. This metric, however, has limitations: minimal spatial resolution and challenges with calibration when used at large depths in acoustically variable tissue. To address this, we developed a combination of passive and active Doppler-based methods that relied on relative, rather than absolute signal metrics. Specifically, destructive cavitation behaviors were previously linked to substantial motion of the bubbles during the FUS pulse due to acoustic radiation force and shock scattering. This was reflected in the backscattered FUS harmonics as Doppler shift and measurable from PCD. The bubbles were observed to dissolve within milliseconds following each FUS pulse, thus their distribution could be visualized as an area of rapid change via fast plane wave Doppler ensemble following the FUS pulse. The Doppler power distribution was spatially correlated with the area of tissue disruption in the in vivo experiments. [Work supported by NIH R01CA154451, R01EB025187, and R01EB23910.]

Passive and Doppler-based assessment of cavitation activity induced by pulsed focused ultrasound

Pulsed focused ultrasound (pFUS) exposures utilizing short, nonlinearly distorted pulses at low duty cycle have been shown to enhance drug and gene delivery to targeted tissue through inertial cavitation activity. Passive cavitation detection (PCD) and mapping of broadband emissions are current conventional methods to monitor and quantify cavitation but provide limited spatial resolution. Here, plane-wave Doppler imaging was used with PCD to quantify pFUS-induced cavitation in ex vivo bovine tissues and in vivo surgically exposed porcine liver, kidney, and pancreas. A 1.5 MHz FUS transducer (aperture 75 mm, F-number 0.75) was used to deliver 60 pulses (duration 1 ms, 0.1% duty cycle, focal pressure p+ = 70i–110 MPa, p− = 13–20 MPa). A coaxially mounted ATL P7-4 ultrasound imaging probe was used for PCD during the FUS pulse, and Doppler and B-mode sequences. Disrupted tissue areas were collected for histology and compared to Doppler power images. Maximum Doppler power was found to correlate to broadband noise level for each FUS pulse. The Doppler power map integrated over the exposure was observed to correlate spatially with tissue disruption area from histology, which thus represents a promising real-time metric for quantifying cavitation activity induced by pFUS exposures. [Work supported by NIH R01CA154451, R01EB025187, and R01EB23910.]

Characterization and monitoring of cavitation behavior induced by a dual-mode pulsed high-intensity focused ultrasound array

Pulsed high-intensity focused ultrasound (pHIFU) is capable of inducing cavitation in tissue without the need for contrast agents, thereby enhancing permeability and passive drug penetration in tissue with poor perfusion. We have developed and characterized the performance of a 64-element linear ultrasound array for image-guided therapy, capable of generating sufficient levels of inertial cavitation at 1 MHz, along with B-mode and Doppler imaging for targeting and cavitation assessment, respectively. Cavitation behaviors induced by different pHIFU exposures were investigated using high-speed imaging in agarose and polyacrylamide phantoms in conjunction with passive cavitation detection (PCD) and plane wave Doppler imaging. Image quality assessment was performed on in vivo porcine models, and cavitation monitoring was demonstrated on ex vivo tissues. High-speed images of the induced cavitation behavior while steering the beam focus both axially and laterally (within ±1.2 cm) were in agreement with Doppler power distributions and broadband noise emissions from PCD. Destructive cavitation behaviors in both gels and tissue were induced at relatively low peak-negative pressures (3–4 MPa), provided that the pHIFU focal waveform was nonlinearly distorted. B-mode image quality is sufficient for recognizing the relative position of anatomic landmarks and targeting cm-sized regions. [Work supported by NIH grants R01EB023910 and R01EB025187.]

Blood–brain barrier opening in a large animal model using closed-loop microbubble cavitation-based feedback control of focused ultrasound sonication

Focused ultrasound (FUS) in combination with microbubbles has been established as a promising technique for noninvasive and localized Blood–brain barrier (BBB) opening. Real-time passive cavitation detection (PCD)-based feedback control of the FUS sonication is critical to ensure effective BBB opening without causing hemorrhage. This study evaluated the performance of a closed-loop feedback controller in a porcine model. Calibration of the baseline cavitation level was performed for each targeted brain location by a FUS sonication in the presence of intravenously injected microbubbles at a low acoustic pressure without inducing BBB opening. The target cavitation level (TCL) was defined for each target based on the baseline cavitation level. FUS treatment was then performed under real-time PCD-based feedback controller to maintain the cavitation level at the TCL. After FUS treatment, contrast-enhanced MRI and ex vivo histological staining were performed to evaluate the BBB permeability and safety. Safe and effective BBB opening was achieved with the BBB opening volume increased from 3.8 ± 0.7 to 53.6 ± 23.3 mm3 as the TCL was increased from 0.25 to 1 dB. This study validated that effective and safe FUS-induced BBB opening in a large animal model can be achieved with closed-loop feedback control of the FUS sonication.

Chain-to-Layer Dimensionality Engineering of Chiral Hybrid Perovskites to Realize Passive Highly Circular-Polarization-Sensitive Photodetection.

Chiral hybrid perovskites (CHPs), aggregating chirality and favorable semiconducting properties in one, have taken a prominent position in direct circularly polarized light detection (CPL). However, passive high circular polarization sensitivity (gres) photodetection in CHPs is still elusive and challenging. Benefitting from efficient control and turning of carrier transport of CHPs by dimensional engineering, here, we unprecedentedly proposed a chain-to-layer dimensionality engineering to realize high-gres passive photodetection. Two novel 2D layered CHPs (R/S-PPA)EAPbBr4 (2R/2S) (PPA = 1-phenylpropylamine, EA = ethylammonium) are successfully synthesized by alloying an EA cation with small steric hindrance into the chained CHPs (R/S-PPA)PbBr3 (1R/1S). Particularly, compared with the neglectable photoresponse in 1R, the obtained 2R by chain-to-layer dimensionality engineering gives rise to an excellent photoconductivity and robust polar photovoltage effect (PPE) with a giant open-circuit voltage of 2.5 V. Furthermore, such PPE promotes realizing an impressive gres in 2R up to 0.42 at zero bias because of the independent separation of photoexcited carriers, which is the highest value among the reported layered chiral perovskites. This work paves the way for the vigorous development of higher dimensional CHPs and will reveal their applications in the field of passive high-gres CPL detection.

A novel method for identifying coded tags recorded on aquatic acoustic monitoring systems

Aquatic biotelemetry increasingly relies on using acoustic transmitters (‘tags’) that enable passive detection of tagged animals using fixed or mobile receivers. Both tracking methods are resource-limited, restricting the spatial area in which movements of highly mobile animals can be measured using proprietary detection systems. Transmissions from tags are recorded by underwater noise monitoring systems designed for other purposes, such as cetacean monitoring devices, which have been widely deployed in the marine environment; however, no tools currently exist to decode these detections, and thus valuable additional information on animal movements may be missed. Here, we describe simple hybrid methods, with potentially wide application, for obtaining information from otherwise unused data sources. The methods were developed using data from moored, acoustic cetacean detectors (C-PODs) and towed passive receiver arrays, often deployed to monitor the vocalisations of cetaceans, but any similarly formatted data source could be used. The method was applied to decode tag detections that were found to have come from two highly mobile fish species, bass (Dicentrarchus labrax) and Twaite shad (Alosa fallax), that had been tagged in other studies. Decoding results were validated using test tags; range testing data were used to demonstrate the relative efficiency of these receiver methods in detecting tags. This approach broadens the range of equipment from which acoustic tag detections can be decoded. Novel detections derived from the method could add significant value to past and present tracking studies at little additional cost, by providing new insights into the movement of mobile animals at sea.

Passive sound detection of the helicopter in the far-field with a spectral coherence decomposition method

Helicopter detection is an important part of the safety and security during flight. Most of the aerodynamic noise of modern helicopters comes from the main rotor, the main rotor aerodynamic noise thus can be used for helicopter detection. However, the Signal-to-Noise Ratio (SNR) of the measurement noise has always been quite small while the helicopter is flying over long distance away from the microphone. The current passive detection methods are not robust enough in the presence of substantial interference. A robust passive sound detection method is proposed to detect the far-field helicopter based on the cyclostationarity of the main rotor noise. The Sparsity-Enhanced Spectral Coherence (SESC) is derived from the spectral coherence decomposition to improve the detection robustness at far distances and low SNR. Furthermore, a global detector is constructed to detect helicopters adaptively by fusing the detection of multiple orders of BPF, which can be performed on the calculated SESC. More accurate and robust detection of the far-field helicopter can be obtained by the proposed SESC detector. The effectiveness of the proposed detection approach is demonstrated and contrasted by using simulation and far-field flight test measurements of the ROBINSON R22 helicopter.

Remote Passive Sonar Detection by Relative Multiscale Change Entropy

Remote passive sonar detection is significant as it constitutes potential real-time monitoring of severe underwater threats. There is still a lack of an efficient approach to achieving weak ship signal detection with nonparametric and noninformation priors. We propose the relative multiscale change entropy (RMCE) method to tackle these problems that should be promising. It measures the similarity between the signal under test and the ambient noise by combining different time scale factors to perceive the small changes in the complexity of the ambient noise, which is led by the presence of the distant ship. The value of RMCE is demonstrated by simulation and applied to the actual recorded data. We analyze the distribution characteristics of relative multiscale entropy of the ambient noise data with and without ship noise, collected in the South China Sea. Then this article presents a Neyman–Pearson (N–P) criterion-based RMCE detector for ship signal detection in the marine environment. The results show that the RMCE method outperforms the narrowband energy detection (NBED) method considerably.

An innovative three-layer strategy in response to a quartan malaria outbreak among forest goers in Hainan Island, China: a retrospective study

BackgroundAn outbreak of Plasmodiummalariae infection among forest goers in Sanya City of Hainan Island, China was reported in 2015. In response to this outbreak, an innovative three-layer strategy (TLS) targeted forest goers was adapted based on the 1-3-7 approach.Main textKey elements of TLS are: (i) The village with five malaria cases and adjacent villages were set as the first layer. All residents including forest goers were taken as the high-risk population (HRP). Active case detection (ACD) by blood smear microscopy and PCR was selected as the primary measure, and passive case detection (PCD) as complementary measure. One case was identified under TLS implementation. (ii) The township with cases (Gaofeng Town) and the nearby towns were chosen as the second layer. Only forest goers were screened by ACD, while PCD as a routine screening method. 7831 blood smears collected by ACD and PCD and tested with negative results. (iii) The city with cases (Sanya City) and others 12 counties/county-level cities were selected as the third layer. Malaria cases were monitored passively. A total of 77,555 blood slides were screened by PCD with zero positive sample. For each layer, the malaria vector mosquitoes were monitored using light traps, cattle-baited/human-bait traps.Anophelesminimus (dominant species), An.sinensis and An.dirus were captured. Vector control measures mainly include insecticide residual spraying and long-lasting insecticide nets. The capacity of clinicians, public health practitioners and laboratory technicians has been improved through training. During 2016‒2018, TLS and chemoprophylaxis were implemented in the same areas. In the first layer, all residents were monitored by ACD, and malaria chemoprophylaxis were distributed, 89.5% of forest goers were using chemoprophylaxis against malaria. The blood smears (3126 by ACD plus 1516 by PCD) were with zero positive results. Chemoprophylaxis and ACD were offered to forest goers once a year, and PCD in residents as a complementary measure in the second and third layer, 77.8% and 95.1% of forest goers received chemoprophylaxis. In each layer, vector surveillance and control of malaria and trainings for medical staff were still in place.ConclusionsTLS was effective in blocking the outbreak by P.malariae among forest goers in Hainan in malaria elimination stage. However, whether it could prevent the malaria resurgence in the post-elimination phase needs to be further assessed.Graphical

Cavitation Characterization of Size-Isolated Microbubbles in a Vessel Phantom Using Focused Ultrasound.

Pharmaceutical delivery can be noninvasively targeted on-demand by microbubble (MB) assisted focused ultrasound (FUS). Passive cavitation detection (PCD) has become a useful method to obtain real-time feedback on MB activity due to a FUS pulse. Previous work has demonstrated the acoustic PCD response of MBs at a variety of acoustic parameters, but few have explored variations in microbubble parameters. The goal of this study was to determine the acoustic response of different MB size populations and concentrations. Four MB size distributions were prepared (2, 3, 5 µm diameter and polydisperse) and pulled through a 2% agar wall-less vessel phantom. FUS was applied by a 1.515 MHz geometrically focused transducer for 1 ms pulses at 1 Hz PRF and seven distinct mechanical indices (MI) ranging from 0.01 to 1.0 (0.0123 to 1.23 MPa PNP). We found that the onset of harmonic (HCD) and broadband cavitation dose (BCD) depends on the mechanical index, MB size and MB concentration. When matched for MI, the HCD and BCD rise, plateau, and decline as microbubble concentration is increased. Importantly, when microbubble size and concentration are combined into gas volume fraction, all four microbubble size distributions align to similar onset and peak; these results may help guide the planning and control of MB + FUS therapeutic procedures.

Adaptive Beamforming Approaches to Improve Passive Radar Performance in Sea and Wind Farms' Clutter.

This article presents the problem of passive radar vessel detection in a real coastal scenario in the presence of sea and wind farms’ clutter, which are characterised by high spatial and time variability due to the influence of weather conditions. Deterministic and adaptive beamforming techniques are proposed and evaluated using real data. Key points such as interference localisation and characterisation are tackled in the passive bistatic scenario with omnidirectional illuminators that critically increase the area of potential clutter sources to areas far from the surveillance area. Adaptive beamforming approaches provide significant Signal-to-Interference improvements and important radar coverage improvements. In the presented case study, an aerial target is detected 28 km far from the passive radar receiver, fulfilling highly demanding performance requirements.

Evaluation of a haemozoin-based rapid diagnostic test for diagnosis of imported malaria during the phase of prevention of reestablishment in Sri Lanka

BackgroundSri Lanka, an island nation, has eliminated endemic malaria transmission. Maintaining elimination in the continued presence of vectors requires vigilance in screening people travelling from high malaria-risk areas and a rapid response with focal screening for infections identified in the community. Such screening requires accurate and very rapid assays that enable an immediate response. Both microscopy and rapid diagnostic tests (RDTs) have limitations including sensitivity and speed in screening large numbers, while polymerase chain reaction (PCR) is practical only as laboratory confirmation. This study assessed the utility of ‘Gazelle’, a novel rapid malaria assay based on magneto-optical detection of haemozoin, a by-product of malaria parasite metabolism.MethodsBetween October 2020 and March 2021, two groups of individuals were screened for malaria by four methods, namely, microscopy, Rapid Diagnostic Test (RDT), Gazelle and PCR. Passive case detection was carried out for confirmation of diagnosis amongst individuals suspected of having malaria. Individuals at high-risk of acquiring malaria, namely persons returning from malaria endemic countries, were screened by active case detection.ResultsOf the 440 individuals screened for malaria, nine malaria positives were diagnosed by PCR, microscopy and the HRP2 band of RDT, which included five Plasmodium falciparum infections, two Plasmodium ovale, and one each of Plasmodium vivax and Plasmodium malariae. Gazelle correctly detected the P. vivax, P. ovale and P. malariae infections within the 2 min test time, but did not detect two P. falciparum infections giving a sensitivity of 77.8%. Specificity was 100%.DiscussionThe Gazelle, a portable bench top device proved useful to screen a large number of blood samples for non-falciparum parasites within 5 minutes of sample input. Species differentiation, and improvement in P. falciparum detection, will be important to broaden utility.

MRisk: Continuous Risk Estimation for Smoking Lapse from Noisy Sensor Data with Incomplete and Positive-Only Labels.

Passive detection of risk factors (that may influence unhealthy or adverse behaviors) via wearable and mobile sensors has created new opportunities to improve the effectiveness of behavioral interventions. A key goal is to find opportune moments for intervention by passively detecting rising risk of an imminent adverse behavior. But, it has been difficult due to substantial noise in the data collected by sensors in the natural environment and a lack of reliable label assignment of low- and high-risk states to the continuous stream of sensor data. In this paper, we propose an event-based encoding of sensor data to reduce the effect of noises and then present an approach to efficiently model the historical influence of recent and past sensor-derived contexts on the likelihood of an adverse behavior. Next, to circumvent the lack of any confirmed negative labels (i.e., time periods with no high-risk moment), and only a few positive labels (i.e., detected adverse behavior), we propose a new loss function. We use 1,012 days of sensor and self-report data collected from 92 participants in a smoking cessation field study to train deep learning models to produce a continuous risk estimate for the likelihood of an impending smoking lapse. The risk dynamics produced by the model show that risk peaks an average of 44 minutes before a lapse. Simulations on field study data show that using our model can create intervention opportunities for 85% of lapses with 5.5 interventions per day.

Machine learning guided electrochemical sensor for passive sweat cortisol detection

A noninvasive sensor was developed on a flexible, nano-porous substrate with the capability to detect cortisol passively from human sweat. A Machine Learning (ML) algorithm was also developed to analyze sensor data to detect rising and falling trends of cortisol with time, which can potentially inform the wearer of rising or falling cortisol levels. Sensor response was measured by Electrochemical Impedance Spectroscopy (EIS) assay with spiked synthetic sweat within the physiological concentration range of cortisol, for which responses to low, medium, and high concentrations were significant. Calibration studies established a dynamic range of 8–140 ng/ml and EIS demonstrated a dose-dependent response and operational frequency range of 100–500 Hz. Inter-assay and intra-assay variations were below 20%. One-way ANOVA and post hoc Tukey test established significant response (p < 0.05) to different concentrations of cortisol. EIS was performed with dosing ranging from high-low and low-high concentrations of cortisol, to simulate rising and falling cortisol levels over time. Rate of change of response to shifts in cortisol concentration was used to train a weighted K nearest neighbor (KNN) machine learning algorithm to detect and classify increasing and decreasing cortisol in sweat. Accuracy was validated to be 100% by k means cross validation. Sensor analysis of sweat samples from human subjects showed a 100% accuracy in testing with the algorithm along with a 100% True positive and 0% False negative rate, thus showing that a wearable sweat sensor can be used with ML to detect rising and falling trends in cortisol for on demand, noninvasive sensing.

Investigation of Inertial Cavitation Induced by Modulated Focused Ultrasound Stimuli

Abstract A passive cavitation detection setup is used to assess and verify the capability of frequency- and amplitudemodulated ultrasound burst signals on the generation of inertial cavitation. The measurements were conducted with a flowthrough tissue-mimicking phantom with a canal of dc = 1mm in diameter simulating a fine blood vessel. By means of a flow velocity of vf= 50mm/s circulating blood in the cardiovascular system is imitated. Applying signal frequencies from f = 550 − 950 kHz and peak rarefaction pressures in a range from ˆpPRFP ≈ 0.17 − 1.81 MPa, various ultrasound stimuli with alternating signal parameters were investigated in the absence and presence of a talcum-water mixture acting as cavitation nuclei. By evaluating the broadband emissions in the frequency domain and calculating the voltage spectral density Srm, the results can be compared. The findings of the present study demonstrate that each ultrasound stimulus triggers a similar strength of cavitation noise at the same Mechanical Index, representing a certain pressure. Over the whole frequency and Mechanical Index (pressure) range, each ultrasound signal type generates a voltage spectral density from Srm= 0.25 − 2.25 V/ √ Hz.

A Self-Powered P-SSHI Array Interface for Piezoelectric Energy Harvesters With Arbitrary Phase Difference

Piezoelectric energy harvester (PEH) arrays are promising in many application scenarios. However, few interface circuits have been developed to manage the multiple ac inputs from PEHs. This article proposes an extensible parallel synchronized switch harvesting on inductor array interface scheme to realize a multiinput conversion from PEH arrays. We develop a split-inductor-capacitor topology that can extract electrical energy from multiple PEHs. The proposed circuit topology effectively handles the inductor access conflict in the cases of PEHs with close, identical, and opposite vibration phases, insensitive to ac input phase changes. For demonstrating the capability of dealing with multiple ac inputs from PEHs and the enhancement effect on power output, we construct and test a self-powered three-channel array circuit with the passive peak detection function. Excited by sinusoidal vibrations, our circuit effectively avoids the energy return and efficiently achieves the power combination of the three PEHs. Compared with the classic full-bridge circuit, the proposed circuit helps increase the power output by 4.8 times. Also, to show the universality of the circuit, the circuit's operation under various excitations istested and analyzed.

PAPR Reduction of OFDM Waveform in Integrated Passive Radar and Communication Systems

For the dual-function radar and communication (DFRC) system based on the orthogonal frequency division multiplexing (OFDM) signal, low peak-to-average power ratio (PAPR) design of the waveform is very important to improve the transmitting efficiency and overall performance. In this paper we consider this problem in the context of the integrated passive radar and communication (IPRC) system in which the channel state information (CSI) and transmitting waveform are unknown to the passive radar. In this context, the traditional constellation extension method is applicable but the effect of PAPR reduction is limited by the constellation size. To solve this problem, we propose a low PAPR waveform design method suitable for a large constellation size. The new method makes two improvements to significantly reduce the PAPR by increasing the constellation point participating in the extension and expanding the extension regions, which is independent of the CSI. Specifically, we adjust the extension regions by the scaling factor to obtain different PAPR, while remaining the pilot data unchanged. Furthermore, the communication performance is semi-analytically analyzed, and the consistency of semi-analytical results and simulation results verifies the effectiveness of the proposed method. Analysis and numerical results demonstrate that the proposed method can achieve good comprehensive performance of communication and passive radar detection compared with other methods in the case of large constellation size.