Cumulative Detection Probability Research Articles

Occupancy patterns of the introduced, predatory sugar glider in Tasmanian forests

AbstractIntroduced mammals pose serious threats to native island fauna, and understanding their distribution is fundamental to evaluating their conservation impact. Introduced sugar gliders (Petaurus breviceps) are the main predator of critically endangered swift parrots (Lathamus discolor) on mainland Tasmania. We surveyed sugar glider occurrence over ~800 km2 in an important swift parrot breeding area, the Southern Forests. During 4–5 visits per site, we used call broadcast of predatory owls to elicit sugar glider alarm calls and surveyed 100 sites during February/March 2016. Naïve occupancy by sugar gliders was high (0.79), as was detectability (0.52 ± 0.03 SE), resulting in a cumulative detection probability of effectively 1. Occupancy modelling indicated a positive effect of the proportion of mature forest cover on occupancy. The best model, based on AIC scores, included the proportion of mature forest cover within a 500 m radius with constant detectability. Our study revealed surprisingly high rates of occupancy of available forest habitat throughout the heavily logged study area, such that even when mature forest cover was <10%, sugar glider occupancy was >0.5; where forest cover approached 100% (i.e. in the best quality breeding habitat for swift parrots), occupancy by sugar gliders approached 1. Our results reveal that sugar gliders are widespread across the study area which may be indicative of occupancy rates elsewhere in the breeding range of the critically endangered swift parrot. As a result, the risk of predation by sugar gliders for small birds may be widespread across logged Tasmanian forests. Additional work to identify whether population densities of sugar gliders vary with forest cover (and whether this may impact predation likelihood) is critical to understanding the conservation consequences of deforestation in the breeding range of the swift parrot.

탐색 레이다에서 누적확률에 기인한 탐지거리 계산에 관한 연구

The performance measure of airborne radars is the range at which the cumulative probability of detection has some specified value, because the per-scan detection probability is an oscillatory function of the target range in airborne radars operating with the dynamic clutter environment. As a result, no one range, at which the per-scan detection probability has a given value, can give a meaningful description of the range performance. In this paper, we provide the equation to calculate the cumulative detection probability and show that the result of Monte Carlo simulation is same as the calculated value in a simple scenario. This verified Monte Carlo model will be used to evaluate the performance of airborne radars in various operating scenarios, at which the numerical calculation is difficult.

Cumulative detection probabilities and range accuracy of a pulsed Geiger-mode avalanche photodiode laser ranging system

Cumulative pulses detection with appropriate cumulative pulses number and threshold has the ability to improve the detection performance of the pulsed laser ranging system with GM-APD. In this paper, based on Poisson statistics and multi-pulses cumulative process, the cumulative detection probabilities and their influence factors are investigated. With the normalized probability distribution of each time bin, the theoretical model of the range accuracy and precision is established, and the factors limiting the range accuracy and precision are discussed. The results show that the cumulative pulses detection can produce higher target detection probability and lower false alarm probability. However, for a heavy noise level and extremely weak echo intensity, the false alarm suppression performance of the cumulative pulses detection deteriorates quickly. The range accuracy and precision is another important parameter evaluating the detection performance, the echo intensity and pulse width are main influence factors on the range accuracy and precision, and higher range accuracy and precision is acquired with stronger echo intensity and narrower echo pulse width, for 5-ns echo pulse width, when the echo intensity is larger than 10, the range accuracy and precision lower than 7.5 cm can be achieved.

Species occupancy estimation and imperfect detection: shall surveys continue after the first detection?

Species occupancy, the proportion of sites occupied by a species, is a state variable of interest in ecology. One challenge in its estimation is that detection is often imperfect in wildlife surveys. As a consequence, occupancy models that explicitly describe the observation process are becoming widely used in the discipline. These models require data that are informative about species detectability. Such information is often obtained by conducting repeat surveys to sampling sites. One strategy is to survey each site a predefined number of times, regardless of whether the species is detected. Alternatively, one can stop surveying a site once the species is detected and reallocate the effort saved to surveying new sites. In this paper we evaluate the merits of these two general design strategies under a range of realistic conditions. We conclude that continuing surveys after detection is beneficial unless the cumulative probability of detection at occupied sites is close to one, and that the benefits are greater when the sample size is small. Since detectability and sample size tend to be small in ecological applications, our recommendation is to follow a strategy where at least some of the sites continue to be sampled after first detection.

Near-optimal probabilistic search using spatial Fourier sparse set

Autonomous search is an essential research topic for rescue and other robotic applications. However, searching for targets efficiently is still an unsolved problem. To achieve this objective, a robot needs to simultaneously maximize environmental coverage, maximize probability of detection (PD) and minimize motion cost. The problems associated with these objectives are NP-hard. This research reformulates the three objective functions as a maximum cumulative PD problem with motion cost. Since the PD function depends on the environment, the robot needs to both learn the PD function and the cost-to-go (CTG) function. This research proposes a reinforcement learning algorithm to learn the PD and CTG functions simultaneously. Since the PD function is sparse in the Fourier domain under certain subgoal patterns, spatial Fourier sparse set is proposed to learn PD functions based on the compressed sensing technique. The learned PD and CTG functions can then be used to generate subgoals that achieve $$(1-1/e)$$ of the optimum due to the submodularity. Experiments conducted with this algorithm demonstrate that the robot can search for the target faster than prior learning approaches (e.g., PMAC and FSS) and the benchmark model (e.g., PD).

Trajectory optimization under kinematical constraints for moving target search

Various recent events in the Mediterranean sea have shown the enormous importance of maritime search-and-rescue missions. By reducing the time to find floating victims, the number of casualties can be reduced. A major improvement can be achieved by employing unmanned aerial systems for autonomous search missions. In this context, the need for efficient search trajectory planning methods arises. Existing approaches either consider K-step-lookahead optimization without accounting for kinematics of fixed-wing platforms or propose a suboptimal myopic method. A few approaches consider both aspects, however only applicable to stationary target search. The contribution of this article consists of a novel method for Markovian target search-trajectory optimization. This is a unified method for fixed-wing and rotary-wing platforms, taking kinematical constraints into account. It can be classified as K-step-lookahead planning method, which allows for anticipation to the estimated future position and motion of the target. The method consists of a mixed integer linear program that optimizes the cumulative probability of detection. We show the applicability and effectiveness in computational experiments for three types of moving targets: diffusing, conditionally deterministic, and Markovian. This approach is the first K-step-lookahead method for Markovian target search under kinematical constraints.

Research on Phased Array Radar Resource Management in Searching Mode

Multifunction phased array radar, with rational management of time resource and energy resource, can search and track multiple targets simultaneously. A resource management optimization model for phased array radar in searching mode has been proposed, whose objection is to minimize the total resource consumption under the guarantee of searching performance with controllable parameters: search frame period, dwell time and signal duty circle. Both radial cumulative detection probability and tangential cumulative detection probability are considered in the searching performance. The consideration of tangential cumulative detection probability as one of the constraints is the main contribution here. The solution to this model by applying genetic algorithm suggests that this model is more suitable in actual scene.

A no-reference image quality measure based on CPBD and noise

In order to meet the needs of the objective evaluation of no-reference image, a no-reference image quality measure is presented. The measure is based on edge analysis and is suitable for images with noise. Taking properties of the Human Visual System(HVS) into account, we compute the probability of blur after getting the edge width and the local contrasts. And at last the image quality probability can be got considering cumulative probability of blur detection and the noise pollution degree. Experimental results show that the metric has a wide application, good anti-noise ability, simple calculation, as well as in high consistence with the subjective evaluation results.

Detection probabilities and sampling rates for Anisoptera exuviae along river banks: influences of bank vegetation type, prior precipitation, and exuviae size

Exuviae collections have considerable value in population studies of Odonata, but methods for standardizing collections or estimating densities and detection probabilities have been little studied. I measured sampling rates for Anisoptera exuviae and used a maximum likelihood, four-pass, depletion population estimator to standardize collections and to estimate exuvial densities and detection probabilities along 10 riverbank stations in Wisconsin. First-pass sampling rates averaged slower than the overall average for experienced collectors (0.53 m min–1 compared to 0.90 m min–1) because more exuviae were present on the first pass, increasing picking and handling time. Neither bank vegetation type (grassy versus forested) nor amount of prior precipitation affected sampling rate. Exuviae detection probabilities for a single pass ranged from 0.49 to 0.75, and averaged 0.64. The mean cumulative probability of detection increased to 0.87 after two passes, 0.95 after three passes, and 0.98 after four passes. A s...

Effect of time Pressure on Dynamic Visual Search Performance

A time limit usually exists in a real-life visual search task. This study investigated the effect of time pressure on dynamic visual search performance. A 2 (movement velocity: high vs. low) × 2 (time pressure: high vs. low) between-subject factorial design was used in this experiment. The time lengths corresponding to 63.2% cumulative probability of detection (i.e., time constant) and the probability of 50% were selected as low and high time pressure. When velocity was 4̊/s, 9.72 s and 6.89 s were chosen as the time limits for low and high time pressure respectively; when velocity was 16̊/s, 20.30 s and 14.22 s were chosen for low and high time pressure separately. There were 4 different experimental conditions: high velocity/high pressure, high velocity/low pressure, low velocity/high pressure, low velocity /low pressure, and no time-pressure control condition. 60 university students participated in this experiment. They were divided into 4 groups, i.e., each group included 15 students. Each participant took 20 search tasks in the experiment. The search time and accuracy of each participant were recorded. The difference in search performance between low time pressure condition and no time pressure condition was not significant whereas that between low time pressure condition and high time pressure condition was significant in the course of 4̊/s movement velocity. In the velocity of 16̊/s situation, the differences in performance between low time pressure and high time pressure conditions were not significant. Those results revealed that search performance was sensitive to time pressure under the situation of low movement velocity and the performance was not sensitive in the high velocity condition. The obtained results could be a reference for deciding the time limit (i.e., the permitted longest search time) for a specific visual search task.

Optimal multiplicative Bayesian search for a lost target

This paper deals with the problem of searching for not evading lost target by using Bayesian approach. The target may be stationary or drifting in one of n-disjoint bounded known regions. We use a team of n-searchers such that each region has a single searcher. The purpose here is to formulate a search model and obtains two candidate utility functions namely the mean time to detection and the cumulative probability of detection for the control solution. Furthermore, we maximize the chances of detecting the target given a restricted amount of time by maximizing probability of detection over the time horizon. The effectiveness of this method is illustrated by using a real world example with numerical results.

Multistatic performance prediction for Doppler-sensitive waveforms in a shallow-water environment

Navies worldwide are now operationally capable of exploiting multistatic sonar technology. One of the purported advantages of multistatics when detecting directional targets should be the increased probability of receiving a strong reflection at one of the multistatic receivers. However, it is not yet clear (or intuitive) how best to deploy multistatic-capable assets to achieve particular mission objectives. The Performance Assessment for Tactical Systems (PATS) software was recently developed by Maritime Way Scientific under contract to Defence Research and Development Canada as a research tool to assist in exploring different approaches to multistatic performance modelling. Beginning with a user-defined environment and sensor layout, PATS uses transmission loss and reverberation model results to calculate signal excess at each grid point in the model domain. Monte Carlo simulations using many realizations of target tracks allow for the calculation of the cumulative probability of detection as a means to assess performance. Results will be presented comparing the shallow-water performance of monostatic and multistatic sensors using frequency-modulated and Doppler-sensitive waveforms as well as omnidirectional and directional targets in a variety of realistic military scenarios.

Cumulative probability of prostate cancer detection using the international prostate symptom score in a prostate-specific antigen-based population screening program in Japan.

The International Prostate Symptom Score (IPSS) is often used as an interview sheet for assessing lower urinary tract symptoms (LUTS) at the time of prostate-specific antigen (PSA) testing during population-based screening for prostate cancer. However, the relationship between prostate cancer detection and LUTS status remains controversial. To elucidate this relationship, the cumulative probability of prostate cancer detection using IPSS in biopsy samples from patients categorized by serum PSA levels was investigated. The clinical characteristics of prostate cancer detected using IPSS during screening were also investigated. A total of 1,739 men aged 54-75 years with elevated serum PSA levels who completed the IPSS questionnaire during the initial population screening in Kanazawa City, Japan and underwent systematic transrectal ultrasonography-guided prostate biopsy between 2000 and 2013 were enrolled in the present study. Of the 1,739 men, 544 (31.3%) were diagnosed with prostate cancer during the observation period. The probability of cancer detection at 3 years in the entire study population was 27.4% and 32.7% for men with IPSS ≤ 7 and those with IPSS ≥ 8, respectively; there was no statistically significant difference between groups. In men with serum PSA levels of 6.1 to 12.0 ng/ mL at initial screening, the probability of cancer detection was significantly higher in men with IPSS ≤ 7 than in those with IPSS ≥ 8. There were no significant differences in clinical characteristics between groups of patients stratified by IPSS. These findings indicate that the use of IPSS for LUTS status evaluation may be useful for prostate cancer detection in the limited range of serum PSA levels.

Robust Spatial-Domain Based Super-Resolution Mosaicing of CubeSat Video Frames: Algorithm and Evaluation

In this paper, a spatial domain based super-resolution mosaicing system and its evaluation results are presented. This algorithm incorporates two main algorithms, an image mosaicing algorithm and a super-resolution-reconstruction algorithm. Huber-based prior information is used to address the ill-posed nature of the super resolution problem. To test the efficiency of the proposed algorithm, four performance metrics are used: mean square error, peak signal-to-noise ratio, singular value decomposition based measure, and cumulative probability of blur detection. Testing is performed using datasets generated from both a high altitude balloon and an Unmanned Aerial Vehicle (UAV). Results show that the proposed algorithm is highly efficient in real-time applications, such as remote sensing on a small satellite (i.e., CubeSat.) Furthermore, the performance metrics are proven to be accurate in quantitative evaluation.

대잠 헬기와의 협동 작전을 고려한 수상함의 최적 대잠탐색 패턴 산출을 위한 시뮬레이션

본 연구에서는 수상함과 대잠헬기가 협동작전을 수행하는 환경에서의 수상함의 최적 탐색 패턴을 도출하기 위한 시뮬레이션을 수행하였다. 이를 위해 대잠 탐색 작전을 수행하는 수상함과 대잠헬기의 기동 및 탐색 임무를 모델링하였으며, 탐색의 대상이 되는 잠수함의 회피 기동을 확률적 방법으로 모델링 하였다. 또한 수상함과 대잠 헬기가 수행하는 대잠 탐색 임무의 효과도를 정량적으로 측정하기 위한 지표들을 정의하였다. 대잠 탐색 작전의 주요 변수 중 하나인 수상함과 잠수함 예상위치간 초기 거리의 변화에 따른 시나리오들을 생성하였다. 각 시나리오에 대해, 수상함이 단독으로 최적 탐색 패턴에 따라 임무를 수행하는 경우와, 수상함과 대잠헬기가 협동 작전을 수행하는 경우에 대해 시뮬레이션을 수행하였다. 이를 통해 최근까지의 주요 연구 대상이 되어온 수상함들의 단독 작전을 가정한 최적 탐색 패턴으로는, 대잠헬기와의 협동 작전 환경에서 최대의 탐지 효과도를 얻을 수 없음을 밝히고, 협동 작전 환경에서 잠수함 탐지 확률을 최대화 하기위한 수상함의 기동 패턴 재구성 방안을 제안하였다. In this paper we analyzed the search patterns for the anti-submarine warfare (ASW) surface ships cooperating with ASW helicopters. For this purpose, we modeled evasive motion of a submarine with a probabilistic method. And maneuvers and search actions of ships and helicopters participating in the anti-submarine search mission are designed. And for each simulation scenario, the case where a ship and a helicopter searches a submarine independently according to its optimized search pattern is compared with the case where the search platforms participate in the ASW mission cooperatively. Based on the simulation results, we proposed the reconfigured search patterns that help cooperative ASW surface ships increase the total cumulative detection probability (CDP).

Duration of viraemia in Chinese acute sporadic hepatitis E

Acute sporadic hepatitis E (ASHE) cases induced by hepatitis E virus genotype 4 (HEV-4) are increasing in China. Our study aimed to estimate the duration of HEV-4 viraemia in Chinese ASHE. A total of 619 serum specimens from 499 ASHE patients were examined for the presence of HEV RNA. The association between viraemia detection and serum sampling time was compared between subtypes. The cumulative probability of HEV viraemia detection was determined using Kaplan-Meier survival analysis, and the viraemia duration was estimated. A total of 42.7 % of serum specimens were positive for HEV RNA and all the isolated strains were identified as genotype 4 and subsequently assigned to five subtypes. Among the patients infected with subtypes 4d and 4i, the time interval from the initiation of clinical symptoms to serum specimen sampling was shorter than that among the patients with subtypes 4a, 4b and 4h. Kaplan-Meier analysis was conducted with 101 sequential specimens as well as with both 101 sequential specimens and 236 single negative specimens. The cumulative probability of HEV-4 viraemia detection was estimated to decline quickly to approximately 10 % within 32 days after the initiation of clinical symptoms and then to decline very slowly to 5 % by the 41st day and to zero by the 131st day. The majority of ASHE cases maintain detectable HEV-4 viraemia within one month after onset, whereas a small portion of cases maintain long-term viraemia and may act as a reservoir for further transmission.

Cumulative probability of prostate cancer detection in biopsy according to free/total PSA ratio in men with total PSA levels of 2.1–10.0 ng/ml at population screening

The aim of this study was to investigate the cumulative probability of prostate cancer detection according to free/total prostate-specific antigen (PSA) ratio in men with PSA levels of 2.1-10.0ng/ml and also likelihood of detecting clinically insignificant prostate cancer in population-based screening. A total of 1,277 men aged between 55 and 69years with total PSA (tPSA) levels of 2.1-10.0ng/ml screened in population screening in Kanazawa city and underwent systematic transrectal ultrasonography-guided prostate biopsy between 2000 and 2011 were enrolled. The cumulative probability of prostate cancer detection in biopsy according to age, serum tPSA, and free-to-total PSA (f/t PSA) ratio was investigated. The clinicopathological features of screening-detected prostate cancer were also investigated. Of the 1,277 subjects in the study population, 320 (25.0%) were diagnosed with prostate cancer during the observation period. The probabilities of prostate cancer detection at 3years were 64.5, 41.2, 28.5, and 14.3% for the men with f/t PSA ratio ≤0.08, 0.09-0.13, 0.14-0.22, and ≥0.23, respectively; the differences in probabilities of prostate cancer detection among men with different f/t PSA ratios were statistically significant. Among 320 patients, 84 (26.3%) had favorable clinicopathological features that made them suitable for active surveillance. The f/t PSA ratio in unfavorable cancer patients was significantly lower that that in favorable cancer patients. The present study demonstrated that the f/t PSA ratio was a strong predictor of future cancer detection and unfavorable cancerous features in prostate biopsy in men with total PSA levels of 2.1-10.0ng/ml at population screening.

Estimation of the Infection Window for the 2010/2011 Korean Foot-and-Mouth Disease Outbreak

ObjectivesThis study aims to develop a method for calculating infection time lines for disease outbreaks on farms was developed using the 2010/2011 foot-and-mouth disease (FMD) epidemic in the Republic of Korea. MethodsData on farm demography, the detection date of FMD, the clinical history for the manifestation of lesions, the presence of antibodies against FMD virus (including antibodies against the structural and nonstructural proteins of serotype O), vaccination status (O1 Manisa strain), the number of reactors and information on the slaughter of infected animals were utilized in this method. ResultsBased on estimates of the most likely infection date, a cumulative detection probability that an infected farm would be identified on a specific day was determined. Peak infection was observed between late December and early January, but peak detection occurred in mid-January. The early detection probability was highest for pigs, followed by cattle (dairy, then beef) and small ruminants. Nearly 90% of the infected pig farms were detected by Day 11 post-infection while 13 days were required for detection for both dairy and beef cattle farms, and 21 days were necessary for small ruminant (goat and deer) farms. On average, 8.1 ± 3.1 days passed prior to detecting the presence of FMD virus on a farm. The interval between infection and detection of FMD was inversely associated with the intensity of farming. ConclusionThe results of our study emphasize the importance of intensive clinical inspection, which is the quickest method of detecting FMD infection and minimizing the damage caused by an epidemic.

Site occupancy models in the analysis of environmental DNA presence/absence surveys: a case study of an emerging amphibian pathogen

Summary The use of environmental DNA (eDNA) to detect species in aquatic environments such as ponds and streams is a powerful new technique with many benefits. However, species detection in eDNA‐based surveys is likely to be imperfect, which can lead to underestimation of the distribution of a species. Site occupancy models account for imperfect detection and can be used to estimate the proportion of sites where a species occurs from presence/absence survey data, making them ideal for the analysis of eDNA‐based surveys. Imperfect detection can result from failure to detect the species during field work (e.g. by water samples) or during laboratory analysis (e.g. by PCR). To demonstrate the utility of site occupancy models for eDNA surveys, we reanalysed a data set estimating the occurrence of the amphibian chytrid fungus Batrachochytrium dendrobatidis using eDNA. Our reanalysis showed that the previous estimation of species occurrence was low by 5–10%. Detection probability was best explained by an index of the number of hosts (frogs) in ponds. Per‐visit availability probability in water samples was estimated at 0·45 (95% CRI 0·32, 0·58) and per‐PCR detection probability at 0·85 (95% CRI 0·74, 0·94), and six water samples from a pond were necessary for a cumulative detection probability >95%. A simulation study showed that when using site occupancy analysis, researchers need many fewer samples to reliably estimate presence and absence of species than without use of site occupancy modelling. Our analyses demonstrate the benefits of site occupancy models as a simple and powerful tool to estimate detection and site occupancy (species prevalence) probabilities despite imperfect detection. As species detection from eDNA becomes more common, adoption of appropriate statistical methods, such as site occupancy models, will become crucial to ensure that reliable inferences are made from eDNA‐based surveys.

탐지효과도 및 누적탐지확률

탐지효과도 및 누적탐지확률