Temporal Degradation Research Articles

Learning Adaptive Discriminative Correlation Filters via Temporal Consistency Preserving Spatial Feature Selection for Robust Visual Object Tracking

With efficient appearance learning models, discriminative correlation filter (DCF) has been proven to be very successful in recent video object tracking benchmarks and competitions. However, the existing DCF paradigm suffers from two major issues, i.e., spatial boundary effect and temporal filter degradation. To mitigate these challenges, we propose a new DCF-based tracking method. The key innovations of the proposed method include adaptive spatial feature selection and temporal consistent constraints, with which the new tracker enables joint spatial-temporal filter learning in a lower dimensional discriminative manifold. More specifically, we apply structured spatial sparsity constraints to multi-channel filters. Consequently, the process of learning spatial filters can be approximated by the lasso regularization. To encourage temporal consistency, the filter model is restricted to lie around its historical value and updated locally to preserve the global structure in the manifold. Last, a unified optimization framework is proposed to jointly select temporal consistency preserving spatial features and learn discriminative filters with the augmented Lagrangian method. Qualitative and quantitative evaluations have been conducted on a number of well-known benchmarking datasets such as OTB2013, OTB50, OTB100, Temple-Colour, UAV123, and VOT2018. The experimental results demonstrate the superiority of the proposed method over the state-of-the-art approaches.

Recovery of information from latent memory stores decreases over time

ABSTRACTWorking memory (WM) performance can be enhanced by an informative cue presented during storage. This effect, termed a retrocue benefit, can be used to explore how observers prioritize information stored in WM. Recent studies have demonstrated that neural representations of task-relevant memoranda are strengthened following a retrocue, suggesting that participants can supplement active memory traces with information from other memory stores. We sought to better understand these additional store(s) by asking whether they are subject to the same temporal degradation seen in active memory representations during storage. We tested this possibility by reconstructing and quantifying representations of remembered positions from EEG activity while varying the interval separating an encoding display and retrocue during a spatial WM task. We observed a significant increase in the quality of location-specific representations following a retrocue, but the magnitude of this benefit was linearly and inversely related to the timing of the retrocue such that later cues yielded smaller increases. This result suggests that participants’ ability to supplement active memory representations with information from additional memory stores is not static: the information maintained in these stores may be subject to temporal degradation, or these stores may become more difficult to access over time.

Bone resorption and body reorganization during maturation induce maternal transfer of toxic metals in anguillid eels.

During their once-in-a-lifetime transoceanic spawning migration, anguillid eels do not feed, instead rely on energy stores to fuel the demands of locomotion and reproduction while they reorganize their bodies by depleting body reserves and building up gonadal tissue. Here we show how the European eel (Anguilla anguilla) breaks down its skeleton to redistribute phosphorus and calcium from hard to soft tissues during its sexual development. Using multiple analytical and imaging techniques, we characterize the spatial and temporal degradation of the skeletal framework from initial to final gonadal maturation and use elemental mass ratios in bone, muscle, liver, and gonadal tissue to determine the fluxes and fates of selected minerals and metals in the eels' bodies. We find that bone loss is more pronounced in females than in males and eventually may reach a point at which the mechanical stability of the skeleton is challenged. P and Ca are released and translocated from skeletal tissues to muscle and gonads, leaving both elements in constant proportion in remaining bone structures. The depletion of internal stores from hard and soft tissues during maturation-induced body reorganization is accompanied by the recirculation, translocation, and maternal transfer of potentially toxic metals from bone and muscle to the ovaries in gravid females, which may have direct deleterious effects on health and hinder the reproductive success of individuals of this critically endangered species.

Differential effects of sound level and temporal structure of calls on phonotaxis by female gray treefrogs, Hyla versicolor.

We investigated how communication distance influenced the efficacy of communication by studying the effects of two attributes of male chorus sounds, namely, reduction in sound level and degradation of temporal sound structure, on attraction and accuracy of female phonotaxis in gray treefrogs, Hyla versicolor. For this, we conducted acoustic playback experiments, using synthetic calls and natural calls recorded at increasing distances from a focal male as stimuli. We found that the degradation of temporal structure had a greater effect on signal attractiveness than did the reduction in sound level, and that increasing sound level preferentially affected the attractiveness of proximally recorded calls, with less temporal degradation. Unlike signal attraction, accuracy of female localization increased systematically with the sound level. These results suggest that the degradation of temporal fine structure from both the chorus and signal-environmental effects imposes a limit for effective communication distances for female treefrogs in nature.

Enhancement of temporal regularity and degradation of spatial synchronization induced by cross-correlated sine-Wiener noises in regular and small-world neuronal networks

Most previous studies assumed noise to be unbounded Gaussian. Here the effects of non-Gaussian cross-correlated sine-Wiener (CCSW) bounded noises on temporal regularity and spatial synchronization of coupled neurons are investigated in regular and small-world networks of the FitzHugh–Nagumo (FHN) neurons. For regular neuronal networks, as cross-correlation time of CCSW noises is increased, CCSW noises-induced temporal coherent resonance occurs at appropriately cross-correlation time of CCSW noises, and spatial synchronization in neuronal network is always impaired. In addition, the increasing degree of correlation of CCSW noises may enhance or impair temporal regularity, which is dependent on cross-correlation time. On the other hand, the increasing degree of correlation of CCSW noises destroys spatial synchronization or has no effect on spatial synchronization. For small world neuronal network, CCSW noises-induced enhancement of temporal regularity and degradation of spatial synchronization are still observed. Furthermore, the increasing rewiring probability make spatiotemporal pattern more order in time and in space. If delay is introduced into small world network, the aforementioned CCSW noises-induced phenomena still exist. Meanwhile, delay let spatiotemporal pattern more disorder.

Simulation of grating compressor misalignment tolerances and mitigation strategies for chirped-pulse-amplification systems of varying bandwidths and beam sizes.

The effects of pulse compressor grating misalignment on pulse duration and focusability are simulated for chirped-pulse-amplification systems of varying bandwidths, beam sizes, groove densities, and incident angles. Tilt-alignment tolerances are specified based on a 2 drop in focused intensity, illustrating how tolerances scale with bandwidth and compressor beam size, which scales with energy when transformed via known grating damage thresholds. Grating-alignment tolerance scaling with grating groove density and incident/diffracted angles is investigated and applied to compressor design. A correlation between grating tip and in-plane rotation error sensitivity is defined and used to compensate residual out-of-plane angular dispersion, even for ultra-broadband pulses. Simulation of dispersion compensation methods after grating misalignment is shown to mitigate pulse lengthening, limited by temporal contrast degradation and higher-order effects for ultrabroad bandwidths.

Multi-scale graph modeling and analysis of locomotion dynamics towards sensor-based dementia assessment

Dementia is a general neurodegenerative disorder beyond normal aging, which is not only overwhelming for the patients, but also negatively affects their caregivers and families. In the state of the art, paper-based survey methods such as the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) are widely used for the assessment of dementia conditions. However, these methods require lab visits or administration from nurses, physicians and examiners, and are limited in the ability to track temporal degradation (or daily variations) of dementia conditions. With rapid advances in sensing technology, there is growing interest in the development of new, sensor-based methods that provide more flexibility in dementia monitoring and require minimal interventions from practitioners. In this article, we propose a new, sensor-based method that estimates dementia conditions with daily locomotion data. The proposed methodology is evaluated and validated with both simulation and real-world case studies. Experimental results show the compelling predictive accuracy, with both true positive and true negative rates above 85%. This article shows that sensor-based methods have great potential for real-time monitoring of temporal variations of dementia conditions from daily gait locomotion dynamics.

Superresolution stacking based on sparse Radon transform

Normal moveout (NMO) correction is routinely applied to each common-midpoint (CMP) gather before forming a stack section. Trace stretching is inherent in the conventional NMO correction, causing frequency distortion and temporal resolution degradation in the stacked image. We have developed a novel method to compute a superresolution stack directly from CMP gathers by solving an optimization problem that leads to an [Formula: see text]-norm minimization of the model based on compressive sensing principles. Our algorithm is able to recover the superposition of signals in a specialized parallel-shifted hyperbolic Radon-transform domain. The superresolution stacking result is then extracted directly from the transform domain without inversely transforming back to the time-offset domain. The effectiveness of the developed methodology in producing superresolution stack images was tested on a synthetic data set and a land data set from central Saudi Arabia. Test results clearly indicate that our method reduces the stretch effect, enhances the signal, attenuates multiples and noise, and results in a substantial improvement on the temporal and spatial resolutions of the stack image especially in regions dominated by noise.

SUBHDIP: process variations tolerant subthreshold Darlington pair‐based NBTI sensor circuit

Aggressive technology scaling has inevitably led to reliability becomes a major concern for modern high-speed and high-performance integrated circuits. The major reliability concerns in nanoscale very-large-scale integration design are the time-dependent negative bias temperature instability (NBTI) degradation. Owing to increasing vertical oxide field and higher operating temperature, the threshold voltage of P-channel MOS transistors increases with time under NBTI. This study presents a novel subthreshold Darlington pair-based NBTI degradation sensor under the stress conditions. The proposed sensor provides the high degree of linearity and sensitivity under subthreshold conditions. The Darlington pair used in the circuit provides the stability and the high-input impedance of the circuit makes it less affected by the process variations. Owing to high sensitivity, the proposed sensor is best suited for sensing of temperature variation, process variation, and temporal degradation during measurement. The sensitivity of the proposed sensor at room temperature is 0.239 mV/nA under subthreshold conditions. The proposed sensor is less affected by the process variation and has the maximum deviation of 0.0011 mV at standby leakage current of 30 nA.

On-Orbit Relative Radiometric Calibration of the Night-Time Sensor of the LuoJia1-01 Satellite.

The LuoJia1-01 satellite can acquire high-resolution, high-sensitivity nighttime light data for night remote sensing applications. LuoJia1-01 is equipped with a 4-megapixel CMOS sensor composed of 2048 × 2048 unique detectors that record weak nighttime light on Earth. Owing to minute variations in manufacturing and temporal degradation, each detector’s behavior varies when exposed to uniform radiance, resulting in noticeable detector-level errors in the acquired imagery. Radiometric calibration helps to eliminate these detector-level errors. For the nighttime sensor of LuoJia1-01, it is difficult to directly use the nighttime light data to calibrate the detector-level errors, because at night there is no large-area uniform light source. This paper reports an on-orbit radiometric calibration method that uses daytime data to estimate the relative calibration coefficients for each detector in the LuoJia1-01 nighttime sensor, and uses the calibrated data to correct nighttime data. The image sensor has a high dynamic range (HDR) mode, which is optimized for day/night imaging applications. An HDR image can be constructed using low- and high-gain HDR images captured in HDR mode. Hence, a day-to-night radiometric reference transfer model, which uses daytime uniform calibration to calibrate the detector non-uniformity of the nighttime sensor, is herein built for LuoJia1-01. Owing to the lack of calibration equipment on-board LuoJia1-01, the dark current of the nighttime sensor is calibrated by collecting no-light desert images at new moon. The results show that in HDR mode (1) the root mean square of mean for each detector in low-gain (high-gain) images is better than 0.04 (0.07) in digital number (DN) after dark current correction; (2) the DN relationship between low- and high-gain images conforms to the quadratic polynomial mode; (3) streaking metrics are better than 0.2% after relative calibration; and (4) the nighttime sensor has the same relative correction parameters at different exposure times for the same gain parameters.

Field Propagation Experiments of Male African Savanna Elephant Rumbles: A Focus on the Transmission of Formant Frequencies.

Simple SummaryAfrican savanna elephants are highly social and exhibit a complex vocal communication system. They use a low-frequency contact call (termed ‘rumble’) to maintain social contact over long distances. As sound travels through the environment, however, its intensity level decreases. We used specialized computer software to manipulate acoustic components in male rumbles and simulated different body sizes (large and small). The rumbles were broadcasted and re-recorded at different distances at the Addo Elephant National Park, South Africa. This propagation experiment enabled us to investigate which acoustic components and information content can be transmitted efficiently up to 1.5 km. The results confirm that male rumbles potentially encode information about body size, yet transmission success decreased with distance. Our findings inform on how the environment can influence propagation of savanna elephant rumbles and what kind of information might be transmitted successfully over distance.African savanna elephants live in dynamic fission–fusion societies and exhibit a sophisticated vocal communication system. Their most frequent call-type is the ‘rumble’, with a fundamental frequency (which refers to the lowest vocal fold vibration rate when producing a vocalization) near or in the infrasonic range. Rumbles are used in a wide variety of behavioral contexts, for short- and long-distance communication, and convey contextual and physical information. For example, maturity (age and size) is encoded in male rumbles by formant frequencies (the resonance frequencies of the vocal tract), having the most informative power. As sound propagates, however, its spectral and temporal structures degrade progressively. Our study used manipulated and resynthesized male social rumbles to simulate large and small individuals (based on different formant values) to quantify whether this phenotypic information efficiently transmits over long distances. To examine transmission efficiency and the potential influences of ecological factors, we broadcasted and re-recorded rumbles at distances of up to 1.5 km in two different habitats at the Addo Elephant National Park, South Africa. Our results show that rumbles were affected by spectral–temporal degradation over distance. Interestingly and unlike previous findings, the transmission of formants was better than that of the fundamental frequency. Our findings demonstrate the importance of formant frequencies for the efficiency of rumble propagation and the transmission of information content in a savanna elephant’s natural habitat.

Alternating Magnetic Force Microscopy: Effect of Si doping on the temporal performance degradation of amorphous FeCoB magnetic tips

In order to increase the resolution of traditional MFM and extend its applications in the past, we created an Alternating Magnetic Force Microscopy (A-MFM) with a magnetic force modulation by applying an off-resonance AC magnetic field. A new magnetic tip has been developed for A-MFM in this work. Perpendicular magnetic recording medium with 500 kfci recording density is successfully imaged and analyzed by using the new tips coated by 6–15 nm amorphous FeCoSiB-based soft magnetic film. The effect of Si doping to the magnetic film on the A-MFM imaging was studied. It was found that Si additive had no effect on the imaging properties, such as signal-to-noise ratio and spatial resolution (kept at ∼5 nm level). But on other side, Si additive significantly degraded the chemical stability of FeCoSiB film due to oxidation in ambient atmosphere. Surface passivation by metal and boron oxides is considered to have a main effect on improvement of chemical stability of Si-free magnetic coating. The results have shown that Si-free FeCoB-based magnetic tips are appropriate candidates for A-MFM imaging in ambient conditions.

Fixed Pattern Noise and Temporal Noise Degradation Induced by Radiation Effects in Pinned Photodiode CMOS Image Sensors

The experiments of the pinned photodiode complementary metal–oxide–semiconductor (CMOS) image sensors irradiated by 60Co $\gamma $ rays, neutrons, and protons are presented. The CMOS image sensors are manufactured using a standard 0.18- $\mu \text{m}$ CMOS technology with 4 MP. The fixed pattern noise (FPN) and temporal noise versus the total doses at different dose rates are analyzed. The FPN and temporal noise degradations induced by 60Co $\gamma $ rays with different biased conditions are compared. The FPN and temporal noise degradations induced by displacement damage are also investigated by proton and neutron radiation. The degradation mechanisms of the FPN and temporal noise induced by 60Co $\gamma $ ray, neutron, and proton radiation are analyzed.

The acoustic adaptation hypothesis in a widely distributed South American frog: Southernmost signals propagate better

Animal communication occurs in environments that affect the properties of signals as they propagate from senders to receivers. We studied the geographic variation of the advertisement calls of male Pleurodema thaul individuals from eight localities in Chile. Furthermore, by means of signal propagation experiments, we tested the hypothesis that local calls are better transmitted and less degraded than foreign calls (i.e. acoustic adaptation hypothesis). Overall, the advertisement calls varied greatly along the distribution of P. thaul in Chile, and it was possible to discriminate localities grouped into northern, central and southern stocks. Propagation distance affected signal amplitude and spectral degradation in all localities, but temporal degradation was only affected by propagation distance in one out of seven localities. Call origin affected signal amplitude in five out of seven localities and affected spectral and temporal degradation in six out of seven localities. In addition, in northern localities, local calls degraded more than foreign calls, and in southern localities the opposite was observed. The lack of a strict optimal relationship between signal characteristics and environment indicates partial concordance with the acoustic adaptation hypothesis. Inter-population differences in selectivity for call patterns may compensate for such environmental constraints on acoustic communication.

Distribution, source, and risk of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in urban and rural soils around the Yellow and Bohai Seas, China

Between 1945 and 1983, China was the world's largest producer of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), and the second largest producer of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs). The provinces of Liaoning, Hebei, Tianjin, Shandong, and Jiangsu around the Yellow and Bohai Seas have a long history of production and usage of OCPs and PCBs. To investigate their residual concentration, distribution, risk level, and temporal degradation, 7 OCPs and 7 indicator PCBs were determined in surface soils collected around the Yellow and Bohai Seas. Residues of the 7 OCPs and 7 PCBs were in the range of 5.89–179.96 ng g−1 dry weight (dw) and non-detectable (ND)–385.67 ng g−1 dw, respectively. Tianjin and Hebei provinces recorded the highest concentrations of OCPs and PCBs, respectively. Moreover, OCPs residues had a significant relationship with agriculture and orchard land-use types, whereas PCBs residues occurred more in wasteland. Lifetime carcinogenic and non-carcinogenic risks of OCPs and PCBs through ingestion, inhalation, and dermal contact indicated that OCPs and PCBs residues in surface soils are at a low risk level.

Reliability analysis for dependent competing failure processes with changing degradation rate and hard failure threshold levels

Abstract Many systems are often subject to degradation and random shocks simultaneously, and their failure is the competing results of soft and hard failures. Motivated by the example of reinforced concrete (RC) pier columns of sea bridges, which experience dependent corrosion process and vessel collision-induced random shocks, shocks are divided into harmless ones and harmful ones according to their magnitude. Considering the impact of harmful shocks on temporal degradation performance, degradation rates as well as hard failure threshold levels, this paper proposes a new reliability model for systems subject to dependent competing failure processes. Hard failure occurs according to the combination of extended extreme shock model and extended δ -shock model, where the threshold level in the extended extreme shock model will be decreased by previous harmful shocks, and the threshold level in the extended δ -shock model depends on the magnitude of the previous harmful shock. Furthermore, each harmful shock will accelerate the degradation process by causing abrupt increase on degradation performance and acceleration on degradation rate. System reliability model is developed through analytical derivation and numerical calculation methods. Finally, a numerical study of RC pier columns of sea bridges is conducted to illustrate the implementation of the proposed model.

Anthropogenic impacts on forest land use and land cover change: Modelling future possibilities in the Himalayan Terai

Abstract The northern part of West Bengal, India partially falls within the Terai region of Himalaya. This region is distinctive in terms of high forest cover and rich biodiversity, but also features increasing human population, agricultural practices, and subsequent human-wildlife conflict. This study evaluated the impact of anthropogenic and agricultural proliferation on land use and land cover (LULC) transition dynamics of a forest and its surrounding area of this region. Jaldapara National Park along with its neighbouring region represents an ideal example of such ecology and thus was chosen as the study area. Satellite remote sensing was used to overcome accessibility issues in areas of protected forest and model future possible LULC of the area. Results indicated a continuous decrease in dense forest from 1978 to 2016. Modelling predicted a continuation of the same trend through 2050. The total area under forest increased from 1978 to 2001, possibly due to declaration of a part of the forest as a wildlife sanctuary in 1976 and subsequent increase in supervision and surveillance. However, total forest area started to decline from 2001 and future reductions are possible. Cultivated lands increased from 1978 to 2016 and additional future increase is likely due to a commensurate surge in human population in areas adjacent to the forest. In sum, increasing population pressure, agricultural production demands, and high human intervention in forest ecology were identified as possible causes of temporal forest degradation.

Acidity promotes degradation of multi-species environmental DNA in lotic mesocosms

Accurate quantification of biodiversity is fundamental to understanding ecosystem function and for environmental assessment. Molecular methods using environmental DNA (eDNA) offer a non-invasive, rapid, and cost-effective alternative to traditional biodiversity assessments, which require high levels of expertise. While eDNA analyses are increasingly being utilized, there remains considerable uncertainty regarding the dynamics of multispecies eDNA, especially in variable systems such as rivers. Here, we utilize four sets of upland stream mesocosms, across an acid–base gradient, to assess the temporal and environmental degradation of multispecies eDNA. Sampling included water column and biofilm sampling over time with eDNA quantified using qPCR. Our findings show that the persistence of lotic multispecies eDNA, sampled from water and biofilm, decays to non-detectable levels within 2 days and that acidic environments accelerate the degradation process. Collectively, the results provide the basis for a predictive framework for the relationship between lotic eDNA degradation dynamics in spatio-temporally dynamic river ecosystems.

Systematic study of spatiotemporal influences on temporal contrast in the focal region in large-aperture broadband ultrashort petawatt lasers

Temporal contrast is one of the crucial physical determinants which guarantee the successful performance of laser–matter interaction experiments. We generally reviewed the influences on the temporal contrast in three categories of noises based on the requirement by the physical mechanisms. The spatiotemporal influences on temporal contrast at the focal region of the chromatic aberration and propagation time difference introduced by large-aperture broadband spatial filters, which were spatiotemporally coupled with compression and focusing, were calculated and discussed with a practical case in SG-II 5 PW ultrashort petawatt laser. The system-wide spatiotemporal coupling existing in large-aperture broadband ultrashort petawatt lasers was proved to be one of the possible causes of temporal contrast degradation in the focal region.

A Massively Parallel Reporter Assay of 3′ UTR Sequences Identifies In Vivo Rules for mRNA Degradation

The stability of mRNAs is regulated by signals within their sequences, but a systematic and predictive understanding of the underlying sequence rules remains elusive. Here we introduce UTR-seq, a combination of massively parallel reporter assays and regression models, to survey the dynamics of tens of thousands of 3' UTR sequences during early zebrafish embryogenesis. UTR-seq revealed two temporal degradation programs: a maternally encoded early-onset program and a late-onset program that accelerated degradation after zygotic genome activation. Three signals regulated early-onset rates: stabilizing poly-U and UUAG sequences and destabilizing GC-rich signals. Three signals explained late-onset degradation: miR-430 seeds, AU-rich sequences, and Pumilio recognition sites. Sequence-based regression models translated 3' UTRs into their unique decay patterns and predicted the invivo effect of sequence signals on mRNA stability. Their application led to the successful design of artificial 3' UTRs that conferred specific mRNA dynamics. UTR-seq provides a general strategy to uncover the rules of RNA cis regulation.