Temporal Bins Research Articles

Programmable Photonic Quantum Circuits with Ultrafast Time-Bin Encoding.

We propose a quantum information processing platform that utilizes the ultrafast time-bin encoding of photons. This approach offers a pathway to scalability by leveraging the inherent phase stability of collinear temporal interferometric networks at the femtosecond-to-picosecond timescale. The proposed architecture encodes information in ultrafast temporal bins processed using optically induced nonlinearities and birefringent materials while keeping photons in a single spatial mode. We demonstrate the potential for scalable photonic quantum information processing through two independent experiments that showcase the platform's programmability and scalability, respectively. The scheme's programmability is demonstrated in the first experiment, where we successfully program 362 different unitary transformations in up to eight dimensions in a temporal circuit. In the second experiment, we show the scalability of ultrafast time-bin encoding by building a passive optical network, with increasing circuit depth, of up to 36 optical modes. In each experiment, fidelities exceed 97%, while the interferometric phase remains passively stable for several days.

Climatology of the open–closed boundary using ULF wave observations from South Pole, McMurdo, and distributed Antarctic AGOs

It has been shown that a proxy determination of the magnetospheric open–closed magnetic field line boundary (OCB) location can be made by examining the ultra-low-frequency (ULF) wave power in magnetometer data, with particular interest in the Pc5 ULF waves with periods of 3–10 min. In this study, we present a climatology of such Pc5 ULF waves using ground-based magnetometer data from the South Pole Station (SPA), McMurdo (MCM) station, and the Automatic Geophysical Observatories (AGOs) located across the Antarctic continent, to infer OCB behavior and variability during geomagnetically quiet times (i.e., Ap < 30 nT). For each season [i.e., austral fall (20 February 2017–20 April 2017), austral winter (20 May 2017–20 July 2017), austral spring (20 August 2017–20 October 2017), and austral summer (20 November 2017–20 January 2018)], north–south (i.e., H-component) magnetic field line residual power–spectral density (PSD) measurements taken during geomagnetically quiet periods within a 60-day window centered at the austral solstice/equinox are averaged in 10-min temporal bins to form the climatology at each station. These residual PSDs thus enable the analysis of Pc5 activity (and lower period “long-band” oscillations) and, thus, OCB location/variability as a function of season and magnetic latitude. The dawn and dusk transitions across the OCB are analyzed, with a discussion of dawn and dusk variability during nominally quiet geomagnetic periods. In addition, latitudinal dependencies of the OCB and peak Pc5 periods at each station are discussed, along with the empirical Tsyganenko model comparisons to our site measurements.

The Characteristics of the Abnormal Day-to-Day TEC Variation above East Asian Region

We investigate the abnormal day-to-day variability of total electron content (TEC) over 60 Global Navigation Satellite System (GNSS) stations above the East Asian region from 2012 to 2018 and find that the positive anomalies occur more frequently at the middle latitude at about LT 14–20 and occur frequently around 28° N at about LT 22–00. The negative anomalies occur more frequently at the middle latitude at LT 10–02, and they obviously occur less frequently at about 15° N~30° N and LT 08–12, and occur less frequently near about 22° N~30° N and LT 14–18. The quantities of positive anomalies and negative anomalies are comparable. The direction of moving anomalies is from east to west in a zonal direction in all conditions. The moving speeds of anomalies are around 15~19 degrees per hour in the zonal direction and seem to grow as the latitude increases. TEC anomalies occur in 22.1% of temporal bins before large earthquakes within seven days and occur in 24% of temporal bins in the interval, which is within one day before and three days later than the main phase of geomagnetic storms. Further work is necessary to determine the sources of these anomalies.

Measurement of the muon lifetime and the Michel spectrum in the LAGO water Cherenkov detectors as a tool to enhance the signal-to-noise ratio

The Latin American Giant Observatory (LAGO) consists of a network of water Cherenkov detectors (WCDs) installed in the Latin American region at various latitudes, from Sierra Negra in Mexico, 18°59′ N 97°18′ W to the Antarctic Peninsula, 64°14′ S 56°38′ W and altitudes from Lima, Peru at 20m a.s.l. to Chacaltaya, Bolivia at 5500m a.s.l.The detectors of the network are built from commercial water tanks, so they have several geometries (cylindrical in general) and different water purification methods. All these features generate different profiles in the response to air shower particles measured by our detectors and produce pulse-shaped electronic signals. Common sources of noise in a WCD come from light leakage, electronic noise, and noise associated with the operation of photomultiplier tubes (PMTs) such as thermionic emission and after-pulses; they all could produce detectable pulses recorded by the LAGO data acquisition (DAQ) system. In LAGO WCDs, these noise signals are expected to present a short pulse width (of a few nanoseconds), while secondary radiation typically produces pulses of several tens of nanoseconds.We used data from the LAGO DAQ system, which digitises pulses at 40MHz sampling rate on windows of 300ns (12 temporal bins) and with a 10-bit resolution. The LAGO DAQ configuration uses a single threshold-based trigger in the third temporal bin. We proposed a secondary trigger threshold at the fourth bin to improve the noise rejection. In this work, we show how the optimal values for these triggers are now obtained from the measurement of the muon lifetime within the water volume and the resulting Michel spectrum. Our results were also simulated using the LAGO ARTI simulation framework to estimate the expected flux of secondary particles at the detector site; and the Meiga framework, a Geant4-based simulator used to estimate the WCDs response to the atmospheric radiation flux.

Monitors with Memories: Death Assemblages Record a Century of Wastewater Pollution and Remediation

Biotic indices are often used to assess ecological condition using the abundance-weighted stress tolerances of taxa. Applying such indices to recent fossil records – e.g., time-averaged death assemblages (DAs) – is a promising method to (1) characterize conditions from before monitoring began, and (2) detect otherwise unappreciated strain using discordance with the living assemblage (LA). However, the robustness of regionally-specific biotic indices when applied to paleoecological data is under-explored. Here, I assess the power of three indices: Southern California’s Benthic Response Index (BRI), ATZI’s Marine Benthic Index (AMBI), and BENTIX. Our test material is (a) a 50-year-long dataset of macrobenthos from the Palos Verdes shelf in Southern California, sampled annually at 44 sites to monitor the effects of treated wastewater effluent, and (b) bivalve DAs from the 2008 survey. The time series was parsed into temporal bins based on wastewater treatment phases, and we calculated indices for the whole fauna, bivalve LAs, and bivalve DAs. All indices demonstrated that benthic conditions improved with remediation, and the greatest changes were close to the outfall source. Values generated for bivalves were strongly correlated to those of the whole fauna, indicating that bivalves are a strong surrogate for macrobenthic condition (second only to polychaetes when compared among other clades). Indices for bivalve DAs – which include shells >100s yrs old on this shelf – indicated less strain than was observed in early communities (1970s-80s) and either agreed with or overestimated the strain in more recent communities (2000s-10s). This live-dead discordance suggests that time-averaging causes DAs to retain a signal from pre-pollution benthic conditions that the shelf benthos is now re-attaining. Bivalve DAs, combined with long-term benthic time series data, can reveal both the existence and direction of change in ecological strain relative to historic conditions.

Machine Learning Framework for Real-Time Assessment of Traffic Safety Utilizing Connected Vehicle Data

Assessment of roadway safety in real-time is a necessary component for providing proactive safety countermeasures to ensure the continued safety and efficiency of roadways. A framework for utilizing data from connected vehicles and other probe sources is proposed in this study. Connected vehicles present an opportunity to provide live fingerprinting and activity monitoring on roadways. Taking advantage of high-resolution trajectory data streaming directly from connected vehicles, variables are extracted and the relationship with crashes are explored utilizing statistical and machine learning models. Hard acceleration events, in conjunction with segment miles are shown to have strong positive correlations with historical crash outcomes as proven by OLS, Poisson and Gradient Booster regression models. An XGBoost classification model is then trained to predict the real-time instances of crash outcomes at 5 min temporal bins with high levels of accuracy when trained with data including the real-time segment speed, reference speed, segment miles, a segment crash risk factor and other variables related to the difference in speeds between consecutive segments as well as the hour of the day. A weighted ensemble model achieved the best performance with an accuracy of 0.95. The results present evidence that the framework can capitalize on the richness of data available via connected vehicles and is implementable as a component in Advanced Traffic Management Systems for the analysis of safety critical situations in real-time.

Cortical mechanisms of visual brightness.

SUMMARYThe primary visual cortex signals the onset of light and dark stimuli with ON and OFF cortical pathways. Here, we demonstrate that both pathways generate similar response increments to large homogeneous surfaces and their response average increases with surface brightness. We show that, in cat visual cortex, response dominance from ON or OFF pathways is bimodally distributed when stimuli are smaller than one receptive field center but unimodally distributed when they are larger. Moreover, whereas small bright stimuli drive opposite responses from ON and OFF pathways (increased versus suppressed activity), large bright surfaces drive similar response increments. We show that this size-brightness relation emerges because strong illumination increases the size of light surfaces in nature and both ON and OFF cortical neurons receive input from ON thalamic pathways. We conclude that visual scenes are perceived as brighter when the average response increments from ON and OFF cortical pathways become stronger.

Length‐weight relationships in 45 Neotropical fish species from the upper Tocantins River basin (Brazil)

We provide length-weight relationships (LWR) estimates for 45 species from the upper Tocantins River basin. Specimens were sampled by a standardized set of gill nets varying from 15 mm to 150 mm mesh size for 15 years (from 1995 to 2010) of field works. Field expeditions were carried out in three temporal bins with bimonthly samplings, (i) December 1995 to February 2000, (ii) February 2001 to December 2002, and (iii) February 2009 to December 2010, totalizing 46 field works. For all species, standard length (SL; 0.1 cm precision) and total weight (Wt; 0.01 g precision) were determined using a scale and a digital balance, respectively. From these 45 species, 28 have no previous LRW information in Fishbase, and we also provide new maximum standard length for 16 species. When data for at least 10 male or female individuals were available, we also provided the LWR information separately by gender.

Seeing the forest for the trees-and the grasses: revisiting the evidence for grazer-maintained grasslands in Madagascar's Central Highlands.

Seeing the forest for the trees-and the grasses: revisiting the evidence for grazer-maintained grasslands in Madagascar's Central Highlands.

A gridded surface current product for the Gulf of Mexico from consolidated drifter measurements

Abstract. A large set of historical surface drifter data from the Gulf of Mexico – 3770 trajectories spanning 28 years and more than a dozen data sources – are collected, uniformly processed and quality controlled, and assimilated into a spatially and temporally gridded dataset called GulfFlow. This dataset is available in two versions, with 1/4∘ or 1/12∘ spatial resolution respectively, both of which have overlapping monthly temporal bins with semimonthly spacing and which extend from the years 1992 through 2020. Together these form a significant resource for studying the circulation and variability in this important region. The uniformly processed historical drifter data from all publicly available sources, interpolated to hourly resolution, are also distributed in a separate product called GulfDriftersOpen. Forming a mean surface current map by directly bin-averaging the hourly drifter data is found to lead to severe artifacts, a consequence of the extremely inhomogeneous temporal distribution of the drifters. Averaging instead the already monthly-averaged data in GulfFlow avoids these problems, resulting in the highest-resolution map of the mean Gulf of Mexico surface currents yet produced. The consolidated drifter dataset is freely available at https://doi.org/10.5281/zenodo.3985916 (Lilly and Pérez-Brunius, 2021a), while the gridded products are available for noncommercial use only (for reasons discussed herein) at https://doi.org/10.5281/zenodo.3978793 (Lilly and Pérez-Brunius, 2021b).

Detecting strong spatial and temporal variation in macrobenthic composition on an urban shelf using taxonomic surrogates

Surrogates of macrobenthic assemblages, intended to alleviate the effort and taxonomic expertise required for monitoring, can take many forms, such as using coarser taxonomic levels (‘sufficiency’) or only a subset of the whole fauna (‘subsetting’). Here, the power of both approaches to retain community-level patterns of spatial and temporal variation were evaluated using an exceptionally long (47 yr) infaunal dataset generated from monitoring wastewater impacts on an urban shelf in southern California, USA. Four taxonomic sets (whole infauna, polychaetes, bivalves, malacostracans) were evaluated at 5 resolutions (species, genus, family, order, functional guild) along a pollution gradient subdivided into 2 spatial bins based on proximity to the wastewater outfall (near-field vs. far-field) and 3 temporal bins based on wastewater treatment phases. All taxonomic sets detected weakening of the spatial gradient with improved wastewater treatment, i.e. communities became more similar in richness, evenness, and composition through time, and patterns were robust when coarsened to families or guilds. Polychaetes mirrored (‘proxied’) whole-fauna patterns most accurately, as expected since they constitute most of the individuals and species. However, bivalves outperformed all other sets in detecting (‘indicating’) the pollution gradient itself, owing to their breadth of feeding strategies. These results strengthen the consistently positive results from taxonomic coarsening emerging from tests elsewhere and the caveats for taxonomic subsetting: clade strengths serve different objectives. Comparable datasets should exist in environmental agency archives elsewhere, promoting the general surrogacy model. For monitoring programs still in their planning stages, regional insights could be acquired via analogous nested analyses of a single survey.

0153 Patient-Defined Insomnia Severity: How Much Wakefulness is Problematic?

Abstract Introduction While Insomnia Disorder is formally defined in the ICSD-3 and DSM-5, neither diagnostic system adopts quantitative criteria for illness severity. Interestingly, quantitative criteria are provided for frequency and chronicity (i.e., ≥ 3 days / week for ≥ 3 months). For research purposes, illness severity has long been defined using the “30 minute rule” (SL and/or WASO and/or EMA of ≥ 30 minutes is the threshold for clinical relevance). In the present analysis, this threshold was assessed for its significance to patients. Methods Sleep continuity disturbance (SCD; SL, WASO, and EMA) and problem endorsement data were collected from an archival/community-based sample (N = 4680; 60% female; Ages 18–89 years; www.sleeplessinphilly.com). Problem endorsement was evaluated through questions that included, “Do you consider this a problem?” after participants reported length of SL, WASO, and EMA. Problem endorsement percentages were calculated for 5 minute bins for between 0 and 65 minutes, with one additional bin for > 65 minutes. The temporal bins were compared for significant deviations using absolute (percent of subjects at 0–5 and 5–10 minutes) and moving references (last significant percent). Results The first temporal bin to differ from the absolute reference for SL, WASO, and EMA was the 26–30 minute bin. At this threshold, 87%, 70%, and 94% of the subjects’ identifying SL, WASO and EMA as being problematic (and was deemed statistically different from “normal” [0–10 minute values]). Conclusion These data suggest that the “30 minute rule” (which is of unknown provenance) roughly corresponds to the level of illness severity (lowest common threshold) identified by patients as problematic. While the threshold for SL and EMA show a clear majority, the lower percentage of subjects for WASO suggests that people are more tolerant of middle of the night wakefulness. Support

Exploratory Spatiotemporal Language Analysis of Geo-Social Network Data for Identifying Movements of Refugees

Refugee movements in recent years have caused enormous challenges for relief organizations and public authorities, but especially for refugees themselves. Organizations which have to allocate their resources to regions where large groups of arrivals are expected struggle to prepare the refugees’ admission, transfer, care and accommodation in time. Events like the refugee movement of 2015/16 in Austria and Germany in the wake of the Syrian civil war have shown that many of these issues are caused by a lack of up-to-date information about logistical requirements. We evaluate various methods to acquire this information that utilize semantic, spatial and temporal features to analyse geo-social network data. A multimodal analysis of these features leads to information about refugee movements across borders and regions. Approaches based on user trajectories and attempts to identify refugees by the language they used showed little promise, whereas using spatiotemporal aggregation and hotspot analysis of keyword-based filtered data allowed us to retrace refugees’ collective movement patterns. Using temporal bins, we were able to detect changes in these patterns caused by external factors such as border closures.

Designing of Gabor filters for spectro-temporal feature extraction to improve the performance of ASR system

Existing automatic speech recognition (ASR) system uses the spectral or temporal features of speech. The performance of such systems is still poor compared to the human perception of hearing, especially in noisy environments. This paper concentrates on the extraction of spectro-temporal features based on physiological and psychoacoustically inspired approaches. Here, two dimensional Gabor filters are used to estimate the spectro-temporal features from time–frequency representation of uttered speech signals. The Gabor filters are designed using the concept of constant Q factor. It is found that human perception system maintains approximately constant Q in its frequency response along the chain of its filter bank. Constant Q analysis ensures that the Gabor filters occupy a set of geometrically spaced spectral and temporal bins. Time–frequency representation of speech signal is a key ingredient for Gabor based feature extraction method. For time–frequency mapping, Gammatonegram is adopted instead of conventional spectrogram representations. The performance of the ASR system with the proposed feature set is experimentally validated using AURORA2 noisy digit database. Under clean training; the proposed features obtained a relative improvement of about 50% in word error rate (WER) compared to Mel frequency cepstral coefficients (MFCC) features. A relative improvement of 23% in WER is also obtained compared with that of existing spectro-temporal feature extraction methods. Further analysis is carried out on TIMIT corrupted with noise samples taken from the NOISEX-92 database. The experimental verification proves the robustness of proposed features in building a robust acoustic model for the ASR system.

On the Use of Geophysical Parameters for the Top-of-Atmosphere Shortwave Clear-Sky Radiance-to-Flux Conversion in EarthCARE

AbstractWe have investigated whether differences across Clouds and the Earth’s Radiant Energy System (CERES) top-of-atmosphere (TOA) clear-sky angular distribution models, estimated separately over regional (1° × 1° longitude–latitude) and temporal (monthly) bins above land, can be explained by geophysical parameters from Max Planck Institute Aerosol Climatology, version 1 (MAC-v1), ECMWF twentieth-century reanalysis (ERA-20C), and a MODIS bidirectional reflectance distribution function (BRDF)/albedo/nadir BRDF-adjusted reflectance (NBAR) Climate Modeling Grid (CMG) gap-filled products (MCD43GF) climatology. Our research aimed to dissolve binning and to isolate inherent properties or indicators of such properties, which govern the TOA radiance-to-flux conversion in the absence of clouds. We collocated over seven million clear-sky footprints from CERES Single Scanner Footprint (SSF), edition 4, data with above geophysical auxiliary data. Looking at data per surface type and per scattering direction—as perceived by the broadband radiometer (BBR) on board Earth Clouds, Aerosol and Radiation Explorer (EarthCARE)—we identified optimal subsets of geophysical parameters using two different methods: random forest regression followed by a permutation test and multiple linear regression combined with the genetic algorithm. Using optimal subsets, we then trained artificial neural networks (ANNs). Flux error standard deviations on unseen test data were on average 2.7–4.0 W m−2, well below the 10 W m−2 flux accuracy threshold defined for the mission, with the exception of footprints containing fresh snow. Dynamic surface types (i.e., fresh snow and sea ice) required simpler ANN input sets to guarantee mission-worthy flux estimates, especially over footprints consisting of several surface types.

On Long‐Term SABER CO2 Trends and Effects Due to Nonuniform Space and Time Sampling

AbstractThe Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the TIMED satellite has been continuously operating for more than 16 years, since 2002, monitoring the CO2 concentration on nearly a global scale in the middle and upper atmosphere (from 65 km up to 110 km). A recent reanalysis (Qian et al., 2017, https://doi.org/10.1002/2016JA023825) concluded that different deseasonalizing methodologies may have a strong impact on long‐term trend analysis, ultimately yielding different altitude profiles of the global mean CO2 trend. In this work, we aim to understand how the nonuniform spatial and temporal sampling inherent in the SABER CO2 data set affects the determination of the long‐term trends. In addition, our goal is to disentangle reported differences in SABER CO2 trends due to different time averaging windows and methodologies used for trend estimation. The Whole Atmosphere Community Climate Model is used for synthetic studies of the time series. We demonstrate that, due to the time varying data gaps and nonuniform sampling of local times, different time binning of the SABER CO2 data may indeed bias the long‐term trend estimation. We show and discuss how the 60‐day averaging reduces the bias in relative trends. We also conclude that different deseasonalizing methodologies (averaged over the same temporal bins) yield negligible differences on the trend determination. Taking this into account the global mean CO2 relative trend does not deviate statistically from the tropospheric value below 1 × 10−3 mb (90 km). Above about 90 km, there is a positive slope in the global CO2 trend profile, but with substantially reduced magnitude for 60‐day binned data.

The greatest hits of all time: the histories of dominant genera in the fossil record

AbstractCertain taxa are noticeably common within collections, widely distributed, and frequently long-lived. We have examined these dominant genera as compared with rarer genera, with a focus on their temporal histories. Using occurrence data from the Paleobiology Database, we determined which genera belonging to six target groups ranked among the most common within each of 49 temporal bins based on occurrences. The turnover among these dominant taxa from bin to bin was then determined for each of these groups, and all six groups when pooled. Although dominant genera are only a small fraction of all genera, the patterns of turnover mimic those seen in much larger compilations of total biodiversity. We also found that differences in patterns of turnover at the top ranks among the higher taxa reflect previously documented comparison of overall turnover among these classes. Both dominant and nondominant genera exhibit, on average, symmetrical patterns of rise and fall between first and last appearances. Dominant genera rarely begin at high ranks, but nevertheless tend to be more common when they first appear than nondominant genera. Moreover, dominant genera rarely are in the top 20 when they last appear, but still typically occupy more localities than nondominant genera occupy in their last interval. The mechanism(s) that produce dominant genera remain unclear. Nearly half of dominant genera are the type genus of a family or subfamily. This is consistent with a simple model of morphological and phylogenetic diversification and sampling.

Temporal Response Properties of Accessory Olfactory Bulb Neurons: Limitations and Opportunities for Decoding.

The vomeronasal system (VNS) is a major vertebrate chemosensory system that functions in parallel to the main olfactory system (MOS). Despite many similarities, the two systems dramatically differ in the temporal domain. While MOS responses are governed by breathing and follow a subsecond temporal scale, VNS responses are uncoupled from breathing and evolve over seconds. This suggests that the contribution of response dynamics to stimulus information will differ between these systems. While temporal dynamics in the MOS are widely investigated, similar analyses in the accessory olfactory bulb (AOB) are lacking. Here, we have addressed this issue using controlled stimulus delivery to the vomeronasal organ of male and female mice. We first analyzed the temporal properties of AOB projection neurons and demonstrated that neurons display prolonged, variable, and neuron-specific characteristics. We then analyzed various decoding schemes using AOB population responses. We showed that compared with the simplest scheme (i.e., integration of spike counts over the entire response period), the division of this period into smaller temporal bins actually yields poorer decoding accuracy. However, optimal classification accuracy can be achieved well before the end of the response period by integrating spike counts within temporally defined windows. Since VNS stimulus uptake is variable, we analyzed decoding using limited information about stimulus uptake time, and showed that with enough neurons, such time-invariant decoding is feasible. Finally, we conducted simulations that demonstrated that, unlike the main olfactory bulb, the temporal features of AOB neurons disfavor decoding with high temporal accuracy, and, rather, support decoding without precise knowledge of stimulus uptake time.SIGNIFICANCE STATEMENT A key goal in sensory system research is to identify which metrics of neuronal activity are relevant for decoding stimulus features. Here, we describe the first systematic analysis of temporal coding in the vomeronasal system (VNS), a chemosensory system devoted to socially relevant cues. Compared with the main olfactory system, timescales of VNS function are inherently slower and variable. Using various analyses of real and simulated data, we show that the consideration of response times relative to stimulus uptake can aid the decoding of stimulus information from neuronal activity. However, response properties of accessory olfactory bulb neurons favor decoding schemes that do not rely on the precise timing of stimulus uptake. Such schemes are consistent with the variable nature of VNS stimulus uptake.

Spike-contrast: A novel time scale independent and multivariate measure of spike train synchrony

BackgroundSynchrony within neuronal networks is thought to be a fundamental feature of neuronal networks. In order to quantify synchrony between spike trains, various synchrony measures were developed. Most of them are time scale dependent and thus require the setting of an appropriate time scale. Recently, alternative methods have been developed, such as the time scale independent SPIKE-distance by Kreuz et al. New methodIn this study, a novel time-scale independent spike train synchrony measure called Spike-contrast is proposed. The algorithm is based on the temporal “contrast” (activity vs. non-activity in certain temporal bins) and not only provides a single synchrony value, but also a synchrony curve as a function of the bin size. ResultsFor most test data sets synchrony values obtained with Spike-contrast are highly correlated with those of the SPIKE-distance (Spearman correlation value of 0.99). Correlation was lower for data containing multiple time scales (Spearman correlation value of 0.89). When analyzing large sets of data, Spike-contrast performed faster. Comparison of existing methodSpike-contrast is compared to the SPIKE-distance algorithm. The test data consisted of artificial spike trains with various levels of synchrony, including Poisson spike trains and bursts, spike trains from simulated neuronal Izhikevich networks, and bursts made of smaller bursts (sub-bursts). ConclusionsThe high correlation of Spike-contrast with the established SPIKE-distance for most test data, suggests the suitability of the proposed measure. Both measures are complementary as SPIKE-distance provides a synchrony profile over time, whereas Spike-contrast provides a synchrony curve over bin size.

SU‐D‐9A‐01: Listmode‐Driven Optimal Gating (OG) Respiratory Motion Management: Potential Impact On Quantitative PET Imaging

Purpose:To evaluate the potential impact of listmode‐driven amplitude based optimal gating (OG) respiratory motion management technique on quantitative PET imaging.Methods:During the PET acquisitions, an optical camera tracked and recorded the motion of a tool placed on top of patients' torso. PET event data were utilized to detect and derive a motion signal that is directly coupled with a specific internal organ. A radioactivity‐trace was generated from listmode data by accumulating all prompt counts in temporal bins matching the sampling rate of the external tracking device. Decay correction for 18F was performed. The image reconstructions using OG respiratory motion management technique that uses 35% of total radioactivity counts within limited motion amplitudes were performed with external motion and radioactivity traces separately with ordered subset expectation maximization (OSEM) with 2 iterations and 21 subsets. Standard uptake values (SUVs) in a tumor region were calculated to measure the effect of using radioactivity trace for motion compensation. Motion‐blurred 3D static PET image was also reconstructed with all counts and the SUVs derived from OG images were compared with SUVs from 3D images.Results:A 5.7 % increase of the maximum SUV in the lesion was found for optimal gating image reconstruction with radioactivity trace when compared to a static 3D image. The mean and maximum SUVs on the image that was reconstructed with radioactivity trace were found comparable (0.4 % and 4.5 % increase, respectively) to the values derived from the image that was reconstructed with external trace.Conclusion:The image reconstructed using radioactivity trace showed that the blurring due to the motion was reduced with impact on derived SUVs. The resolution and contrast of the images reconstructed with radioactivity trace were comparable to the resolution and contrast of the images reconstructed with external respiratory traces.Research supported by Siemens