High Rate Tracking Research Articles

Development of Micro-Pattern Gaseous Detectors for Nuclear Reaction Studies

One of the frontiers of today’s nuclear physics research is the synthesis of Super Heavy Elements (SHE). Fusion-fission dynamics, namely the competition between quasi fission and fusion is one of the key challenges to optimize the SHE. To have an insight into the dynamics, one requires the study of fission fragment mass and angular distribution near barrier energies for heavy-ion induced fission reactions. Recent successful installation of linear accelerators in India offers a unique opportunity to study the dynamics of nuclear reactions and formation process of SHE. For the effective utilization of these current, as well as upcoming facilities, development of novel detectors to study reaction dynamics, formation process of SHE with heavier projectiles and higher beam energies is needed. Gaseous detectors have undergone a rapid improvement in terms of spatial, temporal and energy resolution, rate capability, radiation hardness, ion feedback etc., ushering in a new genre of micro-structured devices based on semi-conductor technology, commonly known as Micro-Pattern Gaseous Detectors (MPGDs). Although many of the MPGD structures were primarily developed for high-rate tracking of charged particles in high energy physics experiments, stability of operation, simplicity of construction and relatively low cost make these detectors suitable for other applications, such as low-energy nuclear physics experiments. The present activities encompass a detailed evaluation of the operational conditions of Micromesh-Multi Wire and THGEM-Multi Wire hybrid detector operated in low-pressure isobutane gas with a view to optimizing their use in the detection of charged particles and fission fragments.

Fiducial markers for stereotactic lung radiation therapy: review of the transthoracic, endovascular and endobronchial approaches.

Stereotactic body radiation therapy is an alternative to surgery for early-stage, inoperable peripheral non-small cell lung cancer. As opposed to linear accelerator (linac)-based (e.g. gating) and free-breathing techniques, CyberKnife® with Synchrony® technology allows accurate radiation delivery by means of a real-time respiratory motion tracking system using, in most cases, metal fiducial markers (FMs) placed in the vicinity of the target. The aims of this review are as follows. First, to describe the safety and efficacy of the transthoracic, endovascular and endobronchial FM insertion techniques for peripheral pulmonary lesions (PPLs). Second, to analyse performance in terms of the migration and tracking rates of different FM types. Recent developments in FM tracking for central lesions will also be reviewed. In conclusion, for PPLs, the endobronchial approach provides a low rate of pneumothorax, offers the possibility of concurrent diagnostic sampling for both the PPL and the lymph nodes, and, finally, reduces the intervention time compared to other techniques. In this context, coil-tailed and coil-spring FMs have shown the lowest migration rate with a consequently high tracking rate.

Cooling and Timing Tests of the ATLAS Fast TracKer VME Boards

The Fast TracKer (FTK) is an ATLAS trigger upgrade built for full-event, low-latency, high-rate tracking. The FTK core, made of 9U VME boards, performs the most demanding computational task. The associative memory board (AMB) serial link processor and the auxiliary card (AUX), plugged on the front and back sides of the same VME slot, constitute the processing unit (PU), which finds tracks using hits from eight layers of the inner detector. The PU works in pipeline with the second stage board (SSB), which finds 12-layer tracks by adding extra hits to the identified tracks. In the designed configuration, 16 PUs and four SSBs are installed in a VME crate. The high power consumption of the AMB, AUX, and SSB (respectively, of about 250, 70, and 160 W per board) required the development of a custom cooling system. Even though the expected power consumption for each VME crate of the FTK system is high compared with a common VME setup, the 8 FTK core crates will use ≈60 kW, which is just a fraction of the power and the space needed for a CPU farm performing the same task. We report on the integration of 32 PUs and eight SSBs inside the FTK system, on the infrastructures needed to run and cool them, and on the tests performed to verify the system processing rate and the temperature stability at a safe value.

On the exact recovery conditions of 3D human motion from 2D landmark motion with sparse articulated motion

In this paper, we address the problem of exact recovery condition in retrieving 3D human motion from 2D landmark motion. We use a skeletal kinematic model to represent the 3D motion as a vector of angular articulation motion. We address this problem based on the observation that at high tracking rate, regardless of the global rigid motion, only few angular articulations have non-zero motion. We propose a first ideal formulation with ℓ0-norm to minimize the cardinal of non-zero angular articulation motion given an equality constraint on the time-differentiation of the reprojection error. The second relaxed formulation relies on an ℓ1-norm to minimize the sum of absolute values of the angular articulation motion. This formulation has the advantage of being able to provide 3D motion even in the under-determined case when twice the number of 2D landmarks is smaller than the number of angular articulations. We define a specific property which is the Projective Kinematic Space Property (PKSP) that takes into account the reprojection constraint and the kinematic model. We prove that, for the relaxed formulation, we are able to recover the exact 3D human motion from 2D landmarks if and only if the PKSP property is verified. We further demonstrate that solving the relaxed formulation provides the same ground-truth solution as the ideal formulation if and only if the PKSP condition is filled. Results with simulated sparse skeletal angular motion show the ability of the proposed method to recover exact location of angular motion. We provide results on publicly available real data (Human3.6M, Panoptic, MPI-I3DHPand 3DPW) and show that our method is able to achieve state-of-the-art 3D reconstructions.

A simple method to characterize high rate twin boundary kinetics in Ni-Mn-Ga

Experimental characterization of twin boundary kinetics is essential to systematically test and reproduce the actuation properties of Magnetic Shape Memory (MSM) elements at high rates. Here, we present a simple, nondestructive, experimental method to quantify the dynamic response of an MSM crystal and extract the major material properties that govern its kinetics. The tested sample is subjected to a mechanical pulse that is produced by a simple off-the-shelf solenoid. The mechanical pulse leads to actuation of the tested MSM Ni–Mn–Ga single crystal within 10 ms, during which the twin boundary velocity varies between zero and 2 m/s. The displacement and force in the MSM crystal are measured simultaneously using an optical sensor and a miniature force sensor, respectively. The data captured during a single loading experiment allow plotting a dynamic stress-strain curve as well as a kinetic relation that characterizes the macroscopic response of the crystal. In particular, the obtained kinetic relation enables the extraction of the transition driving force between slow (thermally activated) and fast (athermal) twin boundary motions. This transition driving force is a key material property that governs fast actuation capabilities of MSM elements. The macroscopic behavior of the sample is correlated with the motion of individual twin boundaries within the crystal by adding high speed microscopy to the experimental setup. This allows simultaneous high-rate tracking of individual twinning interfaces in Ni–Mn–Ga.

Spatial patterns and drivers of invasive rodent dynamics in New Zealand forests

Populations of invasive ship rat (Rattus rattus) and house mouse (Mus musculus) vary greatly over both time and space in New Zealand’s indigenous forests. Both species threaten endemic fauna, and their spatiotemporal variation over short time scales and steep environmental gradients present substantial challenges for conservation management. We fitted models to 18 years of 3-monthly records from a large-scale tracking-tunnel network to (1) predict, classify and describe forest-wide spatial patterns of temporal dynamics of unmanaged rat and mouse populations, and (2) understand the population-limiting roles of environment and biotic interactions. We distinguish six classes of forest rodent dynamics by classifying deciles of predicted rat-tracking rates. Classes form sequences across broad latitudinal and elevation gradients, and grade from ‘irruptive’, with low median but synchronous high maximum rat and mouse tracking rates in colder forests, to ‘continuously ratty’, with high median rat and low unsynchronised mouse tracking rates in warmer forests. Mice irrupt alone more frequently in colder forests, and their tracking rates are spatially reciprocal with rat tracking rate minima but not maxima. We conclude that predictable spatial patterns of rodent population dynamics arise from stronger low-temperature limitations on rats than mice, biotic limitation of mice by rats, and spatiotemporal food resource patterns affecting both species. Practical implications are that native species conservation in New Zealand forests requires spatially-differentiated predator management regimes; ship rats are likely to become increasingly prevalent at higher elevations as climate warms; and suppression of ship rats alone will release house mouse populations, especially in warmer forests.

New technique for online object tracking‐by‐detection in video

Object detection and tracking is an important task within the field of computer vision, because of its promising application in many areas, such as video surveillance. The need for automated video analysis has generated a great deal of interest in the area of motion tracking. A new technique is proposed for online object tracking-by-detection capable of achieving high detection and tracking rates, using a stationary camera, in a particle filtering framework. The fundamental innovation is that the detection technique integrates the local binary pattern texture feature, the red green blue (RGB) colour feature and the Sobel edge feature, using ‘Choquet’ fuzzy integral to avoid uncertainty in the classification. This is performed by extracting the colour and edge grey scale confidence maps and introducing the texture confidence map. Then, the tracking technique makes use of the continuous confidence detectors, extracted from those confidence maps, along with another three introduced classifier confidence maps, extracted from an online boosting classifier. Finally, both the confidence detectors and the classifier maps are integrated in the particle filtering framework, using the Choquet integral. Experimental results for both indoor and outdoor dataset sequences confirmed the robustness of the proposed technique against illumination variation and scene motion.

Evaluation of Lung Ventilation and Strain From Direct Measurements of Lung Deformation During Breathing Using Hyperpolarized Helium-3 Tagging MRI

Results: For the 59 images analyzed, the template-based matching algorithm was able to localize the GTV on only 74.6% (44/59) of the SE images vs. 94.9% (56/59) of the DE images (p Z 0.004). For 3 cases, the algorithm was unable to localize the GTVon both the SE and DE images. In the 12 cases in which the algorithm localized the GTVon the DE image but not on the SE image, 8 of the GTVs were < 5 cc in volume (pZ 0.39). Median vector differences in the position of the GTV centroids for the template-based match and the “ground truth” images were 0.5 mm (95% CIZ 0.3 mm, 1.0 mm) for SE images, versus 0.6 mm (95% CIZ 0.4 mm, 1.0 mm) for DE images (p Z 0.63). Conclusions: While the accuracy is comparable, DE imaging provides a higher tracking rate than SE imaging using a template-based matching algorithm on kV planar images for patients with lung tumors. By combining such an algorithm with DE imaging, this approach has the potential to allow for accurate and reliable real-time, markerless-motion tracking of lung tumors. Author Disclosure: A.M. Block: None. R. Patel: E. Research Grant; Varian Medical Systems. J. Panfil: E. Research Grant; Varian Medical Systems. J. Breunig: None. M. Surucu: None. M.M. Harkenrider: None. J.C. Roeske: E. Research Grant; Varian Medical Systems.

Evaluation of 4D Cone Beam Computed Tomography for Target Localization in Stereotactic Body Radiation Therapy for Early Lung Cancer

Results: For the 59 images analyzed, the template-based matching algorithm was able to localize the GTV on only 74.6% (44/59) of the SE images vs. 94.9% (56/59) of the DE images (p Z 0.004). For 3 cases, the algorithm was unable to localize the GTVon both the SE and DE images. In the 12 cases in which the algorithm localized the GTVon the DE image but not on the SE image, 8 of the GTVs were < 5 cc in volume (pZ 0.39). Median vector differences in the position of the GTV centroids for the template-based match and the “ground truth” images were 0.5 mm (95% CIZ 0.3 mm, 1.0 mm) for SE images, versus 0.6 mm (95% CIZ 0.4 mm, 1.0 mm) for DE images (p Z 0.63). Conclusions: While the accuracy is comparable, DE imaging provides a higher tracking rate than SE imaging using a template-based matching algorithm on kV planar images for patients with lung tumors. By combining such an algorithm with DE imaging, this approach has the potential to allow for accurate and reliable real-time, markerless-motion tracking of lung tumors. Author Disclosure: A.M. Block: None. R. Patel: E. Research Grant; Varian Medical Systems. J. Panfil: E. Research Grant; Varian Medical Systems. J. Breunig: None. M. Surucu: None. M.M. Harkenrider: None. J.C. Roeske: E. Research Grant; Varian Medical Systems.

Robust Optimization in Intensity Modulated Proton Therapy Reduces Dose Variation Due to Setup Uncertainty and Anatomy Change

Results: For the 59 images analyzed, the template-based matching algorithm was able to localize the GTV on only 74.6% (44/59) of the SE images vs. 94.9% (56/59) of the DE images (p Z 0.004). For 3 cases, the algorithm was unable to localize the GTVon both the SE and DE images. In the 12 cases in which the algorithm localized the GTVon the DE image but not on the SE image, 8 of the GTVs were < 5 cc in volume (pZ 0.39). Median vector differences in the position of the GTV centroids for the template-based match and the “ground truth” images were 0.5 mm (95% CIZ 0.3 mm, 1.0 mm) for SE images, versus 0.6 mm (95% CIZ 0.4 mm, 1.0 mm) for DE images (p Z 0.63). Conclusions: While the accuracy is comparable, DE imaging provides a higher tracking rate than SE imaging using a template-based matching algorithm on kV planar images for patients with lung tumors. By combining such an algorithm with DE imaging, this approach has the potential to allow for accurate and reliable real-time, markerless-motion tracking of lung tumors. Author Disclosure: A.M. Block: None. R. Patel: E. Research Grant; Varian Medical Systems. J. Panfil: E. Research Grant; Varian Medical Systems. J. Breunig: None. M. Surucu: None. M.M. Harkenrider: None. J.C. Roeske: E. Research Grant; Varian Medical Systems.

Factor graph aided multiple hypothesis tracking

Since closely moving targets exist extensively in the ground moving target tracking, the uncertainty of data association greatly increases making the measurement-to-track association more difficult. Especially, traditional multiple hypothesis tracking (MHT) has high false tracking rate and track swap. This paper first investigates the measurement based factor graph in data association, and gives the corresponding message passing algorithm. Then, a factor graph aided multiple hypothesis tracking (FGA-MHT) method is proposed, which introduces factor graph based m-best hypothesis producing technique and exploits factor graph based probability refinement algorithm to reduce the uncertainty of measurement-to-track association. Experiment results demonstrate that FGA-MHT reduces times of track swap and increases the correct data association rate in closely moving target tracking.

Predicting post-release establishment using data from multiple reintroductions

For any reintroduction it is important to maximise the probability of released individuals establishing in the target area (settling and surviving to breed). Factors influencing establishment have typically been studied at single sites, making it impossible to assess factors that vary at the site level (e.g. connectivity) or quantify unpredictable variation among sites. Using data from 14 reintroductions of the North Island robin (Petroica longipes) to native forest reserves, we show how Bayesian modelling can be used to identify general drivers of establishment and to account for site-to-site variation when making predictions for new sites. High landscape connectivity and high rat tracking rates (a density index) at reintroduction sites were key factors associated with lower individual establishment probabilities. Habitat similarity between source and release sites was also important, as robins sourced from native forest had higher establishment than those from exotic pine forest. Previous predator experience appeared to affect establishment in sites with mammalian predators, as founders sourced from sites with these predators had higher establishment than those from other sites. Our approach can be applied to a wide range of species that are being reintroduced to multiple sites, providing guidance on source and release site selection, efficacy of management interventions, and the numbers of individuals to release to achieve desired initial population sizes. The results are not only applicable to these particular species, but can be used to predict site suitability for reintroductions of species with similar dispersal behaviour or other ecological characteristics.

Adaptive Equalization Algorithms: An Overview

The recent digital transmission systems impose the application of channel equalizers with short training time and high tracking rate. Equalization techniques compensate for the time dispersion introduced by communication channels and combat the resulting inter-symbol interference (ISI) effect. Given a channel of unknown impulse response, the purpose of an adaptive equalizer is to operate on the channel output such that the cascade connection of the channel and the equalizer provides an approximation to an ideal transmission medium. Typically, adaptive equalizers used in digital communications require an initial training period, during which a known data sequence is transmitted. A replica of this sequence is made available at the receiver in proper synchronism with the transmitter, thereby making it possible for adjustments to be made to the equalizer coefficients in accordance with the adaptive filtering algorithm employed in the equalizer design. In this paper, an overview of the current state of the art in adaptive equalization techniques has been presented.

Improved kHz-SLR tracking techniques and orbit quality analysis for LEO missions

Satellite gravity field missions such as CHAMP, GRACE and GOCE are designed as low Earth orbiting spacecraft (LEO) with orbit heights of about 250–500 km. The challenging mission objectives require a very precise knowledge of the satellite orbit position in space. For these missions precise orbit information is typically provided by GPS satellite-to-satellite tracking (SST) observations supported by satellite laser ranging (SLR). The role of SLR is primarily devoted to serve as an independent tracking instrument used to calibrate and validate the on-board GPS flight receiver. However, the very limited visibility of LEOs from SLR ground stations together with the accordingly high angular rates necessary for the laser mounting to follow the satellite make it more difficult to track LEO missions. At the Observatory Graz–Lustbühel, the Space Research Institute of the Austrian Academy of Sciences operates a very novel SLR facility which was continuously upgraded during the recent years, and is today the only station worldwide capable to operate at kHz-firing rates. The activities presented here focus on a number of hardware upgrades and methodical improvements at the SLR station Graz aiming for a faster and more reliable target acquisition. These include upgrades of laser tracking algorithms as well as a redesign of the laser detection package in particular for LEO spacecraft. These improvements allow an extension of the measurement durations and thus increase the number of observations per pass. As a result we are able to raise the normal point accuracy as well as the overall system performance for LEO tracking. Improvements of the pointing accuracy and the range gate control system lead to a data quantity raise of about 5%. Another task addresses both a geometric and dynamic arc comparison of SLR derived orbits with GPS SST orbit solutions. In the case of CHAMP, the resulting one-way SLR range residuals are in the order of a few centimetres. This allows to draw conclusions on the accuracy of orbit solutions. In order to evaluate the performance of this technique for the upcoming GOCE mission, investigations are carried out in an analogous manner based on simulated GOCE SLR observations. In this study, it is demonstrated that satellite laser ranging, in particular with high-rate tracking capabilities and low orbit optimizations, offers a valuable tool for orbit validation purposes.

Pose Robust Face Tracking by Combining Active Appearance Models and Cylinder Head Models

The active appearance models (AAMs) provide the detailed descriptive parameters that are useful for various autonomous face analysis problems. However, they are not suitable for robust face tracking across large pose variation for the following reasons. First, they are suitable for tracking the local movements of facial features within a limited pose variation. Second, they use gradient-based optimization techniques for model fitting and the fitting performance is thus very sensitive to initial model parameters. Third, when their fitting is failed, it is difficult to obtain appropriate model parameters to re-initialize them. To alleviate these problems, we propose to combine the active appearance models and the cylinder head models (CHMs), where the global head motion parameters obtained from the CHMs are used as the cues of the AAM parameters for a good fitting or re-initialization. The good AAM parameters for robust face tracking are computed in the following manner. First, we estimate the global motion parameters by the CHM fitting algorithm. Second, we project the previously fitted 2D shape points onto the 3D cylinder surface inversely. Third, we transform the inversely projected shape points by the estimated global motion parameters. Fourth, we project the transformed 3D points onto the input image and computed the AAM parameters from them. Finally, we treat the computed AAM parameters as the initial parameters for the fitting. Experimental results showed that face tracking combining AAMs and CHMs is more pose robust than that of AAMs in terms of 170% higher tracking rate and the 115% wider pose coverage.

Long-term automated monitoring of the distribution of small carnivores

A new automated monitoring device for small carnivores, the Scentinel®, is a ‘smart’ tracking tunnel. It records time, date, weight and a digital photograph of every animal visiting it, and stores the data to be downloaded on command. This paper describes a field trial aiming, first, to verify the Scentinel’s species identifications against those given by footprint tracking papers, and then to compare the efficacy of routine monitoring with the Scentinel against standard tunnel tracking methods. In February–April 2005 we identified to species 98% of 1559 visiting animals, mainly hedgehogs (Erinaceus europaeus), ferrets (Mustela furo), cats (Felis catus) and rats (Rattus rattus and R. norvegicus) in 1718 Scentinel-nights. In May–June 2005 we set up three monitoring lines 1 km apart, each with 10 tracking tunnels and two Scentinels. We recorded 656 visits by ship rats (Rattus rattus), 88% of them on only one of the three lines, in 198 Scentinel-nights (over 5 weeks). The 30 footprint tracking tunnels set intermittently (360 trap-nights) recorded high (70–100%) tracking rates on all lines. The presence of a stoat (Mustela erminea) was detected by both methods, but earlier by Scentinels than by tracking tunnels. These results confirm that it is possible to use automated devices to record detailed monitoring data on small carnivores in remote areas over long periods, unaffected by interference or bait loss from common non-target species.

Clinical considerations for the allied professional: Programming issues in cardiac resynchronization therapy

grammed? Answer: The basic premise in CRT programming is to maintain a wide range of atrial-synchronous biventricular pacing: low base rate in patients without sinus node dysfunction, high upper tracking rate per age-based predicted heart rate, and optimal AV interval in VDD or DDD mode. 2. Can AV delay be optimized empirically? Answer: Sensed AV (S-AV) delay averaging 100 ms may be optimal in the majority of patients but should be confirmed with subjective clinical response. Paced AV (P-AV) delay is programmed 30 ms longer than S-AV delay. If intrinsic intraatrial delay or latency (stimulus-to-P) is noted, P-AV delay is increased so that the P wave is not truncated and atrial depolarization is completed at the onset of ventricular activation. 1 Various formulas are used in approximating optimal AV delay based on intrinsic ECG intervals, e.g., optimal S-AV PR (ms) 0.50 (if QRS 150 ms) or PR (ms) 0.70 (if QRS 150 ms). 2,3 3. What are objective measures of AV optimization? Answer: The measures used in clinical trials include Doppler echocardiography for the Ritter method using mitral velocity, aortic velocity-time integral (VTI), and stroke

Analysis and performance of the control systems of the NASA 70-meter antennas

The control systems of the NASA 70-m antennas include the antenna control system, the Master Equatorial (ME) control system, and their combinations (called modes). The Master Equatorial is a small telescope mounted on the top of a tower located inside the antenna structure. In the Antenna Encoder mode antenna encoders are used to close the feedback loop. In the Autocollimator mode the Master Equatorial is a master that follows a target, and the antenna is a slave that follows the Master Equatorial. In the Master Equatorial Encoder mode the “master-slave” relationship is reversed. In the paper the analysis begins with the description of the open-loop models of the antenna and of the Master Equatorial. We obtained the models by using field test data and system identification techniques. Next, we analyzed and evaluated the performance of the three modes of the antenna control system. The analysis showed that the Autocollimator and Master Equatorial Encoder tracking modes are feasible for high-rate tracking, and that the latter mode has the smallest tracking error. Finally, we analyzed the switching between antenna modes, necessary while tracking near the keyhold. We showed that switching causes jerks of magnitudes within the acceptable threshold. The contribution of this paper includes the development of the antenna model using field data and system identification procedures, the development of the LQG control algorithm for the 70-meter antenna, the development of two control cooperating systems (antenna and ME), identifying the more appropriate, and analyzing of switching between the two control systems.

Gas detectors: achievements and trends

We describe recent developments of two areas of research on gaseous detectors: resistive plate chambers, aiming at best time resolution, and micro-pattern chambers, designed for high-rate tracking in hostile environments. Emphasis is put on the progress in the basic understanding of the operating features, and of the underlying physical processes. Some examples of applications of detectors outside particle physics are also provided.

Progress with the gas electron multiplier

The Gas Electron Multiplier (GEM) amplifies electrons released in a gas and transfers them to a second element of detection, multiwire or microstrip chamber. We describe recent developments realized with two GEM meshes in series, followed by a simple printed circuit as read-out electrode. Full detection efficiency for minimum ionizing electrons has been obtained, with good energy and time resolution; bi-dimensional localization can be achieved recording the induced signals on orthogonal strips printed on a double-sided thin circuit. While with a single, 50-μm thick GEM mesh amplification factors around one hundred are attained, with a twin mesh having the facing electrodes in electrical contact (emulating a thicker GEM) we have obtained gains in excess of a thousand, large enough for efficient detection of radiation. We believe that this can lead to the development of a new generation of simple, reliable, cheap detectors for high-rate tracking and bi-dimensional imaging of radiation.