Impacts of nonpoint source water pollution in Castroville, California

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Passive Multi-Target Tracking Using the Adaptive Birth Intensity PHD Filter

Passive multi-target tracking applications require the integration of multiple spatially distributed sensor measurements to distinguish true tracks from ghost tracks. A popular multi-target tracking approach for these applications is the particle filter implementation of Mahler's probability hypothesis density (PHD) filter, which jointly updates the union of all target state space estimates without requiring computationally complex measurement-to-track data association. Although this technique is attractive for implementation in computationally limited platforms, the performance benefits can be significantly overshadowed by inefficient sampling of the target birth particles over the region of interest. We propose a multi-sensor extension of the adaptive birth intensity PHD filter described in (Ristic, 2012) to achieve efficient birth particle sampling driven by online sensor measurements from multiple sensors. The proposed approach is demonstrated using distributed time-difference-of-arrival (TDOA) and frequency-difference-of-arrival (FDOA) measurements, in which we describe exact techniques for sampling from the target state space conditioned on the observations. Numerical results are presented that demonstrate the increased particle density efficiency of the proposed approach over a uniform birth particle sampler.Comment: 21st International Conference on Information Fusio

Terahertz generation using plasmonic photoconductive gratings

A photoconductive terahertz emitter based on plasmonic contact electrode gratings is presented and experimentally demonstrated. The nanoscale grating enables ultrafast and high quantum efficiency operation simultaneously, by reducing the photo-generated carrier transport path to the photoconductor contact electrodes. The presented photoconductor eliminates the need for a short-carrier lifetime semiconductor, which limits the efficiency of conventional photoconductive terahertz emitters. Additionally, the photo-absorbing active area of the plasmonic photoconductive terahertz emitter can be increased without a significant increase in the capacitive loading to the terahertz radiating antenna, enabling high quantum-efficiency operation at high pump power levels by preventing the carrier screening effect and thermal breakdown. A plasmonic photoconductive terahertz emitter prototype based on the presented scheme is implemented and integrated with dipole antenna arrays on a semi-insulating In 0.53 Ga 0.47 As substrate. Emitted terahertz radiation is characterized in a terahertz time-domain spectroscopy setup, measuring a terahertz pulse width of 590 fs full-width at half maximum in response to 150 fs pump pulses at 925 nm.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98624/1/1367-2630_14_10_105029.pd

Accuracy of inference on the physics of binary evolution from gravitational-wave observations

The properties of the population of merging binary black holes encode some of the uncertain physics of the evolution of massive stars in binaries. The binary black hole merger rate and chirp mass distribution are being measured by ground-based gravitational-wave detectors. We consider isolated binary evolution and explore how accurately the physical model can be constrained with such observations by applying the Fisher information matrix to the merging black hole population simulated with the rapid binary population synthesis code COMPAS. We investigate variations in four COMPAS parameters: common envelope efficiency, kick velocity dispersion, and mass loss rates during the luminous blue variable and Wolf--Rayet stellar evolutionary phases. We find that 1000 observations would constrain these model parameters to a fractional accuracy of a few percent. Given the empirically determined binary black hole merger rate, we can expect gravitational-wave observations alone to place strong constraints on the physics of stellar and binary evolution within a few years.Comment: 12 pages, 9 figures; version accepted by Monthly Notices of the Royal Astronomical Societ

HEY LARRY! INVESTIGATING INTERRUPTIONS IN FUTURE VERTICAL LIFT PLATFORMS

Using technology to improve human performance is critical to maximizing the benefits of future combat systems. This study explores the effects of interruptions during high and low cognitive load states when completing dynamic tasks. Furthermore, it provides insight into how to integrate artificial intelligence and virtual assistants into future aircraft effectively. This research and the following analysis provided the Holistic Situation Awareness and Decision Making (HSA-DM) program office with meaningful data and recommendations that will enable them to reduce the impact of interruptions while improving the performance of future pilots. Specifically, this study collected and examined heart rate variability, subjective cognitive load, flight metrics, interruption lag, and task resumption lag while participants piloted an aircraft and performed dynamic tasks in a flight simulator. There were three different modalities used to assist participants with completing interrupted tasks while performing their primary task. The research team determined that the tactile activated artificial intelligence was the most effective at reducing total interruption time while having the smallest effects on flight performance and cognitive load.Major, United States ArmyMajor, United States ArmyCaptain, United States ArmyCaptain, United States ArmyCaptain, United States ArmyApproved for public release. Distribution is unlimited

Comparative study of visual performance with tinted soft contact lenses vs. clear soft contact lenses and tinted spectacles under bright outdoor conditions; Phase II

Background: Research has clearly shown the advantages of performance tinted CL wear with regard to various measures of objective and subjective responses under various lighting conditions. The current study expanded upon these results. Methods: Subjects were 38 non-presbyopic emmetropes or slight ametropes with distance Snellen acuity of 20/20 or better while wearing -0.50 D spherical Acuvue 2 CLs. Measurements of 6m tachistoscopic stereoacuity and variable distance timed and tachistoscopic texture gradient recognition were obtained with subjects wearing clear CLs, tinted spectacles, and SportSight CLs. Lens modality and test sequence were randomized. Results: Stereoacuity results showed no statistically significant difference in stereolocalization when subjects were wearing clear CLs, SportSight CLs, or tinted spectacles. Texture gradient results using timed and tachistoscopic presentations demonstrated that it was more difficult for subjects to correctly identify the seam orientation at farther distances than nearer distances, and that subjects took more time to try to identify distant target orientation versus near target orientation. In addition, tachistoscopic presentations were not found to be significant with regard to correctness of responses at any distance with any lens modality. Subjective data indicated more physical comfort with either CL modality instead of tinted spectacles. SportSight CLs were also found to be the most visually comfortable modality, followed by tinted spectacles and then clear CLs. Furthermore, a general trend indicated that subjects felt they were able to perform best while wearing the SportSight CLs. This may partially be due to the fact that subjects noted fewer perceptions of stray light with SportSight CLs than with the other modalities. Likewise, subjects reported an equal number of perceived reflections while wearing SportSight CLs and clear CLs but significantly more while wearing tinted spectacles. Conclusion: Objective findings demonstrated that SportSight CLs provide similar performance with regard to distance depth perception and texture gradient recognition to tinted spectacles. Subjective data indicate that visual comfort of the SportSight CLs was superior to tinted spectacles and clear CLs. Additionally, a trend in subjective data demonstrated that the subjects perceived improved performance on the tests while wearing the SportSight CLs

A study investigating a season\u27s baseball performance while wearing SportSight soft contact lenses

Background: The use of spectacles with colored lenses in sports is well known. Athletes have worn such colored lenses in an attempt to enhance their performance for a number of years with promising results. The integration of wavelength specific filters into contact lenses may provide significant performance enhancement as well as the visual advantages usually afforded by contact lenses relative to spectacles. Methods: A small group (N=5) of collegiate baseball players were fitted with SportSight soft contact lenses and were asked to wear them during practices and games for half of a season. The players\u27 batting and fielding statistics from the first and second halves of the season were compared to each other and to those of non-participating team members. All of the subjects were existing soft contact lens wearers. Results: The test group demonstrated dramatic improvements in batting statistics while wearing the SportSight lenses. Their percentage of statistical improvement in each category far surpassed that of non-participating team members. Conclusion: The results of this pilot study imply that wearing SportSight soft contact lenses yields marked performance enhancement for baseball players. Future studies involving larger subject pools are warranted to thoroughly evaluate the possible statistical significance of these findings