Accounting for biological and physical sources of acoustic backscatter improves estimates of zooplankton biomass

Author Posting. © NRC Canada, 2008. This is the author's version of the work. It is posted here by permission of NRC Canada for personal use, not for redistribution. The definitive version was published in Canadian Journal of Fisheries and Aquatic Sciences 65 (2008): 1321-1333, doi:10.1139/F08-047.In order to convert measurements of backscattered acoustic energy to estimates of abundance and taxonomic information about the zooplankton community, all of the scattering processes in the water column need to be identified and their scattering contributions quantified. Zooplankton populations in the eastern edge of Wilkinson Basin in the Gulf of Maine in the Northwest Atlantic were surveyed in October 1997. Net tow samples at different depths, temperature and salinity profiles, and multiple frequency acoustic backscatter measurements from the upper 200 meters of the water column were collected. Zooplankton samples were identified, enumerated, and measured. Temperature and salinity profiles were used to estimate the amount of turbulent microstructure in the water column. These data sets were used with theoretical acoustic scattering models to calculate the contributions of both biological and physical scatterers to the overall measured scattering level. The output of these predictions shows that the dominant source of acoustic backscatter varies with depth and acoustic frequency in this region. By quantifying the contributions from multiple scattering sources, acoustic backscatter becomes a better measure of net-collected zooplankton biomass.This work was supported by the Office of Naval 540 Research (Grants #N00014-00-1-0052 and N00014-01-1-0166)

Forming a stable memory representation in the first year of life: Why imitation is more than child's play.

Although 9-month-old infants are capable of retaining temporally ordered information over long delays, this ability is relatively fragile. It may be possible to facilitate long-term retention by allowing infants to imitate event sequences immediately after their presentation. The effects of imitation on immediate and delayed recognition and on long-term recall were investigated using event-related potentials (ERPs) and elicited imitation, respectively. Mnemonic facilitation resulting from the opportunity to imitate was apparent using both assessments. ERP assessments at immediate and delayed recognition tests suggested that infants who were allowed to imitate had stronger memory representations of familiar stimuli relative to infants who only viewed the presentation of the events. In addition, infants who were allowed to imitate evidenced higher levels of ordered recall after 1 month relative to infants who only watched the experimenter’s demonstration. Therefore, imitation proved to have beneficial effects on explicit memory in 9 1 / 2 -month-olds, providing evidence of its effectiveness as a tool to augment mnemonic capabilities in infancy

2022 Upgrade and Improved Low Frequency Camera Sensitivity for CMB Observation at the South Pole

Constraining the Galactic foregrounds with multi-frequency Cosmic Microwave Background (CMB) observations is an essential step towards ultimately reaching the sensitivity to measure primordial gravitational waves (PGWs), the sign of inflation after the Big-Bang that would be imprinted on the CMB. The BICEP Array telescope is a set of multi-frequency cameras designed to constrain the energy scale of inflation through CMB B-mode searches while also controlling the polarized galactic foregrounds. The lowest frequency BICEP Array receiver (BA1) has been observing from the South Pole since 2020 and provides 30 GHz and 40 GHz data to characterize the Galactic synchrotron in our CMB maps. In this paper, we present the design of the BA1 detectors and the full optical characterization of the camera including the on-sky performance at the South Pole. The paper also introduces the design challenges during the first observing season including the effect of out-of-band photons on detectors performance. It also describes the tests done to diagnose that effect and the new upgrade to minimize these photons, as well as installing more dichroic detectors during the 2022 deployment season to improve the BA1 sensitivity. We finally report background noise measurements of the detectors with the goal of having photon noise dominated detectors in both optical channels. BA1 achieves an improvement in mapping speed compared to the previous deployment season.Comment: Proceedings of SPIE Astronomical Telescopes + Instrumentation 2022 (AS22

Assistive technology design and preliminary testing of a robot platform based on movement intention using low-cost brain computer interface

The process through which children learn about the world and develop perceptual, cognitive and motor skills relies heavily on object exploration in their physical world. New types of assistive technology that enable children with impairments to interact with their environment have emerged in recent years, and they could be beneficial for children's cognitive and perceptual skills development. Many studies have reported on brain computer interface (BCI) research. However, a conventional electroencephalography (EEG) system is generally bulky and expensive. It also requires special equipment and technical expertise to operate successfully. In this study, a compact low-cost EEG system was used to detect signals related to movement intention and control a mobile robot control. EEG signals of three non-disabled adults were acquired by the BCI system and the movement intention was classified during physical movement and motor imagery. The average classification accuracies achieved during testing were 56.4% for the motor imagery and 72.7% for the physical movement. The results show moderate classification accuracy for the motor imagery; however, the classification accuracy for the physical movement was high for all the subjects. Even though further improvement of the system is still needed, the experimental results demonstrated the feasibility of a BCI-based robotic system that is affordable and accessible for many people including children with disabilities. © 2017 IEEE