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Open Access Publications from the University of California

Scholarly Works (4 results)

  • Thesis
  • Peer Reviewed
UC Irvine Electronic Theses and Dissertations (2022)

Low Earth orbit (LEO) satellites inherently possess desirable attributes for navigation: (i) abundance, (ii) geometric and spectral diversity, and (iii) high received powers. However, the first prerequisite to satellite navigation is to know the satellites’ ephemeris (i.e., position and velocity over time) and clock error states. Unlike global navigation satellite systems (GNSS), specifically designed for navigation, with satellites in medium Earth orbit (MEO) that constantly transmit ephemeris and clock corrections to users in their signals, LEO satellites, mainly operated by private companies, generally do not openly send such information in their proprietary signals. The quality of oscillators on-board LEO satellites’ as well as their clock error states are completely unknown. Moreover, the most accurate publicly available information on LEO satellites’ ephemerides is in the form of two-line element (TLE) files, which yield ephemerides with errors of a few kilometers in position and a few meters per second in velocity. Consequently, LEO satellites’ states are completely unknown (clock errors) or uncertain at best (ephemeris).

This thesis addresses the aforementioned challenges by performing the opportunistic estimation of LEO satellites’ states. First, a study of the use of machine learning for satellite orbital determination is conducted. Multiple models for orbit propagation are analyzed, and the model with the best performance is found. The model is then utilized in a STAN framework, experimentally demonstrating its capability of producing satellite ephemeris good enough to allow for desirable navigation solutions. Next, a framework is proposed to collect training data when the target ephemeris data is not available due to satellites not transmitting their ephemeris. Finally, the framework’s feasibility is demonstrated experimentally first by localizing a stationary receiver and second by coupling an IMU with LEO observables to navigate a moving ground vehicle.

    Cover page: Towards Opportunistic Navigation with LEO Satellites: Machine Learning for Satellite Orbit Propagation
    • Article
    • Peer Reviewed
    UC Irvine Previously Published Works (2021)
      Cover page: Enter LEO on the GNSS Stage: Navigation with Starlink Satellites
      • Article
      • Peer Reviewed
      UCLA Previously Published Works (2016)
      The CRISPR/Cas technology enables targeted genome editing and the rapid generation of transgenic animal models for the study of human genetic disorders. Here we describe an autosomal recessive human disease in two unrelated families characterized by a split-foot defect, nail abnormalities of the hands, and hearing loss, due to mutations disrupting the SAM domain of the protein kinase ZAK. ZAK is a member of the MAPKKK family with no known role in limb development. We show that Zak is expressed in the developing limbs and that a CRISPR/Cas-mediated knockout of the two Zak isoforms is embryonically lethal in mice. In contrast, a deletion of the SAM domain induces a complex hindlimb defect associated with down-regulation of Trp63, a known split-hand/split-foot malformation disease gene. Our results identify ZAK as a key player in mammalian limb patterning and demonstrate the rapid utility of CRISPR/Cas genome editing to assign causality to human mutations in the mouse in <10 wk.
        Cover page: Exome sequencing and CRISPR/Cas genome editing identify mutations of ZAK as a cause of limb defects in humans and mice
        • Article
        • Peer Reviewed
        UC Irvine Previously Published Works (2016)
        BACKGROUND:BRCA1 interacting protein C-terminal helicase 1 (BRIP1) is one of the Fanconi Anaemia Complementation (FANC) group family of DNA repair proteins. Biallelic mutations in BRIP1 are responsible for FANC group J, and previous studies have also suggested that rare protein truncating variants in BRIP1 are associated with an increased risk of breast cancer. These studies have led to inclusion of BRIP1 on targeted sequencing panels for breast cancer risk prediction. METHODS:We evaluated a truncating variant, p.Arg798Ter (rs137852986), and 10 missense variants of BRIP1, in 48 144 cases and 43 607 controls of European origin, drawn from 41 studies participating in the Breast Cancer Association Consortium (BCAC). Additionally, we sequenced the coding regions of BRIP1 in 13 213 cases and 5242 controls from the UK, 1313 cases and 1123 controls from three population-based studies as part of the Breast Cancer Family Registry, and 1853 familial cases and 2001 controls from Australia. RESULTS:The rare truncating allele of rs137852986 was observed in 23 cases and 18 controls in Europeans in BCAC (OR 1.09, 95% CI 0.58 to 2.03, p=0.79). Truncating variants were found in the sequencing studies in 34 cases (0.21%) and 19 controls (0.23%) (combined OR 0.90, 95% CI 0.48 to 1.70, p=0.75). CONCLUSIONS:These results suggest that truncating variants in BRIP1, and in particular p.Arg798Ter, are not associated with a substantial increase in breast cancer risk. Such observations have important implications for the reporting of results from breast cancer screening panels.
          Cover page: No evidence that protein truncating variants in BRIP1 are associated with breast cancer risk: implications for gene panel testing.
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