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Open Access Publications from the University of California

Scholarly Works (6 results)

  • Thesis
  • Peer Reviewed
UC Riverside Electronic Theses and Dissertations (2019)

Formation control and trajectory following using distributed optimization algorithms is validated in this thesis. The crazyflie platform is used for validating the algorithms. Then the implementations on different algorithms and different numbers of robots take place. Firstly, distributed optimization algorithm with general time-varying cost functions is implemented to make the crazyflies follow a line trajectory in a square formation. Then another distributed optimization algorithm with time-varying cost functions and nonidentical hessian is used to get the crazeflies follow a circle trajectory in a square formation. After achieving relatively high accuracy of implementation of the two distributed optimization algorithms, a target tracking task is performed to prove the feasibility of the algorithms. In all, this thesis explores a new way for distributed optimization algorithms on multi-agent systems such as UAVs.

    Cover page: Experimental Implementation of Distributed Time-Varying Optimization Algorithms Using Crazyflie PlatformCreative Commons 'BY' version 4.0 license
    • Thesis
    • Peer Reviewed
    UCLA Electronic Theses and Dissertations (2014)

    Taxis play an important role in urban transportation by fulfilling people's demand for auto services without turning them into auto owners. In this thesis, I use Geographic Positioning System (GPS) data generated by 12,000 taxis in November, 2012 to analyze the spatio-temporal travel pattern of taxis in Beijing. ArcGIS and python programming are employed for data processing and computing. The result of the passenger pick-up and drop-off analysis on November 30th, 2012 confirms the geographical imbalance phenomenon mentioned in previous studies. The thesis also examines taxi driver's behavior by income and finds that drivers of higher daily incomes operate in larger territories. Additionally, time and monetary costs of the same trips made in transit mode and taxi mode are compared using travel time estimated by Google Maps. In extremely smooth traffic, when people consider their time worth more than an average of 30 Yuan an hour, they are likely to use taxis instead of transit.

      Cover page: How Do Taxis Work in Beijing? An Exploratory Study of Spatio-Temporal Taxi Travel Pattern Using GPS Data
      • Article
      • Peer Reviewed
      UC Davis Previously Published Works (2020)

      Background

      Virtually all existing evidence linking access to firearms to elevated risks of mortality and morbidity comes from ecological and case-control studies. To improve understanding of the health risks and benefits of firearm ownership, we launched a cohort study: the Longitudinal Study of Handgun Ownership and Transfer (LongSHOT).

      Methods

      Using probabilistic matching techniques we linked three sources of individual-level, state-wide data in California: official voter registration records, an archive of lawful handgun transactions and all-cause mortality data. There were nearly 28.8 million unique voter registrants, 5.5 million handgun transfers and 3.1 million deaths during the study period (18 October 2004 to 31 December 2016). The linkage relied on several identifying variables (first, middle and last names; date of birth; sex; residential address) that were available in all three data sets, deploying them in a series of bespoke algorithms.

      Results

      Assembly of the LongSHOT cohort commenced in January 2016 and was completed in March 2019. Approximately three-quarters of matches identified were exact matches on all link variables. The cohort consists of 28.8 million adult residents of California followed for up to 12.2 years. A total of 1.2 million cohort members purchased at least one handgun during the study period, and 1.6 million died.

      Conclusions

      Three steps taken early may be particularly useful in enhancing the efficiency of large-scale data linkage: thorough data cleaning; assessment of the suitability of off-the-shelf data linkage packages relative to bespoke coding; and careful consideration of the minimum sample size and matching precision needed to support rigorous investigation of the study questions.
        Cover page: Assembly of the LongSHOT cohort: public record linkage on a grand scale
        • Article
        • Peer Reviewed
        UCLA Previously Published Works (2024)
        Subjects are often willing to pay a cost for information. In a procedure that promotes paradoxical choices, animals choose between a richer option followed by a cue that is rewarded 50% of the time (No Info) vs. a leaner option followed by one of two cues that signal certain outcomes: one always rewarded (100%) and the other never rewarded, 0% (Info). Since decisions involve comparing the subjective value of options after integrating all their features, preference for information may rely on cortico-amygdalar circuitry. To test this, male and female rats were prepared with bilateral inhibitory Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) in the anterior cingulate cortex, orbitofrontal cortex, basolateral amygdala, or null virus (control). We inhibited these regions after stable preference was acquired. We found that inhibition of the anterior cingulate cortex destabilized choice preference in female rats without affecting latency to choose or response rate to cues. A logistic regression fit revealed that previous choice predicted current choice in all conditions, however previously rewarded Info trials strongly predicted preference in all conditions except in female rats following anterior cingulate cortex inhibition. The results reveal a causal, sex-dependent role for the anterior cingulate cortex in decisions involving information.
          Cover page: A special role for anterior cingulate cortex, but not orbitofrontal cortex or basolateral amygdala, in choices involving information.
          • Article
          • Peer Reviewed
          UC Davis Previously Published Works (2021)

          Background

          Apatinib is a new generation of small molecule tyrosine kinase inhibitor, which can highly selectively inhibit phosphorylation of vascular endothelial growth factor receptor 2 (VEGFR-2). This study aimed to investigate the synergistic effects of apatinib and paclitaxel (PTX) on triple-negative breast cancer (TNBC) in vivo and in vitro, and to explore the molecular mechanism of the PI3K/p65/Bcl-xl pathway.

          Methods

          In vitro, 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide (MTT) method, flow cytometry (FCM), wound healing assay, and transwell matrix assay were conducted to measure the effects of apatinib and PTX on cell viability, apoptosis, migration, and invasion in TNBC cell line MDA-MB-468. Western blot (WB) was conducted to detect protein expression levels of PI3K, p65, and Bcl-xl after the application of apatinib and PTX. In vivo, MDA-MB-468 tumor-bearing nude mice were treated with apatinib and PTX, and tumor growth was observed.

          Results

          In vitro, apatinib and PTX could synergistically suppress the cell viability, the combined group had the most obvious effect. Apatinib and PTX could promote apoptosis and suppress migration and invasion of TNBC cells. Apatinib could reduce the expression of p-PI3K, p65, and Bcl-xl proteins (P<0.05). In vivo, apatinib and PTX could inhibit tumor size and weight of model mice, and the combined agents had a more significant effect.

          Conclusions

          Apatinib could enhance the anti-tumor effect of PTX on TNBC cells through the PI3K/p65/Bcl-xl molecular pathway, and apatinib combined with PTX might be a promising option for TNBC treatment.
            Cover page: Apatinib enhances the anti-tumor effect of paclitaxel via the PI3K/p65/Bcl-xl pathway in triple-negative breast cancer
            • Article
            • Peer Reviewed
            LBL Publications (2023)
            All-liquid molding can be used to transform a liquid into free-form solid constructs, while maintaining internal fluidity. Traditional biological scaffolds, such as cured pre-gels, are normally processed in solid state, sacrificing flowability and permeability. However, it is essential to maintain the fluidity of the scaffold to truly mimic the complexity and heterogeneity of natural human tissues. Here, this work molds an aqueous biomaterial ink into liquid building blocks with rigid shapes while preserving internal fluidity. The molded ink blocks for bone-like vertebrae and cartilaginous-intervertebral-disc shapes, are magnetically manipulated to assemble into hierarchical structures as a scaffold for subsequent spinal column tissue growth. It is also possible to join separate ink blocks by interfacial coalescence, different from bridging solid blocks by interfacial fixation. Generally, aqueous biomaterial inks are molded into shapes with high fidelity by the interfacial jamming of alginate surfactants. The molded liquid blocks can be reconfigured using induced magnetic dipoles, that dictated the magnetic assembly behavior of liquid blocks. The implanted spinal column tissue exhibits a biocompatibility based on in vitro seeding and in vivo cultivating results, showing potential physiological function such as bending of the spinal column.
              Cover page: Reconfigurable Magnetic Liquid Building Blocks for Constructing Artificial Spinal Column TissuesCreative Commons 'BY' version 4.0 license
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