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Open Access Publications from the University of California

Scholarly Works (21 results)

  • Thesis
  • Peer Reviewed
UCLA Electronic Theses and Dissertations (2014)

This dissertation consists of three essays on Applied Microeconomic Theory.

The first chapter studies investment incentives in a dynamic random search environment where a seller can make unobservable and selfish investments to reduce his production cost before searching for buyers. In the unique steady state equilibrium, although sellers make positive investments, equilibrium payoffs and the social welfare are a) constant given any search friction and b) equal to the values that would be created if there were no investment. These results hold even in the limit, with the investment strategy converges to the first best and the stationary investment distribution converges to a point mass at no investment.

The second chapter demonstrates how sorting conditions change in search frictions, in a dynamic random matching environment where heterogeneous buyers have private types and heterogeneous sellers make take-it-or-leave-it offers. We first establish the existence of

steady-state equilibrium and then characterize sorting conditions under two extreme

search frictions. Positive (negative) assortative matching requires the production function to be log-supermodular (log-submodular) with maximal search frictions. When search frictions vanish, the condition for

positive (negative) sorting returns to supermodularity (submodularity).

The last chapter examines how patents influence firms' allocation of resources over a portfolio of projects with different non-obviousness. We consider the situation where two identical firms have the replicas of two projects. One is known to be good and the other is risky but is more innovative conditional on being good. Compared to the allocation of resources without any patent, the total amount of resources allocated on the risky project is more efficient. However, the competition for the patent of the safe project also induces firms to inefficiently delay experimenting the risky project. Overall, the welfare effect of patents might be negative.

    Cover page: Three Essays on Applied Microeconomic Theory
    • Article
    • Peer Reviewed
    UC Irvine Previously Published Works (2018)
    In naked duplex DNA, G-C and A-T Watson-Crick base pairs exist in dynamic equilibrium with their Hoogsteen counterparts. Here, we used nuclear magnetic resonance (NMR) relaxation dispersion and molecular dynamics (MD) simulations to examine how Watson-Crick/Hoogsteen dynamics are modulated upon recognition of duplex DNA by the bisintercalator echinomycin and monointercalator actinomycin D. In both cases, DNA recognition results in the quenching of Hoogsteen dynamics at base pairs involved in intermolecular base-specific hydrogen bonds. In the case of echinomycin, the Hoogsteen population increased 10-fold for base pairs flanking the chromophore most likely due to intermolecular stacking interactions, whereas actinomycin D minimally affected Hoogsteen dynamics at other sites. Modulation of Hoogsteen dynamics at binding interfaces may be a general phenomenon with important implications for DNA-ligand and DNA-protein recognition.
      Cover page: Modulation of Hoogsteen dynamics on DNA recognition.
      • Article
      • Peer Reviewed
      UCLA Previously Published Works (2022)
      The recently emerging bismuth oxyhalide (BiOX) nanomaterials are promising indirect band gap photosensitizer for ultraviolet (UV) light-triggered phototherapy due to their unique layered nanosheet structure. However, the low absorption and poor photothermal conversion efficiency have always impeded their further applications in cancer clinical therapy. Herein, BiOCl rich in oxygen vacancies has been reported to have full-spectrum absorption properties, making it possible to achieve photothermal property under near-infrared laser. Under 808 nm irradiation, the photothermal conversion efficiency of black BiOCl nanosheets (BBNs) is up to 40%. BBNs@PEG can effectively clear primary subcutaneous tumors and prevent recurrence, achieving good synergistic treatment effect. These results not only broke the limitation of UV on the BiOCl material and provided a good template for other semiconductor materials, but also represent a promising approach to fabricate BBN@PEG a novel, potent and multifunctional theranostic platform for precise photothermal therapy and prognostic evaluation.
        Cover page: Controllable synthesis of layered black bismuth oxidechloride nanosheets and their applications in internal tumor ablation
        • Article
        • Peer Reviewed
        UC Davis Previously Published Works (2024)

        Background

        Intraoperative opioid use has a positive relationship with postoperative nausea and vomiting (PONV), and opioid-free anaesthesia (OFA) might reduce PONV. We investigated whether OFA compared with opioid-based anaesthesia would reduce PONV during the first 2 postoperative days among patients undergoing thoracoscopic lung resection.

        Methods

        In this randomised controlled trial, 120 adult patients were randomly assigned (1:1, stratified by sex) to receive either OFA with esketamine, dexmedetomidine, and sevoflurane, or opioid-based anaesthesia with sufentanil and sevoflurane. A surgical pleth index (SPI) of 20-50 was applied for intraoperative analgesia provision. All subjects received PONV prophylaxis (dexamethasone and ondansetron) and multimodal analgesia (flurbiprofen axetil, ropivacaine wound infiltration, and patient-controlled sufentanil). The primary outcome was the occurrence of PONV during the first 48 h after surgery.

        Results

        The median age was 53 yr and 66.7% were female. Compared with opioid-based anaesthesia, OFA significantly reduced the incidence of PONV (15% vs 31.7%; odds ratio [OR]=0.38, 95% confidence interval [CI], 0.16-0.91; number needed to treat, 6; P=0.031). Secondary and safety outcomes were comparable between groups, except that OFA led to a lower rate of vomiting (OR=0.23, 95% CI, 0.08-0.77) and a longer length of PACU stay (median difference=15.5 min, 95% CI, 10-20 min). The effects of OFA on PONV did not differ in the prespecified subgroups of sex, smoking status, and PONV risk scores.

        Conclusions

        In the context of PONV prophylaxis and multimodal analgesia, SPI-guided opioid-free anaesthesia halved the incidence of PONV after thoracoscopic lung resection, although it was associated with a longer stay in the PACU.

        Clinical trial registration

        Chinese Clinical Trial Registry (ChiCTR2200059710).
          Cover page: Opioid-free anaesthesia reduces postoperative nausea and vomiting after thoracoscopic lung resection: a randomised controlled trialCreative Commons 'BY' version 4.0 license
          • Article
          • Peer Reviewed
          UC Berkeley Previously Published Works (2021)
          Heterometallic clusters have attracted broad interests in the synthetic chemistry due to their various coordination modes and potential applications in heterogeneous catalysis. Here we report the synthesis, experimental, and theoretical characterizations of four ternary clusters ([M2(CO)6Sn2Sb5]3- (M = Cr, Mo), and [(MSn2Sb5)2]4-, (M = Cu, Ag)) in the process of capturing the hypho- [Sn2Sb5]3- in ethylenediamine (en) solution. We show that the coordination of the binary anion to transition-metal ions or fragments provides additional stabilization due to the formation of locally σ-aromatic units, producing a spherical aromatic shielding region in the cages. While in the case of [Mo2(CO)6Sn2Sb5]3- stabilization arises from locally σ-aromatic three-centre and five-centre two-electron bonds, aromatic islands in [(AgSn2Sb5)2]4- and [(CuSn2Sb5)2]4- render them globally antiaromatic. This work describes the coordination chemistry of the versatile building block [Sn2Sb5]3-, thus providing conceptual advances in the field of metal-metal bonding in clusters.
            Cover page: Ternary aromatic and anti-aromatic clusters derived from the hypho species [Sn2Sb5]3.
            • Article
            • Peer Reviewed
            UC Riverside Previously Published Works (2011)

            Background

            Exome sequencing, which allows the global analysis of protein coding sequences in the human genome, has become an effective and affordable approach to detecting causative genetic mutations in diseases. Currently, there are several commercial human exome capture platforms; however, the relative performances of these have not been characterized sufficiently to know which is best for a particular study.

            Results

            We comprehensively compared three platforms: NimbleGen's Sequence Capture Array and SeqCap EZ, and Agilent's SureSelect. We assessed their performance in a variety of ways, including number of genes covered and capture efficacy. Differences that may impact on the choice of platform were that Agilent SureSelect covered approximately 1,100 more genes, while NimbleGen provided better flanking sequence capture. Although all three platforms achieved similar capture specificity of targeted regions, the NimbleGen platforms showed better uniformity of coverage and greater genotype sensitivity at 30- to 100-fold sequencing depth. All three platforms showed similar power in exome SNP calling, including medically relevant SNPs. Compared with genotyping and whole-genome sequencing data, the three platforms achieved a similar accuracy of genotype assignment and SNP detection. Importantly, all three platforms showed similar levels of reproducibility, GC bias and reference allele bias.

            Conclusions

            We demonstrate key differences between the three platforms, particularly advantages of solutions over array capture and the importance of a large gene target set.
              Cover page: Comprehensive comparison of three commercial human whole-exome capture platforms
              • Article
              • Peer Reviewed
              UC Davis Previously Published Works (2005)
              It has long been held as scientific fact that soon after birth, cardiomyocytes cease dividing, thus explaining the limited restoration of cardiac function after a heart attack. Recent demonstrations of cardiac myocyte differentiation observed in vitro or after in vivo transplantation of adult stem cells from blood, fat, skeletal muscle, or heart have challenged this view. Analysis of these studies has been complicated by the large disparity in the magnitude of effects seen by different groups and obscured by the recently appreciated process of in vivo stem-cell fusion. We now show a novel population of nonsatellite cells in adult murine skeletal muscle that progress under standard primary cell-culture conditions to autonomously beating cardiomyocytes. Their differentiation into beating cardiomyocytes is characterized here by video microscopy, confocal-detected calcium transients, electron microscopy, immunofluorescent cardiac-specific markers, and single-cell patch recordings of cardiac action potentials. Within 2 d after tail-vein injection of these marked cells into a mouse model of acute infarction, the marked cells are visible in the heart. By 6 d they begin to differentiate without fusing to recipient cardiac cells. Three months later, the tagged cells are visible as striated heart muscle restricted to the region of the cardiac infarct.
                Cover page: Adult Murine Skeletal Muscle Contains Cells That Can Differentiate into Beating Cardiomyocytes In Vitro
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                UC Irvine Previously Published Works (2014)
                Regulatory T (Treg) cells are potent suppressors that maintain immune homeostasis. Accumulation of Treg can inhibit effective immune responses in cancer patients, leading to tumor development and progression. Despite direct cytotoxicity, several chemotherapeutic drugs have been reported to deplete Treg cells for better prognosis for cancer patients. Treg cells are a heterogenous population with at least three different subsets, nonsuppressive, resting, and activated Treg cells. However, the characteristics of Treg cell subsets in lung cancer patients and how chemotherapy affects Treg cells remain elusive. In this study, we first analyzed Treg cell subsets in peripheral blood samples from 40 nonsmall cell lung cancer (NSCLC) patients and 20 healthy donors. Treg cells, specifically activated Treg cell subset, significantly increased in patients with NSCLC. Compared to nonsuppressive Treg cells, activated Treg cells expressed higher level of CD39 and predominantly produced inhibitory cytokines. In vitro assay showed that docetaxel reduced all three subsets of Treg cells. More importantly, we found docetaxel-based chemotherapy significantly decreased all three Treg subsets after 4 cycles of treatment in 17 NSCLC patients. Taken together, this study revealed dynamic changes of various Treg cell subsets in NSCLC patients before and after chemotherapy, providing activated Treg cells as a potential target for chemotherapy.
                  Cover page: Selective depletion of regulatory T cell subsets by docetaxel treatment in patients with nonsmall cell lung cancer.Creative Commons 'BY' version 4.0 license
                  • Article
                  • Peer Reviewed
                  UC San Francisco Previously Published Works (2006)
                  Regulatory T (T reg) cells are critical regulators of immune tolerance. Most T reg cells are defined based on expression of CD4, CD25, and the transcription factor, FoxP3. However, these markers have proven problematic for uniquely defining this specialized T cell subset in humans. We found that the IL-7 receptor (CD127) is down-regulated on a subset of CD4(+) T cells in peripheral blood. We demonstrate that the majority of these cells are FoxP3(+), including those that express low levels or no CD25. A combination of CD4, CD25, and CD127 resulted in a highly purified population of T reg cells accounting for significantly more cells that previously identified based on other cell surface markers. These cells were highly suppressive in functional suppressor assays. In fact, cells separated based solely on CD4 and CD127 expression were anergic and, although representing at least three times the number of cells (including both CD25(+)CD4(+) and CD25(-)CD4(+) T cell subsets), were as suppressive as the "classic" CD4(+)CD25(hi) T reg cell subset. Finally, we show that CD127 can be used to quantitate T reg cell subsets in individuals with type 1 diabetes supporting the use of CD127 as a biomarker for human T reg cells.
                    Cover page: CD127 expression inversely correlates with FoxP3 and suppressive function of human CD4+ T reg cells
                    • Article
                    • Peer Reviewed
                    LBL Publications (2019)
                    When resources are limited, the hypocrealean fungus Trichoderma guizhouense can overgrow another hypocrealean fungus Fusarium oxysporum, cause sporadic cell death and arrest growth. A transcriptomic analysis of this interaction shows that T. guizhouense undergoes a succession of metabolic stresses while F. oxysporum responded relatively neutrally but used the constitutive expression of several toxin-encoding genes as a protective strategy. Because of these toxins, T. guizhouense cannot approach it is potential host on the substrate surface and attacks F. oxysporum from above. The success of T. guizhouense is secured by the excessive production of hydrogen peroxide (H2 O2 ), which is stored in microscopic bag-like guttation droplets hanging on the contacting hyphae. The deletion of NADPH oxidase nox1 and its regulator, nor1 in T. guizhouense led to a substantial decrease in H2 O2 formation with concomitant loss of antagonistic activity. We envision the role of NOX proteins in the antagonism of T. guizhouense as an example of metabolic exaptation evolved in this fungus because the primary function of these ancient proteins was probably not linked to interfungal relationships. In support of this, F. oxysporum showed almost no transcriptional response to T. guizhouense Δnox1 strain indicating the role of NOX/H2 O2 in signalling and fungal communication.
                      Cover page: Guttation capsules containing hydrogen peroxide: an evolutionarily conserved NADPH oxidase gains a role in wars between related fungi
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