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Open Access Publications from the University of California

Scholarly Works (28 results)

  • Thesis
  • Peer Reviewed
UC Berkeley Electronic Theses and Dissertations (2012)

This dissertation is comprised of two chapters, each of which contributes to the field of financial economics, particularly in the areas of behavioral and household finance.

"Corporate News, Asset Prices, and the Media" examines investor reaction to stale information using a novel data set containing a time-stamped transcript of the financial news network CNBC. I measure changes in stock price and trading volume at the precise time that a company is mentioned on CNBC in the 24 hours following a corporate news event, and find strong evidence that some investors react to stale news. There is a significant increase in stock price at the precise time that a company is mentioned on CNBC following a positive news event. Surprisingly, there is also a significant increase in stock price at the precise time that a company is mentioned on CNBC following a negative news event. This puzzle is not explained using observable differences between positive and negative news events or their subsequent mentions. Evidence using cross-sectional variation in the number of positive and negative words suggests that media attention can inflate asset prices in the presence of short-sale constraints as investors with the most optimistic valuations are able to buy while those with the most pessimistic valuations are unable to sell short.

"Outstanding Debt and the Household Portfolio," co-authored with my classmate Thomas A. Becker, alters a simple portfolio choice model to allow households to retire outstanding debt and realize a risk-free rate of return equal to the interest rate on that debt. Using the Survey of Consumer Finances we find that households with mortgage debt are 10 percent less likely to own stocks and 37 percent less likely to own bonds compared to similar households with no outstanding mortgage debt. To show that our results are not driven by irrational behavior amongst a subset of households, we construct two proxy variables for financial naivete. Finally we calculate the costs of non-optimal investment decisions in the presence of various forms of household debt including mortgages, home equity loans and credit card debt. We find that 26 percent of households should forego equity market participation on account of the high interest rates that they pay on their debt.

    Cover page: Essays in Financial Economics
    • Thesis
    • Peer Reviewed
    UCLA Electronic Theses and Dissertations (2020)

    In the western United States and in many arid regions, wastewater reclamation is

    becoming a common way of increasing water supplies. More and more wastewater

    is being reclaimed for non-potable uses such as irrigation, but indeed reclamation

    for potable use is also being practiced. One of the concerns for wastewater

    reclamation are the contaminants that are not removed by either the wastewater or

    water treatment processes and this is especially for the case of case of potable

    reclamation. Radionuclides are rarely a concern in wastewater treatment and

    reclamation systems, but the recent accident at Fukushima has focused attention on

    the spread of fission and decay byproduct across farmlands and into drinking water

    systems.

    iii

    In addition, recent wildfires in the abundant territory around Chernobyl caused

    release of long-lived fission products to the atmosphere that had previously been

    sequestered in the terrestrial system. At this time there is only anecdotal data

    available on the impact of the fires on the wastewater radioactivity but it is a

    continuing issue.

    An important concern is the fate of radionuclides during wastewater reclamation. In

    former times, it was assumed that reclamation activities will stop if there is a

    contamination problem, but with increasing reliance on reclamation, stopping it may

    have important and perhaps severe effects, including the loss of key industries that

    use reclaimed water such as petroleum refining. More importantly major cities,

    including Los Angeles, have aggressive programs for recycling 100% of its

    wastewater to become a main part of its water portfolio. Therefore, in the future any

    unexpected interruption in the reclamation programs will have major impacts.

    In this dissertation previous observations of the radionuclides in wastewater

    treatment plants are reviewed and summarized. As part of this research, a variety of

    wastewater sludge samples were analyzed for radionuclides and results are presented

    and fate and transport of two radionuclides, 131I and 40K are discussed in detail.

      Cover page: Fate of Radionuclides in Wastewater Treatment Plants
      • Article
      • Peer Reviewed
      UC Berkeley Previously Published Works (2014)
      Continuous quantum measurement is the backbone of various methods in quantum control, quantum metrology, and quantum information. Here, we present a generalized formulation of dispersive measurement of a complex quantum systems. We describe the complex system as an open quantum system that is strongly coupled to a non-Markovian environment, enabling the treatment of a broad variety of natural or engineered complex systems. The system is monitored via a probe resonator coupled to a broadband (Markovian) reservoir. Based on this model, we derive a formalism of stochastic hierarchy equations of motion describing the decoherence dynamics of the system conditioned on the measurement record. Furthermore, we demonstrate a spectroscopy method based on weak quantum measurement to reveal the non-Markovian nature of the environment, which we term weak spectroscopy.
        Cover page: Continuous Measurement of a Non-Markovian Open Quantum System
        • Thesis
        • Peer Reviewed
        UCLA Electronic Theses and Dissertations (2013)

        In the western United States and in many arid regions, wastewater reclamation is becoming a common way of increasing water supplies. More and more wastewater is being reclaimed for non-potable uses such as irrigation, but reclamation for potable use is also being practiced. One of the concerns for wastewater reclamation is the distribution of contaminants that are not removed by either the wastewater treatment plant or the water treatment plant in the case of potable reclamation. The recent accident at Fukushima has focused attention on the spread of fission and decay byproduct across farmlands and into drinking water systems. An important concern is the distribution of radionuclides by wastewater reclamation. In former times, it was assumed that

        reclamation activities will stop if there is a contamination problem, but with increasing

          ii

        reliance of reclamation, stopping reclamation may have important and perhaps severe effects, including the loss of key industries such as petroleum refining that use reclaimed water. This thesis is a review of the important radionuclides that may be produced from a fission accident or a spill, and their fate in a wastewater treatment plant. Since experimental approaches for studying this problem are not generally feasible, a review of all the documented occurrences of spills has been made. In some cases the fate of fallout from atmospheric testing has been observed and this also provides useful information. The overall goal is to develop the knowledge that will allow treatment plant operators to react quickly to an accident or spill and provide guidance for temporary or short term measures to mitigate the impacts.

          Cover page: Fate of Radionuclides in Wastewater Treatment Plants
          • Article
          • Peer Reviewed
          UC San Francisco Previously Published Works (2023)
          Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a single-stranded RNA virus and a member of the corona virus family, primarily affecting the upper respiratory system and the lungs. Like many other respiratory viruses, SARS-CoV-2 can spread to other organ systems. Apart from causing diarrhea, another very common but debilitating complication caused by SARS-CoV-2 is neurological symptoms and cognitive difficulties, which occur in up to two thirds of hospitalized COVID-19 patients and range from shortness of concentration and overall declined cognitive speed to executive or memory function impairment. Neuro-cognitive dysfunction and brain fog are frequently present in COVID-19 cases, which can last several months after the infection, leading to disruption of daily life. Cumulative evidence suggests that SARS-CoV-2 affects vasculature in the extra-pulmonary systems directly or indirectly, leading to impairment of endothelial function and even multi-organ damage. The post COVID-19 long-lasting neurocognitive impairments have not been studied fully and their underlying mechanism remains elusive. In this review, we summarize the current understanding of the effects of COVID-19 on vascular dysfunction and how vascular dysfunction leads to cognitive impairment in patients.
            Cover page: Vascular Dysfunctions Contribute to the Long-Term Cognitive Deficits Following COVID-19.Creative Commons 'BY' version 4.0 license
            • Article
            • Peer Reviewed
            UC San Francisco Previously Published Works (2016)

            Background and objectives

            Family medicine postgraduate programmes in Kenya are examining the benefits of Community-Oriented Primary Care (COPC) curriculum, as a method to train residents in population-based approaches to health care delivery. Whilst COPC is an established part of family medicine training in the United States, little is known about its application in Kenya. We sought to conduct a qualitative study to explore the development and implementation of COPC curriculum in the first two family medicine postgraduate programmes in Kenya.

            Method

            Semi-structured interviews of COPC educators, practitioners, and academic stakeholders and focus groups of postgraduate students were conducted with COPC educators, practitioners and academic stakeholders in two family medicine postgraduate programmes in Kenya. Discussions were transcribed, inductively coded and thematically analysed.

            Results

            Two focus groups with eight family medicine postgraduate students and interviews with five faculty members at two universities were conducted. Two broad themes emerged from the analysis: expected learning outcomes and important community-based enablers. Three learning outcomes were (1) making a community diagnosis, (2) understanding social determinants of health and (3) training in participatory research. Three community-based enablers for sustainability of COPC were (1) partnerships with community health workers, (2) community empowerment and engagement and (3) institutional financial support.

            Conclusions

            Our findings illustrate the expected learning outcomes and important communitybased enablers associated with the successful implementation of COPC projects in Kenya and will help to inform future curriculum development in Kenya.
              Cover page: An assessment of implementation of Community-Oriented Primary Care in Kenyan family medicine postgraduate medical education programmesCreative Commons 'BY' version 4.0 license
              • Article
              • Peer Reviewed
              UC San Francisco Previously Published Works (2022)
              It can be difficult to avoid violating the pleura during the retropleural approach to the thoracolumbar spine. In this video, the authors resect a short segment of rib to allow more room for pleural dissection during a minimally invasive (MIS) lateral retropleural approach. After a lateral MIS skin incision, the rib is dissected and removed, clearly identifying the retropleural space. The curvature of the rib can then be followed, decreasing the risk of pleural violation. The pleura can then be mobilized ventrally until the spine is accessed. Managing the diaphragm is also illustrated by separating the fibers without a traditional cut through the muscle. The video can be found here: https://stream.cadmore.media/r10.3171/2022.3.FOCVID21138.
                Cover page: Short segment rib resection to mitigate risk of pleural violation during retropleural lateral thoracic interbody fusion.
                • Article
                • Peer Reviewed
                UC San Francisco Previously Published Works (2024)
                Endoglin (ENG) mutation causes type 1 hereditary hemorrhagic telangiectasia (HHT1). HHT1 patients have arteriovenous malformations (AVMs) in multiple organs, including the brain. In mice, Eng deletion induced by R26RCreER or SM22αCre leads to AVM development in the brain and other organs. We hypothesized that an increase in Eng- negative ECs will enhance AVM severity. To increase EC Eng deletion, we used a codon-improved cre (icre), which is more potent in recombination of the floxed alleles than the wild-type (WT) cre. R26RCreER;Engf/f mice that have a Rosa promoter driving and tamoxifen (TM)-inducible WT cre expression globally, and PdgfbiCreER;Engf/f mice that have a Pdgfb promoter driving and TM-inducible icre expression in ECs were treated with three intra-peritoneal injections of TM (2.5 mg/25 g of body weight) to delete Eng globally or in the ECs. AAV-VEGF was stereotactically injected into the brain to induce brain focal angiogenesis and brain AVM. We found that icre caused more Eng deletion in the brain, indicated by a lower level of Eng proteins (p < 0.001) and fewer Eng-positive ECs (p = 0.01) than mice with WT cre. Mice with icre-mediated Eng deletion have more abnormal vessels (p = 0.02), CD68+ macrophages (p = 0.002), and hemorrhage (p = 0.04) and less vascular pericyte and smooth muscle coverage than mice with WT cre. In addition, arteriovenous shunts were detected in the intestines of icre mice, a phenotype that has not been detected in WT cre mice before. RNA-seq analysis showed that 8 out of the 10 top upregulated pathways identified by gene ontology (GO) analysis are related to inflammation. Therefore, the increase in Eng deletion in ECs exacerbates AVM severity, which is associated with enhanced inflammation. Strategies that can reduce Eng-negative ECs could be used to develop new therapies to reduce AVM severity for HHT1 patients.
                  Cover page: Increasing Endoglin Deletion in Endothelial Cells Exacerbates the Severity of Brain Arteriovenous Malformation in Mouse.Creative Commons 'BY' version 4.0 license
                  • Article
                  • Peer Reviewed
                  UC Irvine Previously Published Works (2023)
                  Plasmodium ookinetes use an invasive apparatus to invade mosquito midguts, and tubulins are the major structural proteins of this apical complex. We examined the role of tubulins in malaria transmission to mosquitoes. Our results demonstrate that the rabbit polyclonal antibodies (pAb) against human α-tubulin significantly reduced the number of P. falciparum oocysts in Anopheles gambiae midguts, while rabbit pAb against human β-tubulin did not. Further studies showed that pAb, specifically against P. falciparum α-tubulin-1, also significantly limited P. falciparum transmission to mosquitoes. We also generated mouse monoclonal antibodies (mAb) using recombinant P. falciparum α-tubulin-1. Out of 16 mAb, two mAb, A3 and A16, blocked P. falciparum transmission with EC50 of 12 μg/ml and 2.8 μg/ml. The epitopes of A3 and A16 were determined to be a conformational and linear sequence of EAREDLAALEKDYEE, respectively. To understand the mechanism of the antibody-blocking activity, we studied the accessibility of live ookinete α-tubulin-1 to antibodies and its interaction with mosquito midgut proteins. Immunofluorescent assays showed that pAb could bind to the apical complex of live ookinetes. Moreover, both ELISA and pull-down assays demonstrated that insect cell-expressed mosquito midgut protein, fibrinogen-related protein 1 (FREP1), interacts with P. falciparum α-tubulin-1. Since ookinete invasion is directional, we conclude that the interaction between Anopheles FREP1 protein and Plasmodium α-tubulin-1 anchors and orients the ookinete invasive apparatus towards the midgut PM and promotes the efficient parasite infection in the mosquito.
                    Cover page: Targeting plasmodium α-tubulin-1 to block malaria transmission to mosquitoesCreative Commons 'BY' version 4.0 license
                    • Article
                    UC San Francisco Previously Published Works (2023)

                    Background:

                    Increase of collagen I (COL I)/COL III ratio enhances vessel wall stiffness and renders vessels less resistant to blood flow and pressure changes. We hypothesized that COL I/COL III ratio is increased in the brain arteriovenous malformations (bAVMs), which is associated with bAVM hemorrhage.

                    Method:

                    Surgically resected human bAVM samples and mouse bAVMs induced in three transgenic mouse lines with activin receptor-like kinase 1 or endoglin deletion in the endothelial cells or in the brain focally. Colony-stimulating factor receptor inhibitor was used to transiently deplete microglia. COL I and COL III levels, hemorrhage, and gene expression in bAVMs were analyzed.

                    Results:

                    The COL I and COL III levels and the COL I/COL III ratio were higher on human and mouse bAVMs than controls, which was associated with bAVM hemorrhage. Col I and Col III mRNAs were also increased in mouse bAVMs. The degree of microhemorrhage in mouse bAVMs was positively correlated with Col I/Col III ratios. Transient depletion of microglia reduced Col I/Col III ratio and microhemorrhage in mouse bAVMs.

                    Conclusion:

                    COL I/COL III ratio are increased in bAVM vessels, which is associated with bAVM hemorrhage. Depletion of microglia reduces Col I/Col III ratio and hemorrhage in mice bAVMs.
                      Cover page: Increased Collagen I/ Collagen III Ratio Is Associated with Hemorrhage in Brain Arteriovenous Malformations in Human and Mouse
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