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Open Access Publications from the University of California

Scholarly Works (10 results)

  • Thesis
  • Peer Reviewed
UC Santa Cruz Electronic Theses and Dissertations (2015)

The middle Eocene is a transitional period from the greenhouse early Eocene to the ice-house Eocene-Oligocene Transition. Due to lack of high-resolution records, the details of this long-term cooling trend are not clear. Low-resolution atmospheric CO2 records suggest declining, but highly variable levels during the middle Eocene which might have driven transient climate variations. However, high-resolution stable isotope records are lacking to document the true climate patterns over this period. Moreover, orbital scale climate reconstructions are essential for reconciling how the sensitivity to orbital forcing changed, if at all, as the greenhouse boundary conditions changes from the early to late Eocene. High-resolution isotope and trace metal records are also essential for constraining the evolution of northern hemispheric sea-ice and continental glaciation as well as North Atlantic Deep Water in the middle Eocene.

To address these shortcomings, I have generated high-resolution stable isotope and trace element data for a site in the northern Atlantic on Newfoundland Ridge (IODP, Site 1408). The records span Chron20r (46.4~43.8 Ma), and are the first orbital-scale stable isotope records for the early middle Eocene. With the exception of the uppermost portion of the section, the δ18O data indicate gradual cooling of 0.8~1.2 ⁰C/Myr over much of the section from 46.4Ma to 44.3 Ma which is consistent with the long-term global cooling trend. This is accompanied by a decrease in Mg/Ca records, while the paired δ18O-Mg/Ca analysis shows no pronounced shift in δ18Osw implying no variation in ice volume. In the upper part of the section (44.3~43.8 Ma), the δ18O shows a slight reversal consistent with warming, while Mg/Ca proxy indicates a continuous cooling. One hypothesis for the apparent between the two records is that the water mass reflects changes in the salinity of local bottom water and a possible shift toward a higher-latitude, cooler and less salty water source. In addition, clear astronomically paced cycles are observed in the stable isotopic and lithological records, and spectral analysis demonstrate that the cycles are dominated by 41-kyr obliquity cycles, a unique feature of Paleocene-Eocene records which are typically dominated by precession and eccentricity. This could reflect either shift in orbital configuration (low eccentricity signals or change in Earth’s tilt), or gradual climatic variation toward the ice-house world in the middle Eocene. Interbasin δ13C gradient reveals relatively low δ13C values at this northern Atlantic site compared with records from the Southern Ocean, indicating the meridional circulation was northward and/or North Atlantic Deep Water formation was absent or weak during this time.

    Cover page: Insight Into Climate Variations Of The Early Middle Eocene: High-Resolution Benthic Stable Isotope Data From Site 1408, Newfoundland Ridge
    • Thesis
    • Peer Reviewed
    UCLA Electronic Theses and Dissertations (2012)

    ABSTRACT OF THE DISSERTATION

    Linking Heroin Users in China to Drug Treatment

    and Other Resources in the Community:

    Effect of a Recovery Management Intervention Model

    by

    Fei Wu

    Doctor of Philosophy in Social Welfare

    University of California, Los Angeles, 2012

    Professor Robert Schilling, Chair

    Illicit drug use, especially injection heroin use, is a major contributor to the spread of HIV/AIDS and other infectious diseases in China. However, the traditional punitive approach toward drug abuse issues has been ineffective, signified by a high rate of relapse. In response, China has recently adopted a community recovery approach to reduce substance abuse, prevent infectious diseases, and assist drug user's reintegration into the society. This study investigates whether a recovery management intervention (RMI) can better link heroin users to drug treatment and other recovery related services in the community, improve their service utilization, and consequently generate positive recovery outcomes.

    This study conducted multivariate analysis using data of an intervention trial study entitled "Reducing HIV/AIDS and Drug Abuse among Heroin Addicts Released from Compulsory Rehabilitation in China". A latent variable modeling was utilized to test whether the RMI influences psychosocial factors (self-efficacy, self-esteem, social support, and barrier to treatment entry), predicts service utilization (drug treatment, social security, housing, employment, health etc.), which in turn predicts recovery outcomes (employment, drug use, and criminal activities).

    Results show that the RMI had no significant effect on drug users' psychosocial factors, and these factors were also not found to influence drug user's service utilization and recovery outcomes. Nevertheless, drug treatment enrollment and other social service utilization increased significantly among the RMI participants. In turn, increased service utilization led to more positive recovery outcomes in this group. The RMI also exerted direct effects on heroin users' community recovery through enhanced treatment and service utilization.

    Exploring effects of interventions like the RMI can shed light on how to make drug user's transition from the criminal justice system to the community effectively in China and other societies facing the same problem. Findings from this study suggest that better treatment enrollment, service utilization, and recovery outcomes can be potentially achieved with carefully designed case management interventions. More research effort needs to be placed in this field before introducing and implementing case management interventions on a larger scale in China.

      Cover page: Linking Heroin Users in China to Drug Treatment and Other Resources in the Community: Effect of a Recovery Management Intervention Model
      • Article
      • Peer Reviewed
      UC Merced Previously Published Works (2015)
      Fibronectin (Fn) forms a fibrillar network that controls cell behavior in both physiological and diseased conditions including cancer. Indeed, breast cancer-associated stromal cells not only increase the quantity of deposited Fn but also modify its conformation. However, (i) the interplay between mechanical and conformational properties of early tumor-associated Fn networks and (ii) its effect on tumor vascularization remain unclear. Here, we first used the Surface Forces Apparatus to reveal that 3T3-L1 preadipocytes exposed to tumor-secreted factors generate a stiffer Fn matrix relative to control cells. We then show that this early matrix stiffening correlates with increased molecular unfolding in Fn fibers, as determined by Förster Resonance Energy Transfer. Finally, we assessed the resulting changes in adhesion and proangiogenic factor (VEGF) secretion of newly seeded 3T3-L1s, and we examined altered integrin specificity as a potential mechanism of modified cell-matrix interactions through integrin blockers. Our data indicate that tumor-conditioned Fn decreases adhesion while enhancing VEGF secretion by preadipocytes, and that an integrin switch is responsible for such changes. Collectively, our findings suggest that simultaneous stiffening and unfolding of initially deposited tumor-conditioned Fn alters both adhesion and proangiogenic behavior of surrounding stromal cells, likely promoting vascularization and growth of the breast tumor. This work enhances our knowledge of cell - Fn matrix interactions that may be exploited for other biomaterials-based applications, including advanced tissue engineering approaches.
        Cover page: Stiffening and unfolding of early deposited-fibronectin increase proangiogenic factor secretion by breast cancer-associated stromal cells
        • Article
        • Peer Reviewed
        UCLA Previously Published Works (2016)
        Smartphone-based interventions are increasingly used to support self-monitoring, self-management, and treatment and medication compliance in order to improve overall functioning and well-being. In attempting to develop a smartphone application (S-Health) that assists heroin-dependent patients in recovery, a series of focus groups (72 patients, 22 providers) were conducted in China, Taiwan, and the USA to obtain their perspectives on its acceptance and potential adoption. Data were analyzed according to the Diffusion of Innovation (DOI) theory of characteristics important to the adoption of innovation. Important to Relative Advantage, USA participants cited S-Health's potential ability to overcome logistical barriers, while those in China and Taiwan valued its potential to supplement currently limited services. In terms of Compatibility, participants across sites reported recovery needs and goals that such an application could be helpful in supporting; however, its utility during strong craving was questioned in China and Taiwan. Important factors relevant to Complexity included concerns about smartphone access and familiarity, individualization of content, and particularly in China and Taiwan, participants wanted assurance of privacy and security. The study results suggest a general acceptance, but also indicate cultural variations in access to therapeutic and other social support systems, legal repercussions of substance use, societal perceptions of addiction, and the role of family and other social support in recovery. Taking these factors into consideration is likely to increase diffusion as well as effectiveness of these smartphone-based interventions.
          • Article
          • Peer Reviewed
          UC Santa Barbara Previously Published Works (2023)
          The transition from mafic to felsic upper continental crust (UCC) is crucial to habitability of Earth, and may be related to the onset of plate tectonics. Thus, defining when this crustal transition occurred has great significance for the evolution of Earth and its inhabitants. We demonstrate that V isotope ratios (reported as δ51V) provide insights into this transition because they correlate positively with SiO2 and negatively with MgO contents during igneous differentiation in both subduction zones and intraplate settings. Because δ51V is not affected by chemical weathering and fluid-rock interactions, δ51V of the fine-grained matrix of Archean to Paleozoic (3 to 0.3 Ga) glacial diamictite composites, which sample the UCC at the time of glaciation, reflect the chemical composition of the UCC through time. The δ51V values of glacial diamictites systematically increase with time, indicating a dominantly mafic UCC at ~3 Ga; the UCC was dominated by felsic rocks only after 3 Ga, coinciding with widespread continental emergence and many independent estimates for the onset of plate tectonics.
            Cover page: Dominance of felsic continental crust on Earth after 3 billion years ago is recorded by vanadium isotopes.
            • Article
            • Peer Reviewed
            UC Merced Previously Published Works (2015)
            Fibronectin (FN) is a glycoprotein found in the superficial zone of cartilage; however, its role in the lubrication and the wear protection of articular joints is unknown. In this work, we have investigated the molecular interactions between FN and various components of the synovial fluid such as lubricin (LUB), hyaluronan (HA), and serum albumin (SA), which are all believed to contribute to joint lubrication. Using a Surface Forces Apparatus, we have measured the normal (adhesion/repulsion) and lateral (friction) forces across layers of individual synovial fluid components physisorbed onto FN-coated mica substrates. Our chief findings are (i) FN strongly tethers LUB and HA to mica, as indicated by high and reversible long-range repulsive normal interactions between surfaces, and (ii) FN and LUB synergistically enhance wear protection of surfaces during shear, as suggested by the structural robustness of FN+LUB layers under pressures up to about 4 MPa. These findings provide new insights into the role of FN in the lubricating properties of synovial fluid components sheared between ideal substrates and represent a significant step forward in our understanding of cartilage damage involved in diseases such as osteoarthritis.
              Cover page: Fibronectin mediates enhanced wear protection of lubricin during shear
              • Article
              • Peer Reviewed
              UCLA Previously Published Works (2024)

              Background

              Substance use is a public crisis in the U.S. Substance use can be understood as a series of events in the life course, from initiation to mortality. Social Determinants of Health (SDoH) have increasingly been recognized as essential contributors to individuals' health. This scoping review aims to examine available evidence of SDoH impact on the life course of substance use disorder (SUD).

              Methods

              This study identified peer-reviewed articles that reported longitudinal studies with SDoH factors as independent variables and substance use and disorders as dependent variables from PubMed, Embase, and Web of Science. The reported associations between SDoH and substance use stages over the life course were narratively and graphically summarized.

              Results

              Among the 50 studies identified, ten revealed parental monitoring/support and early childhood education as protective factors, while negative peer influences and neighborhood instability were risk factors of substance use initiation. Nineteen articles reported factors associated with escalation in substance use, including unemployment, neighborhood vulnerability, negative peer influence, violence/trauma, and criminal justice system (CJS) involvement. Ten articles suggested that employment, social support, urban living, and low-barrier medication treatment facilitated treatment participation, while stigma and CJS involvement had negative impact on treatment trajectory. Social support and employment could foster progress in recovery and CJS involvement and unstable housing deterred recovery. Four studies suggested that unemployment, unstable housing, CJS involvement, and lack of social support were associated with overdose and mortality.

              Conclusions

              This review underscores the influence of social networks and early life experiences on the life course of SUD. Future SDoH research should investigate overdose and mortality and the impact of broader upstream SDoH on SUD. Interventions addressing these social factors are needed to mitigate their detrimental effects on the trajectories of SUD over the life course.
                Cover page: A scoping review of social determinants of health's impact on substance use disorders over the life course
                • Article
                • Peer Reviewed
                UC San Diego Previously Published Works (2015)
                Cancer-associated isocitrate dehydrogenase (IDH) 1 and 2 mutations gain a new activity of reducing α-KG to produce D-2-hydroxyglutarate (D-2-HG), which is proposed to function as an oncometabolite by inhibiting α-KG dependent dioxygenases. We investigated the function of D-2-HG in tumorigenesis using IDH1 and IDH2 mutant cancer cell lines. Inhibition of D-2-HG production either by specific deletion of the mutant IDH1-R132C allele or overexpression of D-2-hydroxyglutarate dehydrogenase (D2HGDH) increases α-KG and related metabolites, restores the activity of some α-KG-dependent dioxygenases, and selectively alters gene expression. Ablation of D-2-HG production has no significant effect on cell proliferation and migration, but strongly inhibits anchorage independent growth in vitro and tumor growth in xenografted mouse models. Our study identifies a new activity of oncometabolite D-2-HG in promoting tumorigenesis.
                  Cover page: D-2-hydroxyglutarate is essential for maintaining oncogenic property of mutant IDH-containing cancer cells but dispensable for cell growth
                  • Article
                  • Peer Reviewed
                  UCLA Previously Published Works (2014)

                  Objective

                  The aim of this study was to evaluate the risk factors associated with dropout from Methadone Maintenance Treatment (MMT) clinics within a 1 year follow-up cohort study in China.

                  Methods

                  A data analysis is to explore the adherence of MMT during one year from three hundred and twenty patients with heroin dependence at five clinics (3 in Shanghai, 2 in Kunming) in China. All participants were from the part of China-United States cooperation project entitled "Research about improving the compliance and efficacy of methadone maintenance treatment in China". Our data analysis includes the patients' attendance in the 6 months clinical study and the data in another 6 months afterward. The data of patients at baseline were collected with the Addiction Severity Index (ASI) which is a semi-structured questionnaire covering socio-demographic characteristics and drug use history. The one year attendance after recruitment at the clinics and daily dose were abstracted from the MMT clinic register system. The Cox proportional hazards model were used to explore the risk factor of dropout, defined as seven consecutive days without methadone.

                  Results

                  By the end of 1 year of treatment 86 patients still remained in MMT without dropout (87% in Shanghai and 13% patients in Kunming). Over the entire 1-year period the median days of remaining in the program were 84 days (in Shanghai and Kunming were 317 days and 22 days).The factors associated with retention included age (HR=0.98, 95%C.I.:0.96-0.99, P=0.0062) and ASI alcohol scores (HR=5.72, 95%C.I.:1.49-21.92, P=0.0109) at baseline.

                  Conclusion

                  One year retention of newly recruited patients with heroin dependence was related to age and ASI alcohol scores at baseline. The adherence is poorer for the patients who are young and having more serious alcohol problems.
                    Cover page: Factors associated with one year retention to methadone maintenance treatment program among patients with heroin dependence in China
                    • Article
                    • Peer Reviewed
                    UC Santa Cruz Previously Published Works (2023)
                      Cover page: North Atlantic Drift Sediments Constrain Eocene Tidal Dissipation and the Evolution of the EarthâMoon System
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