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Open Access Publications from the University of California

Scholarly Works (32 results)

  • Article
  • Peer Reviewed
Proceedings of the Annual Meeting of the Cognitive Science Society, Volume 27 (2005)
    Cover page: Overshadowing as a Mechanism Underlying the Effect of Labels on Categorization
    • Article
    • Peer Reviewed
    Proceedings of the Annual Meeting of the Cognitive Science Society, Volume 33 (2011)
      Cover page: Using DSHM to Model Paper, Rock, Scissors
      • Thesis
      • Peer Reviewed
      UC Riverside Electronic Theses and Dissertations (2020)

      This dissertation presents three essays on agricultural productivity and its relationship with farm size and poverty. Chapter 1 addresses the relationship between farm size and productivity, a recurrent topic in development economics. We clarify the common productivity measures used in this literature, their relationships, and their advantages and limitations. Second, we argue that total factor productivity, not land productivity, is the appropriate indicator for most policy questions. Lastly, using a pseudo-panel of Brazilian farms spanning the period 1985-2006, we provide new evidence on the inverse relationship between farm size and productivity. The inverse relationship between size and land productivity is alive and well. The relationship between total factor productivity and size, in contrast, has evolved with modernization during this period. An inverse relationship between farm size and land productivity is neither necessary nor sufficient for an inverse relationship between farm size and total factor productivity.

      The hypothesis of a dynamic farm size – productivity relationship is extended to the context of Mexico in Chapter 2, identifying the relationship in a panel of family farms. We find a time invariant inverse relationship between farm size and both land productivity and total factor productivity. Stochastic frontier analysis reveals that, while technical change is expanding the frontier and technical inefficiency is growing for the entire sample, these changes are more pronounced for larger farms. An inverse relationship along the productivity frontier is disappearing in the wake of Mexico’s NAFTA-era reforms to agricultural policy, yet this change has not affected the farm size – total factor productivity relationship due to growing technical inefficiency.

      Chapter 3 conducts a counterfactual analysis of the contribution of changing land productivity to poverty alleviation on the farm. Stochastic frontier analysis enables a parametric decomposition of changes to the land productivity distribution in a panel of Mexican family farms. Using the decompositions, the contribution of productivity channels to poverty alleviation are estimated. The counterfactual analysis suggests that raising land productivity through intensification and technical change would be a more pro-poor approach than through increases in technical efficiency.

        Cover page: Essays on Agricultural Productivity, Poverty, and Farm Size
        • Article
        • Peer Reviewed
        Proceedings of the Annual Meeting of the Cognitive Science Society, Volume 30 (2008)
          Cover page: Modeling The Fan Effect Using Dynamically Structured Holographic Memory
          • Article
          • Peer Reviewed
          Proceedings of the Annual Meeting of the Cognitive Science Society, Volume 29 (2007)
            Cover page: MALTA: Enhancing ACT-R with a Holographic Persistent Knowledge Store
            • Article
            • Peer Reviewed
            Proceedings of the Annual Meeting of the Cognitive Science Society, Volume 34 (2012)
              Cover page: Cognitive Biases in a Geospatial Intelligence Analysis Task: An ACT-R Model
              • Article
              • Peer Reviewed
              UC San Francisco Previously Published Works (2020)
              Given the clinical effect of laminopathies, understanding lamin mechanical properties will benefit the treatment of heart failure. Here we report a mechano-dynamic study of LMNA mutations in neonatal rat ventricular myocytes (NRVM) using single cell spectroscopy with Atomic Force Microscopy (AFM) and measured changes in beating force, frequency and contractile amplitude of selected mutant-expressing cells within cell clusters. Furthermore, since beat-to-beat variations can provide clues on the origin of arrhythmias, we analyzed the beating rate variability using a time-domain method which provides a Poincaré plot. Data were further correlated to cell phenotypes. Immunofluorescence and calcium imaging analysis showed that mutant lamin changed NRVMs beating force and frequency. Additionally, we noted an altered microtubule network organization with shorter filament length, and defective hemichannel membrane localization (Connexin 43). These data highlight the interconnection between nucleoskeleton, cytoskeleton and sarcolemmal structures, and the transcellular consequences of mutant lamin protein in the pathogenesis of the cardiac laminopathies.
                Cover page: Altered microtubule structure, hemichannel localization and beating activity in cardiomyocytes expressing pathologic nuclear lamin A/C
                • Article
                • Peer Reviewed
                LBL Publications (2024)
                Some antihypertensive medications are photosensitizing. The implications for skin cancer risk remain unclear because results from prior studies are inconsistent and as new evidence is published. We performed a systematic review and meta-analysis to evaluate the association between antihypertensives and common skin cancers (cutaneous squamous cell carcinoma, basal cell carcinoma, and melanoma) and to evaluate dose-response relationships. Forty-four articles met inclusion criteria, and 42 could be meta analyzed. Increased risks were seen for basal cell carcinoma with calcium channel blockers (relative risk [RR] = 1.17, 95% confidence interval [CI] = 1.11-1.22), diuretics (RR = 1.06, 95% CI = 1.03-1.10), and thiazides (RR = 1.10, 95% CI = 1.04-1.16); for squamous cell carcinoma with calcium channel blockers (RR = 1.08, 95% CI = 1.01-1.14), diuretics (RR = 1.29, 95% CI = 1.17-1.43), and thiazides (RR = 1.36, 95% CI = 1.15-1.61); and for melanoma in angiotensin-converting enzyme inhibitors (RR = 1.09, 95% CI = 1.03-1.14), calcium channel blockers (RR = 1.08, 95% CI = 1.03-1.12), and thiazides (RR = 1.09, 95% CI = 1.02-1.17). The quality of evidence was low or very low. We observed evidence for dose-response for thiazides with basal cell carcinoma; angiotensin-converting enzyme inhibitors, diuretics, and thiazides with squamous cell carcinoma; and angiotensin-converting enzyme inhibitors, diuretics, and thiazides with melanoma. Our meta-analysis supports a potential causal association between some antihypertensives, particularly diuretics, and skin cancer risk.
                  Cover page: Antihypertensive Medications and Risk of Melanoma and Keratinocyte Carcinomas: A Systematic Review and Meta-Analysis.
                  • Article
                  • Peer Reviewed
                  UC San Francisco Previously Published Works (2018)

                  Aims

                  Given the clinical impact of LMNA cardiomyopathies, understanding lamin function will fulfill a clinical need and will lead to advancement in the treatment of heart failure. A multidisciplinary approach combining cell biology, atomic force microscopy (AFM), and molecular modeling was used to analyse the biomechanical properties of human lamin A/C gene (LMNA) mutations (E161K, D192G, N195K) using an in vitro neonatal rat ventricular myocyte model.

                  Methods and results

                  The severity of biomechanical defects due to the three LMNA mutations correlated with the severity of the clinical phenotype. AFM and molecular modeling identified distinctive biomechanical and structural changes, with increasing severity from E161K to N195K and D192G, respectively. Additionally, the biomechanical defects were rescued with a p38 MAPK inhibitor.

                  Conclusions

                  AFM and molecular modeling were able to quantify distinct biomechanical and structural defects in LMNA mutations E161K, D192G, and N195K and correlate the defects with clinical phenotypic severity. Improvements in cellular biomechanical phenotype was demonstrated and may represent a mechanism of action for p38 MAPK inhibition therapy that is now being used in human clinical trials to treat laminopathies.
                    Cover page: Biomechanical defects and rescue of cardiomyocytes expressing pathologic nuclear lamins
                    • Article
                    • Peer Reviewed
                    UC San Francisco Previously Published Works (2015)
                    Atomic force microscopy (AFM) cell loading/unloading curves were used to provide comprehensive insights into biomechanical behavior of cardiomyocytes carrying the lamin A/C (LMNA) D192G mutation known to cause defective nuclear wall, myopathy and severe cardiomyopathy. Our results suggested that the LMNA D192G mutation increased maximum nuclear deformation load, nuclear stiffness and fragility as compared to controls. Furthermore, there seems to be a connection between this lamin nuclear mutation and cell adhesion behavior since LMNA D192G cardiomyocytes displayed loss of AFM probe-to-cell membrane adhesion. We believe that this loss of adhesion involves the cytoskeletal architecture since our microscopic analyses highlighted that mutant LMNA may also lead to a morphological alteration in the cytoskeleton. Furthermore, chemical disruption of the actin cytoskeleton by cytochalasin D in control cardiomyocytes mirrored the alterations in the mechanical properties seen in mutant cells, suggesting a defect in the connection between the nucleoskeleton, cytoskeleton and cell adhesion molecules in cells expressing the mutant protein. These data add to our understanding of potential mechanisms responsible for this fatal cardiomyopathy, and show that the biomechanical effects of mutant lamin extend beyond nuclear mechanics to include interference of whole-cell biomechanical properties.
                      Cover page: The Cardiomyopathy Lamin A/C D192G Mutation Disrupts Whole-Cell Biomechanics in Cardiomyocytes as Measured by Atomic Force Microscopy Loading-Unloading Curve Analysis
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