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Open Access Publications from the University of California

Scholarly Works (33 results)

  • Article
  • Peer Reviewed
Working Papers (2005)

Differential expansion and contraction between the top and bottom of a concrete slab results in curling. Curling affects stresses and deflections and is an important component of any mechanistic-empirical design procedure. A significant portion of curling can be attributed to the combined effects of nonlinear "built-in" temperature gradients, irreversible shrinkage, moisture gradients, and creep, which can be represented by an effective built-in temperature difference (EBITD).

Several instrumented test sections utilizing several design features were constructed and evaluated using the Heavy Vehicle Simulator (HVS) in Palmdale, California. These instrumented slabs were loaded with a half-axle edge load without wander in order to study the effects of curling and fail the slab sections under accelerated pavement testing. A procedure for estimating EBITD using loaded slab deflections was developed using the HVS results. The advantages of using loaded slab deflections are that they can be used for measuring EBITD of slabs with high negative built-in curl and can also be adapted for a Falling Weight Deflectometer, making the procedure efficient and cost-effective for the back-calculation of EBITD of in-service pavements. Differences in restraints and variability in concrete material properties resulted in EBITDs ranging from –5�C to greater than –30�C.

The HVS field tests were also used to examine Miner's hypothesis along with various fatigue damage models. Results indicate test slabs cracked at cumulative damage levels significantly different from unity. New models that incorporate stress range and loading rate along with peak stresses were developed. The coefficients for these models were developed to incorporate transverse cracking, longitudinal cracking, and corner breaks. The models can also be used for slabs that exhibit high negative EBITD. For slabs susceptible to high shrinkage gradients, microcracking resulting from restraint stresses during early ages can significantly reduce the slab's nominal strength. Early-age restraint can vary considerably from one slab to another, depending on restraint. A procedure to model slab strength reduction and slab size was developed using nonlinear fracture mechanics principles. A parameter called the "effective initial crack depth" is introduced to characterize the early-age surface microcracking.

    Cover page: Characterization of Effective Built-in Curling and Concrete Pavement Cracking on the Palmdale Test Sections
    • Article
    Research Reports (2000)
    The California Department of Transportation (Caltrans) Long-Life Pavement Rehabilitation Strategies (LLPRS) Task Force was commissioned in April 1997. The product that Caltrans has identified for the LLPRS Task Force to develop is Draft Long Life Pavement Rehabilitation guidelines and specifications for implementation on projects in the 1998/99 fiscal year. The focus of the LLPRS Task Force has been rigid pavement strategies. A separate task force has more recently been established for flexible pavement strategies, called the Asphalt Concrete Long-Life (AC Long-Life) Task Force. The University of California at Berkeley (UCB) and its subcontractors, Dynatest, Inc., the Roads and Transport Technology Division of the Council for Scientific and Industrial Research (CSIR), and Symplectic Engineering Corporation, Inc. are investigating for Caltrans the viability of various LLPRS optional strategies that have been proposed.
      Cover page: Investigation of Design and Construction Issues for Long Life Concrete Pavement Strategies
      • Article
      Research Reports (2000)

      This report details the fast-setting hydraulic cement concrete (FSHCC) field construction. instrumentation, and strength testing of the field heavy vehicle simulator (HVS) test site on State Route 14 near Palmdale, California, which took place from June 5-18, 1998. This research was conducted as part of the California Accelerated Pavement Testing Program (CAL/APT) to look at the Caltrans proposed long-life pavement rehabilitation strategies (LLPRS). The project work included installation of internal (embedded in the pavement) and external pavement instrumentation, construction material sampling and testing, full-scale accelerated pavement testing on the field-constructed FSHCC pavements using Caltrans Heavy Vehicle Simulator No. 2 (HVS2), and monitoring of the loaded and unloaded test sections with respect to dynamic and environmental loading. The project work also included a laboratory component to validate the field HVS results, as well as computer modeling and analysis. 

       

        Cover page: Construction, Instrumentation, and Testing of Fast-Setting Hydraulic Cement Concrete in Palmdale, California
        • Article
        • Peer Reviewed
        UC Davis Previously Published Works (2015)
        In this study, we present a new modeling framework and a large ensemble of climate projections to investigate the uncertainty in regional climate change over the United States (US) associated with four dimensions of uncertainty. The sources of uncertainty considered in this framework are the emissions projections, global climate system parameters, natural variability and model structural uncertainty. The modeling framework revolves around the Massachusetts Institute of Technology (MIT) Integrated Global System Model (IGSM), an integrated assessment model with an Earth System Model of Intermediate Complexity (EMIC) (with a two-dimensional zonal-mean atmosphere). Regional climate change over the US is obtained through a two-pronged approach. First, we use the IGSM-CAM framework, which links the IGSM to the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM). Second, we use a pattern-scaling method that extends the IGSM zonal mean based on climate change patterns from various climate models. Results show that the range of annual mean temperature changes are mainly driven by policy choices and the range of climate sensitivity considered. Meanwhile, the four sources of uncertainty contribute more equally to end-of-century precipitation changes, with natural variability dominating until 2050. For the set of scenarios used in this study, the choice of policy is the largest driver of uncertainty, defined as the range of warming and changes in precipitation, in future projections of climate change over the US.
          Cover page: A framework for modeling uncertainty in regional climate changeCreative Commons 'BY' version 4.0 license
          • Article
          Research Reports (1999)
          Over the past 50 years, only several full-scale concrete pavements have been tested, e.g., the AASHO Road Test, Mn/ROAD, and the various US Army Corps of Engineers tests (1). These full-scale test pavements have resulted in essential information for further improvement in pavement design procedures. They have also raised many questions that need to be answered with future road tests. The use of accelerated pavement testing equipment enables full-scale concrete pavements to be constructed and tested more cheaply than road tests. Caltrans currently owns two heavy vehicle simulators (HVS), which have been used to load asphalt concrete pavements at the University of California at Berkeley. The HVS allows for continuous load testing in a controlled environment and the potential for reduced variability in materials and testing. In order to evaluate the future performance of rehabilitated concrete pavements, the second HVS was used to test an accelerated Portland Cement Concrete pavement section constructed at the University of California-Berkeley. The main goals of this accelerated pavement testing was to familiarize the staff with concrete pavement construction, install instrumentation in the slabs, develop a rigid pavement testing procedure using the HVS, and monitor the in-situ instrumentation with loading. All the information and experience gained from this testing would be needed later for instrumentation and HVS testing of six fast setting hydraulic cement concrete (FSHCC) test sections located in Palmdale, CA.
            Cover page: CAL/APT Goal LLPRS--Rigid Phase III: Concrete Test Section 516CT Report
            • Article
            • Peer Reviewed
            UC San Diego Previously Published Works (2008)

            Background

            With the sequence of the Plasmodium falciparum genome and several global mRNA and protein life cycle expression profiling projects now completed, elucidating the underlying networks of transcriptional control important for the progression of the parasite life cycle is highly pertinent to the development of new anti-malarials. To date, relatively little is known regarding the specific mechanisms the parasite employs to regulate gene expression at the mRNA level, with studies of the P. falciparum genome sequence having revealed few cis-regulatory elements and associated transcription factors. Although it is possible the parasite may evoke mechanisms of transcriptional control drastically different from those used by other eukaryotic organisms, the extreme AT-rich nature of P. falciparum intergenic regions (approximately 90% AT) presents significant challenges to in silico cis-regulatory element discovery.

            Results

            We have developed an algorithm called Gene Enrichment Motif Searching (GEMS) that uses a hypergeometric-based scoring function and a position-weight matrix optimization routine to identify with high-confidence regulatory elements in the nucleotide-biased and repeat sequence-rich P. falciparum genome. When applied to promoter regions of genes contained within 21 co-expression gene clusters generated from P. falciparum life cycle microarray data using the semi-supervised clustering algorithm Ontology-based Pattern Identification, GEMS identified 34 putative cis-regulatory elements associated with a variety of parasite processes including sexual development, cell invasion, antigenic variation and protein biosynthesis. Among these candidates were novel motifs, as well as many of the elements for which biological experimental evidence already exists in the Plasmodium literature. To provide evidence for the biological relevance of a cell invasion-related element predicted by GEMS, reporter gene and electrophoretic mobility shift assays were conducted.

            Conclusion

            This GEMS analysis demonstrates that in silico regulatory element discovery can be successfully applied to challenging repeat-sequence-rich, base-biased genomes such as that of P. falciparum. The fact that regulatory elements were predicted from a diverse range of functional gene clusters supports the hypothesis that cis-regulatory elements play a role in the transcriptional control of many P. falciparum biological processes. The putative regulatory elements described represent promising candidates for future biological investigation into the underlying transcriptional control mechanisms of gene regulation in malaria parasites.
              Cover page: In silico discovery of transcription regulatory elements in Plasmodium falciparum
              • Article
              • Peer Reviewed
              UCLA Previously Published Works (2018)
              Myeloid malignancies, including myelodysplastic syndromes, chronic myelomonocytic leukemia, and acute myeloid leukemia, are characterized by abnormal proliferation and differentiation of hematopoietic stem and progenitor cells (HSPCs). Reports on analysis of bone marrow samples from patients have revealed a high incidence of mutations in splicing factors in early stem and progenitor cell clones, but the mechanisms underlying transformation of HSPCs harboring these mutations remain unknown. Using ex vivo cultures of primary human CD34+ cells as a model, we find that mutations in splicing factors SRSF2 and U2AF1 exert distinct effects on proliferation and differentiation of HSPCs. SRSF2 mutations cause a dramatic inhibition of proliferation via a G2-M phase arrest and induction of apoptosis. U2AF1 mutations, conversely, do not significantly affect proliferation. Mutations in both SRSF2 and U2AF1 cause abnormal differentiation by skewing granulo-monocytic differentiation toward monocytes but elicit diverse effects on megakaryo-erythroid differentiation. The SRSF2 mutations skew differentiation toward megakaryocytes whereas U2AF1 mutations cause an increase in the erythroid cell populations. These distinct functional consequences indicate that SRSF2 and U2AF1 mutations have cell context-specific effects and that the generation of myeloid disease phenotype by mutations in the genes coding these two proteins likely involves different intracellular mechanisms. Stem Cells 2018;36:1663-1675.
                Cover page: Myeloid Disease Mutations of Splicing Factor SRSF2 Cause G2-M Arrest and Skewed Differentiation of Human Hematopoietic Stem and Progenitor Cells
                • Article
                • Peer Reviewed
                UCLA Previously Published Works (2013)

                Purpose

                To explore the use of approximate entropy (ApEn) as an index of the complexity and the synchronicity of resting state blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in normal aging and cognitive decline associated with familial Alzheimer's disease (fAD).

                Materials and methods

                Resting state BOLD fMRI data were acquired at 3T from two independent cohorts of subjects consisting of healthy young (age 23 ± 2 years, n = 8) and aged volunteers (age 66 ± 3 years, n = 8), as well as 22 fAD associated subjects (14 mutation carriers, age 41.2 ± 15.8 years; and eight nonmutation carrying family members, age 28.8 ± 5.9 years). Mean ApEn values were compared between the two age groups and correlated with cognitive performance in the fAD group. Cross-ApEn (C-ApEn) was further calculated to assess the asynchrony between precuneus and the rest of the brain.

                Results

                Complexity of brain activity measured by mean ApEn in gray and white matter decreased with normal aging. In the fAD group, cognitive impairment was associated with decreased mean ApEn in gray matter as well as decreased regional ApEn in right precuneus, right lateral parietal regions, left precentral gyrus, and right paracentral gyrus. A pattern of asynchrony between BOLD fMRI series emerged from C-ApEn analysis, with significant regional anti-correlation with cross-correlation coefficient of functional connectivity analysis.

                Conclusion

                ApEn and C-ApEn may be useful for assessing the complexity and synchronicity of brain activity in normal aging and cognitive decline associated with neurodegenerative diseases.
                  Cover page: Complexity and synchronicity of resting state blood oxygenation level‐dependent (BOLD) functional MRI in normal aging and cognitive decline
                  • Article
                  • Peer Reviewed
                  UC Irvine Previously Published Works (2008)
                    Cover page: The collaboration readiness of transdisciplinary research teams and centers: Findings from the National Cancer Institute TREC Year-One Evaluation StudyCreative Commons 'BY' version 4.0 license
                    • Article
                    • Peer Reviewed
                    UC Davis Previously Published Works (2023)
                    Macrophages employ an array of pattern recognition receptors to detect and eliminate intracellular pathogens that access the cytosol. The cytosolic carbohydrate sensors Galectin-3, -8, and -9 (Gal-3, Gal-8, and Gal-9) recognize damaged pathogen-containing phagosomes, and Gal-3 and Gal-8 are reported to restrict bacterial growth via autophagy in cultured cells. However, the contribution of these galectins to host resistance during bacterial infection in vivo remains unclear. We found that Gal-9 binds directly to Mycobacterium tuberculosis (Mtb) and Salmonella enterica serovar Typhimurium (Stm) and localizes to Mtb in macrophages. To determine the combined contribution of membrane damage-sensing galectins to immunity, we generated Gal-3, -8, and -9 triple knockout (TKO) mice. Mtb infection of primary macrophages from TKO mice resulted in defective autophagic flux but normal bacterial replication. Surprisingly, these mice had no discernable defect in resistance to acute infection with Mtb, Stm or Listeria monocytogenes, and had only modest impairments in bacterial growth restriction and CD4 T cell activation during chronic Mtb infection. Collectively, these findings indicate that while Gal-3, -8, and -9 respond to an array of intracellular pathogens, together these membrane damage-sensing galectins play a limited role in host resistance to bacterial infection.
                      Cover page: Deficiency in Galectin-3, -8, and -9 impairs immunity to chronic Mycobacterium tuberculosis infection but not acute infection with multiple intracellular pathogens
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