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Open Access Publications from the University of California

Scholarly Works (30 results)

  • Thesis
  • Peer Reviewed
UC Merced Electronic Theses and Dissertations (2009)

This research examined the in-stream sediment sources for four 1 km2 headwater catchments in the central Sierra Nevada, California. Erosion of material from two major sediment sources within headwater channels was estimated: headcut erosion and bank erosion. Repeat surveys of channel headcuts were conducted; measurements of channel geometry were used in conjunction with bank erosion measurements in a bank migration model to estimate bank erosion for the length of the channel. High amounts of variability were found in the measured stream parameters and eroded volumes both within each catchment and across the four catchments, but values were within one order of magnitude for all four study watersheds. Results also showed that though migration rates were similar in headcuts and bank bends, bank erosion totals were much higher than headcut erosion totals for three of the four catchments and roughly equal in the remaining catchment. Values ranged from 0.89 m3 to 4.24 m3 per year for total headcut erosion and 1.43 m3 to 23.61m3 per year for total bank erosion in the four study catchments. Finally, a scaled down version of a linear meander migration model based on the sediment continuity equation, shows potential as a tool for managers to estimate bank erosion, as it appears to give reasonable values using a few relatively simple to measure model inputs.

    • Thesis
    • Peer Reviewed
    UC Merced Electronic Theses and Dissertations (2017)

    The work presented herein examines how and to what extent turbidity, channel bed movement and stream source water ratios change over different temporal scales in four forested mountain headwater catchments in the Sierra Nevada, California. This work focuses on the water quality topics of sediment and source waters as part of a larger study on the effects of forest fuels treatments. No effects on water quality were expected because treatments were set far back from the stream channel and relatively light (8.0% and 7.5% decrease in mean Leaf Area Index (LAI) for the northern and southern site respectively). Therefore, this work was designed to characterize sediment and source waters rather than explore treatment impacts. In doing so important insights were gained around sediment and stream water sources.

    Sediment movement was found to be highly episodic and tied to low-frequency, short-duration discharge events with pronounced seasonality. Turbidity hysteresis patterns indicated localized (bed and banks) sediment sources that were mobilized quickly but became progressively depleted. Continuous measurement of channel bed elevations in the thalweg pointed to seasonal mobilization (connectedness) of sediment during winter, a gradual depletion through spring and early summer, and disconnectedness in low flow season when material builds up again at the base of banks mirroring patterns seen in the turbidity hysteresis loops. Stream water chemistry data showed higher concentrations during base flow, which was exacerbated by consecutive years of drought. The high base flow ion concentrations were tied to high ratios of groundwater. End-member mixing analysis showed that wet and dry years had similar source water ratios during high flow (winter and spring) but during the low flow season (late summer), a shift toward higher ratios of groundwater was seen for drought years. Recent tree mortality observed across the Sierra Nevada after four consecutive years of drought underscores the critical role of groundwater in maintaining baseflow and sustaining forest ecosystems. Better understanding of sediment processes, source water contributions, and drought effects in small, forested, mountain, headwater catchments provides an important foundation for sustainable land use management, more effective channel restoration design, and improved mitigation of downstream water quality.

      Cover page: WATER QUALITY IN FORESTED MOUNTAIN STREAMS: AN INVESTIGATION INTO SEDIMENT PRODUCTION, SEDIMENT TRANSPORT, AND SOURCE WATERS IN HEADWATER CATCHMENTS OF THE SIERRA NEVADA, CALIFORNIACreative Commons 'BY' version 4.0 license
      • Article
      • Peer Reviewed
      UC Irvine Previously Published Works (2020)
      OBJECTIVE: Pediatric chronic pain evaluation includes self-reports and/or caregiver proxy-reports across biopsychosocial domains. Limited data exist on the effects of caregiver-child discrepancies in pediatric pain assessment. In children with chronic pain, we examined associations among discrepancies in caregiver-child reports of child anxiety and depressive symptoms and child functional impairment. METHODS: Participants were 202 children (Mage=14.49 ± 2.38 years; 68.8% female) with chronic pain and their caregivers (95.5% female). Children and caregivers completed the Revised Child Anxiety and Depression Scale (RCADS) and RCADS-Parent, respectively. Children also completed the Functional Disability Inventory. Mean difference tests examined caregiver-child discrepancies. Moderation analyses examined whether associations between child self-reported anxiety and depressive symptoms and functional impairment varied as a function of caregiver proxy-report. RESULTS: Children reported more anxiety and depressive symptoms compared with their caregivers proxy-reports (Z = -4.83, p < .001). Both informants reports of child anxiety and depressive symptoms were associated with child functional impairment (rs = .44, rs = .30, p < .001). Caregiver proxy-report moderated associations between child-reported anxiety and depressive symptoms and functional impairment (B = -0.007, p = .003). When caregiver proxy-report was low, child self-reported anxiety and depressive symptoms were positively related to functional impairment (B = 0.28, SE = 0.07, 95% CI [0.15, 0.41], p < .001). CONCLUSIONS: Discrepant caregiver-child perceptions of child anxiety and depressive symptoms may be associated with functioning in children with chronic pain, especially when caregivers report less child internalizing symptoms. These findings highlight the need for further examination of the effects of caregiver-child discrepancies on pediatric chronic pain outcomes and may indicate targets for intervention.
        Cover page: Caregiver-Child Discrepancies in Reports of Child Emotional Symptoms in Pediatric Chronic Pain.
        • Article
        • Peer Reviewed
        UC Merced Previously Published Works (2014)
        Seasonal turbidity patterns and event-level hysteresis analysis of turbidity verses discharge in four 1 km2 headwater catchments in California's Sierra Nevada indicate localized in-channel sediment sources and seasonal accumulation-depletion patterns of stream sediments. Turbidity signals were analyzed for three years in order to look at the relationships between seasonal turbidity trends, event turbidity patterns, and precipitation type to stream sediment production and transport. Seasonal patterns showed more turbidity events associated with fall and early to mid- winter events than with peak snow-melt. No significant turbidity patterns emerged for periods of snow melt vs. rain. Single event hysteresis loops showed clockwise patterns were dominant suggesting local sediment sources. In successive discharge events, the largest turbidity spike was often associated with the first but not necessarily the largest discharge event-indicating seasonal depletion of local sediment stores. In multi-peaked discharge events, hysteresis loops shifted from clockwise to linear or random patterns suggesting that localized sediment stores are being used up and sufficient flow energy must be reached to start entraining the more consolidated bank/bed sediment or that dominant sediment sources may be shifting to less localized areas such as hill slopes. A conceptual model with phases of accumulation and transport is proposed.
          • Article
          • Peer Reviewed
          UC Irvine Previously Published Works (2022)
          Pediatric patients with invisible symptomology, such as chronic pain syndromes, are more likely to experience pain-related stigma and associated discrimination by others, including medical providers, peers, school personnel, and family members. The degree of this pain-related stigma may depend on several social dimensions, including observer (e.g., attentional and implicit biases) and patient characteristics (e.g., racial identity, socioeconomic stressors). In this mini-review, we introduce the concept of pain-related stigma, and the intersectionality of stigma, within the context of social determinants of health in pediatric pain populations. Stigma theory, observer attentional biases, healthcare provider implicit/explicit biases, adverse childhood experience, and psychophysiology of socio-environmental stressors are integrated. Several ethical, clinical, and research implications are also discussed. Because the study of pain-related stigma in pediatric pain is in its infancy, the purpose of this conceptual review is to raise awareness of the nuances surrounding this social construct, propose avenues through which stigma may contribute to health inequities, present frameworks to advance the study of this topic, and identify areas for further investigation.
            Cover page: Pain-related stigma as a social determinant of health in diverse pediatric pain populations.Creative Commons 'BY' version 4.0 license
            • Article
            • Peer Reviewed
            UC Irvine Previously Published Works (2024)
            BACKGROUND: Paediatric laceration repair procedures are common in the ED; however, post-discharge recovery remains understudied. Perioperative research demonstrates that children exhibit maladaptive behavioural changes following stressful and painful medical procedures. This study examined post-discharge recovery following paediatric laceration repair in the ED. METHODS: This prospective observational study included a convenience sample of 173 children 2-12 years old undergoing laceration repair in a paediatric ED in Orange, California, USA between April 2022 and August 2023. Demographics, laceration and treatment data (eg, anxiolytic medication), and caregiver-reported child pre-procedural and procedural pain (Numerical Rating Scale (NRS)) were collected. On days 1, 3, 7 and 14 post-discharge, caregivers reported childrens pain and new-onset maladaptive behavioural changes (eg, separation anxiety) via the Post Hospitalization Behavior Questionnaire for Ambulatory Surgery. Univariate and logistic regression analyses were conducted to identify variables associated with the incidence of post-discharge maladaptive behavioural change. RESULTS: Post-discharge maladaptive behavioural changes were reported in 43.9% (n=69) of children. At 1 week post-discharge, approximately 20% (n=27) of children exhibited maladaptive behavioural changes and 10% (n=13) displayed behavioural changes 2 weeks post-discharge. Mild levels of pain (NRS ≥2) were reported in 46.7% (n=70) of children on post-discharge day 1, 10.3% (n=14) on day 7 and 3.1% (n=4) on day 14. An extremity laceration (p=0.029), pre-procedural midazolam (p=0.020), longer length of stay (p=0.043) and post-discharge pain on day 1 (p<0.001) were associated with incidence of maladaptive behavioural changes. Higher pain on post-discharge day 1 was the only variable independently associated with an increased likelihood of maladaptive behavioural change (OR=1.32 (95% CI 1.08 to 1.61), p=0.001). CONCLUSION: Over 40% of children exhibited maladaptive behavioural changes after ED discharge. Although the incidence declined over time, 10% of children continued to exhibit behavioural changes 2 weeks post-discharge. Pain on the day following discharge emerged as a key predictor, highlighting the potential critical role of proactive post-procedural pain management in mitigating adverse behavioural changes.
              Cover page: Paediatric laceration repair in the emergency department: post-discharge pain and maladaptive behavioural changes.
              • Article
              • Peer Reviewed
              UC Irvine Previously Published Works (2021)

              Background and objective

              The goal of the present study was to determine the incidence of new onset maladaptive behaviours in paediatric emergency department (PED) patients during the COVID-19 pandemic and to examine whether child and parent anxiety and parental health status were predictors for the new-onset of maladaptive behaviours.

              Methods

              Participants included child-parent dyads seen in a PED following the state's issuance of mandatory stay-at-home orders on 19 March 2020. A total of 351 children age 0-25 years and 335 parents enrolled in the study. Parents provided baseline demographic data and completed standardised surveys that assessed aspects of parental and child anxiety and parental health, as well as child new-onset maladaptive behaviours. Children ≥8 years of age completed surveys that assessed child anxiety.

              Findings

              Parents reported the new onset of maladaptive behaviours in children during the pandemic with frequencies up to 43%. Bivariate analysis identified predictors such as child anxiety (t(96) = -2.04, P = 0.044) as well as parental variables such as state anxiety (t(190) = -4.91, P < 0.001) and parental sensitivity to anxiety (t(243) = -3.19, P = 0.002). A logistic regression model identified parent mental health and COVID-19 anxiety as predictors of new onset maladaptive behaviours in children (X2 (6) = 42.514, P < 0.001). Specifically, every unit change in parental anxiety of COVID-19 was associated with a unit increase in maladaptive behaviours in children.

              Conclusions

              We identified distinct parent and child-related factors that predicted new onset child maladaptive behaviours during the COVID-19 pandemic. The identification of such predictors may help clinicians to prevent maladaptive responses to the pandemic quarantine.
                Cover page: Predictors for COVID‐19‐related new‐onset maladaptive behaviours in children presenting to a paediatric emergency department
                • Article
                • Peer Reviewed
                UC Irvine Previously Published Works (2013)

                Objective

                Children experience distress after surgery. Associations exist between parent reassurance (e.g., "It's OK") and child distress, but little is known about the causal direction of these interactions. This study examined sequential relations between mothers' and fathers' reassurance and children's distress.

                Methods

                146 families with 2- to 11-year-olds undergoing elective surgery participated. Time-event coding and time-window sequential analysis examined whether reassurance preceded or followed child distress. Secondary analyses examined the relation of child sex and parent anxiety with the reassurance/distress contingency.

                Results

                Reassurance was positively correlated with distress; however, nonverbal distress was less likely to start following reassurance and was also more likely to continue following reassurance. Mothers were more likely to reassure following boys' verbal distress, and mothers with higher anxiety were more likely to reassure following nonverbal distress.

                Conclusions

                Whereas parental reassurance may prevent the start of child distress, it might maintain ongoing child distress.
                  Cover page: Sequential Analysis of Mothers’ and Fathers’ Reassurance and Children’s Postoperative Distress
                  • Article
                  • Peer Reviewed
                  UC Irvine Previously Published Works (2019)
                  Objective To conduct a single-arm pilot study assessing the feasibility and acceptability of a 30-day parent-focused mindfulness and psychosocial support mobile app intervention for parents of children with chronic pain. Methods Thirty parents completed the intervention, which included a mindfulness curriculum, peer support videos, and written psychoeducational content. Twelve healthcare providers also assessed the app and provided feedback. Feasibility was assessed by server-side documented usage on ≥50% of the days in the intervention period and completion of ≥70% of the mindfulness content. Parent and provider acceptance were assessed by ≥70% of participants rating each acceptance test question as ≥5 on a 7-point Likert scale. Parents completed measures of solicitousness, stress, mindful parenting, and resilience prior to and following the intervention. Results Feasibility results were mixed: parents completed mindfulness content on an average of 11.2 days during the intervention period, slightly under the pre-established criterion. However, parents completed an average of 72.1% of the content, which met feasibility criterion. Acceptance criteria were met for the majority of parent acceptance test questions and all of the provider acceptance test questions. Exploratory analyses of the psychosocial measures revealed significant decreases in parental solicitous behavior and perceived stress, and a significant increase in mindful parenting. Conclusions The current study extends the emerging body of research on mindfulness-based interventions for parents of children with chronic illness and suggests that it may be acceptable to deliver this content through a mobile device. Future research is needed to assess the interventions efficacy compared to standard of care.
                    Cover page: Feasibility and Acceptance Testing of a Mobile Application Providing Psychosocial Support for Parents of Children and Adolescents With Chronic Pain: Results of a Nonrandomized Trial.
                    • Article
                    • Peer Reviewed
                    UC Irvine Previously Published Works (2019)
                    OBJECTIVE: The goal of the study was to describe the experiences of adolescents with irritable bowel syndrome (IBS) from the perspective of adolescents, their parents, and health care providers who treat adolescents who have IBS. DESIGN: The study consisted of semistructured interviews. SETTING: Participants were recruited from multidisciplinary pain clinics. SUBJECTS: Thirty-six people participated in the study: 12 adolescents, 12 parents, and 12 health care providers. RESULTS: Two main themes associated with the impact of IBS on adolescents social functioning emerged from the qualitative interview data: 1) disconnection from peers and 2) strain on family relationships, with subthemes reflecting the perspectives of adolescents, parents, and health care providers. CONCLUSIONS: Participants in our study described that adolescents with IBS encounter significant peer- and family-related social stress. Helpful interventions may be those that focus on social support from other adolescents with similar conditions, as well as family-based therapeutic interventions.
                      Cover page: Pediatric Irritable Bowel Syndrome: Perspectives on Pain and Adolescent Social Functioning.
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