Now showing items 9433-9452 of 12955

    • Q&A: Evolutionary capacitance

      Masel, Joanna; Ecology and Evolutionary Biology, University of Arizona, 1041 E. Lowell St, Tucson, AZ 84721, USA (BioMed Central, 2013)
    • QBO/solar modulation of the boreal winter Madden-Julian oscillation: A prediction for the coming solar minimum

      Hood, Lon L.; Univ Arizona, Lunar & Planetary Lab; Lunar and Planetary Laboratory; University of Arizona; Tucson Arizona USA (AMER GEOPHYSICAL UNION, 2017-04-28)
      The Madden-Julian oscillation (MJO), also known as the 30-60day oscillation, is the strongest of the intraseasonal climate oscillations in the tropics and has significant derivative effects on extratropical circulation and intraseasonal climate. It has recently been shown that the stratospheric quasi-biennial oscillation (QBO) modulates the amplitude of the boreal winter MJO such that MJO amplitudes are larger on average during the easterly phase (QBOE) than during the westerly phase (QBOW). A major possible mechanism is the decrease in static stability in the lowermost stratosphere under QBOE conditions resulting from relative upwelling associated with the QBO-induced meridional circulation. Here evidence is presented that tropical upwelling changes related to the 11year solar cycle also modulate the boreal winter MJO. Based on 37.3years of MJO amplitude data, the largest amplitudes and occurrence rates, and the weakest static stabilities in the tropical lower stratosphere, occur during the QBOE phase under solar minimum (SMIN) conditions while the smallest amplitudes and strongest static stabilities occur during the QBOW phase under solar maximum (SMAX) conditions. Conversely, when the QBO and solar forcings are opposed (QBOW/SMIN and QBOE/SMAX), the difference in occurrence rates becomes statistically insignificant. During the coming solar minimum, at least one additional winter in the QBOE/SMIN category should occur (possibly as early as 2017/2018) during which especially large MJO amplitudes are expected and an initial test of these results will be possible. Plain Language Summary An ongoing issue in climate science is the extent to which upper atmospheric processes, including solar forcing, can influence tropospheric climate. It has recently been shown that an internal oscillation of the stratosphere, the quasi-biennial oscillation, can modulate the amplitude and occurrence rate of intraseasonal climate oscillations in the tropical Pacific during northern winter. These intraseasonal oscillations, the most important of which is the 30-60day Madden-Julian oscillation, have significant derivative effects on climate outside of the tropics, including impacts on rainfall events over the continental United States. Here evidence is presented that the amplitude of the Madden-Julian oscillation during northern winter is also modulated by the 11year solar cycle. The modulation is such that amplitudes and occurrence rates are largest under solar minimum conditions when the quasi-biennial oscillation is in its easterly phase and smallest under solar maximum conditions when the quasi-biennial oscillation is in its westerly phase. However, the available time record (37.3years of satellite measurements) is limited. During the coming solar minimum, at least one additional winter in the solar minimum/easterly category should occur (possibly as early as 2017/2018) during which larger-than-average amplitudes are expected and an initial test of the proposed relationship will be possible.
    • QKD-enhanced Cybersecurity Protocols

      Djordjevic, I.B.; College of Engineering, University of Arizona (Institute of Electrical and Electronics Engineers Inc., 2021)
      Security of QKD is guaranteed by the quantum mechanics laws rather than unproven assumptions employed in computational cryptography. Unfortunately, the secret-key rates are way too low and transmission distances are limited. The post-quantum cryptography (PQC) is proposed as an alternative to QKD. However, the PQC protocols are based on conjecture that there are no polynomial time algorithms to break the PQC protocols. To overcome key challenges of both post-quantum cryptography and QKD, we propose to use the QKD only in initialization stage to set-up corresponding cybersecurity protocols. The proposed concept is applied to both computational security and PQC protocols. The proposed QKD-enhanced cybersecurity protocols are tolerant to attacks initiated by quantum computers. CCBYNCND
    • Quadratic discriminant analysis by projection

      Wu, Ruiyang; Hao, Ning; Department of Mathematics, The University of Arizona (Elsevier BV, 2022-07)
      Discriminant analysis, including linear discriminant analysis (LDA) and quadratic discriminant analysis (QDA), is a popular approach to classification problems. It is well known that LDA is suboptimal to analyze heteroscedastic data, for which QDA would be an ideal tool. However, QDA is less helpful when the number of features in a data set is moderate or high, and LDA and its variants often perform better due to their robustness against dimensionality. In this work, we introduce a new dimension reduction and classification method based on QDA. In particular, we define and estimate the optimal one-dimensional (1D) subspace for QDA, which is a novel hybrid approach to discriminant analysis. The new method can handle data heteroscedasticity with number of parameters equal to that of LDA. Therefore, it is more stable than the standard QDA and works well for data in moderate dimensions. We show an estimation consistency property of our method, and compare it with LDA, QDA, regularized discriminant analysis (RDA) and a few other competitors by simulated and real data examples.
    • Quadratic mathematical modeling of sustainable dry beneficiation of kaolin

      Hayat, M.B.; Danishwar, M.; Hamid, A.; Zaid, M.M.; Emad, M.Z.; Department of Mining and Geological Engineering, The University of Arizona (MDPI AG, 2021)
      Clay minerals are one of the most utilized minerals among non-metals. These are hydrous aluminum silicates with a layer (sheet-like) structure. Kaolin is a hydrous aluminosilicate mineral with a thin platelet structure. Kaolin is extensively used in paper, paint, and many other industries. Wet processing of kaolin will not be sustainable over the long term because global freshwater resources are becoming scarce. Hence, a process is necessary that does not consume water during the beneficiation of kaolin. This study developed a dry beneficiation process for low-grade kaolin of 59.6%, with 12% quartz and about 6% titaniferous impurities from Nagar Parkar, Sindh province, Pakistan. To develop a size difference between kaolinite and impurities, steel balls clad with rubber were used as the grinding media in a selective grinding unit. Screens of 60 and 400 mesh were employed to classify the feed of air classifier. Oversize +60 mesh was reground, 400 to 60 mesh fractions were sent to an air classifier, and −400 mesh was considered to be a product with the grade and recovery of 90.6% and 20.5%, respectively. Air classifier experiments were designed using central composite design. An experiment using a fan speed of 1200 rpm and a shutter opening of 4.0 showed optimum results, with maximum kaolinite grade and recovery of 91.5% and 35.9%, respectively. The statistical models developed for grade and recovery predicted the optimum results at a fan speed of 1251 rpm and shutter opening of 3.3 with the maximum kaolinite grade recovery of 91.1% and 24.7%, respectively. The differences between experimental and predicted grade and recovery were 0.1% and 2.4%, respectively. The characterization results showed the total upgrade of kaolin from 59.6% to 91.2%, with 27.1% recovery. The designed methodology has the potential to improve the yield of the product by focusing on its recovery. Furthermore, the designed process can be improved by using different sized balls in the selective grinding unit. This beneficiation process can utilize more than one air classifier in series to achieve the targeted results. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
    • A qualitative analysis of vaccine decision makers' conceptualization and fostering of 'community engagement' in India

      Dutta, Tapati; Meyerson, Beth E; Agley, Jon; Barnes, Priscilla A; Sherwood-Laughlin, Catherine; Nicholson-Crotty, Jill; Univ Arizona, Coll Med, Coll Social & Behav Sci Family & Community Med, Southwest Inst Res Women (BMC, 2020-10-20)
      Background Globally, and in India, research has highlighted the importance of community engagement in achieving national vaccination goals and in promoting health equity. However, community engagement is not well-defined and remains an underutilized approach. There is also paucity of literature on community engagement's effectiveness in achieving vaccination outcomes. To address that gap, this study interviewed Indian vaccination decision makers to derive a shared understanding of the evolving conceptualization of community engagement, and how it has been fostered during India's Decade of Vaccines (2010-2020). Methods Semi-structured interviews were conducted with 25 purposefully sampled national-level vaccine decision makers in India, including policymakers, immunization program heads, and vaccine technical committee leads. Participants were identified by their 'elite' status among decisionmakers in the Indian vaccination space. Schutz' Social Phenomenological Theory guided development of an a priori framework derived from the Social Ecological Model. The framework helped organize participants' conceptualizations of communities, community engagement, and related themes. Inter-rater reliability was computed for a subsample of coded interviews, and findings were validated in a one-day member check-in meeting with study participants and teams. Results The interviews successfully elucidated participants' understanding of key terminology ("community") and approaches to community engagement propagated by the vaccine decision makers. Participants conceptualized 'communities' as vaccine-eligible children, their parents, frontline healthcare workers, and vaccination influencers. Engagement with those communities was understood to mean vaccine outreach, capacity-building of healthcare workers, and information dissemination. However, participants indicated that there were neither explicit policy guidelines defining community engagement nor pertinent evaluation metrics, despite awareness that community engagement is complex and under-researched. Examples of different approaches to community engagement ranged from vaccine imposition to empowered community vaccination decision-making. Finally, participants proposed an operational definition of community engagement and discussed concerns related to implementing it. Conclusions Although decision makers had different perceptions about what constitutes a community, and how community engagement should optimally function, the combined group articulated its importance to ensure vaccination equity and reiterated the need for concerted political will to build trust with communities. At the same time, work remains to be done both in terms of research on community engagement as well as development of appropriate implementation and outcome metrics.
    • Qualitative Coding in the Computational Era: A Hybrid Approach to Improve Reliability and Reduce Effort for Coding Ethnographic Interviews

      Li, Z.; Dohan, D.; Abramson, C.M.; University of Arizona (SAGE Publications Inc., 2021)
      Sociologists have argued that there is value in incorporating computational tools into qualitative research, including using machine learning to code qualitative data. Yet standard computational approaches do not neatly align with traditional qualitative practices. The authors introduce a hybrid human-machine learning approach (HHMLA) that combines a contemporary iterative approach to qualitative coding with advanced word embedding models that allow contextual interpretation beyond what can be reliably accomplished with conventional computational approaches. The results, drawn from an analysis of 87 human-coded ethnographic interview transcripts, demonstrate that HHMLA can code data sets at a fraction of the effort of human-only strategies, saving hundreds of hours labor in even modestly sized qualitative studies, while improving coding reliability. The authors conclude that HHMLA may provide a promising model for coding data sets where human-only coding would be logistically prohibitive but conventional computational approaches would be inadequate given qualitative foci. © The Author(s) 2021.
    • Qualitative Coding in the Computational Era: A Hybrid Approach to Improve Reliability and Reduce Effort for Coding Ethnographic Interviews

      Li, Zhuofan; Dohan, Daniel; Abramson, Corey M.; University of Arizona, School of Sociology (SAGE Publications, 2021-12-06)
      Sociologists have argued that there is value in incorporating computational tools into qualitative research, including using machine learning to code qualitative data. Yet standard computational approaches do not neatly align with traditional qualitative practices. The authors introduce a hybrid human-machine learning approach (HHMLA) that combines a contemporary iterative approach to qualitative coding with advanced word embedding models that allow contextual interpretation beyond what can be reliably accomplished with conventional computational approaches. The results, drawn from an analysis of 87 human-coded ethnographic interview transcripts, demonstrate that HHMLA can code data sets at a fraction of the effort of human-only strategies, saving hundreds of hours labor in even modestly sized qualitative studies, while improving coding reliability. The authors conclude that HHMLA may provide a promising model for coding data sets where human-only coding would be logistically prohibitive but conventional computational approaches would be inadequate given qualitative foci.
    • Qualitative research on maternal care access among Arabic-speaking refugee women in the USA: Study protocol

      Yeo, S.; Magrath, P.; Alaofè, H.; Okechukwu, A.; Department of Health Promotion Sciences, University of Arizona Mel, Enid Zuckerman College of Public Health (BMJ Publishing Group, 2022)
      Background Refugees tend to have greater health needs and pre-existing medical conditions due to poor living conditions, lack of health services, exposure to a variety of risk factors, and a high level of stress and trauma prior to entry to a host country. Notwithstanding distinctive needs and inherent conditions, there is a paucity of literature on refugee maternal health, especially for Arabic-speaking refugee women resettled in the USA. Methods and analysis The paper delineates a qualitative study protocol to explore the experiences of Arabic-speaking refugee women in the USA when accessing maternal care. Informed by social cognitive theory, the study will employ two qualitative research methods; in-depth interviews and â € go-along' interviews with Arabic-speaking refugee women. Go-along interview will be used to elicit spatial experiences in situ to explore perceptions of environments among study participants and environmental and structural barriers. 20 refugee women who meet the inclusion criteria will be recruited through snowball sampling with support from community partners. Two researchers will code the transcription and fieldnotes using MAXQDA 2020 (VERBI Software, 2019). The analysis will involve deductive content analysis using a structured categorisation matrix based on the theory while also incorporating inductive codes that may emerge through the process. Ethics and dissemination The study has been reviewed and approved by the Human Subjects Protection Programme at the University of Arizona (IRB 2104716241). The study results will be condensed in a summary report, which will be shared with community partners, including refugee resettlement agencies and relevant staff at the state department. Also, community feedback will be garnered from the dissemination workshops to inform community discussions for actions and an intervention to address the identified needs. © 2022 BMJ Publishing Group. All rights reserved.
    • A Qualitative Study Describing Nurses' Experiences With Presenteeism

      Rainbow, Jessica G; Dudding, Katherine M; Bethel, Claire; College of Nursing, University of Arizona (Lippincott Williams and Wilkins, 31-03-20)
      OBJECTIVE: The aim of this study was to understand nurse awareness of coping and decision making regarding presenteeism and the consequences thereof. BACKGROUND: Nurses report high levels of presenteeism or not being able to fully function in the workplace, but we currently lack understanding of nurse perceptions of presenteeism and its consequences. METHODS: A qualitative descriptive method was used to evaluate the perceptions of nurses from medical surgical units at 2 different hospitals. FINDINGS: For purposes of the study, presenteeism was defined as being present at work when not fully engaged. Most respondents experienced presenteeism in the month before data collection. Five categories of themes were identified: 1) factors leading to presenteeism, 2) awareness and symptoms of presenteeism, 3) coping with presenteeism on and off shift, 4) decision making regarding presenteeism, and 5) consequences of presenteeism. CONCLUSIONS: Both personal and work factors contribute to presenteeism. To decrease presenteeism, healthcare leaders and systems should consider reviewing and changing sick/leave polices, unit cultures, and a lack of resources that contribute to and encourage an awareness of presenteeism, thereby decreasing nurse fatigue. Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.
    • A qualitative study of changes in expectations over time among patients with chronic low back pain seeking four CAM therapies

      Eaves, Emery R.; Sherman, Karen J.; Ritenbaugh, Cheryl; Hsu, Clarissa; Nichter, Mark; Turner, Judith A.; Cherkin, Daniel C.; Group Health Research Institute; Department of Family and Community Medicine & School of Anthropology, University of Arizona; Department of Psychiatry & Behavioral Sciences and Department of Rehabilitation Medicine, University of Washington School of Medicine (BioMed Central Ltd, 2015)
      BACKGROUND: The relationship between patient expectations about a treatment and the treatment outcomes, particularly for Complementary and Alternative Medicine (CAM) therapies, is not well understood. Using qualitative data from a larger study to develop a valid expectancy questionnaire for use with participants starting new CAM therapies, we examined how participants' expectations of treatment changed over the course of a therapy. METHODS: We conducted semi-structured qualitative interviews with 64 participants initiating one of four CAM therapies (yoga, chiropractic, acupuncture, massage) for chronic low back pain. Participants just starting treatment were interviewed up to three times over a period of 3 months. Interviews were transcribed verbatim and analyzed using a qualitative mixed methods approach incorporating immersion/crystallization and matrix analysis for a decontexualization and recontextualization approach to understand changes in thematic emphasis over time. RESULTS: Pre-treatment expectations consisted of conjecture about whether or not the CAM therapy could relieve pain and improve participation in meaningful activities. Expectations tended to shift over the course of treatment to be more inclusive of broader lifestyle factors, the need for long-term pain management strategies and attention to long-term quality of life and wellness. Although a shift toward greater acceptance of chronic pain and the need for strategies to keep pain from flaring was observed across participants regardless of therapy, participants varied in their assessments of whether increased awareness of the need for ongoing self-care and maintenance strategies was considered a "positive outcome". Regardless of how participants evaluated the outcome of treatment, participants from all four therapies reported increased awareness, acceptance of the chronic nature of pain, and attention to the need to take responsibility for their own health. CONCLUSIONS: The shift in treatment expectations to greater acceptance of pain and the need for continued self-care suggests that future research should explore how CAM practitioners can capitalize on these shifts to encourage feelings of empowerment rather than disappointment surrounding realizations of the need for continued engagement with self-care.
    • Quality Improvement and Safety in US Pharmacy Schools

      McManus, Katherine; Metrejean, Christina; Schweitzer, Kali; Cooley, Janet; Warholak, Terri; Univ Arizona, Coll Pharm (AMER ASSOC COLL PHARMACY, 2019-11-01)
      Objective. To catalog the methods in which quality improvement (QI) and safety are taught in schools and colleges of pharmacy in the United States and showcase exemplar QI programs. Methods. This descriptive, multi-phase study included an online questionnaire, syllabi review, and phone interviews. The study was approved by the University of Arizona Institutional Review Board (IRB). One representative from each US pharmacy school accredited by the Accreditation Council for Pharmacy Education (ACPE) was invited to participate. Participants indicated the type of QI education their school provided via online questionnaire. Following questionnaire completion, syllabi were requested from the schools and phone interviews were scheduled with a school representative to obtain additional information. From the data, exemplars were chosen using a predetermined, evidenced-based rubric. Results. Of the 136 schools contacted, 56 (41.2%) completed the survey. Of the responding schools reporting their QI and safety offerings, 41 (73.2%) had a required session/module; 24 (42.9%) had a required course; 21 (37.5%) had an elective course; 21 (37.5%) had an introductory pharmacy practice experience (IPPE), advanced pharmacy practice experience (APPE), or internship; 17 (30.4%) had a required project; 17 (30.4%) had interprofessional education integrated into their course; 15 (26.8%) had an error laboratory; and 11 (19.6%) offered postgraduate training. Conclusion. Many of the responding US schools of pharmacy expose students to some aspect of QI and/or safety, most often via class session or module. The exemplar programs serve as examples of how QI can be further integrated into pharmacy curricula.
    • Quality of life and functional vision across pediatric eye conditions assessed using the PedEyeQ

      Leske, David A; Hatt, Sarah R; Wernimont, Suzanne M; Castañeda, Yolanda S; Cheng-Patel, Christina S; Liebermann, Laura; Birch, Eileen E; Holmes, Jonathan M; Department of Ophthalmology and Vision Science, University of Arizona (Elsevier Inc., 2021-02-16)
      Purpose: To evaluate eye-related quality of life (ER-QOL) and functional vision across a wide range of pediatric eye conditions, using the Pediatric Eye Questionnaires (PedEyeQ). Methods: A total of 1,037 children with an eye condition and 254 visually normal controls, across 0-4, 5-11, and 12-17 years age groups, completed the following questionnaires: Child PedEyeQ (Functional Vision, Bothered by Eyes/Vision, Social, Frustration/Worry domains), Proxy PedEyeQ (same domains plus Eye Care), and Parent PedEyeQ (Impact on Parent and Family, Worry about Child's Eye Condition, Worry about Child's Self-perception and Interactions, and Worry about Functional Vision domains). The primary eye condition was classified as amblyopia (n = 171), cataract (n = 99), cerebral visual impairment (CVI; n = 50), cornea (n = 20), eyelid (n = 35), glaucoma (n = 24), nystagmus (n = 57), orbital (n = 19), pupil/iris (n = 7), refractive error (n = 119), retina (n = 82), strabismus (n = 332), and uveitis (n = 22). Results: PedEyeQ domain scores (scaled 0-100) were significantly worse across eye conditions, compared with controls. Child PedEyeQ greatest differences were on the Bothered by Eyes/Vision domain (nystagmus 5-11 years, −26 points [95% CI, −39 to −12]; nystagmus 12-17 years, −45 [95% CI, −61 to −28]). Proxy PedEyeQ differences were greatest on Functional Vision (CVI 0-4 years, −45 [95% CI, −56 to −34]; CVI 5-11 years, −58 [95% CI, −72 to −43]; nystagmus 12-17 years, −50 [95% CI, −69 to −31]). Parent PedEyeQ differences were greatest on Worry about Child's Functional Vision (CVI 0-4 years, −64; 95% CI −77 to −50). Conclusions: The PedEyeQ detects reduced ER-QOL and functional vision across pediatric eye conditions, and across age groups, indicating its utility for clinical practice and clinical trials. © 2021 American Association for Pediatric Ophthalmology and Strabismus
    • The Quality of Recovery after Dexamethasone, Ondansetron, or Placebo Administration in Patients Undergoing Lower Limbs Orthopedic Surgery under Spinal Anesthesia Using Intrathecal Morphine. A Randomized Controlled Trial

      Moro, Eduardo Toshiyuki; Ferreira, Miguel Antônio Teixeira; Gonçalves, Renyer Dos Santos; Vargas, Roberta Costa; Calil, Samira Joverno; Soranz, Maria Alice; Bloomstone, Joshua; Univ Arizona, Coll Med (HINDAWI LTD, 2020-05-20)
      Intrathecal morphine is widely and successfully used to prevent postoperative pain after orthopedic surgery, but it is frequently associated with side effects. The aim of this study was to evaluate the effect of dexamethasone or ondansetron when compared to placebo to reduce the occurrence of these undesirable effects and, consequently, to improve the quality of recovery based on patient's perspective. Methods. One hundred and thirty-five patients undergoing lower extremity orthopedic surgery under spinal anesthesia using bupivacaine and morphine were randomly assigned to receive IV dexamethasone, ondansetron, or saline. On the morning following surgery, a quality of recovery questionnaire (QoR-40) was completed. Results. No differences were detected in the global and dimensional QoR-40 scores following surgery; however, following postanesthesia care unit (PACU) discharge, pain scores were higher in patients receiving ondansetron compared with patients who received dexamethasone. Conclusion. Neither ondansetron nor dexamethasone improves the quality of recovery after lower limbs orthopedic surgery under spinal anesthesia using intrathecal morphine.
    • Quality standards, implementation autonomy, and citizen satisfaction with public services: cross-national evidence

      Song, Miyeon; An, Seung-Ho; Meier, Kenneth J.; Univ Arizona, Sch Govt (ROUTLEDGE JOURNALS, TAYLOR & FRANCIS LTD, 2020-02-27)
      This article investigates whether citizens' evaluations of service performance are related to archival measures of performance, and how institutional context shapes this relationship contingent on administrative autonomy - standards, human resources, and financial autonomy. Using cross-national education data, this study finds that student performance is positively associated with parental evaluations of schools. Perceptions are more closely aligned with performance when agencies have greater autonomy in managing employees, and when national-level bureaucracies set performance standards. This research advances our understanding of the role of administrative autonomy in citizen satisfaction and provides implications for the institutional designs that can benefit performance assessment.
    • Quantal Risk Assessment Database: A Database for Exploring Patterns in Quantal Dose-Response Data in Risk Assessment and its Application to Develop Priors for Bayesian Dose-Response Analysis

      Wheeler, Matthew W; Piegorsch, Walter W; Bailer, Albert John; Univ Arizona, Interdisciplinary Program Stat (WILEY, 2019-03-01)
      Quantitative risk assessments for physical, chemical, biological, occupational, or environmental agents rely on scientific studies to support their conclusions. These studies often include relatively few observations, and, as a result, models used to characterize the risk may include large amounts of uncertainty. The motivation, development, and assessment of new methods for risk assessment is facilitated by the availability of a set of experimental studies that span a range of dose-response patterns that are observed in practice. We describe construction of such a historical database focusing on quantal data in chemical risk assessment, and we employ this database to develop priors in Bayesian analyses. The database is assembled from a variety of existing toxicological data sources and contains 733 separate quantal dose-response data sets. As an illustration of the database's use, prior distributions for individual model parameters in Bayesian dose-response analysis are constructed. Results indicate that including prior information based on curated historical data in quantitative risk assessments may help stabilize eventual point estimates, producing dose-response functions that are more stable and precisely estimated. These in turn produce potency estimates that share the same benefit. We are confident that quantitative risk analysts will find many other applications and issues to explore using this database.
    • Quantification and Analysis of Micro-Level Activities Data from Children Aged 1–12 Years Old for Use in the Assessments of Exposure to Recycled Tire on Turf and Playgrounds

      Lopez-Galvez, N.; Claude, J.; Wong, P.; Bradman, A.; Hyland, C.; Castorina, R.; Canales, R.A.; Billheimer, D.; Torabzadeh, E.; Leckie, J.O.; et al. (MDPI, 2022)
      Background: There are growing health concerns about exposure to toxicants released from recycled tire rubber, which is commonly used in synthetic turf and playground mats. To better estimate children’s exposure and risk from recycled tire rubber used in synthetic turf and playground mats, there is a need to collect detailed accurate information on mouthing activity and dermal contact behaviors. The objective of this study was to quantify and analyze micro-level activity time series (MLATS) data from children aged 1–12 years old while playing (non-sport-related games) at turf-like locations and playgrounds. Another objective was to estimate the incidental ingestion rate of rubber crumb among children. Methods: Hand and mouth contact frequency, hourly duration, and median contact duration with different objects were calculated for children playing on turf (i.e., parks, lawns, and gardens) (n = 56) and for children playing on playground structures (n = 24). Statistically significant differences between males and females as well as children’s age groups were evaluated. The daily incidental ingestion rate of rubber crumb was calculated. Results: For children playing on turf, there were significant differences between younger (1–6 y) and older (7–12 y) children for the mouthing median duration with non-dietary objects and all objects. For children playing on playground structures, we found significant mouthing frequency differences between younger (1–6 y) and older children (7–12 y) with all objects, and for mouthing median duration with non-dietary objects. There were no significant differences between males and females playing on artificial turf-like surfaces or playground mats. Our estimated mean incidental ingestion rate was 0.08, 0.07, and 0.08 g rubber crumb/day for children <2, 2–6, and 6–11 years old, respectively. Discussion: our results suggest that age and contact duration should be considered in risk assessment models to evaluate mouthing activities when children are playing on artificial turf surfaces or playground mats. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.
    • Quantification of corrections for the main lunisolar nutation components and analysis of the free core nutation from VLBI-observed nutation residuals

      Zhu, Ping; Triana, Santiago Andrés; Rekier, Jerémy; Trinh, Antony; Dehant, Véronique; Lunar and Planetary Laboratory, University of Arizona (Springer Science and Business Media LLC, 2021-04-23)
      The attempt to quantify the corrections of lunisolar nutation components was made after analysis of six sets of Earth’s orientation parameters (EOP). The deviations of the long-term nutation components about IAU2006/IAU2000A precession–nutation model are consistent with the uncertainties suggested by Mathews et al. (J Geophys Res Solid Earth, 2002., but they exceed the errors determined in this work. The corrections are validated using the IERS 14C04 and IVS 19q4e combined solutions. After applying the corrections found in this work to the 14C04 nutation residuals, we analyzed the remaining signals, which contain the signature of the free core nutation (FCN). The eigenperiod of the FCN is fixed to the value derived from the resonance of the non-hydrostatic earth model in a priori. The amplitude of FCN is computed by fitting observations to the empirical model using a sliding window, the length of window is determined by taking into account the interference between those close nutation components and the FCN. In addition, we also fitted the nutation residuals by a viscous damping function; both methods produce the same results in the amplitudes of FCN. The magnitude of the free core nutation bears a “V-shape” distribution, and furthermore, the oscillation of the FCN shows a decay and a steady reinforcement before and after 1999. In order to examine the origin of the modulation in FCN’s magnitude, we briefly analyzed the possible damping or beating mechanism behind it. We diagnosed the magnitude and running phase changes of FCN by comparing it with the occurrence of the transient geomagnetic jerks. The weighted root mean square errors of nutation residuals are minimally reduced about 36 % when the corrections to the 21 nutation components and the FCN signature are considered together.
    • Quantification of Elemental Contaminants in Unregulated Water across Western Navajo Nation

      Credo, Jonathan; Torkelson, Jaclyn; Rock, Tommy; Ingram, Jani C; Univ Arizona, Coll Med, Clin Translat Sci Grad Program (MDPI, 2019-07-31)
      The geologic profile of the western United States lends itself to naturally elevated levels of arsenic and uranium in groundwater and can be exacerbated by mining enterprises. The Navajo Nation, located in the American Southwest, is the largest contiguous Native American Nation and has over a 100-year legacy of hard rock mining. This study has two objectives, quantify the arsenic and uranium concentrations in water systems in the Arizona and Utah side of the Navajo Nation compared to the New Mexico side and to determine if there are other elements of concern. Between 2014 and 2017, 294 water samples were collected across the Arizona and Utah side of the Navajo Nation and analyzed for 21 elements. Of these, 14 elements had at least one instance of a concentration greater than a national regulatory limit, and six of these (V, Ca, As, Mn, Li, and U) had the highest incidence of exceedances and were of concern to various communities on the Navajo Nation. Our findings are similar to other studies conducted in Arizona and on the Navajo Nation and demonstrate that other elements may be a concern for public health beyond arsenic and uranium.
    • Quantification of intracellular HNO delivery with capillary zone electrophoresis

      Amarakoon, Thilini N.; Ke, Neng; Aspinwall, Craig A.; Miranda, Katrina M.; Department of Chemistry and Biochemistry, University of Arizona; BIO5 Institute, University of Arizona; Department of Biomedical Engineering, University of Arizona (Elsevier BV, 2022-01)
      Redox signaling, wherein reactive and diffusible small molecules are channeled into specific messenger functions, is a critical component of signal transduction. A central principle of redox signaling is that the redox modulators are produced in a highly controlled fashion to specifically modify biotargets. Thiols serve as primary mediators of redox signaling as a function of the rich variety of adducts, which allows initiation of distinct cellular effects. Coupling the inherent reactivity of thiols with highly sensitive and selective chemical analysis protocols can facilitate identification of redox signaling agents, both in solution and in cultured cells. Here, we describe use of capillary zone electrophoresis to both identify and quantify sulfinamides, which are specific markers of the reaction of thiols with nitroxyl (HNO), a putative biologically relevant reactive nitrogen species.