Now showing items 1-20 of 7489

    • Environmental stress and human life history strategy development in rural and peri-urban South India

      Richardson, George B.; Placek, Caitlyn; Srinivas, Vijaya; Jayakrishna, Poornima; Quinlan, Robert; Madhivanan, Purnima; Univ Arizona, Dept Hlth Promot Sci (ELSEVIER SCIENCE INC, 2020-05)
      Few studies have examined the role of early vs. later environment in the development of life history (LH) strategies, whether age at sexual debut mediates LH development, or whether LH indicators contribute to environmental stress in adulthood. In the current study, we addressed these gaps cross-culturally using data from Jenu Kurubas who live in the rural outskirts of Mysore (n = 133), India, and mixed-caste peri-urban residents in Mysore city (n = 222). Research took place from October 2016-July 2017. First, participants engaged in semi-structured interviews to formulate quantitative measures of current environmental stress (n = 60). Next, participants (n = 355) completed structured questionnaires that measured demographics; early and current environmental stress; and LH indicators including age at sexual debut, facets of impulsivity, education, and number of children. Structural equation modeling was used to test for the developmental cascade reported in Western studies of psychosocial acceleration (e.g., indirect effect of early environmental stress on number of children through age at sexual debut). Consistent with Western findings, environmental stress appeared to hasten sexual debut, decrease self-regulation and educational attainment, and increase current environmental stress in the peri-urban sample. Early environmental stress forecasted younger age at sexual debut in both samples; however, no other effects of early environmental stress nor any associations with current environmental stress were consistent between samples. Although age at sexual debut appeared to translate early environmental stress into greater numbers of children and current environmental stress in the peri-urban and rural samples, respectively, it was associated with different outcomes between the samples and forecasted adult environment only in the rural sample. Taken together, our findings indicate more research is needed to determine whether the developmental cascade suggested by most applications of LH theory to humans generalizes across cultures and rural and periurban environments.
    • 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.
    • The Disturbed Iron Phenotype of Tumor Cells and Macrophages in Renal Cell Carcinoma Influences Tumor Growth

      Schnetz, Matthias; Meier, Julia K; Rehwald, Claudia; Mertens, Christina; Urbschat, Anja; Tomat, Elisa; Akam, Eman A; Baer, Patrick; Roos, Frederik C; Brüne, Bernhard; et al. (MDPI, 2020-02-25)
      Accumulating evidence suggests that iron homeostasis is disturbed in tumors. We aimed at clarifying the distribution of iron in renal cell carcinoma (RCC). Considering the pivotal role of macrophages for iron homeostasis and their association with poor clinical outcome, we investigated the role of macrophage-secreted iron for tumor progression by applying a novel chelation approach. We applied flow cytometry and multiplex-immunohistochemistry to detect iron-dependent markers and analyzed iron distribution with atomic absorption spectrometry in patients diagnosed with RCC. We further analyzed the functional significance of iron by applying a novel extracellular chelator using RCC cell lines as well as patient-derived primary cells. The expression of iron-regulated genes was significantly elevated in tumors compared to adjacent healthy tissue. Iron retention was detected in tumor cells, whereas tumor-associated macrophages showed an iron-release phenotype accompanied by enhanced expression of ferroportin. We found increased iron amounts in extracellular fluids, which in turn stimulated tumor cell proliferation and migration. In vitro, macrophage-derived iron showed pro-tumor functions, whereas application of an extracellular chelator blocked these effects. Our study provides new insights in iron distribution and iron-handling in RCC. Chelators that specifically scavenge iron in the extracellular space confirmed the importance of macrophage-secreted iron in promoting tumor growth.
    • Improving the Modeling of the Height–Diameter Relationship of Tree Species with High Growth Variability: Robust Regression Analysis of Ochroma pyramidale (Balsa-Tree)

      Zea-Camaño, Jorge Danilo; Soto, José R.; Arce, Julio Eduardo; Pelissari, Allan Libanio; Behling, Alexandre; Orso, Gabriel Agostini; Guachambala, Marcelino Santiago; Eisfeld, Rozane de Loyola; Univ Arizona, Sch Nat Resources & Environm (MDPI, 2020-03-12)
      Ochroma pyramidale (Cav. ex. Lam.) Urb. (balsa-tree) is a commercially important tree species that ranges from Mexico to northern Brazil. Due to its low weight and mechanical endurance, the wood is particularly well-suited for wind turbine blades, sporting equipment, boats and aircrafts; as such, it is in high market demand and plays an important role in many regional economies. This tree species is also well-known to exhibit a high degree of variation in growth. Researchers interested in modeling the height-diameter relationship typically resort to using ordinary least squares (OLS) to fit linear models; however, this method is known to suffer from sensitivity to outliers. Given the latter, the application of these models may yield potentially biased tree height estimates. The use of robust regression with iteratively reweighted least squares (IRLS) has been proposed as an alternative to mitigate the influence of outliers. This study aims to improve the modeling of height-diameter relationships of tree species with high growth variation, by using robust regressions with IRLS for data-sets stratified by site-index and age-classes. We implement a split sample approach to assess the model performance using data from Ecuador's continuous forest inventory (n = 32,279 trees). A sensitivity analysis of six outlier scenarios is also conducted using a subsample of the former (n = 26). Our results indicate that IRLS regression methods can give unbiased height predictions. At face value, the sensitivity analysis indicates that OLS performs better in terms of standard error of estimate. However, we found that OLS suffers from skewed residual distributions (i.e., unreliable estimations); conversely, IRLS seems to be less affected by this source of bias and the fitted parameters indicate lower standard errors. Overall, we recommend using robust regression methods with IRLS to produce consistent height predictions for O. pyramidale and other tree species showing high growth variation.
    • Impact of Self-Assembled Monolayer Design and Electrochemical Factors on Impedance-Based Biosensing

      Brothers, Michael C; Moore, David; St Lawrence, Michael; Harris, Jonathan; Joseph, Ronald M; Ratcliff, Erin; Ruiz, Oscar N; Glavin, Nicholas; Kim, Steve S; Univ Arizona, Dept Chem Engn; et al. (MDPI, 2020-04-16)
      Real-time sensing of proteins, especially in wearable devices, remains a substantial challenge due to the need to convert a binding event into a measurable signal that is compatible with the chosen analytical instrumentation. Impedance spectroscopy enables real-time detection via either measuring electrostatic interactions or electron transfer reactions while simultaneously being amenable to miniaturization for integration into wearable form-factors. To create a more robust methodology for optimizing impedance-based sensors, additional fundamental studies exploring components influencing the design and implementation of these sensors are needed. This investigation addresses a sub-set of these issues by combining optical and electrochemical characterization to validate impedance-based sensor performance as a function of (1) biorecognition element density, (2) self-assembled monolayer chain length, (3) self-assembled monolayer charge density, (4) the electrochemical sensing mechanism and (5) the redox reporter selection. Using a pre-existing lysozyme aptamer and lysozyme analyte combination, we demonstrate a number of design criteria to advance the state-of-the-art in protein sensing. For this model system we demonstrated the following: First, denser self-assembled monolayers yielded substantially improved sensing results. Second, self-assembled monolayer composition, including both thickness and charge density, changed the observed peak position and peak current. Third, single frequency measurements, while less informative, can be optimized to replace multi-frequency measurements and in some cases (such as that with zwitterionic self-assembled monolayers) are preferred. Finally, various redox reporters traditionally not used in impedance sensing should be further explored. Collectively, these results can help limit bottlenecks associated with device development, enabling realization of next-generation impedance-based biosensing with customize sensor design for the specific application.
    • Human Cytomegalovirus Infection Suppresses CD34(+) Progenitor Cell Engraftment in Humanized Mice

      Crawford, Lindsey B; Tempel, Rebecca; Streblow, Daniel N; Yurochko, Andrew D; Goodrum, Felicia D; Nelson, Jay A; Caposio, Patrizia; Univ Arizona, BIO5 Inst, Dept Immunobiol (MDPI, 2020-04-06)
      Human cytomegalovirus (HCMV) infection is a serious complication in hematopoietic stem cell transplant (HSCT) recipients due to virus-induced myelosuppression and impairment of stem cell engraftment. Despite the clear clinical link between myelosuppression and HCMV infection, little is known about the mechanism(s) by which the virus inhibits normal hematopoiesis because of the strict species specificity and the lack of surrogate animal models. In this study, we developed a novel humanized mouse model system that recapitulates the HCMV-mediated engraftment failure after hematopoietic cell transplantation. We observed significant alterations in the hematopoietic populations in peripheral lymphoid tissues following engraftment of a subset of HCMV+ CD34(+) hematopoietic progenitor cells (HPCs) within the transplant, suggesting that a small proportion of HCMV-infected CD34(+) HPCs can profoundly affect HPC differentiation in the bone marrow microenvironment. This model will be instrumental to gain insight into the fundamental mechanisms of HCMV myelosuppression after HSCT and provides a platform to assess novel treatment strategies.
    • Future exacerbation of hot and dry summer monsoon extremes in India

      Mishra, Vimal; Thirumalai, Kaustubh; Singh, Deepti; Aadhar, Saran; Univ Arizona, Dept Geosci (NATURE PUBLISHING GROUP, 2020-03-23)
      Summer monsoon (June-September) precipitation is crucial for agricultural activities in India. Extremes during the monsoon season can have deleterious effects on water availability and agriculture in the region. Here, we show that hot and dry extremes during the summer monsoon season significantly impact food production in India and find that they tend to occur during El Nino years during the observed record of 1951-2018. We then use an ensemble of climate simulations for the historic (1971-2000) and future (2006-2100) that capture this coupling between El Nino and the Indian monsoon to show that the frequency of concurrent hot and dry extremes increases by a factor of 1.5 under continued greenhouse warming during the 21st century. Despite projections of summer monsoon intensification on the order of similar to 10%, the rise in surface air temperatures as well as increase in rainfall variability contributes to more severe hot and dry monsoon extremes over India, thereby posing a substantial challenge to future food security in India.
    • A Toll-receptor map underlies structural brain plasticity

      Li, Guiyi; Forero, Manuel G; Wentzell, Jill S; Durmus, Ilgim; Wolf, Reinhard; Anthoney, Niki C; Parker, Mieczyslaw; Jiang, Ruiying; Hasenauer, Jacob; Strausfeld, Nicholas James; et al. (ELIFE SCIENCES PUBLICATIONS LTD, 2020-02-18)
      Experience alters brain structure, but the underlying mechanism remained unknown. Structural plasticity reveals that brain function is encoded in generative changes to cells that compete with destructive processes driving neurodegeneration. At an adult critical period, experience increases fiber number and brain size in Drosophila. Here, we asked if Toll receptors are involved. Tolls demarcate a map of brain anatomical domains. Focusing on Toll-2, loss of function caused apoptosis, neurite atrophy and impaired behaviour. Toll-2 gain of function and neuronal activity at the critical period increased cell number. Toll-2 induced cycling of adult progenitor cells via a novel pathway, that antagonized MyD88-dependent quiescence, and engaged Weckle and Yorkie downstream. Constant knock-down of multiple Tolls synergistically reduced brain size. Conditional over-expression of Toll-2 and wek at the adult critical period increased brain size. Through their topographic distribution, Toll receptors regulate neuronal number and brain size, modulating structural plasticity in the adult brain.
    • Introducing Spatially Distributed Fire Danger from Earth Observations (FDEO) Using Satellite-Based Data in the Contiguous United States

      Farahmand, Alireza; Stavros, E. Natasha; Reager, John T.; Behrangi, Ali; Univ Arizona, Dept Hydrol & Atmospher Sci (MDPI, 2020-04-16)
      Wildfire danger assessment is essential for operational allocation of fire management resources; with longer lead prediction, the more efficiently can resources be allocated regionally. Traditional studies focus on meteorological forecasts and fire danger index models (e.g., National Fire Danger Rating System-NFDRS) for predicting fire danger. Meteorological forecasts, however, lose accuracy beyond 10 days; as such, there is no quantifiable method for predicting fire danger beyond 10 days. While some recent studies have statistically related hydrologic parameters and past wildfire area burned or occurrence to fire, no study has used these parameters to develop a monthly spatially distributed predictive model in the contiguous United States. Thus, the objective of this study is to introduce Fire Danger from Earth Observations (FDEO), which uses satellite data over the contiguous United States (CONUS) to enable two-month lead time prediction of wildfire danger, a sufficient lead time for planning purposes and relocating resources. In this study, we use satellite observations of land cover type, vapor pressure deficit, surface soil moisture, and the enhanced vegetation index, together with the United States Forest Service (USFS) verified and validated fire database (FPA) to develop spatially gridded probabilistic predictions of fire danger, defined as expected area burned as a deviation from "normal". The results show that the model predicts spatial patterns of fire danger with 52% overall accuracy over the 2004-2013 record, and up to 75% overall accuracy during the fire season. Overall accuracy is defined as number of pixels with correctly predicted fire probability classes divided by the total number of the studied pixels. This overall accuracy is the first quantified result of two-month lead prediction of fire danger and demonstrates the potential utility of using diverse observational data sets for use in operational fire management resource allocation in the CONUS.
    • High-mass X-ray binaries in nearby metal-poor galaxies: on the contribution to nebular He ii emission

      Senchyna, Peter; Stark, Daniel P; Mirocha, Jordan; Reines, Amy E; Charlot, Stéphane; Jones, Tucker; Mulchaey, John S; Univ Arizona, Steward Observ (OXFORD UNIV PRESS, 2020-02-28)
      Despite significant progress both observationally and theoretically, the origin of high-ionization nebular He If emission in galaxies dominated by stellar photoionization remains unclear. Accretion-powered radiation from high-mass X-ray binaries (HMXBs) is still one of the leading proposed explanations for the missing He-ionizing photons, but this scenario has yet to be conclusively tested. In this paper, we present nebular line predictions from a grid of photoionization models with input spectral energy distributions containing the joint contribution of both stellar atmospheres and a multicolour disc model for HMXBs. This grid demonstrates that HMXBs are inefficient producers of the photons necessary to power He II, and can only boost this line substantially in galaxies with HMXB populations large enough to power X-ray luminosities of 10(42) erg s(-1) per unit star formation rate (SFR). To test this, we assemble a sample of 11 low-redshift star-forming galaxies with high-quality constraints on both X-ray emission from Chandra and He II emission from deep optical spectra, including new observations with the MMT. These data reveal that the HMXB populations of these nearby systems are insufficient to account for the observed He It strengths, with typical X-ray luminosities or upper limits thereon of only 10(40)-10(41) erg s(-1) per SFR. This indicates that HMXBs are not the dominant source of He+ ionization in these metal-poor star-forming galaxies. We suggest that the solution may instead reside in revisions to stellar wind predictions, softer X-ray sources, or very hot products of binary evolution at low metallicity.
    • Integration of Pre-intubation Ultrasound into Airway Management Course: A Novel Training Program

      Adhikari, Srikar; Situ-LaCasse, Elaine; Acuña, Josie; Irving, Steven; Weaver, Christina; Samsel, Kara; Biffar, David E; Motlagh, Mahsaw; Sakles, John; Univ Arizona, Dept Emergency Med; et al. (JAYPEE BROTHERS MEDICAL PUBLISHERS PVT LTD, 2020-03-01)
      Objectives: To determine the feasibility of integrating pre-intubation ultrasound into airway course and assess emergency medicine (EM) residents'confidence and comfort level in using ultrasound for pre-intubation hemodynamic stabilization and identifying cricothyroid membrane after the training session. Materials and methods:This is a retrospective study. Pre-intubation ultrasound training was delivered with the following ultrasound components (didactics and hands-on sessions using human models) to EM residents: (1) sonoanatomy and scanning technique to identify cricothyroid membrane and (2) pre-intubation echocardiography for recognition of acute right ventricular failure and pre-intubation hemodynamic stabilization. Results: A total of 56 EM residents participated In this study. Only 21% [95% confidence interval (CI), 10-31%] reported using ultrasound for pre-intubation hemodynamic stabilization. After the training session, 89% (95% CI, 81-97%) reported that ultrasound-based teaching increased their knowledge of pre-intubation hemodynamic stabilization compared with traditional teaching methods. On a scale of 1 (low) through 10 (high), the average comfort level for integrating ultrasound findings into medical decision making for pre-intubation hemodynamic stabilization was 6.8 (95% CI, 6.3-7.3). Seventy-nine percent (95% CI, 68-89%) reported that focused training in airway ultrasound is adequate to identify cricothyroid membrane. On a scale of 1 (low) through 10 (high), the average confidence level for identifying cricothyroid membrane using ultrasound was 6.6 (95% CI, 6.1-7.1). Conclusion: At our institution, we successfully integrated pre-intubation ultrasound into an airway course. Emergency medicine residents had a moderate level of comfort and confidence level using ultrasound for pre-intubation hemodynamic stabilization and identifying cricothyroid membrane after the training session.
    • Global Trends in Evapotranspiration Dominated by Increases across Large Cropland Regions

      Javadian, Mostafa; Behrangi, Ali; Smith, William Kolby; Fisher, Joshua B.; Univ Arizona, Dept Hydrol & Atmospher Sci; Univ Arizona, Sch Nat Resources & Environm (MDPI, 2020-04-10)
      Irrigated croplands require large annual water inputs and are critical to global food production. Actual evapotranspiration (AET) is a main index of water use in croplands, and several remote-sensing products have been developed to quantify AET at the global scale. In this study, we estimate global trends in actual AET, potential ET (PET), and precipitation rate (PP) utilizing the MODIS Evapotranspiration product (2001-2018) within the Google Earth Engine cloud-computing environment. We then introduce a new index based on a combination of AET, PET, and PP estimates-the evapotranspiration warning index (ETWI)-which we use to evaluate the sustainability of observed AET trends. We show that while AET has not considerably changed across global natural lands, it has significantly increased across global croplands (+14% +/- 5%). The average ETWI for global croplands is -0.40 +/- 0.25, which is largely driven by an extreme trend in AET, exceeding both PET and PP trends. Furthermore, the trends in water and energy limited areas demonstrate, on a global scale, while AET and PET do not have significant trends in both water and energy limited areas, the increasing trend of PP in energy-limited areas is more than water-limited areas. Averaging cropland ETWI trends at the country level further revealed nonsustainable trends in cropland water consumptions in Thailand, Brazil, and China. These regions were also found to experiencing some of the largest increases in net primary production (NPP) and solar-induced fluorescence (SIF), suggesting that recent increases in food production may be dependent on unsustainable water inputs. Globally, irrigated maize was found to be associated with nonsustainable AET trends relative to other crop types. We present an online open access application designed to enable near real-time monitoring and improve the understanding of global water consumption and availability.
    • Development of Cross-Domain Artificial Neural Network to Predict High-Temporal Resolution Pressure Data

      Choi, Young Hwan; Jung, Donghwi; Univ Arizona, Dept Civil & Architectural Engn & Mech (MDPI, 2020-05-08)
      Forecasting hydraulic data such as pressure and demand in water distribution system (WDS) is an important task that helps ensure efficient and accurate operations. Despite high-performance data prediction, missing data can still occur, making it difficult to effectively operate WDS. Though the pressure data are directly related to the rules of operation for pumps or valves, few studies have been conducted on pressure data forecasting. This study proposes a new missing and incomplete data control approach based on real pressure data for reliable and efficient WDS operation and maintenance. The proposed approach is: (1) application of source data from high-resolution, real-world pressure data; (2) development of a cross-domain artificial neural network (CDANN), combining the standard artificial neural networks (ANNs) and the cross-domain training approach for missing data control; and (3) analysis of standard data mining according to external factors to improve prediction accuracy. To verify the proposed approach, a real-world network located in South Korea was used, and the forecasting results were evaluated through performance indicators (i.e., overall, special points, and percentage errors). The performance of the CDANN is compared with that of standard ANNs, and CDANN was found to provide better predictions than traditional ANNs.
    • A Novel Divergent Geminivirus Identified in Asymptomatic New World Cactaceae Plants

      Fontenele, Rafaela S; Salywon, Andrew M; Majure, Lucas C; Cobb, Ilaria N; Bhaskara, Amulya; Avalos-Calleros, Jesús A; Argüello-Astorga, Gerardo R; Schmidlin, Kara; Khalifeh, Anthony; Smith, Kendal; et al. (MDPI, 2020-04-03)
      Cactaceae comprise a diverse and iconic group of flowering plants which are almost exclusively indigenous to the New World. The wide variety of growth forms found amongst the cacti have led to the trafficking of many species throughout the world as ornamentals. Despite the evolution and physiological properties of these plants having been extensively studied, little research has focused on cactus-associated viral communities. While only single-stranded RNA viruses had ever been reported in cacti, here we report the discovery of cactus-infecting single-stranded DNA viruses. These viruses all apparently belong to a single divergent species of the family Geminiviridae and have been tentatively named Opuntia virus 1 (OpV1). A total of 79 apparently complete OpV1 genomes were recovered from 31 different cactus plants (belonging to 20 different cactus species from both the Cactoideae and Opuntioideae clades) and from nine cactus-feeding cochineal insects (Dactylopius sp.) sampled in the USA and Mexico. These 79 OpV1 genomes all share > 78.4% nucleotide identity with one another and < 64.9% identity with previously characterized geminiviruses. Collectively, the OpV1 genomes display evidence of frequent recombination, with some genomes displaying up to five recombinant regions. In one case, recombinant regions span similar to 40% of the genome. We demonstrate that an infectious clone of an OpV1 genome can replicate in Nicotiana benthamiana and Opuntia microdasys. In addition to expanding the inventory of viruses that are known to infect cacti, the OpV1 group is so distantly related to other known geminiviruses that it likely represents a new geminivirus genus. It remains to be determined whether, like its cactus hosts, its geographical distribution spans the globe.
    • A Complex of Badnavirus Species Infecting Cacao Reveals Mixed Infections, Extensive Genomic Variability, and Interspecific Recombination

      Ramos-Sobrinho, Roberto; Chingandu, Nomatter; A Gutierrez, Osman; Marelli, Jean-Philippe; K Brown, Judith; Univ Arizona, Sch Plant Sci (MDPI, 2020-04-14)
      The incidence of cacao swollen shoot disease (CSSD) in cacao (Theobroma cacao L.) has increased in West Africa since similar to 2000. To investigate the genomic and species diversity of the CSSD-badnaviruses infecting cacao in Cote d'Ivoire and Ghana, symptomatic leaves were subjected to high-throughput sequencing. Among the 30 newly determined genomes, three badnaviruses were identified, Cacao swollen shoot Togo B virus (CSSTBV), Cacao swollen shoot CD virus, and Cacao swollen shoot CE virus (CSSCEV). The phylogenetic trees reconstructed for the reverse transcriptase (RT) and ribonuclease H (RNase H) sequences were incongruent with the complete viral genomes, which had the most robust statistical support. Recombination seems to be involved in the CSSD-badnavirus diversification. The genomic diversity varied among different CSSD-badnaviruses, with CSSTBV showing the lowest nucleotide diversity (pi = 0.06236), and CSSCEV exhibiting the greatest variability (pi = 0.21911). Evidence of strong purifying selection was found in the coding regions of the CSSTBV isolates.
    • Modulation of Broadband Emissions in Two-Dimensional ⟨100⟩-Oriented Ruddlesden–Popper Hybrid Perovskites

      Yin, Jun; Naphade, Rounak; Gutiérrez Arzaluz, Luis; Brédas, Jean-Luc; Bakr, Osman M.; Mohammed, Omar F.; Univ Arizona, Dept Chem & Biochem (AMER CHEMICAL SOC, 2020-05-28)
      Two-dimensional (2D) Ruddlesden–Popper (RP) perovskites are emerging materials for light-emitting applications. Unfortunately, their desirable narrowband emission coexists with broadband emissions, which limits the color quality and performance of the light source. However, the origin of such broadband emission in ⟨100⟩-oriented perovskites is still under debate. Here, we experimentally and theoretically demonstrate that unlike ⟨110⟩-oriented RP perovskites, the broadband emission of the 2D ⟨100⟩-oriented RP (PEA)2PbI4 (PEA = C6H5C2H4NH3+) perovskites originates from defect-related luminescence centers. We find that the broadband emission of this prototype 2D structure can be largely suppressed by using excess PEAI treatment. Density functional theory (DFT) calculations indicate that iodine (I) vacancies both in the bulk and on the surface are responsible for the broadband emission. We attribute the decreased broadband emission after PEAI treatment to the passivation of both undercoordinated Pb2+ ions on the surface and I vacancies in the bulk through I– ion migration.
    • Genetic Admixture and Survival in Diverse Populations with Pulmonary Arterial Hypertension

      Karnes, Jason H; Wiener, Howard W; Schwantes-An, Tae-Hwi; Natarajan, Balaji; Sweatt, Andrew J; Chaturvedi, Abhishek; Arora, Amit; Batai, Ken; Nair, Vineet; Steiner, Heidi E; et al. (AMER THORACIC SOC, 2020-01-09)
      Rationale: Limited information is available on racial/ethnic differences in pulmonary arterial hypertension (PAH). Objectives: Determine effects of race/ethnicity and ancestry on mortality and disease outcomes in diverse patients with PAH. Methods: Patients with Group 1 PAH were included from two national registries with genome-wide data and two local cohorts, and further incorporated in a global meta-analysis. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for transplant-free, all-cause mortality in Hispanic patients with non-Hispanic white (NHW) patients as the reference group. Odds ratios (ORs) for inpatient-specific mortality in patients with PAH were also calculated for race/ethnic groups from an additional National Inpatient Sample dataset not included in the meta-analysis. Measurements and Main Results: After covariate adjustment, self-reported Hispanic patients (n = 290) exhibited significantly reduced mortality versus NHW patients (n = 1,970) after global meta-analysis (HR, 0.60 [95% CI, 0.41-0.87]; P = 0.008). Although not significant, increasing Native American genetic ancestry appeared to account for part of the observed mortality benefit (HR, 0.48 [95% CI, 0.23-1.01]; P= 0.053) in the two national registries. Finally, in the National Inpatient Sample, an inpatient mortality benefit was also observed for Hispanic patients (n = 1,524) versus NHW patients (n = 8,829; OR, 0.65 [95% CI, 0.50-0.84]; P = 0.001). An inpatient mortality benefit was observed for Native American patients (n = 185; OR, 0.38 [95% CI, 0.15-0.93]; P= 0.034). Conclusions: This study demonstrates a reproducible survival benefit for Hispanic patients with Group 1 PAH in multiple clinical settings. Our results implicate contributions of genetic ancestry to differential survival in PAH.
    • The lived experience of linear algebra: a counter-story about women of color in mathematics

      Adiredja, Aditya P.; Zandieh, Michelle; Univ Arizona, Fac Math (SPRINGER, 2020-06-06)
      This paper focuses on the mathematical sensemaking by women of color in the USA as part of the global effort of dismantling deficit narratives about historically marginalized groups of students. Following Adiredja's anti-deficit framework for sensemaking, this cognitive study invited a group of women of color to share their understanding of basis from linear algebra to construct a sensemaking counter-story. Extending the framework, this study examines a task that explores the boundaries and nuances of a concept to support the effort of going beyond students' deficits. Eight women extended the concept of basis (and vector spaces) to 22 distinct everyday contexts, drawing from their everyday lives as well as topics from their academic experiences. Their explanations revealed analytical codes describing roles and characteristics of a basis. These codes suggest ways that students can mobilize the concept of basis beyond its logical underpinnings. Contrasting interpretations using a deficit and an anti-deficit perspective construct a counter-story that showcases these women's creativity and flexibility in understanding the concept, and potential resources for the teaching and learning of linear algebra.
    • Chromosome-level hybrid de novo genome assemblies as an attainable option for nonmodel insects

      Jaworski, Coline C; Allan, Carson W; Matzkin, Luciano M; Univ Arizona, Dept Entomol; Univ Arizona, BIO5 Inst; Univ Arizona, Dept Ecol & Evolutionary Biol (WILEY, 2020-04-23)
      The emergence of third-generation sequencing (3GS; long-reads) is bringing closer the goal of chromosome-size fragments in de novo genome assemblies. This allows the exploration of new and broader questions on genome evolution for a number of nonmodel organisms. However, long-read technologies result in higher sequencing error rates and therefore impose an elevated cost of sufficient coverage to achieve high enough quality. In this context, hybrid assemblies, combining short-reads and long-reads, provide an alternative efficient and cost-effective approach to generate de novo, chromosome-level genome assemblies. The array of available software programs for hybrid genome assembly, sequence correction and manipulation are constantly being expanded and improved. This makes it difficult for nonexperts to find efficient, fast and tractable computational solutions for genome assembly, especially in the case of nonmodel organisms lacking a reference genome or one from a closely related species. In this study, we review and test the most recent pipelines for hybrid assemblies, comparing the model organism Drosophila melanogaster to a nonmodel cactophilic Drosophila, D. mojavensis. We show that it is possible to achieve excellent contiguity on this nonmodel organism using the dbg2olc pipeline.
    • Boosting Self-Trapped Emissions in Zero-Dimensional Perovskite Heterostructures

      Yin, Jun; Brédas, Jean-Luc; Bakr, Osman M.; Mohammed, Omar F.; Univ Arizona, Dept Chem & Biochem (AMER CHEMICAL SOC, 2020-05-22)
      Zero-dimensional (0D) inorganic perovskites have attracted great interest for white-light-emitting applications because of their broad band emissions originating from self-trapped excitons. In this work, we explore and decipher exciton self-trapping in a series of 0D inorganic perovskites, A4PbX6 and A4SnX6 (A = K, Rb, and Cs; X = Cl, Br, and I) at the density functional theory level within the theoretical framework of the one-dimensional configuration coordinate diagram. We demonstrate that the formation of self-trapped states in A4PbX6 and A4SnX6 can be attributed to local structural distortions of individual [PbX6]4– and [SnX6]4– octahedra. Importantly, with the goal of both potentially improving the stability of the Sn derivatives and enhancing the emission efficiency, we further propose and design two types of 0D perovskite heterostructures, bulk A4PbX6/A4SnX6 mixtures and A4PbX6/A4SnX6 heterojunctions. We find that these 0D heterostructures exhibit type-I energy level alignment in which energy transfer from A4PbX6 to A4SnX6 is strongly promoted. Interestingly, these heterostructures show an increase in the transition dipole moments between the ground and self-trapped states compared to the pristine 0D perovskites. Our findings provide a new material design strategy for boosting self-trapped emissions with improved air stability for white-light-emitting applications.