Now showing items 12820-12839 of 14021

    • The dependence of the hierarchical distribution of star clusters on galactic environment

      Menon, S.H.; Grasha, K.; Elmegreen, B.G.; Federrath, C.; Krumholz, M.R.; Calzetti, D.; Sánchez, N.; Linden, S.T.; Adamo, A.; Messa, M.; et al. (Oxford University Press, 2021)
      We use the angular two-point correlation function (TPCF) to investigate the hierarchical distribution of young star clusters in 12 local (3-18 Mpc) star-forming galaxies using star cluster catalogs obtained with the Hubble Space Telescope (HST) as part of the Treasury Program Legacy ExtraGalactic UV Survey. The sample spans a range of different morphological types, allowing us to infer how the physical properties of the galaxy affect the spatial distribution of the clusters. We also prepare a range of physically motivated toy models to compare with and interpret the observed features in the TPCFs. We find that, conforming to earlier studies, young clusters ($T \lesssim 10\, \mathrm{Myr}$) have power-law TPCFs that are characteristic of fractal distributions with a fractal dimension D2, and this scale-free nature extends out to a maximum scale lcorr beyond which the distribution becomes Poissonian. However, lcorr, and D2 vary significantly across the sample, and are correlated with a number of host galaxy physical properties, suggesting that there are physical differences in the underlying star cluster distributions. We also find that hierarchical structuring weakens with age, evidenced by flatter TPCFs for older clusters ($T \gtrsim 10\, \mathrm{Myr}$), that eventually converges to the residual correlation expected from a completely random large-scale radial distribution of clusters in the galaxy in $\sim 100 \, \mathrm{Myr}$. Our study demonstrates that the hierarchical distribution of star clusters evolves with age, and is strongly dependent on the properties of the host galaxy environment. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
    • The Detection of Ionized Carbon Emission at z ∼ 8

      Topping, M.W.; Shapley, A.E.; Stark, D.P.; Endsley, R.; Robertson, B.; Greene, J.E.; Furlanetto, S.R.; Tang, M.; Steward Observatory, University of Arizona (American Astronomical Society, 2021)
      We present deep Keck/MOSFIRE H-band spectroscopic observations covering the [C iii],C iii]λλ1907, 1909 doublet for three z ∼ 8 galaxy candidates in the AEGIS field. Along with nondetections in two galaxies, we obtain one of the highest-redshift detections to date of [C iii]λ1907 for the galaxy AEGIS-33376, finding z spec = 7.945 0.001. We measure a [C iii]λ1907 flux of 2.24 0.71 10-18erg s-1cm-2, corresponding to a rest-frame equivalent width of 20.3 6.5 Å for the single line. Given the not very constraining upper limit for C iii]λ1909 based on strong sky-line contamination, we assume a [C iii]λ1907/C iii]λ1909 doublet ratio of 1.5 and infer a total [C iii][C iii]λλ1907, 1909 equivalent width of 33.7 10.8 Å. We repeat the same reductions and analysis on multiple subsets of our raw data divided on the basis of time and observing conditions, verifying that the [C iii]λ1907 emission is present for AEGIS-33376 throughout our observations. We also confirm that the significance of the [C iii]λ1907 detection in different subsets of our data tracks that of brighter emission features detected on the same multi-slit mask. These multiple tests suggest that the observed emission line is real and associated with the z ∼ 8 target. The strong observed [C iii],C iii]λλ1907, 1909 in AEGIS-33376 likely indicates ISM conditions of low metallicity, high ionization parameter, and a hard ionizing spectrum, although AGN contributions are possible. This single detection represents a sizable increase in the current sample [C iii],C iii]λλ1907, 1909 detections at z > 7, while JWST will provide the first statistical samples of such measurements at these redshifts. © 2021. The American Astronomical Society. All rights reserved..
    • The development of autonomous student learning networks: Patterns of interactions in an open world learning environment for teachers exploring teaching with and through computer science

      Ardito, G.; Czerkawski, B.; Department of Applied Technology, The University of Arizona (MDPI AG, 2021)
      This pilot case study sought to investigate patterns of interactions between learners and their instructor in a teacher education course called “Computer Science for Teachers”. This course was constructed to leverage aspects of open world game design elements in order to investigate the effects of degrees of autonomy in gameplay/learning. This course was conducted in a specially built social learning platform based on Elgg software. Student interactions with the instructor and other students in this course were analyzed to determine the learning networks students constructed during each key learning activity as well as the epistemic spaces defined by these interactions. Descriptive statistics along with social network analysis (SNA) and epistemic network analysis (ENA) were used to investigate these data. The findings indicate that more traditional/less open world gaming type learning activities were associated with learning networks and epistemic spaces that were teacher-centered and narrower, while more open world gaming/high levels of autonomy (student-centric) learning activities were associated with learning networks that were highly decentralized and epistemic spaces that featured students asking and answering questions of/for one another. These findings were consistent with existing research into player behavior in open world type games and learner behavior in settings with high levels of autonomy support. Implications for further research are discussed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
    • ‘The Devil’s Company’: A Grounded Theory Study on Aging, Loneliness and Social Change Among ‘Older Adult Children’ in Rural Indonesia

      Schröders, J.; Nichter, M.; San Sebastian, M.; Nilsson, M.; Dewi, F.S.T.; School of Anthropology, College of Social and Behavioral Sciences, The University of Arizona (Frontiers Media S.A., 2021)
      Introduction: As a consequence of rising life expectancies, many families are no longer made up of one, but two simultaneously aging generations. This elderly parent–older adult child (OAC) dyad has emerged as a newly overserved yet little explored demographic phenomenon. Studies on this intergenerational aging dyad and the possible ramifications of when caregivers are simultaneously aging with care-receivers are scarce, especially in low and middle-income countries. This study explored the process by which rural Indonesian OACs experience their own aging, thereby gaining insights into how this newly evolving reality impacts the traditional ways of old-age care provision. Methods: This study has a qualitative design and draws on eight focus group discussions with 48 community-dwelling OACs (23 men, 25 women; mean age 64 years) in four rural villages in the Yogyakarta Special Region, Indonesia. The theoretical framework was largely inspired by symbolic interactionism aided by the sensitizing concepts of social network deficits, interpersonal emotions, and the social construction of risks. Data were analyzed using Grounded Theory as outlined by Corbin and Strauss. Results: Respondents’ accounts reflected four categories: 1) aging in a welt of chronic insecurity; 2) OACs: a generation “betwixt and between” expected demands and unmet expectations; 3) landscapes of loneliness; and 4) compromising against conventions. As depicted in a conceptual model, these categories interrelated with each other and were linked by a core category, “bargaining for a sense of security”, which collectively summarized a process by which OACs’ experienced their own course of aging. Conclusion: Our study provided insights into how and why loneliness emerged amidst the challenges of social and demographic transformations and how in response to this unconventional compromises were made, which affect both the networks of caretakers and the places of old-age care. It is doing so by including the perspectives of rural Indonesian OACs. The results showed how multiple intersecting negative experiences constrained the aging experiences of OACs and produced precarious aging trajectories. Our findings highlight the importance of old-age loneliness as an emerging public health and social problem by discussing how intrinsically this emotion was interwoven with social life. © Copyright © 2021 Schröders, Nichter, San Sebastian, Nilsson and Dewi.
    • The Difference between Plan b and ella (R)? They're Basically the Same Thing: Results from a Mystery Client Study

      Kaur, Guneet; Fontanilla, Tiana; Bullock, Holly; Tschann, Mary; Univ Arizona, Dept Obstet & Gynecol (MDPI, 2020-06)
      Pharmacy staff can serve an important role educating patients about emergency contraceptive pills (ECP), particularly ulipristal acetate (UPA), which requires a prescription. We conducted a secondary analysis of a previously completed mystery client study, assessing accuracy of information provided by pharmacy staffers to patients inquiring by telephone about filling a prescription for UPA. From the period December 2013 to July 2014, researchers used a mystery client methodology, contacting 198 retail pharmacies in HawaiModified Letter Turned Commai. Researchers posed as patients or providers attempting to fill a prescription for UPA. During the course of the call, they asked about differences between UPA and levonorgestrel ECPs. Nearly half of all pharmacy staffers were unfamiliar with UPA. The majority of responses describing differences between the medications were incorrect or misleading, such as responses implying that UPA is an abortifacient. Lack of familiarity and incorrect information provided by pharmacy staffers may act as additional barriers in patient access to UPA. Health practitioners prescribing UPA should ensure patients receive evidence-based counseling at the time of prescription, while efforts should also be made to improve pharmacy staff familiarity with emergency contraceptive options.
    • The Discovery of a Highly Accreting, Radio-loud Quasar at z = 6.82

      Bantados, E.; Mazzucchelli, C.; Momjian, E.; Eilers, A.-C.; Wang, F.; Schindler, J.-T.; Connor, T.; Andika, I.T.; Barth, A.J.; Carilli, C.; et al. (IOP Publishing Ltd, 2021)
      Radio sources at the highest redshifts can provide unique information on the first massive galaxies and black holes, the densest primordial environments, and the epoch of reionization. The number of astronomical objects identified at z > 6 has increased dramatically over the last few years, but previously only three radio-loud (R 2500 = f ν,5 GHz/f ν,2500 Å > 10) sources had been reported at z > 6, with the most distant being a quasar at z = 6.18. Here we present the discovery and characterization of PSO J172.3556+18.7734, a radio-loud quasar at z = 6.823. This source has an Mg ii-based black hole mass of ∼3 × 108 M o˙ and is one of the fastest accreting quasars, consistent with super-Eddington accretion. The ionized region around the quasar is among the largest measured at these redshifts, implying an active phase longer than the average lifetime of the z ⪆ 6 quasar population. From archival data, there is evidence that its 1.4 GHz emission has decreased by a factor of two over the last two decades. The quasar's radio spectrum between 1.4 and 3.0 GHz is steep (α = -1.31). Assuming the measured radio slope and extrapolating to rest-frame 5 GHz, the quasar has a radio-loudness parameter R 2500 ∼ 90. A second steep radio source (α = -0.83) of comparable brightness to the quasar is only 23.″1 away (∼120 kpc at z = 6.82; projection probability <2%), but shows no optical or near-infrared counterpart. Further follow-up is required to establish whether these two sources are physically associated. © 2021. The Author(s). Published by the American Astronomical Society..
    • The diverse lives of progenitors of hydrogen-rich core-collapse supernovae: The role of binary interaction

      Zapartas, E.; De Mink, S.E.; Justham, S.; Smith, N.; De Koter, A.; Renzo, M.; Arcavi, I.; Farmer, R.; Götberg, Y.; Toonen, S.; et al. (EDP Sciences, 2019)
      Hydrogen-rich supernovae, known as Type II (SNe II), are the most common class of explosions observed following the collapse of the core of massive stars. We used analytical estimates and population synthesis simulations to assess the fraction of SNe II progenitors that are expected to have exchanged mass with a companion prior to explosion. We estimate that 1/3 to 1/2 of SN II progenitors have a history of mass exchange with a binary companion before exploding. The dominant binary channels leading to SN II progenitors involve the merger of binary stars. Mergers are expected to produce a diversity of SN II progenitor characteristics, depending on the evolutionary timing and properties of the merger. Alternatively, SN II progenitors from interacting binaries may have accreted mass from their companion, and subsequently been ejected from the binary system after their companion exploded. We show that the overall fraction of SN II progenitors that are predicted to have experienced binary interaction is robust against the main physical uncertainties in our models. However, the relative importance of different binary evolutionary channels is affected by changing physical assumptions. We further discuss ways in which binarity might contribute to the observed diversity of SNe II by considering potential observational signatures arising from each binary channel. For supernovae which have a substantial H-rich envelope at explosion (i.e., excluding Type IIb SNe), a surviving non-compact companion would typically indicate that the supernova progenitor star was in a wide, non-interacting binary. We argue that a significant fraction of even Type II-P SNe are expected to have gained mass from a companion prior to explosion. © ESO 2018.
    • The Dusty Heart of NGC 4151 Revealed by λ ∼ 1-40 μm Reverberation Mapping and Variability: A Challenge to Current Clumpy Torus Models

      Lyu, J.; Rieke, G.H.; Steward Observatory, University of Arizona (IOP Publishing Ltd, 2021)
      We probe the dusty environment of the archetypical Type 1 active galactic nucleus (AGN) in NGC 4151 with comprehensive IR reverberation mapping over several decades, in the J (∼1.22 μm), H (∼1.63 μm), K (∼2.19 μm), L (∼3.45 μm), and N bands (∼10.6 μm), plus multiple measurements at 20-40 μm. At 1-4 μm, the hot dust reverberation signals come from two distinct dust populations at separate radii (∼0.033 pc and ∼0.076 pc), with temperatures of ∼1500-2500 K and ∼900-1000 K, consistent with the expected properties of sublimating graphite and silicate dust grains. The domination of the torus infrared output by carbon and silicate grains near their sublimation temperatures and radii may account for the general similarity of AGN near-IR spectral energy distributions. The torus inner edge defined by the hottest dust remains at roughly the same radius independent of the AGN optical luminosity over ∼25 yr. The emission by hot dust warmed directly by the optical/UV AGN output has increased gradually by ∼4% yr-1, indicating a possibly growing torus. A third dust component at ∼700 K does not seem to participate directly in the IR reverberation behavior, and its emission may originate deep in the circumnuclear torus. We find a reverberation signal at ∼10 μm with an inferred radius for the warm dust of ∼2.2-3.1 pc. The lack of variability at 20-40 μm indicates that the far-IR emission comes from even more extended regions. The torus properties revealed by dust reverberation analysis are inconsistent with predictions from pure clumpy torus models. Instead, the longer-wavelength emission possibly originates in a flared torus or the polar wind. © 2021. The American Astronomical Society. All rights reserved..
    • The effect of anthropogenic aerosols on the aleutian low

      Dow, W.J.; Maycock, A.C.; Lofverstrom, M.; Smith, C.J.; Department of Geosciences, University of Arizona (American Meteorological Society, 2021)
      Past studies have suggested that regional trends in anthropogenic aerosols can influence the Pacific decadal oscillation (PDO) through modulation of the Aleutian low. However, the robustness of this connection is debated. This study analyzes changes to the Aleutian low in an ensemble of climate models forced with large, idealized global and regional black carbon (BC) and sulfate aerosol perturbations. To isolate the role of ocean feedbacks, the experiments are performed with an interactive ocean and with prescribed sea surface temperatures. The results show a robust weakening of the Aleutian low forced by a global tenfold increase in BC in both experiment configurations. A linearized steady-state primitive equation model is forced with diabatic heating anomalies to investigate the mechanisms through which heating from BC emissions influences the Aleutian low. The heating from BC absorption over India and East Asia generates Rossby wave trains that propagate into the North Pacific sector, forming an upper-tropospheric ridge. Sources of BC outside of East Asia enhance the weakening of the Aleutian low. The responses to a global fivefold and regional tenfold increase in sulfate aerosols over Asia show poor consistency across climate models, with a multimodel mean response that does not project strongly onto the Aleutian low. These findings for a large, idealized step increase in regional sulfate aerosol differ from previous studies that suggest the transient increase in sulfate aerosols over Asia during the early twenty-first century weakened the Aleutian low and induced a transition to a negative PDO phase. © 2021 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (
    • The Effect of Head Rotation on the Relative Vascular Anatomy of the Neck: Implications for Central Venous Access

      Merritt, Raymond L.; Hachadorian, Michael E.; Michaels, Kristof; Zevallos, Eric; Mhayamaguru, Kubwimana M.; Closser, Zuheily; Derr, Charlotte; Univ Arizona, Banner Univ Med Ctr (WOLTERS KLUWER MEDKNOW PUBLICATIONS, 2018)
      Context: Previous studies have shown that safe venous cannulation is difficult when the internal jugular vein (IJV) overlies the carotid artery (CA) as the probability of inadvertent arterial penetration is greatly increased. Aims: The goal of this study was to examine the anatomical relationships of the IJV and CA as a function of the degree of head rotation in order to minimize the risk for CA puncture. Settings and Design: Our study was a prospective study using a sample of 496 Emergency Department patients. Methods and Material: The anatomic relationships of the right and left IJVs and CAs were recorded with head rotation at three different positions. Patients who had the IJV in a 45 to 135 degree relationship to the CA were deemed to be in the high-risk zone for arterial puncture. Statistical Analysis: Chi square, ANOVA. Results: Right IJVs were in the high risk zone for 39.5%, 47.8% and 60.9% of cases at 0, 45 and 80 degrees of head rotation, respectively (P < 0.001). Left IJVs were in the high risk zone for 59.1%, 69.2% and 80.0% at 0, 45 and 80 degrees of head rotation, respectively. (P < 0.001). Conclusions: Head rotation should be minimized during IJV cannulation to decrease the overlap of CA by IN Cannulation of the left IN appears to carry a higher degree of risk as compared to the right IJV. Placing the head in neutral position, avoiding rotation, and using ultrasound guidance are recommended to minimize complications during central venous access.
    • The effect of inefficient accretion on planetary differentiation

      Cambioni, S.; Jacobson, S.A.; Emsenhuber, A.; Asphaug, E.; Rubie, D.C.; Gabriel, T.S.J.; Schwartz, S.R.; Furfaro, R.; Lunar and Planetary Laboratory, University of Arizona; Department of Systems and Industrial Engineering, Department of Aerospace and Mechanical Engineering, University of Arizona (IOP Publishing, 2021)
      Pairwise collisions between terrestrial embryos are the dominant means of accretion during the last stage of planet formation. Hence, their realistic treatment in N-body studies is critical to accurately model the formation of terrestrial planets and to develop interpretations of telescopic and spacecraft observations. In this work, we compare the effects of two collision prescriptions on the core-mantle differentiation of terrestrial planets: A model in which collisions are always completely accretionary ("perfect merging"), and a more realistic model based on neural networks that has been trained on hydrodynamical simulations of giant impacts. The latter model is able to predict the loss of mass due to imperfect accretion and the evolution of nonaccreted projectiles in hit-and-run collisions. We find that the results of the neural network model feature a wider range of final core mass fractions and metal-silicate equilibration pressures, temperatures, and oxygen fugacities than the assumption of perfect merging. When used to model collisions in N-body studies of terrestrial planet formation, the two models provide similar answers for planets more massive than ≈0.1M⊕ (Earth masses). For less massive final bodies, however, the inefficient-accretion model predicts a higher degree of compositional diversity. This phenomenon is not reflected in planet formation models of the solar system that use perfect merging to determine collisional outcomes. Our findings confirm the role of giant impacts as important drivers of planetary diversity and encourage a realistic implementation of inefficient accretion in future accretion studies. © 2021 The Author(s).
    • The Effect of Resolution on Vertical Heat and Carbon Transports in a Regional Ocean Circulation Model of the Argentine Basin

      Swierczek, S.; Mazloff, M.R.; Morzfeld, M.; Russell, J.L.; Program in Applied Mathematics, University of Arizona; Department of Geosciences, University of Arizona (John Wiley and Sons Inc, 2021)
      Simulations of the Argentine Basin have large uncertainties associated with quantities such as air-sea exchanges of heat and carbon in current generation climate models and ocean reanalysis products. This is due to the complex topography, profound undersampling until recent years, and strong currents and mixing of subpolar and subtropical water masses in the basin. Because mixing of water masses is important here, model resolution is hypothesized to play an important role in estimating ocean quantities and determining overall budgets. We construct three regional ocean models with biogeochemistry at 1/3°, 1/6°, and 1/12° resolutions for the year 2017 to investigate heat and carbon dynamics in the region and determine the effect of model resolution on these dynamics. Initial conditions and boundary forcing from BSOSE (the Biogeochemical Southern Ocean State Estimate (Verdy & Mazloff, 2017), and atmospheric forcing from ERA5 are used. The models are evaluated for accuracy by comparing output to Argo and BGC-Argo float profiles, BSOSE, and other reanalyses and mapped products. We then quantify the effect of resolution on model upper ocean heat and carbon transport and the associated air-sea exchanges. We determine that increasing the resolution from 1/3° to 1/12° enhances the upward vertical transport and surface exchanges of heat but causes no significant effect on surface carbon fluxes despite enhancing downward transport of anomalous DIC. © 2021. American Geophysical Union. All Rights Reserved.
    • The effects of naloxone, diazepam, and quercetin on seizure and sedation in acute on chronic tramadol administration: an experimental study

      Nakhaee, S.; Farrokhfall, K.; Miri-Moghaddam, E.; Foadoddini, M.; Askari, M.; Amirabadizadeh, A.; Brent, J.; Megarbane, B.; Mehrpour, O.; Mel and Enid Zuckerman College of Public Health, University of Arizona (BioMed Central Ltd, 2021)
      Background: Tramadol is a widely used synthetic opioid. Substantial research has previously focused on the neurological effects of this drug, while the efficacy of various treatments to reduce the associated side effects has not been well studied. This study aimed to evaluate the protective effects of naloxone, diazepam, and quercetin on tramadol overdose-induced seizure and sedation level in male rats. Methods: The project was performed with 72 male Wistar rats with an average weight of 200–250 g. The rats were randomly assigned to eight groups. Tramadol was administered intraperitoneally at an initial dose of 25 mg/kg/day. On the 14th day, tramadol was injected at 75 mg/kg, either alone or together with naloxone, diazepam, and quercetin (acute and chronic) individually or in combination. The rats were monitored for 6 h on the last day, and the number, the duration, and the severity of seizures (using the criteria of Racine) were measured over a 6-h observation period. The sedation level was also assessed based on a 4-point criterion, ranging from 0 to 3. Data were analyzed in SPSS software using Kruskal–Wallis, Chi-square, regression analysis, and generalized estimating equation (GEE) tests. The significance level was set at P < 0.05. Results: The naloxone-diazepam combination reduced the number, severity, and cumulative duration of seizures compared to tramadol use alone and reduced the number of higher-intensity seizures (level 3, 4) to a greater extent than other treatments. Naloxone alone reduced the number and duration of seizures but increased the number of mild seizures (level 2). Diazepam decreased the severity and duration of seizures. However, it increased the number of mild seizures (level 2). In comparison with the tramadol alone group, the acute quercetin group exhibited higher numbers of mild (level 2) and moderate (level 3) seizures. Chronic quercetin administration significantly increased the number of mild seizures. In the GEE model, all groups had higher sedation levels than the saline only group (P < 0.001). None of the protocols had a significant effect on sedation levels compared to the tramadol group. Conclusion: The combined administration of naloxone and diazepam in acute-on-chronic tramadol poisoning can effectively reduce most seizure variables compared to tramadol use alone. However, none of the treatments improved sedation levels. © 2021, The Author(s).
    • The effects of quercetin on seizure, inflammation parameters and oxidative stress in acute on chronic tramadol intoxication

      Nakhaee, S.; Farrokhfall, K.; Miri-Moghaddam, E.; Foadoddini, M.; Askari, M.; Mehrpour, O.; Mel and Enid Zuckerman College of Public Health, University of Arizona (BioMed Central Ltd, 2021)
      Background: Tramadol is a widely used synthetic opioid for moderate to severe pain. Some studies have shown that tramadol can increase oxidative stress in different tissues of the body. Quercetin is also a substance with various biological effects, including antioxidant, anti-inflammatory, hepatoprotective, nephroprotective, and cardioprotective activities. The current investigation aimed at determining the effects of quercetin, with or without naloxone, on tramadol intoxication. Methods: This study was performed on 30 male Wistar rats divided into five groups: Group I) control group: intraperitoneal injections of normal saline 0.9% for 14 days; Group II) tramadol: 25 mg/kg for 14 days, and then a 50 mg/kg acute dose injection on the last day; Group III) acute quercetin (single dose): tramadol injection as with the second group plus 100 mg/kg of quercetin on the last day; Group IV) chronic quercetin: tramadol injection similar to the second group plus quercetin 100 mg/kg for 14 days; Group V) quercetin plus naloxone: tramadol injection similar to the second group plus injection of quercetin 100 mg/kg + intravenous naloxone 2 mg/kg on the last day, followed by a 4 mg/kg/h injection of naloxone for six hours. The rats were monitored for six hours on the last day, relating to the number and severity of seizures. Finally, the samples were prepared for biochemical investigation of the serum level of oxidative stress markers (MDA, SOD, NOx), inflammatory factors (IL-6, TNF-α), biochemical parameters (ALT, AST, creatinine, glucose) and hematological assay. The liver, heart, kidney, cortex, cerebellum, and adrenal tissues were collected to investigate the redox state. Results: None of the treatments had positive effects on the number and severity of seizures. Chronic administration of quercetin led to alteration of some blood parameters, including reduced hemoglobin level and elevated platelet counts. Acute on chronic tramadol administration resulted in a significant rise in AST, where different treatments failed to reduce their levels down to the control group. Conclusion: chronic administration of quercetin showed decreased oxidative/nitrosative stress in the liver, kidney, adrenal, and heart tissues. Quercetin plus naloxone decreased oxidative stress in the heart and adrenal tissues, but adverse effects on the brain cortex and hepatic function. Single-dose quercetin reduced cardiac oxidative stress. © 2021, The Author(s).
    • The Effects of Repeated Morphine Treatment on the Endogenous Cannabinoid System in the Ventral Tegmental Area

      Zhang, H.; Lipinski, A.A.; Liktor-Busa, E.; Smith, A.F.; Moutal, A.; Khanna, R.; Langlais, P.R.; Largent-Milnes, T.M.; Vanderah, T.W.; Department of Pharmacology, College of Medicine, University of Arizona; et al. (Frontiers Media S.A., 2021)
      The therapeutic utility of opioids is diminished by their ability to induce rewarding behaviors that may lead to opioid use disorder. Recently, the endogenous cannabinoid system has emerged as a hot topic in the study of opioid reward but relatively little is known about how repeated opioid exposure may affect the endogenous cannabinoid system in the mesolimbic reward circuitry. In the present study, we investigated how sustained morphine may modulate the endogenous cannabinoid system in the ventral tegmental area (VTA) of Sprague Dawley rats, a critical region in the mesolimbic reward circuitry. Studies here using proteomic analysis and quantitative real-time PCR (qRT-PCR) found that the VTA expresses 32 different proteins or genes related to the endogenous cannabinoid system; three of these proteins or genes (PLCγ2, ABHD6, and CB2R) were significantly affected after repeated morphine exposure (CB2R was only detected by qRT-PCR but not proteomics). We also identified that repeated morphine treatment does not alter either anandamide (AEA) or 2-arachidonoylglycerol (2-AG) levels in the VTA compared to saline treatment; however, there may be diminished levels of anandamide (AEA) production in the VTA 4 h after a single morphine injection in both chronic saline and morphine pretreated cohorts. Treating the animals with an inhibitor of 2-AG degradation significantly decreased repeated opioid rewarding behavior. Taken together, our studies reveal a potential influence of sustained opioids on the endocannabinoid system in the VTA, suggesting that the endogenous cannabinoid system may participate in the opioid-induced reward. © Copyright © 2021 Zhang, Lipinski, Liktor-Busa, Smith, Moutal, Khanna, Langlais, Largent-Milnes and Vanderah.
    • The Enhancement of Proton Stochastic Heating in the Near-Sun Solar Wind

      Martinovic, Mihailo M.; Klein, Kristopher G.; Kasper, Justin C.; Case, Anthony W.; Korreck, Kelly E.; Larson, Davin; Livi, Roberto; Stevens, Michael; Whittlesey, Phyllis; Chandran, Benjamin D. G.; et al. (IOP PUBLISHING LTD, 2020-02)
      Stochastic heating (SH) is a nonlinear heating mechanism driven by the violation of magnetic moment invariance due to large-amplitude turbulent fluctuations producing diffusion of ions toward higher kinetic energies in the direction perpendicular to the magnetic field. It is frequently invoked as a mechanism responsible for the heating of ions in the solar wind. Here, we quantify for the first time the proton SH rate Q(perpendicular to) at radial distances from the Sun as close as 0.16 au, using measurements from the first two Parker Solar Probe encounters. Our results for both the amplitude and radial trend of the heating rate, Q(perpendicular to) proportional to r(-2.5), agree with previous results based on the Helios data set at heliocentric distances from 0.3 to 0.9 au. Also in agreement with previous results, Q(perpendicular to) is significantly larger in the fast solar wind than in the slow solar wind. We identify the tendency in fast solar wind for cuts of the core proton velocity distribution transverse to the magnetic field to exhibit a flattop shape. The observed distribution agrees with previous theoretical predictions for fast solar wind where SH is the dominant heating mechanism.
    • The Enhancement of Proton Stochastic Heating in the Near-Sun Solar Wind

      Martinovic, Mihailo M.; Klein, Kristopher G.; Kasper, Justin C.; Case, Anthony W.; Korreck, Kelly E.; Larson, Davin; Livi, Roberto; Stevens, Michael; Whittlesey, Phyllis; Chandran, Benjamin D. G.; et al. (IOP PUBLISHING LTD, 2020-02)
      Stochastic heating (SH) is a nonlinear heating mechanism driven by the violation of magnetic moment invariance due to large-amplitude turbulent fluctuations producing diffusion of ions toward higher kinetic energies in the direction perpendicular to the magnetic field. It is frequently invoked as a mechanism responsible for the heating of ions in the solar wind. Here, we quantify for the first time the proton SH rateQat radial distances from the Sun as close as 0.16 au, using measurements from the first twoParker Solar Probeencounters. Our results for both the amplitude and radial trend of the heating rate,Q proportional to r(-2.5), agree with previous results based on theHeliosdata set at heliocentric distances from 0.3 to 0.9 au. Also in agreement with previous results,Qis significantly larger in the fast solar wind than in the slow solar wind. We identify the tendency in fast solar wind for cuts of the core proton velocity distribution transverse to the magnetic field to exhibit a flattop shape. The observed distribution agrees with previous theoretical predictions for fast solar wind where SH is the dominant heating mechanism.
    • The Epoch of Giant Planet Migration Planet Search Program. I. Near-infrared Radial Velocity Jitter of Young Sun-like Stars

      Tran, Q.H.; Bowler, B.P.; Cochran, W.D.; Endl, M.; Stefánsson, G.; Mahadevan, S.; Ninan, J.P.; Bender, C.F.; Halverson, S.; Roy, A.; et al. (American Astronomical Society, 2021)
      We present early results from the Epoch of Giant Planet Migration program, a precise radial velocity (RV) survey of more than 100 intermediate-age (∼20-200 Myr) G and K dwarfs with the Habitable Zone Planet Finder spectrograph (HPF) at McDonald Observatory's Hobby-Eberly Telescope. The goals of this program are to determine the timescale and dominant physical mechanism of giant planet migration interior to the water ice line of Sun-like stars. Here, we summarize results from the first 14 months of this program, with a focus on our custom RV pipeline for HPF, a measurement of the intrinsic near-infrared RV activity of young Solar analogs, and modeling the underlying population-level distribution of stellar jitter. We demonstrate on-sky stability at the sub-2 m s-1 level for the K2 standard HD 3765 using a least-squares matching method to extract precise RVs. Based on a subsample of 29 stars with at least three RV measurements from our program, we find a median rms level of 34 m s-1. This is nearly a factor of 2 lower than the median rms level in the optical of 60 m s-1 for a comparison sample with similar ages and spectral types as our targets. The observed near-infrared jitter measurements for this subsample are well reproduced with a log-normal parent distribution with μ = 4.15 and σ = 1.02. Finally, by compiling rms values from previous planet search programs, we show that near-infrared jitter for G and K dwarfs generally decays with age in a similar fashion to optical wavelengths, albeit with a shallower slope and lower overall values for ages ≲1 Gyr. © 2021. The American Astronomical Society. All rights reserved..
    • The ESCAPE mission overview: Exploring the stellar drivers of exoplanet habitability

      France, K.; Fleming, B.; Youngblood, A.; Mason, J.; Drake, J.J.; Amerstorfer, U.; Barstow, M.; Bourrier, V.; Champey, P.; Fossati, L.; et al. (SPIE, 2021)
      The Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution (ESCAPE) mission is an astrophysics Small Explorer employing ultraviolet spectroscopy (EUV: 80-825 Å and FUV: 1280-1650 Å) to explore the high-energy radiation environment in the habitable zones around nearby stars. ESCAPE provides the first comprehensive study of the stellar EUV and coronal mass ejection environments which directly impact the habitability of rocky exoplanets. In a 20 month science mission, ESCAPE will provide the essential stellar characterization to identify exoplanetary systems most conducive to habitability and provide a roadmap for NASAs future life-finder missions. ESCAPE accomplishes this goal with roughly two-order-of-magnitude gains in EUV efficiency over previous missions. ESCAPE employs a grazing incidence telescope that feeds an EUV and FUV spectrograph. The ESCAPE science instrument builds on previous ultraviolet and X-ray instrumentation, grazing incidence optical systems, and photon-counting ultraviolet detectors used on NASA astrophysics, heliophysics, and planetary science missions. The ESCAPE spacecraft bus is the versatile and high-heritage Ball Aerospace BCP-Small spacecraft. Data archives will be housed at the Mikulski Archive for Space Telescopes (MAST). ESCAPE is currently completing a NASA Phase A study, and if selected for Phase B development would launch in 2025. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
    • The Evolution and Role of Solar Wind Turbulence in the Inner Heliosphere

      Chen, C. H. K.; Bale, S. D.; Bonnell, J. W.; Borovikov, D.; Bowen, T. A.; Burgess, D.; Case, A. W.; Chandran, B. D. G.; de Wit, T. Dudok; Goetz, K.; et al. (IOP PUBLISHING LTD, 2020-02)
      The first two orbits of the Parker Solar Probe spacecraft have enabled the first in situ measurements of the solar wind down to a heliocentric distance of 0.17 au (or 36 R-circle dot). Here, we present an analysis of this data to study solar wind turbulence at 0.17 au and its evolution out to 1 au. While many features remain similar, key differences at 0.17 au include increased turbulence energy levels by more than an order of magnitude, a magnetic field spectral index of -3/2 matching that of the velocity and both Elsasser fields, a lower magnetic compressibility consistent with a smaller slow-mode kinetic energy fraction, and a much smaller outer scale that has had time for substantial nonlinear processing. There is also an overall increase in the dominance of outward-propagating Alfvenic fluctuations compared to inward-propagating ones, and the radial variation of the inward component is consistent with its generation by reflection from the large-scale gradient in Alfven speed. The energy flux in this turbulence at 0.17 au was found to be similar to 10% of that in the bulk solar wind kinetic energy, becoming similar to 40% when extrapolated to the Alfven point, and both the fraction and rate of increase of this flux toward the Sun are consistent with turbulence-driven models in which the solar wind is powered by this flux.