Now showing items 5878-5897 of 10044

    • Molecular evolutionary analysis of a gender-limited MID ortholog from the homothallic species Volvox africanus with male and monoecious spheroids

      Yamamoto, Kayoko; Kawai-Toyooka, Hiroko; Hamaji, Takashi; Tsuchikane, Yuki; Mori, Toshiyuki; Takahashi, Fumio; Sekimoto, Hiroyuki; Ferris, Patrick J.; Nozaki, Hisayoshi; Univ Arizona, Dept Ecol & Evolutionary Biol (PUBLIC LIBRARY SCIENCE, 2017-06-30)
      Volvox is a very interesting oogamous organism that exhibits various types of sexuality and/or sexual spheroids depending upon species or strains. However, molecular bases of such sexual reproduction characteristics have not been studied in this genus. In the model species V. carteri, an ortholog of the minus mating type-determining or minus dominance gene (MID) of isogamous Chlamydomonas reinhardtii is male-specific and determines the sperm formation. Male and female genders are genetically determined (heterothallism) in V. carteri, whereas in several other species of Volvox both male and female gametes (sperm and eggs) are formed within the same clonal culture (homothallism). To resolve the molecular basis of the evolution of Volvox species with monoecious spheroids, we here describe a MID ortholog in the homothallic species V. africanus that produces both monoecious and male spheroids within a single clonal culture. Comparison of synonymous and nonsynonymous nucleotide substitutions in MID genes between V. africanus and heterothallic volvocacean species suggests that the MID gene of V. africanus evolved under the same degree of functional constraint as those of the heterothallic species. Based on semi quantitative reverse transcription polymerase chain reaction analyses using the asexual, male and monoecious spheroids isolated from a sexually induced V. africanus culture, the MID mRNA level was significantly upregulated in the male spheroids, but suppressed in the monoecious spheroids. These results suggest that the monoecious spheroid-specific down regulation of gene expression of the MID homolog correlates with the formation of both eggs and sperm in the same spheroid in V. africanus.
    • Molecular gas and star formation activity in luminous infrared galaxies in clusters at intermediate redshifts

      Castignani, G.; Jablonka, P.; Combes, F.; Haines, C. P.; Rawle, T.; Jauzac, M.; Egami, E.; Krips, M.; Sperone-Longin, D.; Arnaud, M.; et al. (EDP SCIENCES S A, 2020-08)
      We investigate the role of dense megaparsec-scale environments in processing molecular gas of cluster galaxies as they fall into the cluster cores. We selected a sample of similar to 20 luminous infrared galaxies (LIRGs) belonging to intermediate-redshift clusters, mainly from the Herschel Lensing Survey and the Local Cluster Substructure Survey. These galaxies include MACS J0717.5+3745 at z=0.546 and Abell 697, 963, 1763, and 2219 at z=0.2-0.3. We performed spectral energy distribution modeling from the far-infrared to ultraviolet of the LIRGs, which span cluster-centric distances within r/r(200)similar or equal to 0.2-1.6. We observed the LIRGs in CO(1 -> 0) or CO(2 -> 1) with the Plateau de Bure interferometer and its successor NOEMA, as part of five observational programs carried out between 2012 and 2017. We compared the molecular gas to stellar mass ratio M(H-2)/M-star, star formation rate (SFR), and depletion time (tau (dep)) of the LIRGs with those of a compilation of cluster and field star-forming galaxies from the literature. The targeted LIRGs have SFR, M(H-2)/M-star, and tau (dep) that are consistent with those of both main-sequence (MS) field galaxies and star-forming galaxies from the comparison sample. However we find that the depletion time, normalized to the MS value, tentatively increases with increasing r/r(200), with a significance of 2.8 sigma, which is ultimately due to a deficit of cluster-core LIRGs with tau (dep)greater than or similar to tau (dep, MS). We suggest that a rapid exhaustion of the molecular gas reservoirs occurs in the cluster LIRGs and is indeed effective in suppressing their star formation and ultimately quenching them. This mechanism may explain the exponential decrease of the fraction of cluster LIRGs with cosmic time. The compression of the gas in LIRGs, possibly induced by intra-cluster medium shocks, may be responsible for the short timescales that are observed in a large fraction of cluster-core LIRGs. Some of our LIRGs may also belong to a population of infalling filament galaxies.
    • Molecular Gas Contents and Scaling Relations for Massive, Passive Galaxies at Intermediate Redshifts from the LEGA-C Survey

      Spilker, Justin; Bezanson, Rachel; Barišić, Ivana; Bell, Eric; P. Lagos, Claudia del; Maseda, Michael; Muzzin, Adam; Pacifici, Camilla; Sobral, David; Straatman, Caroline; et al. (IOP PUBLISHING LTD, 2018-06-20)
      A decade of study has established that the molecular gas properties of star-forming galaxies follow coherent scaling relations out to z similar to 3, suggesting remarkable regularity of the interplay between molecular gas, star formation, and stellar growth. Passive galaxies, however, are expected to be gas-poor and therefore faint, and thus little is known about molecular gas in passive galaxies beyond the local universe. Here we present deep Atacama Large Millimeter/submillimeter Array observations of CO(2-1) emission in eight massive (M-star similar to 10(11 )M(circle dot)) galaxies at z similar to 0.7 selected to lie a factor of 3-10 below the star-forming sequence at this redshift, drawn from the Large Early Galaxy Astrophysics Census survey. We significantly detect half the sample, finding molecular gas fractions less than or similar to 0.1. We show that the molecular and stellar rotational axes are broadly consistent, arguing that the molecular gas was not accreted after the galaxies became quiescent. We find that scaling relations extrapolated from the star-forming population overpredict both the gas fraction and gas depletion time for passive objects, suggesting the existence of either a break or large increase in scatter in these relations at low specific star formation rate. Finally, we show that the gas fractions of the passive galaxies we have observed at intermediate redshifts are naturally consistent with evolution into local, massive early-type galaxies by continued low-level star formation, with no need for further gas accretion or dynamical stabilization of the gas reservoirs in the intervening 6 billion years.
    • Molecular gas during the post-starburst phase: low gas fractions in green-valley Seyfert post-starburst galaxies

      Yesuf, Hassen M.; French, K. Decker; Faber, S. M.; Koo, David C.; Univ Arizona, Steward Observ (OXFORD UNIV PRESS, 2017-08)
      Post-starbursts (PSBs) are candidate for rapidly transitioning from starbursting to quiescent galaxies. We study the molecular gas evolution of PSBs at z similar to 0.03-0.2. We undertook new CO (2-1) observations of 22 Seyfert PSB candidates using the Arizona Radio Observatory Submillimeter Telescope. This sample complements previous samples of PSBs by including green-valley PSBs with Seyfert-like emission, allowing us to analyse for the first time the molecular gas properties of 116 PSBs with a variety of AGN properties. The distribution of molecular gas to stellar mass fractions in PSBs is significantly different from normal star-forming galaxies in the CO Legacy Database (COLD) GASS survey. The combined samples of PSBs with Seyfert-like emission line ratios have a gas fraction distribution that is even more significantly different and is broader (similar to 0.03-0.3). Most of them have lower gas fractions than normal star-forming galaxies. We find a highly significant correlation between the WISE 12 and 4.6 mu m flux ratios and molecular gas fractions in both PSBs and normal galaxies. We detect molecular gas in 27 per cent of our Seyfert PSBs. Taking into account the upper limits, the mean and the dispersion of the distribution of the gas fraction in our Seyfert PSB sample are much smaller (mu = 0.025, sigma = 0.018) than previous samples of Seyfert PSBs or PSBs in general (mu similar to 0.1-0.2, sigma similar to 0.1-0.2).
    • Molecular gas properties of a lensed star-forming galaxy at z ~ 3.6: a case study

      Dessauges-Zavadsky, M.; Zamojski, M.; Rujopakarn, W.; Richard, J.; Sklias, P.; Schaerer, D.; Combes, F.; Ebeling, H.; Rawle, T. D.; Egami, E.; et al. (EDP SCIENCES S A, 2017-09-14)
      We report on the galaxy MACSJ0032-arc at z(CO) = 3.6314 discovered during the Herschel Lensing snapshot Survey of massive galaxy clusters, and strongly lensed by the cluster MACSJ0032.1+1808. The successful detections of its rest-frame ultraviolet (UV), optical, far-infrared (FIR), millimeter, and radio continua, and of its CO emission enable us to characterize, for the first time at such a high redshift, the stellar, dust, and molecular gas properties of a compact star-forming galaxy with a size smaller than 2.5 kpc, a fairly low stellar mass of 4.8(-1.0)(+0.5) x 10(9) M circle dot, and a moderate IR luminosity of 4.8(-0.6)(+1.2) x 10(11) L circle dot. By combining the stretching effect of the lens with the high angular resolution imaging of the CO(10) line emission and the radio continuum at 5 GHz, we find that the bulk of the molecular gas mass and star formation seems to be spatially decoupled from the rest-frame UV emission. About 90% of the total star formation rate is undetected at rest-frame UV wavelengths because of severe obscuration by dust, but is seen through the thermal FIR dust emission and the radio synchrotron radiation. The observed CO(43) and CO(65) lines demonstrate that high-J transitions, at least up to J = 6, remain excited in this galaxy, whose CO spectral line energy distribution resembles that of high-redshift submm galaxies, even though the IR luminosity of MACSJ0032-arc is ten times lower. This high CO excitation is possibly due to the compactness of the galaxy. We find evidence that this high CO excitation has to be considered in the balance when estimating the CO-to-H-2 conversion factor. Indeed, the respective CO-to-H-2 conversion factors as derived from the correlation with metallicity and the FIR dust continuum can only be reconciled if excitation is accounted for. The inferred depletion time of the molecular gas in MACSJ0032-arc supports the decrease in the gas depletion timescale of galaxies with redshift, although to a lesser degree than predicted by galaxy evolution models. Instead, the measured molecular gas fraction as high as 6079% in MACSJ0032-arc favors the continued increase in the gas fraction of galaxies with redshift as expected, despite the plateau observed between z similar to 1.5 and z similar to 2.5.
    • A molecular mechanism for the procentriole recruitment of Ana2

      McLamarrah, Tiffany A; Speed, Sarah K; Ryniawec, John M; Buster, Daniel W; Fagerstrom, Carey J; Galletta, Brian J; Rusan, Nasser M; Rogers, Gregory C; Univ Arizona, Canc Ctr, Dept Cellular & Mol Med (ROCKEFELLER UNIV PRESS, 2019-12-16)
      During centriole duplication, a preprocentriole forms at a single site on the mother centriole through a process that includes the hierarchical recruitment of a conserved set of proteins, including the Polo-like kinase 4 (Plk4), Ana2/STIL, and the cartwheel protein Sas6. Ana2/STIL is critical for procentriole assembly, and its recruitment is controlled by the kinase activity of Plk4, but how this works remains poorly understood. A structural motif called the G-box in the centriole outer wall protein Sas4 interacts with a short region in the N terminus of Ana2/STIL. Here, we show that binding of Ana2 to the Sas4 G-box enables hyperphosphorylation of the Ana2 N terminus by Plk4. Hyperphosphorylation increases the affinity of the Ana2-G-box interaction, and, consequently, promotes the accumulation of Ana2 at the procentriole to induce daughter centriole formation.
    • Molecular mechanisms of bio-catalysis of heme extraction from hemoglobin

      Sakipov, Serzhan; Rafikova, Olga; Kurnikova, Maria G.; Rafikov, Ruslan; Univ Arizona, Dept Med (ELSEVIER SCIENCE BV, 2017-04)
      Red blood cell hemolysis in sickle cell disease (SCD) releases free hemoglobin. Extracellular hemoglobin and its degradation products, free heme and iron, are highly toxic due to oxidative stress induction and decrease in nitric oxide availability. We propose an approach that helps to eliminate extracellular hemoglobin toxicity in SCD by employing a bacterial protein system that evolved to extract heme from extracellular hemoglobin. NEAr heme Transporter (NEAT) domains from iron-regulated surface determinant proteins from Staphylococcus aureus specifically bind free heme as well as facilitate its extraction from hemoglobin. We demonstrate that a purified NEAT domain fused with human haptoglobin beta-chain is able to remove heme from hemoglobin and reduce heme content and peroxidase activity of hemoglobin. We further use molecular dynamics (MD) simulations to resolve molecular pathway of heme transfer from hemoglobin to NEAT, and to elucidate molecular mechanism of such heme transferring process. Our study is the first of its kind, in which simulations are employed to characterize the process of heme leaving hemoglobin and subsequent rebinding with a NEAT domain. Our MD results highlight important amino acid residues that facilitate heme transfer and will guide further studies for the selection of best NEAT candidate to attenuate free hemoglobin toxicity.
    • Molecular Oxygen in the Nearest QSO Mrk 231

      Wang, Junzhi; Li, Di; Goldsmith, Paul F.; Zhang, Zhi-Yu; Gao, Yu; Shi, Yong; Li, Shanghuo; Fang, Min; Li, Juan; Zhang, Jiangshui; et al. (IOP PUBLISHING LTD, 2020-01-30)
      We report the detection of an emission feature at the 12 sigma level with FWHM line width of about 450 km s(-1) toward the nearest quasi-stellar object, QSO Mrk 231. Based on observations with the IRAM 30 m telescope and the Northern Extended Millimeter Array Interferometer, the 1(1)-1(0) transition of molecular oxygen is the likely origin of the line with rest frequency close to 118.75 GHz. The velocity of the O-2 emission in Mrk 231 coincides with the red wing seen in CO emission, suggesting that it is associated with the outflowing molecular gas, located mainly at about 10 kpc away from the central active galactic nucleus (AGN). This first detection of extragalactic molecular oxygen provides an ideal tool to study AGN-driven molecular outflows on dynamic timescales of tens of megayears. O-2 may be a significant coolant for molecular gas in such regions affected by AGN-driven outflows. New astrochemical models are needed to explain the implied high molecular oxygen abundance in such regions several kiloparsecs away from the center of galaxies.
    • Molecular Profiling of Benign Metastasizing Leiomyoma of the Uterus Revealing Unique Novel Therapeutic Targets

      Findakly, Dawood; Wang, Jue; Univ Arizona, Canc Ctr Dign Hlth St Josephs (CUREUS INC, 2020-04-16)
      Extra-uterine manifestations of benign uterine leiomyoma (fibroids) are rare. Benign metastasizing leiomyoma (BML) comprises an uncommon variant characterized by metastatic lung nodules. The pathologic characteristics for BML are well known in the literature; however, the underlying biology and molecular mechanisms remain poorly understood. We present a case of a 43-year-old woman who presented to the hospital complaining of dyspnea and lower extremity edema. Medical history includes a previous hysterectomy for leiomyomata two years prior. A reduced ejection fraction and right atrium globular filling defect are seen on transthoracic echo (TTE). CT scans of the chest, abdomen, and pelvis reported pelvic mass with an extensive inferior vena cava (IVC) thrombus extending into the right atrium, which was subsequently completely resected. Subsequent histopathology for the thrombus reported intravascular leiomyomatosis (IVL) and pelvic mass reported benign leiomyoma. Two years later, the symptoms recurred, and a chest CT revealed new pulmonary nodules. Subsequent pathology from a biopsy of these nodules was consistent with BML with ER+/PR+ on immunohistochemical staining. Genetic testing showed amplification of JUN, cyclin-dependent kinase 4 (CDK4), and MCL1, and loss of SUFU, AT-rich interaction domain 1A (AR1D1A), RB transcriptional corepressor 1 (RBI), and hepatocyte nuclear factor 1-alpha (HNF1A). The patient deemed to be a poor surgical candidate, and, therefore, she was started on hormonal treatment with leuprolide and letrozole. The disease remained stable upon follow-up at 48 months. Here, we report novel genomic profiling findings for the first time in a patient with a newly diagnosed BML. These findings may suggest molecular evidence that IVL may not be as benign as previously thought. Our study further highlights the value of genetic profiling in the understanding of this tumor's behavior and identification of new patient-specific therapeutic targets.
    • “Mom, I want to come home”: Geographies of compound displacement, violence and longing

      Myadar, Orhon; Davidson, Ronald A.; Univ Arizona, Sch Geog & Dev (PERGAMON-ELSEVIER SCIENCE LTD, 2020-02)
      This article focuses on former "comfort woman" Gil Won-ok's story to explore the dialectical relationship between place and self, or what Edward Casey calls the "geographical self." Gil was one of thousands of women who were used as sex slaves by the Imperial Army of Japan at "comfort stations" during World War II. Taken from her hometown of Pyongyang when she was fourteen years old, Gil endured years of compounding violence in displacement away from her family and homeland. Today, at age 92, Gil still does not know what happened to her family as the division of Korea prevented her from returning home, extending her displacement. Despite the scale and brutal nature of this state-sponsored violence against thousands of young women and girls, geographic scholarship is critically lacking in addressing this violence. We hope to fill this gap. Theoretically, the article contributes to the broader literature on the dyad of place and self, and we do so by broadening the discussion of the geographical self to better understand the violence of displacement and longing for one's lost place. But most importantly this article would make a modest contribution of recognition to Gil's long struggle and perseverance.
    • Moment-based metrics for global sensitivity analysis of hydrological systems

      Dell'Oca, Aronne; Riva, Monica; Guadagnini, Alberto; Univ Arizona, Dept Hydrol & Atmospher Sci (COPERNICUS GESELLSCHAFT MBH, 2017-12-08)
      We propose new metrics to assist global sensitivity analysis, GSA, of hydrological and Earth systems. Our approach allows assessing the impact of uncertain parameters on main features of the probability density function, pdf, of a target model output, y. These include the expected value of y, the spread around the mean and the degree of symmetry and tailedness of the pdf of y. Since reliable assessment of higher-order statistical moments can be computationally demanding, we couple our GSA approach with a surrogate model, approximating the full model response at a reduced computational cost. Here, we consider the generalized polynomial chaos expansion (gPCE), other model reduction techniques being fully compatible with our theoretical framework. We demonstrate our approach through three test cases, including an analytical benchmark, a simplified scenario mimicking pumping in a coastal aquifer and a laboratory-scale conservative transport experiment. Our results allow ascertaining which parameters can impact some moments of the model output pdf while being uninfluential to others. We also investigate the error associated with the evaluation of our sensitivity metrics by replacing the original system model through a gPCE. Our results indicate that the construction of a surrogate model with increasing level of accuracy might be required depending on the statistical moment considered in the GSA. The approach is fully compatible with (and can assist the development of) analysis techniques employed in the context of reduction of model complexity, model calibration, design of experiment, uncertainty quantification and risk assessment.
    • Momentary affect, stress coping, and food intake in mother-child dyads

      Mason, Tyler B; O'Connor, Sydney G; Schembre, Susan M; Huh, Jimi; Chu, Daniel; Dunton, Genevieve F; Univ Arizona, Dept Family & Community Med (AMER PSYCHOLOGICAL ASSOC, 2019-03-01)
      Momentary affect and stress in mothers and their children may be an important predictor of food intake in the natural environment. This study hypothesized that there would be parallel actor and partner effects such that mothers' and children's negative affect (NA), positive affect (PA), and ability to cope with stress would be associated with their own and the other dyad member's unhealthy and healthy food intake in a similar pattern. Method: Participants included 202 mother-child dyads (child age range = 8-12 years) who responded to randomly prompted ecological momentary assessment surveys via smartphone up to 7 times per day over 8 days, excluding time at school. At each prompt, mothers and children reported on their current NA, PA, and ability to cope with stress and foods consumed in the past 2 hr. Results: Mothers' momentary ability to cope with stress predicted their own and their child's pastries/sweets intake and their own fries/chips intake, and children's momentary ability to cope with stress predicted their own pastries/sweets intake. Mothers and children who reported higher NA on average consumed more pastries/sweets, and children with higher NA on average consumed more fast food. Finally, mothers' momentary PA predicted their own fruit/vegetable consumption. Conclusions: Findings provided evidence that the affect and ability to cope with stress of children and mothers predicted subsequent food intake. Given both actor and partner effects, the results show that targeting momentary mothers' and children's ability to cope with stress may have the greatest effect on reducing unhealthy food intake.
    • Mometasone or Tiotropium in Mild Asthma with a Low Sputum Eosinophil Level

      Martinez, Fernando D; Morgan, Wayne J; Univ Arizona, Arizona Resp Ctr (MASSACHUSETTS MEDICAL SOC, 2019-05-19)
      Background: In many patients with mild, persistent asthma, the percentage of eosinophils in sputum is less than 2% (low eosinophil level). The appropriate treatment for these patients is unknown. Methods In this 42-week, double-blind, crossover trial, we assigned 295 patients who were at least 12 years of age and who had mild, persistent asthma to receive mometasone (an inhaled glucocorticoid), tiotropium (a long-acting muscarinic antagonist), or placebo. The patients were categorized according to the sputum eosinophil level (<2% or >= 2%). The primary outcome was the response to mometasone as compared with placebo and to tiotropium as compared with placebo among patients with a low sputum eosinophil level who had a prespecified differential response to one of the trial agents. The response was determined according to a hierarchical composite outcome that incorporated treatment failure, asthma control days, and the forced expiratory volume in 1 second; a two-sided P value of less than 0.025 denoted statistical significance. A secondary outcome was a comparison of results in patients with a high sputum eosinophil level and those with a low level. Results: A total of 73% of the patients had a low eosinophil level; of these patients, 59% had a differential response to a trial agent. However, there was no significant difference in the response to mometasone or tiotropium, as compared with placebo. Among the patients with a low eosinophil level who had a differential treatment response, 57% (95% confidence interval [CI], 48 to 66) had a better response to mometasone, and 43% (95% CI, 34 to 52) had a better response to placebo (P=0.14). In contrast 60% (95% CI, 51 to 68) had a better response to tiotropium, whereas 40% (95% CI, 32 to 49) had a better response to placebo (P=0.029). Among patients with a high eosinophil level, the response to mometasone was significantly better than the response to placebo (74% vs. 26%) but the response to tiotropium was not (57% vs. 43%). Conclusions: The majority of patients with mild, persistent asthma had a low sputum eosinophil level and had no significant difference in their response to either mometasone or tiotropium as compared with placebo. These data provide equipoise for a clinically directive trial to compare an inhaled glucocorticoid with other treatments in patients with a low eosinophil level. (Funded by the National Heart, Lung, and Blood Institute; SIENA number, .) In this trial involving patients with mild, persistent asthma, there was no significant difference in therapeutic effect between an inhaled glucocorticoid (mometasone) and placebo in patients with a low sputum eosinophil level (<2%), which was reported in nearly three quarters of the patients.
    • Monasone Naphthoquinone Biosynthesis and Resistance in Monascus Fungi

      Li, Mu; Kang, Lijing; Ding, Xiaoli; Liu, Jiao; Liu, Qingpei; Shao, Yanchun; Molnár, István; Chen, Fusheng; Univ Arizona, Coll Agr & Life Sci, Southwest Ctr Nat Prod Res (AMER SOC MICROBIOLOGY, 2020-02-04)
      Despite the important biological activities of natural product naphthoquinones, the biosynthetic pathways of and resistance mechanisms against such compounds remain poorly understood in fungi. Here, we report that the genes responsible for the biosynthesis of Monascus naphthoquinones (monasones) reside within the gene cluster for Monascus azaphilone pigments (MonAzPs). We elucidate the biosynthetic pathway of monasones by a combination of comparative genome analysis, gene knockouts, heterologous coexpression, and in vivo and in vitro enzymatic reactions to show that this pathway branches from the first polyketide intermediate of MonAzPs. Furthermore, we propose that the monasone subset of biosynthetic genes also encodes a two-tiered resistance strategy in which an inducible monasone-specific exporter expels monasones from the mycelia, while residual intracellular monasones may be rendered nontoxic through a multistep reduction cascade.IMPORTANCE The genes for Monascus naphthoquinone (monasone) biosynthesis are embedded in and form a composite supercluster with the Monascus azaphilone pigment biosynthetic gene cluster. Early biosynthetic intermediates are shared by the two pathways. Some enzymes encoded by the supercluster play double duty in contributing to both pathways, while others are specific for one or the other pathway. The monasone subcluster is independently regulated and inducible by elicitation with competing microorganisms. This study illustrates genomic and biosynthetic parsimony in fungi and proposes a potential path for the evolution of the mosaic-like azaphilone-naphthoquinone supercluster. The monasone subcluster also encodes a two-tiered self-resistance mechanism that models resistance determinants that may transfer to target microorganisms or emerge in cancer cells in case of naphthoquinone-type cytotoxic agents.
    • Monitoring damage in composite plates from crack initiation to macro-crack propagation combining linear and nonlinear ultrasonic techniques

      Alnuaimi, Hamad; Amjad, Umar; Russo, Pietro; Lopresto, Valentina; Kundu, Tribikram; Univ Arizona, Dept Civil & Architectural Engn & Mech (SAGE Publications, 2020-06-07)
      In this article, a holistic technique for sensing damage initiation, as well as damage progression in composite plates, is presented combining linear and nonlinear ultrasonic techniques. For this investigation, multiple sets of composite plate specimens made of two different composite materials were fabricated to check if the proposed technique works for different types of specimens. The specimens were damaged by impact loading and then inspected by propagating Lamb waves through them. Different failure mechanisms, such as fiber breaks, matrix cracking, debonding, and delamination, cause composite damage. Two groups of composite specimens that were fabricated and damaged were glass fiber-reinforced polymer composite and basalt fiber-reinforced polymer composite. A chirp signal excited by PZT (lead zirconate titanate) transducer was propagated through undamaged and damaged specimens to investigate the effects of varying degrees of damage on the recorded signals. Both linear and nonlinear ultrasonic parameters were extracted from the recorded signals and analyzed. The change in the linear ultrasonic parameters such as the wave speed and attenuation with damage progression were recorded. A new nonlinear ultrasonic parameter, the sideband peak count or sideband peak count-index, is also introduced and calculated from the recorded signals. It is observed that the nonlinear ultrasonic parameter can monitor the early stage of damage progression better than the linear ultrasonic parameters, while some linear ultrasonic parameters are more effective than the nonlinear ultrasonic parameter for monitoring the advanced stage of damage. Therefore, a combination of linear ultrasonic and nonlinear ultrasonic analyses is ideal for the holistic monitoring of the composite panels from the crack nucleation stage to the structural failure stage.
    • Monitoring of Dust Devil Tracks Around the InSight Landing Site, Mars, and Comparison With In Situ Atmospheric Data

      Perrin, C.; Rodriguez, S.; Jacob, A.; Lucas, A.; Spiga, A.; Murdoch, N.; Lorenz, R.; Daubar, I. J.; Pan, L.; Kawamura, T.; et al. (AMER GEOPHYSICAL UNION, 2020-05)
      The NASA InSight mission on Mars is a unique opportunity to study atmospheric processes both from orbit and in situ observations. We use post-landing high-resolution satellite images to monitor dust devil activity during the first 8 months of the mission. We perform mapping and semiautomatic detection of newly formed dust devil tracks and analyze their characteristics (sizes, azimuths, distances, and directions of motion). We find a large number of tracks appearing shortly after landing, followed by a significant decrease of activity during late winter, then a progressive increase during early spring. New tracks are characterized by dark linear, to slightly curvilinear, traces ranging from a few to more than 10 m wide. Tracks are oriented in the ambient wind direction, according to measurements made by InSight's meteorological sensors. The systematic analysis of dust devil tracks is useful to have a better understanding of atmospheric and aeolian activity around InSight. Plain Language Summary The NASA InSight mission landed on Mars in November 2018. It carries weather and seismic stations that are now working continuously. We are also able to observe the InSight region from orbit using high-resolution satellite images that have been acquired regularly over the first year of the InSight mission. They show a lot of dark traces on the surface, which are caused by whirlwinds called dust devils raising dust into the air. This phenomenon is not observed at the same rate over the entire year, as it depends on atmospheric conditions that vary with season. Our study with satellite images allows us to understand the characteristics of dust devil tracks and compare them with related measurements from the weather station on board InSight. These two sets of observations are well correlated to each other and provide significant constraints to better characterize the atmospheric activity around InSight and in the region of Elysium Planitia, Mars.
    • Monitoring the Morphology of M87*in 2009-2017 with the Event Horizon Telescope

      Univ Arizona, Steward Observ; Univ Arizona, Dept Astron; Univ Arizona, Data Sci Inst (IOP PUBLISHING LTD, 2020)
      The Event Horizon Telescope (EHT) has recently delivered the first resolved images of M87*, the supermassive black hole in the center of the M87 galaxy. These images were produced using 230 GHz observations performed in 2017 April. Additional observations are required to investigate the persistence of the primary image feature-a ring with azimuthal brightness asymmetry-and to quantify the image variability on event horizon scales. To address this need, we analyze M87* data collected with prototype EHT arrays in 2009, 2011, 2012, and 2013. While these observations do not contain enough information to produce images, they are sufficient to constrain simple geometric models. We develop a modeling approach based on the framework utilized for the 2017 EHT data analysis and validate our procedures using synthetic data. Applying the same approach to the observational data sets, we find the M87* morphology in 2009-2017 to be consistent with a persistent asymmetric ring of similar to 40 mu as diameter. The position angle of the peak intensity varies in time. In particular, we find a significant difference between the position angle measured in 2013 and 2017. These variations are in broad agreement with predictions of a subset of general relativistic magnetohydrodynamic simulations. We show that quantifying the variability across multiple observational epochs has the potential to constrain the physical properties of the source, such as the accretion state or the black hole spin.
    • Monophasic action potential amplitude for substrate mapping

      Chinyere, Ikeotunye Royal; Hutchinson, Mathew; Moukabary, Talal; Lancaster, Jordan; Goldman, Steven; Juneman, Elizabeth; Univ Arizona, Sarver Heart Ctr; Univ Arizona, Coll Med (AMER PHYSIOLOGICAL SOC, 2019-10-01)
      Although radiofrequency ablation has revolutionized the management of tachyarrhythmias, the rate of arrhythmia recurrence is a large drawback. Successful substrate identification is paramount to abolishing arrhythmia, and bipolar voltage electrogram's narrow field of view can be further reduced for increased sensitivity. In this report, we perform cardiac mapping with monophasic action potential (MAP) amplitude. We hypothesize that MAP amplitude (MAPA) will provide more accurate infarct sizes than other mapping modalities via increased sensitivity to distinguish healthy myocardium from scar tissue. Using the left coronary artery ligation Sprague-Dawley rat model of ischemic heart failure, we investigate the accuracy of in vivo ventricular epicardial maps derived from MAPA, MAP duration to 90% repolarization (MAPD90), unipolar voltage amplitude (UVA), and bipolar voltage amplitude (BVA) compared with gold standard histopathological measurement of infarct size. Numerical analysis reveals discrimination of healthy myocardium versus scar tissue using MAPD90 (P = 0.0158) and UVA (P < 0.001, n = 21). MAPA and BVA decreased between healthy and border tissue (P = 0.0218 and 0.0015, respectively) and border and scar tissue (P = 0.0037 and 0.0094, respectively). Contrary to our hypothesis, BVA mapping performed most accurately regarding quantifying infarct size. MAPA mapping may have high spatial resolution for myocardial tissue characterization but was quantitatively less accurate than other mapping methods at determining infarct size. BVA mapping's superior utility has been reinforced, supporting its use in translational research and clinical electrophysiology laboratories. MAPA may hold potential value for precisely distinguishing healthy myocardium, border zone, and scar tissue in diseases of disseminated fibrosis such as atrial fibrillation. NEW & NOTEWORTHY Monophasic action potential mapping in a clinically relevant model of heart failure with potential implications for atrial fibrillation management.
    • Monopoles Loaded With 3-D-Printed Dielectrics for Future Wireless Intrachip Communications

      Wu, Junqiang; Kodi, Avinash Karanth; Kaya, Savas; Louri, Ahmed; Xin, Hao; Univ Arizona, Dept Elect & Comp Engn; Univ Arizona, Dept Phys (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017-12)
      We propose a novel antenna design enabled by 3-D printing technology for future wireless intrachip interconnects aiming at applications of multicore architectures and system-on-chips. In our proposed design we use vertical quarter-wavelength monopoles at 160 GHz on a ground plane to avoid low antenna radiation efficiency caused by the silicon substrate. The monopoles are surrounded by a specially designed dielectric property distribution. This additional degree of freedom in design enabled by 3-D printing technology is used to tailor the electromagnetic wave propagation. As a result, the desired wireless link gain is enhanced and the undesired spatial crosstalk is reduced. Simulation results show that the proposed dielectric loading approach improves the desired link gain by 8-15 dB and reduces the crosstalk by 9-23 dB from 155 to 165 GHz. As a proof-of-concept, a 60 GHz prototype is designed, fabricated, and characterized. Our measurement results match the simulation results and demonstrate 10-18 dB improvement of the desired link gain and 10-30 dB reduction in the crosstalk from 55 to 61 GHz. The demonstrated transmission loss of the desired link at a distance of 17 mm is only 15 dB, which is over 10 dB better than the previously reported work.
    • Monosialoganglioside-Containing Nanoliposomes Restore Endothelial Function Impaired by AL Amyloidosis Light Chain Proteins.

      Franco, Daniel A; Truran, Seth; Weissig, Volkmar; Guzman-Villanueva, Diana; Karamanova, Nina; Senapati, Subhadip; Burciu, Camelia; Ramirez-Alvarado, Marina; Blancas-Mejia, Luis M; Lindsay, Stuart; et al. (WILEY-BLACKWELL, 2016-06-13)
      Light chain amyloidosis (AL) is associated with high mortality, especially in patients with advanced cardiovascular involvement. It is caused by toxicity of misfolded light chain proteins (LC) in vascular, cardiac, and other tissues. There is no treatment to reverse LC tissue toxicity. We tested the hypothesis that nanoliposomes composed of monosialoganglioside, phosphatidylcholine, and cholesterol (GM1 ganglioside-containing nanoliposomes [NLGM1]) can protect against LC-induced human microvascular dysfunction and assess mechanisms behind the protective effect.