Now showing items 2473-2492 of 13388

    • Cotton leafroll dwarf virus us genomes comprise divergent subpopulations and harbor extensive variability

      Ramos-Sobrinho, R.; Adegbola, R.O.; Lawrence, K.; Schrimsher, D.W.; Isakeit, T.; Alabi, O.J.; Brown, J.K.; School of Plant Sciences, University of Arizona (MDPI, 2021)
      Cotton leafroll dwarf virus (CLRDV) was first reported in the United States (US) in 2017 from cotton plants in Alabama (AL) and has become widespread in cotton-growing states of the southern US. To investigate the genomic variability among CLRDV isolates in the US, complete genomes of the virus were obtained from infected cotton plants displaying mild to severe symptoms from AL, Florida, and Texas. Eight CLRDV genomes were determined, ranging in size from 5865 to 5867 bp, and shared highest nucleotide identity with other CLRDV isolates in the US, at 95.9–98.7%. Open reading frame (ORF) 0, encoding the P0 silencing suppressor, was the most variable gene, sharing 88.5–99.6% and 81.2–89.3% amino acid similarity with CLRDV isolates reported in cotton growing states in the US and in Argentina and Brazil in South America, respectively. Based on Bayesian analysis, the complete CLRDV genomes from cotton in the US formed a monophyletic group comprising three relatively divergent sister clades, whereas CLRDV genotypes from South America clustered as closely related sister-groups, separate from US isolates, patterns reminiscent of phylogeographical structuring. The CLRDV isolates exhibited a complex pattern of recombination, with most breakpoints evident in ORFs 2 and 3, and ORF5. Despite extensive nucleotide diversity among all available CLRDV genomes, purifying selection (dN/dS < 1) was implicated as the primary selective force acting on viral protein evolution. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
    • Cough Frequency During Treatment Associated With Baseline Cavitary Volume and Proximity to the Airway in Pulmonary TB.

      Proaño, Alvaro; Bui, David P; López, José W; Vu, Nancy M; Bravard, Marjory A; Lee, Gwenyth O; Tracey, Brian H; Xu, Ziyue; Comina, Germán; Ticona, Eduardo; et al. (ELSEVIER SCIENCE BV, 2018-06-01)
      Cough frequency, and its duration, is a biomarker that can be used in low-resource settings without the need of laboratory culture and has been associated with transmission and treatment response. Radiologic characteristics associated with increased cough frequency may be important in understanding transmission. The relationship between cough frequency and cavitary lung disease has not been studied. We analyzed data in 41 adults who were HIV negative and had culture-confirmed, drug-susceptible pulmonary TB throughout treatment. Cough recordings were based on the Cayetano Cough Monitor, and sputum samples were evaluated using microscopic observation drug susceptibility broth culture; among culture-positive samples, bacillary burden was assessed by means of time to positivity. CT scans were analyzed by a US-board-certified radiologist and a computer-automated algorithm. The algorithm evaluated cavity volume and cavitary proximity to the airway. CT scans were obtained within 1 month of treatment initiation. We compared small cavities (≤ 7 mL) and large cavities (> 7 mL) and cavities located closer to (≤ 10 mm) and farther from (> 10 mm) the airway to cough frequency and cough cessation until treatment day 60. Cough frequency during treatment was twofold higher in participants with large cavity volumes (rate ratio [RR], 1.98; P = .01) and cavities located closer to the airway (RR, 2.44; P = .001). Comparably, cough ceased three times faster in participants with smaller cavities (adjusted hazard ratio [HR], 2.89; P = .06) and those farther from the airway (adjusted HR, 3.61;, P = .02). Similar results were found for bacillary burden and culture conversion during treatment. Cough frequency during treatment is greater and lasts longer in patients with larger cavities, especially those closer to the airway.
    • Could two negative emotions be a positive? The effects of anger and anxiety in enemyship

      Motro, Daphna; Sullivan, Daniel; University of Arizona, Eller College of Management; University of Arizona, Department of Psychology (ACADEMIC PRESS INC ELSEVIER SCIENCE, 2017-03)
      Enemyship is an important but understudied interpersonal phenomenon. Prior research on this topic has focused on enemyship's cognitive, control-maintenance function following a threat. The present studies advance theory and research by showing the role of emotion, particularly anger, in this process. Using appraisal theory as a framework, we draw on recent research into approach and avoidance motivational dynamics during threat We propose an interaction between anxiety-inducing threat and enemy-directed anger on perceptions of control and certainty, and motivation. More specifically, we expect that when an anxiety-inducing threat is present, perceptions of control and certainty will be significantly higher when enemy-directed anger is also present than when it is not Additionally, we sought to demonstrate the consequences of these processes for motivation. Perhaps counterintuitively, we propose that individuals who experience anger at an enemy following an anxiety-inducing control threat will experience a boost in motivation, an effect mediated by perceptions of control and certainty. We find support for our moderated mediation model across three studies with undergraduate and working adults (Total N = 673).
    • Coulomb enhancement of superconducting pair-pair correlations in a 3 4 -filled model for κ − ( BEDT-TTF ) 2 X

      De Silva, W. Wasanthi; Gomes, N.; Mazumdar, S.; Clay, R. T.; Univ Arizona, Dept Phys (AMER PHYSICAL SOC, 2016-05-09)
      We present the results of precise correlated-electron calculations on the monomer lattices of the organic charge-transfer solids kappa-(BEDT-TTF)(2)X for 32 and 64 molecular sites. Our calculations are for band parameters corresponding to X = Cu[N(CN)(2)]Cl and Cu-2(CN)(3), which are semiconducting antiferromagnetic and quantum spin liquid, respectively, at ambient pressure. We have performed our calculations for variable electron densities. per BEDT-TTF molecule, with. ranging from 1 to 2. We find that d-wave superconducting pair-pair correlations are enhanced by electron-electron interactions only for a narrow carrier concentration about rho = 1.5, which is precisely the carrier concentration where superconductivity in the charge-transfer solids occurs. Our results indicate that the enhancement in pair-pair correlations is not related to antiferromagnetic order, but to a proximate hidden spin-singlet state that manifests itself as a charge-ordered state in other charge-transfer solids. Long-range superconducting order does not appear to be present in the purely electronic model, suggesting that electronphonon interactions also must play a role in a complete theory of superconductivity.
    • Council on Cardiovascular and Stroke Nursing Liaison Report: Pediatric Cardiovascular Nursing Committee

      Lambert, Linda M; Pike, Nancy A; Taylor-Piliae, Ruth E; Fink, Anne M; Univ Arizona, Coll Nursing (LIPPINCOTT WILLIAMS & WILKINS, 2020-09)
    • Counteracting Dark Web Text-Based CAPTCHA with Generative Adversarial Learning for Proactive Cyber Threat Intelligence

      Zhang, Ning; Ebrahimi, Mohammadreza; Li, Weifeng; Chen, Hsinchun; University of Arizona (Association for Computing Machinery (ACM), 2022-06-30)
      Automated monitoring of dark web (DW) platforms on a large scale is the first step toward developing proactive Cyber Threat Intelligence (CTI). While there are efficient methods for collecting data from the surface web, large-scale dark web data collection is often hindered by anti-crawling measures. In particular, text-based CAPTCHA serves as the most prevalent and prohibiting type of these measures in the dark web. Text-based CAPTCHA identifies and blocks automated crawlers by forcing the user to enter a combination of hard-to-recognize alphanumeric characters. In the dark web, CAPTCHA images are meticulously designed with additional background noise and variable character length to prevent automated CAPTCHA breaking. Existing automated CAPTCHA breaking methods have difficulties in overcoming these dark web challenges. As such, solving dark web text-based CAPTCHA has been relying heavily on human involvement, which is labor-intensive and time-consuming. In this study, we propose a novel framework for automated breaking of dark web CAPTCHA to facilitate dark web data collection. This framework encompasses a novel generative method to recognize dark web text-based CAPTCHA with noisy background and variable character length. To eliminate the need for human involvement, the proposed framework utilizes Generative Adversarial Network (GAN) to counteract dark web background noise and leverages an enhanced character segmentation algorithm to handle CAPTCHA images with variable character length. Our proposed framework, DW-GAN, was systematically evaluated on multiple dark web CAPTCHA testbeds. DW-GAN significantly outperformed the state-of-the-art benchmark methods on all datasets, achieving over 94.4% success rate on a carefully collected real-world dark web dataset. We further conducted a case study on an emergent Dark Net Marketplace (DNM) to demonstrate that DW-GAN eliminated human involvement by automatically solving CAPTCHA challenges with no more than three attempts. Our research enables the CTI community to develop advanced, large-scale dark web monitoring. We make DW-GAN code available to the community as an open-source tool in GitHub.
    • A country bug in the city: urban infestation by the Chagas disease vector Triatoma infestans in Arequipa, Peru

      Delgado, Stephen; Ernst, Kacey; Pumahuanca, Maria Luz; Yool, Stephen; Comrie, Andrew; Sterling, Charles; Gilman, Robert; Naquira, Cesar; Levy, Michael; the Chagas Disease Working Group, in Arequipa; et al. (BioMed Central, 2013)
      BACKGROUND:Interruption of vector-borne transmission of Trypanosoma cruzi remains an unrealized objective in many Latin American countries. The task of vector control is complicated by the emergence of vector insects in urban areas.METHODS:Utilizing data from a large-scale vector control program in Arequipa, Peru, we explored the spatial patterns of infestation by Triatoma infestans in an urban and peri-urban landscape. Multilevel logistic regression was utilized to assess the associations between household infestation and household- and locality-level socio-environmental measures.RESULTS:Of 37,229 households inspected for infestation, 6,982 (18.8%
    • County-level climate change information to support decision-making on working lands

      Elias, Emile; Schrader, T. Scott; Abatzoglou, John T.; James, Darren; Crimmins, Mike; Weiss, Jeremy; Rango, Albert; Univ Arizona, Dept Soil Water & Environm Sci, Tucson, AZ 85721 USA; Univ Arizona, Sch Nat Resources & Environm, Tucson, AZ 85721 USA (SPRINGER, 2018-06)
      Farmers, ranchers, and forest landowners across the USA make weather- and climate-related management decisions at varying temporal and spatial scales, often with input from local experts like crop consultants and cooperative extension (CE) personnel. In order to provide additional guidance to such longer-term planning efforts, we developed a tool that shows statistically downscaled climate projections of temperature and precipitation consolidated to the county level for the contiguous US. Using the county as a fundamental mapping unit encourages the use of this information within existing institutional structures like CE and other U.S. Department of Agriculture (USDA) programs. A "quick-look" metric based on the spatial variability of climate within each county aids in the interpretation of county-level information. For instance, relatively higher spatial variability within a county indicates that more localized information should be used to support stakeholder planning. Changes in annual precipitation show a latitudinal dipole where increases are projected for much of the northern US while declines are projected for counties across the southern US. Seasonal shifts in county-level precipitation are projected nationwide with declines most evident in summer months in most regions. Changes in the spatial variability of annual precipitation for most counties were less than 10 mm, indicating fairly spatially homogenous midcentury precipitation changes at the county level. Annual and seasonal midcentury temperatures are projected to increase across the USA, with relatively low change in the spatial variability (< 0.3 A degrees C) of temperature across most counties. The utility of these data is shown for forage and almond applications, both indicating a potential decline in production in some future years, to illustrate use of county-level seasonal projections in adaptation planning and decision-making.
    • Couple-Level Attachment Styles, Finances, and Marital Satisfaction: Mediational Analyses Among Young Adult Newlywed Couples

      Li, Xiaomin; Curran, Melissa A.; LeBaron-Black, Ashley B.; Jorgensen, Bryce; Yorgason, Jeremy; Wilmarth, Melissa J.; University of Arizona (Springer Science and Business Media LLC, 2021-11-17)
      Guided by attachment theory and the Vulnerability-Stress-Adaptation model, we used three-annual-wave, dyadic data from a nationally representative sample of 1136 young-adult newlywed couples to investigate two research aims. First, we conducted a Latent Profile Analysis to identify couple-level attachment styles at Time 1 (i.e., within the first 2 years of marriage) based on the combination of husbands’ and wives’ attachment anxiety and attachment avoidance. Second, after conceptualizing couple-level attachment styles at Time 1 as vulnerability, we then examined whether finance-specific adaptive processes at Time 2 (i.e., 1 year after Time 1) mediated associations from couple-level attachment styles at Time 1 to marital satisfaction at Time 3 (i.e., 1 year after Time 2). Several findings are noteworthy. First, four different types of couple-level attachment styles were found. Second, for mediators, only perceived partner financial mismanagement mediated associations from couple-level attachment styles at Time 1 to marital satisfaction at Time 3. We discuss how the four different couple-level styles highlight the diversity and complexity in how the two partners’ attachment anxiety and attachment avoidance combine together as well as why perceived partner financial mismanagement (i.e., the lack of adaptive processes) mediated associations between couple-level attachment styles and marital satisfaction.
    • Coupled Biospheric Synchrony of the Coastal Temperate Ecosystem in Northern Patagonia: A Remote Sensing Analysis

      Lara, Carlos; Cazelles, Bernard; Saldías, Gonzalo S.; Flores, Raúl P.; Paredes, Álvaro L.; Broitman, Bernardo R.; Univ Arizona, iGLOBE, UMI CNRS 3157 (MDPI, 2019-09-07)
      Over the last century, climate change has impacted the physiology, distribution, and phenology of marine and terrestrial primary producers worldwide. The study of these fluctuations has been hindered due to the complex response of plants to environmental forcing over large spatial and temporal scales. To bridge this gap, we investigated the synchrony in seasonal phenological activity between marine and terrestrial primary producers to environmental and climatic variability across northern Patagonia. We disentangled the effects on the biological activity of local processes using advanced time-frequency analysis and partial wavelet coherence on 15 years (2003–2017) of data from MODIS (Moderate Resolution Imaging Spectroradiometer) onboard the Terra and Aqua satellites and global climatic variability using large-scale climate indices. Our results show that periodic variations in both coastal ocean and land productivity are associated with sea surface temperature forcing over seasonal scales and with climatic forcing over multi-annual (2–4 years) modes. These complex relationships indicate that large-scale climatic processes primarily modulate the synchronous phenological seasonal activity across northern Patagonia, which makes these unique ecosystems highly exposed to future climatic change.
    • Coupled Evaluation of Below- and Aboveground Energy and Water Cycle Variables from Reanalysis Products over Five Flux Tower Sites in the United States

      Lytle, William; Zeng, Xubin; Univ Arizona, Dept Hydrol & Atmospher Sci (AMER METEOROLOGICAL SOC, 2016-07)
      Reanalysis products are widely used to study the land-atmosphere exchanges of energy, water, and carbon fluxes and have been evaluated using in situ data above or below ground. Here, measurements for several years at five flux tower sites in the United States (with a total of 315 576 h of data) are used for the coupled evaluation of both below-and aboveground processes from three global reanalysis products and six global land data assimilation products. All products show systematic errors in precipitation, snow depth, and the timing of the melting and onset of snow. Despite the biases in soil moisture, all products show significant correlations with observed daily soil moisture for the periods with unfrozen soil. While errors in 2-m air temperature are highly correlated with errors in skin temperature for all sites, the correlations between skin and soil temperature errors are weaker, particularly over the sites with seasonal snow. While net short-and longwave radiation flux errors have opposite signs across all products, the net radiation and ground heat flux errors are usually smaller in magnitude than turbulent flux errors. On the other hand, the all-product averages usually agree well with the observations on the evaporative fraction, defined as the ratio of latent heat over the sum of latent and sensible heat fluxes. This study identifies the strengths and weaknesses of these widely used products and helps understand the connection of their errors in above-versus belowground quantities.
    • Coupled Interannual Variability of Wind and Sea Surface Temperature in the Caribbean Sea and the Gulf of Mexico

      Rodriguez-Vera, Geidy; Romero-Centeno, Rosario; Castro, Christopher L.; Castro, Víctor Mendoza; Univ Arizona, Dept Hydrol & Atmospher Sci (AMER METEOROLOGICAL SOC, 2019-07)
      This work describes dominant patterns of coupled interannual variability of the 10-m wind and sea surface temperature in the Caribbean Sea and the Gulf of Mexico (CS&GM) during the period 1982-2016. Using a canonical correlation analysis (CCA) between the monthly mean anomalies of these fields, four coupled variability modes are identified: the dipole (March-April), transition (May-June), interocean (July-October), and meridional-wind (November-February) modes. Results show that El Nino-Southern Oscillation (ENSO) influences almost all the CS&GM coupled modes, except the transition mode, and that the North Atlantic Oscillation (NAO) in February has a strong negative correlation with the dipole and transition modes. The antisymmetric relationships found between the dipole mode and the NAO and ENSO indices confirm previous evidence about the competing remote forcings of both teleconnection patterns on the tropical North Atlantic variability. Precipitation in the CS and adjacent oceanic and land areas is sensitive to the wind-SST coupled variability modes from June to October. These modes seem to be strongly related to the interannual variability of the midsummer drought and the meridional migration of the intertropical convergence zone in the eastern Pacific. These findings may eventually lead to improving seasonal predictability in the CS&GM and surrounding land areas.
    • Coupled kinetic Boltzmann electromagnetic approach for intense ultrashort laser excitation of plasmonic nanostructures

      Rudenko, A.; Moloney, J.V.; Arizona Center for Mathematical Sciences, University of Arizona; College of Optical Sciences, University of Arizona (American Physical Society, 2021)
      We propose a multiphysical computational approach that allows for efficient coupling of full-vector Maxwell-based propagation codes with kinetic Boltzmann equations to investigate the spatial dynamics of non-equilibrium processes in plasmonic nanostructures upon intense laser excitation. Accessing the energy-resolved electron distribution provides a direct path towards multidimensional modeling of transient optical, electron emission, and electron transport processes. Simulations are performed for a gold nanoparticle upon infrared ultrashort-pulse excitation close to the melting threshold, evidencing the interplay between strong intrinsic and (non)thermal nonlinearities and accessing simultaneously the non-equilibrium thermal and propagation dynamics. While delivering the results within a reasonable simulation time and while being open to further extensions, the proposed approach can serve as a reliable compromise between point quantum and space-dimensional classical models. © 2021 American Physical Society.
    • A coupled microscopy approach to assess the nano-landscape of weathering

      Lybrand, Rebecca A; Austin, Jason C; Fedenko, Jennifer; Gallery, Rachel E; Rooney, Erin; Schroeder, Paul A; Zaharescu, Dragos G; Qafoku, Odeta; Univ Arizona, Sch Nat Resources & Environm; Univ Arizona, Dept Ecol & Evolutionary Biol (NATURE PUBLISHING GROUP, 2019-03-29)
      Mineral weathering is a balanced interplay among physical, chemical, and biological processes. Fundamental knowledge gaps exist in characterizing the biogeochemical mechanisms that transform microbe-mineral interfaces at submicron scales, particularly in complex field systems. Our objective was to develop methods targeting the nanoscale by using high-resolution microscopy to assess biological and geochemical drivers of weathering in natural settings. Basalt, granite, and quartz (53-250 mu m) were deployed in surface soils (10 cm) of three ecosystems (semiarid, subhumid, humid) for one year. We successfully developed a reference grid method to analyze individual grains using: (1) helium ion microscopy to capture micron to sub-nanometer imagery of mineral-organic interactions; and (2) scanning electron microscopy to quantify elemental distribution on the same surfaces via element mapping and point analyses. We detected locations of biomechanical weathering, secondary mineral precipitation, biofilm formation, and grain coatings across the three contrasting climates. To our knowledge, this is the first time these coupled microscopy techniques were applied in the earth and ecosystem sciences to assess microbe-mineral interfaces and in situ biological contributors to incipient weathering.
    • Coupled Modes of North Atlantic Ocean‐Atmosphere Variability and the Onset of the Little Ice Age

      Anchukaitis, Kevin J.; Cook, Edward R.; Cook, Benjamin I.; Pearl, Jessie; D'Arrigo, Rosanne; Wilson, Rob; Univ Arizona, Dept Geosci; Univ Arizona, Lab Tree Ring Res; Univ Arizona, Sch Geog & Dev (AMER GEOPHYSICAL UNION, 2019-11-07)
      Hydroclimate extremes in North America, Europe, and the Mediterranean are linked to ocean and atmospheric circulation anomalies in the Atlantic, but the limited length of the instrumental record prevents complete identification and characterization of these patterns of covariability especially at decadal to centennial time scales. Here we analyze the coupled patterns of drought variability on either sides of the North Atlantic Ocean basin using independent climate field reconstructions spanning the last millennium in order to detect and attribute epochs of coherent basin‐wide moisture anomalies to ocean and atmosphere processes. A leading mode of broad‐scale moisture variability is characterized by distinct patterns of North Atlantic atmosphere circulation and sea surface temperatures. We infer a negative phase of the North Atlantic Oscillation and colder Atlantic sea surface temperatures in the middle of the fifteenth century, coincident with weaker solar irradiance and prior to strong volcanic forcing associated with the early Little Ice Age.
    • Coupled Rapid Erosion and Foreland Sedimentation Control Orogenic Wedge Kinematics in the Himalayan Thrust Belt of Central Nepal

      DeCelles, P.G.; Carrapa, B.; Department of Geosciences, University of Arizona (Blackwell Publishing Ltd, 2021)
      Spatial and temporal coincidence among rapid Pliocene-Holocene bedrock exhumation, development of a topographic bight, abundant monsoonal precipitation, accumulation of anomalously thick proximal foreland basin deposits, and development of an opposite-polarity salient-reentrant couple on the two most frontal major thrust faults in the Himalayan orogenic wedge of central Nepal provide a basis for a model that links these diverse phenomena and could be operating in other parts of the frontal Himalaya. Rapid bedrock erosion is documented by a concentration of young (<5 Ma) low-temperature thermochronologic ages in the Narayani River catchment basin. Where the river exits the Lesser Himalayan Zone, the Main Boundary thrust has a 15-km-amplitude reentrant. Directly south of the reentrant lies the ∼50 km wide Chitwan wedge-top basin, which is confined by a large salient on the Main Frontal thrust. Rapid erosion and sediment flux out of the Narayani catchment basin, possibly due to anomalously intense monsoonal precipitation in this topographically depressed region of central Nepal, causes greater flexural subsidence and surface aggradation in the foreland, both of which increase initial wedge taper and render this region more susceptible to anomalous forward propagation of the thrust front. Analysis of the modern and post-early Miocene taper history of the thrust belt suggests that rapid erosion hindered forward propagation of the contemporaneous Main Boundary thrust, but simultaneously produced conditions in the foreland that eventually elevated initial taper to a critical/supercritical value promoting forelandward propagation of the Main Frontal thrust. This analysis has implications for large damaging earthquakes in the Himalaya. © 2021. American Geophysical Union. All Rights Reserved.
    • Coupling Between Lithosphere Removal and Mantle Flow in the Central Andes

      Wang, H.; Currie, C.A.; DeCelles, P.G.; Department of Geosciences, University of Arizona (John Wiley and Sons Inc, 2021)
      The central Andes is part of a Cordilleran orogen formed through continent-ocean convergence. In contrast to the thickened crust, the mantle lithosphere below much of the orogen is anomalously thin. Additionally, the surface is characterized by widespread backarc magmatism and transient ∼100-km-wide basins that developed the over last 30 million years, with basins located systematically seaward of major backarc ignimbrite centers and basin formation predating the late Miocene magma/ignimbrite flare-up. Using numerical models, we propose a novel mechanism whereby lithosphere removal is coupled with mantle flow. First, a small area of high-density eclogitized lower crust initiates a gravitational instability, causing a localized basin at the surface that subsides and then uplifts. Foundering crust and adjacent lithosphere are entrained by subduction-induced mantle flow, driving regional lithosphere removal and magmatism. The models demonstrate that mantle flow can amplify a local lithosphere instability to orogen-wide lithosphere removal, rapidly eliminating accumulated mass in the orogen. © 2021. American Geophysical Union. All Rights Reserved.
    • The Coupling of Peripheral Blood Pressure and Ventilatory Responses during Exercise in Young Adults with Cystic Fibrosis

      Van Iterson, Erik H.; Wheatley, Courtney M.; Baker, Sarah E.; Olson, Thomas P.; Morgan, Wayne J.; Snyder, Eric M.; Univ Arizona, Coll Pharm; Univ Arizona, Dept Pediat (PUBLIC LIBRARY SCIENCE, 2016-12-20)
      Purpose Cystic fibrosis (CF) is commonly recognized as a pulmonary disease associated with reduced airway function. Another primary symptom of CF is low exercise capacity where ventilation and gas-exchange are exacerbated. However, an independent link between pathophysiology of the pulmonary system and abnormal ventilatory and gas-exchange responses during cardiopulmonary exercise testing (CPET) has not been established in CF. Complicating this understanding, accumulating evidence suggests CF demonstrate abnormal peripheral vascular function; although, the clinical implications are unclear. We hypothesized that compared to controls, relative to total work performed (Work(TOT)), CF would demonstrate increased ventilation accompanied by augmented systolic blood pressure (SBP) during CPET. Methods 16 CF and 23 controls (age: 23 4 vs. 27 4 years, P = 0.11; FEV1%predicted: 73 14 vs. 96 5, P<0.01) participated in CPET. Breath-by-breath oxygen uptake (VO2), ventilation (VE), and carbon dioxide output (VCO2) were measured continuously during incremental 3-min stage step-wise cycle ergometry CPET. SBP was measured via manual sphygmomanometry. Linear regression was used to calculate V-E/VCO2 slope from rest to peak-exercise. Results Compared to controls, CF performed less WorkTOT during CPET (90 19 vs. 43 14 kJ, respectively, P<0.01). With Work(TOT) as a covariate, peak VE (62 8 vs. 90 4 L/min, P = 0.76), VCO2 (1.8 +/- 0.3 vs. 2.7 +/- 0.1 L/min, P = 0.40), and SBP (144 +/- 13 vs. 152 +/- 6 mmHg, P = 0.88) were similar between CF and controls, respectively; whereas CF demonstrated increased VE/VCO2 slope (38 4 vs. 28 2, P=0.02) but lower peak VO2 versus controls (22 +/- 5 vs. 33 +/- 4 mUkg/min, P<0.01). There were modest-to-moderate correlations between peak SBP with VO2 (r=0.30), V-E (r= 0.70), and VCO2 (r=0.62) in CF. Conclusions These data suggest that relative to Work(TOT), young adults with mild-to-moderate severity CF demonstrate augmented V-E/VCO2 slope accompanied by increased SBP during CPET. Although the underlying mechanisms remain unclear, the coupling of ventilatory inefficiency with increased blood pressure suggest important contributions from peripheral pathophysiology to low exercise capacity in CF.
    • Coupling of Tree Growth and Photosynthetic Carbon Uptake Across Six North American Forests

      Teets, A.; Moore, D.J.P.; Alexander, M.R.; Blanken, P.D.; Bohrer, G.; Burns, S.P.; Carbone, M.S.; Ducey, M.J.; Fraver, S.; Gough, C.M.; et al. (John Wiley and Sons Inc, 2022)
      Linking biometric measurements of stand-level biomass growth to tower-based measurements of carbon uptake—gross primary productivity and net ecosystem productivity—has been the focus of numerous ecosystem-level studies aimed to better understand the factors regulating carbon allocation to slow-turnover wood biomass pools. However, few of these studies have investigated the importance of previous year uptake to growth. We tested the relationship between wood biomass increment (WBI) and different temporal periods of carbon uptake from the current and previous years to investigate the potential lagged allocation of fixed carbon to growth among six mature, temperate forests. We found WBI was strongly correlated to carbon uptake across space (i.e., long-term averages at the different sites) but on annual timescales, WBI was much less related to carbon uptake, suggesting a temporal mismatch between C fixation and allocation to biomass. We detected lags in allocation of the previous year's carbon uptake to WBI at three of the six sites. Sites with higher annual WBI had overall stronger correlations to carbon uptake, with the strongest correlations to carbon uptake from the previous year. Only one site had WBI with strong positive relationships to current year uptake and not the previous year. Forests with low rates of WBI demonstrated weak correlations to carbon uptake from the previous year and stronger relationships to current year climate conditions. Our work shows an important, but not universal, role of lagged allocation of the previous year's carbon uptake to growth in temperate forests. © 2022. American Geophysical Union. All Rights Reserved.
    • Coupling plant litter quantity to a novel metric for litter quality explains C storage changes in a thawing permafrost peatland

      Hough, Moira; McCabe, Samantha; Vining, S Rose; Pickering Pedersen, Emily; Wilson, Rachel M; Lawrence, Ryan; Chang, Kuang-Yu; Bohrer, Gil; Riley, William J; Crill, Patrick M; et al. (Wiley, 2021-11-17)
      Permafrost thaw is a major potential feedback source to climate change as it can drive the increased release of greenhouse gases carbon dioxide (CO2 ) and methane (CH4 ). This carbon release from the decomposition of thawing soil organic material can be mitigated by increased net primary productivity (NPP) caused by warming, increasing atmospheric CO2 , and plant community transition. However, the net effect on C storage also depends on how these plant community changes alter plant litter quantity, quality, and decomposition rates. Predicting decomposition rates based on litter quality remains challenging, but a promising new way forward is to incorporate measures of the energetic favorability to soil microbes of plant biomass decomposition. We asked how the variation in one such measure, the nominal oxidation state of carbon (NOSC), interacts with changing quantities of plant material inputs to influence the net C balance of a thawing permafrost peatland. We found: (1) Plant productivity (NPP) increased post-thaw, but instead of contributing to increased standing biomass, it increased plant biomass turnover via increased litter inputs to soil; (2) Plant litter thermodynamic favorability (NOSC) and decomposition rate both increased post-thaw, despite limited changes in bulk C:N ratios; (3) these increases caused the higher NPP to cycle more rapidly through both plants and soil, contributing to higher CO2 and CH4  fluxes from decomposition. Thus, the increased C-storage expected from higher productivity was limited and the high global warming potential of CH4 contributed a net positive warming effect. Although post-thaw peatlands are currently C sinks due to high NPP offsetting high CO2 release, this status is very sensitive to the plant community's litter input rate and quality. Integration of novel bioavailability metrics based on litter chemistry, including NOSC, into studies of ecosystem dynamics, is needed to improve the understanding of controls on arctic C stocks under continued ecosystem transition.