Now showing items 1-20 of 8841

    • Dwarf Galaxy Discoveries from the KMTNet Supernova Program. II. The NGC 3585 Group and Its Dynamical State

      Park, Hong Soo; Moon, Dae-Sik; Zaritsky, Dennis; Kim, Sang Chul; Lee, Youngdae; Cha, Sang-Mok; Lee, Yongseok; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2019-11-01)
      We present our discovery and analysis of dwarf galaxies in the NGC 3585 galaxy group by the Korea Microlensing Telescope Network (KMTNet) Supernova Program. Using deep stack images reaching 28 mag arcsec(?2) in BVI, we discovered 46 dwarf galaxy candidates distributed in a field of 7 square degrees. The dwarf galaxy candidates exhibit a central surface brightness as faint as ?(0,V)=26.2 mag arcsec(?2), with effective radii larger than 150 pc and total absolute magnitudes brighter than M-V?10 mag, if at the distance of NGC 3585. The dwarf galaxy surface number density decreases with projected distance from NGC 3585. We estimate the background contamination to be about 20% based both on the number density profile and on diffuse galaxy counts in a control field. The dwarf galaxy colors and Srsic structural parameters are consistent with those found for other dwarf galaxies. Unusually, there is no indication of a change in color or brightness in the dwarf galaxy candidates with projected distance from the group center. Approximately 20% of the candidates contain an unresolved nucleus. The nucleated fraction is larger for brighter (and redder) galaxies, but is independent of distance from the group center. We identify four ultra-diffuse galaxy candidates, all near the group center. We interpret these spatial properties as suggesting that the NGC 3585 group might be dynamically younger than the typical group. The galaxy luminosity function of the NGC 3585 group has a faint-end slope of ??1.39, which is roughly consistent with the slopes found for other nearby groups. The possible dependence of the slope on global group properties is still unclear and continues to motivate our homogeneous deep survey of dozens of nearby groups.
    • Demographics of Planetesimals Formed by the Streaming Instability

      Li, Rixin; Youdin, Andrew N.; Simon, Jacob B.; Univ Arizona, Steward Observ; Univ Arizona, Dept Astron (IOP PUBLISHING LTD, 2019-10-31)
      The streaming instability (SI) is a mechanism to aerodynamically concentrate solids in protoplanetary disks and facilitate the formation of planetesimals. Recent numerical modeling efforts have demonstrated the increasing complexity of the initial mass distribution of planetesimals. To better constrain this distribution, we conduct SI simulations including self-gravity with the highest resolution hitherto. To subsequently identify all of the self-bound clumps, we develop a new clump-finding tool, Planetesimal Analyzer. We then apply a maximum likelihood estimator to fit a suite of parameterized models with different levels of complexity to the simulated mass distribution. To determine which models are best-fitting and statistically robust, we apply three model selection criteria with different complexity penalties. We find that the initial mass distribution of clumps is not universal regarding both the functional forms and parameter values. Our model selection criteria prefer models different from those previously considered in the literature. Fits to multi-segment power-law models break to a steeper distribution above masses close to those of 100 km collapsed planetesimals, similar to observed size distributions in the Kuiper Belt. We find evidence for a turnover at the low-mass end of the planetesimal mass distribution in our high-resolution run. Such a turnover is expected for gravitational collapse, but had not previously been reported.
    • Tracking Dust Grains during Transport and Growth in Protoplanetary Disks

      Misener, William; Krijt, Sebastiaan; Ciesla, Fred J.; Univ Arizona, Dept Astron, Steward Observ (IOP PUBLISHING LTD, 2019-11-07)
      Protoplanetary disks are dynamic objects, within which dust grains and gas are expected to be redistributed over large distances. Evidence for this redistribution is seen both in other protoplanetary disks and in our own solar system, with high-temperature materials thought to originate close to the central star found in the cold, outer regions of the disks. While models have shown this redistribution is possible through a variety of mechanisms, these models have generally ignored the possible growth of solids via grain–grain collisions that would occur during transit. Here we investigate the interplay of coagulation and radial and vertical transport of solids in protoplanetary disks, considering cases where growth is limited by bouncing or by fragmentation. We find that, in all cases, growth effectively limits the facility for materials to be carried outward or preserved at large distances from the star. This is due to solids being incorporated into large aggregates which drift inward rapidly under the effects of gas drag. We discuss the implications for mixing in protoplanetary disks, and how the preservation of high-temperature materials in outer disks may require structures or outward flow patterns to avoid them being lost via radial drift.
    • Fluorine Abundances in the Galactic Disk

      Guerço, Rafael; Cunha, Katia; Smith, Verne V.; Hayes, Christian R.; Abia, Carlos; Lambert, David L.; Jönsson, Henrik; Ryde, Nils; Univ Arizona (IOP PUBLISHING LTD, 2019-11-08)
      The chemical evolution of fluorine is investigated in a sample of Milky Way red giant stars that span a significant range in metallicity from [Fe/H] ? ?1.3 to 0.0 dex. Fluorine abundances are derived from vibration-rotation lines of HF in high-resolution infrared spectra near 2.335 ?m. The red giants are members of the thin and thick disk/halo, with two stars being likely members of the outer disk Monoceros overdensity. At lower metallicities, with [Fe/H] < ?0.4 to ?0.5, the abundance of F varies as a primary element with respect to the Fe abundance, with a constant subsolar value of [F/Fe] ? ?0.3 to ?0.4 dex. At larger metallicities, however, [F/Fe] increases rapidly with [Fe/H] and displays a near-secondary behavior with respect to Fe. Comparisons with various models of chemical evolution suggest that in the low-metallicity regime (dominated here by thick-disk stars), a primary evolution of F-19 with Fe, with a subsolar [F/Fe] value that roughly matches the observed plateau, can be reproduced by a model incorporating neutrino nucleosynthesis in the aftermath of the core collapse in Type II supernovae. A primary behavior for [F/Fe] at low metallicity is also observed for a model including rapidly rotating low-metallicity massive stars, but this overproduces [F/Fe] at low metallicity. The thick-disk red giants in our sample span a large range of galactocentric distance (R-g ? 6?13.7 kpc) yet display a roughly constant value of [F/Fe], indicating a very flat gradient (with a slope of 0.02 0.03 dex kpc(?1)) of this elemental ratio over a significant portion of the Galaxy having ?Z? 300 pc away from the Galaxy midplane.
    • Ant-plant mutualism: a dietary by-product of a tropical ant's macronutrient requirements

      Arcila Hernández, Lina M; Sanders, Jon G; Miller, Gabriel A; Ravenscraft, Alison; Frederickson, Megan E; Univ Arizona, Ctr Insect Sci (WILEY-BLACKWELL, 2017-10-04)
      Many arboreal ants depend on myrmecophytic plants for both food and shelter; in return, these ants defend their host plants against herbivores, which are often insects. Ant–plant and other mutualisms do not necessarily involve the exchange of costly rewards or services; they may instead result from by‐product benefits, or positive outcomes that do not entail a cost for one or both partners. Here, we examined whether the plant‐ant Allomerus octoarticulatus pays a short‐term cost to defend their host plants against herbivores, or whether plant defense is a by‐product benefit of ant foraging for insect prey. Because the food offered by ant‐plants is usually nitrogen‐poor, arboreal ants may balance their diets by consuming insect prey or associating with microbial symbionts to acquire nitrogen, potentially shifting the costs and benefits of plant defense for the ant partner. To determine the effect of ant diet on an ant–plant mutualism, we compared the behavior, morphology, fitness, stable isotope signatures, and gaster microbiomes of A. octoarticulatus ants nesting in Cordia nodosa trees maintained for nearly a year with or without insect herbivores. At the end of the experiment, ants from herbivore exclosures preferred protein‐rich baits more than ants in the control (i.e., herbivores present) treatment. Furthermore, workers in the control treatment were heavier than in the herbivore‐exclusion treatment, and worker mass predicted reproductive output, suggesting that foraging for insect prey directly increased ant colony fitness. The gaster microbiome of ants was not significantly affected by the herbivore exclusion treatment. We conclude that the defensive behavior of some phytoecious ants is a by‐product of their need for external protein sources; thus, the consumption of insect herbivores by ants benefits both the ant colony and the host plant.
    • The relationship between direct predation and antipredator responses: a test with multiple predators and multiple prey

      Creel, Scott; Dröge, Egil; M'soka, Jassiel; Smit, Daan; Becker, Matt; Christianson, Dave; Schuette, Paul; Univ Arizona, Sch Nat Resources & Environm (WILEY-BLACKWELL, 2017-05-05)
      Most species adjust their behavior to reduce the likelihood of predation. Many experiments have shown that antipredator responses carry energetic costs that can affect growth, survival, and reproduction, so that the total cost of predation depends on a trade‐off between direct predation and risk effects. Despite these patterns, few field studies have examined the relationship between direct predation and the strength of antipredator responses, particularly for complete guilds of predators and prey. We used scan sampling in 344 observation periods over a four‐year field study to examine behavioral responses to the immediate presence of predators for a complete antelope guild (dominated by wildebeest, zebra, and oribi) in Liuwa Plains National Park, Zambia, testing for differences in response to all large carnivores in the ecosystem (lions, spotted hyenas, cheetahs, and African wild dogs). We quantified the proportion that each prey species contributed to the kills made by each predator (516 total kills), used distance sampling on systematic line transects to determine the abundance of each prey species, and combined these data to quantify the per‐capita risk of direct predation for each predator–prey pair. On average, antelopes increased their vigilance by a factor of 2.4 when predators were present. Vigilance varied strongly among prey species, but weakly in response to different predators. Increased vigilance was correlated with reduced foraging in a similar manner for all prey species. The strength of antipredator response was not detectably related to patterns of direct predation (n = 15 predator–prey combinations with sufficient data). This lack of correlation has implications for our understanding of the role of risk effects as part of the limiting effect of predators on prey.
    • The Mass and Size Distribution of Planetesimals Formed by the Streaming Instability. II. The Effect of the Radial Gas Pressure Gradient

      Abod, Charles P.; Simon, Jacob B.; Li, Rixin; Armitage, Philip J.; Youdin, Andrew N.; Kretke, Katherine A.; Univ Arizona, Dept Astron; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2019-10-04)
      The streaming instability concentrates solid particles in protoplanetary disks, leading to gravitational collapse into planetesimals. Despite its key role in producing particle clumping and determining critical length scales in the instability's linear regime, the influence of the disk's radial pressure gradient on planetesimal properties has not been examined in detail. Here, we use streaming instability simulations that include particle self-gravity to study how the planetesimal initial mass function depends on the radial pressure gradient. Fitting our results to a power law, dN/dM(p) proportional to M-p(-p), we find that a single value p approximate to 1.6 describes simulations in which the pressure gradient varies by greater than or similar to 2. An exponentially truncated power law provides a significantly better fit, with a low-mass slope of p' approximate to 1.3 that weakly depends on the pressure gradient. The characteristic truncation mass is found to be similar to M-G = 4 pi(5)G(2)Sigma(3)(p)/Omega(4). We exclude the cubic dependence of the characteristic mass with pressure gradient suggested by linear considerations, finding instead a linear scaling. These results strengthen the case for a streaming-derived initial mass function that depends at most weakly on the aerodynamic properties of the disk and participating solids. A simulation initialized with zero pressure gradient-which is not subject to the streaming instability-also yields a top-heavy mass function but with modest evidence for a different shape. We discuss the consistency of the theoretically predicted mass function with observations of Kuiper Belt planetesimals, and describe implications for models of early-stage planet formation.
    • Biogeochemistry drives diversity in the prokaryotes, fungi, and invertebrates of a Panama forest

      Kaspari, Michael; Bujan, Jelena; Weiser, Michael D.; Ning, Daliang; Michaletz, Sean T.; Zhili, He; Enquist, Brian J.; Waide, Robert B.; Zhou, Jizhong; Turner, Benjamin L.; et al. (WILEY-BLACKWELL, 2017-05-13)
      Humans are both fertilizing the world and depleting its soils, decreasing the diversity of aquatic ecosystems and terrestrial plants in the process. We know less about how nutrients shape the abundance and diversity of the prokaryotes, fungi, and invertebrates of Earth's soils. Here we explore this question in the soils of a Panama forest subject to a 13‐yr fertilization with factorial combinations of nitrogen (N), phosphorus (P), and potassium (K) and a separate micronutrient cocktail. We contrast three hypotheses linking biogeochemistry to abundance and diversity. Consistent with the Stress Hypothesis, adding N suppressed the abundance of invertebrates and the richness of all three groups of organisms by ca. 1 SD or more below controls. Nitrogen addition plots were 0.8 pH units more acidic with 18% more exchangeable aluminum, which is toxic to both prokaryotes and eukaryotes. These stress effects were frequently reversed, however, when N was added with P (for prokaryotes and invertebrates) and with added K (for fungi). Consistent with the Abundance Hypothesis, adding P generally increased prokaryote and invertebrate diversity, and adding K enhanced invertebrate diversity. Also consistent with the Abundance Hypothesis, increases in invertebrate abundance generated increases in richness. We found little evidence for the Competition Hypothesis: that single nutrients suppressed diversity by favoring a subset of high nutrient specialists, and that nutrient combinations suppressed diversity even more. Instead, combinations of nutrients, and especially the cation/micronutrient treatment, yielded the largest increases in richness in the two eukaryote groups. In sum, changes in soil biogeochemistry revealed a diversity of responses among the three dominant soil groups, positive synergies among nutrients, and–in contrast with terrestrial plants–the frequent enhancement of soil biodiversity.
    • Predicting trait-environment relationships for venation networks along an Andes-Amazon elevation gradient

      Blonder, Benjamin; Salinas, Norma; Patrick Bentley, Lisa; Shenkin, Alexander; Chambi Porroa, Percy O; Valdez Tejeira, Yolvi; Violle, Cyrille; Fyllas, Nikolaos M; Goldsmith, Gregory R; Martin, Robert E; et al. (WILEY-BLACKWELL, 2017-01-25)
      Understanding functional trait‐environment relationships (TERs) may improve predictions of community assembly. However, many empirical TERs have been weak or lacking conceptual foundation. TERs based on leaf venation networks may better link individuals and communities via hydraulic constraints. We report measurements of vein density, vein radius, and leaf thickness for more than 100 dominant species occurring in ten forest communities spanning a 3,300 m Andes‐Amazon elevation gradient in Peru. We use these data to measure the strength of TERs at community scale and to determine whether observed TERs are similar to those predicted by physiological theory. We found strong support for TERs between all traits and temperature, as well weaker support for a predicted TER between maximum abundance‐weighted leaf transpiration rate and maximum potential evapotranspiration. These results provide one approach for developing a more mechanistic trait‐based community assembly theory.
    • Particle Acceleration at the Pileup Collision of the Twin Shock

      Wang, Xin; Giacalone, Joe; Yan, Yihua; Ding, Mingde; Li, Chuan; Lu, Hong; Shan, Hao; Univ Arizona, Lunar & Planetary Lab (IOP PUBLISHING LTD, 2019-10-31)
      Ground-level enhancement (GLE) events are often associated with large gradual solar events such as fast coronal mass ejections (CMEs), but not all fast CMEs lead to GLE events. Is there a type of coordinated CME that could produce GLEs with larger intensity and higher energies than those in the normal fast isolated CMEs? Here we propose a twin-shock scenario driven by the twin CME coordinately, in which the posterior shock catches up with the preceding shock and has a pileup collision. In the present study, we chose the first GLE event of the solar cycle 24 occurring on 2012 May 17 as an example to investigate the probable association with the twin-shock scenario. We use a dynamic Monte Carlo method to examine the energy spectrum with relevance to the GLE event. In the twin-shock scenario, the seed energetic particles produced by the normal preceding shock can be injected into the posterior shock for reacceleration efficiently. As a result, we obtain the detailed energy spectrum of the solar energetic particles (SEPs) with different behaviors at the related episodes of the twin-shock evolution. Therefore, we predict that the pileup collision of the twin shock would dominate a concave energy spectral slope in the 2012 May 17 SEP event.
    • Measurement of W-+/--boson and Z-boson production cross-sections in pp collisions at root s=2.76 TeV with the ATLAS detector

      Berlendis, S; Cheu, E; Delitzsch, C M; Johns, K A; Jones, S; Lampl, W; LeBlanc, M; Leone, R; Loch, P; Nayyar, R; et al. (SPRINGER, 2019-11-08)
      The production cross-sections for W +/- and Z bosons are measured using ATLAS data corresponding to an integrated luminosity of 4.0 pb-1 collected at a centre-ofmass energy v s = 2.76 TeV. The decay channels W and Z. are used, where can be an electron or a muon. The cross-sections are presented for a fiducial region defined by the detector acceptance and are also extrapolated to the full phase space for the total inclusive production cross-section. The combined (average) total inclusive cross-sections for the electron and muon channels are: s tot W+ = 2312 +/- 26 (stat.) +/- 27 (syst.) +/- 72 (lumi.) +/- 30 (extr.) pb, s tot W- = 1399 +/- 21 (stat.) +/- 17 (syst.) +/- 43 (lumi.) +/- 21 (extr.) pb, s tot Z. = 323.4 +/- 9.8 (stat.) +/- 5.0 (syst.) +/- 10.0 (lumi.) +/- 5.5(extr.) pb. Measured ratios and asymmetries constructed using these cross-sections are also presented. These observables benefit from full or partial cancellation of many systematic uncertainties that are correlated between the different measurements.
    • Evidence for the production of three massive vector bosons with the ATLAS detector

      Berlendis, S; Cheu, E; Delitzsch, C M; Johns, K A; Jones, S; Lampl, W; LeBlanc, M; Leone, R; Loch, P; Rutherfoord, J P; et al. (ELSEVIER, 2019-09-10)
      A search for the production of three massive vector bosons in proton-proton collisions is performed using data at root s = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider in the years 2015-2017 corresponding to an integrated luminosity of 79.8 fb(-1). Events with two same-sign leptons l (electrons or muons) and at least two reconstructed jets are selected to search for WWW -> l nu l nu qq. Events with three leptons without any same-flavour opposite-sign lepton pairs are used to search for WWW > l nu l nu l nu while events with three leptons and at least one same-flavour opposite-sign lepton pair and one or more reconstructed jets are used to search for WWZ -> l nu qqll. Finally events with four leptons are analysed to search for WWZ > l nu l nu ll and WZZ > qqllll. Evidence for the joint production of three massive vector bosons is observed with a significance of 4.1 standard deviations where the expectation is 3.1 standard deviations. (C) 2019 The Author(s). Published by Elsevier B.V.
    • Transcriptomic and evolutionary analysis of the mechanisms by which P. argentatum, a rubber producing perennial, responds to drought

      Nelson, Andrew D L; Ponciano, Grisel; McMahan, Colleen; Ilut, Daniel C; Pugh, N Ace; Elshikha, Diaa Eldin; Hunsaker, Douglas J; Pauli, Duke; Univ Arizona, Sch Plant Sci; Univ Arizona, Biosyst Engn (BMC, 2019-11-13)
      Background Guayule (Parthenium argentatum Gray) is a drought tolerant, rubber producing perennial shrub native to northern Mexico and the US Southwest. Hevea brasiliensis, currently the world's only source of natural rubber, is grown as a monoculture, leaving it vulnerable to both biotic and abiotic stressors. Isolation of rubber from guayule occurs by mechanical harvesting of the entire plant. It has been reported that environmental conditions leading up to harvest have a profound impact on rubber yield. The link between rubber biosynthesis and drought, a common environmental condition in guayule's native habitat, is currently unclear. Results We took a transcriptomic and comparative genomic approach to determine how drought impacts rubber biosynthesis in guayule. We compared transcriptional profiles of stem tissue, the location of guayule rubber biosynthesis, collected from field-grown plants subjected to water-deficit (drought) and well-watered (control) conditions. Plants subjected to the imposed drought conditions displayed an increase in production of transcripts associated with defense responses and water homeostasis, and a decrease in transcripts associated with rubber biosynthesis. An evolutionary and comparative analysis of stress-response transcripts suggests that more anciently duplicated transcripts shared among the Asteraceae, rather than recently derived duplicates, are contributing to the drought response observed in guayule. In addition, we identified several deeply conserved long non-coding RNAs (lncRNAs) containing microRNA binding motifs. One lncRNA in particular, with origins at the base of Asteraceae, may be regulating the vegetative to reproductive transition observed in water-stressed guayule by acting as a miRNA sponge for miR166. Conclusions These data represent the first genomic analyses of how guayule responds to drought like conditions in agricultural production settings. We identified an inverse relationship between stress-responsive transcripts and those associated with precursor pathways to rubber biosynthesis suggesting a physiological trade-off between maintaining homeostasis and plant productivity. We also identify a number of regulators of abiotic responses, including transcription factors and lncRNAs, that are strong candidates for future projects aimed at modulating rubber biosynthesis under water-limiting conditions common to guayules' native production environment.
    • Measurement of the production cross section for a Higgs boson in association with a vector boson in the H -> WW* -> l nu l nu channel in pp collisions at root s=13 TeV with the ATLAS detector

      Berlendis, S; Cheu, E; Delitzsch, C M; Johns, K A; Jones, S; Lampl, W; LeBlanc, M; Leone, R; Loch, P; Rutherfoord, J P; et al. (ELSEVIER, 2019-09-23)
      A measurement of the Higgs boson production cross sections via associated WH and ZH production using H -> WW* -> l nu l nu decays, where l stands for either an electron or a muon, is presented. Results for combined WH and ZH production are also presented. The analysis uses events produced in proton-proton collisions collected with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The data correspond to an integrated luminosity of 36.1 fb(-1) recorded at a centre-of-mass energy of 13 TeV. The products of the H -> WW* branching fraction times the WH and ZH cross sections are measured to be 0.67(-0.27)(+0.31)(stat.)(-0.14)(+0.18)(syst.) pb and 0.54(-0.24)(+0.31)(stat.)(-0.07)(+0.15)(syst.) pb respectively, in agreement with the Standard Model predictions. (C) 2019 The Author(s). Published by Elsevier B.V.
    • Gendered Spaces, Gendered Friendship Networks? Exploring the Organizing Patterns of LGBTQ Youth

      Gillig, Traci K; Bighash, Leila; Univ Arizona (USC ANNENBERG PRESS, 2019)
      Research has found a tendency for youth to develop friendships with same-gender peers. Whether this is due to a preference for same-gender friends or is an outcome of communication constraints from gender-segregated physical spaces and social practices is unclear. The current study is among the first to examine the role of emerging gender-inclusive spaces in adolescent friendship network patterns. A network of 111 LGBTQ adolescents interacting in a summer camp featuring gender-inclusive housing is examined using social network analysis techniques. Exponential random graph models found that campers’ assigned cabin was significantly related to friendship ties. Notably, the probability of a friendship tie was approximately 6 times greater when campers were assigned to the same cabin. Gender identity and birth sex had no significant influence on friendship patterns, in contrast to prior studies. Our findings highlight the potential for gender-inclusive spaces to integrate youth’s friendships across gender identities.
    • Use of a Fully Automated Internet-Based Cognitive Behavior Therapy Intervention in a Community Population of Adults With Depression Symptoms: Randomized Controlled Trial

      Schure, Mark B; Lindow, Janet C; Greist, John H; Nakonezny, Paul A; Bailey, Sandra J; Bryan, William L; Byerly, Matthew J; Univ Arizona, Coll Med, Dept Psychiat (JMIR PUBLICATIONS, INC, 2019-11-16)
      Background: Although internet-based cognitive behavior therapy (iCBT) interventions can reduce depression symptoms, large differences in their effectiveness exist. Objective: The aim of this study was to evaluate the effectiveness of an iCBT intervention called Thrive, which was designed to enhance engagement when delivered as a fully automated, stand-alone intervention to a rural community population of adults with depression symptoms. Methods: Using no diagnostic or treatment exclusions, 343 adults with depression symptoms were recruited from communities using an open-access website and randomized 1:1 to the Thrive intervention group or the control group. Using self-reports, participants were evaluated at baseline and 4 and 8 weeks for the primary outcome of depression symptom severity and secondary outcome measures of anxiety symptoms, work and social adjustment, psychological resilience, and suicidal ideation. Results: Over the 8-week follow-up period, the intervention group (n=181) had significantly lower depression symptom severity than the control group (n=162; P<.001), with a moderate treatment effect size (d=0.63). Moderate to near-moderate effect sizes favoring the intervention group were observed for anxiety symptoms (P<.001; d=0.47), work/social functioning (P<.001; d=0.39), and resilience (P<.001; d=0.55). Although not significant, the intervention group was 45% less likely than the control group to experience increased suicidal ideation (odds ratio 0.55). Conclusions: These findings suggest that the Thrive intervention was effective in reducing depression and anxiety symptom severity and improving functioning and resilience among a mostly rural community population of US adults. The effect sizes associated with Thrive were generally larger than those of other iCBT interventions delivered as a fully automated, stand-alone intervention.
    • Seasonality and predictability shape temporal species diversity

      Tonkin, Jonathan D; Bogan, Michael T; Bonada, Núria; Rios-Touma, Blanca; Lytle, David A; Univ Arizona, Sch Nat Resources & Environm (WILEY-BLACKWELL, 2017-01-31)
      Temporal environmental fluctuations, such as seasonality, exert strong controls on biodiversity. While the effects of seasonality are well known, the predictability of fluctuations across years may influence seasonality in ways that are less well understood. The ability of a habitat to support unique, non‐nested assemblages of species at different times of the year should depend on both seasonality (occurrence of events at specific periods of the year) and predictability (the reliability of event recurrence) of characteristic ecological conditions. Drawing on tools from wavelet analysis and information theory, we developed a framework for quantifying both seasonality and predictability of habitats, and applied this using global long‐term rainfall data. Our analysis predicted that temporal beta diversity should be maximized in highly predictable and highly seasonal climates, and that low degrees of seasonality, predictability, or both would lower diversity in characteristic ways. Using stream invertebrate communities as a case study, we demonstrated that temporal species diversity, as exhibited by community turnover, was determined by a balance between temporal environmental variability (seasonality) and the reliability of this variability (predictability). Communities in highly seasonal mediterranean environments exhibited strong oscillations in community structure, with turnover from one unique community type to another across seasons, whereas communities in aseasonal New Zealand environments fluctuated randomly. Understanding the influence of seasonal and other temporal scales of environmental oscillations on diversity is not complete without a clear understanding of their predictability, and our framework provides tools for examining these trends at a variety of temporal scales, seasonal and beyond. Given the uncertainty of future climates, seasonality and predictability are critical considerations for both basic science and management of ecosystems (e.g., dam operations, bioassessment) spanning gradients of climatic variability.
    • OSSOS. XVIII. Constraining Migration Models with the 2:1 Resonance Using the Outer Solar System Origins Survey

      Chen, Ying-Tung; Gladman, Brett; Volk, Kathryn; Murray-Clay, Ruth; Lehner, Matthew J.; Kavelaars, J. J.; Wang, Shiang-Yu; Lin, Hsing-Wen; Lykawka, Patryk Sofia; Alexandersen, Mike; et al. (IOP PUBLISHING LTD, 2019-11-01)
      Resonant dynamics plays a significant role in the past evolution and current state of our outer solar system. The population ratios and spatial distribution of Neptune?s resonant populations are direct clues to understanding the history of our planetary system. The orbital structure of the objects in Neptune?s 2:1 mean-motion resonance ("twotinos") has the potential to be a tracer of planetary migration processes. Different migration processes produce distinct architectures, recognizable by well-characterized surveys. However, previous characterized surveys only discovered a few twotinos, making it impossible to model the intrinsic twotino population. With a well-designed cadence and nearly 100% tracking success, the Outer Solar System Origins Survey (OSSOS) discovered 838 trans-Neptunian objects, of which 34 are securely twotinos with well-constrained libration angles and amplitudes. We use the OSSOS twotinos and the survey characterization parameters via the OSSOS survey simulator to inspect the intrinsic population and orbital distributions of twotinos. The estimated twotino population, 8.66 (diameter ?100 km) at 95% confidence, is consistent with the previous low-precision estimate. We also constrain the width of the inclination distribution to a relatively narrow value of 0.275 with a width 0.06. We find a single-slope exponential luminosity function with 0.6 for the twotinos. Finally, for the first time, we meaningfully constrain the fraction of symmetric twotinos and the ratio of the leading asymmetric islands; both fractions are in the range of 0.2?0.6. These measurements rule out certain theoretical models of Neptune's migration history.
    • Invasive Cardiac Procedures in Interstage Single Ventricle Patients in Emergent Hospitalizations

      Haughey, Brena S; White, Shelby C; Pacheco, Garrett S; Fox, Kenneth A; Seckeler, Michael D; Univ Arizona, Dept Pediat; Univ Arizona, Dept Pediat Cardiol; Univ Arizona, Dept Emergency Med; Univ Arizona, Dept Surg Pediat Cardiothorac (SPRINGER, 2019-11-08)
      Single ventricle congenital heart disease (SV CHD) patients are at risk of morbidity and mortality between the first and second palliative surgical procedures (interstage). When these patients present acutely they often require invasive intervention. This study sought to compare the outcomes and costs of elective and emergent invasive cardiac procedures for interstage patients. Retrospective review of discharge data from The Vizient Clinical Data Base/Resource Manager™, a national health care analytics platform. The database was queried for admissions from 10/2014 to 12/2017 for children 1-6 months old with ICD-9 or ICD-10 codes for SV CHD who underwent invasive cardiac procedures. Demographics, length of stay (LOS), complication rate, in-hospital mortality and direct costs were compared between elective and emergent admissions using t test or χ2, as appropriate. The three most frequently performed procedures were also compared. 871 admissions identified, with 141 (16%) emergent. Age of emergent admission was younger than elective (2.9 vs. 4 months p < 0.001). Emergent admissions including cardiac catheterization or superior cavo-pulmonary anastomosis had longer LOS (58.7 vs. 25.8 day, p < 0.001 and 54.8 vs .22.6 days, p < 0.001) and higher costs ($134,774 vs. $84,253, p = 0.013 and $158,679 vs. $81,899, p = 0.017). Emergent admissions for interstage SV CHD patients undergoing cardiac catheterization or superior cavo-pulmonary anastomosis are associated with longer LOS and higher direct costs, but with no differences in complications or mortality. These findings support aggressive interstage monitoring to minimize the need for emergent interventions for this fragile patient population.
    • Does feedback matter for job search self‐regulation? It depends on feedback quality

      Chawla, Nitya; Gabriel, Allison S.; da Motta Veiga, Serge P.; Slaughter, Jerel E.; Univ Arizona, Dept Management & Org, Eller Coll Management (WILEY, 2019-02-20)
      Job search represents a dynamic process through which job seekers must consistently engage in effective self‐regulation. Although scholars have increasingly begun to theorize and conceptualize the job search in this manner, little is known about what fosters effective self‐regulation week‐to‐week. In light of this theoretical gap, we integrate self‐regulation theory with the feedback literature to examine how feedback quality influences affective, cognitive, and behavioral regulatory processes in job search. Furthermore, we examine feedback self‐efficacy (i.e., how efficacious a job seeker feels with respect to processing and implementing feedback received during the job search) as a stable, person‐level moderator of these within‐person relationships. In a sample of job seekers surveyed once a week for seven weeks, results indicate that receiving high‐quality feedback has a direct influence on positive and negative affective reactions tied to the job search, influencing subsequent positive (i.e., metacognitive strategies) and negative (i.e., affective rumination) cognitive processes. Metacognitive strategies, in turn, impact both the number of résumés sent and hours spent job seeking each week. Moreover, lower feedback self‐efficacy amplifies the relationship between feedback quality and negative affective reactions. Our results highlight the importance of high‐quality feedback in helping job seekers effectively regulate week‐to‐week.