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These collections include publications and data from University of Arizona faculty, staff and researchers. The UA Faculty Publications collection consists primarily of open access versions of published journal articles, but also contains conference proceedings and other unique materials from faculty, staff and researchers. Organizational collections, such as the College of Agricultural and Life Sciences Publications, and Water Resources Research Center, contain additional faculty publications such as departmentally produced technical bulletins, technical reports, and working papers.
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UCHL1, a deubiquitinating enzyme, regulates lung endothelial cell permeability in vitro and in vivoIncreasing evidence suggests an important role for deubiquitinating enzymes (DUBs) in modulating a variety of biological functions and diseases. We previously identified the upregulation of the DUB ubiquitin carboxyl terminal hydrolase 1 (UCHL1) in murine ventilator-induced lung injury (VILI). However, the role of UCHL1 in modulating vascular permeability, a cardinal feature of acute lung injury (ALI) in general, remains unclear. We investigated the role of UCHL1 in pulmonary endothelial cell (EC) barrier function in vitro and in vivo and examined the effects of UCHL1 on VE-cadherin and claudin-5 regulation, important adherens and tight junctional components, respectively. Measurements of transendothelial electrical resistance confirmed decreased barrier enhancement induced by hepatocyte growth factor (HGF) and increased thrombin-induced permeability in both UCHL1-silenced ECs and in ECs pretreated with LDN-57444 (LDN), a pharmacological UCHL1 inhibitor. In addition, UCHL1 knockdown (siRNA) was associated with decreased expression of VE-cadherin and claudin-5, whereas silencing of the transcription factor FoxO1 restored claudin-5 levels. Finally, UCHL1 inhibition in vivo via LDN was associated with increased VILI in a murine model. These findings support a prominent functional role of UCHL1 in regulating lung vascular permeability via alterations in adherens and tight junctions and implicate UCHL1 as an important mediator of ALI.
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Social support and healthcare utilization of caregivers of Latinas with breast cancerBackground: Family caregivers experience significant health consequences related to caregiving, including higher mortality rates. Latino caregivers may have additional challenges related to social determinants of health. Gender and social support are key factors to consider in the context of chronic illnesses and healthcare use in caregivers of Latinos diagnosed with cancer. Purpose: The purpose of this study was to examine the moderating effect of gender and social support on the relationship between chronic illnesses and healthcare utilization in caregivers of Latina breast cancer survivors. Methods: This was a secondary analysis of family caregivers from an experimental study with breast cancer survivors and their designated family caregivers. Participants completed telephone surveys about demographics, presence of chronic illnesses, frequency of emergency department, urgent care, and hospital visits, social support, and acculturation. Data were analyzed for direct and moderated relationships. Results: There was a significant relationship between number of chronic illnesses and healthcare utilization, informational support, and social isolation. Income and acculturation were not related to chronic illnesses or healthcare utilization. Gender did not moderate the relationship between chronic illnesses and healthcare utilization. Informational support was a marginal moderator of the relationship between chronic illnesses and healthcare utilization alone and with acculturation and income included as covariates. Conclusions: Clinicians should consider the influence of informational support and social isolation on chronic illnesses and healthcare use in caregivers of Latina breast cancer survivors, specifically, how these factors may influence navigation of the healthcare system. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.
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MAVS regulates the quality of the antibody response to West-Nile VirusA key difference that distinguishes viral infections from protein immunizations is the recognition of viral nucleic acids by cytosolic pattern recognition receptors (PRRs). Insights into the functions of cytosolic PRRs such as the RNA-sensing Rig-I-like receptors (RLRs) in the instruction of adaptive immunity are therefore critical to understand protective immunity to infections. West Nile virus (WNV) infection of mice deficent of RLR-signaling adaptor MAVS results in a defective adaptive immune response. While this finding suggests a role for RLRs in the instruction of adaptive immunity to WNV, it is difficult to interpret due to the high WNV viremia, associated exessive antigen loads, and pathology in the absence of a MAVS-dependent innate immune response. To overcome these limitations, we have infected MAVS-deficient (MAVS(KO)) mice with a single-round-of-infection mutant of West Nile virus. We show that MAVS(KO) mice failed to produce an effective neutralizing antibody response to WNV despite normal antibody titers against the viral WNV-E protein. This defect occurred independently of antigen loads or overt pathology. The specificity of the antibody response in infected MAVS(KO) mice remained unchanged and was still dominated by antibodies that bound the neutralizing lateral ridge (LR) epitope in the DIII domain of WNV-E. Instead, MAVS(KO) mice produced IgM antibodies, the dominant isotype controlling primary WNV infection, with lower affinity for the DIII domain. Our findings suggest that RLR-dependent signals are important for the quality of the humoral immune response to WNV. Author summary A key difference that distinguishes viral infection from protein immunization is the detection of viral nucleic acids by cytosolic pattern recognition receptors (PRRs) including the RNA-sensing Rig-I-like receptors (RLRs). Insights into the specific function of RLRs are therefore critical for the understanding of protective immunity to infections. Here, we have infected mice deficient in RLR signaling with an attenuated mutant of West Nile virus (WNV). We show that the anti-viral antibody response of these mice failed to neutralize the virus effectively because the majority of WNV-specific antibodies poorly bound the virus. Our findings suggest that the detection of WNV by RLRs regulates the quality of the anti-viral antibody response.
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Accommodating individual travel history and unsampled diversity in Bayesian phylogeographic inference of SARS-CoV-2Spatiotemporal bias in genome sampling can severely confound discrete trait phylogeographic inference. This has impeded our ability to accurately track the spread of SARS-CoV-2, the virus responsible for the COVID-19 pandemic, despite the availability of unprecedented numbers of SARS-CoV-2 genomes. Here, we present an approach to integrate individual travel history data in Bayesian phylogeographic inference and apply it to the early spread of SARS-CoV-2. We demonstrate that including travel history data yields i) more realistic hypotheses of virus spread and ii) higher posterior predictive accuracy compared to including only sampling location. We further explore methods to ameliorate the impact of sampling bias by augmenting the phylogeographic analysis with lineages from undersampled locations. Our reconstructions reinforce specific transmission hypotheses suggested by the inclusion of travel history data, but also suggest alternative routes of virus migration that are plausible within the epidemiological context but are not apparent with current sampling efforts. Spatiotemporal sampling gaps in existing pathogen genomic data limits their use in understanding epidemiological patterns. Here, the authors apply a phylogeographic approach with SARS-CoV-2 genomes to accurately reproduce pathogen spread by accounting for spatial biases and travel history of the individual.
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Structural equation modeling to detect correlates of childhood vaccination: A moderated mediation analysisObjectives This study used a health belief theory derived framework and structural equation model to examine moderators, mediators, and direct and indirect predictors of childhood vaccination. Methods A secondary analysis was conducted using data collected from a cross-sectional survey of a random sample of 1599 parents living in urban and rural areas of Mysore district, India. Applying two-stage probability proportionate-to-size sampling, adolescent girls attending 7th through 10th grades in 23 schools were selected to take home a questionnaire to be answered by their parents to primarily assess HPV vaccine intentions. Parents were also asked whether their children had received one dose of Bacillus Calmette-Guerin; three doses of Diphtheria, Pertussis, Tetanus; three doses of oral Polio vaccine; and one dose of Measles vaccine. In addition, parents were asked about their attitudes towards childhood vaccination. Results Out of the 1599 parents, 52.2% reported that their children had received all the routine vaccines (fully vaccinated); 42.7% reported their children had missed at least one routine vaccine, and 5.2% reported that their children had missed all routine vaccinations. Perceptions about the benefits/facilitators to childhood vaccination significantly predicted the full vaccination rate (standardized regression coefficient (beta) = 0.29) directly and mediated the effect of parental education (beta = 0.11) and employment (beta = -0.06) on the rate of full vaccination. Parental education was significantly associated indirectly with higher rates of full vaccination (beta = 0.11). Parental employment was significantly associated indirectly with decreasing rates of full vaccination (beta = -0.05). Area of residence moderated the role of religion (beta = 0.24) and the `number of children' in a family (beta = 0.33) on parental perceptions about barriers to childhood vaccination. The model to data fit was acceptable (Root Mean Square Error of Approximation = 0.02, 95% CI 0.018 to 0.023; Comparative Fit Index = 0.92; Tucker-Lewis Index = 0.91). Conclusions Full vaccination rate was relatively low among children in Mysore, especially among parents who were unsure about the benefits of routine vaccination and those with low educational levels. Interventions increasing awareness of the benefits of childhood vaccination that target rural parents with lower levels of education may help increase the rate of full childhood vaccination in India.
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Sampling density and date along with species selection influence spatial representation of tree-ring reconstructionsOur understanding of the natural variability of hydroclimate before the instrumental period (ca. 1900 CE in the United States) is largely dependent on tree-ring-based reconstructions. Large-scale soil moisture reconstructions from a network of tree-ring chronologies have greatly improved our understanding of the spatial and temporal variability in hydroclimate conditions, particularly extremes of both drought and pluvial (wet) events. However, certain regions within these large-scale network reconstructions in the US are modeled by few tree-ring chronologies. Further, many of the chronologies currently publicly available on the International Tree-Ring Data Bank (ITRDB) were collected in the 1980s and 1990s, and thus our understanding of the sensitivity of radial growth to soil moisture in the US is based on a period that experienced multiple extremely severe droughts and neglects the impacts of recent, rapid global change. In this study, we expanded the tree-ring network of the Ohio River valley in the US, a region with sparse coverage. We used a total of 72 chronologies across 15 species to examine how increasing the density of the tree-ring network influences the representation of reconstructing the Palmer Meteorological Drought Index (PMDI). Further, we tested how the sampling date and therefore the calibration period influenced the reconstruction models by creating reconstructions that ended in the year 1980 and compared them to reconstructions ending in 2010 from the same chronologies. We found that in- creasing the density of the tree-ring network resulted in reconstructed values that better matched the spatial variability of instrumentally recorded droughts and, to a lesser extent, pluvials. By extending the calibration period to 2010 compared to 1980, the sensitivity of tree rings to PMDI decreased in the southern portion of our region where severe drought conditions have been absent over recent decades. We emphasize the need of building a high-density tree-ring network to better represent the spatial variability of past droughts and pluvials. Further, chronologies on the ITRDB need updating regularly to better understand how the sensitivity of tree rings to climate may vary through time.
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Partnering With Massage Therapists to Communicate Information on Reducing the Risk of Skin Cancer Among Clients: Longitudinal StudyBackground: Skin cancer affects millions of Americans and is an important focus of disease prevention efforts. Partnering with non-health care practitioners such as massage therapists (MTs) can reduce the risk of skin cancer. MTs see clients' skin on a regular basis, which can allow MTs to initiate "helping conversations" (ie, brief behavioral interventions aimed at reducing the risk of skin cancer). Objective: The purpose of this study was to evaluate (1) the feasibility of recruiting, enrolling, and retaining Arizona MTs in an online electronic training (e-training) and (2) the preliminary efficacy of e-training on knowledge, attitudes/beliefs, and practice of risk reduction for skin cancer. We explored MTs' ability to assess suspicious skin lesions. Methods: We adapted the existing educational content on skin cancer for applicability to MTs and strategies from previous research on helping conversations. We assessed the feasibility of providing such e-training, using Research Electronic Data Capture (REDCap) tools for data capture. We assessed the preliminary efficacy using established self-report surveys at baseline, immediately post training, and at 3 and 6 months post training. Results: A total of 95 participants enrolled in the study, of which 77% (73/95) completed the assessments at 6 months (overall attrition=23%). Project satisfaction and e-training acceptability were high. Knowledge, personal behaviors (skin self-examination, clinical skin examination, sun protection frequency), and practice attitudes (appropriateness and comfort with client-focused communication) of risk reduction for skin cancer improved significantly and were sustained throughout the study. Conclusions: The e-training was feasible and could be delivered online successfully to MTs. Participants were highly satisfied with and accepting of the e-training. As such, e-training has potential as an intervention in larger trials with MTs for reducing the risk of skin cancer.
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Global mean surface temperature and climate sensitivity of the early Eocene Climatic Optimum (EECO), Paleocene–Eocene Thermal Maximum (PETM), and latest PaleoceneAccurate estimates of past global mean surface temperature (GMST) help to contextualise future climate change and are required to estimate the sensitivity of the climate system to CO2 forcing through Earth's history. Previous GMST estimates for the latest Paleocene and early Eocene (similar to 57 to 48 million years ago) span a wide range (similar to 9 to 23 degrees C higher than pre-industrial) and prevent an accurate assessment of climate sensitivity during this extreme greenhouse climate interval. Using the most recent data compilations, we employ a multi-method experimen- tal framework to calculate GMST during the three DeepMIP target intervals: (1) the latest Paleocene (similar to 57 Ma), (2) the Paleocene-Eocene Thermal Maximum (PETM; 56 Ma), and (3) the early Eocene Climatic Optimum (EECO; 53.3 to 49.1 Ma). Using six different methodologies, we find that the average GMST estimate (66% confidence) during the latest Paleocene, PETM, and EECO was 26.3 degrees C (22.3 to 28.3 degrees C), 31.6 degrees C (27.2 to 34.5 degrees C), and 27.0 degrees C (23.2 to 29.7 degrees C), respectively. GMST estimates from the EECO are similar to 10 to 16 degrees C warmer than pre-industrial, higher than the estimate given by the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (9 to 14 degrees C higher than pre-industrial). Leveraging the large "signal" associated with these extreme warm climates, we combine estimates of GMST and CO2 from the latest Paleocene, PETM, and EECO to calculate gross estimates of the average climate sensitivity between the early Paleogene and today. We demonstrate that "bulk" equilibrium climate sensitivity (ECS; 66% confidence) during the latest Paleocene, PETM, and EECO is 4.5 degrees C (2.4 to 6.8 degrees C), 3.6 degrees C (2.3 to 4.7 degrees C), and 3.1 degrees C (1.8 to 4.4 degrees C) per doubling of CO2. These values are generally similar to those assessed by the IPCC (1.5 to 4.5 ffiC per doubling CO2) but appear incompatible with low ECS values (< 1 :5 per doubling CO2).
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Contributions of cis- and trans-Regulatory Evolution to Transcriptomic Divergence across Populations in the Drosophila mojavensis Larval BrainNatural selection on gene expression was originally predicted to result primarily in cis- rather than trans-regulatory evolution, due to the expectation of reduced pleiotropy. Despite this, numerous studies have ascribed recent evolutionary divergence in gene expression predominantly to trans-regulation. Performing RNA-seq on single isofemale lines from genetically distinct populations of the cactophilic fly Drosophila mojavensis and their F-1 hybrids, we recapitulated this pattern in both larval brains and whole bodies. However, we demonstrate that improving the measurement of brain expression divergence between populations by using seven additional genotypes considerably reduces the estimate of trans-regulatory contributions to expression evolution. We argue that the finding of trans-regulatory predominance can result from biases due to environmental variation in expression or other sources of noise, and that cis-regulation is likely a greater contributor to transcriptional evolution across D. mojavensis populations. Lastly, we merge these lines of data to identify several previously hypothesized and intriguing novel candidate genes, and suggest that the integration of regulatory and population-level transcriptomic data can provide useful filters for the identification of potentially adaptive genes.
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Only a Single Taxonomically Restricted Gene Family in the Drosophila melanogaster Subgroup Can Be Identified with High ConfidenceTaxonomically restricted genes (TRGs) are genes that are present only in one clade. Protein-coding TRGs may evolve de novo from previously noncoding sequences: functional ncRNA, introns, or alternative reading frames of older protein-coding genes, or intergenic sequences. A major challenge in studying de novo genes is the need to avoid both false-positives (nonfunctional open reading frames and/or functional genes that did not arise de novo) and false-negatives. Here, we search conservatively for high-confidence TRGs as the most promising candidates for experimental studies, ensuring functionality through conservation across at least two species, and ensuring de novo status through examination of homologous noncoding sequences. Our pipeline also avoids ascertainment biases associated with preconceptions of how de novo genes are born. We identify one TRG family that evolved de novo in the Drosophila melanogaster subgroup. This TRG family contains single-copy genes in Drosophila simulans and Drosophila sechellia. It originated in an intron of a well-established gene, sharing that intron with another well-established gene upstream. These TRGs contain an intron that predates their open reading frame. These genes have not been previously reported as de novo originated, and to our knowledge, they are the best Drosophila candidates identified so far for experimental studies aimed at elucidating the properties of de novo genes.
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Environmental impact analysis of high-rise buildings for resilient urban developmentIn recent years, the construction of high-rise buildings as an urban development strategy has been accepted in many megacities. High-rise buildings have positive as well as negative impacts on urban environments. Therefore, the environmental impact assessment of high-rise buildings for establishing strategies to ensure sustainable and resilient urban development is essential. In this study, the environmental impact of high-rise buildings with a resilient development mindset was assessed. Resilience mindset provides an approach for including the uncertainties and interdependence of systems and processes for planning new sustainable developments and assessment methods. The corresponding environmental impact assessment was performed by monitoring the structural changes and their impacts on the function of ecosystem and environmental services. Here, the positive and negative impacts of high-rise buildings were evaluated. Protection of impervious surfaces as a positive impact and changing the natural pattern of urban wind flow as a negative impact were considered. The transparency of the results and the reduction of uncertainty are the advantages of using the resilience mindset in the environmental impact assessment. The results of this study suggest that the resilient development mindset can improve the environmental assessment through the adoption of appropriate indicators on multiple scales and differentiating between the primary and secondary effects. (C) 2020 Sharif University of Technology. All rights reserved.
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The impact of spectroscopic incompleteness in direct calibration of redshift distributions for weak lensing surveysObtaining accurate distributions of galaxy redshifts is a critical aspect of weak lensing cosmology experiments. One of the methods used to estimate and validate redshift distributions is to apply weights to a spectroscopic sample, so that their weighted photometry distribution matches the target sample. In this work, we estimate the selection bias in redshift that is introduced in this procedure. We do so by simulating the process of assembling a spectroscopic sample (including observer-assigned confidence flags) and highlight the impacts of spectroscopic target selection and redshift failures. We use the first year (Y1) weak lensing analysis in Dark Energy Survey (DES) as an example data set but the implications generalize to all similar weak lensing surveys. We find that using colour cuts that are not available to the weak lensing galaxies can introduce biases of up to Delta z similar to 0.04 in the weighted mean redshift of different redshift intervals (Delta z similar to 0.015 in the case most relevant to DES). To assess the impact of incompleteness in spectroscopic samples, we select only objects with high observer-defined confidence flags and compare the weighted mean redshift with the true mean. We find that the mean redshift of the DES Y1 weak lensing sample is typically biased at the Delta z = 0.005-0.05 level after the weighting is applied. The bias we uncover can have either sign, depending on the samples and redshift interval considered. For the highest redshift bin, the bias is larger than the uncertainties in the other DES Y1 redshift calibration methods, justifying the decision of not using this method for the redshift estimations. We discuss several methods to mitigate this bias.
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Activity-Dependent Global Downscaling of Evoked Neurotransmitter Release across Glutamatergic Inputs in DrosophilaWithin mammalian brain circuits, activity-dependent synaptic adaptations, such as synaptic scaling, stabilize neuronal activity in the face of perturbations. Stability afforded through synaptic scaling involves uniform scaling of quantal amplitudes across all synaptic inputs formed on neurons, as well as on the postsynaptic side. It remains unclear whether activity-dependent uniform scaling also operates within peripheral circuits. We tested for such scaling in a Drosophila larval neuromuscular circuit, where the muscle receives synaptic inputs from different motoneurons. We used motoneuron-specific genetic manipulations to increase the activity of only one motoneuron and recordings of postsynaptic currents from inputs formed by the different motoneurons. We discovered an adaptation which caused uniform downscaling of evoked neurotransmitter release across all inputs through decreases in release probabilities. This "presynaptic downscaling" maintained the relative differences in neurotransmitter release across all inputs around a homeostatic set point, caused a compensatory decrease in synaptic drive to the muscle affording robust and stable muscle activity, and was induced within hours. Presynaptic downscaling was associated with an activity-dependent increase in Drosophila vesicular glutamate transporter expression. Activity-dependent uniform scaling can therefore manifest also on the presynaptic side to produce robust and stable circuit outputs. Within brain circuits, uniform downscaling on the postsynaptic side is implicated in sleep- and memory-related processes. Our results suggest that evaluation of such processes might be broadened to include uniform downscaling on the presynaptic side.SIGNIFICANCE STATEMENT To date, compensatory adaptations which stabilise target cell activity through activity-dependent global scaling have been observed only within central circuits, and on the postsynaptic side. Considering that maintenance of stable activity is imperative for the robust function of the nervous system as a whole, we tested whether activity-dependent global scaling could also manifest within peripheral circuits. We uncovered a compensatory adaptation which causes global scaling within a peripheral circuit and on the presynaptic side through uniform downscaling of evoked neurotransmitter release. Unlike in central circuits, uniform scaling maintains functionality over a wide, rather than a narrow, operational range, affording robust and stable activity. Activity-dependent global scaling therefore operates on both the presynaptic and postsynaptic sides to maintain target cell activity.
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An Aridity Index‐Based Formulation of Streamflow ComponentsDirect runoff and baseflow are the two primary components of total streamflow, and their accurate estimation is indispensable for a variety of hydrologic applications. While direct runoff is the quick response stemming from surface and shallow subsurface flow paths and is often associated with floods, baseflow represents the groundwater contribution from stored sources (e.g., groundwater) to streams and is crucial for environmental flow regulations, and water supply, among others. L'vovich (1979, ) proposed a two-step water balance partitioning, where precipitation is divided into direct runoff and catchment wetting, followed by the disaggregation of the latter into baseflow and evapotranspiration. Here, we investigate the role of the aridity index (ratio between mean-annual potential evapotranspiration and precipitation) in controlling the long-term (mean-annual) fluxes of direct runoff and baseflow. We present an analytical solution beginning with similar assumptions as proposed by Budyko (1974, ), leading to two complementary expressions for the two fluxes. The aridity index explained 77% and 89% of variability in direct runoff and baseflow from 378 catchments within the continental United States, while our formulations were able to reproduce the patterns of water balance partitioning proposed by L'vovich (1979, ) at the mean-annual timescale. Our approach can be used to further understand how climate and landscape controls the terrestrial water balance at mean-annual timescales, while also representing a step toward the prediction of baseflow and direct runoff at ungauged basins.
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Impact of secondary donor units on the excited-state properties and thermally activated delayed fluorescence (TADF) efficiency of pentacarbazole-benzonitrile emittersThe performance of organic light-emitting diodes based on thermally activated delayed fluorescence emitters depends on the efficiency of reverse intersystem crossing (RISC) processes, which are promoted by a small energy gap between the lowest singlet (S1) and triplet (T1) excited states and large spin-orbit couplings. Recently, it was proposed that the introduction of secondary donor units into 2,3,4,5,6-penta(9H-carbazol-9-yl)benzonitrile (5CzBN) can significantly increase the mixing between triplet states with charge-transfer (CT) and local-excitation characteristics and consequently increase the spin-orbit couplings. Here, the results of long-range corrected density functional theory calculations show that the main impact on the RISC rates of substituting 5CzBN with secondary donors is due to a decrease in adiabatic singlet-triplet energy gaps and intramolecular reorganization energies rather than to a change in spin-orbit couplings. Our calculations underline that at least two singlet and three triplet excited states contribute to the ISC/RISC processes in 5CzBN and its derivatives. In addition, we find that in all emitters, the lowest singlet excited-state potential energy surface has a double-minimum shape.
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A Quantitative Model‐Based Assessment of Stony Desert Landscape Evolution in the Hami Basin, China: Implications for Plio‐Pleistocene Dust Production in Eastern AsiaDust plays an important role in climate, and while our current representation of dust production includes shifts in vegetation, soil moisture, and ice cover, it does not account for the role of landscape evolution. Here, we use the Weather Research and Forecasting model coupled to an aerosol chemistry model to quantify the effects of arid landscape evolution on boundary layer conditions, dust production, and radiative properties in the Hami Basin, China, a dynamic stony desert in eastern Asia. Relative to today, altered surface roughness, sediment erodibility, and albedo combine to produce up to a similar to 44% increase in wind speeds (mean approximate to 15%), up to a similar to 59% increase in dust loading (mean approximate to 30%), and up to a similar to 4.4 W m(-2) increase in downwelling radiation (mean approximate to 2.4 W m(-2)) over the Hami Basin. Our modeling results, along with geomorphological data for the western Gobi Desert, provide evidence that stony deserts acted as important Plio-Pleistocene dust sources. Plain Language Summary Dust from the breakdown of rocks and minerals plays an important role in Earth's atmosphere by absorbing or scattering incoming solar radiation, and by seeding clouds. Once deposited, iron-rich dust can fertilize surface ocean waters and terrestrial soils for the growth of organisms, making dust important in the global carbon cycle. Because of its role in modifying Earth's climate, we must accurately understand ancient dust production. To test the hypothesis that past changes in dust production impacted climate, we altered the surface properties of the western Gobi Desert, a location that had a very different landscape thousands to millions of years ago, and simulated changes in wind and dust using a regional climate model. We found that this area would have experienced increased wind speeds by up to similar to 40%, increased dust loading by up to similar to 60%, and substantially altered incoming solar radiation in response to land surface evolution.
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Assessing cosmic acceleration with the Alcock–Paczyński effect in the SDSS-IV quasar catalogueThe geometry of the Universe may be probed using the Alcock-Paczynski (AP) effect, in which the observed redshift size of a spherical distribution of sources relative to its angular size varies according to the assumed cosmological model. Past applications of this effect have been limited, however, by a paucity of suitable sources and mitigating astrophysical factors, such as internal redshift-space distortions and poorly known source evolution. In this Letter, we introduce a new test based on the AP effect that avoids the use of spatially bound systems, relying instead on sub-samples of quasars at redshifts z less than or similar to 1.5 in the Sloan Digital Sky Survey IV, with a possible extension to higher redshifts and improved precision when this catalogue is expanded by upcoming surveys. We here use this method to probe the redshift-dependent expansion rate in three pertinent Friedmann-Lemaitre-Robertson-Walker cosmologies: Lambda cold dark matter (Lambda CDM), which predicts a transition from deceleration to acceleration at z similar to 0.7; Einstein-de Sitter, in which the Universe is always decelerating; and the R-h = ct universe, which expands at a constant rate. Lambda CDM is consistent with these data, but R-h = ct is favoured overall.
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Solar Wind Electron Parameters Determination on Wind Spacecraft Using Quasi‐Thermal Noise SpectroscopyQuasi-thermal noise (QTN) spectroscopy has been extensively used as an accurate tool to measure electron density and temperature in space plasmas. If the antenna length to radius ratio is sufficiently large, a typical measured spectrum clearly shows a resonance at the electron plasma frequency and a lower frequency plateau that quantify the electron distributions. The Wind spacecraft, with its long, thin antennas, is considered the mission par excellence for the implementation of the QTN method. However, a major issue in applying QTN spectroscopy is contamination from signals other than the ubiquitous plasma noise in the vicinity of plasma frequency, affecting the measured spectra and confusing their physical interpretation. In this work, we present a new method for selecting the observations of uncontaminated QTN, distinguishing it from other plasma and spacecraft effects. The selected measurements are used to obtain accurate values for both thermal and suprathermal electron parameters. Testing of the method on 1.5M observations under various conditions in the solar wind, including slow and fast wind and solar transients, confirms the reliability and accuracy of the method with no systematic flaws.
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Ion diffusion coefficients in poly(3-alkylthiophenes) for energy conversion and biosensing: role of side-chain length and microstructureConductive polymers are promising materials as active elements for energy storage and conversion devices due to mixed ion-electron conduction. The ion diffusion coefficient is a relative measure of the efficacy of ion transport, allowing for comparison between materials and electrochemical conditions. In this work, diffusion coefficients of hexafluorophosphate (PF6-) counterions in poly(3-alkylthiophene) (P3AT) materials are measured as a function of both side-chain length and microstructure using electrochemical impedance spectroscopy (EIS). For semi-crystalline films, the diffusion coefficient is found to be anomalous and nearly independent of applied electrochemical potential. The anomalous behavior of diffusion indicates that spin casting yields compact films with an enthalpic barrier to ion transport, attributed to ionic trapping. Diffusion coefficient values similar to 10(-11)cm(2)s(-1)were measured for all films, indicating interchain spacing, in the absence of strong intermolecular interactions with the electrolyte, is not a viable design strategy to control ion transport. For the prototypical system of poly(3-hexylthiophene), we observe almost no potential dependence in ion transport for regioregular and regiorandom films of comparable molecular weight, with both exhibiting anomalous diffusion. Alternatively, changing the microstructure of poly(3-hexylthiophene) to a mostly amorphous, ion-imprinted structure yields similar to 500x increase in the diffusion coefficient to similar to 2 x 10(-8)cm(2)s(-1)at 0.8 Vvs.Ag/Ag(+)with behavior closer to ordinary diffusion. Collectively, these results indicate new insight into ion transport in conductive polymers, where ionic trapping effects can be mitigated through electrodeposition protocols over post-synthesis processing (i.e.spin coating).
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Quantum-Enhanced Fiber-Optic Gyroscopes Using Quadrature Squeezing and Continuous-Variable EntanglementWe evaluate the fundamental performance of a fiber-optic gyroscope (FOG) design that is enhanced by the injection of a quantum-optical squeezed vacuum. In the presence of fiber loss, we compute the optimum attainable enhancement below the standard quantum limit in terms of the angular velocity estimator variance from a homodyne measurement. We find that currently realizable amounts of single-mode squeezing are sufficient to access the maximum quantitative improvement, but that this gain in maximum rotation sensitivity is limited to a marginal constant factor. We then propose an entanglement-enhanced FOG design that segments a fixed amount of available fiber into multiple fiber interferometers and feeds this sensor array with a multimode-entangled squeezed vacuum resource. Our design raises the fundamental improvement in sensitivity to an appreciable factor of e approximate to 2.718.
