971 research outputs found

    Physicochemical implications of cyanobacteria oxidation with Fe(VI)

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    Increases in harmful algal blooms has negatively impacted many surface-sourced drinking water utilities. To control these blooms, many water utilities implement pre-oxidation with ozone, chlorine, or permanganate; however, pre-oxidation of algae has both positive and negative water quality outcomes. This study investigated ferrate (Fe(VI)) as an alternative oxidant by measuring its effect on cell lysing, surface characteristics, and coagulation in waters containing the cyanobacteria Microcystis aeruginosa. Bench scale studies were conducted to examine the complex combination of processes in a Fe(VI)-algae system. These processes were characterized by fluorescence index, surface charge, collision frequency modeling, particle counts and sphericity, total nitrogen, and ferrate decomposition measurements. Results showed that Fe(VI) lysed algal cells, but further oxidation of released organic matter is possible. The presence of algae did not significantly impact the rate of Fe(VI) decomposition. Fe(VI) pre-oxidation may also be capable of decreasing the formation of nitrogenated disinfection byproducts through subsequent oxidation of released nitrogen rich organic matter. Streaming current and zeta potential results indicate destabilization of the resulting algae and iron suspension was incomplete under most conditions. Particle collision frequency modeling indicates fluid shear to be an important aggregation mechanism of the resulting suspension. Overall, Fe(VI) is a viable alternative to other strong oxidants for water utilities struggling with harmful algal blooms, but the final fate of the resulting organic matter must be further studied

    The Simons Observatory Large Aperture Telescope Receiver

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    The Simons Observatory (SO) Large Aperture Telescope Receiver (LATR) will be coupled to the Large Aperture Telescope located at an elevation of 5,200 m on Cerro Toco in Chile. The resulting instrument will produce arcminute-resolution millimeter-wave maps of half the sky with unprecedented precision. The LATR is the largest cryogenic millimeter-wave camera built to date with a diameter of 2.4 m and a length of 2.6 m. It cools 1200 kg of material to 4 K and 200 kg to 100 mk, the operating temperature of the bolometric detectors with bands centered around 27, 39, 93, 145, 225, and 280 GHz. Ultimately, the LATR will accommodate 13 40 cm diameter optics tubes, each with three detector wafers and a total of 62,000 detectors. The LATR design must simultaneously maintain the optical alignment of the system, control stray light, provide cryogenic isolation, limit thermal gradients, and minimize the time to cool the system from room temperature to 100 mK. The interplay between these competing factors poses unique challenges. We discuss the trade studies involved with the design, the final optimization, the construction, and ultimate performance of the system

    The Atacama Cosmology Telescope: A Measurement of the DR6 CMB Lensing Power Spectrum and its Implications for Structure Growth

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    We present new measurements of cosmic microwave background (CMB) lensing over 94009400 sq. deg. of the sky. These lensing measurements are derived from the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) CMB dataset, which consists of five seasons of ACT CMB temperature and polarization observations. We determine the amplitude of the CMB lensing power spectrum at 2.3%2.3\% precision (43σ43\sigma significance) using a novel pipeline that minimizes sensitivity to foregrounds and to noise properties. To ensure our results are robust, we analyze an extensive set of null tests, consistency tests, and systematic error estimates and employ a blinded analysis framework. The baseline spectrum is well fit by a lensing amplitude of Alens=1.013±0.023A_{\mathrm{lens}}=1.013\pm0.023 relative to the Planck 2018 CMB power spectra best-fit Λ\LambdaCDM model and Alens=1.005±0.023A_{\mathrm{lens}}=1.005\pm0.023 relative to the ACT DR4+WMAP\text{ACT DR4} + \text{WMAP} best-fit model. From our lensing power spectrum measurement, we derive constraints on the parameter combination S8CMBLâ‰ĄÏƒ8(Ωm/0.3)0.25S^{\mathrm{CMBL}}_8 \equiv \sigma_8 \left({\Omega_m}/{0.3}\right)^{0.25} of S8CMBL=0.818±0.022S^{\mathrm{CMBL}}_8= 0.818\pm0.022 from ACT DR6 CMB lensing alone and S8CMBL=0.813±0.018S^{\mathrm{CMBL}}_8= 0.813\pm0.018 when combining ACT DR6 and Planck NPIPE CMB lensing power spectra. These results are in excellent agreement with Λ\LambdaCDM model constraints from Planck or ACT DR4+WMAP\text{ACT DR4} + \text{WMAP} CMB power spectrum measurements. Our lensing measurements from redshifts z∌0.5z\sim0.5--55 are thus fully consistent with Λ\LambdaCDM structure growth predictions based on CMB anisotropies probing primarily z∌1100z\sim1100. We find no evidence for a suppression of the amplitude of cosmic structure at low redshiftsComment: 45+21 pages, 50 figures. Prepared for submission to ApJ. Also see companion papers Madhavacheril et al and MacCrann et a

    The Atacama Cosmology Telescope: High-resolution component-separated maps across one-third of the sky

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    Observations of the millimeter sky contain valuable information on a number of signals, including the blackbody cosmic microwave background (CMB), Galactic emissions, and the Compton-yy distortion due to the thermal Sunyaev-Zel'dovich (tSZ) effect. Extracting new insight into cosmological and astrophysical questions often requires combining multi-wavelength observations to spectrally isolate one component. In this work, we present a new arcminute-resolution Compton-yy map, which traces out the line-of-sight-integrated electron pressure, as well as maps of the CMB in intensity and E-mode polarization, across a third of the sky (around 13,000 sq.~deg.). We produce these through a joint analysis of data from the Atacama Cosmology Telescope (ACT) Data Release 4 and 6 at frequencies of roughly 93, 148, and 225 GHz, together with data from the \textit{Planck} satellite at frequencies between 30 GHz and 545 GHz. We present detailed verification of an internal linear combination pipeline implemented in a needlet frame that allows us to efficiently suppress Galactic contamination and account for spatial variations in the ACT instrument noise. These maps provide a significant advance, in noise levels and resolution, over the existing \textit{Planck} component-separated maps and will enable a host of science goals including studies of cluster and galaxy astrophysics, inferences of the cosmic velocity field, primordial non-Gaussianity searches, and gravitational lensing reconstruction of the CMB.Comment: The Compton-y map and associated products will be made publicly available upon publication of the paper. The CMB T and E mode maps will be made available when the DR6 maps are made publi

    The Atacama Cosmology Telescope: DR6 Gravitational Lensing Map and Cosmological Parameters

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    We present cosmological constraints from a gravitational lensing mass map covering 9400 sq. deg. reconstructed from CMB measurements made by the Atacama Cosmology Telescope (ACT) from 2017 to 2021. In combination with BAO measurements (from SDSS and 6dF), we obtain the amplitude of matter fluctuations σ8=0.819±0.015\sigma_8 = 0.819 \pm 0.015 at 1.8% precision, S8â‰ĄÏƒ8(Ωm/0.3)0.5=0.840±0.028S_8\equiv\sigma_8({\Omega_{\rm m}}/0.3)^{0.5}=0.840\pm0.028 and the Hubble constant H0=(68.3±1.1) km s−1 Mpc−1H_0= (68.3 \pm 1.1)\, \text{km}\,\text{s}^{-1}\,\text{Mpc}^{-1} at 1.6% precision. A joint constraint with CMB lensing measured by the Planck satellite yields even more precise values: σ8=0.812±0.013\sigma_8 = 0.812 \pm 0.013, S8â‰ĄÏƒ8(Ωm/0.3)0.5=0.831±0.023S_8\equiv\sigma_8({\Omega_{\rm m}}/0.3)^{0.5}=0.831\pm0.023 and H0=(68.1±1.0) km s−1 Mpc−1H_0= (68.1 \pm 1.0)\, \text{km}\,\text{s}^{-1}\,\text{Mpc}^{-1}. These measurements agree well with Λ\LambdaCDM-model extrapolations from the CMB anisotropies measured by Planck. To compare these constraints to those from the KiDS, DES, and HSC galaxy surveys, we revisit those data sets with a uniform set of assumptions, and find S8S_8 from all three surveys are lower than that from ACT+Planck lensing by varying levels ranging from 1.7-2.1σ\sigma. These results motivate further measurements and comparison, not just between the CMB anisotropies and galaxy lensing, but also between CMB lensing probing z∌0.5−5z\sim 0.5-5 on mostly-linear scales and galaxy lensing at z∌0.5z\sim 0.5 on smaller scales. We combine our CMB lensing measurements with CMB anisotropies to constrain extensions of Λ\LambdaCDM, limiting the sum of the neutrino masses to ∑mÎœ<0.12\sum m_{\nu} < 0.12 eV (95% c.l.), for example. Our results provide independent confirmation that the universe is spatially flat, conforms with general relativity, and is described remarkably well by the Λ\LambdaCDM model, while paving a promising path for neutrino physics with gravitational lensing from upcoming ground-based CMB surveys.Comment: 30 pages, 16 figures, prepared for submission to ApJ. Cosmological likelihood data is here: https://lambda.gsfc.nasa.gov/product/act/actadv_prod_table.html ; likelihood software is here: https://github.com/ACTCollaboration/act_dr6_lenslike . Also see companion papers Qu et al and MacCrann et al. Mass maps will be released when papers are publishe

    Machine learning uncovers the most robust self-report predictors of relationship quality across 43 longitudinal couples studies

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    Given the powerful implications of relationship quality for health and well-being, a central mission of relationship science is explaining why some romantic relationships thrive more than others. This large-scale project used machine learning (i.e., Random Forests) to 1) quantify the extent to which relationship quality is predictable and 2) identify which constructs reliably predict relationship quality. Across 43 dyadic longitudinal datasets from 29 laboratories, the top relationship-specific predictors of relationship quality were perceived-partner commitment, appreciation, sexual satisfaction, perceived-partner satisfaction, and conflict. The top individual-difference predictors were life satisfaction, negative affect, depression, attachment avoidance, and attachment anxiety. Overall, relationship-specific variables predicted up to 45% of variance at baseline, and up to 18% of variance at the end of each study. Individual differences also performed well (21% and 12%, respectively). Actor-reported variables (i.e., own relationship-specific and individual-difference variables) predicted two to four times more variance than partner-reported variables (i.e., the partner’s ratings on those variables). Importantly, individual differences and partner reports had no predictive effects beyond actor-reported relationship-specific variables alone. These findings imply that the sum of all individual differences and partner experiences exert their influence on relationship quality via a person’s own relationship-specific experiences, and effects due to moderation by individual differences and moderation by partner-reports may be quite small. Finally, relationship-quality change (i.e., increases or decreases in relationship quality over the course of a study) was largely unpredictable from any combination of self-report variables. This collective effort should guide future models of relationships

    Examining the Latent Structure and Correlates of Sensory Reactivity in Autism: A Multi-Site Integrative Data Analysis by the Autism Sensory Research Consortium

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    BACKGROUND: Differences in responding to sensory stimuli, including sensory hyperreactivity (HYPER), hyporeactivity (HYPO), and sensory seeking (SEEK) have been observed in autistic individuals across sensory modalities, but few studies have examined the structure of these supra-modal traits in the autistic population. METHODS: Leveraging a combined sample of 3868 autistic youth drawn from 12 distinct data sources (ages 3-18 years and representing the full range of cognitive ability), the current study used modern psychometric and meta-analytic techniques to interrogate the latent structure and correlates of caregiver-reported HYPER, HYPO, and SEEK within and across sensory modalities. Bifactor statistical indices were used to both evaluate the strength of a general response pattern factor for each supra-modal construct and determine the added value of modality-specific response pattern scores (e.g., Visual HYPER). Bayesian random-effects integrative data analysis models were used to examine the clinical and demographic correlates of all interpretable HYPER, HYPO, and SEEK (sub)constructs. RESULTS: All modality-specific HYPER subconstructs could be reliably and validly measured, whereas certain modality-specific HYPO and SEEK subconstructs were psychometrically inadequate when measured using existing items. Bifactor analyses supported the validity of a supra-modal HYPER construct (ω LIMITATIONS: Conclusions may not be generalizable beyond the specific pool of items used in the current study, which was limited to caregiver report of observable behaviors and excluded multisensory items that reflect many real-world sensory experiences. CONCLUSION: Of the three sensory response patterns, only HYPER demonstrated sufficient evidence for valid interpretation at the supra-modal level, whereas supra-modal HYPO/SEEK constructs demonstrated substantial psychometric limitations. For clinicians and researchers seeking to characterize sensory reactivity in autism, modality-specific response pattern scores may represent viable alternatives that overcome many of these limitations

    Robust estimation of bacterial cell count from optical density

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    Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

    Observation of tW production in the single-lepton channel in pp collisions at root s=13 TeV

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    A measurement of the cross section of the associated production of a single top quark and a W boson in final states with a muon or electron and jets in proton-proton collisions at root s = 13 TeV is presented. The data correspond to an integrated luminosity of 36 fb(-1) collected with the CMS detector at the CERN LHC in 2016. A boosted decision tree is used to separate the tW signal from the dominant t (t) over bar background, whilst the subleading W+jets and multijet backgrounds are constrained using data-based estimates. This result is the first observation of the tW process in final states containing a muon or electron and jets, with a significance exceeding 5 standard deviations. The cross section is determined to be 89 +/- 4 (stat) +/- 12 (syst) pb, consistent with the standard model.Peer reviewe
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