971 research outputs found
Physicochemical implications of cyanobacteria oxidation with Fe(VI)
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
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
We present new measurements of cosmic microwave background (CMB) lensing over
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
precision ( 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
relative to the Planck 2018 CMB power spectra
best-fit CDM model and relative to
the best-fit model. From our lensing power
spectrum measurement, we derive constraints on the parameter combination
of
from ACT DR6 CMB lensing alone and
when combining ACT DR6 and Planck NPIPE
CMB lensing power spectra. These results are in excellent agreement with
CDM model constraints from Planck or
CMB power spectrum measurements. Our lensing measurements from redshifts
-- are thus fully consistent with CDM structure growth
predictions based on CMB anisotropies probing primarily . 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
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- 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- 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
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 at 1.8% precision,
and the Hubble
constant at
1.6% precision. A joint constraint with CMB lensing measured by the Planck
satellite yields even more precise values: ,
and . These measurements agree
well with CDM-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 from all three surveys are lower than that from ACT+Planck
lensing by varying levels ranging from 1.7-2.1. These results motivate
further measurements and comparison, not just between the CMB anisotropies and
galaxy lensing, but also between CMB lensing probing on
mostly-linear scales and galaxy lensing at on smaller scales. We
combine our CMB lensing measurements with CMB anisotropies to constrain
extensions of CDM, limiting the sum of the neutrino masses to 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 CDM 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
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 partnerâs 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 personâs 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
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 (Ï
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
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 <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
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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