5,212 research outputs found

    Intercomparisons of airborne measurements of aerosol ionic chemical composition during TRACE-P and ACE-Asia

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    As part of the two field studies, Transport and Chemical Evolution over the Pacific (TRACE-P) and the Asian Aerosol Characterization Experiment (ACE-Asia), the inorganic chemical composition of tropospheric aerosols was measured over the western Pacific from three separate aircraft using various methods. Comparisons are made between the rapid online techniques of the particle into liquid sampler (PILS) for measurement of a suite of fine particle a mist chamber/ion chromatograph (MC/IC) measurement of fine sulfate, and the longer time-integrated filter and micro-orifice impactor (MOI) measurements. Comparisons between identical PILS on two separate aircraft flying in formation showed that they were highly correlated (e.g., sulfate r2 of 0.95), but were systematically different by 10 ± 5% (linear regression slope and 95% confidence bounds), and had generally higher concentrations on the aircraft with a low-turbulence inlet and shorter inlet-to-instrument transmission tubing. Comparisons of PILS and mist chamber measurements of fine sulfate on two different aircraft during formation flying had an r 2 of 0.78 and a relative difference of 39% ± 5%. MOI ionic data integrated to the PILS upper measurement size of 1.3 mm sampling from separate inlets on the same aircraft showed that for sulfate, PILS and MOI were within 14% ± 6% and correlated with an r 2 of 0.87. Most ionic compounds were within ±30%, which is in the range of differences reported between PILS and integrated samplers from ground-based comparisons. In many cases, direct intercomparison between the various instruments is difficult due to differences in upper-size detection limits. However, for this study, the results suggest that the fine particle mass composition measured from aircraft agree to within 30–40%

    Medicaid eligibility loss among dual-eligible beneficiaries before and during COVID-19 public health emergency

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    IMPORTANCE: Medicaid coverage loss can substantially compromise access to and affordability of health care for dual-eligible beneficiaries. The extent to which this population lost Medicaid coverage before and during the COVID-19 public health emergency (PHE) and the characteristics of beneficiaries more at risk for coverage loss are currently not well known. OBJECTIVE: To assess the loss of Medicaid coverage among dual-eligible beneficiaries before and during the first year of the PHE, and to examine beneficiary-level and plan-level factors associated with heightened likelihood of losing Medicaid. DESIGN, SETTING, AND PARTICIPANTS: This repeated cross-sectional study used national Medicare data to estimate annual rates of Medicaid loss among dual-eligible beneficiaries before (2015 to 2019) and during the PHE (2020). Individuals who were dual eligible for Medicare and Medicaid at the beginning of a given year and who continuously received low-income subsidies for Medicare Part D prescription drug coverage were included in the sample. Multivariable regression models were used to examine beneficiary-level and plan-level factors associated with Medicaid loss. Data analyses were conducted between March 2023 and October 2023. EXPOSURE: Onset of PHE. MAIN OUTCOMES AND MEASURES: Loss of Medicaid for at least 1 month within a year. RESULTS: Sample included 56 172 736 dual-eligible beneficiary-years between 2015 and 2020. In 2020, most dual-eligible beneficiaries were aged over 65 years (5 984 420 [61.1%]), female (5 868 866 [59.9%]), non-Hispanic White (4 928 035 [50.3%]), full-benefit eligible (6 837 815 [69.8%]), and enrolled in traditional Medicare (5 343 537 [54.6%]). The adjusted proportion of dual-eligible beneficiaries losing Medicaid for at least 1 month increased from 6.6% in 2015 to 7.3% in 2019 and then dropped to 2.3% in 2020. Between 2015 and 2019, dual-eligible beneficiaries who were older (ages 55-64 years: -1.4%; 95% CI, -1.8% to -1.0%; ages 65-74 years: -2.0%; 95% CI, -2.5% to -1.5%; ages 75 and older: -4.5%; 95% CI, -5.0% to -4.0%), disabled (-0.8%; 95% CI, -1.1% to -0.6%), and in integrated care programs were less likely to lose Medicaid. In 2020, the disparities within each of these demographic groups narrowed significantly. Notably, while Black (0.6%; 95% CI, 0.2% to 0.9%) and Hispanic (0.7%; 95% CI, 0.3% to 1.2%) dual-eligible beneficiaries were more likely to lose Medicaid than their non-Hispanic White counterparts between 2015 and 2019, such gap was eliminated for Black beneficiaries and narrowed for Hispanic beneficiaries in 2020. CONCLUSIONS AND RELEVANCE: During the PHE, Medicaid coverage loss declined significantly among dual-eligible beneficiaries, and disparities were mitigated across subgroups. As the PHE unwinds, it is crucial for policymakers to implement strategies to minimize Medicaid coverage disruptions and racial and ethnic disparities, especially given that loss of Medicaid was slightly increasing over time before the PHE

    Dimensional Regularization in Quarkonium Calculations

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    Dimensional regularization is incompatible with the standard covariant projection methods that are used to calculate the short-distance coefficients in inclusive heavy quarkonium production and annihilation rates. A new method is developed that allows dimensional regularization to be used consistently to regularize the infrared and ultraviolet divergences that arise in these perturbative calculations. We illustrate the method by calculating the leading color-octet terms and the leading color-singlet terms in the gluon fragmentation functions for arbitrary quarkonium states. We resolve a discrepancy between two previous calculations of the gluon fragmentation functions for the spin-triplet P-wave quarkonium states

    Capacitive Sensing of Intercalated H2O Molecules Using Graphene

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    Understanding the interactions of ambient molecules with graphene and adjacent dielectrics is of fundamental importance for a range of graphene-based devices, particularly sensors, where such interactions could influence the operation of the device. It is well-known that water can be trapped underneath graphene and its host substrate, however, the electrical effect of water beneath graphene and the dynamics of how it changes with different ambient conditions has not been quantified. Here, using a metal-oxide-graphene variable-capacitor (varactor) structure, we show that graphene can be used to capacitively sense the intercalation of water between graphene and HfO2 and that this process is reversible on a fast time scale. Atomic force microscopy is used to confirm the intercalation and quantify the displacement of graphene as a function of humidity. Density functional theory simulations are used to quantify the displacement of graphene induced by intercalated water and also explain the observed Dirac point shifts as being due to the combined effect of water and oxygen on the carrier concentration in the graphene. Finally, molecular dynamics simulations indicate that a likely mechanism for the intercalation involves adsorption and lateral diffusion of water molecules beneath the graphene.Comment: E.J.O. and R.M. made an equal contribution to this wor

    KELT-3b: A Hot Jupiter Transiting A V=9.8 Late-F Star

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    We report the discovery of KELT-3b, a moderately inflated transiting hot Jupiter with a mass of 1.477(-0.067)(+0.066) M-J, radius of 1.345 +/- 0.072 R-J, and an orbital period of 2.7033904 +/- 0.000010 days. The host star, KELT-3, is a V = 9.8 late F star with M-* = 1.278(-0.061)(+0.063) M-circle dot, R-* = 1.472(-0.067)(+0.065) R-circle dot, T-eff = 6306(-49)(+50) K, log(g) = 4.209(-0.031)(+0.033), and [Fe/H] = 0.044(-0.082)(+0.080), and has a likely proper motion companion. KELT-3b is the third transiting exoplanet discovered by the KELT survey, and is orbiting one of the 20 brightest known transiting planet host stars, making it a promising candidate for detailed characterization studies. Although we infer that KELT-3 is significantly evolved, a preliminary analysis of the stellar and orbital evolution of the system suggests that the planet has likely always received a level of incident flux above the empirically identified threshold for radius inflation suggested by Demory & Seager

    Thalamic GABA levels and Occupational Manganese Neurotoxicity: Association with Exposure Levels and Brain MRI

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    Excessive occupational exposure to Manganese (Mn) has been associated with clinical symptoms resembling idiopathic Parkinson’s disease (IPD), impairing cognitive and motor functions. Several studies point towards an involvement of the brain neurotransmitter system in Mn intoxication, which is hypothesized to be disturbed prior to onset of symptoms. Edited Magnetic Resonance Spectroscopy (MRS) offers the unique possibility to measure γ-amminobutyric acid (GABA) and other neurometabolites in vivo non-invasively in workers exposed to Mn. In addition, the property of Mn as Magnetic Resonance Imaging (MRI) contrast agent may be used to study Mn deposition in the human brain. In this study, using MRI, MRS, personal air sampling at the working place, work history questionnaires, and neurological assessment (UPDRS-III), the effects of chronic Mn exposure on the thalamic GABAergic system was studied in a group of welders (N = 39) with exposure to Mn fumes in a typical occupational setting. Two subgroups of welders with different exposure levels (Low: N = 26; mean air Mn = 0.13 ± 0.1 mg/m3; High: N = 13; mean air Mn = 0.23 ± 0.18 mg/m3), as well as unexposed control workers (N = 22, mean air Mn = 0.002 ± 0.001 mg/m3) were recruited. The group of welders with higher exposure showed a significant increase of thalamic GABA levels by 45% (p < 0.01, F(1,33) = 9.55), as well as significantly worse performance in general motor function (p < 0.01, F(1,33) = 11.35). However, welders with lower exposure did not differ from the controls in GABA levels or motor performance. Further, in welders the thalamic GABA levels were best predicted by past-12-months exposure levels and were influenced by the Mn deposition in the substantia nigra and globus pallidus. Importantly, both thalamic GABA levels and motor function displayed a non-linear pattern of response to Mn exposure, suggesting a threshold effect
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