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  • 1
    In: Biogeosciences, Copernicus GmbH, Vol. 20, No. 10 ( 2023-05-26), p. 1937-1961
    Abstract: Abstract. Multiple climate-driven stressors, including warming and increased nutrient delivery, are exacerbating hypoxia in coastal marine environments. Within coastal watersheds, environmental managers are particularly interested in climate impacts on terrestrial processes, which may undermine the efficacy of management actions designed to reduce eutrophication and consequent low-oxygen conditions in receiving coastal waters. However, substantial uncertainty accompanies the application of Earth system model (ESM) projections to a regional modeling framework when quantifying future changes to estuarine hypoxia due to climate change. In this study, two downscaling methods are applied to multiple ESMs and used to force two independent watershed models for Chesapeake Bay, a large coastal-plain estuary of the eastern United States. The projected watershed changes are then used to force a coupled 3-D hydrodynamic–biogeochemical estuarine model to project climate impacts on hypoxia, with particular emphasis on projection uncertainties. Results indicate that all three factors (ESM, downscaling method, and watershed model) are found to contribute substantially to the uncertainty associated with future hypoxia, with the choice of ESM being the largest contributor. Overall, in the absence of management actions, there is a high likelihood that climate change impacts on the watershed will expand low-oxygen conditions by 2050 relative to a 1990s baseline period; however, the projected increase in hypoxia is quite small (4 %) because only climate-induced changes in watershed inputs are considered and not those on the estuary itself. Results also demonstrate that the attainment of established nutrient reduction targets will reduce annual hypoxia by about 50 % compared to the 1990s. Given these estimates, it is virtually certain that fully implemented management actions reducing excess nutrient loadings will outweigh hypoxia increases driven by climate-induced changes in terrestrial runoff.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2023
    detail.hit.zdb_id: 2158181-2
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  • 2
    Online Resource
    Online Resource
    American Geophysical Union (AGU) ; 2021
    In:  Journal of Geophysical Research: Oceans Vol. 126, No. 6 ( 2021-06)
    In: Journal of Geophysical Research: Oceans, American Geophysical Union (AGU), Vol. 126, No. 6 ( 2021-06)
    Abstract: Decadal changes in estuarine surface pH and aragonite saturation state (Ω AR ) exhibit large spatial and seasonal variability In the upper Chesapeake Bay, changes in riverine alkalinity and dissolved inorganic carbon have increased surface pH in fall and spring In the mid‐ and lower Bay, higher atmospheric CO 2 and reduced nutrient loading have (nearly equally) reduced surface pH and Ω AR in summer
    Type of Medium: Online Resource
    ISSN: 2169-9275 , 2169-9291
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2021
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    detail.hit.zdb_id: 161667-5
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    SSG: 16,13
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  • 3
    Online Resource
    Online Resource
    Copernicus GmbH ; 2018
    In:  Biogeosciences Vol. 15, No. 9 ( 2018-05-04), p. 2649-2668
    In: Biogeosciences, Copernicus GmbH, Vol. 15, No. 9 ( 2018-05-04), p. 2649-2668
    Abstract: Abstract. The Chesapeake Bay region is projected to experience changes in temperature, sea level, and precipitation as a result of climate change. This research uses an estuarine-watershed hydrodynamic–biogeochemical modeling system along with projected mid-21st-century changes in temperature, freshwater flow, and sea level rise to explore the impact climate change may have on future Chesapeake Bay dissolved-oxygen (DO) concentrations and the potential success of nutrient reductions in attaining mandated estuarine water quality improvements. Results indicate that warming bay waters will decrease oxygen solubility year-round, while also increasing oxygen utilization via respiration and remineralization, primarily impacting bottom oxygen in the spring. Rising sea level will increase estuarine circulation, reducing residence time in bottom waters and increasing stratification. As a result, oxygen concentrations in bottom waters are projected to increase, while oxygen concentrations at mid-depths (3 〈 DO 〈 5 mg L−1) will typically decrease. Changes in precipitation are projected to deliver higher winter and spring freshwater flow and nutrient loads, fueling increased primary production. Together, these multiple climate impacts will lower DO throughout the Chesapeake Bay and negatively impact progress towards meeting water quality standards associated with the Chesapeake Bay Total Maximum Daily Load. However, this research also shows that the potential impacts of climate change will be significantly smaller than improvements in DO expected in response to the required nutrient reductions, especially at the anoxic and hypoxic levels. Overall, increased temperature exhibits the strongest control on the change in future DO concentrations, primarily due to decreased solubility, while sea level rise is expected to exert a small positive impact and increased winter river flow is anticipated to exert a small negative impact.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2018
    detail.hit.zdb_id: 2158181-2
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  • 4
    Online Resource
    Online Resource
    Wiley ; 2022
    In:  JAWRA Journal of the American Water Resources Association Vol. 58, No. 6 ( 2022-12), p. 805-825
    In: JAWRA Journal of the American Water Resources Association, Wiley, Vol. 58, No. 6 ( 2022-12), p. 805-825
    Abstract: Coastal environments such as the Chesapeake Bay have long been impacted by eutrophication stressors resulting from human activities, and these impacts are now being compounded by global warming trends. However, there are few studies documenting long‐term estuarine temperature change and the relative contributions of rivers, the atmosphere, and the ocean. In this study, Chesapeake Bay warming, since 1985, is quantified using a combination of cruise observations and model outputs, and the relative contributions to that warming are estimated via numerical sensitivity experiments with a watershed–estuarine modeling system. Throughout the Bay’s main stem, similar warming rates are found at the surface and bottom between the late 1980s and late 2010s (0.02 ± 0.02°C/year, mean ± 1 standard error), with elevated summer rates (0.04 ± 0.01°C/year) and lower rates of winter warming (0.01 ± 0.01°C/year). Most (~85%) of this estuarine warming is driven by atmospheric effects. The secondary influence of ocean warming increases with proximity to the Bay mouth, where it accounts for more than half of summer warming in bottom waters. Sea level rise has slightly reduced summer warming, and the influence of riverine warming has been limited to the heads of tidal tributaries. Future rates of warming in Chesapeake Bay will depend not only on global atmospheric trends, but also on regional circulation patterns in mid‐Atlantic waters, which are currently warming faster than the atmosphere.
    Type of Medium: Online Resource
    ISSN: 1093-474X , 1752-1688
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2090051-X
    SSG: 14
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  • 5
    In: JAMA, American Medical Association (AMA), Vol. 325, No. 8 ( 2021-02-23), p. 742-
    Type of Medium: Online Resource
    ISSN: 0098-7484
    RVK:
    Language: English
    Publisher: American Medical Association (AMA)
    Publication Date: 2021
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    SSG: 5,21
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  • 6
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 378, No. 6615 ( 2022-10-07)
    Abstract: Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century. Expanse of SARS-CoV-2 sequencing capacity in Africa. ( A ) African countries (shaded in gray) and institutions (red circles) with on-site sequencing facilities that are capable of producing SARS-CoV-2 whole genomes locally. ( B ) The number of SARS-CoV-2 genomes produced per country and the proportion of those genomes that were produced locally, regionally within Africa, or abroad. ( C ) Decreased turnaround time of sequencing output in Africa to an almost real-time release of genomic data.
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
    RVK:
    RVK:
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2022
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    detail.hit.zdb_id: 2066996-3
    detail.hit.zdb_id: 2060783-0
    SSG: 11
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  • 7
    In: JAMA Ophthalmology, American Medical Association (AMA), Vol. 141, No. 3 ( 2023-03-01), p. 268-
    Abstract: The DRCR Retina Network Protocol AC showed no significant difference in visual acuity outcomes over 2 years between treatment with aflibercept monotherapy and bevacizumab first with switching to aflibercept for suboptimal response in treating diabetic macular edema (DME). Understanding the estimated cost and cost-effectiveness of these approaches is important. Objective To evaluate the cost and cost-effectiveness of aflibercept monotherapy vs bevacizumab-first strategies for DME treatment. Design, Setting, and Participants This economic evaluation was a preplanned secondary analysis of a US randomized clinical trial of participants aged 18 years or older with center-involved DME and best-corrected visual acuity of 20/50 to 20/320 enrolled from December 15, 2017, through November 25, 2019. Interventions Aflibercept monotherapy or bevacizumab first, switching to aflibercept in eyes with protocol-defined suboptimal response. Main Outcomes and Measures Between February and July 2022, the incremental cost-effectiveness ratio (ICER) in cost per quality-adjusted life-year (QALY) over 2 years was assessed. Efficacy and resource utilization data from the randomized clinical trial were used with health utility mapping from the literature and Medicare unit costs. Results This study included 228 participants (median age, 62 [range, 34-91 years; 116 [51%] female and 112 [49%] male; 44 [19%] Black or African American, 60 [26%] Hispanic or Latino, and 117 [51%] White) with 1 study eye. The aflibercept monotherapy group included 116 participants, and the bevacizumab-first group included 112, of whom 62.5% were eventually switched to aflibercept. Over 2 years, the cost of aflibercept monotherapy was $26 504 (95% CI, $24 796-$28 212) vs $13 929 (95% CI, $11 984-$15 874) for the bevacizumab-first group, a difference of $12 575 (95% CI, $9987-$15 163). The aflibercept monotherapy group gained 0.015 (95% CI, −0.011 to 0.041) QALYs using the better-seeing eye and had an ICER of $837 077 per QALY gained compared with the bevacizumab-first group. Aflibercept could be cost-effective with an ICER of $100 000 per QALY if the price per dose were $305 or less or the price of bevacizumab was $1307 per dose or more. Conclusions and Relevance Variability in individual needs will influence clinician and patient decisions about how to treat specific eyes with DME. While the bevacizumab-first group costs still averaged approximately $14 000 over 2 years, this approach, as used in this study, may confer substantial cost savings on a societal level without sacrificing visual acuity gains over 2 years compared with aflibercept monotherapy.
    Type of Medium: Online Resource
    ISSN: 2168-6165
    Language: English
    Publisher: American Medical Association (AMA)
    Publication Date: 2023
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  • 8
    In: JAMA Network Open, American Medical Association (AMA), Vol. 6, No. 2 ( 2023-02-28), p. e230380-
    Abstract: Sepsis is associated with long-term cognitive impairment and worse psychological and functional outcomes. Potential mechanisms include intracerebral oxidative stress and inflammation, yet little is known about the effects of early antioxidant and anti-inflammatory therapy on cognitive, psychological, and functional outcomes in sepsis survivors. Objective To describe observed differences in long-term cognitive, psychological, and functional outcomes of vitamin C, thiamine, and hydrocortisone between the intervention and control groups in the Vitamin C, Thiamine, and Steroids in Sepsis (VICTAS) randomized clinical trial. Design, Setting, and Participants This prespecified secondary analysis reports the 6-month outcomes of the multicenter, double-blind, placebo-controlled VICTAS randomized clinical trial, which was conducted between August 2018 and July 2019. Adult patients with sepsis-induced respiratory and/or cardiovascular dysfunction who survived to discharge or day 30 were recruited from 43 intensive care units in the US. Participants were randomized 1:1 to either the intervention or control group. Cognitive, psychological, and functional outcomes at 6 months after randomization were assessed via telephone through January 2020. Data analyses were conducted between February 2021 and December 2022. Interventions The intervention group received intravenous vitamin C (1.5 g), thiamine hydrochloride (100 mg), and hydrocortisone sodium succinate (50 mg) every 6 hours for 96 hours or until death or intensive care unit discharge. The control group received matching placebo. Main Outcomes and Measures Cognitive performance, risk of posttraumatic stress disorder and depression, and functional status were assessed using a battery of standardized instruments that were administered during a 1-hour telephone call 6 months after randomization. Results After exclusions, withdrawals, and deaths, the final sample included 213 participants (median [IQR] age, 57 [47-67] years; 112 males [52.6%]) who underwent long-term outcomes assessment and had been randomized to either the intervention group (n = 108) or control group (n = 105). The intervention group had lower immediate memory scores (adjusted OR [aOR] , 0.49; 95% CI, 0.26-0.89), higher odds of posttraumatic stress disorder (aOR, 3.51; 95% CI, 1.18-10.40), and lower odds of receiving mental health care (aOR, 0.38; 95% CI, 0.16-0.89). No other statistically significant differences in cognitive, psychological, and functional outcomes were found between the 2 groups. Conclusions and Relevance In survivors of sepsis, treatment with vitamin C, thiamine, and hydrocortisone did not improve or had worse cognitive, psychological, and functional outcomes at 6 months compared with patients who received placebo. These findings challenge the hypothesis that antioxidant and anti-inflammatory therapy during critical illness mitigates the development of long-term cognitive, psychological, and functional impairment in sepsis survivors. Trial Registration ClinicalTrials.gov Identifier: NCT03509350
    Type of Medium: Online Resource
    ISSN: 2574-3805
    Language: English
    Publisher: American Medical Association (AMA)
    Publication Date: 2023
    detail.hit.zdb_id: 2931249-8
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