scholarly journals Harnessing stratospheric diffusion barriers for enhanced climate geoengineering

2021 ◽  
Vol 21 (11) ◽  
pp. 8845-8861
Author(s):  
Nikolas O. Aksamit ◽  
Ben Kravitz ◽  
Douglas G. MacMartin ◽  
George Haller
Keyword(s):  
Radiative Forcing ◽  
Diffusion Barriers ◽  
Sulfate Aerosol ◽  
Shortwave Radiation ◽  
Great Promise ◽  
Time Varying ◽  
Material Transport ◽  
Transport Barriers ◽  
Aerosol Dispersion

Abstract. Stratospheric sulfate aerosol geoengineering is a proposed method to temporarily intervene in the climate system to increase the reflectance of shortwave radiation and reduce mean global temperature. In previous climate modeling studies, choosing injection locations for geoengineering aerosols has, thus far, only utilized the average dynamics of stratospheric wind fields instead of accounting for the essential role of time-varying material transport barriers in turbulent atmospheric flows. Here we conduct the first analysis of sulfate aerosol dispersion in the stratosphere, comparing what is now a standard fixed-injection scheme with time-varying injection locations that harness short-term stratospheric diffusion barriers. We show how diffusive transport barriers can quickly be identified, and we provide an automated injection location selection algorithm using short forecast and reanalysis data. Within the first 7 d days of transport, the dynamics-based approach is able to produce particle distributions with greater global coverage than fixed-site methods with fewer injections. Additionally, this enhanced dispersion slows aerosol microphysical growth and can reduce the effective radii of aerosols up to 200–300 d after injection. While the long-term dynamics of aerosol dispersion are accurately predicted with transport barriers calculated from short forecasts, the long-term influence on radiative forcing is more difficult to predict and warrants deeper investigation. Statistically significant changes in radiative forcing at timescales beyond the forecasting window showed mixed results, potentially increasing or decreasing forcing after 1 year when compared to fixed injections. We conclude that future feasibility studies of geoengineering should consider the cooling benefits possible by strategically injecting sulfate aerosols at optimized time-varying locations. Our method of utilizing time-varying attracting and repelling structures shows great promise for identifying optimal dispersion locations, and radiative forcing impacts can be improved by considering additional meteorological variables.

scholarly journals Harnessing Stratospheric Diffusion Barriers for Enhanced Climate Geoengineering

2020 ◽  
Author(s):  
Nikolas O. Aksamit ◽  
Ben Kravitz ◽  
Douglas G. MacMartin ◽  
George Haller
Keyword(s):  
Climate Modeling ◽  
Feasibility Studies ◽  
Reanalysis Data ◽  
Diffusion Barriers ◽  
Sulfate Aerosol ◽  
Shortwave Radiation ◽  
Time Varying ◽  
Wind Fields ◽  
Material Transport ◽  
Transport Barriers

Abstract. Stratospheric sulfate-aerosol geoengineering is a proposed method to temporarily intervene in the climate system to increase reflectance of shortwave radiation and reduce mean global temperature. In previous climate modeling studies, choosing injection locations for geoengineering aerosols has thus far only utilized average dynamics of stratospheric wind fields instead of accounting for the essential role of time-varying material transport barriers in turbulent atmospheric flows. Here we conduct the first analysis of sulfate aerosol dispersion in the stratosphere comparing a now-standard fixed-injection scheme with time-varying injection locations that harness short-term stratospheric diffusion barriers. We show how diffusive transport barriers can quickly be identified and inform optimal injection locations using short forecast and reanalysis data. Within the first seven days of transport, the dynamics-based approach is able to produce particle distributions with greater global coverage than fixed-site methods with fewer injections. Additionally, this enhanced dispersion slows aerosol microphysical growth, increasing lifespan of sulfate aerosols at monthly and yearly timescales. We conclude that previous feasibility studies of geoengineering likely underestimate the cooling efficiency of sulfate aerosol geoengineering.

Antithrombotic Therapy for DVT/PE

1997 ◽  
Vol 17 (03) ◽  
pp. 161-162
Author(s):  
Thomas Hyers
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Oral Anticoagulants ◽  
Cost Effective ◽  
Therapeutic Agents ◽  
Great Promise ◽  
Term Therapy ◽  
Low Molecular Weight ◽  
Long Term Therapy

SummaryProblems with unfractionated heparin as an antithrombotic have led to the development of new therapeutic agents. Of these, low molecular weight heparin shows great promise and has led to out-patient therapy of DVT/PE in selected patients. Oral anticoagulants remain the choice for long-term therapy. More cost-effective ways to give oral anticoagulants are needed.

Antiplatelet Therapy in Acute Coronary Syndromes

2010 ◽  
Vol 6 (1) ◽  
pp. 58
Author(s):  
Sasha Koul ◽  
David Erlinge ◽  
◽  
Keyword(s):  
Platelet Function ◽  
Acute Coronary Syndromes ◽  
New Drugs ◽  
Antiplatelet Drugs ◽  
Bleeding Complications ◽  
Great Promise ◽  
Mortality Data ◽  
Poor Responders ◽  
Coronary Syndromes

Drugs inhibiting platelet function play a major role in the treatment of acute coronary syndromes (ACS). The first drug used, which is still considered the cornerstone of therapy today, is aspirin. Although very impressive in acutely decreasing rates of myocardial infarction as well as death, long-term data are scarce, despite our current recommendation for lifelong aspirin. The thienopyridines, most notably clopidogrel, are the next line of antiplatelet drugs. Well-documented data support the usage of clopidogrel for non-STEMI-ACS (NSTE-ACS). Although positive mortality data exist regarding clopidogrel and STEMI patients in a medically treated population, including thrombolysis, no larger amounts of randomised data exist in a primary PCI setting. Poor responders to aspirin and/or clopidogrel are a clinical problem, with these individuals constituting a higherrisk group for recurrent ischaemic events. Whereas very little can be done regarding aspirin resistance, clopidogrel resistance might be diminished by increasing the dosage or changing to more potent and newer-generation antiplatelet drugs. The role of glycoprotein IIb/IIIa inhibitors has diminished drastically and instead paved the way for thrombin antagonists (bivalirudin), which have fewer bleeding complications with resulting better long-term mortality. Novel adenosine diphosphate (ADP)-receptor blockers such as prasugrel and ticagrelor have shown increased efficacy over clopidogrel and hold great promise for the future. However, not all patients may benefit from these new drugs and economic constraints may also limit their use. Platelet function tests could possibly help in identifying risk groups in need of stronger platelet inhibition.

Economic Institutions and Growth Nexus: The Role of Governance and Democratic Institutions—Evidence from Time Varying Parameters’ (TVPs) Models

2016 ◽  
Vol 55 (4I-II) ◽  
pp. 675-688
Author(s):  
Ghulam Murtaza ◽  
Muhammad Zahir Faridi
Keyword(s):  
Structural Changes ◽  
Jel Classification ◽  
Economic Institutions ◽  
Time Varying ◽  
Democratic Institutions ◽  
Main Hypothesis ◽  
Dynamic Relationship ◽  
Rolling Window

The present study has investigated the channels through which the linkage between economic institutions and growth is gauged, by addressing the main hypothesis of the study that whether quality of governance and democratic institutions set a stage for economic institutions to promote the long-term growth process in Pakistan. To test the hypothesis empirically, our study models the dynamic relationship between growth and economic institutions in a time varying framework in order to capture institutional developments and structural changes occurred in the economy of Pakistan over the years. Study articulates that, along with some customary specifics, the quality of government and democracy are the substantial factors that affect institutional quality and ultimately cause to promote growth in Pakistan. JEL Classification: O40; P16; C14; H10 Keywords: Economic Institutions, Growth, Governance and Democracy, Rolling Window Two-stage Least Squares, Pakistan

scholarly journals Applications, challenges, and needs for employing synthetic biology beyond the lab

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sierra M. Brooks ◽  
Hal S. Alper
Keyword(s):  
Synthetic Biology ◽  
Great Promise ◽  
Long Term Storage ◽  
Autonomous Function ◽  
Recent Advances ◽  
Resource Limited ◽  
Major Application ◽  
Further Development ◽  
Probiotic Delivery

AbstractSynthetic biology holds great promise for addressing global needs. However, most current developments are not immediately translatable to ‘outside-the-lab’ scenarios that differ from controlled laboratory settings. Challenges include enabling long-term storage stability as well as operating in resource-limited and off-the-grid scenarios using autonomous function. Here we analyze recent advances in developing synthetic biological platforms for outside-the-lab scenarios with a focus on three major application spaces: bioproduction, biosensing, and closed-loop therapeutic and probiotic delivery. Across the Perspective, we highlight recent advances, areas for further development, possibilities for future applications, and the needs for innovation at the interface of other disciplines.

scholarly journals Activation of the receptor tyrosine kinase RET improves long-term hematopoietic stem cell outgrowth and potency

Blood ◽  
2020 ◽  
Vol 136 (22) ◽  
pp. 2535-2547 ◽  
Author(s):  
W. Grey ◽  
R. Chauhan ◽  
M. Piganeau ◽  
H. Huerga Encabo ◽  
M. Garcia-Albornoz ◽  
...  
Keyword(s):  
Intracellular Signaling ◽  
Culture Conditions ◽  
Cellular Growth ◽  
Great Promise ◽  
Bone Marrow Niche ◽  
Hematopoietic Stem ◽  
Intracellular Signaling Pathway ◽  
Wide Range

Abstract Expansion of human hematopoietic stem cells (HSCs) is a rapidly advancing field showing great promise for clinical applications. Recent evidence has implicated the nervous system and glial family ligands (GFLs) as potential drivers of hematopoietic survival and self-renewal in the bone marrow niche; how to apply this process to HSC maintenance and expansion has yet to be explored. We show a role for the GFL receptor, RET, at the cell surface of HSCs in mediating sustained cellular growth, resistance to stress, and improved cell survival throughout in vitro expansion. HSCs treated with the key RET ligand/coreceptor complex, glial-derived neurotrophic factor and its coreceptor, exhibit improved progenitor function at primary transplantation and improved long-term HSC function at secondary transplantation. Finally, we show that RET drives a multifaceted intracellular signaling pathway, including key signaling intermediates protein kinase B, extracellular signal-regulated kinase 1/2, NF-κB, and p53, responsible for a wide range of cellular and genetic responses that improve cell growth and survival under culture conditions.

scholarly journals Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo

2011 ◽  
Vol 11 (14) ◽  
pp. 7155-7170 ◽  
Author(s):  
Y. Liu ◽  
W. Wu ◽  
M. P. Jensen ◽  
T. Toto
Keyword(s):  
Radiative Forcing ◽  
Climate Models ◽  
Cloud Fraction ◽  
Shortwave Radiation ◽  
Cloud Radiative Forcing ◽  
Analytical Expression ◽  
Cloud Albedo ◽  
Annual Variations ◽  
Hourly Data ◽  
Radiation Parameterizations

Abstract. This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surface-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fraction, and cloud albedo. The analytical expression is then used to deduce a new approach for inferring cloud albedo from concurrent surface-based measurements of downwelling surface shortwave radiation and cloud fraction. High-resolution decade-long data on cloud albedos are obtained by use of this surface-based approach over the US Department of Energy's Atmospheric Radiaton Measurement (ARM) Program at the Great Southern Plains (SGP) site. The surface-based cloud albedos are further compared against those derived from the coincident GOES satellite measurements. The three long-term (1997–2009) sets of hourly data on shortwave cloud radiative forcing, cloud fraction and cloud albedo collected over the SGP site are analyzed to explore the multiscale (diurnal, annual and inter-annual) variations and covariations. The analytical formulation is useful for diagnosing deficiencies of cloud-radiation parameterizations in climate models.

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