scholarly journals Can we explain the observed methane variability after the Mount Pinatubo eruption?

2015 ◽  
Vol 15 (13) ◽  
pp. 19111-19160
Author(s):  
N. Bândă ◽  
M. Krol ◽  
M. van Weele ◽  
T. van Noije ◽  
P. Le Sager ◽  
...  
Keyword(s):  
Growth Rate ◽  
Biomass Burning ◽  
Partial Recovery ◽  
Mount Pinatubo ◽  
Sources And Sinks ◽  
Time Period ◽  
Pinatubo Eruption ◽  
Emission Changes

Abstract. The CH4 growth rate in the atmosphere showed large variations after the Pinatubo eruption in June 1991. A decrease of more than 10 ppb yr-1 in the growth rate over the course of 1992 was reported and a partial recovery in the following year. Although several reasons have been proposed to explain the evolution of CH4 after the eruption, their contributions to the observed variations are not yet resolved. CH4 is removed from the atmosphere by the reaction with tropospheric OH, which in turn is produced by O3 photolysis under UV radiation. The CH4 removal after the Pinatubo eruption might have been affected by changes in tropospheric UV levels due to the presence of stratospheric SO2 and sulfate aerosols, and due to enhanced ozone depletion on Pinatubo aerosols. The perturbed climate after the eruption also altered both sources and sinks of atmospheric CH4. Furthermore, CH4 concentrations were influenced by other factors of natural variability in that period, such as ENSO and biomass burning events. Emissions of CO, NOX and NMVOCs also affected CH4 concentrations indirectly by influencing tropospheric OH levels. Potential drivers of CH4 variability are investigated using the TM5 global chemistry model. The contribution that each driver had to the global CH4 variability during the period 1990 to 1995 is quantified. We find that a decrease of 8–10 ppb yr-1 CH4 is explained by a combination of the above processes. However, the timing of the minimum growth rate is found 6–9 months later than observed. The long-term decrease in CH4 growth rate over the period 1990 to 1995 is well captured and can be attributed to an increase in OH concentrations over this time period. Potential uncertainties in our modelled CH4 growth rate include emissions of CH4 from wetlands, biomass burning emissions of CH4 and other compounds, biogenic NMVOC and the sensitivity of OH to NMVOC emission changes. Two inventories are used for CH4 emissions from wetlands, ORCHIDEE and LPJ, to investigate the role of uncertainties in these emissions. Although the higher climate sensitivity of ORCHIDEE improves the simulated CH4 growth rate change after Pinatubo, none of the two inventories properly captures the observed CH4 variability in this period.

scholarly journals Can we explain the observed methane variability after the Mount Pinatubo eruption?

2016 ◽  
Vol 16 (1) ◽  
pp. 195-214 ◽  
Author(s):  
N. Bândă ◽  
M. Krol ◽  
M. van Weele ◽  
T. van Noije ◽  
P. Le Sager ◽  
...  
Keyword(s):  
Growth Rate ◽  
Biomass Burning ◽  
Southern Oscillation ◽  
Partial Recovery ◽  
Sources And Sinks ◽  
Time Period ◽  
Pinatubo Eruption ◽  
Emission Changes

Abstract. The CH4 growth rate in the atmosphere showed large variations after the Pinatubo eruption in June 1991. A decrease of more than 10 ppb yr−1 in the growth rate over the course of 1992 was reported, and a partial recovery in the following year. Although several reasons have been proposed to explain the evolution of CH4 after the eruption, their contributions to the observed variations are not yet resolved. CH4 is removed from the atmosphere by the reaction with tropospheric OH, which in turn is produced by O3 photolysis under UV radiation. The CH4 removal after the Pinatubo eruption might have been affected by changes in tropospheric UV levels due to the presence of stratospheric SO2 and sulfate aerosols, and due to enhanced ozone depletion on Pinatubo aerosols. The perturbed climate after the eruption also altered both sources and sinks of atmospheric CH4. Furthermore, CH4 concentrations were influenced by other factors of natural variability in that period, such as El Niño–Southern Oscillation (ENSO) and biomass burning events. Emissions of CO, NOX and non-methane volatile organic compounds (NMVOCs) also affected CH4 concentrations indirectly by influencing tropospheric OH levels.Potential drivers of CH4 variability are investigated using the TM5 global chemistry model. The contribution that each driver had to the global CH4 variability during the period 1990 to 1995 is quantified. We find that a decrease of 8–10 ppb yr−1 CH4 is explained by a combination of the above processes. However, the timing of the minimum growth rate is found 6&nash;9 months later than observed. The long-term decrease in CH4 growth rate over the period 1990 to 1995 is well captured and can be attributed to an increase in OH concentrations over this time period. Potential uncertainties in our modelled CH4 growth rate include emissions of CH4 from wetlands, biomass burning emissions of CH4 and other compounds, biogenic NMVOC and the sensitivity of OH to NMVOC emission changes. Two inventories are used for CH4 emissions from wetlands, ORCHIDEE and LPJ, to investigate the role of uncertainties in these emissions. Although the higher climate sensitivity of ORCHIDEE improves the simulated CH4 growth rate change after Pinatubo, none of the two inventories properly captures the observed CH4 variability in this period.

ON THE CONSUMPTION/DISTRIBUTION THEOREM UNDER THE LONG-RUN GROWTH CRITERION SUBJECT TO A DRAWDOWN CONSTRAINT

2010 ◽  
Vol 13 (06) ◽  
pp. 931-957 ◽  
Author(s):  
MICHAEL J. KLASS ◽  
KRZYSZTOF NOWICKI
Keyword(s):  
Growth Rate ◽  
Short Term ◽  
Long Run ◽  
Time Period ◽  
Total Capital ◽  
Growth Criterion ◽  
Drawdown Constraint ◽  
Riskless Asset ◽  
Distribution Theorem

Consider any discrete time sequence of investment fortunes Fn which has a finite long-run growth rate [Formula: see text] when subject to the present value capital drawdown constraint Fne-rn ≥ λ* max 0≤k≤nFke-rk, where 0 ≤ λ* < 1, in the presence of a riskless asset affording a return of er dollars per time period per dollar invested. We show that money can be withdrawn for consumption from the invested capital without either reducing the long-run growth rate of such capital or violating the drawdown constraint for our capital sequence, while simultaneously increasing the amount of capital withdrawn for consumption at the identical long-term rate of V(r, λ*). We extend this result to an exponentially increasing number of consumption categories and discuss how additional yearly contributions can temporarily augment the total capital under management. In addition, we assess the short-term practicality of creating such an endowment/consumption/distribution program.

Long-term observations of the midlatitude stratospheric aerosol from the Mount Pinatubo eruption

1996 ◽  
Author(s):  
David C. Woods ◽  
David M. Winker ◽  
Otto Youngbluth, Jr. ◽  
Mary T. Osborn ◽  
Robert J. DeCoursey
Keyword(s):  
Stratospheric Aerosol ◽  
Mount Pinatubo ◽  
Pinatubo Eruption

scholarly journals Measuring the Effect of the Internet on Economic Growth: The Case of Saudi Arabia

2020 ◽  
Vol 12 (12) ◽  
pp. 61
Author(s):  
Hisham J. Bardesi
Keyword(s):  
Economic Growth ◽  
Growth Rate ◽  
Saudi Arabia ◽  
Internet Access ◽  
Ordinary Least Squares ◽  
The Internet ◽  
Macroeconomic Performance ◽  
The Impact

The purpose of this study is to examine and assess the impact of the Internet on economic growth in Saudi Arabia. Various studies show that there is a relationship between the growth rate of GDP and the Internet, as estimated by Internet user numbers. In this paper, the ordinary least squares (OLS) model is utilized to study the economic impact of Internet Access from 1994 to 2018, which has had a profound effect on the market structure of many sectors and Saudi&rsquo;s global macroeconomic performance. The study constructs a model to investigate any significant impact of the Internet on the Saudi economy. Finally, this paper suggests that an understanding of the role of the Internet is essential for policymakers who plan to promote new forms of economic growth in the future. To take a long-term view implies working on technologies that could improve the economy and people&rsquo;s lives by creating a technological ecosystem in and around Saudi Arabia, along with other major economies.

scholarly journals An analysis of atmospheric CH<sub>4</sub> concentrations from 1984 to 2008 with a single box atmospheric chemistry model

2012 ◽  
Vol 12 (11) ◽  
pp. 30259-30282 ◽  
Author(s):  
Z. Tan ◽  
Q. Zhuang
Keyword(s):  
Growth Rate ◽  
Atmospheric Chemistry ◽  
Methane Flux ◽  
Methane Emissions ◽  
Atmospheric Methane ◽  
Significant Drop ◽  
Oxidizing Power ◽  
The Mean

Abstract. We present a single box atmospheric chemistry model involving atmospheric methane (CH4), carbon monoxide (CO) and radical hydroxyl (OH) to analyze atmospheric CH4 concentrations from 1984 to 2008. When OH is allowed to vary, the modeled CH4 is 20 ppb higher than observations from the NOAA/ESRL and AGAGE networks for the end of 2008. However, when the OH concentration is held constant at 106 molecule cm−3, the simulated CH4 shows a trend approximately equal to observations. Both simulations show a clear slowdown in the CH4 growth rate during recent decades, from about 13 ppb yr−1 in 1984 to less than 5 ppb yr−1 in 2003. Furthermore, if the constant OH assumption is credible, we think that this slowdown is mainly due to a pause in the growth of wetland methane emissions. In simulations run for the Northern and Southern Hemispheres separately, we find that the Northern Hemisphere is more sensitive to wetland emissions, whereas the southern tends to be more perturbed by CH4 transportation, dramatic OH change, and biomass burning. When measured CO values from NOAA/ESRL are used to drive the model, changes in the CH4 growth rate become more consistent with observations, but the long-term increase in CH4 is underestimated. This shows that CO is a good indicator of short-term variations in oxidizing power in the atmosphere. The simulation results also indicate the significant drop in OH concentrations in 1998 (about 5% lower than the previous year) was probably due to an abrupt increase in wetland methane emissions during an intense EI Niño event. Using a fixed-lag Kalman smoother, we estimate the mean wetland methane flux is about 128 Tg yr−1 through the period 1984–2008. This study demonstrates the effectiveness in examining the role of OH and CO in affecting CH4.

scholarly journals The role of stj fimbrial operon in the intestinal persistence of Salmonella Typhimurium in mice

Biologia ◽  
2009 ◽  
Vol 64 (5) ◽  
Author(s):  
Nefise Akkoç ◽  
Banu Özden ◽  
Begüm Tan ◽  
Mustafa Akçelik
Keyword(s):  
Salmonella Typhimurium ◽  
Model System ◽  
Mesenteric Lymph Nodes ◽  
Resistant Mouse ◽  
Knock Out ◽  
Mesenteric Lymph ◽  
Time Period ◽  
Intestinal Persistence

AbstractSalmonella Typhimurium contains 13 operons coding for fimbriae with unique binding specificities to host epithelial surfaces. stj operon is only detected in S. Typhimurium genome suggesting that Stj fimbria may effect serovarspecific virulence characteristics. In this study, the role of stj fimbrial operon in the long-term persistence of S. Typhimurium was identified by competitive infection experiment in genetically resistant mouse (CBA) model system. Knock-out mutation of stjA (major subunit of the Stj fimbria) gene reduced recovery of S. Typhimurium from fecal samples and its colonization to spleen, cecum and mesenteric lymph nodes over a 34-day time period (p < 0.05). This data indicate that stj fimbrial operon has a role in long-term intestinal persistence of S. Typhimurium in CBA mice.

scholarly journals ANMCO POSITION PAPER: The role of cardiology in the management of the health needs in the post-Covid-19 era

2020 ◽  
Vol 22 (Supplement_G) ◽  
pp. G217-G222
Author(s):  
Adriano Murrone ◽  
Furio Colivicchi ◽  
Loris Roncon ◽  
Pasquale Caldarola ◽  
Vincenzo Amodeo ◽  
...  
Keyword(s):  
Structural Adjustment ◽  
Hospital Admissions ◽  
Partial Recovery ◽  
Phase 2 ◽  
Hospital Units ◽  
The World ◽  
Intensity Of Care ◽  
Almost All

Abstract At the end of 2019 a new Coronavirus appeared in China and, from there, it spread to the rest of the world. On 24th May, 2020, the confirmed cases in the world were more than 5 million and the deaths almost 350.000. At the end of May, Italy reported more than 27.000 cases among healthcare professionals and 163 deaths among physicians. The National Health Systems from almost all over the world, including Italy’s, were unprepared for this pandemic, and this generated important consequences of organizational nature. All elective and urgent specialized activities were completely reorganized, and many hospital units were partially or completely converted to the care of the COVID-19 patients. A significant reduction in hospital admissions for acute heart disease were recorded during the SARS-CoV-2 pandemic and, in order to gradually resume hospital activities, the Italian National Phase 2 Plan for the partial recovery of activities, must necessarily be associated with a Phase 2 Health Plan. In regards to the cardiac outpatient activities we need to identify short term goals, i.e. reschedule the suspended outpatient activities, revise the waiting lists, review the ‘timings’ of the bookings. This will reduce the number of available examinations compared to the pre-Covid-19 era. The GP’s collaboration could represent an important resource, a structured telephone follow-up plan is advisable with the nursing staff’s involvement. It is equally important to set medium-long term goals, the pandemic could be an appropriate moment for making a virtue of necessity. It is time to reason on prescriptive appropriateness, telemedicine implementation intended as integration to the traditional management. It is time to restructure the cardiological units related to the issue of structural adjustment to the needs for functional isolation. Moreover, the creation of ‘grey zones’ with multidisciplinary management according to the intensity of care levels seems to be necessary as well as the identification of Covid dedicated cardiologies. Finally, the pandemic could represent the opportunity for a permanent renovation of the cardiological and territorial medicine activities.

scholarly journals The Salmonella enterica Serotype Typhimurium lpf, bcf, stb, stc, std, and sth Fimbrial Operons Are Required for Intestinal Persistence in Mice

2005 ◽  
Vol 73 (6) ◽  
pp. 3358-3366 ◽  
Author(s):  
Eric H. Weening ◽  
Jared D. Barker ◽  
Marijke C. Laarakker ◽  
Andrea D. Humphries ◽  
Renée M. Tsolis ◽  
...  
Keyword(s):  
Food Chain ◽  
Salmonella Enterica ◽  
Fecal Samples ◽  
Cba Mice ◽  
Time Period ◽  
Human Infections ◽  
Intestinal Persistence ◽  
Infection Experiments

ABSTRACT Salmonella enterica serotype Typhimurium causes human infections that can frequently be traced back through the food chain to healthy livestock whose intestine is colonized by the pathogen. Little is known about the genes important for intestinal carriage of S. enterica serotype Typhimurium in vertebrate animals. Here we characterized the role of 10 fimbrial operons, agf, fim, lpf, pef, bcf, stb, stc, std, stf, and sth, using competitive infection experiments performed in genetically susceptible (BALB/c) and resistant (CBA) mice. Deletion of agfAB, fimAICDHF, lpfABCDE, pefABCDI, bcfABCDEFG, stbABCD, stcABCD, stdAB, stfACDEFG, or sthABCDE did not reduce the ability of S. enterica serotype Typhimurium to colonize the spleen and cecum of BALB/c mice 5 days after infection. Similarly, deletion of agfAB, fimAICDHF, pefABCDI, and stfACDEFG did not result in reduced recovery of S. enterica serotype Typhimurium from fecal samples collected from infected CBA mice over a 30-day time period. However, S. enterica serotype Typhimurium strains carrying deletions in lpfABCDE, bcfABCDEFG, stbABCD, stcABCD, stdAB, or sthABCDE were recovered at significantly reduced numbers from the feces of CBA mice. There was a good correlation (R 2 = 0.9626) between competitive indices in the cecum and fecal samples of CBA mice at 30 days after infection, suggesting that the recovery of S. enterica serotype Typhimurium from fecal samples closely reflected its ability to colonize the cecum. Collectively, these data show that six fimbrial operons (lpf, bcf, stb, stc, std, and sth) contribute to long-term intestinal carriage of S. enterica serotype Typhimurium in genetically resistant mice.

scholarly journals Dietary mannose supplementation in phosphomannomutase 2 deficiency (PMM2-CDG)

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Roman Taday ◽  
Marianne Grüneberg ◽  
Ingrid DuChesne ◽  
Janine Reunert ◽  
Thorsten Marquardt
Keyword(s):  
Biological Effects ◽  
Randomized Study ◽  
Protein Glycosylation ◽  
Therapeutic Approaches ◽  
Double Blind ◽  
Time Period ◽  
Mean Time

Abstract Background PMM2-CDG (CDG-Ia) is the most frequent N-glycosylation disorder. While supplying mannose to PMM2-deficient fibroblasts corrects the altered N-glycosylation in vitro, short term therapeutic approaches with mannose supplementation in PMM2-CDG patients have been unsuccessful. Mannose found no further mention in the design of a potential therapy for PMM2-CDG in the past years, as it applies to be ineffective. This retrospective study analyzes the first long term mannose supplementation in 20 PMM2-CDG patients. Mannose was given at a total of 1–2 g mannose/kg b.w./d divided into 5 single doses over a mean time of 57,75 ± 25,85 months. Protein glycosylation, blood mannose concentration and clinical presentation were monitored in everyday clinical practice. Results After a mean time period of more than 1 year the majority of patients showed significant improvements in protein glycosylation. Conclusion Dietary mannose supplementation shows biological effects in PMM2-CDG patients improving glycosylation in the majority of patients. A double-blind randomized study is needed to examine the role of mannose in the design of a therapy for children with PMM2-CDG in more detail.

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