Africa and the global carbon cycle

Directory of Open Access Journals (Sweden)

Denning A Scott

2007-03-01

Full Text Available Abstract The African continent has a large and growing role in the global carbon cycle, with potentially important climate change implications. However, the sparse observation network in and around the African continent means that Africa is one of the weakest links in our understanding of the global carbon cycle. Here, we combine data from regional and global inventories as well as forward and inverse model analyses to appraise what is known about Africa's continental-scale carbon dynamics. With low fossil emissions and productivity that largely compensates respiration, land conversion is Africa's primary net carbon release, much of it through burning of forests. Savanna fire emissions, though large, represent a short-term source that is offset by ensuing regrowth. While current data suggest a near zero decadal-scale carbon balance, interannual climate fluctuations (especially drought induce sizeable variability in net ecosystem productivity and savanna fire emissions such that Africa is a major source of interannual variability in global atmospheric CO2. Considering the continent's sizeable carbon stocks, their seemingly high vulnerability to anticipated climate and land use change, as well as growing populations and industrialization, Africa's carbon emissions and their interannual variability are likely to undergo substantial increases through the 21st century.

The role of urbanization in the global carbon cycle

Directory of Open Access Journals (Sweden)

Galina eChurkina

2016-01-01

Full Text Available Urban areas account for more than 70% of CO2 emissions from burning fossil fuels. Urban expansion in tropics is responsible for 5% of the annual emissions from land use change. Here I show that the effect of urbanization on the global carbon cycle extends beyond these emissions. I quantify the contribution of urbanization to the major carbon fluxes and pools globally and identify gaps crucial for predicting the evolution of the carbon cycle in the future. Urban residents currently control ~22 (12-40 % of the land carbon uptake (112 PgC/yr and ~24 (15-39 % of the carbon emissions (117 PgC/yr from land globally. Urbanization resulted in the creation of new carbon pools on land such as buildings (~6.7 PgC and landfills (~30 PgC. Together these pools store 1.6 (±0.3 % of the total vegetation and soil carbon pools globally. The creation and maintenance of these new pools has been associated with high emissions of CO2, which are currently better understood than the processes associated with the dynamics of these pools and accompanying uptake of carbon. Predictions of the future trajectories of the global carbon cycle will require a much better understanding of how urban development affects the carbon cycle over the long term.

Africa and the global carbon cycle

CSIR Research Space (South Africa)

Williams, CA

2007-03-01

Full Text Available The African continent has a large and growing role in the global carbon cycle, with potentially important climate change implications. However, the sparse observation network in and around the African continent means that Africa is one...

How Does Globalization Affect the Synchronization of Business Cycles?

OpenAIRE

Ayhan Kose; Eswar S Prasad; Marco Terrones

2003-01-01

This paper examines the impact of rising trade and financial integration on international business cycle comovement among a large group of industrial and developing countries. The results provide at best limited support for the conventional wisdom that globalization has increased the degree of synchronization of business cycles. The evidence that trade and financial integration enhance global spillovers of macroeconomic fluctuations is mostly limited to industrial countries. One striking resu...

Calcium fertilization increases the concentration of calcium in sapwood and calcium oxalate in foliage of red spruce

Science.gov (United States)

Kevin T. Smith; Walter C. Shortle; Jon H. Connolly; Rakesh Minocha; Jody Jellison

2009-01-01

Calcium cycling plays a key role in the health and productivity of red spruce forests in the northeastern US. A portion of the flowpath of calcium within forests includes translocation as Ca2+ in sapwood and accumulation as crystals of calcium oxalate in foliage. Concentrations of Ca in these tree tissues have been used as markers of...

Compression and rupture cycles as tools for compressibility characterization application to apatitic calcium phosphates

Energy Technology Data Exchange (ETDEWEB)

Pontier, C. [S.P.C.T.S., Faculte des Sciences, Limoges (France); G.E.F., Faculte de Pharmacie, Limoges (France); Viana, M.; Chulia, D. [G.E.F., Faculte de Pharmacie, Limoges (France); Champion, E.; Bernache-Assollant, D. [S.P.C.T.S., Faculte des Sciences, Limoges (France)

2002-07-01

Measurement of the cycles of compression and rupture helps to understand the phenomena occurring during compaction. Different parameters are deduced from the cycles, such as the packing of the material and energies used during compression. The ratio between the energy of rupture and the energy of compaction defines the efficacy of compaction of the materials. This technique is applied to ceramic materials using apatitic calcium phosphates with a Ca/P molar ratio of 1.5 (apatitic tricalcium phosphate and {beta}-tricalcium phosphate) and 1.667 (stoichiometric hydroxyapatite). The methodology uses a uniaxial instrumented press to plot the cycles of compaction and rupture. The results point out the good compaction and cohesion properties of apatitic tricalcium phosphate, compared to the other apatitic materials. (orig.)

Assessing Students' Disciplinary and Interdisciplinary Understanding of Global Carbon Cycling

Science.gov (United States)

You, Hye Sun; Marshall, Jill A.; Delgado, Cesar

2018-01-01

Global carbon cycling describes the movement of carbon through atmosphere, biosphere, geosphere, and hydrosphere; it lies at the heart of climate change and sustainability. To understand the global carbon cycle, students will require "interdisciplinary knowledge." While standards documents in science education have long promoted…

Changing global carbon cycle

International Nuclear Information System (INIS)

Canadell, Pep

2007-01-01

Full text: The increase in atmospheric carbon dioxide (C02) is the single largest human perturbation on the earth's radiative balance contributing to climate change. Its rate of change reflects the balance between anthropogenic carbon emissions and the dynamics of a number of terrestrial and ocean processes that remove or emit C02. It is the long term evolution of this balance that will determine to large extent the speed and magnitude of the human induced climate change and the mitigation requirements to stabilise atmospheric C02 concentrations at any given level. In this talk, we show new trends in global carbon sources and sinks, with particularly focus on major shifts occurring since 2000 when the growth rate of atmospheric C02 has reached its highest level on record. The acceleration in the C02 growth results from the combination of several changes in properties of the carbon cycle, including: acceleration of anthropogenic carbon emissions; increased carbon intensity of the global economy, and decreased efficiency of natural carbon sinks. We discuss in more detail some of the possible causes of the reduced efficiency of natural carbon sinks on land and oceans, such as the decreased net sink in the Southern Ocean and on terrestrial mid-latitudes due to world-wide occurrence of drought. All these changes reported here characterise a carbon cycle that is generating stronger than expected climate forcing, and sooner than expected

Business Cycle Volatility and Globalization: A Survey

OpenAIRE

Claudia M. Buch

2002-01-01

The globalization of capital and product markets has many implications for economic welfare. Countries can specialize in the production of goods for which they have comparative advantages, and capital is allocated more efficiently. However, one potentially adverse effect of globalization is the possibility that business cycle volatility might increase. Rapid and badly co-ordinated capital account liberalization has been blamed for enhancing the vulnerability of emerging markets to unstable in...

Satellite Global and Hemispheric Lower Tropospheric Temperature Annual Temperature Cycle

Directory of Open Access Journals (Sweden)

Michael A. Brunke

2010-11-01

Full Text Available Previous analyses of the Earth’s annual cycle and its trends have utilized surface temperature data sets. Here we introduce a new analysis of the global and hemispheric annual cycle using a satellite remote sensing derived data set during the period 1979–2009, as determined from the lower tropospheric (LT channel of the MSU satellite. While the surface annual cycle is tied directly to the heating and cooling of the land areas, the tropospheric annual cycle involves additionally the gain or loss of heat between the surface and atmosphere. The peak in the global tropospheric temperature in the 30 year period occurs on 10 July and the minimum on 9 February in response to the larger land mass in the Northern Hemisphere. The actual dates of the hemispheric maxima and minima are a complex function of many variables which can change from year to year thereby altering these dates.Here we examine the time of occurrence of the global and hemispheric maxima and minima lower tropospheric temperatures, the values of the annual maxima and minima, and the slopes and significance of the changes in these metrics.  The statistically significant trends are all relatively small. The values of the global annual maximum and minimum showed a small, but significant trend. Northern and Southern Hemisphere maxima and minima show a slight trend toward occurring later in the year. Most recent analyses of trends in the global annual cycle using observed surface data have indicated a trend toward earlier maxima and minima.

The observed sensitivity of the global hydrological cycle to changes in surface temperature

International Nuclear Information System (INIS)

Arkin, Phillip A; Janowiak, John; Smith, Thomas M; Sapiano, Mathew R P

2010-01-01

Climate models project large changes in global surface temperature in coming decades that are expected to be accompanied by significant changes in the global hydrological cycle. Validation of model simulations is essential to support their use in decision making, but observing the elements of the hydrological cycle is challenging, and model-independent global data sets exist only for precipitation. We compute the sensitivity of the global hydrological cycle to changes in surface temperature using available global precipitation data sets and compare the results against the sensitivities derived from model simulations of 20th century climate. The implications of the results for the global climate observing system are discussed.

Watch: Current knowledge of the terrestrial Global Water Cycle"

NARCIS (Netherlands)

Harding, R.; Best, M.; Hagemann, S.; Kabat, P.; Tallaksen, L.M.; Warnaars, T.; Wiberg, D.; Weedon, G.P.; Lanen, van H.A.J.; Ludwig, F.; Haddeland, I.

2011-01-01

Water-related impacts are among the most important consequences of increasing greenhouse gas concentrations. Changes in the global water cycle will also impact the carbon and nutrient cycles and vegetation patterns. There is already some evidence of increasing severity of floods and droughts and

Drought and Carbon Cycling of Grassland Ecosystems under Global Change: A Review

Directory of Open Access Journals (Sweden)

Tianjie Lei

2016-10-01

Full Text Available In recent years, the increased intensity and duration of droughts have dramatically altered the structure and function of grassland ecosystems, which have been forced to adapt to this change in climate. Combinations of global change drivers such as elevated atmospheric CO2 concentration, warming, nitrogen (N deposition, grazing, and land-use change have influenced the impact that droughts have on grassland C cycling. This influence, to some extent, can modify the relationship between droughts and grassland carbon (C cycling in the multi-factor world. Unfortunately, prior reviews have been primarily anecdotal from the 1930s to the 2010s. We investigated the current state of the study on the interactive impacts of multiple factors under drought scenarios in grassland C cycling and provided scientific advice for dealing with droughts and managing grassland C cycling in a multi-factor world. Currently, adequate information is not available on the interaction between droughts and global change drivers, which would advance our understanding of grassland C cycling responses. It was determined that future experiments and models should specifically test how droughts regulate grassland C cycling under global changes. Previous multi-factor experiments of current and future global change conditions have studied various drought scenarios poorly, including changes in precipitation frequency and amplitude, timing, and interactions with other global change drivers. Multi-factor experiments have contributed to quantifying these potential changes and have provided important information on how water affects ecosystem processes under global change. There is an urgent need to establish a systematic framework that can assess ecosystem dynamic responses to droughts under current and future global change and human activity, with a focus on the combined effects of droughts, global change drivers, and the corresponding hierarchical responses of an ecosystem.

Weak ionization of the global ionosphere in solar cycle 24

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Y. Q. Hao

2014-07-01

Full Text Available Following prolonged and extremely quiet solar activity from 2008 to 2009, the 24th solar cycle started slowly. It has been almost 5 years since then. The measurement of ionospheric critical frequency (foF2 shows the fact that solar activity has been significantly lower in the first half of cycle 24, compared to the average levels of cycles 19 to 23; the data of global average total electron content (TEC confirm that the global ionosphere around the cycle 24 peak is much more weakly ionized, in contrast to cycle 23. The weak ionization has been more notable since the year 2012, when both the ionosphere and solar activity were expected to be approaching their maximum level. The undersupply of solar extreme ultraviolet (EUV irradiance somewhat continues after the 2008–2009 minimum, and is considered to be the main cause of the weak ionization. It further implies that the thermosphere and ionosphere in the first solar cycle of this millennium would probably differ from what we have learned from the previous cycles of the space age.

Advances In Understanding Global Water Cycle With Advent of GPM Mission

Science.gov (United States)

Smith, Eric A.

2002-01-01

During the coming decade, the internationally organized Global Precipitation Measurement (GPM) Mission will take an important step in creating a global precipitation observing system from space based on an international fleet of satellites operated as a constellation. One perspective for understanding the nature of GPM is that it will be a hierarchical system of datastreams beginning with very high caliber combined dual frequency radar/passive microwave (PMW) rain-radiometer retrievals, to high caliber PMW rain-radiometer only retrievals, and then on to blends of the former datastreams with additional lower-caliber PMW-based and IR-based rain retrievals. Within the context of the now emerging global water & energy cycle (GWEC) programs of a number of research agencies throughout the world, GPM serves as a centerpiece space mission for improving our understanding of the Earth's water cycle from a global measurement perspective and on down to regional scales and below. One of the salient problems within our current understanding of the global water and energy cycle is determining whether a change in the rate of the water cycle is accompanying changes in climate, e.g., climate warming. As there are a number of ways in which to define a rate-change of the global water cycle, it is not entirely clear as to what constitutes such a determination. This paper first presents an overview of the GPM Mission and how its overriding scientific objectives for climate, weather, and hydrology flow from the anticipated improvements that are being planned for the constellation-based measuring system. Next, the paper shows how the GPM observations can be used within the framework of the oceanic and continental water budget equations to determine whether a given perturbation in precipitation is indicative of an actual rate change in the water cycle, consistent with required responses in water storage and/or water flux transport processes, or whether it is simply part of the natural

GLOBALIZATION VERSUS SEGREGATION - BUSINESS CYCLES SYNCHRONIZATION IN EUROPE

Directory of Open Access Journals (Sweden)

Sebastian Florian Enea

2012-12-01

Full Text Available Globalization and business cycles are equally elusive economic phenomena; hence they represent a continuous research possibility and a source of possible inquiries due to their complex nature. The aim of the paper is to explain the synchronization of business cycles using the relationship between the growth rate of the GDP and FDI, considered as percentage of the GDP. The results show that there is no unique European business cycle, but two cores between which countries migrate and stress out the importance of the FDI channel in business cycle transmission. The future research directions will employ fuzzy cluster techniques, used on a larger sample.

A probabilistic assessment of calcium carbonate export and dissolution in the modern ocean

OpenAIRE

Battaglia Gianna; Steinacher Marco; Joos Fortunat

2016-01-01

The marine cycle of calcium carbonate (CaCO3) is an important element of the carbon cycle and co-governs the distribution of carbon and alkalinity within the ocean. However, CaCO3 export fluxes and mechanisms governing CaCO3 dissolution are highly uncertain. We present an observationally constrained, probabilistic assessment of the global and regional CaCO3 budgets. Parameters governing pelagic CaCO3 export fluxes and dissolution rates are sampled using a Monte Carlo sche...

INTRODUCTION: Anticipated changes in the global atmospheric water cycle

Science.gov (United States)

Allan, Richard P.; Liepert, Beate G.

2010-06-01

The atmospheric branch of the water cycle, although containing just a tiny fraction of the Earth's total water reserves, presents a crucial interface between the physical climate (such as large-scale rainfall patterns) and the ecosystems upon which human societies ultimately depend. Because of the central importance of water in the Earth system, the question of how the water cycle is changing, and how it may alter in future as a result of anthropogenic changes, present one of the greatest challenges of this century. The recent Intergovernmental Panel on Climate Change report on Climate Change and Water (Bates et al 2008) highlighted the increasingly strong evidence of change in the global water cycle and associated environmental consequences. It is of critical importance to climate prediction and adaptation strategies that key processes in the atmospheric water cycle are precisely understood and determined, from evaporation at the surface of the ocean, transport by the atmosphere, condensation as cloud and eventual precipitation, and run-off through rivers following interaction with the land surface, sub-surface, ice, snow and vegetation. The purpose of this special focus issue of Environmental Research Letters on anticipated changes in the global atmospheric water cycle is to consolidate the recent substantial advances in understanding past, present and future changes in the global water cycle through evidence built upon theoretical understanding, backed up by observations and borne out by climate model simulations. Thermodynamic rises in water vapour provide a central constraint, as discussed in a guest editorial by Bengtsson (2010). Theoretical implications of the Clausius-Clapeyron equation are presented by O'Gorman and Muller (2010) and with reference to a simple model (Sherwood 2010) while observed humidity changes confirm these anticipated responses at the land and ocean surface (Willett et al 2008). Rises in low-level moisture are thought to fuel an

Global Water Cycle Diagrams Minimize Human Influence and Over-represent Water Security

Science.gov (United States)

Abbott, B. W.; Bishop, K.; Zarnetske, J. P.; Minaudo, C.; Chapin, F. S., III; Plont, S.; Marçais, J.; Ellison, D.; Roy Chowdhury, S.; Kolbe, T.; Ursache, O.; Hampton, T. B.; GU, S.; Chapin, M.; Krause, S.; Henderson, K. D.; Hannah, D. M.; Pinay, G.

2017-12-01

The diagram of the global water cycle is the central icon of hydrology, and for many people, the point of entry to thinking about key scientific concepts such as conservation of mass, teleconnections, and human dependence on ecological systems. Because humans now dominate critical components of the hydrosphere, improving our understanding of the global water cycle has graduated from an academic exercise to an urgent priority. To assess how the water cycle is conceptualized by researchers and the general public, we analyzed 455 water cycle diagrams from textbooks, scientific articles, and online image searches performed in different languages. Only 15% of diagrams integrated human activity into the water cycle and 77% showed no sign of humans whatsoever, although representation of humans varied substantially by region (lowest in China, N. America, and Australia; highest in Western Europe). The abundance and accessibility of freshwater resources were overrepresented, with 98% of diagrams omitting water pollution and climate change, and over 90% of diagrams making no distinction for saline groundwater and lakes. Oceanic aspects of the water cycle (i.e. ocean size, circulation, and precipitation) and related teleconnections were nearly always underrepresented. These patterns held across disciplinary boundaries and through time. We explore the historical and contemporary reasons for some of these biases and present a revised version of the global water cycle based on research from natural and social sciences. We conclude that current depictions of the global water cycle convey a false sense of water security and that reintegrating humans into water cycle diagrams is an important first step towards understanding and sustaining the hydrosocial cycle.

The effect of calcium and vitamin D supplementation on menstrual cycle, body mass index and hyperandrogenism state of women with poly cystic ovarian syndrome

Directory of Open Access Journals (Sweden)

Hatav Ghasemi Tehrani

2014-01-01

Full Text Available Background: Poly cystic ovary syndrome (PCOS is considered one of the most common endocrine disorders of women in reproductive age. The aim of this study was evaluating the efficacy of calcium and Vitamin D supplementation on the regularity of menstrual cycles, body mass index (BMI and hyper androgenism state of women with PCOS. Materials and Methods: In this clinical trial, 80 women with PCOS were evaluated. They randomly located in four groups receiving metformin (group 1, metformin plus calcium and Vitamin D (group 2, calcium and Vitamin D (group 3 and placebo (group 4 for 4 months. BMI, regularity of menstrual cycles, hyperandrogenism (hirsutism and acne and serum calcium and Vitamin D levels were compared in four studying groups at baseline and 4 months after the trial. Results: All studied subjects were similar at baseline (P > 0.05. After trial, the frequency of hirsutism and acne were not different among groups. Frequency regular menstrual cycle and dominant follicle were significantly higher in group 1 and 2 than others (P < 0.05. After trial, there was no significant difference with respect to BMI among groups. Conclusion: Vitamin D and calcium supplementation in addition to metformin therapy in women with PCOS could result in a better outcome in a variety of PCOS symptoms including menstrual regularity, and ovulation.

Salinity Remote Sensing and the Study of the Global Water Cycle

Science.gov (United States)

Lagerloef, G. S. E.; LeVine, David M.; Chao, Y.; Colomb, F. Raul; Font, J.

2007-01-01

The SMOS and AquariusISAC-D satellite missions will begin a new era to map the global sea surface salinity (SSS) field and its variability from space within the next twothree years. They will provide critical data needed to study the interactions between the ocean circulation, global water cycle and climate. Key scientific issues to address are (1) mapping large expanses of the ocean where conventional SSS data do not yet exist, (2) understanding the seasonal and interannual SSS variations and the link to precipitation, evaporation and sea-ice patterns, (3) links between SSS and variations in the oceanic overturning circulation, (4) air-sea coupling processes in the tropics that influence El Nino, and (4) closing the marine freshwater budget. There is a growing body of oceanographic evidence in the form of salinity trends that portend significant changes in the hydrologic cycle. Over the past several decades, highlatitude oceans have become fresher while the subtropical oceans have become saltier. This change is slowly spreading into the subsurface ocean layers and may be affecting the strength of the ocean's therrnohaline overturning circulation. Salinity is directly linked to the ocean dynamics through the density distribution, and provides an important signature of the global water cycle. The distribution and variation of oceanic salinity is therefore attracting increasing scientific attention due to the relationship to the global water cycle and its influence on circulation, mixing, and climate processes. The oceans dominate the water cycle by providing 86% of global surface evaporation (E) and receiving 78% of global precipitation (P). Regional differences in E-P, land runoff, and the melting or freezing of ice affect the salinity of surface water. Direct observations of E-P over the ocean have large uncertainty, with discrepancies between the various state-of-the-art precipitation analyses of a factor of two or more in many regions. Quantifying the climatic

GEWEX: The Global Energy and Water Cycle Experiment

Science.gov (United States)

Chahine, M.; Vane, D.

1994-01-01

GEWEX is one of the world's largest global change research programs. Its purpose is to observe and understand the hydrological cycle and energy fluxes in the atmosphere, at land surfaces and in the upper oceans.

Modern Estimates of Global Water Cycle Fluxes

Science.gov (United States)

Rodell, M.; Beaudoing, H. K.; L'Ecuyer, T. S.; Olson, W. S.

2014-12-01

The goal of the first phase of the NASA Energy and Water Cycle Study (NEWS) Water and Energy Cycle Climatology project was to develop "state of the global water cycle" and "state of the global energy cycle" assessments based on data from modern ground and space based observing systems and data integrating models. Here we describe results of the water cycle assessment, including mean annual and monthly fluxes over continents and ocean basins during the first decade of the millennium. To the extent possible, the water flux estimates are based on (1) satellite measurements and (2) data-integrating models. A careful accounting of uncertainty in each flux was applied within a routine that enforced multiple water and energy budget constraints simultaneously in a variational framework, in order to produce objectively-determined, optimized estimates. Simultaneous closure of the water and energy budgets caused the ocean evaporation and precipitation terms to increase by about 10% and 5% relative to the original estimates, mainly because the energy budget required turbulent heat fluxes to be substantially larger in order to balance net radiation. In the majority of cases, the observed annual, surface and atmospheric water budgets over the continents and oceans close with much less than 10% residual. Observed residuals and optimized uncertainty estimates are considerably larger for monthly surface and atmospheric water budget closure, often nearing or exceeding 20% in North America, Eurasia, Australia and neighboring islands, and the Arctic and South Atlantic Oceans. The residuals in South America and Africa tend to be smaller, possibly because cold land processes are a non-issue. Fluxes are poorly observed over the Arctic Ocean, certain seas, Antarctica, and the Australasian and Indonesian Islands, leading to reliance on atmospheric analysis estimates. Other details of the study and future directions will be discussed.

Climate Change and Expected Impacts on the Global Water Cycle

Science.gov (United States)

Rind, David; Hansen, James E. (Technical Monitor)

2002-01-01

How the elements of the global hydrologic cycle may respond to climate change is reviewed, first from a discussion of the physical sensitivity of these elements to changes in temperature, and then from a comparison of observations of hydrologic changes over the past 100 million years. Observations of current changes in the hydrologic cycle are then compared with projected future changes given the prospect of global warming. It is shown that some of the projections come close to matching the estimated hydrologic changes that occurred long ago when the earth was very warm.

Global Energy and Water Cycle Experiment (GEWEX) and the Continental-scale International Project (GCIP)

Science.gov (United States)

Vane, Deborah

1993-01-01

A discussion of the objectives of the Global Energy and Water Cycle Experiment (GEWEX) and the Continental-scale International Project (GCIP) is presented in vugraph form. The objectives of GEWEX are as follows: determine the hydrological cycle by global measurements; model the global hydrological cycle; improve observations and data assimilation; and predict response to environmental change. The objectives of GCIP are as follows: determine the time/space variability of the hydrological cycle over a continental-scale region; develop macro-scale hydrologic models that are coupled to atmospheric models; develop information retrieval schemes; and support regional climate change impact assessment.

Can we Observe and Assess Whether the Global Hydrological Cycle is "Intensifying"?

Science.gov (United States)

Wood, E. F.; Sheffield, J.

2012-12-01

There is controversy over whether the hydrological cycle is "intensifying" (or "accelerating"), and if so how and where? Resolving this critical question is a central goal of both national (e.g. NASA's Energy and Water cycle Study: NEWS) and international (WCRP Global Energy and Water cycle Experiment: GEWEX) programs. Its resolution has significant implications for understanding changes in hydroclimatic states and variability, and in future water security at regional to global scales. Over the last decade a number of papers have addressed trends and change in specific water cycle variables with results that can best be described as inconclusive, regardless of the conclusions of specific papers. In this presentation a number of recent studies will be reviewed for their consistency in assessing whether collectively one can make conclusions regarding how the hydrologic cycle is changing. The presentation will also demonstrate a pathway for analyzing where to observe for the detection of change based on a NASA-supported, global, 1983-2009, terrestrial water cycle Earth System Data Record project being led by the author. Initial results will be presented and a discussion presented on the extent that the proposed strategy can be used to detect change in the terrestrial hydrological cycle.

Increasing water cycle extremes in California and in relation to ENSO cycle under global warming

Science.gov (United States)

Yoon, Jin-Ho; Wang, S-Y Simon; Gillies, Robert R.; Kravitz, Ben; Hipps, Lawrence; Rasch, Philip J.

2015-01-01

Since the winter of 2013–2014, California has experienced its most severe drought in recorded history, causing statewide water stress, severe economic loss and an extraordinary increase in wildfires. Identifying the effects of global warming on regional water cycle extremes, such as the ongoing drought in California, remains a challenge. Here we analyse large-ensemble and multi-model simulations that project the future of water cycle extremes in California as well as to understand those associations that pertain to changing climate oscillations under global warming. Both intense drought and excessive flooding are projected to increase by at least 50% towards the end of the twenty-first century; this projected increase in water cycle extremes is associated with a strengthened relation to El Niño and the Southern Oscillation (ENSO)—in particular, extreme El Niño and La Niña events that modulate California's climate not only through its warm and cold phases but also its precursor patterns. PMID:26487088

Terrestrial nitrogen-carbon cycle interactions at the global scale.

Science.gov (United States)

Zaehle, S

2013-07-05

Interactions between the terrestrial nitrogen (N) and carbon (C) cycles shape the response of ecosystems to global change. However, the global distribution of nitrogen availability and its importance in global biogeochemistry and biogeochemical interactions with the climate system remain uncertain. Based on projections of a terrestrial biosphere model scaling ecological understanding of nitrogen-carbon cycle interactions to global scales, anthropogenic nitrogen additions since 1860 are estimated to have enriched the terrestrial biosphere by 1.3 Pg N, supporting the sequestration of 11.2 Pg C. Over the same time period, CO2 fertilization has increased terrestrial carbon storage by 134.0 Pg C, increasing the terrestrial nitrogen stock by 1.2 Pg N. In 2001-2010, terrestrial ecosystems sequestered an estimated total of 27 Tg N yr(-1) (1.9 Pg C yr(-1)), of which 10 Tg N yr(-1) (0.2 Pg C yr(-1)) are due to anthropogenic nitrogen deposition. Nitrogen availability already limits terrestrial carbon sequestration in the boreal and temperate zone, and will constrain future carbon sequestration in response to CO2 fertilization (regionally by up to 70% compared with an estimate without considering nitrogen-carbon interactions). This reduced terrestrial carbon uptake will probably dominate the role of the terrestrial nitrogen cycle in the climate system, as it accelerates the accumulation of anthropogenic CO2 in the atmosphere. However, increases of N2O emissions owing to anthropogenic nitrogen and climate change (at a rate of approx. 0.5 Tg N yr(-1) per 1°C degree climate warming) will add an important long-term climate forcing.

Calcium microdomains near R-type calcium channels control the induction of presynaptic LTP at parallel fiber to Purkinje cell synapses

Science.gov (United States)

Myoga, Michael H.; Regehr, Wade G.

2011-01-01

R-type calcium channels in postsynaptic spines signal through functional calcium microdomains to regulate a calcium-calmodulin sensitive potassium channel that in turn regulates postsynaptic hippocampal LTP. Here we ask whether R-type calcium channels in presynaptic terminals also signal through calcium microdomains to control presynaptic LTP. We focus on presynaptic LTP at parallel fiber to Purkinje cell synapses in the cerebellum (PF-LTP), which is mediated by calcium/calmodulin-stimulated adenylyl cyclases. Although most presynaptic calcium influx is through N-type and P/Q-type calcium channels, blocking these channels does not disrupt PF-LTP, but blocking R-type calcium channels does. Moreover, global calcium signaling cannot account for the calcium dependence of PF-LTP because R-type channels contribute modestly to overall calcium entry. These findings indicate that within presynaptic terminals, R-type calcium channels produce calcium microdomains that evoke presynaptic LTP at moderate frequencies that do not greatly increase global calcium levels,. PMID:21471358

Effects of Seawater Acidification on the Liffe Cycle and Fitness of Opossum Shrimp Population

Science.gov (United States)

Much of the current concern about ecological effects of ocean acidification focuses on molluscs and coccolithophores because of their importance in the global calcium cycle. However, many other marine organisms are likely to be affected by acidification because of their known se...

Effects of Seawater Acidification on the Life Cycle and fitness of Opossum Shrimp Populations

Science.gov (United States)

Much of the current concern about ecological effects of ocean acidification focuses on molluscs and coccolithophores because of their importance in the global calcium cycle. However, many other marine organisms are likely to be affected by acidification because of their known ph...

Carbonate-silicate cycle models of the long-term carbon cycle, carbonate accumulation in the oceans, and climate

International Nuclear Information System (INIS)

Caldeira, K.G.

1991-01-01

Several models of the long-term carbon cycle, incorporating models of the carbonate-silicate cycle, were developed and utilized to investigate issues relating to global climate and the causes and consequences of changes in calcium carbonate accumulation in the oceans. Model results indicate that the marked mid-Cretaceous (120 Ma) global warming could be explained by increased rates of release of carbon dioxide from subduction-zone metamorphism and mid-ocean-ridges, in conjunction with paleogeographic factors. Since the mid-Cretaceous, the primary setting for calcium carbonate accumulation in the oceans has shifted from shallow-water to deep-water environments. Model results suggest that this shift could have major consequences for the carbonate-silicate cycle and climate, and lead to significant increases in the flux of metamorphic carbon dioxide to the atmosphere. Increases in pelagic carbonate productivity, and decreases in tropical shallow-water area available for neritic carbonate accumulation, have both been proposed as the primary cause of this shift. Two lines of evidence developed here (one involving a statistical analysis of Tertiary carbonate-accumulation and oxygen-isotope data, and another based on modeling the carbonate-silicate cycle and ocean chemistry) suggest that a decrease in tropical shallow-water area was more important than increased pelagic productivity in explaining this shift. Model investigations of changes in ocean chemistry at the Cretaceous/Tertiary (K/T) boundary (66 Ma) indicate that variations in deep-water carbonate productivity may affect shallow-water carbonate accumulation rates through a mechanism involving surface-water carbonate-ion concentration. In the aftermath of the K/T boundary event, deep-water carbonate production and accumulation were significantly reduced as a result of the extinction of calcareous plankton

Global dietary calcium intake among adults: a systematic review

Science.gov (United States)

Purpose: Low calcium intake may adversely affect bone health in adults. Recognizing the presence of low calcium intake is necessary to develop national strategies to optimize intake. To highlight regions where calcium intake should be improved, we systematically searched for the most representative ...

Comparing the Life Cycle Energy Consumption, Global ...

Science.gov (United States)

Managing the water-energy-nutrient nexus for the built environment requires, in part, a full system analysis of energy consumption, global warming and eutrophication potentials of municipal water services. As an example, we evaluated the life cycle energy use, greenhouse gas (GHG) emissions and aqueous nutrient releases of the whole anthropogenic municipal water cycle starting from raw water extraction to wastewater treatment and reuse/discharge for five municipal water and wastewater systems. The assessed options included conventional centralized services and four alternative options following the principles of source-separation and water fit-for-purpose. The comparative life cycle assessment identified that centralized drinking water supply coupled with blackwater energy recovery and on-site greywater treatment and reuse was the most energyand carbon-efficient water service system evaluated, while the conventional (drinking water and sewerage) centralized system ranked as the most energy- and carbon-intensive system. The electricity generated from blackwater and food residuals co-digestion was estimated to offset at least 40% of life cycle energy consumption for water/waste services. The dry composting toilet option demonstrated the lowest life cycle eutrophication potential. The nutrients in wastewater effluent are the dominating contributors for the eutrophication potential for the assessed system configurations. Among the parameters for which variability

Intensified Vegetation Water Use due to Soil Calcium Leaching under Acid Deposition

Science.gov (United States)

Lanning, M.; Wang, L.; Scanlon, T. M.; Vadeboncoeur, M. A.; Adams, M. B.; Epstein, H. E.; Druckenbrod, D.

2017-12-01

Despite the important role vegetation plays in the global water cycle, the exact controls of vegetation water use, especially the role of soil biogeochemistry, remain elusive. Nitrate and sulfate deposition from fossil fuel burning has caused significant soil acidification, leading to the leaching of soil base cations. From a physiological perspective, plants require various soil cations as signaling and regulatory ions as well as integral parts of structural molecules; a depletion of soil cations can cause reduced productivity and abnormal responses to environmental change. A deficiency in calcium could also potentially prolong stomatal opening, leading to increased transpiration until enough calcium had been acquired to stimulate stomatal closure. Based on the plant physiology and the nature of acidic deposition, we hypothesize that depletion of the soil calcium supply, induced by acid deposition, would intensify vegetation water use at the watershed scale. We tested this hypothesis by analyzing a long-term and unique data set (1989-2012) of soil lysimeter data along with stream flow and evapotranspiration data at the Fernow Experimental Forest. We show that depletion of soil calcium by acid deposition can intensify vegetation water use ( 10% increase in evapotranspiration and depletion in soil water) for the first time. These results are critical to understanding future water availability, biogeochemical cycles, and surficial energy flux and may help reduce uncertainties in terrestrial biosphere models.

Has globalization increased the synchronicity of international business cycles?

OpenAIRE

Berge, Travis

2012-01-01

The past 30 years have been witness to an inexorable change in the degree to which economies are connected internationally. At the same time, the 2007-2008 recession was the first ‘global recession’ in decades. This article explores how international trade and cross-border holdings financial assets impact the synchronization of business cycles internationally. The paper begins by producing chronologies of business cycle turning points for a group of 32 major economies covering 40 years of his...

Calcium waves.

Science.gov (United States)

Jaffe, Lionel F

2008-04-12

Waves through living systems are best characterized by their speeds at 20 degrees C. These speeds vary from those of calcium action potentials to those of ultraslow ones which move at 1-10 and/or 10-20 nm s(-1). All such waves are known or inferred to be calcium waves. The two classes of calcium waves which include ones with important morphogenetic effects are slow waves that move at 0.2-2 microm s(-1) and ultraslow ones. Both may be propagated by cycles in which the entry of calcium through the plasma membrane induces subsurface contraction. This contraction opens nearby stretch-sensitive calcium channels. Calcium entry through these channels propagates the calcium wave. Many slow waves are seen as waves of indentation. Some are considered to act via cellular peristalsis; for example, those which seem to drive the germ plasm to the vegetal pole of the Xenopus egg. Other good examples of morphogenetic slow waves are ones through fertilizing maize eggs, through developing barnacle eggs and through axolotl embryos during neural induction. Good examples of ultraslow morphogenetic waves are ones during inversion in developing Volvox embryos and across developing Drosophila eye discs. Morphogenetic waves may be best pursued by imaging their calcium with aequorins.

Investigation of duty cycle effect on corrosion properties of electrodeposited calcium phosphate coatings

Energy Technology Data Exchange (ETDEWEB)

Azem, Funda Ak, E-mail: funda.ak@deu.edu.tr [Dokuz Eylul University, Faculty of Engineering, Department of Metallurgical and Materials Engineering, Buca, 35390 Izmir (Turkey); Delice, Tulay Koc, E-mail: tulaykocdelice@gmail.com [Dokuz Eylul University, The Graduate School of Natural and Applied Sciences, Buca, 35390 Izmir (Turkey); Ungan, Guler, E-mail: gulerungan@hotmail.com [Es Group, Izmir (Turkey); Cakir, Ahmet, E-mail: ahmet.cakir@deu.edu.tr [Dokuz Eylul University, Faculty of Engineering, Department of Metallurgical and Materials Engineering, Buca, 35390 Izmir (Turkey)

2016-11-01

The bioceramic calcium phosphate (CaP) is frequently used for improving bone fixation in titanium medical implants and thus increasing lifetime of the implant. It is known that the application of CaP coatings on metallic implant devices offers the possibility of combining the strength of the metals and the bioactivity of the ceramic materials. Many different techniques are available for producing CaP coatings. Electrochemical deposition method is widely used because of its ease of operation parameters, low temperature requirement, reproducibility and suitability for coating complex structures. This technique allows obtaining CaP coatings which promote bone in growth during the first healing period leading to permanent fixation. Electrochemical pulse technique is an alternative to calcium phosphate deposition techniques usually employed to cover orthopedic or dental titanium implant surfaces. Additionally, pulse electrodeposition technique can produce more uniform and denser CaP coatings on metallic implants. In this study, CaP based coatings were produced by electrochemical pulse technique on Ti6Al4V substrates. The resulting CaP deposits were investigated by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Corrosion properties of the CaP coatings were also investigated. The results showed that various duty cycle ranges have remarkably effect on morphology, crystallinity and corrosion properties of the produced CaP coatings. - Highlights: • Electrodeposited CaP based coating were produced by pulse deposition technique. • The pulsed electrodeposited coatings produced under 30% and 50% duty cycles were exhibited better corrosion resistance. • Produced coatings consist of irregular flake-like structure and compact network with fine needles.

Modeling of the Global Water Cycle - Analytical Models

Science.gov (United States)

Yongqiang Liu; Roni Avissar

2005-01-01

Both numerical and analytical models of coupled atmosphere and its underlying ground components (land, ocean, ice) are useful tools for modeling the global and regional water cycle. Unlike complex three-dimensional climate models, which need very large computing resources and involve a large number of complicated interactions often difficult to interpret, analytical...

Constraining the cause of the end-Guadalupian extinction with coupled records of carbon and calcium isotopes

Science.gov (United States)

Jost, A. B.; Mundil, R.; He, B.; Brown, S. T.; Altiner, D.; Sun, Y.; DePaolo, D. J.; Payne, J.

2013-12-01

A negative δ13C excursion in carbonate sediments from Guadalupian (Middle Permian) and Lopingian (Late Permian) stratigraphic sections has been interpreted to result from a large carbon cycle disturbance during end-Guadalupian extinction event (ca. 260 Ma). However, the carbon isotope data alone are insufficient to uniquely determine the type and magnitude of perturbations to the global carbon cycle. The carbon and calcium cycles are coupled via CaCO3 burial, so changes in calcium isotopes can be used to constrain the cause of a carbon isotope excursion. In this study, we present coupled carbon and calcium isotope records from three Guadalupian-Lopingian (G/L) sections in China and Turkey. Isotope records among our studied sections are inconsistent in both their δ13C and δ44/40Ca records. Similar inconsistencies in δ13C among sections occur across previously published datasets. Sections with large (>3‰) changes in δ13C either show evidence for diagenetic alteration or do not show δ13C and δ44/40Ca changes consistent with severe volcanic degassing from Emeishan or methane clathrate destabilization. We conclude that the large isotopic changes are more likely the result of local burial conditions or diagenetic effects, rather than a large carbon cycle disturbance. Perturbations to the global carbon and calcium cycles appear to have been much smaller across the G/L transition than across the subsequent Permian-Triassic boundary. This finding is consistent with recent paleobiological data showing that the end-Guadalupian extinction was much less severe than previously believed, and was indistinguishable in magnitude from background intervals. However, selective extinction of marine animals with passive respiratory physiology indicates that the G/L extinction cannot simply be due to background extinction or sampling failure, and that it was triggered by some environmental event. Therefore, any environmental event must have been small enough to not generate large

The impact of the presence on global markets of calcium carbide originating from China on other industry role players: the case of sa calcium carbide (PTY LTD

Directory of Open Access Journals (Sweden)

Royce Sitshonile Mazo

2017-12-01

Full Text Available This research assesses how the presence of calcium carbide originating from China has impacted on the operations of other role players in the industry. SA Calcium Carbide (Pty Ltd. located in Newcastle, South Africa, was used as a case study. The study spanned all markets where the company has a footprint meaning domestically, regionally and internationally. The aim of the study was to discern the extent to which companies like SA Calcium Carbide have been affected by the presence of products from China on the global market with special focus being put on the competitiveness in terms of pricing of products. The study used a survey strategy, and was exploratory in nature. The choice of the survey strategy was motivated by the need to collect both quantitative and qualitative data in order to meet the research objectives. The data was gathered, with an 80 percent response rate, using a questionnaire method from more than 70 current SA Calcium Carbide customers both from the domestic and the export side of the business. In order to consider the different perspectives of the whole scenario, 10 companies involved in either manufacturing or trading of Chinese manufactured calcium carbide were interviewed, some face to face and some telephonically. The study revealed that current customers, who are predominantly from the African continent, buy product from SA Calcium Carbide primarily because of its high quality. It also evident from the results that the export volumes of SA Calcium Carbide were on a gradual downward trend due to loss of market share to Chinese companies

Nitrogen attenuation of terrestrial carbon cycle response to global environmental factors

Science.gov (United States)

Atul Jain; Xiaojuan Yang; Haroon Kheshgi; A. David McGuire; Wilfred Post; David. Kicklighter

2009-01-01

Nitrogen cycle dynamics have the capacity to attenuate the magnitude of global terrestrial carbon sinks and sources driven by CO2 fertilization and changes in climate. In this study, two versions of the terrestrial carbon and nitrogen cycle components of the Integrated Science Assessment Model (ISAM) are used to evaluate how variation in nitrogen...

Interactions of C, N, P and S biogeochemical cycles and global change

International Nuclear Information System (INIS)

Wollast, R.; Mackenzie, F.T.

1993-01-01

The biochemical cycles of carbon, nitrogen, phosphorus and sulfur are tied to each other through biological productivity and to problems of global environmental change. Both natural changes in the cycles of the elements and interference and distortion of these cycles by human activities (e.g. disturbancies by agricultural, industrial and urbanization activities) will have impacts on ecosystems and human society. (UT)

Global LC/MS Metabolomics Profiling of Calcium Stressed and Immunosuppressant Drug Treated Saccharomyces cerevisiae

Directory of Open Access Journals (Sweden)

Stefan Jenkins

2013-12-01

Full Text Available Previous studies have shown that calcium stressed Saccharomyces cerevisiae, challenged with immunosuppressant drugs FK506 and Cyclosporin A, responds with comprehensive gene expression changes and attenuation of the generalized calcium stress response. Here, we describe a global metabolomics workflow for investigating the utility of tracking corresponding phenotypic changes. This was achieved by efficiently analyzing relative abundance differences between intracellular metabolite pools from wild-type and calcium stressed cultures, with and without prior immunosuppressant drugs exposure. We used pathway database content from WikiPathways and YeastCyc to facilitate the projection of our metabolomics profiling results onto biological pathways. A key challenge was to increase the coverage of the detected metabolites. This was achieved by applying both reverse phase (RP and aqueous normal phase (ANP chromatographic separations, as well as electrospray ionization (ESI and atmospheric pressure chemical ionization (APCI sources for detection in both ion polarities. Unsupervised principle component analysis (PCA and ANOVA results revealed differentiation between wild-type controls, calcium stressed and immunosuppressant/calcium challenged cells. Untargeted data mining resulted in 247 differentially expressed, annotated metabolites, across at least one pair of conditions. A separate, targeted data mining strategy identified 187 differential, annotated metabolites. All annotated metabolites were subsequently mapped onto curated pathways from YeastCyc and WikiPathways for interactive pathway analysis and visualization. Dozens of pathways showed differential responses to stress conditions based on one or more matches to the list of annotated metabolites or to metabolites that had been identified further by MS/MS. The purine salvage, pantothenate and sulfur amino acid pathways were flagged as being enriched, which is consistent with previously published

Methods for global sensitivity analysis in life cycle assessment

NARCIS (Netherlands)

Groen, Evelyne A.; Bokkers, Eddy; Heijungs, Reinout; Boer, de Imke J.M.

2017-01-01

Purpose: Input parameters required to quantify environmental impact in life cycle assessment (LCA) can be uncertain due to e.g. temporal variability or unknowns about the true value of emission factors. Uncertainty of environmental impact can be analysed by means of a global sensitivity analysis to

Soil organic matter dynamics and the global carbon cycle

International Nuclear Information System (INIS)

Post, W.M.; Emanuel, W.R.; King, A.W.

1992-01-01

The large size and potentially long residence time of the soil organic matter pool make it an important component of the global carbon cycle. Net terrestrial primary production of about 60 Pg C·yr -1 is, over a several-year period of time, balanced by an equivalent flux of litter production and subsequent decomposition of detritus and soil organic matter. We will review many of the major factors that influence soil organic matter dynamics that need to be explicitly considered in development of global estimates of carbon turnover in the world's soils. We will also discuss current decomposition models that are general enough to be used to develop a representation of global soil organic matter dynamics

In vivo and in vitro cadmium accumulation during the moult cycle of the male shore crab Carcinus maenas-interaction with calcium metabolism

International Nuclear Information System (INIS)

Norum, Ulrik; Bondgaard, Morten; Pedersen, Thomas V.; Bjerregaard, Poul

2005-01-01

The effect of moult stage on cadmium accumulation and distribution was investigated in vivo in male shore crabs Carcinus maenas exposed to 1 mg Cd l -1 for 7 days. The accumulation of cadmium in all tissues examined was markedly higher in postmoult (A 1-2 and B 1-2 ) compared to intermoult (C 1 , C 3 and C 4 ) and premoult (D 0-3 ). In addition, elevated levels of cadmium were found in gills of late premoult (D 2-3 ) animals. The total amount of cadmium accumulated in the tissues (haemolymph, gills, midgut gland and muscle) increased from 43 μg Cd in early premoult (D 0-1 ) to 391 μg Cd in late postmoult (B 1-2 ). Gills and midgut gland were the primary cadmium accumulating tissues in C 4 -intermoult and premoult (D 0-3 ); in early postmoult (A 1-2 ) haemolymph and midgut gland were the main cadmium containing tissues, while midgut gland dominated in late postmoult (B 1-2 ) and early intermoult (C 1 and C 3 ). A detailed account of calcium distribution in haemolymph, gills, midgut gland, muscle and exoskeleton during the moult cycle is presented. Mechanistic links between cadmium and calcium uptake in posterior gills of C 4 -intermoult and early postmoult (A 1-2 ) crabs were explored using an in vitro gill perfusion technique. Calcium and cadmium influxes were markedly higher in postmoult compared to intermoult. No differences between intermoult and postmoult effluxes were found for either calcium or cadmium. From intermoult to postmoult net influx increased from 2.4 to 29 μmol Ca 2+ g -1 ww gill h -1 and from 0.24 to 25 nmol Cd 2+ g -1 ww gill h -1 . The results indicate that the postmoult increase in cadmium influx is due to increased active transport of cadmium, at least partly, by accidental uptake via calcium transporting proteins. The in vitro net influx rates corresponded accurately to the observed in vivo accumulation of both cadmium and calcium. Although cadmium accumulation and distribution are clearly linked to changes in calcium requirements, cadmium

Separating decadal global water cycle variability from sea level rise.

Science.gov (United States)

Hamlington, B D; Reager, J T; Lo, M-H; Karnauskas, K B; Leben, R R

2017-04-20

Under a warming climate, amplification of the water cycle and changes in precipitation patterns over land are expected to occur, subsequently impacting the terrestrial water balance. On global scales, such changes in terrestrial water storage (TWS) will be reflected in the water contained in the ocean and can manifest as global sea level variations. Naturally occurring climate-driven TWS variability can temporarily obscure the long-term trend in sea level rise, in addition to modulating the impacts of sea level rise through natural periodic undulation in regional and global sea level. The internal variability of the global water cycle, therefore, confounds both the detection and attribution of sea level rise. Here, we use a suite of observations to quantify and map the contribution of TWS variability to sea level variability on decadal timescales. In particular, we find that decadal sea level variability centered in the Pacific Ocean is closely tied to low frequency variability of TWS in key areas across the globe. The unambiguous identification and clean separation of this component of variability is the missing step in uncovering the anthropogenic trend in sea level and understanding the potential for low-frequency modulation of future TWS impacts including flooding and drought.

Solar cycle length hypothesis appears to support the IPCC on global warming

DEFF Research Database (Denmark)

Laut, Peter; Gundermann, Jesper

1999-01-01

warming from the enhanced concentrations of greenhouse gases. The "solar hypothesis" claims that solar activity causes a significant component of the global mean temperature to vary in phase opposite to the filtered solar cycle lengths. In an earlier paper we have demonstrated that for data covering...... lengths with the "corrected" temperature anomalies is substantially better than with the historical anomalies. Therefore our findings support a total reversal of the common assumption that a verification of the solar hypothesis would challenge the IPCC assessment of man-made global warming.......Since the discovery of a striking correlation between 1-2-2-2-1 filtered solar cycle lengths and the 11-year running average of Northern Hemisphere land air temperatures there have been widespread speculations as to whether these findings would rule out any significant contributions to global...

An updated view of global water cycling

Science.gov (United States)

Houser, P. R.; Schlosser, A.; Lehr, J.

2009-04-01

Unprecedented new observation capacities combined with revolutions in modeling, we are poised to make huge advances in water cycle assessment, understanding, and prediction. To realize this goal, we must develop a discipline of prediction and verification through the integration of water and energy cycle observations and models, and to verify model predictions against observed phenomena to ensure that research delivers reliable improvements in prediction skill. Accomplishing these goals will require, in part, an accurate accounting of the key reservoirs and fluxes associated with the global water and energy cycle, including their spatial and temporal variability, through integration of all necessary observations and research tools. A brief history of the lineage of the conventional water balance and a summary accounting of all major parameters of the water balance using highly respected secondary sources will be presented. Principally, recently published peer reviewed papers reporting results of original work involving direct measurements and new data generated by high-tech devices (e.g. satellite / airborne instruments, supercomputers, geophysical tools) will be employed. This work lends credence to the conventional water balance ideas, but also reveals anachronistic scientific concepts/models, questionable underlying data, longstanding oversights and outright errors in the water balance.

Modeling of the global carbon cycle - isotopic data requirements

International Nuclear Information System (INIS)

Ciais, P.

1994-01-01

Isotopes are powerful tools to constrain carbon cycle models. For example, the combinations of the CO 2 and the 13 C budget allows to calculate the net-carbon fluxes between atmosphere, ocean, and biosphere. Observations of natural and bomb-produced radiocarbon allow to estimate gross carbon exchange fluxes between different reservoirs and to deduce time scales of carbon overturning in important reservoirs. 18 O in CO 2 is potentially a tool to make the deconvolution of C fluxes within the land biosphere (assimilation vs respirations). The scope of this article is to identify gaps in our present knowledge about isotopes in the light of their use as constraint for the global carbon cycle. In the following we will present a list of some future data requirements for carbon cycle models. (authors)

Global Carbon Cycle of the Precambrian Earth

DEFF Research Database (Denmark)

Wiewióra, Justyna

The carbon isotopic composition of distinct Archaean geological records provides information about the global carbon cycle and emergence of life on early Earth. We utilized carbon isotopic records of Greenlandic carbonatites, diamonds, graphites, marbles, metacarbonates and ultramafic rocks...... in the surface environment and recycled back into the mantle In the third manuscript we investigate the carbon cycle components, which have maintained the carbon isotope composition of the mantle constant through time. Assuming constant organic ratio of the total carbon burial (f), we show that increased.......1‰) and metacarbonate ( -6.1 ± 0.1‰ to +1.5 ± 0.0‰) rocks from the ~3.8 Ga Isua Supracrustal Belt as resulting from the Rayleigh distillation process, which affected the ultramafic reservoir with initial δ13C between -2‰ and 0‰. Due to its high primary δ13C signature, carbon in the Isuan magnesite was most likely...

Global guidance on environmental life cycle impact assessment indicators: Progress and case study

DEFF Research Database (Denmark)

Frischknecht, Rolf; Fantke, Peter; Tschümperlin, Laura

2016-01-01

Purpose The life cycle impact assessment (LCIA) guidance flagship project of the United Nations Environment Programme (UNEP)/Society of Environmental Toxicology and Chemistry (SETAC) Life Cycle Initiative aims at providing global guidance and building scientific consensus on environmental LCIA in...

NEWS Climatology Project: The State of the Water Cycle at Continental to Global Scales

Science.gov (United States)

Rodell, Matthew; LEcuyer, Tristan; Beaudoing, Hiroko Kato; Olson, Bill

2011-01-01

NASA's Energy and Water Cycle Study (NEWS) program fosters collaborative research towards improved quantification and prediction of water and energy cycle consequences of climate change. In order to measure change, it is first necessary to describe current conditions. The goal of the NEWS Water and Energy Cycle Climatology project is to develop "state of the global water cycle" and "state of the global energy cycle" assessments based on data from modern ground and space based observing systems and data integrating models. The project is a multiinstitutional collaboration with more than 20 active contributors. This presentation will describe results of the first stage of the water budget analysis, whose goal was to characterize the current state of the water cycle on mean monthly, continental scales. We examine our success in closing the water budget within the expected uncertainty range and the effects of forcing budget closure as a method for refining individual flux estimates.

Thermodynamic simulation of CO{sub 2} capture for an IGCC power plant using the calcium looping cycle

Energy Technology Data Exchange (ETDEWEB)

Li, Y. [National Engineering Laboratory for Coal-Burning Pollutant Emission Reduction, Shandong University, Jinan (China); Zhao, C.; Ren, Q. [School of Energy and Environment, Southeast University, Nanjing (China)

2011-06-15

A CO{sub 2} capture process for an integrated gasification combined cycle (IGCC) power plant using the calcium looping cycle was proposed. The CO{sub 2} capture process using natural and modified limestone was simulated and investigated with the software package Aspen Plus. It incorporated a fresh feed of sorbent to compensate for the decay in CO{sub 2} capture activity during long-term cycles. The sorbent flow ratios have significant effect on the CO{sub 2} capture efficiency and net efficiency of the CO{sub 2} capture system. The IGCC power plant, using the modified limestone, exhibits higher CO{sub 2} capture efficiency than that using the natural limestone at the same sorbent flow ratios. The system net efficiency using the natural and modified limestones achieves 41.7% and 43.1%, respectively, at the CO{sub 2} capture efficiency of 90% without the effect of sulfation. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Surface Corrosion and Microstructure Degradation of Calcium Sulfoaluminate Cement Subjected to Wet-Dry Cycles in Sulfate Solution

Directory of Open Access Journals (Sweden)

Wuman Zhang

2017-01-01

Full Text Available The hydration products of calcium sulfoaluminate (CSA cement are different from those of Portland cement. The degradation of CSA cement subjected to wet-dry cycles in sulfate solution was studied in this paper. The surface corrosion was recorded and the microstructures were examined by scanning electron microscopy (SEM. The results show that SO42-, Na+, Mg2+, and Cl− have an effect on the stability of ettringite. In the initial period of sulfate attack, salt crystallization is the main factor leading to the degradation of CSA cement specimens. The decomposition and the carbonation of ettringite will cause long-term degradation of CSA cement specimens under wet-dry cycles in sulfate solution. The surface spalling and microstructure degradation increase significantly with the increase of wet-dry cycles, sulfate concentration, and water to cement ratio. Magnesium sulfate and sodium chloride reduce the degradation when the concentration of sulfate ions is a constant value.

Global cycle changes the rules for U.S. pulp and paper

Science.gov (United States)

Peter J. Ince

1999-01-01

As in other industries, the fortunes of the U.S. pulp and paper industry are now closely tied to the global economy. The U.S. pulp and paper sector exhibits fairly steady production and growth trends, but its economic fortunes have become intertwined with the bglobal cyclec of supply and demand. Exposure to the global cycle has increased for the U.S. in recent decades...

Role of Mineral Deposits in Global Geochemical Cycles

Science.gov (United States)

Kesler, S.; Wilkinson, B.

2009-12-01

Mineral deposits represent the most extreme degree of natural concentration for most elements and their formation and destruction are important parts of global geochemical cycles. Quantitative estimates of the role that mineral deposits play in these geochemical cycles has been limited, however, by the lack of information on actual amounts of elements that are concentrated in these deposits, and their rates of formation and destruction at geologic time scales. Recent use of a “tectonic diffusion” model for porphyry copper deposits, the most important source of world copper, in conjunction with estimates of their copper content (Kesler and Wilkinson, 2008), allows an assessment of the role of copper deposits in Earth’s global copper cycles. These results indicate that ~4.5*10^8 Gg of Cu have been concentrated in porphyry copper deposits through Phanerozoic time, that deposits containing ~2.8*10^8 Gg of Cu have been removed by uplift and erosion over the same time period, and that deposits containing ~1.7*10^8 Gg remain in Earth’s crust. If styles of formation and destruction of other copper-bearing mineral deposits are similar, then all crustal deposits contain ~3*10^8 Gg of copper. This constitutes about 0.03% of the copper that resides in crustal rocks and provides a first-ever estimate of the rate at which natural geochemical cycles produce the extreme concentrations that constitute mineral deposits. Another ~8*10^8 Gg of copper have been destroyed during the uplift and erosion of mineral deposits over Phanerozoic time, a flux amounting to an annual contribution of about 1.5 Gg of copper to the near-surface environment. This amount is similar in magnitude to copper released by volcanic outgassing, but only ~2.5% of the 56 Gg of copper estimated to be released annually by weathering of average crustal rocks (Rauch and Graedel, 2007). The amount of copper removed from mineral deposits by mining, 1.1*10^4 Gg/year, is much larger than any natural

Feedback of global warming to soil carbon cycling in forest ecosystems

International Nuclear Information System (INIS)

Nakane, Kaneyuki

1993-01-01

Thus in this study the simulation of soil carbon cycling and dynamics of its storage in several types of mature forests developed from the cool-temperate to the tropics was carried out for quantitatively assessing carbon loss from the soil under several scenarios of global warming, based on the model of soil carbon cycling in forest ecosystems (Nakane et al. 1984, 1987 and Nakane 1992). (J.P.N.)

In vivo and in vitro cadmium accumulation during the moult cycle of the male shore crab Carcinus maenas-interaction with calcium metabolism

Energy Technology Data Exchange (ETDEWEB)

Norum, Ulrik [Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark)]. E-mail: ulrik@biology.sdu.dk; Bondgaard, Morten [Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Pedersen, Thomas V. [Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Bjerregaard, Poul [Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark)

2005-03-25

The effect of moult stage on cadmium accumulation and distribution was investigated in vivo in male shore crabs Carcinus maenas exposed to 1 mg Cd l{sup -1} for 7 days. The accumulation of cadmium in all tissues examined was markedly higher in postmoult (A{sub 1-2} and B{sub 1-2}) compared to intermoult (C{sub 1}, C{sub 3} and C{sub 4}) and premoult (D{sub 0-3}). In addition, elevated levels of cadmium were found in gills of late premoult (D{sub 2-3}) animals. The total amount of cadmium accumulated in the tissues (haemolymph, gills, midgut gland and muscle) increased from 43 {mu}g Cd in early premoult (D{sub 0-1}) to 391 {mu}g Cd in late postmoult (B{sub 1-2}). Gills and midgut gland were the primary cadmium accumulating tissues in C{sub 4}-intermoult and premoult (D{sub 0-3}); in early postmoult (A{sub 1-2}) haemolymph and midgut gland were the main cadmium containing tissues, while midgut gland dominated in late postmoult (B{sub 1-2}) and early intermoult (C{sub 1} and C{sub 3}). A detailed account of calcium distribution in haemolymph, gills, midgut gland, muscle and exoskeleton during the moult cycle is presented. Mechanistic links between cadmium and calcium uptake in posterior gills of C{sub 4}-intermoult and early postmoult (A{sub 1-2}) crabs were explored using an in vitro gill perfusion technique. Calcium and cadmium influxes were markedly higher in postmoult compared to intermoult. No differences between intermoult and postmoult effluxes were found for either calcium or cadmium. From intermoult to postmoult net influx increased from 2.4 to 29 {mu}mol Ca{sup 2+} g{sup -1} ww{sub gill} h{sup -1} and from 0.24 to 25 nmol Cd{sup 2+} g{sup -1} ww{sub gill} h{sup -1}. The results indicate that the postmoult increase in cadmium influx is due to increased active transport of cadmium, at least partly, by accidental uptake via calcium transporting proteins. The in vitro net influx rates corresponded accurately to the observed in vivo accumulation of both cadmium

The oceanic cycle and global atmospheric budget of carbonyl sulfide

Energy Technology Data Exchange (ETDEWEB)

Weiss, P.S.

1994-12-31

A significant portion of stratospheric air chemistry is influenced by the existence of carbonyl sulfide (COS). This ubiquitous sulfur gas represents a major source of sulfur to the stratosphere where it is converted to sulfuric acid aerosol particles. Stratospheric aerosols are climatically important because they scatter incoming solar radiation back to space and are able to increase the catalytic destruction of ozone through gas phase reactions on particle surfaces. COS is primarily formed at the surface of the earth, in both marine and terrestrial environments, and is strongly linked to natural biological processes. However, many gaps in the understanding of the global COS cycle still exist, which has led to a global atmospheric budget that is out of balance by a factor of two or more, and a lack of understanding of how human activity has affected the cycling of this gas. The goal of this study was to focus on COS in the marine environment by investigating production/destruction mechanisms and recalculating the ocean-atmosphere flux.

Regulation of cardiomyocyte autophagy by calcium.

Science.gov (United States)

Shaikh, Soni; Troncoso, Rodrigo; Criollo, Alfredo; Bravo-Sagua, Roberto; García, Lorena; Morselli, Eugenia; Cifuentes, Mariana; Quest, Andrew F G; Hill, Joseph A; Lavandero, Sergio

2016-04-15

Calcium signaling plays a crucial role in a multitude of events within the cardiomyocyte, including cell cycle control, growth, apoptosis, and autophagy. With respect to calcium-dependent regulation of autophagy, ion channels and exchangers, receptors, and intracellular mediators play fundamental roles. In this review, we discuss calcium-dependent regulation of cardiomyocyte autophagy, a lysosomal mechanism that is often cytoprotective, serving to defend against disease-related stress and nutrient insufficiency. We also highlight the importance of the subcellular distribution of calcium and related proteins, interorganelle communication, and other key signaling events that govern cardiomyocyte autophagy. Copyright © 2016 the American Physiological Society.

Summertime calcium carbonate undersaturation in shelf waters of the western Arctic Ocean – how biological processes exacerbate the impact of ocean acidification

OpenAIRE

N. R. Bates; M. I. Orchowska; R. Garley; J. T. Mathis

2013-01-01

The Arctic Ocean accounts for only 4% of the global ocean area, but it contributes significantly to the global carbon cycle. Recent observations of seawater CO2-carbonate chemistry in shelf waters of the western Arctic Ocean, primarily in the Chukchi Sea, from 2009 to 2011 indicate that bottom waters are seasonally undersaturated with respect to calcium carbonate (CaCO3) minerals, particularly aragonite. Nearly 40% of sampled bottom waters on the shelf have saturation states...

Proceedings of GLOBAL 2007 conference on advanced nuclear fuel cycles and systems

International Nuclear Information System (INIS)

2007-01-01

In keeping with the 12-year history of this conference, GLOBAL 2007 focuses on future nuclear energy systems and fuel cycles. With the increasing public acceptance and political endorsement of nuclear energy, it is a pivotal time for nuclear energy research. Significant advances have been made in development of advanced nuclear fuels and materials, reactor designs, partitioning, transmutation and reprocessing technologies, and waste management strategies. In concert with the technological advances, it is more important than ever to develop sensible nuclear proliferation policies, to promote sustainability, and to continue to increase international collaboration. To further these aims, GLOBAL 2007 highlights recent developments in the following areas: advanced integrated fuel cycle concepts, spent nuclear fuel reprocessing, advanced reprocessing technology, advanced fuels and materials, advanced waste management technology, novel concepts for waste disposal and repository development, advanced reactors, partitioning and transmutation, developments in nuclear non-proliferation technology, policy, and implementation, sustainability and expanded global utilization of nuclear energy, and international collaboration on nuclear energy

Biogenic sulfur compounds and the global sulfur cycle

International Nuclear Information System (INIS)

Aneja, V.P.; Aneja, A.P.; Adams, D.F.

1982-01-01

Field measurements of biogenic sulfur compounds shows a great variation in concentrations and emission rates for H 2 S, DMS, CS 2 and COS. Measurements by the chamber method and estimates from micrometeorological sampling are employed to determine the earth-atmosphere flux of these gases. Much of the variation can be attributed to differences of climate and surface conditions, with marshes being a large source of biogenic sulfur (mean contribution 4 x 10 to the 6th ton/year maximum contribution 142 x 10 to the 6th ton/year). Considering that the estimated biogenic contribution needed to balance the global sulfur cycle ranges from 40- 230 x 10 to the 6th tons/year, the mean values are not sufficient to balance this cycle. Further experimental investigations are suggested in order to characterize the biogenic processes adequately

Formulating Energy Policies Related to Fossil Fuel Use: Critical Uncertainties in the Global Carbon Cycle

Science.gov (United States)

Post, W. M.; Dale, V. H.; DeAngelis, D. L.; Mann, L. K.; Mulholland, P. J.; O`Neill, R. V.; Peng, T. -H.; Farrell, M. P.

1990-02-01

The global carbon cycle is the dynamic interaction among the earth's carbon sources and sinks. Four reservoirs can be identified, including the atmosphere, terrestrial biosphere, oceans, and sediments. Atmospheric CO{sub 2} concentration is determined by characteristics of carbon fluxes among major reservoirs of the global carbon cycle. The objective of this paper is to document the knowns, and unknowns and uncertainties associated with key questions that if answered will increase the understanding of the portion of past, present, and future atmospheric CO{sub 2} attributable to fossil fuel burning. Documented atmospheric increases in CO{sub 2} levels are thought to result primarily from fossil fuel use and, perhaps, deforestation. However, the observed atmospheric CO{sub 2} increase is less than expected from current understanding of the global carbon cycle because of poorly understood interactions among the major carbon reservoirs.

Movement of calcium signals and calcium-binding proteins: firewalls, traps and tunnels.

Science.gov (United States)

Barrow, S L; Sherwood, M W; Dolman, N J; Gerasimenko, O V; Voronina, S G; Tepikin, A V

2006-06-01

In the board game 'Snakes and Ladders', placed on the image of a pancreatic acinar cell, calcium ions have to move from release sites in the secretory region to the nucleus. There is another important contraflow - from calcium entry channels in the basal part of the cell to ER (endoplasmic reticulum) terminals in the secretory granule region. Both transport routes are perilous as the messenger can disappear in any place on the game board. It can be grabbed by calcium ATPases of the ER (masquerading as a snake but functioning like a ladder) and tunnelled through its low buffering environment, it can be lured into the whirlpools of mitochondria uniporters and forced to regulate the tricarboxylic acid cycle, and it can be permanently placed inside the matrix of secretory granules and released only outside the cell. The organelles could trade calcium (e.g. from the ER to mitochondria and vice versa) almost depriving this ion the light of the cytosol and noble company of cytosolic calcium buffers. Altogether it is a rich and colourful story.

On the linkages between the global carbon-nitrogen-phosphorus cycles

Science.gov (United States)

Tanaka, Katsumasa; Mackenzie, Fred; Bouchez, Julien; Knutti, Reto

2013-04-01

State-of-the-art earth system models used for long-term climate projections are becoming ever more complex in terms of not only spatial resolution but also the number of processes. Biogeochemical processes are beginning to be incorporated into these models. The motivation of this study is to quantify how climate projections are influenced by biogeochemical feedbacks. In the climate modeling community, it is virtually accepted that climate-Carbon (C) cycle feedbacks accelerate the future warming (Cox et al. 2000; Friedlingstein et al. 2006). It has been demonstrated that the Nitrogen (N) cycle suppresses climate-C cycle feedbacks (Thornton et al. 2009). On the contrary, biogeochemical studies show that the coupled C-N-Phosphorus (P) cycles are intimately interlinked via biosphere and the N-P cycles amplify C cycle feedbacks (Ver et al. 1999). The question as to whether the N-P cycles enhance or attenuate C cycle feedbacks is debated and has a significant implication for projections of future climate. We delve into this problem by using the Terrestrial-Ocean-aTmosphere Ecosystem Model 3 (TOTEM3), a globally-aggregated C-N-P cycle box model. TOTEM3 is a process-based model that describes the biogeochemical reactions and physical transports involving these elements in the four domains of the Earth system: land, atmosphere, coastal ocean, and open ocean. TOTEM3 is a successor of earlier TOTEM models (Ver et al. 1999; Mackenzie et al. 2011). In our presentation, we provide an overview of fundamental features and behaviors of TOTEM3 such as the mass balance at the steady state and the relaxation time scales to various types of perturbation. We also show preliminary results to investigate how the N-P cycles influence the behavior of the C cycle. References Cox PM, Betts RA, Jones CD, Spall SA, Totterdell IJ (2000) Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model. Nature, 408, 184-187. Friedlingstein P, Cox P, Betts R, Bopp L, von Bloh

Atomic layer deposition of calcium oxide and calcium hafnium oxide films using calcium cyclopentadienyl precursor

International Nuclear Information System (INIS)

Kukli, Kaupo; Ritala, Mikko; Sajavaara, Timo; Haenninen, Timo; Leskelae, Markku

2006-01-01

Calcium oxide and calcium hafnium oxide thin films were grown by atomic layer deposition on borosilicate glass and silicon substrates in the temperature range of 205-300 o C. The calcium oxide films were grown from novel calcium cyclopentadienyl precursor and water. Calcium oxide films possessed refractive index 1.75-1.80. Calcium oxide films grown without Al 2 O 3 capping layer occurred hygroscopic and converted to Ca(OH) 2 after exposure to air. As-deposited CaO films were (200)-oriented. CaO covered with Al 2 O 3 capping layers contained relatively low amounts of hydrogen and re-oriented into (111) direction upon annealing at 900 o C. In order to examine the application of CaO in high-permittivity dielectric layers, mixtures of Ca and Hf oxides were grown by alternate CaO and HfO 2 growth cycles at 230 and 300 o C. HfCl 4 was used as a hafnium precursor. When grown at 230 o C, the films were amorphous with equal amounts of Ca and Hf constituents (15 at.%). These films crystallized upon annealing at 750 o C, showing X-ray diffraction peaks characteristic of hafnium-rich phases such as Ca 2 Hf 7 O 16 or Ca 6 Hf 19 O 44 . At 300 o C, the relative Ca content remained below 8 at.%. The crystallized phase well matched with rhombohedral Ca 2 Hf 7 O 16 . The dielectric films grown on Si(100) substrates possessed effective permittivity values in the range of 12.8-14.2

The terrestrial carbon cycle on the regional and global scale : modeling, uncertainties and policy relevance

NARCIS (Netherlands)

Minnen, van J.G.

2008-01-01

Contains the chapters: The importance of three centuries of climate and land-use change for the global and regional terrestrial carbon cycle; and The terrestrial C cycle and its role in the climate change policy

Global biogeochemical cycle of vanadium.

Science.gov (United States)

Schlesinger, William H; Klein, Emily M; Vengosh, Avner

2017-12-26

Synthesizing published data, we provide a quantitative summary of the global biogeochemical cycle of vanadium (V), including both human-derived and natural fluxes. Through mining of V ores (130 × 10 9 g V/y) and extraction and combustion of fossil fuels (600 × 10 9 g V/y), humans are the predominant force in the geochemical cycle of V at Earth's surface. Human emissions of V to the atmosphere are now likely to exceed background emissions by as much as a factor of 1.7, and, presumably, we have altered the deposition of V from the atmosphere by a similar amount. Excessive V in air and water has potential, but poorly documented, consequences for human health. Much of the atmospheric flux probably derives from emissions from the combustion of fossil fuels, but the magnitude of this flux depends on the type of fuel, with relatively low emissions from coal and higher contributions from heavy crude oils, tar sands bitumen, and petroleum coke. Increasing interest in petroleum derived from unconventional deposits is likely to lead to greater emissions of V to the atmosphere in the near future. Our analysis further suggests that the flux of V in rivers has been incremented by about 15% from human activities. Overall, the budget of dissolved V in the oceans is remarkably well balanced-with about 40 × 10 9 g V/y to 50 × 10 9 g V/y inputs and outputs, and a mean residence time for dissolved V in seawater of about 130,000 y with respect to inputs from rivers.

Calcium addition in straw gasification

DEFF Research Database (Denmark)

Risnes, H.; Fjellerup, Jan Søren; Henriksen, Ulrik Birk

2003-01-01

The present work focuses on the influence of calcium addition in gasification. The inorganic¿organic element interaction as well as the detailed inorganic¿inorganic elements interaction has been studied. The effect of calcium addition as calcium sugar/molasses solutions to straw significantly...... affected the ash chemistry and the ash sintering tendency but much less the char reactivity. Thermo balance test are made and high-temperature X-ray diffraction measurements are performed, the experimental results indicate that with calcium addition major inorganic¿inorganic reactions take place very late...... in the char conversion process. Comprehensive global equilibrium calculations predicted important characteristics of the inorganic ash residue. Equilibrium calculations predict the formation of liquid salt if sufficient amounts of Ca are added and according to experiments as well as calculations calcium binds...

Global water cycle amplifying at less than the Clausius-Clapeyron rate

OpenAIRE

Skliris, Nikolaos; Zika, Jan D.; Nurser, George; Josey, Simon A.; Marsh, Robert

2016-01-01

A change in the cycle of water from dry to wet regions of the globe would have far reaching impact on humanity. As air warms, its capacity to hold water increases at the Clausius-Clapeyron rate (CC, approximately 7%?°C?1). Surface ocean salinity observations have suggested the water cycle has amplified at close to CC following recent global warming, a result that was found to be at odds with state-of the art climate models. Here we employ a method based on water mass transformation theory for...

A Seamless Framework for Global Water Cycle Monitoring and Prediction

Science.gov (United States)

Sheffield, J.; Wood, E. F.; Chaney, N.; Fisher, C. K.; Caylor, K. K.

2013-12-01

The Global Earth Observation System of Systems (GEOSS) Water Strategy ('From Observations to Decisions') recognizes that 'water is essential for ensuring food and energy security, for facilitating poverty reduction and health security, and for the maintenance of ecosystems and biodiversity', and that water cycle data and observations are critical for improved water management and water security - especially in less developed regions. The GEOSS Water Strategy has articulated a number of goals for improved water management, including flood and drought preparedness, that include: (i) facilitating the use of Earth Observations for water cycle observations; (ii) facilitating the acquisition, processing, and distribution of data products needed for effective management; (iii) providing expertise, information systems, and datasets to the global, regional, and national water communities. There are several challenges that must be met to advance our capability to provide near real-time water cycle monitoring, early warning of hydrological hazards (floods and droughts) and risk assessment under climate change, regionally and globally. Current approaches to monitoring and predicting hydrological hazards are limited in many parts of the world, and especially in developing countries where national capacity is limited and monitoring networks are inadequate. This presentation describes the development of a seamless monitoring and prediction framework at all time scales that allows for consistent assessment of water variability from historic to current conditions, and from seasonal and decadal predictions to climate change projections. At the center of the framework is an experimental, global water cycle monitoring and seasonal forecast system that has evolved out of regional and continental systems for the US and Africa. The system is based on land surface hydrological modeling that is driven by satellite remote sensing precipitation to predict current hydrological conditions

GEWEX - The Global Energy and Water Cycle Experiment

Science.gov (United States)

Chahine, Moustafa T.

1992-01-01

GEWEX, which is part of the World Climate Research Program, has as its goal an order-of-magnitude improvement in the ability to model global precipitation and evaporation and furnish an accurate assessment of the sensitivity of atmospheric radiation and clouds. Attention will also be given to the response of the hydrological cycle and water resources to climate change. GEWEX employs a single program to coordinate all aspects of climatology from model development to the deployment and operation of observational systems. GEWEX will operate over the next two decades.

Glacial-interglacial water cycle, global monsoon and atmospheric methane changes

Energy Technology Data Exchange (ETDEWEB)

Guo, Zhengtang; Wu, Haibin [Chinese Academy of Sciences, Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Beijing (China); Zhou, Xin [Chinese Academy of Sciences, Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Beijing (China); University of Science and Technology of China, School of Earth and Space Sciences and Institute of Polar Environment, Hefei (China)

2012-09-15

The causes of atmospheric methane (CH{sub 4}) changes are still a major contention, in particular with regards to the relative contributions of glacial-interglacial cycles, monsoons in both hemispheres and the late Holocene human intervention. Here, we explore the CH{sub 4} signals in the Antarctic EPICA Dome C and Vostok ice records using the methods of timeseries analyses and correlate them with insolation and geological records to address these issues. The results parse out three distinct groups of CH{sub 4} signals attributable to different drivers. The first group ({proportional_to}80% variance), well tracking the marine {delta}{sup 18}O record, is attributable to glacial-interglacial modulation on the global water cycle with the effects shared by wetlands at all latitudes, from monsoonal and non-monsoonal regions in both hemispheres. The second group ({proportional_to}15% variance), centered at the {proportional_to}10-kyr semi-precession frequency, is linkable with insolation-driven tropical monsoon changes in both hemispheres. The third group ({proportional_to}5% variance), marked by millennial frequencies, is seemingly related with the combined effect of ice-volume and bi-hemispheric insolation changes at the precession bands. These results indicate that bi-hemispheric monsoon changes have been a constant driver of atmospheric CH{sub 4}. This mechanism also partially explains the Holocene CH{sub 4} reversal since {proportional_to}5 kyr BP besides the human intervention. In the light of these results, we propose that global monsoon can be regarded as a system consisting of two main integrated components, one primarily driven by the oscillations of Inter-Tropical Convergence Zone (ITCZ) in response to the low-latitude summer insolation changes, anti-phase between the two hemispheres (i.e. the ITCZ monsoon component); and another modulated by the glacial-interglacial cycles, mostly synchronous at the global scale (i.e. the glacial-interglacial monsoon

A Review of the Stable Isotope Bio-geochemistry of the Global Silicon Cycle and Its Associated Trace Elements

Directory of Open Access Journals (Sweden)

Jill N. Sutton

2018-01-01

Full Text Available Silicon (Si is the second most abundant element in the Earth's crust and is an important nutrient in the ocean. The global Si cycle plays a critical role in regulating primary productivity and carbon cycling on the continents and in the oceans. Development of the analytical tools used to study the sources, sinks, and fluxes of the global Si cycle (e.g., elemental and stable isotope ratio data for Ge, Si, Zn, etc. have recently led to major advances in our understanding of the mechanisms and processes that constrain the cycling of Si in the modern environment and in the past. Here, we provide background on the geochemical tools that are available for studying the Si cycle and highlight our current understanding of the marine, freshwater and terrestrial systems. We place emphasis on the geochemistry (e.g., Al/Si, Ge/Si, Zn/Si, δ13C, δ15N, δ18O, δ30Si of dissolved and biogenic Si, present case studies, such as the Silicic Acid Leakage Hypothesis, and discuss challenges associated with the development of these environmental proxies for the global Si cycle. We also discuss how each system within the global Si cycle might change over time (i.e., sources, sinks, and processes and the potential technical and conceptual limitations that need to be considered for future studies.

Should we expect financial globalization to have significant effects on business cycles?

OpenAIRE

Iversen, Jens

2009-01-01

Empirical research suggests that financial globalization has insignificant effects on business cycles. Based on standard theoretical models it might be conjectured that the effects should be significant. I show that this conjecture is wrong. Theoretical effects of financial globalization can be determined to any level of precision by expanding the underlying artificial samples. In contrast, in the data the effects are imprecisely estimated because of short samples. I show that if the conclusi...

Role of volcanic forcing on future global carbon cycle

Directory of Open Access Journals (Sweden)

J. F. Tjiputra

2011-06-01

Full Text Available Using a fully coupled global climate-carbon cycle model, we assess the potential role of volcanic eruptions on future projection of climate change and its associated carbon cycle feedback. The volcanic-like forcings are applied together with a business-as-usual IPCC-A2 carbon emissions scenario. We show that very large volcanic eruptions similar to Tambora lead to short-term substantial global cooling. However, over a long period, smaller eruptions similar to Pinatubo in amplitude, but set to occur frequently, would have a stronger impact on future climate change. In a scenario where the volcanic external forcings are prescribed with a five-year frequency, the induced cooling immediately lower the global temperature by more than one degree before it returns to the warming trend. Therefore, the climate change is approximately delayed by several decades, and by the end of the 21st century, the warming is still below two degrees when compared to the present day period. Our climate-carbon feedback analysis shows that future volcanic eruptions induce positive feedbacks (i.e., more carbon sink on both the terrestrial and oceanic carbon cycle. The feedback signal on the ocean is consistently smaller than the terrestrial counterpart and the feedback strength is proportionally related to the frequency of the volcanic eruption events. The cooler climate reduces the terrestrial heterotrophic respiration in the northern high latitude and increases net primary production in the tropics, which contributes to more than 45 % increase in accumulated carbon uptake over land. The increased solubility of CO₂ gas in seawater associated with cooler SST is offset by a reduced CO₂ partial pressure gradient between the ocean and the atmosphere, which results in small changes in net ocean carbon uptake. Similarly, there is nearly no change in the seawater buffer capacity simulated between the different volcanic scenarios. Our study shows that even

Tree species effects on calcium cycling: The role of calcium uptake in deep soils

NARCIS (Netherlands)

Dijkstra, F.A.; Smits, M.M.

2002-01-01

Soil acidity and calcium (Ca) availability in the surface soil differ substantially beneath sugar maple (Acer saccharum) and eastern hemlock (Tsuga canadensis) trees in a mixed forest in northwestern Connecticut. We determined the effect of pumping of Ca from deep soil (rooting zone below 20-cm

A simple global carbon and energy coupled cycle model for global warming simulation: sensitivity to the light saturation effect

International Nuclear Information System (INIS)

Ichii, Kazuhito; Murakami, Kazutaka; Mukai, Toshikazu; Yamaguchi, Yasushi; Ogawa, Katsuro

2003-01-01

A simple Earth system model, the Four-Spheres Cycle of Energy and Mass (4-SCEM) model, has been developed to simulate global warming due to anthropogenic CO 2 emission. The model consists of the Atmosphere-Earth Heat Cycle (AEHC) model, the Four Spheres Carbon Cycle (4-SCC) model, and their feedback processes. The AEHC model is a one-dimensional radiative convective model, which includes the greenhouse effect of CO 2 and H 2 O, and one cloud layer. The 4-SCC model is a box-type carbon cycle model, which includes biospheric CO 2 fertilization, vegetation area variation, the vegetation light saturation effect and the HILDA oceanic carbon cycle model. The feedback processes between carbon cycle and climate considered in the model are temperature dependencies of water vapor content, soil decomposition and ocean surface chemistry. The future status of the global carbon cycle and climate was simulated up to the year 2100 based on the 'business as usual' (IS92a) emission scenario, followed by a linear decline in emissions to zero in the year 2200. The atmospheric CO 2 concentration reaches 645 ppmv in 2100 and a peak of 760 ppmv approximately in the year 2170, and becomes a steady state with 600 ppmv. The projected CO 2 concentration was lower than those of the past carbon cycle studies, because we included the light saturation effect of vegetation. The sensitivity analysis showed that uncertainties derived from the light saturation effect of vegetation and land use CO 2 emissions were the primary cause of uncertainties in projecting future CO 2 concentrations. The climate feedback effects showed rather small sensitivities compared with the impacts of those two effects. Satellite-based net primary production trends analyses can somewhat decrease the uncertainty in quantifying CO 2 emissions due to land use changes. On the other hand, as the estimated parameter in vegetation light saturation was poorly constrained, we have to quantify and constrain the effect more

East Asian Financial Cycles: Asian vs. Global Financial Crises

OpenAIRE

Akira Kohsaka; Jun-ichi Shinkai

2014-01-01

We examine the role of financial shocks in business cycles in general and in financial crises in particular in East Asia (Indonesia, Korea, Malaysia and Thailand) since the 1990s. Estimating a Financial Conditions Index, we found that financial shocks explain most of business downturns in all the economies in the Asian Financial Crisis (AFC) in 1997-98, but that the effects of financial shocks are diverse across economies in the Global Financial Crisis (GFC) in 2008-09. In the GFC, the financ...

Albedo enhancement of marine clouds to counteract global warming: impacts on the hydrological cycle

Energy Technology Data Exchange (ETDEWEB)

Bala, G. [Indian Institute of Science, Divecha Center for Climate Change, Bangalore (India); Indian Institute of Science, Center for Atmospheric and Oceanic Sciences, Bangalore (India); Caldeira, Ken; Cao, Long; Ban-Weiss, George; Shin, Ho-Jeong [Carnegie Institution, Department of Global Ecology, Stanford, CA (United States); Nemani, Rama [NASA Ames Research Center, Moffett Field, CA (United States)

2011-09-15

Recent studies have shown that changes in solar radiation affect the hydrological cycle more strongly than equivalent CO{sub 2} changes for the same change in global mean surface temperature. Thus, solar radiation management ''geoengineering'' proposals to completely offset global mean temperature increases by reducing the amount of absorbed sunlight might be expected to slow the global water cycle and reduce runoff over land. However, proposed countering of global warming by increasing the albedo of marine clouds would reduce surface solar radiation only over the oceans. Here, for an idealized scenario, we analyze the response of temperature and the hydrological cycle to increased reflection by clouds over the ocean using an atmospheric general circulation model coupled to a mixed layer ocean model. When cloud droplets are reduced in size over all oceans uniformly to offset the temperature increase from a doubling of atmospheric CO{sub 2}, the global-mean precipitation and evaporation decreases by about 1.3% but runoff over land increases by 7.5% primarily due to increases over tropical land. In the model, more reflective marine clouds cool the atmospheric column over ocean. The result is a sinking motion over oceans and upward motion over land. We attribute the increased runoff over land to this increased upward motion over land when marine clouds are made more reflective. Our results suggest that, in contrast to other proposals to increase planetary albedo, offsetting mean global warming by reducing marine cloud droplet size does not necessarily lead to a drying, on average, of the continents. However, we note that the changes in precipitation, evaporation and P-E are dominated by small but significant areas, and given the highly idealized nature of this study, a more thorough and broader assessment would be required for proposals of altering marine cloud properties on a large scale. (orig.)

Consequences of the cultivation of energy crops for the global nitrogen cycle

NARCIS (Netherlands)

Bouwman, A.F.; Grinsven, van J.J.M.; Eickhout, B.

2010-01-01

In this paper, we assess the global consequences of implementing first- and second-generation bioenergy in the coming five decades, focusing on the nitrogen cycle. We Use a climate mitigation scenario from the Organization for Economic Cooperation and Development's (OECD) Environmental Outlook, in

Immobilization of calcium sulfate contained in demolition waste

International Nuclear Information System (INIS)

Ambroise, J.; Pera, J.

2008-01-01

This paper presents the results of a laboratory study undertaken to examine the treatment of demolition waste containing calcium sulfate by means of calcium sulfoaluminate clinker (CSA). The quantity of CSA necessary to entirely consume calcium sulfate was determined. Using infrared spectrometry analysis and X-ray diffraction, it was shown that calcium sulfate was entirely consumed when the ratio between CSA and calcium sulfate was 4. Standard sand was polluted by 4% calcium sulfate. Two solutions were investigated: ·either global treatment of sand by CSA, ·or immobilization of calcium sulfate by CSA, followed by the introduction of this milled mixture in standard sand. Regardless of the type of treatment, swelling was almost stabilized after 28 days of immersion in water

Effects of global change during the 21st century onthe nitrogen cycle

Science.gov (United States)

Fowler, D.; Steadman, C. E.; Stevenson, D.; Coyle, M.; Rees, R. M.; Skiba, U. M.; Sutton, M. A.; Cape, J. N.; Dore, A. J.; Vieno, M.; Simpson, D.; Zaehle, S.; Stocker, B. D.; Rinaldi, M.; Facchini, M. C.; Flechard, C. R.; Nemitz, E.; Twigg, M.; Erisman, J. W.; Butterbach-Bahl, K.; Galloway, J. N.

2015-12-01

The global nitrogen (N) cycle at the beginning of the 21st century has been shown to be strongly influenced by the inputs of reactive nitrogen (Nr) from human activities, including combustion-related NOx, industrial and agricultural N fixation, estimated to be 220 Tg N yr-1 in 2010, which is approximately equal to the sum of biological N fixation in unmanaged terrestrial and marine ecosystems. According to current projections, changes in climate and land use during the 21st century will increase both biological and anthropogenic fixation, bringing the total to approximately 600 Tg N yr-1 by around 2100. The fraction contributed directly by human activities is unlikely to increase substantially if increases in nitrogen use efficiency in agriculture are achieved and control measures on combustion-related emissions implemented. Some N-cycling processes emerge as particularly sensitive to climate change. One of the largest responses to climate in the processing of Nr is the emission to the atmosphere of NH3, which is estimated to increase from 65 Tg N yr-1 in 2008 to 93 Tg N yr-1 in 2100 assuming a change in global surface temperature of 5 °C in the absence of increased anthropogenic activity. With changes in emissions in response to increased demand for animal products the combined effect would be to increase NH3 emissions to 135 Tg N yr-1. Another major change is the effect of climate changes on aerosol composition and specifically the increased sublimation of NH4NO3 close to the ground to form HNO3 and NH3 in a warmer climate, which deposit more rapidly to terrestrial surfaces than aerosols. Inorganic aerosols over the polluted regions especially in Europe and North America were dominated by (NH4)2SO4 in the 1970s to 1980s, and large reductions in emissions of SO2 have removed most of the SO42- from the atmosphere in these regions. Inorganic aerosols from anthropogenic emissions are now dominated by NH4NO3, a volatile aerosol which contributes substantially to PM10

Global Water Cycle Agreement in the Climate Models Assessed in the IPCC AR4

Science.gov (United States)

Waliser, D.; Seo, K. -W.; Schubert, S.; Njoku, E.

2007-01-01

This study examines the fidelity of the global water cycle in the climate model simulations assessed in the IPCC Fourth Assessment Report. The results demonstrate good model agreement in quantities that have had a robust global observational basis and that are physically unambiguous. The worst agreement occurs for quantities that have both poor observational constraints and whose model representations can be physically ambiguous. In addition, components involving water vapor (frozen water) typically exhibit the best (worst) agreement, and fluxes typically exhibit better agreement than reservoirs. These results are discussed in relation to the importance of obtaining accurate model representation of the water cycle and its role in climate change. Recommendations are also given for facilitating the needed model improvements.

CO{sub 2} capture efficiency and energy requirement analysis of power plant using modified calcium-based sorbent looping cycle

Energy Technology Data Exchange (ETDEWEB)

Li, Y.J.; Zhao, C.S.; Chen, H.C.; Ren, Q.Q.; Duan, L.B. [Southeast University, Nanjing (China). School of Energy & Environment

2011-03-15

This paper examines the average carbonation conversion, CO{sub 2} capture efficiency and energy requirement for post-combustion CO{sub 2} capture system during the modified calcium-based sorbent looping cycle. The limestone modified with acetic acid solution, i.e. calcium acetate is taken as an example of the modified calcium-based sorbents. The modified limestone exhibits much higher average carbonation conversion than the natural sorbent under the same condition. The CO{sub 2} capture efficiency increases with the sorbent flow ratios. Compared with the natural limestone, much less makeup mass flow of the recycled and the fresh sorbent is needed for the system when using the modified limestone at the same CO{sub 2} capture efficiency. Achieving 0.95 of CO{sub 2} capture efficiency without sulfation, 272 kJ/mol CO{sub 2} is required in the calciner for the natural limestone, whereas only 223 kJ/mol CO{sub 2} for the modified sorbent. The modified limestone possesses greater advantages in CO{sub 2} capture efficiency and energy consumption than the natural sorbent. When the sulfation and carbonation of the sorbents take place simultaneously, more energy is required. It is significantly necessary to remove SO{sub 2} from the flue gas before it enters the carbonator in order to reduce energy consumption in the calciner.

Global operational hydrological forecasts through eWaterCycle

Science.gov (United States)

van de Giesen, Nick; Bierkens, Marc; Donchyts, Gennadii; Drost, Niels; Hut, Rolf; Sutanudjaja, Edwin

2015-04-01

Central goal of the eWaterCycle project (www.ewatercycle.org) is the development of an operational hyper-resolution hydrological global model. This model is able to produce 14 day ensemble forecasts based on a hydrological model and operational weather data (presently NOAA's Global Ensemble Forecast System). Special attention is paid to prediction of situations in which water related issues are relevant, such as floods, droughts, navigation, hydropower generation, and irrigation stress. Near-real time satellite data will be assimilated in the hydrological simulations, which is a feature that will be presented for the first time at EGU 2015. First, we address challenges that are mainly computer science oriented but have direct practical hydrological implications. An important feature in this is the use of existing standards and open-source software to the maximum extent possible. For example, we use the Community Surface Dynamics Modeling System (CSDMS) approach to coupling models (Basic Model Interface (BMI)). The hydrological model underlying the project is PCR-GLOBWB, built by Utrecht University. This is the motor behind the predictions and state estimations. Parts of PCR-GLOBWB have been re-engineered to facilitate running it in a High Performance Computing (HPC) environment, run parallel on multiple nodes, as well as to use BMI. Hydrological models are not very CPU intensive compared to, say, atmospheric models. They are, however, memory hungry due to the localized processes and associated effective parameters. To accommodate this memory need, especially in an ensemble setting, a variation on the traditional Ensemble Kalman Filter was developed that needs much less on-chip memory. Due to the operational nature, the coupling of the hydrological model with hydraulic models is very important. The idea is not to run detailed hydraulic routing schemes over the complete globe but to have on-demand simulation prepared off-line with respect to topography and

Role of zooplankton dynamics for Southern Ocean phytoplankton biomass and global biogeochemical cycles

DEFF Research Database (Denmark)

Le Quéré, Corinne; Buitenhuis, Erik T.; Moriarty, Róisín

2016-01-01

zooplankton community, despite iron limitation of phytoplankton community growth rates. This result has implications for the representation of global biogeochemical cycles in models as zooplankton faecal pellets sink rapidly and partly control the carbon export to the intermediate and deep ocean....

Plumbing the global carbon cycle: Integrating inland waters into the terrestrial carbon budget

NARCIS (Netherlands)

Cole, J.; Prairie, Y.T.; Caraco, N.; McDowell, W.H.; Tranvil, L.; Striegl, R.G.; Duarte, C.M.; Kortelainen, P.; Downing, J.A.; Middelburg, J.J.; Melack, J.

2007-01-01

Because freshwater covers such a small fraction of the Earth’s surface area, inland freshwater ecosystems (particularly lakes, rivers, and reservoirs) have rarely been considered as potentially important quantitative components of the carbon cycle at either global or regional scales. By taking

eWaterCycle: A global operational hydrological forecasting model

Science.gov (United States)

van de Giesen, Nick; Bierkens, Marc; Donchyts, Gennadii; Drost, Niels; Hut, Rolf; Sutanudjaja, Edwin

2015-04-01

Development of an operational hyper-resolution hydrological global model is a central goal of the eWaterCycle project (www.ewatercycle.org). This operational model includes ensemble forecasts (14 days) to predict water related stress around the globe. Assimilation of near-real time satellite data is part of the intended product that will be launched at EGU 2015. The challenges come from several directions. First, there are challenges that are mainly computer science oriented but have direct practical hydrological implications. For example, we aim to make use as much as possible of existing standards and open-source software. For example, different parts of our system are coupled through the Basic Model Interface (BMI) developed in the framework of the Community Surface Dynamics Modeling System (CSDMS). The PCR-GLOBWB model, built by Utrecht University, is the basic hydrological model that is the engine of the eWaterCycle project. Re-engineering of parts of the software was needed for it to run efficiently in a High Performance Computing (HPC) environment, and to be able to interface using BMI, and run on multiple compute nodes in parallel. The final aim is to have a spatial resolution of 1km x 1km, which is currently 10 x 10km. This high resolution is computationally not too demanding but very memory intensive. The memory bottleneck becomes especially apparent for data assimilation, for which we use OpenDA. OpenDa allows for different data assimilation techniques without the need to build these from scratch. We have developed a BMI adaptor for OpenDA, allowing OpenDA to use any BMI compatible model. To circumvent memory shortages which would result from standard applications of the Ensemble Kalman Filter, we have developed a variant that does not need to keep all ensemble members in working memory. At EGU, we will present this variant and how it fits well in HPC environments. An important step in the eWaterCycle project was the coupling between the hydrological and

Semantic Data Integration and Ontology Use within the Global Earth Observation System of Systems (GEOSS) Global Water Cycle Data Integration System

Science.gov (United States)

Pozzi, W.; Fekete, B.; Piasecki, M.; McGuinness, D.; Fox, P.; Lawford, R.; Vorosmarty, C.; Houser, P.; Imam, B.

2008-12-01

The inadequacies of water cycle observations for monitoring long-term changes in the global water system, as well as their feedback into the climate system, poses a major constraint on sustainable development of water resources and improvement of water management practices. Hence, The Group on Earth Observations (GEO) has established Task WA-08-01, "Integration of in situ and satellite data for water cycle monitoring," an integrative initiative combining different types of satellite and in situ observations related to key variables of the water cycle with model outputs for improved accuracy and global coverage. This presentation proposes development of the Rapid, Integrated Monitoring System for the Water Cycle (Global-RIMS)--already employed by the GEO Global Terrestrial Network for Hydrology (GTN-H)--as either one of the main components or linked with the Asian system to constitute the modeling system of GEOSS for water cycle monitoring. We further propose expanded, augmented capability to run multiple grids to embrace some of the heterogeneous methods and formats of the Earth Science, Hydrology, and Hydraulic Engineering communities. Different methodologies are employed by the Earth Science (land surface modeling), the Hydrological (GIS), and the Hydraulic Engineering Communities; with each community employing models that require different input data. Data will be routed as input variables to the models through web services, allowing satellite and in situ data to be integrated together within the modeling framework. Semantic data integration will provide the automation to enable this system to operate in near-real-time. Multiple data collections for ground water, precipitation, soil moisture satellite data, such as SMAP, and lake data will require multiple low level ontologies, and an upper level ontology will permit user-friendly water management knowledge to be synthesized. These ontologies will have to have overlapping terms mapped and linked together. so

World's first ejector cycle for mobile refrigerators to stop global warming

Energy Technology Data Exchange (ETDEWEB)

Takeuchi, Hirotsugu [Denso Corporation, Kariya (Japan); Gyoeroeg, Tibor [DENSO AUTOMOTIVE Deutschland GmbH, Eching (Germany)

2010-07-01

The development of energy-saving technologies is in great demand recently to stop global warming. We are committed to developing the Ejector Cycle as an energy-saving technology for refrigerators and air conditioners. The ejector, which is an energy-saving technological innovation, improves the efficiency of the refrigeration cycle by effectively using the expansion energy that is lost in the conventional vapor-compression cycle, and is applicable to almost all vapor-compression refrigerating air conditioners, thus improving the efficiency of the refrigeration cycle. Concerning the application of the Ejector Cycle in truck-transport refrigerators, we released Ejector Cycle products for large and medium-size freezer trucks, which have been favorably accepted by customers in 2003. Simultaneously we also developed the domestic water supply system using heat pump with natural refrigerant (CO{sub 2}). We developed a new Ejector Cycle, completed in 2007 a cool box which uses the refrigeration cycle of the mobile air-conditioning system to cool drinks and the commercial compact refrigerator. In 2008 a domestic water supply heat pump system using a heat pump with the natural refrigerant CO{sub 2} and the next-generation Ejector Cycle II that substantially improves performance was brought to the market. A new generation of Ejector Cycle is under development which will significantly improve the efficiency of mobile air conditioning systems (orig.)

Long-term global nuclear energy and fuel cycle strategies

International Nuclear Information System (INIS)

Krakowski, R.A.

1997-01-01

The Global Nuclear Vision Project is examining, using scenario building techniques, a range of long-term nuclear energy futures. The exploration and assessment of optimal nuclear fuel-cycle and material strategies is an essential element of the study. To this end, an established global E 3 (energy/economics/environmental) model has been adopted and modified with a simplified, but comprehensive and multi-regional, nuclear energy module. Consistent nuclear energy scenarios are constructed using this multi-regional E 3 model, wherein future demands for nuclear power are projected in price competition with other energy sources under a wide range of long-term demographic (population, workforce size and productivity), economic (price-, population-, and income-determined demand for energy services, price- and population-modified GNP, resource depletion, world-market fossil energy prices), policy (taxes, tariffs, sanctions), and top-level technological (energy intensity and end-use efficiency improvements) drivers. Using the framework provided by the global E 3 model, the impacts of both external and internal drivers are investigated. The ability to connect external and internal drivers through this modeling framework allows the study of impacts and tradeoffs between fossil- versus nuclear-fuel burning, that includes interactions between cost, environmental, proliferation, resource, and policy issues

Long-term global nuclear energy and fuel cycle strategies

Energy Technology Data Exchange (ETDEWEB)

Krakowski, R.A. [Los Alamos National Lab., NM (United States). Technology and Safety Assessment Div.

1997-09-24

The Global Nuclear Vision Project is examining, using scenario building techniques, a range of long-term nuclear energy futures. The exploration and assessment of optimal nuclear fuel-cycle and material strategies is an essential element of the study. To this end, an established global E{sup 3} (energy/economics/environmental) model has been adopted and modified with a simplified, but comprehensive and multi-regional, nuclear energy module. Consistent nuclear energy scenarios are constructed using this multi-regional E{sup 3} model, wherein future demands for nuclear power are projected in price competition with other energy sources under a wide range of long-term demographic (population, workforce size and productivity), economic (price-, population-, and income-determined demand for energy services, price- and population-modified GNP, resource depletion, world-market fossil energy prices), policy (taxes, tariffs, sanctions), and top-level technological (energy intensity and end-use efficiency improvements) drivers. Using the framework provided by the global E{sup 3} model, the impacts of both external and internal drivers are investigated. The ability to connect external and internal drivers through this modeling framework allows the study of impacts and tradeoffs between fossil- versus nuclear-fuel burning, that includes interactions between cost, environmental, proliferation, resource, and policy issues.

The maximum reservoir capacity of soils for persistent organic pollutants: implications for global cycling

International Nuclear Information System (INIS)

Dalla Valle, M.; Jurado, E.; Dachs, J.; Sweetman, A.J.; Jones, K.C.

2005-01-01

The concept of maximum reservoir capacity (MRC), the ratio of the capacities of the surface soil and of the atmospheric mixed layer (AML) to hold chemical under equilibrium conditions, is applied to selected persistent organic pollutants (POPs) in the surface 'skin' (1 mm) of soils. MRC is calculated as a function of soil organic matter (SOM) content and temperature-dependent K OA and mapped globally for selected PCB congeners (PCB-28; -153; -180) and HCB, to identify regions with a higher tendency to retain POPs. It is shown to vary over many orders of magnitude, between compounds, locations and time (seasonally/diurnally). The MRC approach emphasises the very large capacity of soils as a storage compartment for POPs. The theoretical MRC concept is compared to reality and its implications for the global cycling of POPs are discussed. Sharp gradients in soil MRC can exist in mountainous areas and between the land and ocean. Exchanges between oceans and land masses via the atmosphere is likely to be an important driver to the global cycling of these compounds, and net ocean-land transfers could occur in some areas. - Major global terrestrial sinks/stores for POPs are identified and the significance of gradients between them discussed

EDITORIAL: The Earth radiation balance as driver of the global hydrological cycle

Science.gov (United States)

Wild, Martin; Liepert, Beate

2010-06-01

Variations in the intensity of the global hydrological cycle can have far-reaching effects on living conditions on our planet. While climate change discussions often revolve around possible consequences of future temperature changes, the adaptation to changes in the hydrological cycle may pose a bigger challenge to societies and ecosystems. Floods and droughts are already today amongst the most damaging natural hazards, with floods being globally the most significant disaster type in terms of loss of human life (Jonkman 2005). From an economic perspective, changes in the hydrological cycle can impose great pressures and damages on a variety of industrial sectors, such as water management, urban planning, agricultural production and tourism. Despite their obvious environmental and societal importance, our understanding of the causes and magnitude of the variations of the hydrological cycle is still unsatisfactory (e.g., Ramanathan et al 2001, Ohmura and Wild 2002, Allen and Ingram 2002, Allan 2007, Wild et al 2008, Liepert and Previdi 2009). The link between radiation balance and hydrological cycle Globally, precipitation can be approximated by surface evaporation, since the variability of the atmospheric moisture storage is negligible. This is the case because the fluxes are an order of magnitude larger than the atmospheric storage (423 x 1012 m3 year-1 versus 13 x 1012 m3 according to Baumgartner and Reichel (1975)), the latter being determined by temperature (Clausius-Clapeyron). Hence the residence time of evaporated water in the atmosphere is not more than a few days, before it condenses and falls back to Earth in the form of precipitation. Any change in the globally averaged surface evaporation therefore implies an equivalent change in precipitation, and thus in the intensity of the global hydrological cycle. The process of evaporation requires energy, which it obtains from the surface radiation balance (also known as surface net radiation), composed of the

Enhancing atmospheric mercury research in China to improve the current understanding of the global mercury cycle: the need for urgent and closely coordinated efforts.

Science.gov (United States)

Ci, Zhijia; Zhang, Xiaoshan; Wang, Zhangwei

2012-06-05

The current understanding of the global mercury (Hg) cycle remains uncertain because Hg behavior in the environment is very complicated. The special property of Hg causes the atmosphere to be the most important medium for worldwide dispersion and transformation. The source and fate of atmospheric Hg and its interaction with the surface environment are the essential topics in the global Hg cycle. Recent declining measurement trends of Hg in the atmosphere are in apparent conflict with the increasing trends in global anthropogenic Hg emissions. As the single largest country contributor of anthropogenic Hg emission, China's role in the global Hg cycle will become more and more important in the context of the decreasing man-made Hg emission from developed regions. However, much less Hg information in China is available. As a global pollutant which undergoes long-range transport and is persistence in the environment, increasing Hg knowledge in China could not only promote the Hg regulation in this country but also improve the understanding of the fundamental of the global Hg cycle and further push the abatement of this toxin on a global scale. Then the atmospheric Hg research in China may be a breakthrough for improving the current understanding of the global Hg cycle. However, due to the complex behavior of Hg in the atmosphere, a deeper understanding of the atmospheric Hg cycle in China needs greater cooperation across fields.

Top-down constraints on disturbance dynamics in the terrestrial carbon cycle: effects at global and regional scales

Science.gov (United States)

Bloom, A. A.; Exbrayat, J. F.; van der Velde, I.; Peters, W.; Williams, M.

2014-12-01

Large uncertainties preside over terrestrial carbon flux estimates on a global scale. In particular, the strongly coupled dynamics between net ecosystem productivity and disturbance C losses are poorly constrained. To gain an improved understanding of ecosystem C dynamics from regional to global scale, we apply a Markov Chain Monte Carlo based model-data-fusion approach into the CArbon DAta-MOdel fraMework (CARDAMOM). We assimilate MODIS LAI and burned area, plant-trait data, and use the Harmonized World Soil Database (HWSD) and maps of above ground biomass as prior knowledge for initial conditions. We optimize model parameters based on (a) globally spanning observations and (b) ecological and dynamic constraints that force single parameter values and parameter inter-dependencies to be representative of real world processes. We determine the spatial and temporal dynamics of major terrestrial C fluxes and model parameter values on a global scale (GPP = 123 +/- 8 Pg C yr-1 & NEE = -1.8 +/- 2.7 Pg C yr-1). We further show that the incorporation of disturbance fluxes, and accounting for their instantaneous or delayed effect, is of critical importance in constraining global C cycle dynamics, particularly in the tropics. In a higher resolution case study centred on the Amazon Basin we show how fires not only trigger large instantaneous emissions of burned matter, but also how they are responsible for a sustained reduction of up to 50% in plant uptake following the depletion of biomass stocks. The combination of these two fire-induced effects leads to a 1 g C m-2 d-1reduction in the strength of the net terrestrial carbon sink. Through our simulations at regional and global scale, we advocate the need to assimilate disturbance metrics in global terrestrial carbon cycle models to bridge the gap between globally spanning terrestrial carbon cycle data and the full dynamics of the ecosystem C cycle. Disturbances are especially important because their quick occurrence may have

Process modelling and techno-economic analysis of natural gas combined cycle integrated with calcium looping

Directory of Open Access Journals (Sweden)

Erans María

2016-01-01

Full Text Available Calcium looping (CaL is promising for large-scale CO2 capture in the power generation and industrial sectors due to the cheap sorbent used and the relatively low energy penalties achieved with this process. Because of the high operating temperatures the heat utilisation is a major advantage of the process, since a significant amount of power can be generated from it. However, this increases its complexity and capital costs. Therefore, not only the energy efficiency performance is important for these cycles, but also the capital costs must be taken into account, i.e. techno-economic analyses are required in order to determine which parameters and configurations are optimal to enhance technology viability in different integration scenarios. In this study the integration scenarios of CaL cycles and natural gas combined cycles (NGCC are explored. The process models of the NGCC and CaL capture plant are developed to explore the most promising scenarios for NGCC-CaL integration with regards to efficiency penalties. Two scenarios are analysed in detail, and show that the system with heat recovery steam generator (HRSG before and after the capture plant exhibited better performance of 49.1% efficiency compared with that of 45.7% when only one HRSG is located after the capture plant. However, the techno-economic analyses showed that the more energy efficient case, with two HRSGs, implies relatively higher cost of electricity (COE, 44.1€/MWh, when compared to that of the reference plant system (33.1€/MWh. The predicted cost of CO2 avoided for the case with two HRSGS is 29.3 €/ton CO2.

A Time Series Analysis of Global Soil Moisture Data Products for Water Cycle Studies

Science.gov (United States)

Zhan, X.; Yin, J.; Liu, J.; Fang, L.; Hain, C.; Ferraro, R. R.; Weng, F.

2017-12-01

Water is essential for sustaining life on our planet Earth and water cycle is one of the most important processes of out weather and climate system. As one of the major components of the water cycle, soil moisture impacts significantly the other water cycle components (e.g. evapotranspiration, runoff, etc) and the carbon cycle (e.g. plant/crop photosynthesis and respiration). Understanding of soil moisture status and dynamics is crucial for monitoring and predicting the weather, climate, hydrology and ecological processes. Satellite remote sensing has been used for soil moisture observation since the launch of the Scanning Multi-channel Microwave Radiometer (SMMR) on NASA's Nimbus-7 satellite in 1978. Many satellite soil moisture data products have been made available to the science communities and general public. The soil moisture operational product system (SMOPS) of NOAA NESDIS has been operationally providing global soil moisture data products from each of the currently available microwave satellite sensors and their blends. This presentation will provide an update of SMOPS products. The time series of each of these soil moisture data products are analyzed against other data products, such as precipitation and evapotranspiration from other independent data sources such as the North America Land Data Assimilation System (NLDAS). Temporal characteristics of these water cycle components are explored against some historical events, such as the 2010 Russian, 2010 China and 2012 United States droughts, 2015 South Carolina floods, etc. Finally whether a merged global soil moisture data product can be used as a climate data record is evaluated based on the above analyses.

Bacteria in the greenhouse: Modeling the role of oceanic plankton in the global carbon cycle

International Nuclear Information System (INIS)

Ducklow, H.W.; Fasham, M.J.R.

1992-01-01

To plan effectively to deal with the greenhouse effect, a fundamental understanding is needed of the biogeochemical and physical machinery that cycles carbon in the global system; in addition, models are needed of the carbon cycle to project the effects of increasing carbon dioxide. In this chapter, a description is given of efforts to simulate the cycling of carbon and nitrogen in the upper ocean, concentrating on the model's treatment of marine phytoplankton, and what it reveals of their role in the biogeochemical cycling of carbon between the ocean and atmosphere. The focus is on the upper ocean because oceanic uptake appears to regulate the level of carbon dioxide in the atmosphere

The decadal state of the terrestrial carbon cycle : Global retrievals of terrestrial carbon allocation, pools, and residence times

NARCIS (Netherlands)

Bloom, A Anthony; Exbrayat, Jean-François; van der Velde, Ivar R; Feng, Liang; Williams, Mathew

2016-01-01

The terrestrial carbon cycle is currently the least constrained component of the global carbon budget. Large uncertainties stem from a poor understanding of plant carbon allocation, stocks, residence times, and carbon use efficiency. Imposing observational constraints on the terrestrial carbon cycle

How do persistent organic pollutants be coupled with biogeochemical cycles of carbon and nutrients in terrestrial ecosystems under global climate change?

Energy Technology Data Exchange (ETDEWEB)

Teng, Ying [Chinese Academy of Sciences, Nanjing (China). Key Lab. of Soil Environment and Pollution Remediation; Griffith Univ., Nathan, QLD (Australia). Environmetnal Futures Centre and School of Biomolecular and Physical Sciences; Xu, Zhihong; Reverchon, Frederique [Griffith Univ., Nathan, QLD (Australia). Environmetnal Futures Centre and School of Biomolecular and Physical Sciences; Luo, Yongming [Chinese Academy of Sciences, Nanjing (China). Key Lab. of Soil Environment and Pollution Remediation

2012-03-15

Global climate change (GCC), especially global warming, has affected the material cycling (e.g., carbon, nutrients, and organic chemicals) and the energy flows of terrestrial ecosystems. Persistent organic pollutants (POPs) were regarded as anthropogenic organic carbon (OC) source, and be coupled with the natural carbon (C) and nutrient biogeochemical cycling in ecosystems. The objective of this work was to review the current literature and explore potential coupling processes and mechanisms between POPs and biogeochemical cycles of C and nutrients in terrestrial ecosystems induced by global warming. Global warming has caused many physical, chemical, and biological changes in terrestrial ecosystems. POPs environmental fate in these ecosystems is controlled mainly by temperature and biogeochemical processes. Global warming may accelerate the re-emissions and redistribution of POPs among environmental compartments via soil-air exchange. Soil-air exchange is a key process controlling the fate and transportation of POPs and terrestrial ecosystem C at regional and global scales. Soil respiration is one of the largest terrestrial C flux induced by microbe and plant metabolism, which can affect POPs biotransformation in terrestrial ecosystems. Carbon flow through food web structure also may have important consequences for the biomagnification of POPs in the ecosystems and further lead to biodiversity loss induced by climate change and POPs pollution stress. Moreover, the integrated techniques and biological adaptation strategy help to fully explore the coupling mechanisms, functioning and trends of POPs and C and nutrient biogeochemical cycling processes in terrestrial ecosystems. There is increasing evidence that the environmental fate of POPs has been linked with biogeochemical cycles of C and nutrients in terrestrial ecosystems under GCC. However, the relationships between POPs and the biogeochemical cycles of C and nutrients are still not well understood. Further

Modelling cell cycle synchronisation in networks of coupled radial glial cells.

Science.gov (United States)

Barrack, Duncan S; Thul, Rüdiger; Owen, Markus R

2015-07-21

Radial glial cells play a crucial role in the embryonic mammalian brain. Their proliferation is thought to be controlled, in part, by ATP mediated calcium signals. It has been hypothesised that these signals act to locally synchronise cell cycles, so that clusters of cells proliferate together, shedding daughter cells in uniform sheets. In this paper we investigate this cell cycle synchronisation by taking an ordinary differential equation model that couples the dynamics of intracellular calcium and the cell cycle and extend it to populations of cells coupled via extracellular ATP signals. Through bifurcation analysis we show that although ATP mediated calcium release can lead to cell cycle synchronisation, a number of other asynchronous oscillatory solutions including torus solutions dominate the parameter space and cell cycle synchronisation is far from guaranteed. Despite this, numerical results indicate that the transient and not the asymptotic behaviour of the system is important in accounting for cell cycle synchronisation. In particular, quiescent cells can be entrained on to the cell cycle via ATP mediated calcium signals initiated by a driving cell and crucially will cycle in near synchrony with the driving cell for the duration of neurogenesis. This behaviour is highly sensitive to the timing of ATP release, with release at the G1/S phase transition of the cell cycle far more likely to lead to near synchrony than release during mid G1 phase. This result, which suggests that ATP release timing is critical to radial glia cell cycle synchronisation, may help us to understand normal and pathological brain development. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluating the Long-term Water Cycle Trends at a Global-scale using Satellite and Assimilation Datasets

Science.gov (United States)

Kim, H.; Lakshmi, V.

2017-12-01

Global-scale soil moisture and rainfall products retrieved from remotely sensed and assimilation datasets provide an effective way to monitor near surface soil moisture content and precipitation with sub-daily temporal resolution. In the present study, we employed the concept of the stored precipitation fraction Fp(f) in order to examine the long-term water cycle trends at a global-scale. The analysis was done for Fp(f) trends with the various geophysical aspects such as climate zone, land use classifications, amount of vegetation, and soil properties. Furthermore, we compared a global-scale Fp(f) using different microwave-based satellite soil moisture datasets. The Fp(f) is calculated by utilized surface soil moisture dataset from Soil Moisture Active Passive (SMAP), Soil Moisture and Ocean Salinity, Advanced Scatterometer, Advanced Microwave Scanning Radiometer 2, and precipitation information from Global Precipitation Measurement Mission and Global Land Data Assimilation System. Different results from microwave-based soil moisture dataset showed discordant results particularly over arid and highly vegetated regions. The results of this study provide us new insights of the long-term water cycle trends over different land surface areas. Thereby also highlighting the advantages of the recently available GPM and SMAP datasets for the uses in various hydrometeorological applications.

TRMM and Its Connection to the Global Water Cycle

Science.gov (United States)

Kummerow, Christian; Hong, Ye

1999-01-01

The importance of quantitative knowledge of tropical rainfall, its associated latent heating and variability is summarized in the context of the global hydrologic cycle. Much of the tropics is covered by oceans. What land exists, is covered largely by rainforests that are only thinly populated. The only way to adequately measure the global tropical rainfall for climate and general circulation models is from space. The TRMM orbit is inclined 35' leading to good sampling in the tropics and a rapid precession to study the diurnal cycle of precipitation. The precipitation instrument complement consists of the first rain radar to be flown in space (PR), a multi-channel passive microwave sensor (TMI) and a five-channel VIS/IR (VIRS) sensor. The precipitation radar operates at a frequency of 13.6 GHz. The swath width is 220 km, with a horizontal resolution of 4 km and the vertical resolution of 250 in. The minimum detectable signal from the precipitation radar has been measured at 17 dBZ. The TMI instrument is designed similar to the SSM/I with two important changes. The 22.235 GHz water vapor absorption channel of the SSM/I was moved to 21.3 GHz in order to avoid saturation in the tropics and 10.7 GHz V&H polarized channels were added to expand the dynamic range of rainfall estimates. The resolution of the TMI varies from 4.6 km at 85 GHz to 36 km at 10.7 GHz. The visible and infrared sensor (VIRS) measures radiation at 0.63, 1.6, 3.75, 10.8 and 12.0 microns. The spatial resolution of all five VIRS channels is 2 km at nadir. In addition to the three primary rainfall instruments, TRMM will also carry a Lightning Imaging Sensor (LIS) and a Clouds and the Earth's Radiant Energy System (CERES) instrument.

Exogenous Calcium Alleviates Photoinhibition of PSII by Improving the Xanthophyll Cycle in Peanut (Arachis Hypogaea) Leaves during Heat Stress under High Irradiance

Science.gov (United States)

Yang, Sha; Wang, Fang; Guo, Feng; Meng, Jing-Jing; Li, Xin-Guo; Dong, Shu-Ting; Wan, Shu-Bo

2013-01-01

Peanut is one of the calciphilous plants. Calcium (Ca) serves as a ubiquitous central hub in a large number of signaling pathways. The effect of exogenous calcium nitrate [Ca(NO3)2] (6 mM) on the dissipation of excess excitation energy in the photosystem II (PSII) antenna, especially on the level of D1 protein and the xanthophyll cycle in peanut plants under heat (40°C) and high irradiance (HI) (1 200 µmol m−2 s−1) stress were investigated. Compared with the control plants [cultivated in 0 mM Ca(NO3)2 medium], the maximal photochemical efficiency of PSII (Fv/Fm) in Ca2+-treated plants showed a slighter decrease after 5 h of stress, accompanied by higher non-photochemical quenching (NPQ), higher expression of antioxidative genes and less reactive oxygen species (ROS) accumulation. Meanwhile, higher content of D1 protein and higher ratio of (A+Z)/(V+A+Z) were also detected in Ca2+-treated plants under such stress. These results showed that Ca2+ could help protect the peanut photosynthetic system from severe photoinhibition under heat and HI stress by accelerating the repair of D1 protein and improving the de-epoxidation ratio of the xanthophyll cycle. Furthermore, EGTA (a chelant of Ca ion), LaCl3 (a blocker of Ca2+ channel in cytoplasmic membrane), and CPZ [a calmodulin (CaM) antagonist] were used to analyze the effects of Ca2+/CaM on the variation of (A+Z)/(V+A+Z) (%) and the expression of violaxanthin de-epoxidase (VDE). The results indicated that CaM, an important component of the Ca2+ signal transduction pathway, mediated the expression of the VDE gene in the presence of Ca to improve the xanthophyll cycle. PMID:23940721

Exogenous calcium alleviates photoinhibition of PSII by improving the xanthophyll cycle in peanut (Arachis hypogaea leaves during heat stress under high irradiance.

Directory of Open Access Journals (Sweden)

Sha Yang

Full Text Available Peanut is one of the calciphilous plants. Calcium (Ca serves as a ubiquitous central hub in a large number of signaling pathways. The effect of exogenous calcium nitrate [Ca(NO32] (6 mM on the dissipation of excess excitation energy in the photosystem II (PSII antenna, especially on the level of D1 protein and the xanthophyll cycle in peanut plants under heat (40°C and high irradiance (HI (1 200 µmol m(-2 s(-1 stress were investigated. Compared with the control plants [cultivated in 0 mM Ca(NO32 medium], the maximal photochemical efficiency of PSII (Fv/Fm in Ca(2+-treated plants showed a slighter decrease after 5 h of stress, accompanied by higher non-photochemical quenching (NPQ, higher expression of antioxidative genes and less reactive oxygen species (ROS accumulation. Meanwhile, higher content of D1 protein and higher ratio of (A+Z/(V+A+Z were also detected in Ca(2+-treated plants under such stress. These results showed that Ca(2+ could help protect the peanut photosynthetic system from severe photoinhibition under heat and HI stress by accelerating the repair of D1 protein and improving the de-epoxidation ratio of the xanthophyll cycle. Furthermore, EGTA (a chelant of Ca ion, LaCl3 (a blocker of Ca(2+ channel in cytoplasmic membrane, and CPZ [a calmodulin (CaM antagonist] were used to analyze the effects of Ca(2+/CaM on the variation of (A+Z/(V+A+Z (% and the expression of violaxanthin de-epoxidase (VDE. The results indicated that CaM, an important component of the Ca(2+ signal transduction pathway, mediated the expression of the VDE gene in the presence of Ca to improve the xanthophyll cycle.

Earth Without Life: A Systems Model of a Global Abiotic Nitrogen Cycle.

Science.gov (United States)

Laneuville, Matthieu; Kameya, Masafumi; Cleaves, H James

2018-03-20

Nitrogen is the major component of Earth's atmosphere and plays important roles in biochemistry. Biological systems have evolved a variety of mechanisms for fixing and recycling environmental nitrogen sources, which links them tightly with terrestrial nitrogen reservoirs. However, prior to the emergence of biology, all nitrogen cycling was abiological, and this cycling may have set the stage for the origin of life. It is of interest to understand how nitrogen cycling would proceed on terrestrial planets with comparable geodynamic activity to Earth, but on which life does not arise. We constructed a kinetic mass-flux model of nitrogen cycling in its various major chemical forms (e.g., N 2 , reduced (NH x ) and oxidized (NO x ) species) between major planetary reservoirs (the atmosphere, oceans, crust, and mantle) and included inputs from space. The total amount of nitrogen species that can be accommodated in each reservoir, and the ways in which fluxes and reservoir sizes may have changed over time in the absence of biology, are explored. Given a partition of volcanism between arc and hotspot types similar to the modern ones, our global nitrogen cycling model predicts a significant increase in oceanic nitrogen content over time, mostly as NH x , while atmospheric N 2 content could be lower than today. The transport timescales between reservoirs are fast compared to the evolution of the environment; thus atmospheric composition is tightly linked to surface and interior processes. Key Words: Nitrogen cycle-Abiotic-Planetology-Astrobiology. Astrobiology 18, xxx-xxx.

Andreae is New Editor of Global Biogeochemical Cycles

Science.gov (United States)

Andreae, Meinrat O.

2004-10-01

As the incoming editor of Global Biogeochemical Cycles, I would like to introduce myself and my ideas for the journal to Eos readers and to current and potential GBC authors. I've had a somewhat ``roaming'' scientific evolution, coming from ``straight'' chemistry through hard-rock geochemistry to chemical oceanography, the field in which I did my Ph.D. I taught marine chemistry at Florida State University for a number of years, and developed an interest in ocean/atmosphere interactions and atmospheric chemistry. In 1987 I took on my present job at the Max Planck Institute for Chemistry, in Mainz, Germany, and, after leaving the seacoast, my interests shifted to interactions between the terrestrial biosphere and atmosphere, including the role of vegetation fires. My present focus is on the role of biogenic aerosols and biomass smoke in regulating cloud properties and influencing climate.

The Antarctic Centennial Oscillation: A Natural Paleoclimate Cycle in the Southern Hemisphere That Influences Global Temperature

Directory of Open Access Journals (Sweden)

W. Jackson Davis

2018-01-01

Full Text Available We report a previously-unexplored natural temperature cycle recorded in ice cores from Antarctica—the Antarctic Centennial Oscillation (ACO—that has oscillated for at least the last 226 millennia. Here we document the properties of the ACO and provide an initial assessment of its role in global climate. We analyzed open-source databases of stable isotopes of oxygen and hydrogen as proxies for paleo-temperatures. We find that centennial-scale spectral peaks from temperature-proxy records at Vostok over the last 10,000 years occur at the same frequencies (±2.4% in three other paleoclimate records from drill sites distributed widely across the East Antarctic Plateau (EAP, and >98% of individual ACOs evaluated at Vostok match 1:1 with homologous cycles at the other three EAP drill sites and conversely. Identified ACOs summate with millennial periodicity to form the Antarctic Isotope Maxima (AIMs known to precede Dansgaard-Oeschger (D-O oscillations recorded in Greenland ice cores. Homologous ACOs recorded at the four EAP drill sites during the last glacial maximum appeared first at lower elevations nearest the ocean and centuries later on the high EAP, with latencies that exceed dating uncertainty >30-fold. ACO homologs at different drill sites became synchronous, however, during the warmer Holocene. Comparative spectral analysis suggests that the millennial-scale AIM cycle declined in period from 1500 to 800 years over the last 70 millennia. Similarly, over the last 226 millennia ACO repetition period (mean 352 years declined by half while amplitude (mean 0.67 °C approximately doubled. The period and amplitude of ACOs oscillate in phase with glacial cycles and related surface insolation associated with planetary orbital forces. We conclude that the ACO: encompasses at least the EAP; is the proximate source of D-O oscillations in the Northern Hemisphere; therefore affects global temperature; propagates with increased velocity as temperature

Global guidance on environmental life cycle impact assessment indicators: impacts of climate change, fine particulate matter formation, water consumption and land use

DEFF Research Database (Denmark)

Jolliet, Olivier; Antón, Assumpció; Boulay, Anne-Marie

2018-01-01

of water consumption on human health assesses the DALYs from malnutrition caused by lack of water for irrigated food production. Land use impacts: CFs representing global potential species loss from land use are proposed as interim recommendation suitable to assess biodiversity loss due to land use......Purpose: Guidance is needed on best-suited indicators to quantify and monitor the man-made impacts on human health, biodiversity and resources. Therefore, the UNEP-SETAC Life Cycle Initiative initiated a global consensus process to agree on an updated overall life cycle impact assessment (LCIA...... are recommended: (a) The global warming potential 100 years (GWP 100) represents shorter term impacts associated with rate of change and adaptation capacity, and (b) the global temperature change potential 100 years (GTP 100) characterizes the century-scale long term impacts, both including climate-carbon cycle...

Oxalate secretion by ectomycorrhizal Paxillus involutus is mineral-specific and controls calcium weathering from minerals

Science.gov (United States)

Schmalenberger, A.; Duran, A. L.; Bray, A. W.; Bridge, J.; Bonneville, S.; Benning, L. G.; Romero-Gonzalez, M. E.; Leake, J. R.; Banwart, S. A.

2015-01-01

Trees and their associated rhizosphere organisms play a major role in mineral weathering driving calcium fluxes from the continents to the oceans that ultimately control long-term atmospheric CO2 and climate through the geochemical carbon cycle. Photosynthate allocation to tree roots and their mycorrhizal fungi is hypothesized to fuel the active secretion of protons and organic chelators that enhance calcium dissolution at fungal-mineral interfaces. This was tested using 14CO2 supplied to shoots of Pinus sylvestris ectomycorrhizal with the widespread fungus Paxillus involutus in monoxenic microcosms, revealing preferential allocation by the fungus of plant photoassimilate to weather grains of limestone and silicates each with a combined calcium and magnesium content of over 10 wt.%. Hyphae had acidic surfaces and linear accumulation of weathered calcium with secreted oxalate, increasing significantly in sequence: quartz, granite mineral-specific oxalate exudation in ectomycorrhizal weathering to dissolve calcium bearing minerals, thus contributing to the geochemical carbon cycle. PMID:26197714

Calcium-deficiency assessment and biomarker identification by an integrated urinary metabonomics analysis

Science.gov (United States)

2013-01-01

Background Calcium deficiency is a global public-health problem. Although the initial stage of calcium deficiency can lead to metabolic alterations or potential pathological changes, calcium deficiency is difficult to diagnose accurately. Moreover, the details of the molecular mechanism of calcium deficiency remain somewhat elusive. To accurately assess and provide appropriate nutritional intervention, we carried out a global analysis of metabolic alterations in response to calcium deficiency. Methods The metabolic alterations associated with calcium deficiency were first investigated in a rat model, using urinary metabonomics based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry and multivariate statistical analysis. Correlations between dietary calcium intake and the biomarkers identified from the rat model were further analyzed to confirm the potential application of these biomarkers in humans. Results Urinary metabolic-profiling analysis could preliminarily distinguish between calcium-deficient and non-deficient rats after a 2-week low-calcium diet. We established an integrated metabonomics strategy for identifying reliable biomarkers of calcium deficiency using a time-course analysis of discriminating metabolites in a low-calcium diet experiment, repeating the low-calcium diet experiment and performing a calcium-supplement experiment. In total, 27 biomarkers were identified, including glycine, oxoglutaric acid, pyrophosphoric acid, sebacic acid, pseudouridine, indoxyl sulfate, taurine, and phenylacetylglycine. The integrated urinary metabonomics analysis, which combined biomarkers with regular trends of change (types A, B, and C), could accurately assess calcium-deficient rats at different stages and clarify the dynamic pathophysiological changes and molecular mechanism of calcium deficiency in detail. Significant correlations between calcium intake and two biomarkers, pseudouridine (Pearson

Updates on Modeling the Water Cycle with the NASA Ames Mars Global Climate Model

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Kahre, M. A.; Haberle, R. M.; Hollingsworth, J. L.; Montmessin, F.; Brecht, A. S.; Urata, R.; Klassen, D. R.; Wolff, M. J.

2017-01-01

Global Circulation Models (GCMs) have made steady progress in simulating the current Mars water cycle. It is now widely recognized that clouds are a critical component that can significantly affect the nature of the simulated water cycle. Two processes in particular are key to implementing clouds in a GCM: the microphysical processes of formation and dissipation, and their radiative effects on heating/ cooling rates. Together, these processes alter the thermal structure, change the dynamics, and regulate inter-hemispheric transport. We have made considerable progress representing these processes in the NASA Ames GCM, particularly in the presence of radiatively active water ice clouds. We present the current state of our group's water cycle modeling efforts, show results from selected simulations, highlight some of the issues, and discuss avenues for further investigation.­

The impact of organochlorines cycling in the cryosphere on their global distribution and fate – 1. Sea ice

International Nuclear Information System (INIS)

Guglielmo, Francesca; Stemmler, Irene; Lammel, Gerhard

2012-01-01

Global fate and transport of γ-HCH and DDT was studied using a global multicompartment chemistry-transport model, MPI-MCTM, with and without a dynamic sea ice compartment. The MPI-MCTM is based on coupled ocean and atmosphere general circulation models. Sea ice hosts 7–9% of the burden of the surface ocean. Without cycling in sea ice the geographic distributions are shifted from land to sea. This shift of burdens exceeds the sea ice burden by a factor of ≈8 for γ-HCH and by a factor of ≈15 for DDT. As regional scale seasonal sea ice melting may double surface ocean contamination, a neglect of cycling in sea ice (in an otherwise unchanged model climate) would underestimate ocean exposure in high latitudes. Furthermore, it would lead to overestimates of the residence times in ocean by 40% and 33% and of the total environmental residence times, τ overall , of γ-HCH and DDT by 1.6% and 0.6%, respectively. - Highlights: ► Sea ice hosts 7–9% of the burden of γ-HCH and DDT in the surface ocean. ► Without cycling in sea ice the distributions are shifted from land to sea. ► A neglect of cycling in sea ice would underestimate ocean exposure in high latitudes. ► Persistence of γ-HCH and DDT expected enhanced in climate without sea ice. - The inclusion of cycling in sea ice is found relevant for POPs fate and transport modelling on the global scale.

Diazotroph-Bacterial Community Structure of Root Nodules Account for Two-Fold Differences in Plant Growth: Consequences for Global Biogeochemical Cycles

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Williams, M. A.

2016-12-01

The bacterial communities that inhabit and function as mutualists in the nodules of soybean, a major worldwide crop, are a fundamental determinant of plant growth and global nitrogen and carbon cycles. Unfertilized soybean can derive up to 90% of its nitrogen through bacterial-driven diazotrophy. It was the goal of the research in this study to assess whether different bacterial taxa (e.g. Bradyrhizobia spp.) differ in their soybean growth supportive role, which could then feedback to alter global biogeochemical cycling. Using 16S rRNA and NifH genes, nodule bacterial communities were shown to vary across 9 different cultivars of soybean, and that the variation between cultivars were highly correlated to plant yield (97 to 188 bu/Ha) and nitrogen. The relative abundances of gene sequences associated with the closest taxonomic match (NCBI), indicated that several taxa were (r= 0.76) negatively (e.g. Bradyrhizobium sp Ec3.3) or (r= 0.84) positively (e.g. Bradyrhizobium elkanii WSM 2783) correlated with plant yield. Other non-Rhizobiaceae taxa, such as Rhodopseudomonas spp. were also prevalent and correlated with plant yield. Soybeans and other leguminous crops will become increasingly important part of world food production, soil fertility and global biogeochemical cycles with rising population and food demand. The study demonstrates the importance of plant-microbial feedbacks driving plant growth but also ramifications for global cycling of nitrogen and carbon.

The global warming potential of building materials : An application of life cycle analysis in Nepal

NARCIS (Netherlands)

Bhochhibhoya, Silu; Zanetti, Michela; Pierobon, Francesca; Gatto, Paola; Maskey, Ramesh Kumar; Cavalli, Raffaele

2017-01-01

This paper analyzes the global-warming potential of materials used to construct the walls of 3 building types - traditional, semimodern, and modern - in Sagarmatha National Park and Buffer Zone in Nepal, using the life-cycle assessment approach. Traditional buildings use local materials, mainly wood

Cross talk among calcium, hydrogen peroxide, and nitric oxide and activation of gene expression involving calmodulins and calcium-dependent protein kinases in Ulva compressa exposed to copper excess.

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González, Alberto; Cabrera, M de Los Ángeles; Henríquez, M Josefa; Contreras, Rodrigo A; Morales, Bernardo; Moenne, Alejandra

2012-03-01

To analyze the copper-induced cross talk among calcium, nitric oxide (NO), and hydrogen peroxide (H(2)O(2)) and the calcium-dependent activation of gene expression, the marine alga Ulva compressa was treated with the inhibitors of calcium channels, ned-19, ryanodine, and xestospongin C, of chloroplasts and mitochondrial electron transport chains, 3-(3,4-dichlorophenyl)-1,1-dimethylurea and antimycin A, of pyruvate dehydrogenase, moniliformin, of calmodulins, N-(6-aminohexyl)-5-chloro-1-naphtalene sulfonamide, and of calcium-dependent protein kinases, staurosporine, as well as with the scavengers of NO, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, and of H(2)O(2), ascorbate, and exposed to a sublethal concentration of copper (10 μm) for 24 h. The level of NO increased at 2 and 12 h. The first peak was inhibited by ned-19 and 3-(2,3-dichlorophenyl)-1,1-dimethylurea and the second peak by ned-19 and antimycin A, indicating that NO synthesis is dependent on calcium release and occurs in organelles. The level of H(2)O(2) increased at 2, 3, and 12 h and was inhibited by ned-19, ryanodine, xestospongin C, and moniliformin, indicating that H(2)O(2) accumulation is dependent on calcium release and Krebs cycle activity. In addition, pyruvate dehydrogenase, 2-oxoxglutarate dehydrogenase, and isocitrate dehydrogenase activities of the Krebs cycle increased at 2, 3, 12, and/or 14 h, and these increases were inhibited in vitro by EGTA, a calcium chelating agent. Calcium release at 2, 3, and 12 h was inhibited by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and ascorbate, indicating activation by NO and H(2)O(2). In addition, the level of antioxidant protein gene transcripts decreased with N-(6-aminohexyl)-5-chloro-1-naphtalene sulfonamide and staurosporine. Thus, there is a copper-induced cross talk among calcium, H(2)O(2), and NO and a calcium-dependent activation of gene expression involving calmodulins and calcium-dependent protein

NASA Contributions to Improve Understanding of Extreme Events in the Global Energy and Water Cycle

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Lapenta, William M.

2008-01-01

The U.S. Climate Change Science Program (CCSP) has established the water cycle goals of the Nation's climate change program. Accomplishing these goals will require, in part, an accurate accounting of the key reservoirs and fluxes associated with the global water and energy cycle, including their spatial and temporal variability. through integration of all necessary observations and research tools, To this end, in conjunction with NASA's Earth science research strategy, the overarching long-term NASA Energy and Water Cycle Study (NEWS) grand challenge can he summarized as documenting and enabling improved, observationally based, predictions of water and energy cycle consequences of Earth system variability and change. This challenge requires documenting and predicting trends in the rate of the Earth's water and energy cycling that corresponds to climate change and changes in the frequency and intensity of naturally occurring related meteorological and hydrologic events, which may vary as climate may vary in the future. The cycling of water and energy has obvious and significant implications for the health and prosperity of our society. The importance of documenting and predicting water and energy cycle variations and extremes is necessary to accomplish this benefit to society.

Soils and Global Change in the Carbon Cycle over Geological Time

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Retallack, G. J.

2003-12-01

Soils play an important role in the carbon cycle as the nutrition of photosynthesized biomass. Nitrogen fixed by microbes from air is a limiting nutrient for ecosystems within the first flush of ecological succession of new ground, and sulfur can limit some components of wetland ecosystems. But over the long term, the limiting soil nutrient is phosphorus extracted by weathering from minerals such as apatite (Vitousek et al., 1997a; Chadwick et al., 1999). Life has an especially voracious appetite for common alkali (Na+ and K+) and alkaline earth (Ca2+ and Mg2+) cations, supplied by hydrolytic weathering, which is in turn amplified by biological acidification (Schwartzmann and Volk, 1991; see Chapter 5.06). These mineral nutrients fuel photosynthetic fixation and chemical reduction of atmospheric CO2 into plants and plantlike microbes, which are at the base of the food chain. Plants and photosynthetic microbes are consumed and oxidized by animals, fungi, and other respiring microbes, which release CO2, methane, and water vapor to the air. These greenhouse gases absorb solar radiation more effectively than atmospheric oxygen and nitrogen, and are important regulators of planetary temperature and albedo (Kasting, 1992). Variations in solar insolation ( Kasting, 1992), mountainous topography ( Raymo and Ruddiman, 1992), and ocean currents ( Ramstein et al., 1997) also play a role in climate, but this review focuses on the carbon cycle. The carbon cycle is discussed in detail in Volume 8 of this Treatise.The greenhouse model for global paleoclimate has proven remarkably robust (Retallack, 2002), despite new challenges ( Veizer et al., 2000). The balance of producers and consumers is one of a number of controls on atmospheric greenhouse gas balance, because CO2 is added to the air from fumaroles, volcanic eruptions, and other forms of mantle degassing (Holland, 1984). Carbon dioxide is also consumed by burial as carbonate and organic matter within limestones and other

Iron control on global productivity: an efficient inverse model of the ocean's coupled phosphate and iron cycles.

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Pasquier, B.; Holzer, M.; Frants, M.

2016-02-01

We construct a data-constrained mechanistic inverse model of the ocean's coupled phosphorus and iron cycles. The nutrient cycling is embedded in a data-assimilated steady global circulation. Biological nutrient uptake is parameterized in terms of nutrient, light, and temperature limitations on growth for two classes of phytoplankton that are not transported explicitly. A matrix formulation of the discretized nutrient tracer equations allows for efficient numerical solutions, which facilitates the objective optimization of the key biogeochemical parameters. The optimization minimizes the misfit between the modelled and observed nutrient fields of the current climate. We systematically assess the nonlinear response of the biological pump to changes in the aeolian iron supply for a variety of scenarios. Specifically, Green-function techniques are employed to quantify in detail the pathways and timescales with which those perturbations are propagated throughout the world oceans, determining the global teleconnections that mediate the response of the global ocean ecosystem. We confirm previous findings from idealized studies that increased iron fertilization decreases biological production in the subtropical gyres and we quantify the counterintuitive and asymmetric response of global productivity to increases and decreases in the aeolian iron supply.

Impact of changes in river fluxes of silica on the global marine silicon cycle: a model comparison

Directory of Open Access Journals (Sweden)

C. Y. Bernard

2010-02-01

Full Text Available The availability of dissolved silica (Si in the ocean provides a major control on the growth of siliceous phytoplankton. Diatoms in particular account for a large proportion of oceanic primary production. The original source of the silica is rock weathering, followed by transport of dissolved and biogenic silica to the coastal zone. This model study aims at assessing the sensitivity of the global marine silicon cycle to variations in the river input of silica on timescales ranging from several centuries to millennia. We compare the performance of a box model for the marine silicon cycle to that of a global biogeochemical ocean general circulation model (HAMOCC2 and 5. Results indicate that the average global ocean response to changes in river input of silica is comparable in the models on time scales up to 150 kyrs. While the trends in export production and opal burial are the same, the box model shows a delayed response to the imposed perturbations compared to the general circulation model. Results of both models confirm the important role of the continental margins as a sink for silica at the global scale. Our work also demonstrates that the effects of changes in riverine dissolved silica on ocean biogeochemistry depend on the availability of the other nutrients such as nitrogen, phosphorus and iron. The model results suggest that the effects of reduced silica inputs due to river damming are particularly pronounced in the Gulf of Bengal, Gulf of Mexico and the Amazon plume where they negatively affect opal production. While general circulation models are indispensable when assessing the spatial variation in opal export production and biogenic Si burial in the ocean, this study demonstrates that box models provide a good alternative when studying the average global ocean response to perturbations of the oceanic silica cycle (especially on longer time scales.

The functions of store-operated calcium channels.

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Putney, James W; Steinckwich-Besançon, Natacha; Numaga-Tomita, Takuro; Davis, Felicity M; Desai, Pooja N; D'Agostin, Diane M; Wu, Shilan; Bird, Gary S

2017-06-01

Store-operated calcium channels provide calcium signals to the cytoplasm of a wide variety of cell types. The basic components of this signaling mechanism include a mechanism for discharging Ca 2+ stores (commonly but not exclusively phospholipase C and inositol 1,4,5-trisphosphate), a sensor in the endoplasmic reticulum that also serves as an activator of the plasma membrane channel (STIM1 and STIM2), and the store-operated channel (Orai1, 2 or 3). The advent of mice genetically altered to reduce store-operated calcium entry globally or in specific cell types has provided important tools to understand the functions of these widely encountered channels in specific and clinically important physiological systems. This review briefly discusses the history and cellular properties of store-operated calcium channels, and summarizes selected studies of their physiological functions in specific physiological or pathological contexts. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech. Published by Elsevier B.V.

Evaluation of calcium alginate gel as electrode material for alternating current iontophoresis of lidocaine using excised rat skin.

Science.gov (United States)

Ebisawa, Tomoko; Nakajima, Atsushi; Haida, Haruka; Wakita, Ryo; Ando, Shizuka; Yoshioka, Tomohiko; Ikoma, Toshiyuki; Tanaka, Junzo; Fukayama, Haruhisa

2014-06-27

Iontophoresis (IOP) is a noninvasive method of delivering medication transcutaneously through the skin. The electrodes used in this method should tightly fit to rough and irregular surfaces and be biologically safe, easy to handle and prepare, and cost-effective. To satisfy these requirements, calcium alginate gel can be a candidate electrode for IOP. Using calcium alginate gel electrodes, we examined whether lidocaine can be effectively transported across an excised rat skin by squarewave alternating current (AC) application. A squarewave AC with either a 70% or 80% duty cycle was continuously applied to 0.5% calcium alginate gel electrodes containing 10% lidocaine at 10 V and 1 kHz for 60 min. Lidocaine concentration was measured using a spectrophotometer and the temperature of the gel was determined. The lidocaine concentrations for AC-IOP at the 70% and 80% duty cycles were significantly higher than that without AC-IOP. Furthermore, the group with the 80% duty cycle showed higher lidocaine concentrations than the group with the 70% duty cycle. The temperatures of all the groups were lower than 28 °C throughout the procedure. In conclusion, the calcium alginate gel can be used as a possible matrix for IOP electrodes.

Calcium paradox and calcium entry blockers

NARCIS (Netherlands)

Ruigrok, T.J.C.; Slade, A.M.; Nayler, W.G.; Meijler, F.L.

1984-01-01

Reperfusion of isolated hearts with calcium-containing solution after a short period of calcium-free perfusion results in irreversible cell damage (calcium paradox). This phenomenon is characterized by an excessive influx of calcium into the cells, the rapid onset of myocardial contracture,

Tropical rainforests dominate multi-decadal variability of the global carbon cycle

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Zhang, X.; Wang, Y. P.; Peng, S.; Rayner, P. J.; Silver, J.; Ciais, P.; Piao, S.; Zhu, Z.; Lu, X.; Zheng, X.

2017-12-01

Recent studies find that inter-annual variability of global atmosphere-to-land CO2 uptake (NBP) is dominated by semi-arid ecosystems. However, the NBP variations at decadal to multi-decadal timescales are still not known. By developing a basic theory for the role of net primary production (NPP) and heterotrophic respiration (Rh) on NBP and applying it to 100-year simulations of terrestrial ecosystem models forced by observational climate, we find that tropical rainforests dominate the multi-decadal variability of global NBP (48%) rather than the semi-arid lands (35%). The NBP variation at inter-annual timescales is almost 90% contributed by NPP, but across longer timescales is progressively controlled by Rh that constitutes the response from the NPP-derived soil carbon input (40%) and the response of soil carbon turnover rates to climate variability (60%). The NBP variations of tropical rainforests is modulated by the ENSO and the PDO through their significant influences on temperature and precipitation at timescales of 2.5-7 and 25-50 years, respectively. This study highlights the importance of tropical rainforests on the multi-decadal variability of global carbon cycle, suggesting that we need to carefully differentiate the effect of NBP long-term fluctuations associated with ocean-related climate modes on the long-term trend in land sink.

Glass vs. Plastic: Life Cycle Assessment of Extra-Virgin Olive Oil Bottles across Global Supply Chains

Directory of Open Access Journals (Sweden)

Riccardo Accorsi

2015-03-01

Full Text Available The environmental impacts of global food supply chains are growing with the need for their measurement and management. This paper explores the operations of a global supply chain for extra-virgin olive oil (EVOO according to a life cycle assessment (LCA methodology. The LCA assessment methodology is applied to determine the environmental impact categories associated with the bottled EVOO life cycle, focusing on packaging decisions. The proposed analysis identifies the greatest environmental stressors of the EVOO supply chain, thereby supporting strategic and operative decisions toward more efficient and environmentally-friendly operations management and packaging choices. This paper quantifies the environmental categories of the impacts of global warming potential, ozone layer depletion, non-renewable energy use, acidification, eutrophication and photochemical smog, for the observed EVOO supply chain, given alternative packaging configurations, i.e., a glass bottle vs. a plastic bottle. The observed system includes the supply of EVOO, the EVOO processing and bottling, the supply of packaging, the distribution of final products to customers, the end-of-life (EOL treatments regarding the management, recycling and the disposal of waste across a global supply chain. The findings from the LCA highlight the potential of PET bottles in reducing the environmental impact of EVOO supply chains and identifies hotspots of discussion for policy-makers, EVOO producers and consumers.

Lagged life cycle structures for food products: Their role in global marketing, their determinants and some problems in their estimation

DEFF Research Database (Denmark)

Baadsgaard, Allan; Gede, Mads Peter; Grunert, Klaus G.

cycles for different product categories may be lagged (type II lag) because changes in economic and other factors will result in demands for different products. Identifying lagged life cycle structures major importance in global marketing of food products. The problems in arriving at such estimates...

A probabilistic assessment of calcium carbonate export and dissolution in the modern ocean

Science.gov (United States)

Battaglia, Gianna; Steinacher, Marco; Joos, Fortunat

2016-05-01

The marine cycle of calcium carbonate (CaCO3) is an important element of the carbon cycle and co-governs the distribution of carbon and alkalinity within the ocean. However, CaCO3 export fluxes and mechanisms governing CaCO3 dissolution are highly uncertain. We present an observationally constrained, probabilistic assessment of the global and regional CaCO3 budgets. Parameters governing pelagic CaCO3 export fluxes and dissolution rates are sampled using a Monte Carlo scheme to construct a 1000-member ensemble with the Bern3D ocean model. Ensemble results are constrained by comparing simulated and observation-based fields of excess dissolved calcium carbonate (TA*). The minerals calcite and aragonite are modelled explicitly and ocean-sediment fluxes are considered. For local dissolution rates, either a strong or a weak dependency on CaCO3 saturation is assumed. In addition, there is the option to have saturation-independent dissolution above the saturation horizon. The median (and 68 % confidence interval) of the constrained model ensemble for global biogenic CaCO3 export is 0.90 (0.72-1.05) Gt C yr-1, that is within the lower half of previously published estimates (0.4-1.8 Gt C yr-1). The spatial pattern of CaCO3 export is broadly consistent with earlier assessments. Export is large in the Southern Ocean, the tropical Indo-Pacific, the northern Pacific and relatively small in the Atlantic. The constrained results are robust across a range of diapycnal mixing coefficients and, thus, ocean circulation strengths. Modelled ocean circulation and transport timescales for the different set-ups were further evaluated with CFC11 and radiocarbon observations. Parameters and mechanisms governing dissolution are hardly constrained by either the TA* data or the current compilation of CaCO3 flux measurements such that model realisations with and without saturation-dependent dissolution achieve skill. We suggest applying saturation-independent dissolution rates in Earth system

Effects of dietary bread crust Maillard reaction products on calcium and bone metabolism in rats.

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Roncero-Ramos, Irene; Delgado-Andrade, Cristina; Haro, Ana; Ruiz-Roca, Beatriz; Morales, Francisco J; Navarro, María Pilar

2013-06-01

Maillard reaction products (MRP) consumption has been related with the development of bone degenerative disorders, probably linked to changes in calcium metabolism. We aimed to investigate the effects of MRP intake from bread crust on calcium balance and its distribution, and bone metabolism. During 88 days, rats were fed control diet or diets containing bread crust as source of MRP, or its soluble high molecular weight, soluble low molecular weight or insoluble fractions (bread crust, HMW, LMW and insoluble diets, respectively). In the final week, a calcium balance was performed, then animals were sacrified and some organs removed to analyse calcium levels. A second balance was carried out throughout the experimental period to calculate global calcium retention. Biochemical parameters and bone metabolism markers were measured in serum or urine. Global calcium bioavailability was unmodified by consumption of bread crust or its isolate fractions, corroborating the previously described low affinity of MRP to bind calcium. Despite this, a higher calcium concentration was found in femur due to smaller bones having a lower relative density. The isolate consumption of the fractions altered some bone markers, reflecting a situation of increased bone resorption or higher turnover; this did not take place in the animals fed the bread crust diet. Thus, the bread crust intake does not affect negatively calcium bioavailability and bone metabolism.

A New Global LAI Product and Its Use for Terrestrial Carbon Cycle Estimation

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Chen, J. M.; Liu, R.; Ju, W.; Liu, Y.

2014-12-01

For improving the estimation of the spatio-temporal dynamics of the terrestrial carbon cycle, a new time series of the leaf area index (LAI) is generated for the global land surface at 8 km resolution from 1981 to 2012 by combining AVHRR and MODIS satellite data. This product differs from existing LAI products in the following two aspects: (1) the non-random spatial distribution of leaves with the canopy is considered, and (2) the seasonal variation of the vegetation background is included. The non-randomness of the leaf spatial distribution in the canopy is considered using the second vegetation structural parameter named clumping index (CI), which quantifies the deviation of the leaf spatial distribution from the random case. Using the MODIS Bidirectional Reflectance Distribution Function product, a global map of CI is produced at 500 m resolution. In our LAI algorithm, CI is used to convert the effective LAI obtained from mono-angle remote sensing into the true LAI, otherwise LAI would be considerably underestimated. The vegetation background is soil in crop, grass and shrub but includes soil, grass, moss, and litter in forests. Through processing a large volume of MISR data from 2000 to 2010, monthly red and near-infrared reflectances of the vegetation background is mapped globally at 1 km resolution. This new LAI product has been validated extensively using ground-based LAI measurements distributed globally. In carbon cycle modeling, the use of CI in addition to LAI allows for accurate separation of sunlit and shaded leaves as an important step in terrestrial photosynthesis and respiration modeling. Carbon flux measurements over 100 sites over the globe are used to validate an ecosystem model named Boreal Ecosystem Productivity Simulator (BEPS). The validated model is run globally at 8 km resolution for the period from 1981 to 2012 using the LAI product and other spatial datasets. The modeled results suggest that changes in vegetation structure as quantified

Artificial oocyte activation with calcium ionophore for frozen sperm cycles.

Science.gov (United States)

Karabulut, Seda; Aksünger, Özlem; Ata, Can; Sağıroglu, Yusuf; Keskin, İlknur

2018-04-05

Fertilization problems are the major problems that may be faced in 30-55% of the patients during an intracytoplasmic sperm injection (ICSI) cycle. A successful oocyte activation depends on factors related to both sperm and oocyte, and one of the important factors that mediates the process is Ca 2+ concentration within the oocyte. Artificial oocyte activation (AOA) is a method used for fertilization problems that commonly involve the usage of Ca 2+ ionophores and is usually used in problems such as total fertilization failure (TFF) and globozoospermia. The aim of the present study was to investigate possible effects of AOA for different groups of patients with fertilization failure. Four groups of patients (previous TFF, low oocyte number, severe sperm quality, and frozen sperm (FS) group) that underwent ICSI with AOA were included in the study. All groups had similar control groups with same indications except TFF, where AOA was not performed. Fertilization rates were significantly higher in the TFF group than those observed in other AOA groups. Fertilization rates and quality of embryos observed in the remaining AOA groups were higher than those of the controls, which were statistically insignificant. Prgenancy rates were higher in all AOA groups compared to the controls, although the differences were significant in FS group only. Quality of embryos and pregnancy rates were lower in the TFF group compared to the remaining AOA groups indicating possible concomitant problems. Fertilization rates, quality of embryos and pregnancy rates seemed to be increased in all indication groups suggesting that not only TFF patients but also a wide variety of patients with different indications may benefit from AOA. ICSI: Intracytoplasmic sperm injection; ARTs: Assisted reproductive techniques; Ca: Calcium; AOA: Artificial oocyte activation; TFF: Total fertilization failures; OAT: Oligoasthenoteratozoospemia; IVF: In vitro fertilization; SOAT: Severe OAT; LON: Low ooctye number

A model of propagating calcium-induced calcium release mediated by calcium diffusion

NARCIS (Netherlands)

Backx, P. H.; de Tombe, P. P.; van Deen, J. H.; Mulder, B. J.; ter Keurs, H. E.

1989-01-01

The effect of sudden local fluctuations of the free sarcoplasmic [Ca++]i in cardiac cells on calcium release and calcium uptake by the sarcoplasmic reticulum (SR) was calculated with the aid of a simplified model of SR calcium handling. The model was used to evaluate whether propagation of calcium

Development of a system emulating the global carbon cycle in Earth system models

Science.gov (United States)

Tachiiri, K.; Hargreaves, J. C.; Annan, J. D.; Oka, A.; Abe-Ouchi, A.; Kawamiya, M.

2010-08-01

Recent studies have indicated that the uncertainty in the global carbon cycle may have a significant impact on the climate. Since state of the art models are too computationally expensive for it to be possible to explore their parametric uncertainty in anything approaching a comprehensive fashion, we have developed a simplified system for investigating this problem. By combining the strong points of general circulation models (GCMs), which contain detailed and complex processes, and Earth system models of intermediate complexity (EMICs), which are quick and capable of large ensembles, we have developed a loosely coupled model (LCM) which can represent the outputs of a GCM-based Earth system model, using much smaller computational resources. We address the problem of relatively poor representation of precipitation within our EMIC, which prevents us from directly coupling it to a vegetation model, by coupling it to a precomputed transient simulation using a full GCM. The LCM consists of three components: an EMIC (MIROC-lite) which consists of a 2-D energy balance atmosphere coupled to a low resolution 3-D GCM ocean (COCO) including an ocean carbon cycle (an NPZD-type marine ecosystem model); a state of the art vegetation model (Sim-CYCLE); and a database of daily temperature, precipitation, and other necessary climatic fields to drive Sim-CYCLE from a precomputed transient simulation from a state of the art AOGCM. The transient warming of the climate system is calculated from MIROC-lite, with the global temperature anomaly used to select the most appropriate annual climatic field from the pre-computed AOGCM simulation which, in this case, is a 1% pa increasing CO2 concentration scenario. By adjusting the effective climate sensitivity (equivalent to the equilibrium climate sensitivity for an energy balance model) of MIROC-lite, the transient warming of the LCM could be adjusted to closely follow the low sensitivity (with an equilibrium climate sensitivity of 4.0 K

Development of a system emulating the global carbon cycle in Earth system models

Directory of Open Access Journals (Sweden)

K. Tachiiri

2010-08-01

Full Text Available Recent studies have indicated that the uncertainty in the global carbon cycle may have a significant impact on the climate. Since state of the art models are too computationally expensive for it to be possible to explore their parametric uncertainty in anything approaching a comprehensive fashion, we have developed a simplified system for investigating this problem. By combining the strong points of general circulation models (GCMs, which contain detailed and complex processes, and Earth system models of intermediate complexity (EMICs, which are quick and capable of large ensembles, we have developed a loosely coupled model (LCM which can represent the outputs of a GCM-based Earth system model, using much smaller computational resources. We address the problem of relatively poor representation of precipitation within our EMIC, which prevents us from directly coupling it to a vegetation model, by coupling it to a precomputed transient simulation using a full GCM. The LCM consists of three components: an EMIC (MIROC-lite which consists of a 2-D energy balance atmosphere coupled to a low resolution 3-D GCM ocean (COCO including an ocean carbon cycle (an NPZD-type marine ecosystem model; a state of the art vegetation model (Sim-CYCLE; and a database of daily temperature, precipitation, and other necessary climatic fields to drive Sim-CYCLE from a precomputed transient simulation from a state of the art AOGCM. The transient warming of the climate system is calculated from MIROC-lite, with the global temperature anomaly used to select the most appropriate annual climatic field from the pre-computed AOGCM simulation which, in this case, is a 1% pa increasing CO₂ concentration scenario.

By adjusting the effective climate sensitivity (equivalent to the equilibrium climate sensitivity for an energy balance model of MIROC-lite, the transient warming of the LCM could be adjusted to closely follow the low sensitivity (with an equilibrium

New era of satellite chlorophyll fluorescence and soil moisture observations leads to advances in the predictive understanding of global terrestrial coupled carbon-water cycles

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Qiu, B.; Xue, Y.; Fisher, J.; Guo, W.

2017-12-01

The terrestrial carbon cycle and water cycle are coupled through a multitude of connected processes among soil, roots, leaves, and the atmosphere. The strength and sensitivity of these couplings are not yet well known at the global scale, which contributes to uncertainty in predicting the terrestrial water and carbon budgets. For the first time, we now have synchronous, high fidelity, global-scale satellite observations of critical terrestrial carbon and water cycle components: sun-induced chlorophyll fluorescence (SIF) and soil moisture. We used these observations within the framework of a well-established global terrestrial biosphere model (Simplified Simple Biosphere Model version 2.0, SSiB2) to investigate carbon-water coupling processes. We updated SSiB2 to include a mechanistic representation of SIF and tested the sensitivity of model parameters to improve the simulation of both SIF and soil moisture with the ultimate objective of improving the first-order terrestrial carbon component, gross primary production (GPP). Although several vegetation parameters, such as leaf area index (LAI) and green leaf fraction, improved the simulated SIF, and several soil parameters, such as hydraulic conductivity, improved simulated soil moisture, their effects were mainly limited to their respective cycles. One parameter emerged as the key coupler between the carbon and water cycles: the wilting point. Updates to the wilting point significantly improved the simulations for both soil moisture and SIF, as well as GPP. This study demonstrates the value of synchronous global measurements of the terrestrial carbon and water cycles in improving the understanding of coupled carbon-water cycles.

The contribution of weathering of the main Alpine rivers on the global carbon cycle

Science.gov (United States)

Donnini, Marco; Probst, Jean-Luc; Probst, Anne; Frondini, Francesco; Marchesini, Ivan; Guzzetti, Fausto

2013-04-01

classification of Meybeck (1986, 1987). Then for each basin we computed Rsil weighted average considering the surface and the mean precipitation for the surface area of each lithology. Lastly, we estimated the (Ca+Mg) originating from carbonate weathering as the remaining cations after silicate correction. Depending on time-scales of the phenomena (shorter than about 1 million year i.e., correlated to the short term carbon cycle, or longer than about 1 million years i.e., correlated to the long-term carbon cycle), we considered different equations for the quantification of the atmospheric CO2 consumed by weathering (Huh, 2010). The results show the net predominance of carbonate weathering on fixing atmospheric CO2 and that, considering the long-term carbon cycle, the amount of atmospheric CO2 uptake by weathering is about one order of magnitude lower than considering the short-term carbon cycle. Moreover, considering the short-term carbon cycle, the mean CO2 consumed by Alpine basins is of the same order of magnitude of the mean CO2 consumed by weathering by the 60 largest rivers of the world estimated by Gaillardet et al. (1999). References Amiotte-Suchet, P. "Cycle Du Carbone, Érosion Chimique Des Continents Et Transfert Vers Les Océans." Sci. Géol. Mém. Strasbourg 97 (1995): 156. Amiotte-Suchet, P., and J.-L. Probst. "Origins of dissolved inorganic carbon in the Garonne river waters: seasonal and interannual variations." Sci. Géologiques Bull. Strasbourg 49, no. 1-4 (1996): 101-126. Berner, E.K., and R.A. Berner. The Global Water Cycle. Geochemistry and Environment. Prentice Halle. Engelwood Cliffs, NJ, 1987. Drever, J.L. The Geochemistry of Natural Waters. Prentice Hall, 1982. Gaillardet, J., B. Dupré, P. Louvat, and C.J. Allègre. "Global Silicate Weathering and CO2 Consumption Rates Deduced from the Chemistry of Large Rivers." Chemical Geology 159 (1999): 3-30. Garrels, R.M., and F.T. Mackenzie. Evolution of Sedimentary Rocks. New York: W.W. Nortonand, 1971. Huh, Y

Partitioning the effects of Global Warming on the Hydrological Cycle with Stable Isotopes in Water Vapor

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Dee, S. G.; Russell, J. M.; Nusbaumer, J. M.; Konecky, B. L.; Buenning, N. H.; Lee, J. E.; Noone, D.

2016-12-01

General circulation models (GCMs) suggest that much of the global hydrological cycle's response to anthropogenic warming will be caused by increased lower-tropospheric water vapor concentrations and associated feedbacks. However, fingerprinting changes in the global hydrological cycle due to anthropogenic warming remains challenging. Held and Soden (2006) predicted that as lower-tropospheric water vapor increases, atmospheric circulation will weaken as climate warms to maintain the surface energy budget. Unfortunately, the strength of this feedback and the fallout for other branches of the hydrological cycle is difficult to constrain in situ or with GCMs alone. We demonstrate the utility of stable hydrogen isotope ratios in atmospheric water vapor to quantitatively trace changes in atmospheric circulation and convective mass flux in a warming world. We compare water isotope-enabled GCM experiments for control (present-day) CO2 vs. high CO2(2x, 4x) atmospheres in two GCMs, IsoGSM and iCAM5. We evaluate changes in the distribution of water vapor, vertical velocity (omega), and the stream function between these experiments in order to identify spatial patterns of circulation change over the tropical Pacific (where vertical motion is strong) and map the δD of water vapor associated with atmospheric warming. We also probe the simulations to isolate isotopic signatures associated with water vapor residence time, precipitation efficiency, divergence, and cloud physics. We show that there are robust mechanisms that moisten the troposphere and weaken convective mass flux, and that these mechanisms can be tracked using the δD of water vapor. Further, we find that these responses are most pronounced in the upper troposphere. These findings provide a framework to develop new metrics for the detection of global warming impacts to the hydrological cycle. Further, currently available satellite missions measure δD in the atmospheric boundary layer, the free atmosphere, or the

Contribution of fish to the marine inorganic carbon cycle.

Science.gov (United States)

Wilson, R W; Millero, F J; Taylor, J R; Walsh, P J; Christensen, V; Jennings, S; Grosell, M

2009-01-16

Oceanic production of calcium carbonate is conventionally attributed to marine plankton (coccolithophores and foraminifera). Here we report that marine fish produce precipitated carbonates within their intestines and excrete these at high rates. When combined with estimates of global fish biomass, this suggests that marine fish contribute 3 to 15% of total oceanic carbonate production. Fish carbonates have a higher magnesium content and solubility than traditional sources, yielding faster dissolution with depth. This may explain up to a quarter of the increase in titratable alkalinity within 1000 meters of the ocean surface, a controversial phenomenon that has puzzled oceanographers for decades. We also predict that fish carbonate production may rise in response to future environmental changes in carbon dioxide, and thus become an increasingly important component of the inorganic carbon cycle.

Mammary-Specific Ablation of the Calcium-Sensing Receptor During Lactation Alters Maternal Calcium Metabolism, Milk Calcium Transport, and Neonatal Calcium Accrual

Science.gov (United States)

Mamillapalli, Ramanaiah; VanHouten, Joshua; Dann, Pamela; Bikle, Daniel; Chang, Wenhan; Brown, Edward

2013-01-01

To meet the demands for milk calcium, the lactating mother adjusts systemic calcium and bone metabolism by increasing dietary calcium intake, increasing bone resorption, and reducing renal calcium excretion. As part of this adaptation, the lactating mammary gland secretes PTHrP into the maternal circulation to increase bone turnover and mobilize skeletal calcium stores. Previous data have suggested that, during lactation, the breast relies on the calcium-sensing receptor (CaSR) to coordinate PTHrP secretion and milk calcium transport with calcium availability. To test this idea genetically, we bred BLG-Cre mice with CaSR-floxed mice to ablate the CaSR specifically from mammary epithelial cells only at the onset of lactation (CaSR-cKO mice). Loss of the CaSR in the lactating mammary gland did not disrupt alveolar differentiation or milk production. However, it did increase the secretion of PTHrP into milk and decreased the transport of calcium from the circulation into milk. CaSR-cKO mice did not show accelerated bone resorption, but they did have a decrease in bone formation. Loss of the mammary gland CaSR resulted in hypercalcemia, decreased PTH secretion, and increased renal calcium excretion in lactating mothers. Finally, loss of the mammary gland CaSR resulted in decreased calcium accrual by suckling neonates, likely due to the combination of increased milk PTHrP and decreased milk calcium. These results demonstrate that the mammary gland CaSR coordinates maternal bone and calcium metabolism, calcium transport into milk, and neonatal calcium accrual during lactation. PMID:23782944

Discovery and Development of Calcium Channel Blockers

Directory of Open Access Journals (Sweden)

Théophile Godfraind

2017-05-01

Full Text Available In the mid 1960s, experimental work on molecules under screening as coronary dilators allowed the discovery of the mechanism of calcium entry blockade by drugs later named calcium channel blockers. This paper summarizes scientific research on these small molecules interacting directly with L-type voltage-operated calcium channels. It also reports on experimental approaches translated into understanding of their therapeutic actions. The importance of calcium in muscle contraction was discovered by Sidney Ringer who reported this fact in 1883. Interest in the intracellular role of calcium arose 60 years later out of Kamada (Japan and Heibrunn (USA experiments in the early 1940s. Studies on pharmacology of calcium function were initiated in the mid 1960s and their therapeutic applications globally occurred in the the 1980s. The first part of this report deals with basic pharmacology in the cardiovascular system particularly in isolated arteries. In the section entitled from calcium antagonists to calcium channel blockers, it is recalled that drugs of a series of diphenylpiperazines screened in vivo on coronary bed precontracted by angiotensin were initially named calcium antagonists on the basis of their effect in depolarized arteries contracted by calcium. Studies on arteries contracted by catecholamines showed that the vasorelaxation resulted from blockade of calcium entry. Radiochemical and electrophysiological studies performed with dihydropyridines allowed their cellular targets to be identified with L-type voltage-operated calcium channels. The modulated receptor theory helped the understanding of their variation in affinity dependent on arterial cell membrane potential and promoted the terminology calcium channel blocker (CCB of which the various chemical families are introduced in the paper. In the section entitled tissue selectivity of CCBs, it is shown that characteristics of the drug, properties of the tissue, and of the stimuli are

Seabird colonies as important global drivers in the nitrogen and phosphorus cycles.

Science.gov (United States)

Otero, Xosé Luis; De La Peña-Lastra, Saul; Pérez-Alberti, Augusto; Ferreira, Tiago Osorio; Huerta-Diaz, Miguel Angel

2018-01-23

Seabirds drastically transform the environmental conditions of the sites where they establish their breeding colonies via soil, sediment, and water eutrophication (hereafter termed ornitheutrophication). Here, we report worldwide amounts of total nitrogen (N) and total phosphorus (P) excreted by seabirds using an inventory of global seabird populations applied to a bioenergetics model. We estimate these fluxes to be 591 Gg N y -1 and 99 Gg P y -1 , respectively, with the Antarctic and Southern coasts receiving the highest N and P inputs. We show that these inputs are of similar magnitude to others considered in global N and P cycles, with concentrations per unit of surface area in seabird colonies among the highest measured on the Earth's surface. Finally, an important fraction of the total excreted N (72.5 Gg y -1 ) and P (21.8 Gg y -1 ) can be readily solubilized, increasing their short-term bioavailability in continental and coastal waters located near the seabird colonies.

The Global Nitrogen Cycle

Science.gov (United States)

Galloway, J. N.

2003-12-01

Once upon a time nitrogen did not exist. Today it does. In the intervening time the universe was formed, nitrogen was created, the Earth came into existence, and its atmosphere and oceans were formed! In this analysis of the Earth's nitrogen cycle, I start with an overview of these important events relative to nitrogen and then move on to the more traditional analysis of the nitrogen cycle itself and the role of humans in its alteration.The universe is ˜15 Gyr old. Even after its formation, there was still a period when nitrogen did not exist. It took ˜300 thousand years after the big bang for the Universe to cool enough to create atoms; hydrogen and helium formed first. Nitrogen was formed in the stars through the process of nucleosynthesis. When a star's helium mass becomes great enough to reach the necessary pressure and temperature, helium begins to fuse into still heavier elements, including nitrogen.Approximately 10 Gyr elapsed before Earth was formed (˜4.5 Ga (billion years ago)) by the accumulation of pre-assembled materials in a multistage process. Assuming that N2 was the predominate nitrogen species in these materials and given that the temperature of space is -270 °C, N2 was probably a solid when the Earth was formed since its boiling point (b.p.) and melting point (m.p.) are -196 °C and -210 °C, respectively. Towards the end of the accumulation period, temperatures were probably high enough for significant melting of some of the accumulated material. The volcanic gases emitted by the resulting volcanism strongly influenced the surface environment. Nitrogen was converted from a solid to a gas and emitted as N2. Carbon and sulfur were probably emitted as CO and H2S (Holland, 1984). N2 is still the most common nitrogen volcanic gas emitted today at a rate of ˜2 TgN yr-1 (Jaffee, 1992).Once emitted, the gases either remained in the atmosphere or were deposited to the Earth's surface, thus continuing the process of biogeochemical cycling. The rate of

A model of the solar cycle driven by the dynamo action of the global convection in the solar convection zone

International Nuclear Information System (INIS)

Yoshimura, H.

1976-01-01

Extensive numerical studies of the dynamo equations due to the global convection are presented to simulate the solar cycle and to open the way to study general stellar magnetic cycles. The dynamo equations which represent the longitudinally-averaged magnetohydrodynamical action (mean magnetohydrodynamics) of the global convection under the influence of the rotation in the solar convection zone are considered here as an initial boundary-value problem. The latitudinal and radial structure of the dynamo action consisting of a generation action due to the differential rotation and a regeneration action due to the global convection is parameterized in accordance with the structure of the rotation and of the global convection. This is done especially in such a way as to represent the presence of the two cells of the regeneration action in the radial direction in which the action has opposite signs, which is typical of the regeneration action of the global convection. The effects of the dynamics of the global convection (e.g., the effects of the stratification of the physical conditions in the solar convection zone) are presumed to be all included in those parameters used in the model and they are presumed not to alter the results drastically since these effects are only to change the structure of the regeneration action topologically. (Auth.)

Global warming potential of the sulfur-iodine process using life cycle assessment methodology

International Nuclear Information System (INIS)

Lattin, William C.; Utgikar, Vivek P.

2009-01-01

A life cycle assessment (LCA) of one proposed method of hydrogen production - thermochemical water-splitting using the sulfur-iodine cycle couple with a very high-temperature nuclear reactor - is presented in this paper. Thermochemical water-splitting theoretically offers a higher overall efficiency than high-temperature electrolysis of water because heat from the nuclear reactor is provided directly to the hydrogen generation process, instead of using the intermediate step of generating electricity. The primary heat source for the S-I cycle is an advanced nuclear reactor operating at temperatures corresponding to those required by the sulfur-iodine process. This LCA examines the environmental impact of the combined advanced nuclear and hydrogen generation plants and focuses on quantifying the emissions of carbon dioxide per kilogram of hydrogen produced. The results are presented in terms of global warming potential (GWP). The GWP of the system is 2500 g carbon dioxide-equivalent (CO 2 -eq) per kilogram of hydrogen produced. The GWP of this process is approximately one-sixth of that for hydrogen production by steam reforming of natural gas, and is comparable to producing hydrogen from wind- or hydro-electric conventional electrolysis. (author)

The Global Carbon Cycle: It's a Small World

Science.gov (United States)

Ineson, Philip; Milcu, Alexander; Subke, Jens-Arne; Wildman, Dennis; Anderson, Robert; Manning, Peter; Heinemeyer, Andreas

2010-05-01

Predicting future atmospheric concentrations of carbon dioxide (CO2), together with the impacts of these changes on global climate, are some of the most urgent and important challenges facing mankind. Modelling is the only way in which such predictions can be made, leading to the current generation of increasingly complex computer simulations, with associated concerns about embedded assumptions and conflicting model outputs. Alongside analysis of past climates, the GCMs currently represent our only hope of establishing the importance of potential runaway positive feedbacks linking climate change and atmospheric greenhouse gases yet the incorporation of necessary biospheric responses into GCMs markedly increases the uncertainty of predictions. Analysis of the importance of the major components of the global carbon (C) cycle reveals that an understanding of the conditions under which the terrestrial biosphere could switch from an overall carbon (C) sink to a source is critical to our ability to make future climate predictions. Here we present an alternative approach to assessing the short term biotic (plant and soil) sensitivities to elevated temperature and atmospheric CO2 through the use of a purely physical analogue. Centred on the concept of materially-closed systems containing scaled-down ratios of the global C stocks for the atmosphere, vegetation and soil we show that, in these model systems, the terrestrial biosphere is able to buffer a rise of 3oC even when coupled to very strong CO2-temperature positive feedbacks. The system respiratory response appears to be extremely well linked to temperature and is critical in deciding atmospheric concentrations of CO2. Simulated anthropogenic emissions of CO2 into the model systems showed an initial corresponding increase in atmospheric CO2 but, somewhat surprisingly, CO2 concentrations levelled off at ca. 480 p.p.m.v., despite continuing additions of CO2. Experiments were performed in which reversion of atmospheric

Simulations of the global carbon cycle and anthropogenic CO2 transient

International Nuclear Information System (INIS)

Sarmiento, J.L.

1994-01-01

This research focuses on improving the understanding of the anthropogenic carbon dioxide transient using observations and models of the past and present. In addition, an attempt is made to develop an ability to predict the future of the carbon cycle in response to continued anthropogenic perturbations and climate change. Three aspects of the anthropogenic carbon budget were investigated: (1) the globally integrated budget at the present time; (2) the time history of the carbon budget; and (3) the spatial distribution of carbon fluxes. One of the major activities of this study was the participation in the model comparison study of Enting, et al. [1994] carried out in preparation for the IPCC 1994 report

Global patterns of organic carbon export and sequestration in the ocean (Arne Richter Award for Outstanding Young Scientists)

Science.gov (United States)

Henson, S.; Sanders, R.; Madsen, E.; Le Moigne, F.; Quartly, G.

2012-04-01

A major term in the global carbon cycle is the ocean's biological carbon pump which is dominated by sinking of small organic particles from the surface ocean to its interior. Here we examine global patterns in particle export efficiency (PEeff), the proportion of primary production that is exported from the surface ocean, and transfer efficiency (Teff), the fraction of exported organic matter that reaches the deep ocean. This is achieved through extrapolating from in situ estimates of particulate organic carbon export to the global scale using satellite-derived data. Global scale estimates derived from satellite data show, in keeping with earlier studies, that PEeff is high at high latitudes and low at low latitudes, but that Teff is low at high latitudes and high at low latitudes. However, in contrast to the relationship observed for deep biomineral fluxes in previous studies, we find that Teff is strongly negatively correlated with opal export flux from the upper ocean, but uncorrelated with calcium carbonate export flux. We hypothesise that the underlying factor governing the spatial patterns observed in Teff is ecosystem function, specifically the degree of recycling occurring in the upper ocean, rather than the availability of calcium carbonate for ballasting. Finally, our estimate of global integrated carbon export is only 50% of previous estimates. The lack of consensus amongst different methodologies on the strength of the biological carbon pump emphasises that our knowledge of a major planetary carbon flux remains incomplete.

Calcium looping technology using improved stability nanostructured sorbent for cyclic CO{sub 2} capture

Energy Technology Data Exchange (ETDEWEB)

Luo, Cong; Zheng, Ying; Ding, Ning; Zheng, Chu-guang [Huazhong Univ. of Science and Technology, Wuhan (China). State Key Lab. of Coal Combustion

2013-07-01

One of the post-combustion CO{sub 2} capture technologies that have sufficiently been proved to be the best candidates for practical large scale post-combustion application is the calcium looping cycle. However, the CO{sub 2} capture capacity of a calcium-based sorbent derived from natural limestone decays through long-term cyclic utilization; thus, the development of novel sorbents to achieve a high CO{sub 2} capture capacity is an critical challenge for the calcium looping cycle technology. In this paper, we report the preparation and character of a new calcium-based sorbent produced via the combustion of a dry gel. The results show that the novel calcium-based sorbent has a much higher residual carbonation conversion as well as a better performance of anti-sintering when compared with the calcium-based sorbent derived from commercial micrometer grade CaCO{sub 3} and nanometer grade CaCO{sub 3}. It is reasonable to propose that the different final carbonation performances are induced by their different pore structures and BET surface areas rather than by different particle sizes. Compared with the commercial nano CaO, the morphology of the new sorbent shows a more rough porous appearance with hollow nanostructure. During carbonation, CO{sub 2} diffused more easily through the hollow structure than through a solid structure to reach the unreacted CaO. Besides, there is less chance for the hollow nanostructured particles to be merged together during the high temperature reactions.

Pulsed infrared radiation excites cultured neonatal spiral and vestibular ganglion neurons by modulating mitochondrial calcium cycling.

Science.gov (United States)

Lumbreras, Vicente; Bas, Esperanza; Gupta, Chhavi; Rajguru, Suhrud M

2014-09-15

Cochlear implants are currently the most effective solution for profound sensorineural hearing loss, and vestibular prostheses are under development to treat bilateral vestibulopathies. Electrical current spread in these neuroprostheses limits channel independence and, in some cases, may impair their performance. In comparison, optical stimuli that are spatially confined may result in a significant functional improvement. Pulsed infrared radiation (IR) has previously been shown to elicit responses in neurons. This study analyzes the response of neonatal rat spiral and vestibular ganglion neurons in vitro to IR (wavelength = 1,863 nm) using Ca(2+) imaging. Both types of neurons responded consistently with robust intracellular Ca(2+) ([Ca(2+)]i) transients that matched the low-frequency IR pulses applied (4 ms, 0.25-1 pps). Radiant exposures of ∼637 mJ/cm(2) resulted in continual neuronal activation. Temperature or [Ca(2+)] variations in the media did not alter the IR-evoked transients, ruling out extracellular Ca(2+) involvement or primary mediation by thermal effects on the plasma membrane. While blockage of Na(+), K(+), and Ca(2+) plasma membrane channels did not alter the IR-evoked response, blocking of mitochondrial Ca(2+) cycling with CGP-37157 or ruthenium red reversibly inhibited the IR-evoked [Ca(2+)]i transients. Additionally, the magnitude of the IR-evoked transients was dependent on ryanodine and cyclopiazonic acid-dependent Ca(2+) release. These results suggest that IR modulation of intracellular calcium cycling contributes to stimulation of spiral and vestibular ganglion neurons. As a whole, the results suggest selective excitation of neurons in the IR beam path and the potential of IR stimulation in future auditory and vestibular prostheses. Copyright © 2014 the American Physiological Society.

How does global biogeochemical cycle become complicated by terrestrial-aquatic interactions ?

Science.gov (United States)

Nakayama, Tadanobu; Maksyutov, Shamil

2015-04-01

Inland water such as river and lake are now known to be important and active components of global carbon cycle though its contribution has remained uncertain due to data scarcity (Battin et al., 2009; Aufdenkampe et al., 2011). The author has developed process-based National Integrated Catchment-based Eco-hydrology (NICE) model (Nakayama, 2008a-b, 2010, 2011a-b, 2012a-c, 2013; Nakayama and Fujita, 2010; Nakayama and Hashimoto, 2011; Nakayama and Shankman, 2013a-b; Nakayama and Watanabe, 2004, 2006, 2008a-b; Nakayama et al., 2006, 2007, 2010, 2012), which incorporates surface-groundwater interactions, includes up- and down-scaling processes between local-global scales, and can simulate iteratively nonlinear feedback between hydrologic, geomorphic, and ecological processes. In this study, NICE was coupled with various biogeochemical models to incorporate biogeochemical cycle including reaction between inorganic and organic carbons (DOC, POC, DIC, pCO2, etc.) in terrestrial and aquatic ecosystems including surface water and groundwater. The coupled model simulated CO2 evasion from inland water in global scale, was relatively in good agreement in that estimated by empirical regression model (Raymond et al., 2013). In particular, the simulated result implied importance of connectivity between terrestrial and aquatic ecosystems in addition to surface and groundwater, and hillslopes and stream channels, etc. The model further improved the accuracy of CH4 flux in wetland which is sensitive to fluctuations of shallow groundwater because the original NICE incorporates 3-D groundwater sub-model and simulates lateral subsurface flow more reasonably. This simulation system would play important role in integration of greenhouse gas budget of the biosphere, quantification of hot spots in boundless biogeochemical cycle, and bridging gap between top-down and bottom-up approaches (Cole et al., 2007; Frei et al., 2012; Kiel and Cardenas, 2014). References; Aufdenkampe, A.K., et al

SIGNIFICANCE OF THE CALCIUM DEFICIT IN PEDIATRICS AND WAYS TO CORRECT IT

Directory of Open Access Journals (Sweden)

O.A. Gromova

2007-01-01

Full Text Available Calcium takes an active part in provision and development of the motion function (tractions, transmission of the neural impulse, muscle reactions to the neural excitement, change of the hormone activity, realizing together with adenylate cyclase. But no less important is the calcium role in participation of the supporting tissue buildup, organization of the integral child's skeletal system, in which there is 99% of the body calcium. This is a sort of depot, in which the element is in the dynamic equilibrium with its level in blood. The skeletal system acts as a buffer to support the stable level of the calcium circulation in the course of the entire life cycle. The calcium deficit among children should fully be treated, frequently conducting therapy of the accompanied pathology of the gastrointestinal tract, liver and intestinal dysbiosis. We should exclude the hereditary pathology of the calcium exchange. For the usual growth of the human body and prevention of the senile osteoporosis, the necessary amount of calcium consumption should be provided from the very childhood of a person. For the prevention and treatment of the calcium deficit among children, we use specific calcium medications together with phosphorus, magnesium, microelements and vitamins tested in clinical practice and approved by the union of pediatricians of Russia.Key words: calcium, deficit of major mineral elements, treatment, prevention, children.

[Calcium suppletion for patients who use gastric acid inhibitors: calcium citrate or calcium carbonate?].

NARCIS (Netherlands)

Jonge, H.J. de; Gans, R.O.; Huls, G.A.

2012-01-01

Various calcium supplements are available for patients who have an indication for calcium suppletion. American guidelines and UpToDate recommend prescribing calcium citrate to patients who use antacids The rationale for this advice is that water-insoluble calcium carbonate needs acid for adequate

Functional, genetic and bioinformatic characterization of a calcium/calmodulin kinase gene in Sporothrix schenckii

Directory of Open Access Journals (Sweden)

Rodriguez-del Valle Nuri

2007-11-01

Full Text Available Abstract Background Sporothrix schenckii is a pathogenic, dimorphic fungus, the etiological agent of sporotrichosis, a subcutaneous lymphatic mycosis. Dimorphism in S. schenckii responds to second messengers such as cAMP and calcium, suggesting the possible involvement of a calcium/calmodulin kinase in its regulation. In this study we describe a novel calcium/calmodulin-dependent protein kinase gene in S. schenckii, sscmk1, and the effects of inhibitors of calmodulin and calcium/calmodulin kinases on the yeast to mycelium transition and the yeast cell cycle. Results Using the PCR homology approach a new member of the calcium/calmodulin kinase family, SSCMK1, was identified in this fungus. The cDNA sequence of sscmk1 revealed an open reading frame of 1,221 nucleotides encoding a 407 amino acid protein with a predicted molecular weight of 45.6 kDa. The genomic sequence of sscmk1 revealed the same ORF interrupted by five introns. Bioinformatic analyses of SSCMK1 showed that this protein had the distinctive features that characterize a calcium/calmodulin protein kinase: a serine/threonine protein kinase domain and a calmodulin-binding domain. When compared to homologues from seven species of filamentous fungi, SSCMK1 showed substantial similarities, except for a large and highly variable region that encompasses positions 330 – 380 of the multiple sequence alignment. Inhibition studies using calmodulin inhibitor W-7, and calcium/calmodulin kinase inhibitors, KN-62 and lavendustin C, were found to inhibit budding by cells induced to re-enter the yeast cell cycle and to favor the yeast to mycelium transition. Conclusion This study constitutes the first evidence of the presence of a calcium/calmodulin kinase-encoding gene in S. schenckii and its possible involvement as an effector of dimorphism in this fungus. These results suggest that a calcium/calmodulin dependent signaling pathway could be involved in the regulation of dimorphism in this fungus

Climate-induced interannual variability of marine primary and export production in three global coupled climate carbon cycle models

Directory of Open Access Journals (Sweden)

B. Schneider

2008-04-01

Full Text Available Fully coupled climate carbon cycle models are sophisticated tools that are used to predict future climate change and its impact on the land and ocean carbon cycles. These models should be able to adequately represent natural variability, requiring model validation by observations. The present study focuses on the ocean carbon cycle component, in particular the spatial and temporal variability in net primary productivity (PP and export production (EP of particulate organic carbon (POC. Results from three coupled climate carbon cycle models (IPSL, MPIM, NCAR are compared with observation-based estimates derived from satellite measurements of ocean colour and results from inverse modelling (data assimilation. Satellite observations of ocean colour have shown that temporal variability of PP on the global scale is largely dominated by the permanently stratified, low-latitude ocean (Behrenfeld et al., 2006 with stronger stratification (higher sea surface temperature; SST being associated with negative PP anomalies. Results from all three coupled models confirm the role of the low-latitude, permanently stratified ocean for anomalies in globally integrated PP, but only one model (IPSL also reproduces the inverse relationship between stratification (SST and PP. An adequate representation of iron and macronutrient co-limitation of phytoplankton growth in the tropical ocean has shown to be the crucial mechanism determining the capability of the models to reproduce observed interactions between climate and PP.

Comparing the Life Cycle Energy Consumption, Global Warming and Eutrophication Potentials of Several Water and Waste Service Options

Directory of Open Access Journals (Sweden)

Xiaobo Xue

2016-04-01

Full Text Available Managing the water-energy-nutrient nexus for the built environment requires, in part, a full system analysis of energy consumption, global warming and eutrophication potentials of municipal water services. As an example, we evaluated the life cycle energy use, greenhouse gas (GHG emissions and aqueous nutrient releases of the whole anthropogenic municipal water cycle starting from raw water extraction to wastewater treatment and reuse/discharge for five municipal water and wastewater systems. The assessed options included conventional centralized services and four alternative options following the principles of source-separation and water fit-for-purpose. The comparative life cycle assessment identified that centralized drinking water supply coupled with blackwater energy recovery and on-site greywater treatment and reuse was the most energy- and carbon-efficient water service system evaluated, while the conventional (drinking water and sewerage centralized system ranked as the most energy- and carbon-intensive system. The electricity generated from blackwater and food residuals co-digestion was estimated to offset at least 40% of life cycle energy consumption for water/waste services. The dry composting toilet option demonstrated the lowest life cycle eutrophication potential. The nutrients in wastewater effluent are the dominating contributors for the eutrophication potential for the assessed system configurations. Among the parameters for which variability and sensitivity were evaluated, the carbon intensity of the local electricity grid and the efficiency of electricity production by the co-digestion with the energy recovery process were the most important for determining the relative global warming potential results.

A road map for the realization of global-scale thorium breeding fuel cycle by single molten-fluoride flow

International Nuclear Information System (INIS)

Furukawa, K.; Arakawa, K.; Erbay, L. B.

2007-01-01

For global survival in this century, we urgently need to launch a completely new global nuclear fission industry. To get worldwide public acceptance of nuclear energy, improvements are essential not only on safety, radio-waste management and economy but also especially nuclear proliferation resistance and safeguards. However, such global fission industry cannot replace the present fossil fuel industry in the next 50 years, unless the doubling-time of nuclear energy is less than 10 years, preferably 5-7 years. Such a doubling-time cannot be established by any kind of classical 'Fission Breeding Power Station' concept. We need a symbiotic system which couples fission power reactors with a system which can convert fertile thorium to fissile U-233, such as a spallation or D/T fusion (if and when it becomes available). For such a purpose, THORIMS-NES [Thorium Molten-Salt Nuclear Energy Synergetic System] has been proposed, which is composed of simple thermal fission power stations (FUJI) and fissile producing Accelerator Molten-Salt Breeder (AMSB). Its system functions are very ambitious, delicate and complex, but can be realized in the form of simple hardware applying the multifunctional 'single-phase molten-fluoride' circulation system. This system has no difficulties relating with 'radiation-damage', 'heat-removal' and 'chemical processing' owing to the simple 'idealistic ionic liquid' character. FUJI is size-flexible (economical even in smaller sizes), fuel self-sustaining without any continuous chemical processing and without core-graphite replacement, and AMSB is based on a single-fluid molten-salt target/blanket concept, which solves most engineering difficulties such as radiation-damage, heat-removal etc., except high-current proton accelerator development. Several AMSBs are accommodated in the regional centers (several ten sites in the world) with batch chemical processing plants including radio-waste management. The integrated thorium breeding fuel cycle is

Proceedings of the GLOBAL 2009 congress - The Nuclear Fuel Cycle: Sustainable Options and Industrial Perspectives

International Nuclear Information System (INIS)

2009-06-01

GLOBAL 2009 is the ninth bi-annual scientific world meeting on the Nuclear Fuel Cycle (NFC) that started in 1993 in Seattle. This meeting has established itself as a dedicated international forum for experts, to provide an overall review of the status and new trends of research applications and policies related to the fuel cycle. The international nuclear community is actively developing advanced processes and innovative technologies that enhance economic competitiveness of nuclear energy and ensure its sustainability, through optimized utilization of natural resources, minimization of nuclear wastes, resistance to proliferation and compliance with safety requirements. In this context, and under the profound evolutions concerning energy supply, GLOBAL 2009 is a great opportunity for sharing ideas and visions on the NFC. Special emphasis are placed on the results of the international studies for developing next generation systems. GLOBAL 2009 highlights the technical challenges and successes involved in closing the NFC and recycling long lived nuclear waste. It is also an excellent occasion to review and discuss social and regulatory aspects as well as national plans and international policies and decision affecting the future of nuclear energy. This meeting provides a forum for the exchange of the newest ideas and developments related to the initiatives at of establishing an acceptable, reliable and universal international non proliferation regime. The congress, organized by the French Nuclear Energy Society (SFEN), under the aegis of the IAEA, NEA of the OECD and the UE Commission with the basic sponsorships of ANS, ENS and AESJ, combines plenary sessions, general panel sessions, parallel sessions and technical visits. The program has full length technical papers, which are peer reviewed and published in conference proceedings. A large industrial exhibition takes place to complement the congress. The GLOBAL 2009 congress is organized in coordination with the 2009

Proceedings of the GLOBAL 2009 congress - The Nuclear Fuel Cycle: Sustainable Options and Industrial Perspectives

Energy Technology Data Exchange (ETDEWEB)

NONE

2009-06-15

GLOBAL 2009 is the ninth bi-annual scientific world meeting on the Nuclear Fuel Cycle (NFC) that started in 1993 in Seattle. This meeting has established itself as a dedicated international forum for experts, to provide an overall review of the status and new trends of research applications and policies related to the fuel cycle. The international nuclear community is actively developing advanced processes and innovative technologies that enhance economic competitiveness of nuclear energy and ensure its sustainability, through optimized utilization of natural resources, minimization of nuclear wastes, resistance to proliferation and compliance with safety requirements. In this context, and under the profound evolutions concerning energy supply, GLOBAL 2009 is a great opportunity for sharing ideas and visions on the NFC. Special emphasis are placed on the results of the international studies for developing next generation systems. GLOBAL 2009 highlights the technical challenges and successes involved in closing the NFC and recycling long lived nuclear waste. It is also an excellent occasion to review and discuss social and regulatory aspects as well as national plans and international policies and decision affecting the future of nuclear energy. This meeting provides a forum for the exchange of the newest ideas and developments related to the initiatives at of establishing an acceptable, reliable and universal international non proliferation regime. The congress, organized by the French Nuclear Energy Society (SFEN), under the aegis of the IAEA, NEA of the OECD and the UE Commission with the basic sponsorships of ANS, ENS and AESJ, combines plenary sessions, general panel sessions, parallel sessions and technical visits. The program has full length technical papers, which are peer reviewed and published in conference proceedings. A large industrial exhibition takes place to complement the congress. The GLOBAL 2009 congress is organized in coordination with the 2009

Comparative transcriptome analysis reveals different molecular mechanisms of Bacillus coagulans 2-6 response to sodium lactate and calcium lactate during lactic acid production.

Directory of Open Access Journals (Sweden)

Jiayang Qin

Full Text Available Lactate production is enhanced by adding calcium carbonate or sodium hydroxide during fermentation. However, Bacillus coagulans 2-6 can produce more than 180 g/L L-lactic acid when calcium lactate is accumulated, but less than 120 g/L L-lactic acid when sodium lactate is formed. The molecular mechanisms by which B. coagulans responds to calcium lactate and sodium lactate remain unclear. In this study, comparative transcriptomic methods based on high-throughput RNA sequencing were applied to study gene expression changes in B. coagulans 2-6 cultured in non-stress, sodium lactate stress and calcium lactate stress conditions. Gene expression profiling identified 712 and 1213 significantly regulated genes in response to calcium lactate stress and sodium lactate stress, respectively. Gene ontology assignments of the differentially expressed genes were performed. KEGG pathway enrichment analysis revealed that 'ATP-binding cassette transporters' were significantly affected by calcium lactate stress, and 'amino sugar and nucleotide sugar metabolism' was significantly affected by sodium lactate stress. It was also found that lactate fermentation was less affected by calcium lactate stress than by sodium lactate stress. Sodium lactate stress had negative effect on the expression of 'glycolysis/gluconeogenesis' genes but positive effect on the expression of 'citrate cycle (TCA cycle' genes. However, calcium lactate stress had positive influence on the expression of 'glycolysis/gluconeogenesis' genes and had minor influence on 'citrate cycle (TCA cycle' genes. Thus, our findings offer new insights into the responses of B. coagulans to different lactate stresses. Notably, our RNA-seq dataset constitute a robust database for investigating the functions of genes induced by lactate stress in the future and identify potential targets for genetic engineering to further improve L-lactic acid production by B. coagulans.

Comparative transcriptome analysis reveals different molecular mechanisms of Bacillus coagulans 2-6 response to sodium lactate and calcium lactate during lactic acid production.

Science.gov (United States)

Qin, Jiayang; Wang, Xiuwen; Wang, Landong; Zhu, Beibei; Zhang, Xiaohua; Yao, Qingshou; Xu, Ping

2015-01-01

Lactate production is enhanced by adding calcium carbonate or sodium hydroxide during fermentation. However, Bacillus coagulans 2-6 can produce more than 180 g/L L-lactic acid when calcium lactate is accumulated, but less than 120 g/L L-lactic acid when sodium lactate is formed. The molecular mechanisms by which B. coagulans responds to calcium lactate and sodium lactate remain unclear. In this study, comparative transcriptomic methods based on high-throughput RNA sequencing were applied to study gene expression changes in B. coagulans 2-6 cultured in non-stress, sodium lactate stress and calcium lactate stress conditions. Gene expression profiling identified 712 and 1213 significantly regulated genes in response to calcium lactate stress and sodium lactate stress, respectively. Gene ontology assignments of the differentially expressed genes were performed. KEGG pathway enrichment analysis revealed that 'ATP-binding cassette transporters' were significantly affected by calcium lactate stress, and 'amino sugar and nucleotide sugar metabolism' was significantly affected by sodium lactate stress. It was also found that lactate fermentation was less affected by calcium lactate stress than by sodium lactate stress. Sodium lactate stress had negative effect on the expression of 'glycolysis/gluconeogenesis' genes but positive effect on the expression of 'citrate cycle (TCA cycle)' genes. However, calcium lactate stress had positive influence on the expression of 'glycolysis/gluconeogenesis' genes and had minor influence on 'citrate cycle (TCA cycle)' genes. Thus, our findings offer new insights into the responses of B. coagulans to different lactate stresses. Notably, our RNA-seq dataset constitute a robust database for investigating the functions of genes induced by lactate stress in the future and identify potential targets for genetic engineering to further improve L-lactic acid production by B. coagulans.

A global coal production forecast with multi-Hubbert cycle analysis

Energy Technology Data Exchange (ETDEWEB)

Patzek, Tadeusz W. [Department of Petroleum and Geosystems Engineering, The University of Texas, Austin, TX 78712 (United States); Croft, Gregory D. [Department of Civil and Environmental Engineering, The University of California, Berkeley, Davis Hall, CA 94720 (United States)

2010-08-15

Based on economic and policy considerations that appear to be unconstrained by geophysics, the Intergovernmental Panel on Climate Change (IPCC) generated forty carbon production and emissions scenarios. In this paper, we develop a base-case scenario for global coal production based on the physical multi-cycle Hubbert analysis of historical production data. Areas with large resources but little production history, such as Alaska and the Russian Far East, are treated as sensitivities on top of this base-case, producing an additional 125 Gt of coal. The value of this approach is that it provides a reality check on the magnitude of carbon emissions in a business-as-usual (BAU) scenario. The resulting base-case is significantly below 36 of the 40 carbon emission scenarios from the IPCC. The global peak of coal production from existing coalfields is predicted to occur close to the year 2011. The peak coal production rate is 160 EJ/y, and the peak carbon emissions from coal burning are 4.0 Gt C (15 Gt CO{sub 2}) per year. After 2011, the production rates of coal and CO{sub 2} decline, reaching 1990 levels by the year 2037, and reaching 50% of the peak value in the year 2047. It is unlikely that future mines will reverse the trend predicted in this BAU scenario. (author)

21 CFR 172.330 - Calcium pantothenate, calcium chloride double salt.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium pantothenate, calcium chloride double salt... FOOD FOR HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.330 Calcium pantothenate, calcium chloride double salt. The food additive calcium chloride double salt of calcium pantothenate may...

Evaluation and intercomparison of three-dimensional global marine carbon cycle models

Energy Technology Data Exchange (ETDEWEB)

Caldeira, K., LLNL

1998-07-01

-Reimer, 1990; Sarmiento et al., 1992, Najjar et al., 1992). These twin needs for the development of marine carbon cycle models are expressed in two of the main elements of JGOFS SMP: (1) extrapolation and prediction, and (2) global and regional balances of carbon and related biologically-active substances. We propose to address these program elements through a coordinated, multi-investigator project to evaluate and intercompare several 3-D global marine carbon cycle models.

Municipal solid waste conversion to transportation fuels: a life-cycle estimation of global warming potential and energy consumption

DEFF Research Database (Denmark)

Pressley, Phillip N.; Aziz, Tarek N.; DeCarolis, Joseph F.

2014-01-01

This paper utilizes life cycle assessment (LCA) methodology to evaluate the conversion of U.S. municipal solid waste (MSW) to liquid transportation fuels via gasification and Fischer-Tropsch (FT). The model estimates the cumulative energy demand and global warming potential (GWP) associated...

Comparing the Life Cycle Energy Consumption, Global Warming and Eutrophication Potentials of Several Water and Waste Service Options

Science.gov (United States)

Managing the water-energy-nutrient nexus for the built environment requires, in part, a full system analysis of energy consumption, global warming and eutrophication potentials of municipal water services. As an example, we evaluated the life cycle energy use, greenhouse gas (GHG...

The mechanical environment modulates intracellular calcium oscillation activities of myofibroblasts.

Directory of Open Access Journals (Sweden)

Charles Godbout

Full Text Available Myofibroblast contraction is fundamental in the excessive tissue remodeling that is characteristic of fibrotic tissue contractures. Tissue remodeling during development of fibrosis leads to gradually increasing stiffness of the extracellular matrix. We propose that this increased stiffness positively feeds back on the contractile activities of myofibroblasts. We have previously shown that cycles of contraction directly correlate with periodic intracellular calcium oscillations in cultured myofibroblasts. We analyze cytosolic calcium dynamics using fluorescent calcium indicators to evaluate the possible impact of mechanical stress on myofibroblast contractile activity. To modulate extracellular mechanics, we seeded primary rat subcutaneous myofibroblasts on silicone substrates and into collagen gels of different elastic modulus. We modulated cell stress by cell growth on differently adhesive culture substrates, by restricting cell spreading area on micro-printed adhesive islands, and depolymerizing actin with Cytochalasin D. In general, calcium oscillation frequencies in myofibroblasts increased with increasing mechanical challenge. These results provide new insight on how changing mechanical conditions for myofibroblasts are encoded in calcium oscillations and possibly explain how reparative cells adapt their contractile behavior to the stresses occurring in normal and pathological tissue repair.

Global ice volume variations through the last glacial cycle simulated by a 3-D ice-dynamical model

NARCIS (Netherlands)

Bintanja, R.; Wal, R.S.W. van de; Oerlemans, J.

2002-01-01

A coupled ice sheet—ice shelf—bedrock model was run at 20km resolution to simulate the evolution of global ice cover during the last glacial cycle. The mass balance model uses monthly mean temperature and precipitation as input and incorporates the albedo—mass balance feedback. The model is forced

Refined global methyl halide budgets with respect to rapeseed (Brassica napus) by life-cycle measurements

Science.gov (United States)

Jiao, Y.; Acdan, J.; Xu, R.; Deventer, M. J.; Rhew, R. C.

2017-12-01

A precise quantification of global methyl halide budgets is needed to evaluate the ozone depletion potential of these compounds and to predict future changes of stratospheric ozone. However, the global budgets of methyl halides are not balanced between currently identified and quantified sources and sinks. Our study re-evaluated the methyl bromide budget from global cultivated rapeseed (Brassica napus) through life-cycle flux measurements both in the greenhouse and in the field, yielding a methyl bromide emission rate that scales globally to 1.0 - 1.2 Gg yr-1. While this indicates a globally significant source, it is much smaller than the previously widely cited value of 5 - 6 Gg yr-1(Mead et al., 2008), even taking into account the near tripling of annual global yield of rapeseed since the previous evaluation was conducted. Our study also evaluated the methyl chloride and methyl iodide emission levels from rapeseed, yielding emission rates that scale to 5.4 Gg yr-1 for methyl chloride and 1.8 Gg yr-1 of methyl iodide. The concentrations of the methyl donor SAM (S-adenosyl methionine) and the resultant product SAH (S-Adenosyl-L-homocysteine) were also analyzed to explore their role in biogenic methyl halide formation. Halide gradient incubations showed that the magnitude of methyl halide emissions from rapeseed is highly correlated to soil halide levels, thus raising the concern that the heterogeneity of soil halide contents geographically should be considered when extrapolating to global budget.

Determination of percent calcium carbonate in calcium chromate

International Nuclear Information System (INIS)

Middleton, H.W.

1979-01-01

The precision, accuracy and reliability of the macro-combustion method is superior to the Knorr alkalimetric method, and it is faster. It also significantly reduces the calcium chromate waste accrual problem. The macro-combustion method has been adopted as the official method for determination of percent calcium carbonate in thermal battery grade anhydrous calcium chromate and percent calcium carbonate in quicklime used in the production of calcium chromate. The apparatus and procedure can be used to measure the percent carbonate in inorganic materials other than calcium chromate. With simple modifications in the basic apparatus and procedure, the percent carbon and hydrogen can be measured in many organic material, including polymers and polymeric formulations. 5 figures, 5 tables

Late calcium EDTA rescues hippocampal CA1 neurons from global ischemia-induced death.

Science.gov (United States)

Calderone, Agata; Jover, Teresa; Mashiko, Toshihiro; Noh, Kyung-min; Tanaka, Hidenobu; Bennett, Michael V L; Zukin, R Suzanne

2004-11-03

Transient global ischemia induces a delayed rise in intracellular Zn2+, which may be mediated via glutamate receptor 2 (GluR2)-lacking AMPA receptors (AMPARs), and selective, delayed death of hippocampal CA1 neurons. The molecular mechanisms underlying Zn2+ toxicity in vivo are not well delineated. Here we show the striking finding that intraventricular injection of the high-affinity Zn2+ chelator calcium EDTA (CaEDTA) at 30 min before ischemia (early CaEDTA) or at 48-60 hr (late CaEDTA), but not 3-6 hr, after ischemia, afforded robust protection of CA1 neurons in approximately 50% (late CaEDTA) to 75% (early CaEDTA) of animals. We also show that Zn2+ acts via temporally distinct mechanisms to promote neuronal death. Early CaEDTA attenuated ischemia-induced GluR2 mRNA and protein downregulation (and, by inference, formation of Zn2+-permeable AMPARs), the delayed rise in Zn2+, and neuronal death. These findings suggest that Zn2+ acts at step(s) upstream from GluR2 gene downregulation and implicate Zn2+ in transcriptional regulation and/or GluR2 mRNA stability. Early CaEDTA also blocked mitochondrial release of cytochrome c and Smac/DIABLO (second mitochondria-derived activator of caspases/direct inhibitor of apoptosis protein-binding protein with low pI), caspase-3 activity (but not procaspase-3 cleavage), p75NTR induction, and DNA fragmentation. These findings indicate that CaEDTA preserves the functional integrity of the mitochondrial outer membrane and arrests the caspase death cascade. Late injection of CaEDTA at a time when GluR2 is downregulated and caspase is activated inhibited the delayed rise in Zn2+, p75NTR induction, DNA fragmentation, and cell death. The finding of neuroprotection by late CaEDTA administration has striking implications for intervention in the delayed neuronal death associated with global ischemia.

Soil carbon model alternatives for ECHAM5/JSBACH climate model: Evaluation and impacts on global carbon cycle estimates

DEFF Research Database (Denmark)

Thum, T.; Raisanen, P.; Sevanto, S.

2011-01-01

The response of soil organic carbon to climate change might lead to significant feedbacks affecting global warming. This response can be studied by coupled climate-carbon cycle models but so far the description of soil organic carbon cycle in these models has been quite simple. In this work we used...... the coupled climate-carbon cycle model ECHAM5/JSBACH (European Center/Hamburg Model 5/Jena Scheme for Biosphere-Atmosphere Coupling in Hamburg) with two different soil carbon modules, namely (1) the original soil carbon model of JSBACH called CBALANCE and (2) a new soil carbon model Yasso07, to study...... the interaction between climate variability and soil organic carbon. Equivalent ECHAM5/JSBACH simulations were conducted using both soil carbon models, with freely varying atmospheric CO2 for the last 30 years (1977-2006). In this study, anthropogenic CO2 emissions and ocean carbon cycle were excluded. The new...

Calcium-responsive contractility during fertilization in sea urchin eggs.

Science.gov (United States)

Stack, Christianna; Lucero, Amy J; Shuster, Charles B

2006-04-01

Fertilization triggers a reorganization of oocyte cytoskeleton, and in sea urchins, there is a dramatic increase in cortical F-actin. However, the role that myosin II plays during fertilization remains largely unexplored. Myosin II is localized to the cortical cytoskeleton both before and after fertilization and to examine myosin II contractility in living cells, Lytechinus pictus eggs were observed by time-lapse microscopy. Upon sperm binding, a cell surface deflection traversed the egg that was followed by and dependent on the calcium wave. The calcium-dependence of surface contractility could be reproduced in unfertilized eggs, where mobilization of intracellular calcium in unfertilized eggs under compression resulted in a marked contractile response. Lastly, inhibition of myosin II delayed absorption of the fertilization cone, suggesting that myosin II not only responds to the same signals that activate eggs but also participates in the remodeling of the cortical actomyosin cytoskeleton during the first zygotic cell cycle. (c) 2006 Wiley-Liss, Inc.

The Policy Cycle and Vernacular Globalization: A Case Study of the Creation of Vietnam National University--Hochiminh City

Science.gov (United States)

Minh Ngo, Thanh; Lingard, Bob; Mitchell, Jane

2006-01-01

This article examines the policy cycle and vernacular globalization in the context of higher education reform in Vietnam. Through an analysis of the development of the Vietnam National University--Hochiminh City as part of the post-1986 reconstruction of Vietnamese higher education, the article considers the complex interrelationship between…

Finnish and Swedish business cycles in a global context

DEFF Research Database (Denmark)

Bergman, Ulf Michael

2008-01-01

This paper evaluates the decisions made by the Finnish government to join EMU and the Swedish government not to join EMU in the early 1990s. Focusing on the characteristics of business cycles during the postwar period, we find that output fluctuations in Sweden and Finland are correlated to two...... measures of the international business cycle, a European and a non-European cycle. The Finnish cycle has become more synchronized to the European cycle but less synchronized to the non-EU cycle after 1999. For Sweden we find the opposite result. The decision by the Finnish government to join EMU...

The Circadian Clock Modulates Global Daily Cycles of mRNA Ribosome Loading[OPEN

Science.gov (United States)

Missra, Anamika; Ernest, Ben; Jia, Qidong; Ke, Kenneth

2015-01-01

Circadian control of gene expression is well characterized at the transcriptional level, but little is known about diel or circadian control of translation. Genome-wide translation state profiling of mRNAs in Arabidopsis thaliana seedlings grown in long day was performed to estimate ribosome loading per mRNA. The experiments revealed extensive translational regulation of key biological processes. Notably, translation of mRNAs for ribosomal proteins and mitochondrial respiration peaked at night. Central clock mRNAs are among those subject to fluctuations in ribosome loading. There was no consistent phase relationship between peak translation states and peak transcript levels. The overlay of distinct transcriptional and translational cycles can be expected to alter the waveform of the protein synthesis rate. Plants that constitutively overexpress the clock gene CCA1 showed phase shifts in peak translation, with a 6-h delay from midnight to dawn or from noon to evening being particularly common. Moreover, cycles of ribosome loading that were detected under continuous light in the wild type collapsed in the CCA1 overexpressor. Finally, at the transcript level, the CCA1-ox strain adopted a global pattern of transcript abundance that was broadly correlated with the light-dark environment. Altogether, these data demonstrate that gene-specific diel cycles of ribosome loading are controlled in part by the circadian clock. PMID:26392078

Evolution of the Calcium Paradigm: The Relation between Vitamin D, Serum Calcium and Calcium Absorption

Directory of Open Access Journals (Sweden)

Borje E. Christopher Nordin

2010-09-01

Full Text Available Osteoporosis is the index disease for calcium deficiency, just as rickets/osteomalacia is the index disease for vitamin D deficiency, but there is considerable overlap between them. The common explanation for this overlap is that hypovitaminosis D causes malabsorption of calcium which then causes secondary hyperparathyroidism and is effectively the same thing as calcium deficiency. This paradigm is incorrect. Hypovitaminosis D causes secondary hyperparathyroidism at serum calcidiol levels lower than 60 nmol/L long before it causes malabsorption of calcium because serum calcitriol (which controls calcium absorption is maintained until serum calcidiol falls below 20 nmol/L. This secondary hyperparathyroidism, probably due to loss of a “calcaemic” action of vitamin D on bone first described in 1957, destroys bone and explains why vitamin D insufficiency is a risk factor for osteoporosis. Vitamin D thus plays a central role in the maintenance of the serum (ionised calcium, which is more important to the organism than the preservation of the skeleton. Bone is sacrificed when absorbed dietary calcium does not match excretion through the skin, kidneys and bowel which is why calcium deficiency causes osteoporosis in experimental animals and, by implication, in humans.

Calcium absorption

International Nuclear Information System (INIS)

Carlmark, B.; Reizenstein, P.; Dudley, R.A.

1976-01-01

The methods most commonly used to measure the absorption and retention of orally administered calcium are reviewed. Nearly all make use of calcium radioisotopes. The magnitude of calcium absorption and retention depends upon the chemical form and amount of calcium administered, and the clinical and nutritional status of the subject; these influences are briefly surveyed. (author)

Exploring diurnal and seasonal characteristics of global carbon cycle with GISS Model E2 GCM

Science.gov (United States)

Aleinov, I. D.; Kiang, N. Y.; Romanou, A.

2017-12-01

The ability to properly model surface carbon fluxes on the diurnal and seasonal time scale is a necessary requirement for understanding of the global carbon cycle. It is also one of the most challenging tasks faced by modern General Circulation Models (GCMs) due to complexity of the algorithms and variety of relevant spatial and temporal scales. The observational data, though abundant, is difficult to interpret at the global scale, because flux tower observations are very sparse for large impact areas (such as Amazon and African rainforest and most of Siberia) and satellite missions often struggle to produce sufficiently high confidence data over the land and may be missing CO2 amounts near the surface due to the nature of the method. In this work we use the GISS Model E2 GCM to perform a subset of experiments proposed by the Coupled Climate-Carbon Cycle Model Intercomparison Project (C4MIP) and relate the results to available observations.The GISS Model E2 GCM is currently equipped with a complete global carbon cycle algorithm. Its surface carbon fluxes are computed by the Ent Terrestrial Biosphere Model (Ent TBM) over the land with observed leaf area index of the Moderate Resolution Imaging Spectrometer (MODIS) and by the NASA Ocean Biogeochemistry Model (NOBM) over the ocean. The propagation of atmospheric CO2 is performed by a generic Model E2 tracer algorithm, which is based on a quadratic upstream method (Prather 1986). We perform a series spin-up experiments for preindustrial climate conditions and fixed preindustrial atmospheric CO2 concentration. First, we perform separate spin-up simulations each for terrestrial and ocean carbon. We then combine the spun-up states and perform a coupled spin-up simulation until the model reaches a sufficient equilibrium. We then release restrictions on CO2 concentration and allow it evolve freely, driven only by simulated surface fluxes. We then study the results of the unforced run, comparing the amplitude and the phase

Dynamic model of the global iodine cycle for the estimation of dose to the world population from releases of iodine-129 to the environment

International Nuclear Information System (INIS)

Kocher, D.C.

1979-11-01

A dynamic linear compartment model of the global iodine cycle has been developed for the purpose of estimating long-term doses and dose commitments to the world population from releases of 129 I to the environment. The environmental compartments assumed in the model comprise the atmosphere, hydrosphere, lithosphere, and terrestrial biosphere. The global transport of iodine is described by means of time-invariant fractional transfer rates between the environmental compartments. The fractional transfer rates for 129 I are determined primarily from available data on compartment inventories and fluxes for naturally occurring stable iodine and from data on the global hydrologic cycle. The dose to the world population is estimated from the calculated compartment inventories of 129 I, the known compartment inventories of stable iodine, a pathway analysis of the intake of iodine by a reference individual, dose conversion factors for inhalation and ingestion, and an estimate of the world population. For an assumed constant population of 12.21 billion beyond the year 2075, the estimated population dose commitment is 2 x 10 5 man-rem/Ci. The sensitivity of the calculated doses to variations in some of the parameters in the model for the global iodine cycle is investigated. A computer code written to calculate global compartment inventories and dose rates and population doses is described and documented

The advanced fuel cycle facility (AFCF) role in the global nuclear energy partnership

International Nuclear Information System (INIS)

Griffith, Andrew

2007-01-01

The Global Nuclear Energy Partnership (GNEP), launched in February, 2006, proposes to introduce used nuclear fuel recycling in the United States with improved proliferation-resistance and a more effective waste management approach. This program is evaluating ways to close the fuel cycle in a manner that builds on recent laboratory breakthroughs in U.S. national laboratories and draws on international and industry partnerships. Central to moving this advanced fuel recycling technology from the laboratory to commercial implementation is a flexible research, development and demonstration facility, called the Advanced Fuel Cycle Facility (AFCF). The AFCF was introduced as one of three projects under GNEP and will provide the U.S. with the capabilities to evaluate technologies that separate used fuel into reusable material and waste in a proliferation-resistant manner. The separations technology demonstration capability is coupled with a remote transmutation fuel fabrication demonstration capability in an integrated manner that demonstrates advanced safeguard technologies. This paper will discuss the key features of AFCF and its support of the GNEP objectives. (author)

Increase of carbon cycle feedback with climate sensitivity: results from a coupled climate and carbon cycle model

International Nuclear Information System (INIS)

Govindasamy, B.; Thompson, S.; Mirin, A.; Wickett, M.; Caldeira, K.; Delire, C.

2005-01-01

Coupled climate and carbon cycle modelling studies have shown that the feedback between global warming and the carbon cycle, in particular the terrestrial carbon cycle, could accelerate climate change and result in greater warming. In this paper we investigate the sensitivity of this feedback for year 2100 global warming in the range of 0 to 8 K. Differing climate sensitivities to increased CO 2 content are imposed on the carbon cycle models for the same emissions. Emissions from the SRES A2 scenario are used. We use a fully coupled climate and carbon cycle model, the INtegrated Climate and CArbon model (INCCA), the NCAR/DOE Parallel Climate Model coupled to the IBIS terrestrial biosphere model and a modified OCMIP ocean biogeochemistry model. In our integrated model, for scenarios with year 2100 global warming increasing from 0 to 8 K, land uptake decreases from 47% to 29% of total CO 2 emissions. Due to competing effects, ocean uptake (16%) shows almost no change at all. Atmospheric CO 2 concentration increases are 48% higher in the run with 8 K global climate warming than in the case with no warming. Our results indicate that carbon cycle amplification of climate warming will be greater if there is higher climate sensitivity to increased atmospheric CO 2 content; the carbon cycle feedback factor increases from 1.13 to 1.48 when global warming increases from 3.2 to 8 K

Radioisotope 45Ca labeling four calcium chemical compounds and tracing calcium bioavailability

International Nuclear Information System (INIS)

Zheng Hui; Zhen Rong; Niu Huisheng; Li Huaifen

2004-01-01

Objective: To build up a new method of the radioisotope 45 Ca labeling four calcium chemical compounds, observe and tracing bioavailability change of calcium labeled with radioisotope 45 Ca. Methods: The calcium gluconate (Ca-Glu), calcium citrate (Ca-Cit), calcium carbonate (Ca-Car) and calcium L-threonate (Ca-Thr)were labeled by radioisotope 45 Ca. Four calcium chemical compounds of 45 Ca labeling were used of calcium content 200 mg/kg in the rats and measure the absorption content and bioavailability of calcium in tissue of heart, lever spleen, stomach, kidney, brain, intestine, whole blood, urine, faeces. Results: 1) Radioisotope 45 Ca labeling calcium chemical compound has high radio intensity, more steady standard curve and recover rate. 2) The absorption of organic calcium chemical compounds is higher than the inorganic calcium chemical compound in the study of calcium bioavailability. Conclusion: The method of tracing with radioisotope 45 Ca labeling calcium chemical compounds has the characteristic of the sensitive, objective, accurate and steady in the study of calcium bioavailability

The impact of calcium assay change on a local adjusted calcium equation.

Science.gov (United States)

Davies, Sarah L; Hill, Charlotte; Bailey, Lisa M; Davison, Andrew S; Milan, Anna M

2016-03-01

Deriving and validating local adjusted calcium equations is important for ensuring appropriate calcium status classification. We investigated the impact on our local adjusted calcium equation of a change in calcium method by the manufacturer from cresolphthalein complexone to NM-BAPTA. Calcium and albumin results from general practice requests were extracted from the Laboratory Information Management system for a three-month period. Results for which there was evidence of disturbance in calcium homeostasis were excluded leaving 13,482 sets of results for analysis. The adjusted calcium equation was derived following least squares regression analysis of total calcium on albumin and normalized to the mean calcium concentration of the data-set. The revised equation (NM-BAPTA calcium method) was compared with the previous equation (cresolphthalein complexone calcium method). The switch in calcium assay resulted in a small change in the adjusted calcium equation but was not considered to be clinically significant. The calcium reference interval differed from that proposed by Pathology Harmony in the UK. Local adjusted calcium equations should be re-assessed following changes in the calcium method. A locally derived reference interval may differ from the consensus harmonized reference interval. © The Author(s) 2015.

Simulating the Current Water Cycle with the NASA Ames Mars Global Climate Model

Science.gov (United States)

Kahre, M. A.; Haberle, R. M.; Hollingsworth, J. L.; Brecht, A. S.; Urata, R. A.; Montmessin, F.

2017-12-01

The water cycle is a critical component of the current Mars climate system, and it is now widely recognized that water ice clouds significantly affect the nature of the simulated water cycle. Two processes are key to implementing clouds in a Mars global climate model (GCM): the microphysical processes of formation and dissipation, and their radiative effects on atmospheric heating/cooling rates. Together, these processes alter the thermal structure, change the atmospheric dynamics, and regulate inter-hemispheric transport. We have made considerable progress using the NASA Ames Mars GCM to simulate the current-day water cycle with radiatively active clouds. Cloud fields from our baseline simulation are in generally good agreement with observations. The predicted seasonal extent and peak IR optical depths are consistent MGS/TES observations. Additionally, the thermal response to the clouds in the aphelion cloud belt (ACB) is generally consistent with observations and other climate model predictions. Notably, there is a distinct gap in the predicted clouds over the North Residual Cap (NRC) during local summer, but the clouds reappear in this simulation over the NRC earlier than the observations indicate. Polar clouds are predicted near the seasonal CO2 ice caps, but the column thicknesses of these clouds are generally too thick compared to observations. Our baseline simulation is dry compared to MGS/TES-observed water vapor abundances, particularly in the tropics and subtropics. These areas of disagreement appear to be a consistent with other current water cycle GCMs. Future avenues of investigation will target improving our understanding of what controls the vertical extent of clouds and the apparent seasonal evolution of cloud particle sizes within the ACB.

The global pyrogenic carbon cycle and its impact on the level of atmospheric CO2 over past and future centuries.

Science.gov (United States)

Landry, Jean-Sébastien; Matthews, H Damon

2017-08-01

The incomplete combustion of vegetation and dead organic matter by landscape fires creates recalcitrant pyrogenic carbon (PyC), which could be consequential for the global carbon budget if changes in fire regime, climate, and atmospheric CO 2 were to substantially affect gains and losses of PyC on land and in oceans. Here, we included global PyC cycling in a coupled climate-carbon model to assess the role of PyC in historical and future simulations, accounting for uncertainties through five sets of parameter estimates. We obtained year-2000 global stocks of (Central estimate, likely uncertainty range in parentheses) 86 (11-154), 47 (2-64), and 1129 (90-5892) Pg C for terrestrial residual PyC (RPyC), marine dissolved PyC, and marine particulate PyC, respectively. PyC cycling decreased atmospheric CO 2 only slightly between 1751 and 2000 (by 0.8 Pg C for the Central estimate) as PyC-related fluxes changed little over the period. For 2000 to 2300, we combined Representative Concentration Pathways (RCPs) 4.5 and 8.5 with stable or continuously increasing future fire frequencies. For the increasing future fire regime, the production of new RPyC generally outpaced the warming-induced accelerated loss of existing RPyC, so that PyC cycling decreased atmospheric CO 2 between 2000 and 2300 for most estimates (by 4-8 Pg C for Central). For the stable fire regime, however, PyC cycling usually increased atmospheric CO 2 (by 1-9 Pg C for Central), and only the most extreme choice of parameters maximizing PyC production and minimizing PyC decomposition led to atmospheric CO 2 decreases under RCPs 4.5 and 8.5 (by 5-8 Pg C). Our results suggest that PyC cycling will likely reduce the future increase in atmospheric CO 2 if landscape fires become much more frequent; however, in the absence of a substantial increase in fire frequency, PyC cycling might contribute to, rather than mitigate, the future increase in atmospheric CO 2 . © 2016 John Wiley & Sons Ltd.

Delayed recovery of non-marine tetrapods after the end-Permian mass extinction tracks global carbon cycle

OpenAIRE

Irmis, Randall B.; Whiteside, Jessica H.

2011-01-01

During the end-Permian mass extinction, marine ecosystems suffered a major drop in diversity, which was maintained throughout the Early Triassic until delayed recovery during the Middle Triassic. This depressed diversity in the Early Triassic correlates with multiple major perturbations to the global carbon cycle, interpreted as either intrinsic ecosystem or external palaeoenvironmental effects. In contrast, the terrestrial record of extinction and recovery is less clear; the effects and magn...

Dissolved strontium and calcium levels in the tropical Indian Ocean

Science.gov (United States)

Steiner, Zvi; Sarkar, Amit; Turchyn, Alexandra

2017-04-01

Measurements of seawater alkalinity and dissolved calcium concentrations along oceanic transects are often used to calculate calcium carbonate precipitation and dissolution rates. Given that the distribution coefficient of strontium in CaCO3 varies greatly between different groups of organisms, adding precise measurements of dissolved strontium concentrations provides opportunities to also track relative contributions of these different groups to the regional CaCO3 cycle. However, there are several obstacles to this approach. These obstacles include unresolved systematic discrepancies between seawater calcium and alkalinity data, very large analytical noise around the calcium concentration measurements and the unconstrained role of acantharia (radiolarian precipitating SrSO4 skeletons) in the marine strontium cycle. During the first cruise of the second International Indian Ocean Expedition (IIOE-2) water samples were collected along 67°E from 9°N to 5°S to explore the dissolution rate of calcium carbonate in the water. The dissolution rate can be calculated by combining measurements of water column potential alkalinity with calcium and strontium concentrations measured by ICP-OES and calcium concentration measurements using isotope dilution thermal ionization mass spectrometry (ID-TIMS). CaCO3 mineral saturation state calculated using pH and total alkalinity suggests that along 67°E, the aragonite saturation horizon lays at depth of 500 m on both sides of the equator. Across the cruise transect, dissolved strontium concentrations increase by 2-3% along the thermocline suggesting rapid recycling of strontium rich phases. This is particularly evident just below the thermocline at 8-9°N and below 1000 m water depth, south of the equator. The deep, southern enrichment in strontium does not involve a change in the Sr/Ca ratio, suggesting that this strontium enrichment is related to CaCO3 dissolution. In contrast, in the intermediate waters of the northern part of

Bcl-2 overexpression: effects on transmembrane calcium movement

International Nuclear Information System (INIS)

Rangaswami, Arun A.; Premack, Brett; Walleczek, Jan; Killoran, Pamela; Gardner, Phyllis; Knox, Susan J.

1996-01-01

Purpose/Objective: High levels of expression of the proto-oncogene bcl-2 and its 26 kD protein product Bcl-2 have been correlated with the inhibition of apoptosis and the increased resistance of tumor cells to cytotoxic drugs and ionizing radiation. Unfortunately, the specific mechanism of action of Bcl-2 remains poorly understood. In the studies described here, the role of intracellular calcium fluxes and plasma membrane calcium cycling in the induction of apoptosis, and the effect of Bcl-2 expression on the modulation of transmembrane calcium fluxes following treatment of cells with cytotoxic agents were studied. The relationship between intracellular calcium release, capacitive calcium entry, and the plasma membrane potential were also investigated. Materials and Methods: Human B-cell lymphoma (PW) and human promyelocytic leukemia (HL60) cell lines were transfected with Bcl-2 and a control vector. The Bcl-2 transfectants over expressed the Bcl-2 onco-protein and were more resistant to irradiation than the control cells. Cells were loaded with fluorescent indicators indo-1 and fura-2 AM to quantify the cytosolic calcium concentration and subsequent calcium responses to a variety of cytotoxic stimuli, including the microsomal ATPase inhibitor, thapsigargin, using fluorometric measurements. Comparisons of resting and stimulated cytosolic calcium concentrations were made between the parental, neomycin control, and bcl-2 transfected cells. In order to determine the actual calcium influx rate, cells were loaded with either indo-1 or fura-2 and then exposed to 0.1 mM extracellular manganese, which enters the cells through calcium influx channels and quenches the fluorescent signal in proportion to the calcium influx rate. In order to determine the role of the membrane potential in driving calcium influx, cells were treated with either 0.1 μM Valinomycin or isotonic potassium chloride to either hyper polarize or depolarize the resting membrane potential, and the

Calcium supplements

Science.gov (United States)

... this page: //medlineplus.gov/ency/article/007477.htm Calcium supplements To use the sharing features on this page, please enable JavaScript. WHO SHOULD TAKE CALCIUM SUPPLEMENTS? Calcium is an important mineral for the ...

Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model

International Nuclear Information System (INIS)

Cox, P.M.; Betts, R.A.; Jones, C.D.; Spall, S.A.; Totterdell, I.J.

2000-01-01

The continued increase in the atmospheric concentration of carbon dioxide due to anthropogenic emissions is predicted to lead to significant changes in climate. About half of the current emissions are being absorbed by the ocean and by land ecosystems, but this absorption is sensitive to climate as well as to atmospheric carbon dioxide concentrations, creating a feedback loop. General circulation models have generally excluded the feedback between climate and the biosphere, using static vegetation distributions and CO 2 concentrations from simple carbon-cycle models that do not include climate change. Here we present results from a fully coupled, three-dimensional carbon-climate model, indicating that carbon-cycle feedbacks could significantly accelerate climate change over the twenty-first century. We find that under a 'business as usual' scenario, the terrestrial biosphere acts as an overall carbon sink until about 2050, but turns into a source thereafter. By 2100, the ocean uptake rate of 5 Gt C yr -1 is balanced by the terrestrial carbon source, and atmospheric CO 2 concentrations are 250 p.p.m.v. higher in our fully coupled simulation than in uncoupled carbon models, resulting in a global-mean warming of 5.5 K, as compared to 4 K without the carbon-cycle feedback. (author)

Kajian Dampak Lingkungan Global dari Kegiatan Keramba Jaring Apung melalui Life Cycle Assessment (LCA

Directory of Open Access Journals (Sweden)

Tri Heru Prihadi

2016-11-01

Full Text Available Perubahan iklim global yang berlangsung saat ini memberikan pengaruh pada berbagai bidang, termasuk perikanan yang menyebabkan terjadinya degradasi lingkungan perairan. Hal ini berdampak pada muncul dan menyebarnya berbagai penyakit ikan, menurunnya laju pertumbuhan organisme perairan, bahkan hingga menimbulkan kematian massal ikan. Namun hal ini belum sepenuhnya dapat diatasi oleh para ilmuwan tanah air, bahkan bisa dikatakan baru sebagian kecil saja. Penerapan Best Management Practice (BMP dengan aplikasi Life Cycle Assessment (LCA akan sangat berarti dalam upaya penerapan perikanan budidaya berkelanjutan, dengan model pengelolaan kuantitatif. Dalam hal ini metode LCA secara kuantitatif merupakan pertama kalinya dilakukan di Indonesia. Penelitian ini bertujuan untuk mengetahui dan mengevaluasi kuantitas dan kategori dampak lingkungan akibat kegiatan budidaya keramba jaring apung (KJA melalui LCA. Hasil penelitian menunjukkan bahwa kegiatan budidaya di KJA menimbulkan dampak yang signifikan terhadap lingkungan perairan. Dari berbagai faktor yang berperan dalam kegiatan budidaya KJA, pakan ikan merupakan faktor yang paling dominan dalam menghasilkan dampak lingkungan global (di atas 70%, berupa pemanasan global, penurunan jumlah sumberdaya abiotik, eutrofikasi, penipisan lapisan ozon, toksisitas pada manusia, dan penurunan jumlah keanekaragaman hayati. Dari faktor pakan tersebut, unsur yang paling berpengaruh dalam menghasilkan dampak lingkungan adalah soybean Brazil dan winter wheat, sehingga perlu dicari alternatif bahan untuk mensubstitusi kedua unsur tersebut. Demikian juga faktor-faktor lainnya (seperti: polystyrene foams, drum plastik, bambu, jaring, besi, skala budidaya, dan lain-lain mempunyai peranan terhadap dampak yang ditimbulkan terhadap lingkungan perairan. Global climate change has been affecting many sectors, including fisheries causing aquatic environment degradation such as fish disease outbreaks, decreasing growth rate of fish

Recent Trends of the Tropical Hydrological Cycle Inferred from Global Precipitation Climatology Project and International Satellite Cloud Climatology Project data

Science.gov (United States)

Zhou, Y. P.; Xu, Kuan-Man; Sud, Y. C.; Betts, A. K.

2011-01-01

Scores of modeling studies have shown that increasing greenhouse gases in the atmosphere impact the global hydrologic cycle; however, disagreements on regional scales are large, and thus the simulated trends of such impacts, even for regions as large as the tropics, remain uncertain. The present investigation attempts to examine such trends in the observations using satellite data products comprising Global Precipitation Climatology Project precipitation and International Satellite Cloud Climatology Project cloud and radiation. Specifically, evolving trends of the tropical hydrological cycle over the last 20-30 years were identified and analyzed. The results show (1) intensification of tropical precipitation in the rising regions of the Walker and Hadley circulations and weakening over the sinking regions of the associated overturning circulation; (2) poleward shift of the subtropical dry zones (up to 2deg/decade in June-July-August (JJA) in the Northern Hemisphere and 0.3-0.7deg/decade in June-July-August and September-October-November in the Southern Hemisphere) consistent with an overall broadening of the Hadley circulation; and (3) significant poleward migration (0.9-1.7deg/decade) of cloud boundaries of Hadley cell and plausible narrowing of the high cloudiness in the Intertropical Convergence Zone region in some seasons. These results support findings of some of the previous studies that showed strengthening of the tropical hydrological cycle and expansion of the Hadley cell that are potentially related to the recent global warming trends.

The impact of the Cretaceous-Paleogene (K-Pg) mass extinction event on the global sulfur cycle: Evidence from Seymour Island, Antarctica

Science.gov (United States)

Witts, James D.; Newton, Robert J.; Mills, Benjamin J. W.; Wignall, Paul B.; Bottrell, Simon H.; Hall, Joanna L. O.; Francis, Jane E.; Alistair Crame, J.

2018-06-01

The Cretaceous-Paleogene (K-Pg) mass extinction event 66 million years ago led to large changes to the global carbon cycle, primarily via a decrease in primary or export productivity of the oceans. However, the effects of this event and longer-term environmental changes during the Late Cretaceous on the global sulfur cycle are not well understood. We report new carbonate associated sulfate (CAS) sulfur isotope data derived from marine macrofossil shell material from a highly expanded high latitude Maastrichtian to Danian (69-65.5 Ma) succession located on Seymour Island, Antarctica. These data represent the highest resolution seawater sulfate record ever generated for this time interval, and are broadly in agreement with previous low-resolution estimates for the latest Cretaceous and Paleocene. A vigorous assessment of CAS preservation using sulfate oxygen, carbonate carbon and oxygen isotopes and trace element data, suggests factors affecting preservation of primary seawater CAS isotopes in ancient biogenic samples are complex, and not necessarily linked to the preservation of original carbonate mineralogy or chemistry. Primary data indicate a generally stable sulfur cycle in the early-mid Maastrichtian (69 Ma), with some fluctuations that could be related to increased pyrite burial during the 'mid-Maastrichtian Event'. This is followed by an enigmatic +4‰ increase in δ34SCAS during the late Maastrichtian (68-66 Ma), culminating in a peak in values in the immediate aftermath of the K-Pg extinction which may be related to temporary development of oceanic anoxia in the aftermath of the Chicxulub bolide impact. There is no evidence of the direct influence of Deccan volcanism on the seawater sulfate isotopic record during the late Maastrichtian, nor of a direct influence by the Chicxulub impact itself. During the early Paleocene (magnetochron C29R) a prominent negative excursion in seawater δ34S of 3-4‰ suggests that a global decline in organic carbon burial

The carbon cycle in a land surface model: modelling, validation and implementation at a global scale; Cycle du carbone dans un modele de surface continentale: modelisation, validation et mise en oeuvre a l'echelle globale

Energy Technology Data Exchange (ETDEWEB)

Gibelin, A L

2007-05-15

ISBA-A-gs is an option of the CNRM land surface model ISBA which allows for the simulation of carbon exchanges between the terrestrial biosphere and the atmosphere. The model was implemented for the first time at the global scale as a stand-alone model. Several global simulations were performed to assess the sensitivity of the turbulent fluxes and Leaf Area Index to a doubling of the CO{sub 2} atmospheric concentration, and to the climate change simulated by the end of the 21. century. In addition, a new option of ISBA, referred to as ISBA-CC, was developed in order to simulate a more detailed ecosystem respiration by separating the autotrophic respiration and the heterotrophic respiration. The vegetation dynamics and the carbon fluxes were validated at a global scale using satellite datasets, and at a local scale using data from 26 sites of the FLUXNET network. All these results show that the model is sufficiently realistic to be coupled with a general circulation model, in order to account for interactions between the terrestrial biosphere, the atmosphere and the carbon cycle. (author)

Global carbon cycle and possible disturbances due to man's interventions

Energy Technology Data Exchange (ETDEWEB)

Pankrath, J

1979-01-01

Global atmospheric CO/sub 2/ concentration has increased since the beginning of reliable monitoring in 1958 at a mean rate of about 0.9 ppM CO/sub 2//y. Now, atmospheric, CO/sub 2/ concentration is at 330 ppM. From about 1860 up to 1974, man's intervention in the global carbon cycle caused a likely increase of 76.6 x 10/sup 15/ g C, corresponding to 36 ppM CO/sub 2/ in the atmosphere, if a preindustrial content of 294 ppM CO/sub 2/ or 625.3 x 10/sup 15/ g C is adopted to be valid. A further rise of atmospheric CO/sub 2/ seems to be inevitable and probably will be responsible for a climatic warming in the next several decades; therefore, a global examination of carbon reservoirs and carbon fluxes has been undertaken to determine their storage capacity for excess carbon which originated mainly from burning of fossil fuels and from land clearing. During 1860 to 1974 about 136 x 10/sup 15/ g C have been emitted into the atmosphere by fossil fuel combustion and cement production. At present, the emission rate is about 5 x 10/sup 15/ g C/y. The worldwide examination of carbon release, primarily by deforestation and soil cultivation since 1860, is estimated to be about 120 x 10/sup 15/ g C. The net transfer of carbon to the atmosphere owing to man's interference with the biosphere is now believed to be about 2.4 x 10/sup 15/ g C/y. An oceanic uptake of rougly 179 x 10/sup 15/ g C since 1860 is open to discussion. According to the chemical buffering of sea surface water only about 35.5 x 10/sup 15/ g C could have been absorbed. It is argued, however, that oceanic circulations might have been more effective in removing atmospheric excess carbon of anthropogenic origin.

Globalization of the nuclear fuel cycle

Energy Technology Data Exchange (ETDEWEB)

Rougeau, J.P. [Cogema, Corporate Strategy and International Development, Velizy (France)

1996-07-01

The article deals with the increased scale and sophistication of the markets in the nuclear fuel cycle, with the increased vulnerability to outside pressures, and with changes in the decision process.

Absorbability of calcium from calcium-bound phosphoryl oligosaccharides in comparison with that from various calcium compounds in the rat ligated jejunum loop.

Science.gov (United States)

To-o, Kenji; Kamasaka, Hiroshi; Nishimura, Takahisa; Kuriki, Takashi; Saeki, Shigeru; Nakabou, Yukihiro

2003-08-01

Calcium-bound phosphoryl oligosaccharides (POs-Ca) were prepared from potato starch. Their solubility and in situ absorbability as a calcium source were investigated by comparing with the soluble calcium compounds, calcium chloride and calcium lactate, or insoluble calcium compounds, calcium carbonate and dibasic calcium phosphate. The solubility of POs-Ca was as high as that of calcium chloride and about 3-fold higher than that of calcium lactate. An in situ experiment showed that the intestinal calcium absorption rate of POs-Ca was almost comparable with that of the soluble calcium compounds, and was significantly higher (pcalcium groups. Moreover, the total absorption rate of a 1:1 mixture of the calcium from POs-Ca and a whey mineral complex (WMC) was significantly higher (psoluble calcium source with relatively high absorption in the intestinal tract.

Uncertainty propagation in life cycle assessment of biodiesel versus diesel: global warming and non-renewable energy.

Science.gov (United States)

Hong, Jinglan

2012-06-01

Uncertainty information is essential for the proper use of life cycle assessment and environmental assessments in decision making. To investigate the uncertainties of biodiesel and determine the level of confidence in the assertion that biodiesel is more environmentally friendly than diesel, an explicit analytical approach based on the Taylor series expansion for lognormal distribution was applied in the present study. A biodiesel case study demonstrates the probability that biodiesel has a lower global warming and non-renewable energy score than diesel, that is 92.3% and 93.1%, respectively. The results indicate the level of confidence in the assertion that biodiesel is more environmentally friendly than diesel based on the global warming and non-renewable energy scores. Copyright © 2011 Elsevier Ltd. All rights reserved.

Role of sarcoplasmic reticulum calcium in development of secondary calcium rise and early afterdepolarizations in long QT syndrome rabbit model.

Directory of Open Access Journals (Sweden)

Po-Cheng Chang

Full Text Available L-type calcium current reactivation plays an important role in development of early afterdepolarizations (EADs and torsades de pointes (TdP. Secondary intracellular calcium (Cai rise is associated with initiation of EADs.To test whether inhibition of sarcoplasmic reticulum (SR Ca2+ cycling suppresses secondary Cai rise and genesis of EADs.Langendorff perfusion and dual voltage and Cai optical mapping were conducted in 10 rabbit hearts. Atrioventricular block (AVB was created by radiofrequency ablation. After baseline studies, E4031, SR Ca2+ cycling inhibitors (ryanodine plus thapsigargin and nifedipine were then administrated subsequently, and the protocols were repeated.At baseline, there was no spontaneous or pacing-induced TdP. After E4031 administration, action potential duration (APD was significantly prolonged and the amplitude of secondary Cai rise was enhanced, and 7 (70% rabbits developed spontaneous or pacing-induced TdP. In the presence of ryanodine plus thapsigargin, TdP inducibility was significantly reduced (2 hearts, 20%, p = 0.03. Although APD was significantly prolonged (from 298 ± 30 ms to 457 ± 75 ms at pacing cycle length of 1000 m, p = 0.007 by ryanodine plus thapsigargin, the secondary Cai rise was suppressed (from 8.8 ± 2.6% to 1.2 ± 0.9%, p = 0.02. Nifedipine inhibited TdP inducibility in all rabbit hearts.In this AVB and long QT rabbit model, inhibition of SR Ca2+ cycyling reduces the inducibility of TdP. The mechanism might be suppression of secondary Cai rise and genesis of EADs.

Alternative ORC bottoming cycles FOR combined cycle power plants

International Nuclear Information System (INIS)

Chacartegui, R.; Sanchez, D.; Munoz, J.M.; Sanchez, T.

2009-01-01

In this work, low temperature Organic Rankine Cycles are studied as bottoming cycle in medium and large scale combined cycle power plants. The analysis aims to show the interest of using these alternative cycles with high efficiency heavy duty gas turbines, for example recuperative gas turbines with lower gas turbine exhaust temperatures than in conventional combined cycle gas turbines. The following organic fluids have been considered: R113, R245, isobutene, toluene, cyclohexane and isopentane. Competitive results have been obtained for toluene and cyclohexane ORC combined cycles, with reasonably high global efficiencies. The paper is structured in four main parts. A review of combined cycle and ORC cycle technologies is presented, followed by a thermodynamic analysis of combined cycles with commercial gas turbines and ORC low temperature bottoming cycles. Then, a parametric optimization of an ORC combined cycle plant is performed in order to achieve a better integration between these two technologies. Finally, some economic considerations related to the use of ORC in combined cycles are discussed.

Get Enough Calcium

Science.gov (United States)

... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... women, don't get enough calcium. How much calcium do I need every day? Women: If you ...

The Effects of Dietary Calcium and/or Iron Deficiency upon Murine Intestinal Calcium Binding Protein Activity and Calcium Absorption

OpenAIRE

McDonald, Catherine M.

1980-01-01

Iron deficiency has been shown to impair calcium absorption, leading to decreased bone mass. Vitamin D3-dependent calcium binding protein (CaBP) has been demonstrated to be necessary for the active transport of calcium in the intestine of numerous species. Iron deficiency might affect the activity of the calcium binding protein. Four experimental diets were formulated as follows: Diet 1, iron adequate, calcium adequate; Diet 2, iron deficient, calcium adequate; Diet 3, iron adequate, calci...

Viral lysis of photosynthesizing microbes as a mechanism for calcium carbonate nucleation in seawater

Science.gov (United States)

Lisle, John T.; Robbins, Lisa L.

2016-01-01

Removal of carbon through the precipitation and burial of calcium carbonate in marine sediments constitutes over 70% of the total carbon on Earth and is partitioned between coastal and pelagic zones. The precipitation of authigenic calcium carbonate in seawater, however, has been hotly debated because despite being in a supersaturated state, there is an absence of persistent precipitation. One of the explanations for this paradox is the geochemical conditions in seawater cannot overcome the activation energy barrier for the first step in any precipitation reaction; nucleation. Here we show that virally induced rupturing of photosynthetic cyanobacterial cells releases cytoplasmic-associated bicarbonate at concentrations ~23-fold greater than in the surrounding seawater, thereby shifting the carbonate chemistry toward the homogenous nucleation of one or more of the calcium carbonate polymorphs. Using geochemical reaction energetics, we show the saturation states (Ω) in typical seawater for calcite (Ω = 4.3), aragonite (Ω = 3.1), and vaterite (Ω = 1.2) are significantly elevated following the release and diffusion of the cytoplasmic bicarbonate (Ωcalcite = 95.7; Ωaragonite = 68.5; Ωvaterite = 25.9). These increases in Ω significantly reduce the activation energy for nuclei formation thresholds for all three polymorphs, but only vaterite nucleation is energetically favored. In the post-lysis seawater, vaterite's nuclei formation activation energy is significantly reduced from 1.85 × 10−17 J to 3.85 × 10−20 J, which increases the nuclei formation rate from highly improbable (nucleation of calcium carbonate in seawater describes a mechanism through which the initial step in the production of carbonate sediments may proceed. It also presents an additional role of photosynthesizing microbes and their viruses in marine carbon cycles and reveals these microorganisms are a collective repository for concentrated and reactive dissolved inorganic carbon (DIC

Effects of diphosphonate on kidney calcium content and duodenal absorption of 45calcium

International Nuclear Information System (INIS)

Goulding, A.; Cameron, V.

1978-01-01

In rats the relationships between EHDP-induced changes in serum calcium concentration, kidney calcium content and duodenal transport of 45 calcium were studied. Body weights and kidney weights were similar in all groups. EHDP administration was associated with an increase in serum calcium concentration and kidney calcium content, and a decrease in duodenal 45 calcium transport. In the EHDP-treated rats, there was a significant negative correlation between kidney calcium concentration and duodenal 45 calcium transport but no correlation between either kidney calcium content and serum calcium concentration (r = 0.116) or between serum calcium concentration and duodenal 45 calcium transport (r = 0.02). Further experiments will be needed to determine whether the demonstrated increase in kidney calcium content induced by EHDP administration was the cause of, or was secondary to, inhibition of 1, 25(OH) 2 D 3 synthesis. (orig./AJ) [de

Effect of lowering dietary calcium intake on fractional whole body calcium retention

International Nuclear Information System (INIS)

Dawson-Hughes, B.; Stern, D.T.; Shipp, C.C.; Rasmussen, H.M.

1988-01-01

Although fractional calcium absorption is known to vary inversely with calcium intake, the extent and timing of individual hormonal and calcium absorption responses to altered calcium intake have not been defined. We measured fractional whole body retention of orally ingested 47 Ca, an index of calcium absorption, in nine normal women after they had eaten a 2000-mg calcium diet for 8 weeks and a 300-mg calcium diet for 1, 2, 4, and 8 weeks. After the diet change, serum intact PTH (32.2% increase; P = 0.005), serum 1,25-dihydroxyvitamin D [1,25-(OH)2D; 43.8% increase; P = 0.003], and fractional whole body calcium retention (42.8% increase; P = 0.004) increased within 1 week. Although the PTH and calcium retention responses remained fairly constant throughout the low calcium intake period, serum 1,25-(OH)2D concentrations declined toward baseline after week 1. Thus, the late increase in calcium retention may have resulted from calcium absorption that was independent of 1,25-(OH)2D stimulation

Structure-Property of Metal Organic Frameworks Calcium Terephthalates Anodes for Lithium-ion Batteries

International Nuclear Information System (INIS)

Wang, Liping; Mou, Chengxu; Sun, Yang; Liu, Wei; Deng, Qijiu; Li, Jingze

2015-01-01

Graphical Abstract: Effects of hydration water in calcium terephthalates anodes on the structure, operational voltage and electrochemical performance are systematically studied. Display Omitted -- Highlights: •Metal organic frameworks CaC 8 H 4 O 4 ·3H 2 O and CaC 8 H 4 O 4 are applied as anodes for lithium ion batteries. •Appearance of hydration water leads different crystallography structures and electrochemical performance. •Anhydrous CaC 8 H 4 O 4 has a spacious ordered layer structure, a higher Ca-O chemical bonding interaction and a higher transparent lithium ion diffusion coefficient, delivering a higher capacity, better cycling performance and rate performance than CaC 8 H 4 O 4 ·3H 2 O. -- Abstract: Metal organic frameworks have attracted considerable interest as electrode materials for lithium ion batteries. In this paper, the metal organic frameworks hydrated calcium terephthalate (CaC 8 H 4 O 4 ·3H 2 O) and anhydrous calcium terephthalate (CaC 8 H 4 O 4 ) as anodes for lithium ion batteries are comparatively studied. Crystallography and local chemical bond analysis are combined to interpret the structure-property of calcium terephthalates. Results show that the anhydrous CaC 8 H 4 O 4 has a spacious ordered layer structure and a higher Ca-O chemical bonding interaction, delivering a higher capacity, better cycling performance and rate performance than CaC 8 H 4 O 4 ·3H 2 O

A Novel Organic Rankine Cycle System with Improved Thermal Stability and Low Global Warming Fluids

Directory of Open Access Journals (Sweden)

Panesar Angad S

2014-07-01

Full Text Available This paper proposes a novel Organic Rankine Cycle (ORC system for long haul truck application. Rather than typical tail pipe heat recovery configurations, the proposed setup exploits the gaseous streams that are already a load on the engine cooling module. The system uses dual loops connected only by the Exhaust Gas Recirculation (EGR stream. A water blend study is conducted to identify suitable mixtures for the High Temperature (HT loop, while the Low Temperature (LT loop utilises a Low Global Warming (GWP Hydrofluoroether.

Greening the global phosphorus cycle

NARCIS (Netherlands)

Withers, Paul J.A.; Elser, James J.; Hilton, Julian; Ohtake, Hisao; Schipper, Willem J.; Dijk, Van Kimo C.

2015-01-01

The sustainability of global phosphorus (P) use is emerging as a major societal goal to secure future food, energy, and water security for a growing population. Phosphate rock (PR) is a critical raw material whose inefficiency of use is leading to widespread eutrophication and uncertainties about

Evaluating the effects of terrestrial ecosystems, climate and carbon dioxide on weathering over geological time: a global-scale process-based approach

Science.gov (United States)

Taylor, Lyla L.; Banwart, Steve A.; Valdes, Paul J.; Leake, Jonathan R.; Beerling, David J.

2012-01-01

Global weathering of calcium and magnesium silicate rocks provides the long-term sink for atmospheric carbon dioxide (CO2) on a timescale of millions of years by causing precipitation of calcium carbonates on the seafloor. Catchment-scale field studies consistently indicate that vegetation increases silicate rock weathering, but incorporating the effects of trees and fungal symbionts into geochemical carbon cycle models has relied upon simple empirical scaling functions. Here, we describe the development and application of a process-based approach to deriving quantitative estimates of weathering by plant roots, associated symbiotic mycorrhizal fungi and climate. Our approach accounts for the influence of terrestrial primary productivity via nutrient uptake on soil chemistry and mineral weathering, driven by simulations using a dynamic global vegetation model coupled to an ocean–atmosphere general circulation model of the Earth's climate. The strategy is successfully validated against observations of weathering in watersheds around the world, indicating that it may have some utility when extrapolated into the past. When applied to a suite of six global simulations from 215 to 50 Ma, we find significantly larger effects over the past 220 Myr relative to the present day. Vegetation and mycorrhizal fungi enhanced climate-driven weathering by a factor of up to 2. Overall, we demonstrate a more realistic process-based treatment of plant fungal–geosphere interactions at the global scale, which constitutes a first step towards developing ‘next-generation’ geochemical models. PMID:22232768

Constraints on Ca/Sr as a Proxy for Calcium in Forest Ecosystems

Science.gov (United States)

Hoff, C. J.; Hobbie, E. A.; Hallett, R.; Colpaert, J.; Bryce, J. G.

2004-05-01

Calcium is a key plant nutrient and important base cation in ecosystems. Our current efforts to quantify Ca cycling in ecosystems rely on indirect proxies, e.g., Ca/Sr or Sr isotopic systems (1). An important assumption in these applications is that the elemental ratio of calcium to strontium faithfully represents calcium cycling and that little fractionation occurs through biogeochemical and physiological processes. However, several researchers have reported variations in Ca/Sr, e.g. among different tree tissues (2) and during weathering processes (3), raising doubts about the suitability of the proxy. To address the question of reliability, we measured Ca/Sr values in a culture study in which Scots pines were grown at low or high nutrient supply rates (3% per day or 5% per day). Because mycorrhizal fungi are intimately involved in plant nutrient supply, plants were also grown either uncolonized or colonized with one of two different species of mycorrhizal fungi (Suillus luteus and Thelephora terrestris). Our preliminary results indicate that Ca/Sr values differ between high and low nutrient treatments, root and foliage, and mycorrhizal treatments. In individual seedlings, roots have lower Ca/Sr than foliage by absolute factors of 2-5. The magnitude of the effect is apparently determined by a combination of environmental factors including both the nutrient and mycorrhizal treatments. These results indicate that Ca and Sr are partitioned differently between nutrient and mycorrhizal treatments and between plant fractions despite the common nutrient broth and substrate. Thus, Ca/Sr values alone are not reliable tracers of Ca within an ecosystem because of partitioning of Ca and Sr during nutrient transport within the plant-mycorrhizal system. We are presently refining analytical techniques and conducting leachate experiments to improve the quantification of this Ca/Sr fractionation. We are also exploring the use of isotopic tracers to study calcium biogeochemical

The carbon cycle in a land surface model: modelling, validation and implementation at a global scale; Cycle du carbone dans un modele de surface continentale: modelisation, validation et mise en oeuvre a l'echelle globale

Energy Technology Data Exchange (ETDEWEB)

Gibelin, A.L

2007-05-15

ISBA-A-gs is an option of the CNRM land surface model ISBA which allows for the simulation of carbon exchanges between the terrestrial biosphere and the atmosphere. The model was implemented for the first time at the global scale as a stand-alone model. Several global simulations were performed to assess the sensitivity of the turbulent fluxes and Leaf Area Index to a doubling of the CO{sub 2} atmospheric concentration, and to the climate change simulated by the end of the 21. century. In addition, a new option of ISBA, referred to as ISBA-CC, was developed in order to simulate a more detailed ecosystem respiration by separating the autotrophic respiration and the heterotrophic respiration. The vegetation dynamics and the carbon fluxes were validated at a global scale using satellite datasets, and at a local scale using data from 26 sites of the FLUXNET network. All these results show that the model is sufficiently realistic to be coupled with a general circulation model, in order to account for interactions between the terrestrial biosphere, the atmosphere and the carbon cycle. (author)

Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

Directory of Open Access Journals (Sweden)

Bading Hilmar

2007-07-01

Full Text Available Abstract Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nucleus from activity-induced cytoplasmic calcium transients in some cell types. Results Using laser-assisted uncaging of caged calcium compounds in defined sub-cellular domains, we show here that the nuclear compartment border does not represent a barrier for calcium signals in hippocampal neurons. Although passive diffusion of molecules between the cytosol and the nucleoplasm may be modulated through changes in conformational state of the nuclear pore complex, we found no evidence for a gating mechanism for calcium movement across the nuclear border. Conclusion Thus, the nuclear envelope does not spatially restrict calcium transients to the somatic cytosol but allows calcium signals to freely enter the cell nucleus to trigger genomic events.

Calcium hydroxide isotope effect in calcium isotope enrichment by ion exchange

International Nuclear Information System (INIS)

Jepson, B.E.; Shockey, G.C.

1984-01-01

The enrichment of calcium isotopes has been observed in ion-exchange chromatography with an aqueous phase of calcium hydroxide and a solid phase of sulfonic acid resin. The band front was exceedingly sharp as a result of the acid-base reaction occuring at the front of the band. Single-stage separation coefficients were found to be epsilon( 44 Ca/ 40 Ca) = 11 x 10 -4 and epsilon( 48 Ca/ 40 Ca) = 18 x 10 -4 . The maximum column separation factors achieved were 1.05 for calcium-44 and 1.09 for calcium-48 with the heavy isotopes enriching in the fluid phase. The calcium isotope effect between fully hydrated aqueous calcium ions and undissociated aqueous calcium hydroxide was estimated. For the calcium-44/40 isotope pair the separation coefficient was 13 x 10 -4 . 20 references, 2 figures

The response of amino acid cycling to global change across multiple biomes: Feedbacks on soil nitrogen availability

Science.gov (United States)

Brzostek, E. R.; Finzi, A. C.

2010-12-01

The cycling of organic nitrogen (N) in soil links soil organic matter decomposition to ecosystem productivity. Amino acids are a key pool of organic N in the soil, whose cycling is sensitive to alterations in microbial demand for carbon and N. Further, the amino acids released from the breakdown of protein by proteolytic enzymes are an important source of N that supports terrestrial productivity. The objective of this study was to measure changes in amino acid cycling in response to experimental alterations of precipitation and temperature in twelve global change experiments during the 2009 growing season. The study sites ranged from arctic tundra to xeric grasslands. The treatments experimentally increased temperature, increased or decreased precipitation, or some combination of both factors. The response of amino acid cycling to temperature and precipitation manipulations tended to be site specific, but the responses could be placed into a common framework. Changes in soil moisture drove a large response in amino acid cycling. Precipitation augmentation in xeric and mesic sites increased both amino acid pool sizes and production. However, treatments that decreased precipitation drove decreases in amino acid cycling in xeric sites, but led to increases in amino acid cycling in more mesic sites. Across sites, the response to soil warming was horizon specific. Amino acid cycling in organic rich horizons responded positively to warming, while negative responses were exhibited in lower mineral soil horizons. The variable response likely reflects a higher availability of protein substrate to sustain high rates of proteolytic enzyme activity in organic rich horizons. Overall, these results suggest that soil moisture and the availability of protein substrate may be important factors that mediate the response of amino acid cycling to predicted increases in soil temperatures.

Calcium

Science.gov (United States)

... You can get decent amounts of calcium from baked beans, navy beans, white beans, and others. Canned fish. You're in luck if you like sardines and canned salmon with bones. Almond milk. Working Calcium Into Your ...

Influence of dietary calcium on bone calcium utilization

International Nuclear Information System (INIS)

Farmer, M.; Roland, D.A. Sr.; Clark, A.J.

1986-01-01

In Experiment 1, 10 microCi 45 Ca/day were administered to 125 hens for 10 days. Hens were then allocated to five treatments with calcium levels ranging from .08 to 3.75% of the diet. In Experiment 2, hens with morning oviposition times were randomly allocated to 11 treatments that were periods of time postoviposition ranging from 6 hr to 24 hr, in 2-hr increments (Experiment 2). At the end of each 2-hr period, eggs from 25 hens were removed from the uterus. The 18-, 20-, and 22-hr treatments were replicated three times. In Experiment 3, hens were fed either ad libitum or feed was withheld the last 5 or 6 hr before oviposition. In Experiment 4, hens were fed 10 microCi of 45 Ca for 15 days to label skeletal calcium. Hens were divided into two groups and fed a .08 or 3.75% calcium diet for 2 days. On the second day, 25 hens fed the 3.75% calcium diet were intubated with 7 g of the same diet containing .5 g calcium at 1700, 2100, 0100, 0500, and 0700 hr. The measurements used were egg weight, shell weight, and 45 Ca content of the egg shell. Results indicated a significant linear or quadratic regression of dietary calcium levels on 45 Ca accumulation in eggshells and eggshell weight (Experiment 1). As the calcium level of the diet increased, eggshell weight increased and 45 Ca recovery decreased. Utilization of skeletal calcium for shell formation ranged from 28 to 96%. In Experiment 2, the rate of shell calcification was not constant throughout the calcification process but varied significantly

Calcium D-saccharate

DEFF Research Database (Denmark)

Garcia, André Castilho; Hedegaard, Martina Vavrusova; Skibsted, Leif Horsfelt

2016-01-01

Molar conductivity of saturated aqueous solutions of calcium d-saccharate, used as a stabilizer of beverages fortified with calcium d-gluconate, increases strongly upon dilution, indicating complex formation between calcium and d-saccharate ions, for which, at 25 °C, Kassoc = 1032 ± 80, ΔHassoc......° = -34 ± 6 kJ mol-1, and ΔSassoc° = -55 ± 9 J mol-1 K-1, were determined electrochemically. Calcium d-saccharate is sparingly soluble, with a solubility product, Ksp, of (6.17 ± 0.32) × 10-7 at 25 °C, only moderately increasing with the temperature: ΔHsol° = 48 ± 2 kJ mol-1, and ΔSassoc° = 42 ± 7 J mol-1...... K-1. Equilibria in supersaturated solutions of calcium d-saccharate seem only to adjust slowly, as seen from calcium activity measurements in calcium d-saccharate solutions made supersaturated by cooling. Solutions formed by isothermal dissolution of calcium d-gluconate in aqueous potassium d...

Does the correlation between solar cycle lengths and Northern Hemisphere land temperatures rule out any significant global warming from greenhouse gases?

DEFF Research Database (Denmark)

Laut, Peter; Gundermann, Jesper

1998-01-01

Since the discovery of a striking correlation between solar cycle lengths and Northern Hemisphere land temperatures there have been widespread speculations as to whether these findings would rule out any significant contributions to global warming from the enhanced concentrations of greenhouse...... gases. The present analysis shows that a similar degree of correlation is obtained when testing the solar data against a couple of fictitious temperature series representing different global warming trends. Therefore, the correlation cannot be used to estimate the magnitude of a possible contribution...... to global warming from human activities, nor to rule out a sizable contribution from that source....

Highly Stable Aqueous Zinc-ion Storage Using Layered Calcium Vanadium Oxide Bronze Cathode

KAUST Repository

Xia, Chuan; Guo, Jing; Li, Peng; Zhang, Xixiang; Alshareef, Husam N.

2018-01-01

Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn2+ intercalation chemistry, stand out as they can employ high-capacity Zn metal as anode material. Herein, we report a layered calcium vanadium oxide bronze as cathode material for aqueous Zn batteries. For the storage of Zn2+ ions in aqueous electrolyte, we demonstrate that calcium based bronze structure can deliver a high capacity of 340 mAh g-1 at 0.2 C, good rate capability and very long cycling life (96% retention after 3000 cycles at 80 C). Further, we investigate the Zn2+ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 Wh kg-1 at a power density of 53.4 W kg-1.

Highly Stable Aqueous Zinc-ion Storage Using Layered Calcium Vanadium Oxide Bronze Cathode

KAUST Repository

Xia, Chuan

2018-02-12

Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn2+ intercalation chemistry, stand out as they can employ high-capacity Zn metal as anode material. Herein, we report a layered calcium vanadium oxide bronze as cathode material for aqueous Zn batteries. For the storage of Zn2+ ions in aqueous electrolyte, we demonstrate that calcium based bronze structure can deliver a high capacity of 340 mAh g-1 at 0.2 C, good rate capability and very long cycling life (96% retention after 3000 cycles at 80 C). Further, we investigate the Zn2+ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 Wh kg-1 at a power density of 53.4 W kg-1.

Simulation of global sulfate distribution and the influence of effective cloud drop radii with a coupled photochemistry-sulfur cycle model

NARCIS (Netherlands)

Roelofs, G.J.; Lelieveld, J.; Ganzeveld, L.N.

1998-01-01

A sulfur cycle model is coupled to a global chemistry-climate model. The simulated surface sulfate concentrations are generally within a factor of 2 of observed concentrations, and display a realistic seasonality for most background locations. However, the model tends to underestimate sulfate and

Inter-model variability and biases of the global water cycle in CMIP3 coupled climate models

International Nuclear Information System (INIS)

Liepert, Beate G; Previdi, Michael

2012-01-01

Observed changes such as increasing global temperatures and the intensification of the global water cycle in the 20th century are robust results of coupled general circulation models (CGCMs). In spite of these successes, model-to-model variability and biases that are small in first order climate responses, however, have considerable implications for climate predictability especially when multi-model means are used. We show that most climate simulations of the 20th and 21st century A2 scenario performed with CMIP3 (Coupled Model Inter-comparison Project Phase 3) models have deficiencies in simulating the global atmospheric moisture balance. Large biases of only a few models (some biases reach the simulated global precipitation changes in the 20th and 21st centuries) affect the multi-model mean global moisture budget. An imbalanced flux of −0.14 Sv exists while the multi-model median imbalance is only −0.02 Sv. Moreover, for most models the detected imbalance changes over time. As a consequence, in 13 of the 18 CMIP3 models examined, global annual mean precipitation exceeds global evaporation, indicating that there should be a ‘leaking’ of moisture from the atmosphere whereas for the remaining five models a ‘flooding’ is implied. Nonetheless, in all models, the actual atmospheric moisture content and its variability correctly increases during the course of the 20th and 21st centuries. These discrepancies therefore imply an unphysical and hence ‘ghost’ sink/source of atmospheric moisture in the models whose atmospheres flood/leak. The ghost source/sink of moisture can also be regarded as atmospheric latent heating/cooling and hence as positive/negative perturbation of the atmospheric energy budget or non-radiative forcing in the range of −1 to +6 W m −2 (median +0.1 W m −2 ). The inter-model variability of the global atmospheric moisture transport from oceans to land areas, which impacts the terrestrial water cycle, is also quite high and ranges

Estimation of presynaptic calcium currents and endogenous calcium buffers at the frog neuromuscular junction with two different calcium fluorescent dyes.

Science.gov (United States)

Samigullin, Dmitry; Fatikhov, Nijaz; Khaziev, Eduard; Skorinkin, Andrey; Nikolsky, Eugeny; Bukharaeva, Ellya

2014-01-01

At the frog neuromuscular junction, under physiological conditions, the direct measurement of calcium currents and of the concentration of intracellular calcium buffers-which determine the kinetics of calcium concentration and neurotransmitter release from the nerve terminal-has hitherto been technically impossible. With the aim of quantifying both Ca(2+) currents and the intracellular calcium buffers, we measured fluorescence signals from nerve terminals loaded with the low-affinity calcium dye Magnesium Green or the high-affinity dye Oregon Green BAPTA-1, simultaneously with microelectrode recordings of nerve-action potentials and end-plate currents. The action-potential-induced fluorescence signals in the nerve terminals developed much more slowly than the postsynaptic response. To clarify the reasons for this observation and to define a spatiotemporal profile of intracellular calcium and of the concentration of mobile and fixed calcium buffers, mathematical modeling was employed. The best approximations of the experimental calcium transients for both calcium dyes were obtained when the calcium current had an amplitude of 1.6 ± 0.08 pA and a half-decay time of 1.2 ± 0.06 ms, and when the concentrations of mobile and fixed calcium buffers were 250 ± 13 μM and 8 ± 0.4 mM, respectively. High concentrations of endogenous buffers define the time course of calcium transients after an action potential in the axoplasm, and may modify synaptic plasticity.

Environments of ocean and primary productivity during the late Quaternary. Millenial-scale large and abrupt climatic changes (global system dynamics in response to Dansgaard-Oeschger cycles); Daiyonki koki no kaiyo kankyo to seibutsu seisan. Suhyaku-susennen scale no kyugekina kiko hendo (Dansgaard-Oeschger cycle ni taisuru chikyu system no oto)

Energy Technology Data Exchange (ETDEWEB)

Tada, R. [The University of Tokyo, Tokyo (Japan)

1998-04-25

Abrupt and steep climate changes of the millennial scale as represented by the Dansgaard-Oeschger cycle (D-O cycle) and the behavior of the global surface layer system in their wake are outlined. The D-DO cycle is the abrupt and steep climate changes that are recorded in the Greenland continental ice sheet, and is grasped most typically as changes in the oxygen isotopic ratio in the ice. Studies reveal that the D-O cycle is a global episode that accompanied interaction between various subsystems constituting the global surface layer system. It is believed that in the D-O cycle there were changes not only in temperature but also in aridity/moisture and in the sea level, and probabilities are high that there was a great local variation in the way the changes took effect. The possibility has now become lower that the D-O cycle occurred in the interglacial epoch in the high latitude belt in the northern hemisphere, yet it remains likely that the climate changes driving the D-O cycle continued in the low latitude belt. 57 refs., 8 figs.

Dietary Calcium Intake in Sample of School Age Children in City of Rabat, Morocco

Directory of Open Access Journals (Sweden)

Amina Bouziani

2018-01-01

Full Text Available Calcium is an important mineral playing a vital role to maintain bone health. Calcium intake is considered as one of the most important determinants to assess the calcium status and to evaluate the calcium deficiency in the human body. Our study aims at estimating calcium intake in a sample of children and adolescent to be used in the global strategy to reduce calcium deficiency disorders in Morocco. Thus, 131 children and adolescents were recruited from public schools at Rabat and its regions in the framework of a descriptive cross-sectional study. For each participant, anthropometric parameters were measured. Calcium status was assessed by 24 h dietary recall. Food frequency questionnaire was used to evaluate children’s nutritional habits and to assess the consumption of calcium-rich food. Overall, the mean calcium intake was 522.0 ± 297.0 mg/day, and 85.5% of subjects highlighted calcium deficiency, with no significant difference between boys and girls. Calcium intake was significantly different according to age groups, and high consumption of calcium was found in subjects aged from 14 to 18 years (776.86 ±290.07 mg/day, giving evidence of the low calcium status of the studied population. Daily food intake and food frequency analysis showed that bread, vegetables, and fruits are the most consumed food and the main source of daily calcium intake. Consumption of dairy products, considered as the best source of calcium, is lower and represents only 14% of total calcium intake. Our study clearly showed that calcium status is very lower in Moroccan children and adolescents and a large proportion of this population have inadequate calcium intake. Hence, there’s an urgent need of specific strategies, including children sensitisation and nutritional education, to increase calcium intake and therefore reduce calcium deficiency disorders impacting the whole body during childhood and in adult age.

Viral lysis of photosynthesizing microbes as a mechanism for calcium carbonate nucleation in seawater

Science.gov (United States)

Lisle, John T.; Robbins, Lisa L.

2016-01-01

Removal of carbon through the precipitation and burial of calcium carbonate in marine sediments constitutes over 70% of the total carbon on Earth and is partitioned between coastal and pelagic zones. The precipitation of authigenic calcium carbonate in seawater, however, has been hotly debated because despite being in a supersaturated state, there is an absence of persistent precipitation. One of the explanations for this paradox is the geochemical conditions in seawater cannot overcome the activation energy barrier for the first step in any precipitation reaction; nucleation. Here we show that virally induced rupturing of photosynthetic cyanobacterial cells releases cytoplasmic-associated bicarbonate at concentrations ~23-fold greater than in the surrounding seawater, thereby shifting the carbonate chemistry toward the homogenous nucleation of one or more of the calcium carbonate polymorphs. Using geochemical reaction energetics, we show the saturation states (Ω) in typical seawater for calcite (Ω = 4.3), aragonite (Ω = 3.1), and vaterite (Ω = 1.2) are significantly elevated following the release and diffusion of the cytoplasmic bicarbonate (Ωcalcite = 95.7; Ωaragonite = 68.5; Ωvaterite = 25.9). These increases in Ω significantly reduce the activation energy for nuclei formation thresholds for all three polymorphs, but only vaterite nucleation is energetically favored. In the post-lysis seawater, vaterite's nuclei formation activation energy is significantly reduced from 1.85 × 10−17 J to 3.85 × 10−20 J, which increases the nuclei formation rate from highly improbable (seawater describes a mechanism through which the initial step in the production of carbonate sediments may proceed. It also presents an additional role of photosynthesizing microbes and their viruses in marine carbon cycles and reveals these microorganisms are a collective repository for concentrated and reactive dissolved inorganic carbon (DIC) that is currently not accounted for

Research of calcium oxide hydration in calcium nitrate solutions

Directory of Open Access Journals (Sweden)

M.A. Oliynyk

2016-09-01

Full Text Available Mineral fertilizers are one of the important factors of agriculture intensification and increasing of food products quantity. The volume of fertilizers production and its domestic consumption in Ukraine indicate that nitrogen fertilizer using only comes nearer to the required number of science-based. One of the most widespread artificial fertilizers is the calcium nitrate. Aim: The aim is to study and theoretically substantiate the processes occurring in the preparation of suspensions of calcium hydroxide Са(ОН2 in solution of calcium nitrate Ca(NО32. Materials and Methods: The technical calcium oxide (quicklime DSTU BV.2.7-90-99, solutions of calcium nitrate of 15, 20, 25, 30, 35 and 40% Ca(NО32 concentrations were used in the work. The content of lime in the preparation of a suspension in the solution changed (in terms of calcium oxide CaO from 150 g/dm3 to the maximum possible. Each of these solutions saturated at 40°С in lime to maximum concentration. Suitable for use in these experiments and in the technology of calcium nitrate obtaining are considered the solutions (suspensions that within 12 hours did not lose their mobility (transportability. Results: The experimental results show that increasing of the concentration of calcium nitrate in solution within the range 15...40%, the amount of lime that you can put into the solution without loss of transportability decreases. Further increasing of lime quantity in solutions concentrations causes to its solidifying, loss of mobility (transportability. Calculations showed that in the presence of calcium nitrate the solubility of Са(ОН2 is reduced nearly by order that can lead to the formation of calcium oxide CaO the solid phase Са(ОН2 on the surface, which also can form hydrogen bonds with the components of the solution. As the probability of formation of hydrogen bonds in solutions is high, there is a possibility of formation of clusters.

Bone mineral density and content during weight cycling in female rats: effects of dietary amylase-resistant starch

Directory of Open Access Journals (Sweden)

Jagpal Sugeet

2008-11-01

Full Text Available Abstract Background Although there is considerable evidence for a loss of bone mass with weight loss, the few human studies on the relationship between weight cycling and bone mass or density have differing results. Further, very few studies assessed the role of dietary composition on bone mass during weight cycling. The primary objective of this study was to determine if a diet high in amylase-resistant starch (RS2, which has been shown to increase absorption and balance of dietary minerals, can prevent or reduce loss of bone mass during weight cycling. Methods Female Sprague-Dawley (SD rats (n = 84, age = 20 weeks were randomly assigned to one of 6 treatment groups with 14 rats per group using a 2 × 3 experimental design with 2 diets and 3 weight cycling protocols. Rats were fed calcium-deficient diets without RS2 (controls or diets high in RS2 (18% by weight throughout the 21-week study. The weight cycling protocols were weight maintenance/gain with no weight cycling, 1 round of weight cycling, or 2 rounds of weight cycling. After the rats were euthanized bone mineral density (BMD and bone mineral content (BMC of femur were measured by dual energy X-ray absorptiometry, and concentrations of calcium, copper, iron, magnesium, manganese, and zinc in femur and lumbar vertebrae were determined by atomic absorption spectrophotometry. Results Rats undergoing weight cycling had lower femur BMC (p 2 had higher femur BMD (p 2-fed rats also had higher femur calcium (p Conclusion Weight cycling reduces bone mass. A diet high in RS2 can minimize loss of bone mass during weight cycling and may increase bone mass in the absence of weight cycling.

Production of precipitated calcium carbonate from calcium silicates and carbon dioxide

International Nuclear Information System (INIS)

Teir, Sebastian; Eloneva, Sanni; Zevenhoven, Ron

2005-01-01

The possibilities for reducing carbon dioxide emissions from the pulp and paper industry by calcium carbonation are presented. The current precipitated calcium carbonate (PCC) production uses mined, crushed calcium carbonate as raw materials. If calcium silicates were used instead, carbon dioxide emissions from the calcination of carbonates would be eliminated. In Finland, there could, thus, be a potential for eliminating 200 kt of carbon dioxide emissions per year, considering only the PCC used in the pulp and paper industry. A preliminary investigation of the feasibility to produce PCC from calcium silicates and the potential to replace calcium carbonate as the raw material was made. Calcium carbonate can be manufactured from calcium silicates by various methods, but only a few have been experimentally verified. The possibility and feasibility of these methods as a replacement for the current PCC production process was studied by thermodynamic equilibrium calculations using HSC software and process modelling using Aspen Plus[reg]. The results from the process modelling showed that a process that uses acetic acid for extraction of the calcium ions is a high potential option for sequestering carbon dioxide by mineral carbonation. The main obstacle seems to be the limited availability and relatively high price of wollastonite, which is a mineral with high calcium silicate content. An alternative is to use the more common, but also more complex, basalt rock instead

Estimation of presynaptic calcium currents and endogenous calcium buffers at the frog neuromuscular junction with two different calcium fluorescent dyes

Directory of Open Access Journals (Sweden)

Dmitry eSamigullin

2015-01-01

Full Text Available At the frog neuromuscular junction, under physiological conditions, the direct measurement of calcium currents and of the concentration of intracellular calcium buffers—which determine the kinetics of calcium concentration and neurotransmitter release from the nerve terminal—has hitherto been technically impossible. With the aim of quantifying both Ca2+ currents and the intracellular calcium buffers, we measured fluorescence signals from nerve terminals loaded with the low-affinity calcium dye Magnesium Green or the high-affinity dye Oregon Green BAPTA-1, simultaneously with microelectrode recordings of nerve-action potentials and end-plate currents. The action-potential-induced fluorescence signals in the nerve terminals developed much more slowly than the postsynaptic response. To clarify the reasons for this observation and to define a spatiotemporal profile of intracellular calcium and of the concentration of mobile and fixed calcium buffers, mathematical modeling was employed. The best approximations of the experimental calcium transients for both calcium dyes were obtained when the calcium current had an amplitude of 1.6 ± 0.08 рА and a half-decay time of 1.2 ± 0.06 ms, and when the concentrations of mobile and fixed calcium buffers were 250 ± 13 µM and 8 ± 0.4 mM, respectively. High concentrations of endogenous buffers define the time course of calcium transients after an action potential in the axoplasm, and may modify synaptic plasticity.

Calcium electroporation in three cell lines; a comparison of bleomycin and calcium, calcium compounds, and pulsing conditions

DEFF Research Database (Denmark)

Frandsen, Stine Krog; Gissel, Hanne; Hojman, Pernille

2013-01-01

offers several advantages over standard treatment options: calcium is inexpensive and may readily be applied without special precautions, as is the case with cytostatic drugs. Therefore, details on the use of calcium electroporation are essential for carrying out clinical trials comparing calcium...

Closed Cycle Solar Refrigeration with the Calcium Chloride System ...

African Journals Online (AJOL)

A closed cycle solid absorption intermittent refrigerator, using CaC12 absorbent and NH3 refrigerant, was constructed and tested to obtain the instantaneous and cumulative available overall COP. The combined collector/absorber/generator unit had double glazing of 1.14 m2 exposed areas. The system was fitted with a ...

Transcellular transport of calcium

Energy Technology Data Exchange (ETDEWEB)

Terepka, A R; Coleman, J R; Armbrecht, H J; Gunter, T E

1976-01-01

Studies of two calcium transporting epithelia, embryonic chick chorioallantoic membrane and the small intestine of rat and chick, have strongly suggested that the transfer of calcium across a cell involves processes distinctly different from intracellular calcium ion regulation. In the proposed model, transcellular calcium transport is considered as a specialized process developed only by certain cells in those tissues charged with bulk transfer of calcium. The overall effect of the endocytotic mechanism is bulk calcium movement across a cell, protection of mitochondria from exposure to high concentrations of calcium, and the avoidance of wide and potentially toxic fluctuations in cytosol ionic calcium levels. (MFB)

Global water cycle: geochemistry and environment

National Research Council Canada - National Science Library

Berner, Elizabeth Kay; Berner, Robert A

1987-01-01

.... The book provides an integrated approach to global geochemistry and environmental problems and introduces the reader to some fundamental concepts of geology, oceanography, meteorology, environmental...

eWaterCycle: A high resolution global hydrological model

Science.gov (United States)

van de Giesen, Nick; Bierkens, Marc; Drost, Niels; Hut, Rolf; Sutanudjaja, Edwin

2014-05-01

In 2013, the eWaterCycle project was started, which has the ambitious goal to run a high resolution global hydrological model. Starting point was the PCR-GLOBWB built by Utrecht University. The software behind this model will partially be re-engineered in order to enable to run it in a High Performance Computing (HPC) environment. The aim is to have a spatial resolution of 1km x 1km. The idea is also to run the model in real-time and forecasting mode, using data assimilation. An on-demand hydraulic model will be available for detailed flow and flood forecasting in support of navigation and disaster management. The project faces a set of scientific challenges. First, to enable the model to run in a HPC environment, model runs were analyzed to examine on which parts of the program most CPU time was spent. These parts were re-coded in Open MPI to allow for parallel processing. Different parallelization strategies are thinkable. In our case, it was decided to use watershed logic as a first step to distribute the analysis. There is rather limited recent experience with HPC in hydrology and there is much to be learned and adjusted, both on the hydrological modeling side and the computer science side. For example, an interesting early observation was that hydrological models are, due to their localized parameterization, much more memory intensive than models of sister-disciplines such as meteorology and oceanography. Because it would be deadly to have to swap information between CPU and hard drive, memory management becomes crucial. A standard Ensemble Kalman Filter (enKF) would, for example, have excessive memory demands. To circumvent these problems, an alternative to the enKF was developed that produces equivalent results. This presentation shows the most recent results from the model, including a 5km x 5km simulation and a proof of concept for the new data assimilation approach. Finally, some early ideas about financial sustainability of an operational global

Comparing the Effects of Yoga & Oral Calcium Administration in Alleviating Symptoms of Premenstrual Syndrome in Medical Undergraduates

Directory of Open Access Journals (Sweden)

Mehta Bharati

2016-09-01

Full Text Available Introduction: Medical undergraduates are heavily burdened by their curriculum. The females, in addition, suffer from vivid affective or somatic premenstrual syndrome (PMS symptoms such as bloating, mastalgia, insomnia, fatigue, mood swings, irritability, and depression. The present study was proposed to attenuate the symptoms of PMS by simple lifestyle measures like yoga and/or oral calcium. Methods: 65 medical female students (18-22 years with a regular menstrual cycle were asked to self-rate their symptoms, along with their severity, in a validated questionnaire for two consecutive menstrual cycles. Fifty-eight students were found to have PMS. Twenty girls were given yoga training (45 minutes daily, five days a week, for three months. Another group of 20 was given oral tablets of calcium carbonate daily (500 mg, for three months and rest 18 girl served as control group. Data were analyzed by SPSS ver.13 software. Results: The yoga and calcium groups showed a significant decrease in number and severity of premenstrual symptoms whereas in the control group there was not the significant difference. Conclusion: Encouraging a regular practice of yoga or taking a tablet of calcium daily in the medical schools can decrease the symptoms of premenstrual syndrome.

The changing global carbon cycle: Linking plant-soil carbon dynamics to global consequences

Science.gov (United States)

Chapin, F. S.; McFarland, J.; McGuire, David A.; Euskirchen, E.S.; Ruess, Roger W.; Kielland, K.

2009-01-01

Most current climate-carbon cycle models that include the terrestrial carbon (C) cycle are based on a model developed 40 years ago by Woodwell & Whittaker (1968) and omit advances in biogeochemical understanding since that time. Their model treats net C emissions from ecosystems as the balance between net primary production (NPP) and heterotrophic respiration (HR, i.e. primarily decomposition).

Impact of toothbrushing with a dentifrice containing calcium peroxide on enamel color and roughness.

Science.gov (United States)

Feitosa, Diala Aretha de Sousa; Borges, Boniek Castillo Dutra; Pinheiro, Fabio Henrique de Sa Leitao; Duarte, Rosangela Marques; Araujo, Renato Evangelista de; Braz, Rodivan; Santos, Maria Carmo Moreira da Silva; Montes, Marcos Antonio Japiassu Resende

2015-01-01

This in vitro study sought to evaluate both the bleaching potential and changes to average surface roughness (Ra) of enamel after brushing with a dentifrice. Fifty-four enamel specimens (4 x 4 x 2 mm) were divided into 3 groups (n = 18) and treated with 1 of 3 dentifrices: 1 with calcium peroxide, and 2 without. The samples were submitted to 20,000 brushing cycles. Color and Ra were measured before and after brushing. Although the Ra increased in all groups after brushing, only the dentifrice containing calcium peroxide resulted in an increase in reflectance.

Closing the Global Energy and Nutrient Cycles through Application of Biogas Residue to Agricultural Land – Potential Benefits and Drawback

Directory of Open Access Journals (Sweden)

Veronica Arthurson

2009-04-01

Full Text Available Anaerobic digestion is an optimal way to treat organic waste matter, resulting in biogas and residue. Utilization of the residue as a crop fertilizer should enhance crop yield and soil fertility, promoting closure of the global energy and nutrient cycles. Consequently, the requirement for production of inorganic fertilizers will decrease, in turn saving significant amounts of energy, reducing greenhouse gas emissions to the atmosphere, and indirectly leading to global economic benefits. However, application of this residue to agricultural land requires careful monitoring to detect amendments in soil quality at the early stages.

The Effects of Calcium-Vitamin D and Metformin on Polycystic Ovary Syndrome: A Pilot Study

Directory of Open Access Journals (Sweden)

Batool Rashidi

2009-06-01

Conclusion: The effects of metformin and calcium-vitamin D in regulating the menstrual cycle suggest that they could also be effective for the treatment of anovulation and oligomenorrhea, with possible consequences for pregnancy rates in PCOS patients.

Calcium hydroxide poisoning

Science.gov (United States)

Hydrate - calcium; Lime milk; Slaked lime ... Calcium hydroxide ... These products contain calcium hydroxide: Cement Limewater Many industrial solvents and cleaners (hundreds to thousands of construction products, flooring strippers, brick cleaners, cement ...

A model of the solar cycle driven by the dynamo action of the global convection in the solar convection zone

International Nuclear Information System (INIS)

Yoshimura, H.

1975-01-01

The dynamo equation which represents the longitudinally averaged magnetohydrodynamical action of the global convection influenced by the rotation in the solar convection zone is solved numerically to simulate the solar cycle as an initial boundary-value problem. The radial and latitudinal structure of the dynamo action is parametrized in accordance with the structure of the rotation, and of the global convection especially in such a way as to represent the presence of the two cells of the regeneration action in the radial direction in which the action has opposite signs, which is typical of the regeneration action of the global convection. A nonlinear process is included by assuming that part of the magnetic field energy is dissipated when the magnetic field strength exceeds some critical value; the formation of active regions and subsequent dissipations are thus simulated. By adjusting the parameters within a reasonable range, oscillatory solutions are obtained to simulate the solar cycle with the period of the right order of magnitude and with the patterns of evolution of the latitudinal distribution of the toroidal component of the magnetic field similar to the observed Butterfly Diagram of sunspots. The evolution of the latitudinal distribution of the radial component of the magnetic field shows patterns similar to the Butterfly Diagram, but having two branches of different polarity in each hemisphere. The development of the radial structure of the magnetic field associated with the solar cycle is presented. The importance of the poleward migrating branch of the Butterfly Diagram is emphasized in relation to the relative importance of the role of the latitudinal and radial shears of the differential rotation

Calcium carbonate production response to future ocean warming and acidification

Directory of Open Access Journals (Sweden)

A. J. Pinsonneault

2012-06-01

Full Text Available Anthropogenic carbon dioxide (CO₂ emissions are acidifying the ocean, affecting calcification rates in pelagic organisms, and thereby modifying the oceanic carbon and alkalinity cycles. However, the responses of pelagic calcifying organisms to acidification vary widely between species, contributing uncertainty to predictions of atmospheric CO₂ and the resulting climate change. At the same time, ocean warming caused by rising CO₂ is expected to drive increased growth rates of all pelagic organisms, including calcifiers. It thus remains unclear whether anthropogenic CO₂ emissions will ultimately increase or decrease pelagic calcification rates. Here, we assess the importance of this uncertainty by introducing a dependence of calcium carbonate (CaCO₃ production on calcite saturation state (Ω_CaCO3 in an intermediate complexity coupled carbon-climate model. In a series of model simulations, we examine the impact of several variants of this dependence on global ocean carbon cycling between 1800 and 3500 under two different CO₂ emissions scenarios. Introducing a calcification-saturation state dependence has a significant effect on the vertical and surface horizontal alkalinity gradients, as well as on the removal of alkalinity from the ocean through CaCO₃ burial. These changes result in an additional oceanic uptake of carbon when calcification depends on Ω_CaCO3 (of up to 270 Pg C, compared to the case where calcification does not depend on acidification. In turn, this response causes a reduction of global surface air temperature of up to 0.4 °C in year 3500. Different versions of the model produced varying results, and narrowing this range of uncertainty will require better understanding of both temperature and acidification effects on pelagic calcifiers. Nevertheless, our results suggest that alkalinity observations can be used

Kinetics of calcium sulfoaluminate formation from tricalcium aluminate, calcium sulfate and calcium oxide

International Nuclear Information System (INIS)

Li, Xuerun; Zhang, Yu; Shen, Xiaodong; Wang, Qianqian; Pan, Zhigang

2014-01-01

The formation kinetics of tricalcium aluminate (C 3 A) and calcium sulfate yielding calcium sulfoaluminate (C 4 A 3 $) and the decomposition kinetics of calcium sulfoaluminate were investigated by sintering a mixture of synthetic C 3 A and gypsum. The quantitative analysis of the phase composition was performed by X-ray powder diffraction analysis using the Rietveld method. The results showed that the formation reaction 3Ca 3 Al 2 O 6 + CaSO 4 → Ca 4 Al 6 O 12 (SO 4 ) + 6CaO was the primary reaction 4 Al 6 O 12 (SO 4 ) + 10CaO → 6Ca 3 Al 2 O 6 + 2SO 2 ↑ + O 2 ↑ primarily occurred beyond 1350 °C with an activation energy of 792 ± 64 kJ/mol. The optimal formation region for C 4 A 3 $ was from 1150 °C to 1350 °C and from 6 h to 1 h, which could provide useful information on the formation of C 4 A 3 $ containing clinkers. The Jander diffusion model was feasible for the formation and decomposition of calcium sulfoaluminate. Ca 2+ and SO 4 2− were the diffusive species in both the formation and decomposition reactions. -- Highlights: •Formation and decomposition of calcium sulphoaluminate were studied. •Decomposition of calcium sulphoaluminate combined CaO and yielded C 3 A. •Activation energy for formation was 231 ± 42 kJ/mol. •Activation energy for decomposition was 792 ± 64 kJ/mol. •Both the formation and decomposition were controlled by diffusion

Why Calcium? How Calcium Became the Best Communicator*

Science.gov (United States)

Carafoli, Ernesto; Krebs, Joachim

2016-01-01

Calcium carries messages to virtually all important functions of cells. Although it was already active in unicellular organisms, its role became universally important after the transition to multicellular life. In this Minireview, we explore how calcium ended up in this privileged position. Most likely its unique coordination chemistry was a decisive factor as it makes its binding by complex molecules particularly easy even in the presence of large excesses of other cations, e.g. magnesium. Its free concentration within cells can thus be maintained at the very low levels demanded by the signaling function. A large cadre of proteins has evolved to bind or transport calcium. They all contribute to buffer it within cells, but a number of them also decode its message for the benefit of the target. The most important of these “calcium sensors” are the EF-hand proteins. Calcium is an ambivalent messenger. Although essential to the correct functioning of cell processes, if not carefully controlled spatially and temporally within cells, it generates variously severe cell dysfunctions, and even cell death. PMID:27462077

Codissolution of calcium hydrogenphosphate and sodium hydrogencitrate in water. Spontaneous supersaturation of calcium citrate increasing calcium bioavailability

DEFF Research Database (Denmark)

Hedegaard, Martina Vavrusova; Danielsen, Bente Pia; Garcia, André Castilho

2018-01-01

The sparingly soluble calcium hydrogenphosphate dihydrate, co-dissolving in water during dissolution of freely soluble sodium hydrogencitrate sesquihydrate as caused by proton transfer from hydrogencitrate to hydrogenphosphate, was found to form homogenous solutions supersaturated by a factor up...... to 8 in calcium citrate tetrahydrate. A critical hydrogencitrate concentration for formation of homogeneous solutions was found to depend linearly on dissolved calcium hydrogenphosphate: [HCitr2-] = 14[CaHPO4] - 0.05 at 25 °C. The lag phase for precipitation of calcium citrate tetrahydrate......, as identified from FT-IR spectra, from these spontaneously formed supersaturated solutions was several hours, and the time to reach solubility equilibrium was several days. Initial calcium ion activity was found to be almost independent of the degree of supersaturation as determined electrochemically...

The Challenges of Developing a Framework for Global Water Cycle Monitoring and Prediction (Alfred Wegener Medal Lecture)

Science.gov (United States)

Wood, Eric F.

2014-05-01

The Global Earth Observation System of Systems (GEOSS) Water Strategy ("From Observations to Decisions") recognizes that "water is essential for ensuring food and energy security, for facilitating poverty reduction and health security, and for the maintenance of ecosystems and biodiversity", and that water cycle data and observations are critical for improved water management and water security - especially in less developed regions. The GEOSS Water Strategy has articulated a number of goals for improved water management, including flood and drought preparedness, that include: (i) facilitating the use of Earth Observations for water cycle observations; (ii) facilitating the acquisition, processing, and distribution of data products needed for effective management; (iii) providing expertise, information systems, and datasets to the global, regional, and national water communities. There are several challenges that must be met to advance our capability to provide near real-time water cycle monitoring, early warning of hydrological hazards (floods and droughts) and risk assessment under climate change, regionally and globally. Current approaches to monitoring and predicting hydrological hazards are limited in many parts of the world, and especially in developing countries where national capacity is limited and monitoring networks are inadequate. This presentation describes the developments at Princeton University towards a seamless monitoring and prediction framework at all time scales that allows for consistent assessment of water variability from historic to current conditions, and from seasonal and decadal predictions to climate change projections. At the center of the framework is an experimental, global water cycle monitoring and seasonal forecast system that has evolved out of regional and continental systems for the US and Africa. The system is based on land surface hydrological modeling that is driven by satellite remote sensing precipitation to predict

Calcium blood test

Science.gov (United States)

... page: //medlineplus.gov/ency/article/003477.htm Calcium blood test To use the sharing features on this page, please enable JavaScript. The calcium blood test measures the level of calcium in the blood. ...

Coral reef sedimentation on Rodrigues and the Western Indian Ocean and its impact on the carbon cycle.

Science.gov (United States)

Rees, Siwan A; Opdyke, Bradley N; Wilson, Paul A; Fifield, L Keith

2005-01-15

Coral reefs in the southwest Indian Ocean cover an area of ca. 18,530 km2 compared with a global reef area of nearly 300,000 km2. These regions are important as fishing grounds, tourist attractions and as a significant component of the global carbon cycle. The mass of calcium carbonate stored within Holocene neritic sediments is a number that we are only now beginning to quantify with any confidence, in stark contrast to the mass and sedimentation rates associated with pelagic calcium carbonate, which have been relatively well defined for decades. We report new data that demonstrate that the reefs at Rodrigues, like those at Reunion and Mauritius, only reached a mature state (reached sea level) by 2-3 ka: thousands of years later than most of the reefs in the Australasian region. Yet field observations show that the large lagoon at Rodrigues is already completely full of carbonate detritus (typical lagoon depth less than 1 m at low spring tide). The presence of aeolian dunes at Rodrigues indicates periodic exposure of past lagoons throughout the Pleistocene. The absence of elevated Pleistocene reef deposits on the island indicates that the island has not been uplifted. Most Holocene reefs are between 15 and 20 m in thickness and those in the southwest Indian Ocean appear to be consistent with this observation. We support the view that the CO2 flux associated with coral-reef growth acts as a climate change amplifier during deglaciation, adding CO2 to a warming world. southwest Indian Ocean reefs could have added 7-10% to this global flux during the Holocene.

The importance of vitamin D in maternal and child health: a global perspective.

Science.gov (United States)

Fiscaletti, M; Stewart, P; Munns, C F

2017-01-01

Vitamin D and calcium are important nutrients for skeletal growth and bone health. Children and pregnant women are particularly vulnerable to 25-hydroxy vitamin D deficiency (VDD). VDD, with or without dietary calcium deficiency, can lead to nutritional rickets (NR), osteomalacia, and disturbances in calcium homeostasis. Multiple studies have linked VDD to adverse health outcomes in both children and pregnant women that extend beyond bone health. VDD remains an important global public health concern, and an important differentiation must be made between the impact of VDD on children and adults. Reports of increased incidence of NR continue to emerge. NR is an entirely preventable condition, which could be eradicated in infants and children worldwide with adequate vitamin D and calcium supplementation. The desire and necessity to put in place systems for preventing this potentially devastating pediatric disease should not elicit dispute. VDD and NR are global public health issues that require a collaborative, multi-level approach for the implementation of feasible preventative strategies. This review highlights the history, risk factors, and controversies related to VDD during pregnancy and childhood with a particular focus on global NR prevention.

Calcium carbonate overdose

Science.gov (United States)

Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Products that contain calcium carbonate are certain: Antacids (Tums, Chooz) Mineral supplements Hand lotions Vitamin and mineral supplements Other products may also contain ...

Investigation of function similarities between the sarcoplasmic reticulum and platelet calcium-dependent adenosinetriphosphatases with the inhibitors quercetin and calmidazolium

International Nuclear Information System (INIS)

Fischer, T.H.; Campbell, K.P.; White, G.C. II

1987-01-01

The platelet and skeletal sarcoplasmic reticulum calcium-dependent adenosinetriphosphatases (Ca 2+ -ATPases) were functionally compared with respect to substrate activation by steady-state kinetic methods using the inhibitors quercetin and calmidazolium. Quercetin inhibited platelet and sarcoplasmic reticulum Ca 2+ -ATPase activities in a dose-dependent manner with IC 50 values of 25 and 10 μM, respectively. Calmidazolium also inhibited platelet and sarcoplasmic reticulum Ca 2+ -ATPase activities, with half-maximal inhibition measured at 5 and 4 μM, respectively. Both inhibitors also affected the [ 45 Ca] calcium transport activity of intact platelet microsomes at concentrations similar to those which reduced Ca 2+ -ATPase activity. These inhibitors were then used to examine substrate ligation by the platelet and sarcoplasmic reticulum calcium pump proteins. For both Ca 2+ -ATPase proteins, quercetin has an affinity for the E-Ca 2 (fully ligated with respect to calcium at the exterior high-affinity calcium binding sites, unligated with respect to ATP) conformational state of the protein that is approximately 10-fold grater than for other conformational states in the hydrolytic cycle. Quercetin can thus be considered a competitive inhibitor of the calcium pump proteins with respect to ATP. In contrast to the effect of quercetin, calmidazolium interacts with the platelet and sarcoplasmic reticulum Ca 2+ -ATPases in an uncompetitive manner. The dissociation constants for this inhibitor for the different conformational states of the calcium pump proteins were similar, indicating that calmidazolium has equal affinity for all of the reaction intermediates probed. These observations indicate that the substrate ligation processes are similar for the two pump proteins. This supports the concept that the hydrolytic cycles of the two proteins are comparable

Marine methane cycle simulations for the period of early global warming

Energy Technology Data Exchange (ETDEWEB)

Elliott, S.; Maltrud, M.; Reagan, M.T.; Moridis, G.J.; Cameron-Smith, P.J.

2011-01-02

Geochemical environments, fates, and effects are modeled for methane released into seawater by the decomposition of climate-sensitive clathrates. A contemporary global background cycle is first constructed, within the framework of the Parallel Ocean Program. Input from organics in the upper thermocline is related to oxygen levels, and microbial consumption is parameterized from available rate measurements. Seepage into bottom layers is then superimposed, representing typical seabed fluid flow. The resulting CH{sub 4} distribution is validated against surface saturation ratios, vertical sections, and slope plume studies. Injections of clathrate-derived methane are explored by distributing a small number of point sources around the Arctic continental shelf, where stocks are extensive and susceptible to instability during the first few decades of global warming. Isolated bottom cells are assigned dissolved gas fluxes from porous-media simulation. Given the present bulk removal pattern, methane does not penetrate far from emission sites. Accumulated effects, however, spread to the regional scale following the modeled current system. Both hypoxification and acidification are documented. Sensitivity studies illustrate a potential for material restrictions to broaden the perturbations, since methanotrophic consumers require nutrients and trace metals. When such factors are considered, methane buildup within the Arctic basin is enhanced. However, freshened polar surface waters act as a barrier to atmospheric transfer, diverting products into the deep return flow. Uncertainties in the logic and calculations are enumerated including those inherent in high-latitude clathrate abundance, buoyant effluent rise through the column, representation of the general circulation, and bacterial growth kinetics.

Marine methane cycle simulations for the period of early global warming

Science.gov (United States)

Elliott, Scott; Maltrud, Mathew; Reagan, Matthew; Moridis, George; Cameron-Smith, Philip

2011-03-01

Geochemical environments, fates, and effects are modeled for methane released into seawater by the decomposition of climate-sensitive clathrates. A contemporary global background cycle is first constructed, within the framework of the Parallel Ocean Program. Input from organics in the upper thermocline is related to oxygen levels, and microbial consumption is parameterized from available rate measurements. Seepage into bottom layers is then superimposed, representing typical seabed fluid flow. The resulting CH4 distribution is validated against surface saturation ratios, vertical sections, and slope plume studies. Injections of clathrate-derived methane are explored by distributing a small number of point sources around the Arctic continental shelf, where stocks are extensive and susceptible to instability during the first few decades of global warming. Isolated bottom cells are assigned dissolved gas fluxes from porous-media simulation. Given the present bulk removal pattern, methane does not penetrate far from emission sites. Accumulated effects, however, spread to the regional scale following the modeled current system. Both hypoxification and acidification are documented. Sensitivity studies illustrate a potential for material restrictions to broaden the perturbations, since methanotrophic consumers require nutrients and trace metals. When such factors are considered, methane buildup within the Arctic basin is enhanced. However, freshened polar surface waters act as a barrier to atmospheric transfer, diverting products into the deep return flow. Uncertainties in the logic and calculations are enumerated including those inherent in high-latitude clathrate abundance, buoyant effluent rise through the column, representation of the general circulation, and bacterial growth kinetics.

Global life cycle releases of engineered nanomaterials

International Nuclear Information System (INIS)

Keller, Arturo A.; McFerran, Suzanne; Lazareva, Anastasiya; Suh, Sangwon

2013-01-01

Engineered nanomaterials (ENMs) are now becoming a significant fraction of the material flows in the global economy. We are already reaping the benefits of improved energy efficiency, material use reduction, and better performance in many existing and new applications that have been enabled by these technological advances. As ENMs pervade the global economy, however, it becomes important to understand their environmental implications. As a first step, we combined ENM market information and material flow modeling to produce the first global assessment of the likely ENM emissions to the environment and landfills. The top ten most produced ENMs by mass were analyzed in a dozen major applications. Emissions during the manufacturing, use, and disposal stages were estimated, including intermediate steps through wastewater treatment plants and waste incineration plants. In 2010, silica, titania, alumina, and iron and zinc oxides dominate the ENM market in terms of mass flow through the global economy, used mostly in coatings/paints/pigments, electronics and optics, cosmetics, energy and environmental applications, and as catalysts. We estimate that 63–91 % of over 260,000–309,000 metric tons of global ENM production in 2010 ended up in landfills, with the balance released into soils (8–28 %), water bodies (0.4–7 %), and atmosphere (0.1–1.5 %). While there are considerable uncertainties in the estimates, the framework for estimating emissions can be easily improved as better data become available. The material flow estimates can be used to quantify emissions at the local level, as inputs for fate and transport models to estimate concentrations in different environmental compartments.

Alternative "global warming" metrics in life cycle assessment: a case study with existing transportation data.

Science.gov (United States)

Peters, Glen P; Aamaas, Borgar; T Lund, Marianne; Solli, Christian; Fuglestvedt, Jan S

2011-10-15

The Life Cycle Assessment (LCA) impact category "global warming" compares emissions of long-lived greenhouse gases (LLGHGs) using Global Warming Potential (GWP) with a 100-year time-horizon as specified in the Kyoto Protocol. Two weaknesses of this approach are (1) the exclusion of short-lived climate forcers (SLCFs) and biophysical factors despite their established importance, and (2) the use of a particular emission metric (GWP) with a choice of specific time-horizons (20, 100, and 500 years). The GWP and the three time-horizons were based on an illustrative example with value judgments and vague interpretations. Here we illustrate, using LCA data of the transportation sector, the importance of SLCFs relative to LLGHGs, different emission metrics, and different treatments of time. We find that both the inclusion of SLCFs and the choice of emission metric can alter results and thereby change mitigation priorities. The explicit inclusion of time, both for emissions and impacts, can remove value-laden assumptions and provide additional information for impact assessments. We believe that our results show that a debate is needed in the LCA community on the impact category "global warming" covering which emissions to include, the emission metric(s) to use, and the treatment of time.

Calcium: the molecular basis of calcium action in biology and medicine

National Research Council Canada - National Science Library

Pochet, Roland; Donato, Rosario

2000-01-01

... of Calcium Calcium Signalling in Excitable Cells Ca2+ Release in Muscle Cells by N. Macrez and J. Mironneau Calcium Signalling in Neurons Exemplified by Rat Sympathetic Ganglion Cells by S.J. M...

Calcium source (image)

Science.gov (United States)

Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...

Calcium ferrite formation from the thermolysis of calcium tris (maleato)

Indian Academy of Sciences (India)

For preparing calcium ferrite, calcium tris (maleato) ferrate(III) precursor was prepared by mixing aqueous solutions of iron(III) maleate, calcium maleate and maleic acid. Various physico-chemical techniques i.e. TG, DTG, DTA, Mössbauer, XRD, IR etc have been used to study the decomposition behaviour from ambient to ...

The effect of calcium phosphate nanoparticles on hormone production and apoptosis in human granulosa cells

Directory of Open Access Journals (Sweden)

Gao Li

2010-04-01

Full Text Available Abstract Objectives Although many nanomaterials are being used in academia, industry and daily life, there is little understanding about the effects of nanoparticles on the reproductive health of vertebral animals, including human beings. An experimental study was therefore performed here to explore the effect of calcium phosphate nanoparticles on both steroid hormone production and apoptosis in human ovarian granulosa cells. Methods Calcium phosphate nanoparticles uptaking was evaluated by transmission electron microscopy (TEM. The cell cycle was assessed with propidium iodide-stained cells (distribution of cells in G0/G1, S, and G2/M phases by flow cytometry. The pattern of cell death (necrosis and apoptosis was analyzed by flow cytometry with annexin V-FITC/PI staining. The expression of mRNAs encoding P450scc, P450arom and StAR were determined by RT-PCR. Progesterone and estradiol levels were measured by radioimmunoassay. Results TEM results confirmed that calcium phosphate nanoparticles could enter into granulosa cells, and distributed in the membranate compartments, including lysosome and mitochondria and intracellular vesicles. The increased percentage of cells in S phase when cultured with nanoparticles indicated that there was an arrest at the checkpoint from phase S-to-G2/M (from 6.28 +/- 1.55% to 11.18 +/- 1.73%, p Conclusion Calcium phosphate nanoparticles interfered with cell cycle of cultured human ovarian granulosa cells thus increasing cell apoptosis. This pilot study suggested that effects of nanoparticles on ovarian function should be extensively investigated.

The effect of habitat geology on calcium intake and calcium status of wild rodents.

Science.gov (United States)

Shore, R F; Balment, R J; Yalden, D W

1991-12-01

Calcium is essential for normal physiological function, reproduction and growth in mammals but its distribution in the natural environment is heterogeneous. Spatial variation in calcium soil content is especially marked in the Peak District, United Kingdom, where both calcium-rich limestone and calcium-poor gritstone rock types occur. Wood mice Apodemus sylvaticus (L) and bank voles Clethrionomys glareolus (Schreber 1780) from limestone areas had significantly higher calcium concentrations in stomach contents and in faeces compared with their counterparts from gritstone areas. Calcium status was assessed from serum calcium concentration, femur weight, ash content of the body, calcium concentration in the femur and body ash. There was no significant difference in serum calcium concentration, femur calcium concentration and body ash calcium concentration between animals from the limestone and the gritstone. However, on the limestone, bank voles, but not wood mice, had significantly heavier femora and a greater proportion of ash in the body compared with their gritstone counterparts.

Calcium binding to an elastic portion of connectin/titin filaments.

Science.gov (United States)

Tatsumi, R; Maeda, K; Hattori, A; Takahashi, K

2001-01-01

Da fragment was changed by the binding of calcium ions, connectin filaments could be expected to alter their elasticity during the contraction-relaxation cycle of skeletal muscle.

Simulations of the global carbon cycle and anthropogenic CO{sub 2} transient. Annual report

Energy Technology Data Exchange (ETDEWEB)

Sarmiento, J.L.

1994-07-01

This research focuses on improving the understanding of the anthropogenic carbon dioxide transient using observations and models of the past and present. In addition, an attempt is made to develop an ability to predict the future of the carbon cycle in response to continued anthropogenic perturbations and climate change. Three aspects of the anthropogenic carbon budget were investigated: (1) the globally integrated budget at the present time; (2) the time history of the carbon budget; and (3) the spatial distribution of carbon fluxes. One of the major activities of this study was the participation in the model comparison study of Enting, et al. [1994] carried out in preparation for the IPCC 1994 report.

Why Calcium? How Calcium Became the Best Communicator.

Science.gov (United States)

Carafoli, Ernesto; Krebs, Joachim

2016-09-30

Calcium carries messages to virtually all important functions of cells. Although it was already active in unicellular organisms, its role became universally important after the transition to multicellular life. In this Minireview, we explore how calcium ended up in this privileged position. Most likely its unique coordination chemistry was a decisive factor as it makes its binding by complex molecules particularly easy even in the presence of large excesses of other cations, e.g. magnesium. Its free concentration within cells can thus be maintained at the very low levels demanded by the signaling function. A large cadre of proteins has evolved to bind or transport calcium. They all contribute to buffer it within cells, but a number of them also decode its message for the benefit of the target. The most important of these "calcium sensors" are the EF-hand proteins. Calcium is an ambivalent messenger. Although essential to the correct functioning of cell processes, if not carefully controlled spatially and temporally within cells, it generates variously severe cell dysfunctions, and even cell death. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

PeakCaller: an automated graphical interface for the quantification of intracellular calcium obtained by high-content screening.

Science.gov (United States)

Artimovich, Elena; Jackson, Russell K; Kilander, Michaela B C; Lin, Yu-Chih; Nestor, Michael W

2017-10-16

Intracellular calcium is an important ion involved in the regulation and modulation of many neuronal functions. From regulating cell cycle and proliferation to initiating signaling cascades and regulating presynaptic neurotransmitter release, the concentration and timing of calcium activity governs the function and fate of neurons. Changes in calcium transients can be used in high-throughput screening applications as a basic measure of neuronal maturity, especially in developing or immature neuronal cultures derived from stem cells. Using human induced pluripotent stem cell derived neurons and dissociated mouse cortical neurons combined with the calcium indicator Fluo-4, we demonstrate that PeakCaller reduces type I and type II error in automated peak calling when compared to the oft-used PeakFinder algorithm under both basal and pharmacologically induced conditions. Here we describe PeakCaller, a novel MATLAB script and graphical user interface for the quantification of intracellular calcium transients in neuronal cultures. PeakCaller allows the user to set peak parameters and smoothing algorithms to best fit their data set. This new analysis script will allow for automation of calcium measurements and is a powerful software tool for researchers interested in high-throughput measurements of intracellular calcium.

An overview of techniques for the measurement of calcium distribution, calcium fluxes, and cytosolic free calcium in mammalian cells

International Nuclear Information System (INIS)

Borle, A.B.

1990-01-01

An array of techniques can be used to study cell calcium metabolism that comprises several calcium compartments and many types of transport systems such as ion channels, ATP-dependent pumps, and antiporters. The measurement of total call calcium brings little information of value since 60 to 80% of total cell calcium is actually bound to the extracellular glycocalyx. Cell fractionation and differential centrifugation have been used to study intracellular Ca 2+ compartmentalization, but the methods suffer from the possibility of Ca 2+ loss or redistribution among cell fractions. Steady-state kinetic analyses of 45 Ca uptake or desaturation curves have been used to study the distribution of Ca 2+ among various kinetic pools in living cells and their rate of Ca 2+ exchange, but the analyses are constrained by many limitations. Nonsteady-state tracer studies can provide information about rapid changes in calcium influx or efflux in and out of the cell. Zero-time kinetics of 45 Ca uptake can detect instantaneous changes in calcium influx, while 45 Ca fractional efflux ratio, can detect rapid stimulations or inhibitions of calcium efflux out of cells. The best strategy to study cell calcium metabolism is to use several different methods that focus on a specific problem from widely different angles

When Product Life Cycle Meets Customer Activity Cycle

DEFF Research Database (Denmark)

Tan, Adrian Ronald

2007-01-01

Manufacturing companies have traditionally focused their efforts on designing, developing and producing products to offer on the market. Today global competition and demands for greater company responsibility of products throughout their entire life cycle are driving manufacturing companies to sh...

Calcium and Mitosis

Science.gov (United States)

Hepler, P.

1983-01-01

Although the mechanism of calcium regulation is not understood, there is evidence that calcium plays a role in mitosis. Experiments conducted show that: (1) the spindle apparatus contains a highly developed membrane system that has many characteristics of sarcoplasmic reticulum of muscle; (2) this membrane system contains calcium; and (3) there are ionic fluxes occurring during mitosis which can be seen by a variety of fluorescence probes. Whether the process of mitosis can be modulated by experimentally modulating calcium is discussed.

N2O emissions from the global agricultural nitrogen cycle – current state and future scenarios

Directory of Open Access Journals (Sweden)

H. Lotze-Campen

2012-10-01

Full Text Available Reactive nitrogen (Nr is not only an important nutrient for plant growth, thereby safeguarding human alimentation, but it also heavily disturbs natural systems. To mitigate air, land, aquatic, and atmospheric pollution caused by the excessive availability of Nr, it is crucial to understand the long-term development of the global agricultural Nr cycle. For our analysis, we combine a material flow model with a land-use optimization model. In a first step we estimate the state of the Nr cycle in 1995. In a second step we create four scenarios for the 21st century in line with the SRES storylines. Our results indicate that in 1995 only half of the Nr applied to croplands was incorporated into plant biomass. Moreover, less than 10 per cent of all Nr in cropland plant biomass and grazed pasture was consumed by humans. In our scenarios a strong surge of the Nr cycle occurs in the first half of the 21st century, even in the environmentally oriented scenarios. Nitrous oxide (N2O emissions rise from 3 Tg N2O-N in 1995 to 7–9 in 2045 and 5–12 Tg in 2095. Reinforced Nr pollution mitigation efforts are therefore required.

Calcium ion binding properties of Medicago truncatula calcium/calmodulin-dependent protein kinase.

Science.gov (United States)

Swainsbury, David J K; Zhou, Liang; Oldroyd, Giles E D; Bornemann, Stephen

2012-09-04

A calcium/calmodulin-dependent protein kinase (CCaMK) is essential in the interpretation of calcium oscillations in plant root cells for the establishment of symbiotic relationships with rhizobia and mycorrhizal fungi. Some of its properties have been studied in detail, but its calcium ion binding properties and subsequent conformational change have not. A biophysical approach was taken with constructs comprising either the visinin-like domain of Medicago truncatula CCaMK, which contains EF-hand motifs, or this domain together with the autoinhibitory domain. The visinin-like domain binds three calcium ions, leading to a conformational change involving the exposure of hydrophobic surfaces and a change in tertiary but not net secondary or quaternary structure. The affinity for calcium ions of visinin-like domain EF-hands 1 and 2 (K(d) = 200 ± 50 nM) was appropriate for the interpretation of calcium oscillations (~125-850 nM), while that of EF-hand 3 (K(d) ≤ 20 nM) implied occupancy at basal calcium ion levels. Calcium dissociation rate constants were determined for the visinin-like domain of CCaMK, M. truncatula calmodulin 1, and the complex between these two proteins (the slowest of which was 0.123 ± 0.002 s(-1)), suggesting the corresponding calcium association rate constants were at or near the diffusion-limited rate. In addition, the dissociation of calmodulin from the protein complex was shown to be on the same time scale as the dissociation of calcium ions. These observations suggest that the formation and dissociation of the complex between calmodulin and CCaMK would substantially mirror calcium oscillations, which typically have a 90 s periodicity.

Osteopetrorickets due to Snx10 deficiency in mice results from both failed osteoclast activity and loss of gastric acid-dependent calcium absorption.

Directory of Open Access Journals (Sweden)

Liang Ye

2015-03-01

Full Text Available Mutations in sorting nexin 10 (Snx10 have recently been found to account for roughly 4% of all human malignant osteopetrosis, some of them fatal. To study the disease pathogenesis, we investigated the expression of Snx10 and created mouse models in which Snx10 was knocked down globally or knocked out in osteoclasts. Endocytosis is severely defective in Snx10-deficient osteoclasts, as is extracellular acidification, ruffled border formation, and bone resorption. We also discovered that Snx10 is highly expressed in stomach epithelium, with mutations leading to high stomach pH and low calcium solubilization. Global Snx10-deficiency in mice results in a combined phenotype: osteopetrosis (due to osteoclast defect and rickets (due to high stomach pH and low calcium availability, resulting in impaired bone mineralization. Osteopetrorickets, the paradoxical association of insufficient mineralization in the context of a positive total body calcium balance, is thought to occur due to the inability of the osteoclasts to maintain normal calcium-phosphorus homeostasis. However, osteoclast-specific Snx10 knockout had no effect on calcium balance, and therefore led to severe osteopetrosis without rickets. Moreover, supplementation with calcium gluconate rescued mice from the rachitic phenotype and dramatically extended life span in global Snx10-deficient mice, suggesting that this may be a life-saving component of the clinical approach to Snx10-dependent human osteopetrosis that has previously gone unrecognized. We conclude that tissue-specific effects of Snx10 mutation need to be considered in clinical approaches to this disease entity. Reliance solely on hematopoietic stem cell transplantation can leave hypocalcemia uncorrected with sometimes fatal consequences. These studies established an essential role for Snx10 in bone homeostasis and underscore the importance of gastric acidification in calcium uptake.

Water Cycle Missions for the Next Decade

Science.gov (United States)

Houser, P. R.

2013-12-01

The global water cycle describes the circulation of water as a vital and dynamic substance in its liquid, solid, and vapor phases as it moves through the atmosphere, oceans and land. Life in its many forms exists because of water, and modern civilization depends on learning how to live within the constraints imposed by the availability of water. The scientific challenge posed by the need to observe the global water cycle is to integrate in situ and space-borne observations to quantify the key water-cycle state variables and fluxes. The vision to address that challenge is a series of Earth observation missions that will measure the states, stocks, flows, and residence times of water on regional to global scales followed by a series of coordinated missions that will address the processes, on a global scale, that underlie variability and changes in water in all its three phases. The accompanying societal challenge is to foster the improved use of water data and information as a basis for enlightened management of water resources, to protect life and property from effects of extremes in the water cycle. A major change in thinking about water science that goes beyond its physics to include its role in ecosystems and society is also required. Better water-cycle observations, especially on the continental and global scales, will be essential. Water-cycle predictions need to be readily available globally to reduce loss of life and property caused by water-related natural hazards. Building on the 2007 Earth Science Decadal Survey, NASA's Plan for a Climate-Centric Architecture for Earth Observations and Applications from Space , and the 2012 Chapman Conference on Remote Sensing of the Terrestrial Water Cycle, a workshop was held in April 2013 to gather wisdom and determine how to prepare for the next generation of water cycle missions in support of the second Earth Science Decadal Survey. This talk will present the outcomes of the workshop including the intersection between

Calcium Carbonate

Science.gov (United States)

... Calcium is needed by the body for healthy bones, muscles, nervous system, and heart. Calcium carbonate also ... to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in ...

Calcium en cardioplegie

NARCIS (Netherlands)

Ruigrok, T.J.C.; Meijler, F.L.

1985-01-01

Coronary perfusion with a calcium-free solution, followed by reperfusion with a calcium containing solution, may result in acute myocardial cell death and in irreversible loss of the e1ectrical and mechanical activity of the heart. This phenomenon is known as the calcium paradox. A number of

Development of new historical global Nitrogen fertilizer map and the evaluation of their impacts on terrestrial N cycling and the evaluation of their impacts on terrestrial N cycling

Science.gov (United States)

Nishina, K.; Ito, A.; Hayashi, S.

2015-12-01

The use of synthetic nitrogen fertilizer was rapidly growing up after the birth of Haber-Bosch process in the early 20th century. The recent N loading derived from these sources on terrestrial ecosystems was estimated 2 times higher than biogenic N fixation in terrestrial ecosystems (Gruber et al., 2009). However, there are still large uncertainties in cumulative N impacts on terrestrial impact at global scale. In this study, to assess historical N impacts at global scale, we made a new global N fertilizer input map, which was a spatial-temporal explicit map (during 1960-2010) and considered the fraction of NH4+ and NO3- in the N fertilizer inputs. With the developed N fertilizer map, we evaluated historical N20 cycling changes by land-use changes and N depositions in N cycling using ecosystem model 'VISIT'. Prior to the downscaling processes for global N fertilizer map, we applied the statistical data imputation to FAOSTAT data due to there existing many missing data especially in developing countries. For the data imputation, we used multiple data imputation method proposed by Honaker & King (2010). The statistics of various types of synthetic fertilizer consumption are available in FAOSTAT, which can be sorted by the content of NH4+ and NO3-, respectively. To downscaling the country by country N fertilizer consumptions data to the 0.5˚x 0.5˚ grid-based map, we used historical land-use map in Earthstat (Rumankutty et al., 1999). Before the assignment of N fertilizer in each grid, we weighted the double cropping regions to be more N fertilizer input on to these regions. Using M3-Crops Data (Monfreda et al., 2008), we picked up the dominant cropping species in each grid cell. After that, we used Crop Calendar in SAGE dataset (Sacks et al., 2010) and determined schedule of N fertilizer input in each grid cell using dominant crop calendar. Base fertilizer was set to be 7 days before transplanting and second fertilizer to be 30 days after base fertilizer application

Filamin and phospholipase C-ε are required for calcium signaling in the Caenorhabditis elegans spermatheca.

Directory of Open Access Journals (Sweden)

Ismar Kovacevic

2013-05-01

Full Text Available The Caenorhabditis elegans spermatheca is a myoepithelial tube that stores sperm and undergoes cycles of stretching and constriction as oocytes enter, are fertilized, and exit into the uterus. FLN-1/filamin, a stretch-sensitive structural and signaling scaffold, and PLC-1/phospholipase C-ε, an enzyme that generates the second messenger IP3, are required for embryos to exit normally after fertilization. Using GCaMP, a genetically encoded calcium indicator, we show that entry of an oocyte into the spermatheca initiates a distinctive series of IP3-dependent calcium oscillations that propagate across the tissue via gap junctions and lead to constriction of the spermatheca. PLC-1 is required for the calcium release mechanism triggered by oocyte entry, and FLN-1 is required for timely initiation of the calcium oscillations. INX-12, a gap junction subunit, coordinates propagation of the calcium transients across the spermatheca. Gain-of-function mutations in ITR-1/IP3R, an IP3-dependent calcium channel, and loss-of-function mutations in LFE-2, a negative regulator of IP3 signaling, increase calcium release and suppress the exit defect in filamin-deficient animals. We further demonstrate that a regulatory cassette consisting of MEL-11/myosin phosphatase and NMY-1/non-muscle myosin is required for coordinated contraction of the spermatheca. In summary, this study answers long-standing questions concerning calcium signaling dynamics in the C. elegans spermatheca and suggests FLN-1 is needed in response to oocyte entry to trigger calcium release and coordinated contraction of the spermathecal tissue.

Calcium Electroporation

DEFF Research Database (Denmark)

Frandsen, Stine Krog; Gibot, Laure; Madi, Moinecha

2015-01-01

BACKGROUND: Calcium electroporation describes the use of high voltage electric pulses to introduce supraphysiological calcium concentrations into cells. This promising method is currently in clinical trial as an anti-cancer treatment. One very important issue is the relation between tumor cell kill...... efficacy-and normal cell sensitivity. METHODS: Using a 3D spheroid cell culture model we have tested the effect of calcium electroporation and electrochemotherapy using bleomycin on three different human cancer cell lines: a colorectal adenocarcinoma (HT29), a bladder transitional cell carcinoma (SW780......), and a breast adenocarcinoma (MDA-MB231), as well as on primary normal human dermal fibroblasts (HDF-n). RESULTS: The results showed a clear reduction in spheroid size in all three cancer cell spheroids three days after treatment with respectively calcium electroporation (p

Insight into the Global Carbon Cycle from Assimilation of Satellite CO2 measurements

Science.gov (United States)

Baker, D. F.

2017-12-01

A key goal of satellite CO2 measurements is to provide sufficient spatio-temporal coverage to constrain portions of the globe poorly observed by the in situ network, especially the tropical land regions. While systematic errors in both measurements and modeling remain a challenge, these satellite data are providing new insight into the functioning of the global carbon cycle, most notably across the recent 2015-16 En Niño. Here we interpret CO2 measurements from the GOSAT and OCO-2 satellites, as well as from the global in situ network (both surface sites and routine aircraft profiles), using a 4DVar-based global CO2 flux inversion across 2009-2017. The GOSAT data indicate that the tropical land regions are responsible for most of the observed global variability in CO2 across the last 8+ years. For the most recent couple of years where they overlap, the OCO-2 data give the same result, an +2 PgC/yr shift towards CO2 release in the ENSO warm phase, while disagreeing somewhat on the absolute value of the flux. The variability given by both these satellites disagrees with that given by an in situ-only inversion across the recent 2015-16 El Niño: the +2 PgC/yr shift from the satellites is double that given by the in situ data alone, suggesting that the more complete coverage is providing a more accurate view. For the current release of OCO-2 data (version 7), however, the flux results given by the OCO-2 land data (from both nadir- and glint-viewing modes) disagree significantly with those given by the ocean glint data; we examine the soon-to-be-released v8 data to assess whether these systematic retrieval errors have been reduced, and whether the corrected OCO-2 ocean data support the result from the land data. We discuss finer-scale features flux results given by the satellite data, and examine the importance of the flux prior, as well.

Coordination cycles

Czech Academy of Sciences Publication Activity Database

Steiner, Jakub

2008-01-01

Roč. 63, č. 1 (2008), s. 308-327 ISSN 0899-8256 Institutional research plan: CEZ:AV0Z70850503 Keywords : global games * coordination * crises * cycles and fluctuations Subject RIV: AH - Economics Impact factor: 1.333, year: 2008

Effect of calcium intake on urinary oxalate excretion in calcium stone-forming patients

Directory of Open Access Journals (Sweden)

Nishiura J.L.

2002-01-01

Full Text Available Dietary calcium lowers the risk of nephrolithiasis due to a decreased absorption of dietary oxalate that is bound by intestinal calcium. The aim of the present study was to evaluate oxaluria in normocalciuric and hypercalciuric lithiasic patients under different calcium intake. Fifty patients (26 females and 24 males, 41 ± 10 years old, whose 4-day dietary records revealed a regular low calcium intake (<=500 mg/day, received an oral calcium load (1 g/day for 7 days. A 24-h urine was obtained before and after load and according to the calciuria under both diets, patients were considered as normocalciuric (NC, N = 15, diet-dependent hypercalciuric (DDHC, N = 9 or diet-independent hypercalciuric (DIHC, N = 26. On regular diet, mean oxaluria was 30 ± 14 mg/24 h for all patients. The 7-day calcium load induced a significant decrease in mean oxaluria compared to the regular diet in NC and DIHC (20 ± 12 vs 26 ± 7 and 27 ± 18 vs 32 ± 15 mg/24 h, respectively, P<0.05 but not in DDHC patients (22 ± 10 vs 23 ± 5 mg/24 h. The lack of an oxalate decrease among DDHC patients after the calcium load might have been due to higher calcium absorption under higher calcium supply, with a consequent lower amount of calcium left in the intestine to bind with oxalate. These data suggest that a long-lasting regular calcium consumption <500 mg was not associated with high oxaluria and that a subpopulation of hypercalciuric patients who presented a higher intestinal calcium absorption (DDHC tended to hyperabsorb oxalate as well, so that oxaluria did not change under different calcium intake.

Determination of phosphorus and calcium in biological samples by activation with 14 MeV neutrons

International Nuclear Information System (INIS)

Berretta, Jose Roberto

1995-01-01

Analytical methods for phosphorus and calcium in biological samples by means of activation with 14 MeV neutrons, using the Van de Graaff accelerator from the Instituto de Pesquisas Energeticas e Nucleares, SP, Brazil are developed. For phosphorus analysis, powder samples were pressed into pellets, weighed and transferred to polyethylene plastic envelopes. The pellets with cadmium shielding were irradiated under a fast neutron flux for 5 to 10 minutes, and further counted in a HPGe detector for 5 minutes. Calcium analysis was performed by cyclic irradiation. Samples were irradiated for 10 minutes. After a decay time of 2 minutes, gamma counting was performed for 10 minutes. After a decay time of 2 minutes, a new irradiation ws made. The irradiation cycle was repeated 5 times and the counting spectrum obtained in each cycle was accumulated in the multi channel analyser. The variation of the neutron flux was followed by using a BF 3 detector calibrated with and aluminium monitor. By means of the gamma spectrum and the neutron counting of the BF 3 detector it was possible to estimate phosphorus and calcium concentrations in the sample analyzed. The methods were checked in the reference samples from the International Atomic Energy Agency and in commercial samples of powder milk, fertilizer and animal bone. Phosphorus contents in bone (A3/74) and milk (A-11) reference materials were (15.6 +- 1.8%) and (0.9 +- 0.1)%, respectively. These values are in good agreement to the certified values (15.5 +- 0.5)% and (0.910 +- 0.102)%, respectively. Calcium analysis carried out in bone (A3/74) presented a value of (31.8+-4.1)% and the certified value was of (31.3 +- 0.3)%. Detection limits for phosphorus and calcium were determined in different analyzed samples. The agreement of the results obtained with the certified values confirmed the suitability of the methods for phosphorus and calcium analysis. The methods are fast and laborious chemical procedures are not required. (author)

Understanding the Global Water and Energy Cycle Through Assimilation of Precipitation-Related Observations: Lessons from TRMM and Prospects for GPM

Science.gov (United States)

Hou, Arthur; Zhang, Sara; daSilva, Arlindo; Li, Frank; Atlas, Robert (Technical Monitor)

2002-01-01

Understanding the Earth's climate and how it responds to climate perturbations relies on what we know about how atmospheric moisture, clouds, latent heating, and the large-scale circulation vary with changing climatic conditions. The physical process that links these key climate elements is precipitation. Improving the fidelity of precipitation-related fields in global analyses is essential for gaining a better understanding of the global water and energy cycle. In recent years, research and operational use of precipitation observations derived from microwave sensors such as the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager and Special Sensor Microwave/Imager (SSM/I) have shown the tremendous potential of using these data to improve global modeling, data assimilation, and numerical weather prediction. We will give an overview of the benefits of assimilating TRMM and SSM/I rain rates and discuss developmental strategies for using space-based rainfall and rainfall-related observations to improve forecast models and climate datasets in preparation for the proposed multi-national Global Precipitation Mission (GPM).

Nuclear Fuel Cycle Information System. A directory of nuclear fuel cycle facilities. 2009 ed

International Nuclear Information System (INIS)

2009-04-01

The Nuclear Fuel Cycle Information System (NFCIS) is an international directory of civilian nuclear fuel cycle facilities, published online as part of the Integrated Nuclear Fuel Cycle Information System (iNFCIS: http://www-nfcis.iaea.org/). This is the fourth hardcopy publication in almost 30 years and it represents a snapshot of the NFCIS database as of the end of 2008. Together with the attached CD-ROM, it provides information on 650 civilian nuclear fuel cycle facilities in 53 countries, thus helping to improve the transparency of global nuclear fuel cycle activities

Calcium - ionized

Science.gov (United States)

... diuretics Thrombocytosis (high platelet count) Tumors Vitamin A excess Vitamin D excess Lower-than-normal levels may be due to: Hypoparathyroidism Malabsorption Osteomalacia Pancreatitis Renal failure Rickets Vitamin D deficiency Alternative Names Free calcium; Ionized calcium ...

Calcium absorption and achlorhydria

International Nuclear Information System (INIS)

Recker, R.R.

1985-01-01

Defective absorption of calcium has been thought to exist in patients with achlorhydria. The author compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium used as the carrier. Mean calcium absorption (+/- S.D.) in the patients with achlorhydria was 0.452 +/- 0.125 for citrate and 0.042 +/- 0.021 for carbonate (P less than 0.0001). Fractional calcium absorption in the normal subjects was 0.243 +/- 0.049 for citrate and 0.225 +/- 0.108 for carbonate (not significant). Absorption of calcium from carbonate in patients with achlorhydria was significantly lower than in the normal subjects and was lower than absorption from citrate in either group; absorption from citrate in those with achlorhydria was significantly higher than in the normal subjects, as well as higher than absorption from carbonate in either group. Administration of calcium carbonate as part of a normal breakfast resulted in completely normal absorption in the achlorhydric subjects. These results indicate that calcium absorption from carbonate is impaired in achlorhydria under fasting conditions. Since achlorhydria is common in older persons, calcium carbonate may not be the ideal dietary supplement

Study of calcium chloride and calcium nitrate purification on inorganic sorbents

International Nuclear Information System (INIS)

Vasil'eva, L.V.; Knyazeva, A.N.; Fakeev, A.A.; Belyaeva, N.A.; Morozov, V.I.; Kucherova, V.V.

1986-01-01

Purification of calcium chloride and calcium nitrate from iron, chromium, manganese and cobalt impurities by sorption on some inorganic collectors are considered in this article. Study was conducted by means of radioactive-tracer technique at concurrent use of several γ-radioactive isotopes. As a collectors were used hydrated aluminium and zirconium oxides. Dependence of effectiveness of precipitation by collectors on ph-value of medium, quantity of collector, nature and concentration of components is studied. Optimal parameters of purification of calcium chloride and calcium nitrate are defined.

Molecular models of alginic acid: Interactions with calcium ions and calcite surfaces

Science.gov (United States)

Perry, Thomas D.; Cygan, Randall T.; Mitchell, Ralph

2006-07-01

Cation binding by polysaccharides is observed in many environments and is important for predictive environmental modeling, and numerous industrial and food technology applications. The complexities of these cation-organic interactions are well suited for predictive molecular modeling and the analysis of conformation and configuration of polysaccharides and their influence on cation binding. In this study, alginic acid was chosen as a model polymer system and representative disaccharide and polysaccharide subunits were developed. Molecular dynamics simulation of the torsion angles of the ether linkage between various monomeric subunits identified local and global energy minima for selected disaccharides. The simulations indicate stable disaccharide configurations and a common global energy minimum for all disaccharide models at Φ = 274 ± 7°, Ψ = 227 ± 5°, where Φ and Ψ are the torsion angles about the ether linkage. The ability of disaccharide subunits to bind calcium ions and to associate with the (101¯4) surface of calcite was also investigated. Molecular models of disaccharide interactions with calcite provide binding energy differences for conformations that are related to the proximity and residence densities of the electron-donating moieties with calcium ions on the calcite surface, which are controlled, in part, by the torsion of the ether linkage between monosaccharide units. Dynamically optimized configurations for polymer alginate models with calcium ions were also derived.

Stochastic simulations of calcium contents in sugarcane area

Directory of Open Access Journals (Sweden)

Gener T. Pereira

2015-08-01

Full Text Available ABSTRACTThe aim of this study was to quantify and to map the spatial distribution and uncertainty of soil calcium (Ca content in a sugarcane area by sequential Gaussian and simulated-annealing simulation methods. The study was conducted in the municipality of Guariba, northeast of the São Paulo state. A sampling grid with 206 points separated by a distance of 50 m was established, totaling approximately 42 ha. The calcium contents were evaluated in layer of 0-0.20 m. Techniques of geostatistical estimation, ordinary kriging and stochastic simulations were used. The technique of ordinary kriging does not reproduce satisfactorily the global statistics of the Ca contents. The use of simulation techniques allows reproducing the spatial variability pattern of Ca contents. The techniques of sequential Gaussian simulation and simulated annealing showed significant variations in the contents of Ca in the small scale.

Dynamical analysis of the global business-cycle synchronization.

Science.gov (United States)

Lopes, António M; Tenreiro Machado, J A; Huffstot, John S; Mata, Maria Eugénia

2018-01-01

This paper reports the dynamical analysis of the business cycles of 12 (developed and developing) countries over the last 56 years by applying computational techniques used for tackling complex systems. They reveal long-term convergence and country-level interconnections because of close contagion effects caused by bilateral networking exposure. Interconnectivity determines the magnitude of cross-border impacts. Local features and shock propagation complexity also may be true engines for local configuration of cycles. The algorithmic modeling proves to represent a solid approach to study the complex dynamics involved in the world economies.

Dynamical analysis of the global business-cycle synchronization

Science.gov (United States)

2018-01-01

This paper reports the dynamical analysis of the business cycles of 12 (developed and developing) countries over the last 56 years by applying computational techniques used for tackling complex systems. They reveal long-term convergence and country-level interconnections because of close contagion effects caused by bilateral networking exposure. Interconnectivity determines the magnitude of cross-border impacts. Local features and shock propagation complexity also may be true engines for local configuration of cycles. The algorithmic modeling proves to represent a solid approach to study the complex dynamics involved in the world economies. PMID:29408909

The carbon cycle and global warming

International Nuclear Information System (INIS)

Anon.

1991-01-01

Five land-use-based approaches can be used to slow the buildup of CO 2 in the atmosphere: slowing or stopping the loss of existing forests, thus preserving current carbon reservoirs; adding to the planet's vegetative cover through reforestation or other means, thus enlarging living terrestrial carbon reservoirs; increasing the carbon stored in nonliving carbon reservoirs such as agricultural soils; increasing the carbon stored in artificial reservoirs, including timber products; and substituting sustainable biomass energy sources for fossil fuel consumption, thus reducing energy-related carbon emissions. These approaches are all based on the same basic premise: adding to the planet's net carbon stores in vegetative cover or soil, or preventing any net loss, will help moderate global warming by keeping atmospheric CO 2 levels lower than they would otherwise be. Because biotic policy options appear capable of contributing significantly to the mitigation of global warming while also furthering many other public policy objectives, their role deserves careful consideration on a country-by-country basis

Calcium sensing in exocytosis

DEFF Research Database (Denmark)

Gustavsson, Natalia; Wu, Bingbing; Han, Weiping

2012-01-01

an increase in intracellular calcium levels. Besides the triggering role, calcium signaling modulates the precise amount and kinetics of vesicle release. Thus, it is a central question to understand the molecular machineries responsible for calcium sensing in exocytosis. Here we provide an overview of our...... current understanding of calcium sensing in neurotransmitter release and hormone secretion....

Evaluation of salivary electrolytes during estrous cycle in Murrah buffaloes with reference to estrus detection

Directory of Open Access Journals (Sweden)

Indu Devi

2016-10-01

Full Text Available Aim: Timely estrus detection is one of the critical factors for increasing reproductive efficiency in buffaloes. In recent decades, saliva has become a more popular as a noninvasive source for determining physiological status of animals by various biochemical electrolytes. This study was designed to assess and correlate changes in different salivary minerals concentration (calcium, inorganic phosphorus, magnesium, sodium, potassium, and chloride during different stages of the estrous cycle in Murrah buffaloes. Materials and Methods: The saliva samples were collected during the different phases of the estrous cycle from 20 Murrah buffaloes in early morning hours and were assayed using respective minerals assay kits. Results: The concentrations of calcium (8.76±0.08-12.11±0.11 mg/dl, inorganic phosphorus (6.56±0.13-14.72±4.50 mg/dl, magnesium (2.27±0.14-5.79±0.15 mg/dl, sodium (139.47±0.31-159.62±1.22 mmol/L, potassium (12.40±0.22-26.85±1.22 mmol/L, and chloride (109.28±0.41-137.07±0.68 mmol/L varied during the different phases of estrous cycle. The concentration of calcium, inorganic phosphorus, magnesium, sodium, potassium, and chloride in saliva were significantly (p<0.01 higher during estrus phase compared to other phases of the estrous cycle. All these minerals were positively and significantly (p<0.0001 related to estrogen concentration while salivary concentrations of calcium, magnesium, sodium, and chloride showed a significant (p<0.0001 negative correlation with progesterone level in blood plasma. Conclusion: These preliminary findings indicate that there are definite variations in salivary mineral and electrolyte concentrations during different phases of the estrous cycle. These results may be used as an aid for estrus detection/ confirmation in buffaloes although validation of the results using a large number of animals is required.

CALCIUM-RICH GAP TRANSIENTS: SOLVING THE CALCIUM CONUNDRUM IN THE INTRACLUSTER MEDIUM

International Nuclear Information System (INIS)

Mulchaey, John S.; Kollmeier, Juna A.; Kasliwal, Mansi M.

2014-01-01

X-ray measurements suggest that the abundance of calcium in the intracluster medium is higher than can be explained using favored models for core-collapse and Type Ia supernovae alone. We investigate whether the ''calcium conundrum'' in the intracluster medium can be alleviated by including a contribution from the recently discovered subclass of supernovae known as calcium-rich gap transients. Although the calcium-rich gap transients make up only a small fraction of all supernovae events, we find that their high calcium yields are sufficient to reproduce the X-ray measurements found for nearby rich clusters. We find the χ 2 goodness-of-fit metric improves from 84 to 2 by including this new class. Moreover, calcium-rich supernovae preferentially occur in the outskirts of galaxies making it easier for the nucleosynthesis products of these events to be incorporated in the intracluster medium via ram-pressure stripping. The discovery of calcium-rich gap transients in clusters and groups far from any individual galaxy suggests that supernovae associated with intracluster stars may play an important role in enriching the intracluster medium. Calcium-rich gap transients may also help explain anomalous calcium abundances in many other astrophysical systems including individual stars in the Milky Way, the halos of nearby galaxies, and the circumgalactic medium. Our work highlights the importance of considering the diversity of supernovae types and corresponding yields when modeling the abundance of the intracluster medium and other gas reservoirs

Estimation of ionized calcium, total calcium and albumin corrected calcium for the diagnosis of hypocalcaemia of malignancy

International Nuclear Information System (INIS)

Ijaz, A.; Mehmood, T.; Qureshi, A.H.; Anwar, M.; Dilawar, M.; Hussain, I.; Khan, F.A.; Khan, D.A.; Hussain, S.; Khan, I.A.

2006-01-01

Objective: To measure levels of ionized calcium, total calcium and albumin corrected calcium in patients with different malignant disorders for the diagnosis of hypercalcaemia of malignancy. Design: A case control comparative study. Place and Duration of Study: The study was carried out in the Department of Pathology, Army Medical College Rawalpindi, Armed Forces Institute of Pathology and Department of Oncology CMH, Rawalpindi from March 2003 to December 2003. Subjects and Methods: Ninety-seven patients of various malignant disorders, admitted in the Department of Oncology, CMH, Rawalpindi, and 39 age and gender-matched disease-free persons (as control) were included in the study. Blood ionized calcium (Ca/sup ++/), pH, sodium (Na/sup +/) and potassium (K/sup +/) were analysed by Ion selective electrode (ISE) on Easylyte> auto analyser. Other related parameters were measured by colorimetric methods. Results: Blood Ca/sup ++/ levels in patients suffering from malignant disorders were found significantly high (mean +- j 1.30+017 mmoV/L) as compared to control subjects (mean +- 1.23+0.03 mmoV/L) (p<0.001). The number of patients with hypercalcaemia of malignancy detected by Ca/sup ++/ estimation was significantly higher (38%) as compared to total calcium (8.4%) and albumin corrected calcium ACC (10.6%) (p<0.001). There was no statistically significant difference in other parameters e.g. phosphate, urea, creatinine, pH, Na/sup +/ and K/sup +/ levels in study subjects and controls. Conclusion: Detection of hypercalcaemia can be markedly improved if ionized calcium estimation is used in patients with malignant disorders. (author)

SR calcium handling and calcium after-transients in a rabbit model of heart failure

NARCIS (Netherlands)

Baartscheer, Antonius; Schumacher, Cees A.; Belterman, Charly N. W.; Coronel, Ruben; Fiolet, Jan W. T.

2003-01-01

Objective: After-depolarization associated arrhythmias are frequently observed in heart failure and associated with spontaneous calcium release from sarcoplasmic reticulum (SR), calcium after-transients. We hypothesize that disturbed SR calcium handling underlies calcium after-transients in heart

Calcium absorption from fortified ice cream formulations compared with calcium absorption from milk.

Science.gov (United States)

van der Hee, Regine M; Miret, Silvia; Slettenaar, Marieke; Duchateau, Guus S M J E; Rietveld, Anton G; Wilkinson, Joy E; Quail, Patricia J; Berry, Mark J; Dainty, Jack R; Teucher, Birgit; Fairweather-Tait, Susan J

2009-05-01

Optimal bone mass in early adulthood is achieved through appropriate diet and lifestyle, thereby protecting against osteoporosis and risk of bone fracture in later life. Calcium and vitamin D are essential to build adequate bones, but calcium intakes of many population groups do not meet dietary reference values. In addition, changes in dietary patterns are exacerbating the problem, thereby emphasizing the important role of calcium-rich food products. We have designed a calcium-fortified ice cream formulation that is lower in fat than regular ice cream and could provide a useful source of additional dietary calcium. Calcium absorption from two different ice cream formulations was determined in young adults and compared with milk. Sixteen healthy volunteers (25 to 45 years of age), recruited from the general public of The Netherlands, participated in a randomized, reference-controlled, double-blind cross-over study in which two test products and milk were consumed with a light standard breakfast on three separate occasions: a standard portion of ice cream (60 g) fortified with milk minerals and containing a low level (3%) of butter fat, ice cream (60 g) fortified with milk minerals and containing a typical level (9%) of coconut oil, and reduced-fat milk (1.7% milk fat) (200 mL). Calcium absorption was measured by the dual-label stable isotope technique. Effects on calcium absorption were evaluated by analysis of variance. Fractional absorption of calcium from the 3% butterfat ice cream, 9% coconut oil ice cream, and milk was 26%+/-8%, 28%+/-5%, and 31%+/-9%, respectively, and did not differ significantly (P=0.159). Results indicate that calcium bioavailability in the two calcium-fortified ice cream formulations used in this study is as high as milk, indicating that ice cream may be a good vehicle for delivery of calcium.

Uptake of radiactive calcium by groundnut (Arachis hypogaea L. ) and efficiency of utilisation of applied calcium

Energy Technology Data Exchange (ETDEWEB)

Loganathan, S; Krishnamoorthy, K K [Tamil Nadu Agricultural Univ., Coimbatore (India). Dept. of Soil Science and Agricultural Chemistry

1977-04-01

A pot experiment was conducted with groundnut applying labelled calcium as its sulphate and carbonate at two levels namely 75 and 150 kg Ca per ha with varying levels of P, K and Mg. Plant samples were taken at different stages of crop growth and analysed for the content of radioactive calcium. Calcium sulphate treatment has resulted in larger uptake of calcium compared to calcium carbonate. An application of 150 kg Ca per ha has caused significantly higher uptake by groundnut plant than 75 kg Ca per ha. The percentage of utilisation of added calcium ranged from 2.2 to 5.4 Recovery of calcium by plants was more in calcium sulphate treatment rather than in calcium carbonate. The plants showed a preference for absorbing applied calcium rather than native calcium.

Uptake of radiactive calcium by groundnut (Arachis hypogaea L.) and efficiency of utilisation of applied calcium

International Nuclear Information System (INIS)

Loganathan, S.; Krishnamoorthy, K.K.

1977-01-01

A pot experiment was conducted with groundnut applying labelled calcium as its sulphate and carbonate at two levels namely 75 and 150 kg Ca per ha with varying levels of P, K and Mg. Plant samples were taken at different stages of crop growth and analysed for the content of radioactive calcium. Calcium sulphate treatment has resulted in larger uptake of calcium compared to calcium carbonate. An application of 150 kg Ca per ha has caused significantly higher uptake by groundnut plant than 75 kg Ca per ha. The percentage of utilisation of added calcium ranged from 2.2 to 5.4 Recovery of calcium by plants was more in calcium sulphate treatment rather than in calcium carbonate. The plants showed a preference for absorbing applied calcium rather than native calcium

Chemistry of organic carbon in soil with relationship to the global carbon cycle

International Nuclear Information System (INIS)

Post, W.M. III.

1988-01-01

Various ecosystem disturbances alter the balances between production of organic matter and its decomposition and therefore change the amount of carbon in soil. The most severe perturbation is conversion of natural vegetation to cultivated crops. Conversion of natural vegetation to cultivated crops results in a lowered input of slowly decomposing material which causes a reduction in overall carbon levels. Disruption of soil matrix structure by cultivation leads to lowered physical protection of organic matter resulting in an increased net mineralization rate of soil carbon. Climate change is another perturbation that affects the amount and composition of plant production, litter inputs, and decomposition regimes but does not affect soil structure directly. Nevertheless, large changes in soil carbon storage are probable with anticipated CO 2 induced climate change, particularly in northern latitudes where anticipated climate change will be greatest (MacCracken and Luther 1985) and large amounts of soil organic matter are found. It is impossible, given the current state of knowledge of soil organic matter processes and transformations to develop detailed process models of soil carbon dynamics. Largely phenomenological models appear to be developing into predictive tools for understanding the role of soil organic matter in the global carbon cycle. In particular, these models will be useful in quantifying soil carbon changes due to human land-use and to anticipated global climate and vegetation changes. 47 refs., 7 figs., 2 tabs

Calcium in plant cells

Directory of Open Access Journals (Sweden)

V. V. Schwartau

2014-04-01

Full Text Available The paper gives the review on the role of calcium in many physiological processes of plant organisms, including growth and development, protection from pathogenic influences, response to changing environmental factors, and many other aspects of plant physiology. Initial intake of calcium ions is carried out by Ca2+-channels of plasma membrane and they are further transported by the xylem owing to auxins’ attractive ability. The level of intake and selectivity of calcium transport to ove-ground parts of the plant is controlled by a symplast. Ca2+enters to the cytoplasm of endoderm cells through calcium channels on the cortical side of Kaspary bands, and is redistributed inside the stele by the symplast, with the use of Ca2+-АТPases and Ca2+/Н+-antiports. Owing to regulated expression and activity of these calcium transporters, calclum can be selectively delivered to the xylem. Important role in supporting calcium homeostasis is given to the vacuole which is the largest depo of calcium. Regulated quantity of calcium movement through the tonoplast is provided by a number of potential-, ligand-gated active transporters and channels, like Ca2+-ATPase and Ca2+/H+ exchanger. They are actively involved in the inactivation of the calcium signal by pumping Ca2+ to the depo of cells. Calcium ATPases are high affinity pumps that efficiently transfer calcium ions against the concentration gradient in their presence in the solution in nanomolar concentrations. Calcium exchangers are low affinity, high capacity Ca2+ transporters that are effectively transporting calcium after raising its concentration in the cell cytosol through the use of protons gradients. Maintaining constant concentration and participation in the response to stimuli of different types also involves EPR, plastids, mitochondria, and cell wall. Calcium binding proteins contain several conserved sequences that provide sensitivity to changes in the concentration of Ca2+ and when you

An Exploration of the Calcium-Binding Mode of Egg White Peptide, Asp-His-Thr-Lys-Glu, and In Vitro Calcium Absorption Studies of Peptide-Calcium Complex.

Science.gov (United States)

Sun, Na; Jin, Ziqi; Li, Dongmei; Yin, Hongjie; Lin, Songyi

2017-11-08

The binding mode between the pentapeptide (DHTKE) from egg white hydrolysates and calcium ions was elucidated upon its structural and thermodynamics characteristics. The present study demonstrated that the DHTKE peptide could spontaneously bind calcium with a 1:1 stoichiometry, and that the calcium-binding site corresponded to the carboxyl oxygen, amino nitrogen, and imidazole nitrogen atoms of the DHTKE peptide. Moreover, the effect of the DHTKE-calcium complex on improving the calcium absorption was investigated in vitro using Caco-2 cells. Results showed that the DHTKE-calcium complex could facilitate the calcium influx into the cytosol and further improve calcium absorption across Caco-2 cell monolayers by more than 7 times when compared to calcium-free control. This study facilitates the understanding about the binding mechanism between peptides and calcium ions as well as suggests a potential application of egg white peptides as nutraceuticals to improve calcium absorption.

Oral calcium carbonate affects calcium but not phosphorus balance in stage 3–4 chronic kidney disease

Science.gov (United States)

Hill, Kathleen M.; Martin, Berdine R.; Wastney, Meryl; McCabe, George P.; Moe, Sharon M.; Weaver, Connie M.; Peacock, Munro

2014-01-01

Chronic kidney disease (CKD) patients are given calcium carbonate to bind dietary phosphorus and reduce phosphorus retention, and to prevent negative calcium balance. Data are limited on calcium and phosphorus balance in CKD to support this. The aim of this study was to determine calcium and phosphorus balance and calcium kinetics with and without calcium carbonate in CKD patients. Eight stage 3/4 CKD patients, eGFR 36 mL/min, participated in two 3-week balances in a randomized placebo-controlled cross-over study of calcium carbonate (1500 mg/d calcium). Calcium and phosphorus balance were determined on a controlled diet. Oral and intravenous 45calcium with blood sampling and urine and fecal collections were used for calcium kinetics. Fasting blood and urine were collected at baseline and end of each week of each balance period for biochemical analyses. Results showed that patients were in neutral calcium and phosphorus balance while on placebo. Calcium carbonate produced positive calcium balance, did not affect phosphorus balance, and produced only a modest reduction in urine phosphorus excretion compared with placebo. Calcium kinetics demonstrated positive net bone balance but less than overall calcium balance suggesting tissue deposition. Fasting biochemistries of calcium and phosphate homeostasis were unaffected by calcium carbonate. If they can be extrapolated to effects of chronic therapy, these data caution against the use of calcium carbonate as a phosphate binder. PMID:23254903

A comparison of advanced heat recovery power cycles in a combined cycle for large ships

DEFF Research Database (Denmark)

Larsen, Ulrik; Sigthorsson, Oskar; Haglind, Fredrik

2014-01-01

Strong motivation exists within the marine sector to reduce fuel expenses and to comply with ever stricter emission regulations. Heat recovery can address both of these issues. The ORC (organic Rankine cycle), the Kalina cycle and the steam Rankine cycle have received the majority of the focus...... fluids possess high global warming potentials and hazard levels. It is concluded that the ORC has the greatest potential for increasing the fuel efficiency, and the combined cycle offers very high thermal efficiency. While being less efficient, the steam cycle has the advantages of being well proven...

Calcium inhibition of the NAD+-linked isocitrate dehydrogenase from blowfly flight muscle mitochondria.

Science.gov (United States)

Bulos, B A; Thomas, B J; Sacktor, B

1984-08-25

Free Ca2+ was shown to inhibit the NAD+-isocitrate dehydrogenase from blowfly flight muscle mitochondria. Inhibition by free Ca2+ concentrations of 40 microM or greater was found in the absence or presence of ADP and citrate, two known activators of the enzyme. Calcium decreased the affinity of the enzyme for its substrate, the magnesium DL-isocitrate chelate; no change in the apparent V of the reaction was observed. Calcium was inhibitory when activity was measured in the presence of fixed concentrations of magnesium DL-isocitrate chelate in the presence of several fixed concentrations of either free isocitrate3-, an activator, or free Mg2+, an inhibitor of the enzyme. That NAD+-isocitrate dehydrogenase from blowfly flight muscle mitochondria was not activated by micromolar free Ca2+ is consistent with the view that calcium does not play a role in regulating the flux through the tricarboxylate cycle in this species.

Calcium carbonate scaling kinetics determined from radiotracer experiments with calcium-47

International Nuclear Information System (INIS)

Turner, C.W.; Smith, D.W.

1998-01-01

The deposition rate of calcium carbonate on a heat-transfer surface has been measured using a calcium-47 radiotracer and compared to the measured rate of thermal fouling. The crystalline phase of calcium carbonate that precipitates depends on the degree of supersaturation at the heat-transfer surface, with aragonite precipitating at higher supersaturations and calcite precipitating at lower supersaturations. Whereas the mass deposition rates were constant with time, the thermal fouling rates decreased throughout the course of each experiment as a result of densification of the deposit. It is proposed that the densification was driven by the temperature gradient across the deposit together with the retrograde solubility of calcium carbonate. The temperature dependence of the deposition rate yielded an activation energy of 79 ± 4 kJ/mol for the precipitation of calcium carbonate on a heat-transfer surface. (author)

Calcium Signaling in Taste Cells

Science.gov (United States)

Medler, Kathryn F.

2014-01-01

The sense of taste is a common ability shared by all organisms and is used to detect nutrients as well as potentially harmful compounds. Thus taste is critical to survival. Despite its importance, surprisingly little is known about the mechanisms generating and regulating responses to taste stimuli. All taste responses depend on calcium signals to generate appropriate responses which are relayed to the brain. Some taste cells have conventional synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release to formulate an output signal through a hemichannel. Beyond establishing these characteristics, few studies have focused on understanding how these calcium signals are formed. We identified multiple calcium clearance mechanisms that regulate calcium levels in taste cells as well as a calcium influx that contributes to maintaining appropriate calcium homeostasis in these cells. Multiple factors regulate the evoked taste signals with varying roles in different cell populations. Clearly, calcium signaling is a dynamic process in taste cells and is more complex than has previously been appreciated. PMID:25450977

Analysis of the Global Warming Potential of Biogenic CO2 Emission in Life Cycle Assessments.

Science.gov (United States)

Liu, Weiguo; Zhang, Zhonghui; Xie, Xinfeng; Yu, Zhen; von Gadow, Klaus; Xu, Junming; Zhao, Shanshan; Yang, Yuchun

2017-01-03

Biomass is generally believed to be carbon neutral. However, recent studies have challenged the carbon neutrality hypothesis by introducing metric indicators to assess the global warming potential of biogenic CO 2 (GWP bio ). In this study we calculated the GWP bio factors using a forest growth model and radiative forcing effects with a time horizon of 100 years and applied the factors to five life cycle assessment (LCA) case studies of bioproducts. The forest carbon change was also accounted for in the LCA studies. GWP bio factors ranged from 0.13-0.32, indicating that biomass could be an attractive energy resource when compared with fossil fuels. As expected, short rotation and fast-growing biomass plantations produced low GWP bio . Long-lived wood products also allowed more regrowth of biomass to be accounted as absorption of the CO 2 emission from biomass combustion. The LCA case studies showed that the total life cycle GHG emissions were closely related to GWP bio and energy conversion efficiency. By considering the GWP bio factors and the forest carbon change, the production of ethanol and bio-power appeared to have higher GHG emissions than petroleum-derived diesel at the highest GWP bio .

Analysis of the Global Warming Potential of Biogenic CO2 Emission in Life Cycle Assessments

Science.gov (United States)

Liu, Weiguo; Zhang, Zhonghui; Xie, Xinfeng; Yu, Zhen; von Gadow, Klaus; Xu, Junming; Zhao, Shanshan; Yang, Yuchun

2017-01-01

Biomass is generally believed to be carbon neutral. However, recent studies have challenged the carbon neutrality hypothesis by introducing metric indicators to assess the global warming potential of biogenic CO2 (GWPbio). In this study we calculated the GWPbio factors using a forest growth model and radiative forcing effects with a time horizon of 100 years and applied the factors to five life cycle assessment (LCA) case studies of bioproducts. The forest carbon change was also accounted for in the LCA studies. GWPbio factors ranged from 0.13–0.32, indicating that biomass could be an attractive energy resource when compared with fossil fuels. As expected, short rotation and fast-growing biomass plantations produced low GWPbio. Long-lived wood products also allowed more regrowth of biomass to be accounted as absorption of the CO2 emission from biomass combustion. The LCA case studies showed that the total life cycle GHG emissions were closely related to GWPbio and energy conversion efficiency. By considering the GWPbio factors and the forest carbon change, the production of ethanol and bio-power appeared to have higher GHG emissions than petroleum-derived diesel at the highest GWPbio. PMID:28045111

Calcium Pyrophosphate Deposition (CPPD)

Science.gov (United States)

... Patient / Caregiver Diseases & Conditions Calcium Pyrophosphate Deposition (CPPD) Calcium Pyrophosphate Deposition (CPPD) Fast Facts The risk of ... young people, too. Proper diagnosis depends on detecting calcium pyrophosphate crystals in the fluid of an affected ...

Calcium and bones (image)

Science.gov (United States)

Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...

Antenatal calcium intake in Malaysia.

Science.gov (United States)

Mahdy, Zaleha Abdullah; Basri, Hashimah; Md Isa, Zaleha; Ahmad, Shuhaila; Shamsuddin, Khadijah; Mohd Amin, Rahmah

2014-04-01

To determine the adequacy of antenatal calcium intake in Malaysia, and the influencing factors. A cross-sectional study was conducted among postnatal women who delivered in two tertiary hospitals. Data were collected from antenatal cards, hospital documents and diet recall on daily milk and calcium intake during pregnancy. SPSS version 19.0 was used for statistical analyses. A total of 150 women were studied. The total daily calcium intake was 834 ± 43 mg (mean ± standard error of the mean), but the calcium intake distribution curve was skewed to the right with a median intake of 725 mg daily. When calcium intake from milk and calcium supplements was excluded, the daily dietary calcium intake was only 478 ± 25 mg. Even with inclusion of milk and calcium supplements, more than a third (n=55 or 36.7%) of the women consumed less than 600 mg calcium in their daily diet. The adequacy of daily calcium intake was not influenced by maternal age, ethnicity, income or maternal job or educational status as well as parity. The daily dietary calcium intake of the Malaysian antenatal population is far from adequate without the addition of calcium supplements and milk. © 2013 The Authors. Journal of Obstetrics and Gynaecology Research © 2013 Japan Society of Obstetrics and Gynecology.

Calcium channel blocker poisoning

Directory of Open Access Journals (Sweden)

Miran Brvar

2005-04-01

Full Text Available Background: Calcium channel blockers act at L-type calcium channels in cardiac and vascular smooth muscles by preventing calcium influx into cells with resultant decrease in vascular tone and cardiac inotropy, chronotropy and dromotropy. Poisoning with calcium channel blockers results in reduced cardiac output, bradycardia, atrioventricular block, hypotension and shock. The findings of hypotension and bradycardia should suggest poisoning with calcium channel blockers.Conclusions: Treatment includes immediate gastric lavage and whole-bowel irrigation in case of ingestion of sustainedrelease products. All patients should receive an activated charcoal orally. Specific treatment includes calcium, glucagone and insulin, which proved especially useful in shocked patients. Supportive care including the use of catecholamines is not always effective. In the setting of failure of pharmacological therapy transvenous pacing, balloon pump and cardiopulmonary by-pass may be necessary.

The Hepatitis B Virus X Protein Elevates Cytosolic Calcium Signals by Modulating Mitochondrial Calcium Uptake

Science.gov (United States)

Yang, Bei

2012-01-01

Chronic hepatitis B virus (HBV) infections are associated with the development of hepatocellular carcinoma (HCC). The HBV X protein (HBx) is thought to play an important role in the development of HBV-associated HCC. One fundamental HBx function is elevation of cytosolic calcium signals; this HBx activity has been linked to HBx stimulation of cell proliferation and transcription pathways, as well as HBV replication. Exactly how HBx elevates cytosolic calcium signals is not clear. The studies described here show that HBx stimulates calcium entry into cells, resulting in an increased plateau level of inositol 1,4,5-triphosphate (IP3)-linked calcium signals. This increased calcium plateau can be inhibited by blocking mitochondrial calcium uptake and store-operated calcium entry (SOCE). Blocking SOCE also reduced HBV replication. Finally, these studies also demonstrate that there is increased mitochondrial calcium uptake in HBx-expressing cells. Cumulatively, these studies suggest that HBx can increase mitochondrial calcium uptake and promote increased SOCE to sustain higher cytosolic calcium and stimulate HBV replication. PMID:22031934

Effect of anions or foods on absolute bioavailability of calcium from calcium salts in mice by pharmacokinetics

OpenAIRE

Zenei Taira, Zenei; Ueda,Yukari

2013-01-01

Yukari Ueda, Zenei TairaFaculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, JapanAbstract: We studied the absolute bioavailability of calcium from calcium L-lactate in mice using pharmacokinetics, and reviewed the absolute bioavailability of calcium from three other calcium salts in mice previously studied: calcium chloride, calcium acetate, and calcium ascorbate. The results showed that calcium metabolism is linear between intravenous administration of 15 mg/kg and 30 ...

A strategy of precipitated calcium carbonate (CaCO3) fillers for enhancing the mechanical properties of polypropylene polymers

International Nuclear Information System (INIS)

Thenepalli, Thriveni; Ahn, Ji Whan; Ahn, Young Jun; Han, Choon; Ramakrishna, Chilakala

2015-01-01

A wide variety of fillers are currently used in more than twenty types of polymer resins, although four of them alone (polypropylene, polyamides, thermoplastic polyesters, and polyvinyl chloride) account for 90% of the market of mineral fillers in plastics. Polypropylene (PP) and PVC dominate the market for calcium carbonate. PP is a versatile reinforcement material that can meet engineering and structural specifications and is widely used for automotive components, home appliances, and industrial applications. Talc, mica, clay, kaolin, wollastonite, calcium carbonates, feldspar, aluminum hydroxide, glass fibers, and natural fibers are commonly used in fillers. Among these, calcium carbonate (both natural and synthetic) is the mos abundant and affords the possibility of improved surface finishing, control over the manufacture of products, and increased electric resistance and impact resistance. Meeting the global challenge to reduce the weight of vehicles by using plastics is a significant issue. The current the global plastic and automobile industry cannot survive without fillers, additives, and reinforcements. Polypropylene is a major component of the modern plastic industry, and currently is used in dashboards, wheel covers, and some engine parts in automobiles. This article reports that the use of calcium carbonate fillers with polypropylene is the best choice to enhance the mechanical properties of plastic parts used in automobiles

Consistency of seven different GNSS global ionospheric mapping techniques during one solar cycle

Science.gov (United States)

Roma-Dollase, David; Hernández-Pajares, Manuel; Krankowski, Andrzej; Kotulak, Kacper; Ghoddousi-Fard, Reza; Yuan, Yunbin; Li, Zishen; Zhang, Hongping; Shi, Chuang; Wang, Cheng; Feltens, Joachim; Vergados, Panagiotis; Komjathy, Attila; Schaer, Stefan; García-Rigo, Alberto; Gómez-Cama, José M.

2018-06-01

In the context of the International GNSS Service (IGS), several IGS Ionosphere Associated Analysis Centers have developed different techniques to provide global ionospheric maps (GIMs) of vertical total electron content (VTEC) since 1998. In this paper we present a comparison of the performances of all the GIMs created in the frame of IGS. Indeed we compare the classical ones (for the ionospheric analysis centers CODE, ESA/ESOC, JPL and UPC) with the new ones (NRCAN, CAS, WHU). To assess the quality of them in fair and completely independent ways, two assessment methods are used: a direct comparison to altimeter data (VTEC-altimeter) and to the difference of slant total electron content (STEC) observed in independent ground reference stations (dSTEC-GPS). The main conclusion of this study, performed during one solar cycle, is the consistency of the results between so many different GIM techniques and implementations.

Voltage-Gated Calcium Channels

Science.gov (United States)

Zamponi, Gerald Werner

Voltage Gated Calcium Channels is the first comprehensive book in the calcium channel field, encompassing over thirty years of progress towards our understanding of calcium channel structure, function, regulation, physiology, pharmacology, and genetics. This book balances contributions from many of the leading authorities in the calcium channel field with fresh perspectives from risings stars in the area, taking into account the most recent literature and concepts. This is the only all-encompassing calcium channel book currently available, and is an essential resource for academic researchers at all levels in the areas neuroscience, biophysics, and cardiovascular sciences, as well as to researchers in the drug discovery area.

Application of molecular calcium compounds in catalysis and hydrogen storage; Anwendung von molekularen Calcium-Verbindungen in der Katalyse und der Wasserstoffspeicherung

Energy Technology Data Exchange (ETDEWEB)

Spielmann, Jan

2010-07-20

1. Applications in catalysis: In the course of this work new catalytic applications of calcium compounds and in particular hydrocarbon-soluble calcium hydride species have been investigated. The complex [(DIPP-nacnac)CaH(THF)]2 (1, DIPP-nacnac = HC[C(Me)N-2,6-(i-Pr)-C6H3]2) served as a model system to test reactivity of the calcium hydride in stoichiometric reactions on a molecular level. It has been found that the hydroboration of conjugated alkenes with catecholborane can be accelerated considerably by using catalytic amounts of calcium complexes. However it was shown that calcium hydride species catalyze the decomposition of catecholborane to BH3 which is probably the catalytically active species. Investigations on the catalytic hydrosilylation of ketones have demonstrated that calcium complexes are efficient catalysts for this reaction. In the proposed catalytic cycle of this reaction six-coordinate hypervalent silicon species play a crucial role. Furthermore it has been shown that molecular calcium compounds are catalysts for the hydrogenation of conjugated alkenes with H2 under relatively mild conditions (20 bar H2, 20 C). Both steps in the proposed catalytical cycle i.e. addition of a metal hydride to the C=C double bond and a heterolytic cleavage of H2 by a calcium alkyl compound have been confirmed experimentally. 2. Applications in hydrogen storage: Ligand stabilized metal amidoborane complexes in the form of (DIPP-nacnac)MNH(R)BH3(THF)x (M = Ca, Mg; R = H, Me, i-Pr, 2,6-(i-Pr)-C6H3; x = 0, 1, 2) have been synthesized and structurally characterized. These complexes are model systems for the metal amidoborane compounds M(NH2BH3)n (M = Li, Na, n = 1; M = Ca, n = 2), which are potential high capacity hydrogen storage materials. To get insights in their dehydrogenation mechanisms the thermal decomposition of the model compounds was investigated in solution. This allowed for the first isolation of well-defined dehydrogenated products which have been

The Contemporary Carbon Cycle

Science.gov (United States)

Houghton, R. A.

2003-12-01

The global carbon cycle refers to the exchanges of carbon within and between four major reservoirs: the atmosphere, the oceans, land, and fossil fuels. Carbon may be transferred from one reservoir to another in seconds (e.g., the fixation of atmospheric CO2 into sugar through photosynthesis) or over millennia (e.g., the accumulation of fossil carbon (coal, oil, gas) through deposition and diagenesis of organic matter). This chapter emphasizes the exchanges that are important over years to decades and includes those occurring over the scale of months to a few centuries. The focus will be on the years 1980-2000 but our considerations will broadly include the years ˜1850-2100. Chapter 8.09, deals with longer-term processes that involve rates of carbon exchange that are small on an annual timescale (weathering, vulcanism, sedimentation, and diagenesis).The carbon cycle is important for at least three reasons. First, carbon forms the structure of all life on the planet, making up ˜50% of the dry weight of living things. Second, the cycling of carbon approximates the flows of energy around the Earth, the metabolism of natural, human, and industrial systems. Plants transform radiant energy into chemical energy in the form of sugars, starches, and other forms of organic matter; this energy, whether in living organisms or dead organic matter, supports food chains in natural ecosystems as well as human ecosystems, not the least of which are industrial societies habituated (addicted?) to fossil forms of energy for heating, transportation, and generation of electricity. The increased use of fossil fuels has led to a third reason for interest in the carbon cycle. Carbon, in the form of carbon dioxide (CO2) and methane (CH4), forms two of the most important greenhouse gases. These gases contribute to a natural greenhouse effect that has kept the planet warm enough to evolve and support life (without the greenhouse effect the Earth's average temperature would be -33�

The Arctic Ocean marine carbon cycle: evaluation of air-sea CO2 exchanges, ocean acidification impacts and potential feedbacks

Directory of Open Access Journals (Sweden)

N. R. Bates

2009-11-01

Full Text Available At present, although seasonal sea-ice cover mitigates atmosphere-ocean gas exchange, the Arctic Ocean takes up carbon dioxide (CO2 on the order of −66 to −199 Tg C year−1 (1012 g C, contributing 5–14% to the global balance of CO2 sinks and sources. Because of this, the Arctic Ocean has an important influence on the global carbon cycle, with the marine carbon cycle and atmosphere-ocean CO2 exchanges sensitive to Arctic Ocean and global climate change feedbacks. In the near-term, further sea-ice loss and increases in phytoplankton growth rates are expected to increase the uptake of CO2 by Arctic Ocean surface waters, although mitigated somewhat by surface warming in the Arctic. Thus, the capacity of the Arctic Ocean to uptake CO2 is expected to alter in response to environmental changes driven largely by climate. These changes are likely to continue to modify the physics, biogeochemistry, and ecology of the Arctic Ocean in ways that are not yet fully understood. In surface waters, sea-ice melt, river runoff, cooling and uptake of CO2 through air-sea gas exchange combine to decrease the calcium carbonate (CaCO3 mineral saturation states (Ω of seawater while seasonal phytoplankton primary production (PP mitigates this effect. Biological amplification of ocean acidification effects in subsurface waters, due to the remineralization of organic matter, is likely to reduce the ability of many species to produce CaCO3 shells or tests with profound implications for Arctic marine ecosystems

Different sorbents in calcium looping cycle for CO{sub 2} capture

Energy Technology Data Exchange (ETDEWEB)

Luo, Cong; Zheng, Ying; Ding, Ning [Huazhong Univ. of Science and Technology, Wuhan (China). State Key Lab. of Coal Combustion

2013-07-01

Cyclic CO{sub 2} capture using commercial pure micro CaCO{sub 3} and nano CaCO{sub 3} is investigated in this paper which focuses on the different characteristics two different sorbents during high temperature reactions. The results indicate that the nano CaCO{sub 3} sorbent has higher carbonation conversions and carbonation rates than the micro CaCO{sub 3} sorbent in the cyclic reactions. Furthermore, nano sorbent can retain its fast carbonation rates at the beginning dozens of seconds during each cycle. In contrast, the carbonation rates of micro sorbent diminish with the increase of cycle number. But, unfortunately, CaO derived from nano CaCO3 sorbent sinter much easily. Its grains, which are composed of numerous spherical nanocrystallites, experience dramatic morphological changes during high temperature reactions.

Highly stable aqueous zinc-ion storage using a layered calcium vanadium oxide bronze cathode

Energy Technology Data Exchange (ETDEWEB)

Xia, Chuan; Guo, Jing; Li, Peng; Zhang, Xixiang; Alshareef, Husam N. [Materials Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal (Saudi Arabia)

2018-04-03

Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn{sup 2+} intercalation chemistry, stand out as they can employ high-capacity Zn metal as the anode material. Herein, we report a layered calcium vanadium oxide bronze as the cathode material for aqueous Zn batteries. For the storage of the Zn{sup 2+} ions in the aqueous electrolyte, we demonstrate that the calcium-based bronze structure can deliver a high capacity of 340 mA h g{sup -1} at 0.2 C, good rate capability, and very long cycling life (96 % retention after 3000 cycles at 80 C). Further, we investigate the Zn{sup 2+} storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 W h kg{sup -1} at a power density of 53.4 W kg{sup -1}. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

The influence of calcium-45 on the inhibitive effect of calcium hexameta-phosphate combination and the electrocapillary effect of calcium-45

International Nuclear Information System (INIS)

Subramanyan, N.; Venkatakrishna Iyer, S.; Kapali, V.

1978-01-01

Corrosion of steel in an aqueous chloride solution is significantly accelerated if calcium (NaHMP)-45 is substituted for ordinary calcium when calcium and sodium metaphosphate combination was investigated for inhibiting action. In this investigation it is seen that the anodic polarisation of steel is brought down when 45 Ca is present in the different solutions containing Ca, non radioactive calcium and (NaHMP) at pH 5.5, 7.5 and 9.0 except in one case when 45 Ca is present alone in the solution of pH 5.5. The uptake of 45 Ca is more at the positive potentials than at the negative. Electrocapillary measurements with calcium chloride solution show that the electrocapillary curve is lifted above that for the base solution particularly on the positive side of the electrocapillary maximum. These interesting observations are explained by the postulate that radioactive calcium behaves like an anion and the acceleration of corrosion is attributed essentially to radiolytically produced hydrogen peroxide. (author)

Calcium binding by dietary fibre

International Nuclear Information System (INIS)

James, W.P.T.; Branch, W.J.; Southgate, D.A.T.

1978-01-01

Dietary fibre from plants low in phytate bound calcium in proportion to its uronic-acid content. This binding by the non-cellulosic fraction of fibre reduces the availability of calcium for small-intestinal absorption, but the colonic microbial digestion of uronic acids liberates the calcium. Thus the ability to maintain calcium balance on high-fibre diets may depend on the adaptive capacity on the colon for calcium. (author)

Evaluating the N-cycle module of LPJ-GUESS at the site-scale

NARCIS (Netherlands)

Fleischer, Katrin; Warlind, David; van der Molen, Michiel; Rebel, Karin; Willem Erisman, Jan; Arneth, Almut; Wassen, Martin; Smith, Ben; Dolman, Han

Global scale dynamic vegetation models simulate the global C cycle and atmosphere-vegetation interactions, an essential component in the global climate system. The important role of the N-cycle in determining fluxes of carbon and climate dynamics is unequivocally evident. The current generation of

The NEWS Water Cycle Climatology

Science.gov (United States)

Rodell, M.; Beaudoing, H. K.; L'Ecuyer, T.; Olson, W. S.

2012-12-01

NASA's Energy and Water Cycle Study (NEWS) program fosters collaborative research towards improved quantification and prediction of water and energy cycle consequences of climate change. In order to measure change, it is first necessary to describe current conditions. The goal of the first phase of the NEWS Water and Energy Cycle Climatology project was to develop "state of the global water cycle" and "state of the global energy cycle" assessments based on data from modern ground and space based observing systems and data integrating models. The project was a multi-institutional collaboration with more than 20 active contributors. This presentation will describe the results of the water cycle component of the first phase of the project, which include seasonal (monthly) climatologies of water fluxes over land, ocean, and atmosphere at continental and ocean basin scales. The requirement of closure of the water budget (i.e., mass conservation) at various scales was exploited to constrain the flux estimates via an optimization approach that will also be described. Further, error assessments were included with the input datasets, and we examine these in relation to inferred uncertainty in the optimized flux estimates in order to gauge our current ability to close the water budget within an expected uncertainty range.

The NEWS Water Cycle Climatology

Science.gov (United States)

Rodell, Matthew; Beaudoing, Hiroko Kato; L'Ecuyer, Tristan; William, Olson

2012-01-01

NASA's Energy and Water Cycle Study (NEWS) program fosters collaborative research towards improved quantification and prediction of water and energy cycle consequences of climate change. In order to measure change, it is first necessary to describe current conditions. The goal of the first phase of the NEWS Water and Energy Cycle Climatology project was to develop "state of the global water cycle" and "state of the global energy cycle" assessments based on data from modern ground and space based observing systems and data integrating models. The project was a multi-institutional collaboration with more than 20 active contributors. This presentation will describe the results of the water cycle component of the first phase of the project, which include seasonal (monthly) climatologies of water fluxes over land, ocean, and atmosphere at continental and ocean basin scales. The requirement of closure of the water budget (i.e., mass conservation) at various scales was exploited to constrain the flux estimates via an optimization approach that will also be described. Further, error assessments were included with the input datasets, and we examine these in relation to inferred uncertainty in the optimized flux estimates in order to gauge our current ability to close the water budget within an expected uncertainty range.

Dengue and Calcium

OpenAIRE

Shivanthan, Mitrakrishnan C; Rajapakse, Senaka

2014-01-01

Dengue is potentially fatal unless managed appropriately. No specific treatment is available and the mainstay of treatment is fluid management with careful monitoring, organ support, and correction of metabolic derangement. Evidence with regards to the role of calcium homeostasis in dengue is limited. Low blood calcium levels have been demonstrated in dengue infection and hypocalcemia maybe more pronounced in more severe forms. The cause of hypocalcemia is likely to be multifactorial. Calcium...

Synthesis of calcium hydroxyapatite from calcium carbonate and different orthophosphate sources: A comparative study

International Nuclear Information System (INIS)

Pham Minh, Doan; Lyczko, Nathalie; Sebei, Haroun; Nzihou, Ange; Sharrock, Patrick

2012-01-01

Highlights: ► Calcium hydroxyapatite was synthesized from CaCO 3 and four orthophosphates. ► Only H 3 PO 4 led to the complete precipitation of orthophosphate species. ► H 3 PO 4 was also the most efficient for calcium dissolution. ► Reaction pathway was dissolution-precipitation accompanied by agglomeration step. - Abstract: The synthesis of calcium hydroxyapatite (Ca-HA) starting from calcium carbonate and different orthophosphate sources, including orthophosphoric acid, potassium, sodium and ammonium dihydrogen orthophosphates, was investigated under ambient conditions. The reaction started with calcium carbonate dissolution in an acid medium, followed by rapid precipitation of calcium cations with orthophosphate species to form calcium phosphate based particles which were in the size range of 0.4–1 μm. These particles then agglomerated into much larger ones, up to 350 μm in diameter (aggregates). These aggregates possessed an unstable porous structure which was responsible for the porosity of the final products. The highest specific surface area and pore volume were obtained with potassium dihydrogen orthophosphate. On the other hand, orthophosphoric acid led to the highest dissolution of calcium carbonate and the complete precipitation of orthophosphate species. Under ambient conditions, calcium phosphate based solid products of low crystallinity were formed. Different intermediates were identified and a reaction pathway proposed.

Testosterone increases urinary calcium excretion and inhibits expression of renal calcium transport proteins.

NARCIS (Netherlands)

Hsu, Y.J.; Dimke, H.; Schoeber, J.P.H.; Hsu, S.C.; Lin, S.H.; Chu, P.; Hoenderop, J.G.J.; Bindels, R.J.M.

2010-01-01

Although gender differences in the renal handling of calcium have been reported, the overall contribution of androgens to these differences remains uncertain. We determined here whether testosterone affects active renal calcium reabsorption by regulating calcium transport proteins. Male mice had

Calcium metabolism in birds.

Science.gov (United States)

de Matos, Ricardo

2008-01-01

Calcium is one of the most important plasma constituents in mammals and birds. It provides structural strength and support (bones and eggshell) and plays vital roles in many of the biochemical reactions in the body. The control of calcium metabolism in birds is highly efficient and closely regulated in a number of tissues, primarily parathyroid gland, intestine, kidney, and bone. The hormones with the greatest involvement in calcium regulation in birds are parathyroid hormone, 1,25-dihydroxyvitamin D(3) (calcitriol), and estrogen, with calcitonin playing a minor and uncertain role. The special characteristics of calcium metabolism in birds, mainly associated with egg production, are discussed, along with common clinical disorders secondary to derangements in calcium homeostasis.

Implementation of methane cycling for deep-time global warming simulations with the DCESS Earth system model (version 1.2)

Science.gov (United States)

Shaffer, Gary; Fernández Villanueva, Esteban; Rondanelli, Roberto; Olaf Pepke Pedersen, Jens; Malskær Olsen, Steffen; Huber, Matthew

2017-11-01

Geological records reveal a number of ancient, large and rapid negative excursions of the carbon-13 isotope. Such excursions can only be explained by massive injections of depleted carbon to the Earth system over a short duration. These injections may have forced strong global warming events, sometimes accompanied by mass extinctions such as the Triassic-Jurassic and end-Permian extinctions 201 and 252 million years ago, respectively. In many cases, evidence points to methane as the dominant form of injected carbon, whether as thermogenic methane formed by magma intrusions through overlying carbon-rich sediment or from warming-induced dissociation of methane hydrate, a solid compound of methane and water found in ocean sediments. As a consequence of the ubiquity and importance of methane in major Earth events, Earth system models for addressing such events should include a comprehensive treatment of methane cycling but such a treatment has often been lacking. Here we implement methane cycling in the Danish Center for Earth System Science (DCESS) model, a simplified but well-tested Earth system model of intermediate complexity. We use a generic methane input function that allows variation in input type, size, timescale and ocean-atmosphere partition. To be able to treat such massive inputs more correctly, we extend the model to deal with ocean suboxic/anoxic conditions and with radiative forcing and methane lifetimes appropriate for high atmospheric methane concentrations. With this new model version, we carried out an extensive set of simulations for methane inputs of various sizes, timescales and ocean-atmosphere partitions to probe model behavior. We find that larger methane inputs over shorter timescales with more methane dissolving in the ocean lead to ever-increasing ocean anoxia with consequences for ocean life and global carbon cycling. Greater methane input directly to the atmosphere leads to more warming and, for example, greater carbon dioxide release

Implementation of methane cycling for deep-time global warming simulations with the DCESS Earth system model (version 1.2

Directory of Open Access Journals (Sweden)

G. Shaffer

2017-11-01

Full Text Available Geological records reveal a number of ancient, large and rapid negative excursions of the carbon-13 isotope. Such excursions can only be explained by massive injections of depleted carbon to the Earth system over a short duration. These injections may have forced strong global warming events, sometimes accompanied by mass extinctions such as the Triassic-Jurassic and end-Permian extinctions 201 and 252 million years ago, respectively. In many cases, evidence points to methane as the dominant form of injected carbon, whether as thermogenic methane formed by magma intrusions through overlying carbon-rich sediment or from warming-induced dissociation of methane hydrate, a solid compound of methane and water found in ocean sediments. As a consequence of the ubiquity and importance of methane in major Earth events, Earth system models for addressing such events should include a comprehensive treatment of methane cycling but such a treatment has often been lacking. Here we implement methane cycling in the Danish Center for Earth System Science (DCESS model, a simplified but well-tested Earth system model of intermediate complexity. We use a generic methane input function that allows variation in input type, size, timescale and ocean–atmosphere partition. To be able to treat such massive inputs more correctly, we extend the model to deal with ocean suboxic/anoxic conditions and with radiative forcing and methane lifetimes appropriate for high atmospheric methane concentrations. With this new model version, we carried out an extensive set of simulations for methane inputs of various sizes, timescales and ocean–atmosphere partitions to probe model behavior. We find that larger methane inputs over shorter timescales with more methane dissolving in the ocean lead to ever-increasing ocean anoxia with consequences for ocean life and global carbon cycling. Greater methane input directly to the atmosphere leads to more warming and, for example

Calcium Isotope Fractionation during Carbonate Weathering in the Northern Guangdong, South China

Science.gov (United States)

Liu, F.; Mao, G.; Wei, G.; Zhang, Z.

2017-12-01

global Ca and C cycles.

Calcium Balance in Chronic Kidney Disease.

Science.gov (United States)

Hill Gallant, Kathleen M; Spiegel, David M

2017-06-01

The kidneys play a critical role in the balance between the internal milieu and external environment. Kidney failure is known to disrupt a number of homeostatic mechanisms that control serum calcium and normal bone metabolism. However, our understanding of calcium balance throughout the stages of chronic kidney disease is limited and the concept of balance itself, especially with a cation as complex as calcium, is often misunderstood. Both negative and positive calcium balance have important implications in patients with chronic kidney disease, where negative balance may increase risk of osteoporosis and fracture and positive balance may increase risk of vascular calcification and cardiovascular events. Here, we examine the state of current knowledge about calcium balance in adults throughout the stages of chronic kidney disease and discuss recommendations for clinical strategies to maintain balance as well as future research needs in this area. Recent calcium balance studies in adult patients with chronic kidney disease show that neutral calcium balance is achieved with calcium intake near the recommended daily allowance. Increases in calcium through diet or supplements cause high positive calcium balance, which may put patients at risk for vascular calcification. However, heterogeneity in calcium balance exists among these patients. Given the available calcium balance data in this population, it appears clinically prudent to aim for recommended calcium intakes around 1000 mg/day to achieve neutral calcium balance and avoid adverse effects of either negative or positive calcium balance. Assessment of patients' dietary calcium intake could further equip clinicians to make individualized recommendations for meeting recommended intakes.

Human Impacts on the Hydrologic Cycle: Comparing Global Climate Change and Local Water Management

Science.gov (United States)

Ferguson, I. M.; Maxwell, R. M.

2010-12-01

Anthropogenic climate change is significantly altering the hydrologic cycle at global and regional scales, with potentially devastating impacts on water resources. Recent studies demonstrate that hydrologic response to climate change will depend on local-scale feedbacks between groundwater, surface water, and land surface processes. These studies suggest that local water management practices that alter the quantity and distribution of water in the terrestrial system—e.g., groundwater pumping and irrigation—may also feed back across the hydrologic cycle, with impacts on land-atmosphere fluxes and thus weather and climate. Here we use an integrated hydrologic model to compare the impacts of large-scale climate change and local water management practices on water and energy budgets at local and watershed scales. We consider three climate scenarios (hot, hot+wet, and hot+dry) and three management scenarios (pumping only, irrigation only, and pumping+irrigation). Results demonstrate that impacts of local water management on basin-integrated groundwater storage, evapotranspiration, and stream discharge are comparable to those of changing climate conditions. However, impacts of climate change are shown to have a smaller magnitude and greater spatial extent, while impacts of pumping and irrigation are shown to have a greater magnitude but are local to areas where pumping and irrigation occur. These results have important implications regarding the scales of human impacts on both water resources and climate and the sustainability of water resources.

Dynamical patterns of calcium signaling in a functional model of neuron-astrocyte networks

DEFF Research Database (Denmark)

Postnov, D.E.; Koreshkov, R.N.; Brazhe, N.A.

2009-01-01

We propose a functional mathematical model for neuron-astrocyte networks. The model incorporates elements of the tripartite synapse and the spatial branching structure of coupled astrocytes. We consider glutamate-induced calcium signaling as a specific mode of excitability and transmission...... in astrocytic-neuronal networks. We reproduce local and global dynamical patterns observed experimentally....

Global Carbon Budget 2017

NARCIS (Netherlands)

Le Quere, Corinne; Andrew, Robbie M.; Friedlingstein, Pierre; Sitch, Stephen; Pongratz, Julia; Manning, Andrew C.; Korsbakken, Jan Ivar; Peters, Glen P.; Canadell, Josep G.; Jackson, Robert B.; Boden, Thomas A.; Tans, Pieter P.; Andrews, Oliver D.; Arora, Vivek K.; Bakker, Dorothee C. E.; Barbero, Leticia; Becker, Meike; Betts, Richard A.; Bopp, Laurent; Chevallier, Frederic; Chini, Louise P.; Ciais, Philippe; Cosca, Catherine E.; Cross, Jessica; Currie, Kim; Gasser, Thomas; Harris, Ian; Hauck, Judith; Haverd, Vanessa; Houghton, Richard A.; Hunt, Christopher W.; Hurtt, George; Ilyina, Tatiana; Jain, Atul K.; Kato, Etsushi; Kautz, Markus; Keeling, Ralph F.; Goldewijk, Kees Klein; Koertzinger, Arne; Landschuetzer, Peter; Lefevre, Nathalie; Lenton, Andrew; Lienert, Sebastian; Lima, Ivan; Lombardozzi, Danica; Metzl, Nicolas; Millero, Frank; Monteiro, Pedro M. S.; Munro, David R.; Nabel, Julia E. M. S.; Nakaoka, Shin-ichiro; Nojiri, Yukihiro; Padin, X. Antonio; Peregon, Anna; Pfeil, Benjamin; Pierrot, Denis; Poulter, Benjamin; Rehder, Gregor; Reimer, Janet; Roedenbeck, Christian; Schwinger, Jorg; Seferian, Roland; Skjelvan, Ingunn; Stocker, Benjamin D.; Tian, Hanqin; Tilbrook, Bronte; Tubiello, Francesco N.; van der Laan-Luijkx, Ingrid T.; van der Werf, Guido R.; van Heuven, Steven; Viovy, Nicolas; Vuichard, Nicolas; Walker, Anthony P.; Watson, Andrew J.; Wiltshire, Andrew J.; Zaehle, Soenke; Zhu, Dan

2018-01-01

Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere - the "global carbon budget" - is important to better understand the global carbon cycle, support the development of climate policies, and project

Global Carbon Budget 2016

NARCIS (Netherlands)

Le Quéré, Corinne; Andrew, Robbie M.; Canadell, Josep G.; Sitch, Stephen; Ivar Korsbakken, Jan; Peters, Glen P.; Manning, Andrew C.; Boden, Thomas A.; Tans, Pieter P.; Houghton, Richard A.; Keeling, Ralph F.; Alin, Simone; Andrews, Oliver D.; Anthoni, Peter; Barbero, Leticia; Bopp, Laurent; Chevallier, Frédéric; Chini, Louise P.; Ciais, Philippe; Currie, Kim; Delire, Christine; Doney, Scott C.; Friedlingstein, Pierre; Gkritzalis, Thanos; Harris, Ian A; Hauck, Judith; Haverd, Vanessa; Hoppema, Mario; Klein Goldewijk, Kees; Jain, Atul K.; Kato, Etsushi; Körtzinger, Arne; Landschützer, Peter; Lefèvre, Nathalie; Lenton, Andrew; Lienert, Sebastian; Lombardozzi, Danica; Melton, Joe R.; Metzl, Nicolas; Millero, Frank; Monteiro, Pedro M S; Munro, David R.; Nabel, Julia E M S; Nakaoka, Shin Ichiro; O'Brien, Kevin; Olsen, Are; Omar, Abdirahman M.; Ono, Tsuneo; Pierrot, Denis; Poulter, Benjamin; Rödenbeck, Christian; Salisbury, Joe; Schuster, Ute; Schwinger, Jörg; Séférian, Roland; Skjelvan, Ingunn; Stocker, Benjamin D.; Sutton, Adrienne J.; Takahashi, Taro; Tian, Hanqin; Tilbrook, Bronte; Van Der Laan-Luijkx, Ingrid T.; Van Der Werf, Guido R.; Viovy, Nicolas; Walker, Anthony P.; Wiltshire, Andrew J.; Zaehle, Sönke

2016-01-01

Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere-the "global carbon budget"-is important to better understand the global carbon cycle, support the development of climate policies, and project future

Implementation of methane cycling for deep time, global warming simulations with the DCESS Earth System Model (Version 1.2)

DEFF Research Database (Denmark)

Shaffer, Gary; Villanueva, Esteban Fernández; Rondanelli, Roberto

2017-01-01

Geological records reveal a number of ancient, large and rapid negative excursions of carbon-13 isotope. Such excursions can only be explained by massive injections of depleted carbon to the Earth System over a short duration. These injections may have forced strong global warming events, sometimes....... With this improved DCESS model version and paleo-reconstructions, we are now better armed to gauge the amounts, types, time scales and locations of methane injections driving specific, observed deep time, global warming events......., or from warming-induced dissociation of methane hydrate, a solid compound of methane and water found in ocean sediments. As a consequence of the ubiquity and importance of methane in major Earth events, Earth System models should include a comprehensive treatment of methane cycling but such a treatment...

Fenoprofen calcium overdose

Science.gov (United States)

... page: //medlineplus.gov/ency/article/002649.htm Fenoprofen calcium overdose To use the sharing features on this page, please enable JavaScript. Fenoprofen calcium is a type of medicine called a nonsteroidal ...

Effect of oral calcium and calcium + fluoride treatments on mouse bone properties during suspension

Science.gov (United States)

Simske, S. J.; Luttges, M. W.; Allen, K. A.; Spooner, B. S. (Principal Investigator)

1992-01-01

The bone effects of oral dosages of calcium chloride with or without supplementary sodium fluoride were assessed in antiorthostatically suspended mice. Two calcium dosages were used to replace half (3.1 mM) or all(6.3 mM) of the dietary calcium lost due to reduced food intake by the suspended mice. Two groups of 6.3 mM CaCl2-treated mice were additionally treated with 0.25 or 2.5 mM NaF. The results indicate that supplementation of the mouse drinking water with calcium salts prevents bone changes induced by short-term suspension, while calcium salts in combination with fluoride are less effective as fluoride dosage increases. However, the calcium supplements change the relationship between the femur mechanical properties and the mineral composition of the bone. Because of this, it appears that oral calcium supplements are effective through a mechanism other than simple dietary supplementation and may indicate a dependence of bone consistency on systemic and local fluid conditions.

A strategy of precipitated calcium carbonate (CaCO{sub 3}) fillers for enhancing the mechanical properties of polypropylene polymers

Energy Technology Data Exchange (ETDEWEB)

Thenepalli, Thriveni; Ahn, Ji Whan [Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon (Korea, Republic of); Ahn, Young Jun; Han, Choon [Kwangwoon University, Seoul (Korea, Republic of); Ramakrishna, Chilakala [Hanil Cement, Danyang (Korea, Republic of)

2015-06-15

A wide variety of fillers are currently used in more than twenty types of polymer resins, although four of them alone (polypropylene, polyamides, thermoplastic polyesters, and polyvinyl chloride) account for 90% of the market of mineral fillers in plastics. Polypropylene (PP) and PVC dominate the market for calcium carbonate. PP is a versatile reinforcement material that can meet engineering and structural specifications and is widely used for automotive components, home appliances, and industrial applications. Talc, mica, clay, kaolin, wollastonite, calcium carbonates, feldspar, aluminum hydroxide, glass fibers, and natural fibers are commonly used in fillers. Among these, calcium carbonate (both natural and synthetic) is the mos abundant and affords the possibility of improved surface finishing, control over the manufacture of products, and increased electric resistance and impact resistance. Meeting the global challenge to reduce the weight of vehicles by using plastics is a significant issue. The current the global plastic and automobile industry cannot survive without fillers, additives, and reinforcements. Polypropylene is a major component of the modern plastic industry, and currently is used in dashboards, wheel covers, and some engine parts in automobiles. This article reports that the use of calcium carbonate fillers with polypropylene is the best choice to enhance the mechanical properties of plastic parts used in automobiles.

Preparation of cerium doped calcium pyrophosphate: Study of luminescent behavior

Energy Technology Data Exchange (ETDEWEB)

Lozano, I.B., E-mail: ivonne.berenice@gmail.com [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, 11500 México D.F., México (Mexico); Roman-Lopez, J. [CONACYT Research Fellow-Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A.P. 70-543, 04510 México D.F., México (Mexico); Sosa, R. [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, 09340 México D.F., México (Mexico); Díaz-Góngora, J.A.I [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, 11500 México D.F., México (Mexico); Azorín, J. [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, 09340 México D.F., México (Mexico)

2016-05-15

Thermoluminescent (TL) and photoluminescent (PL) band emissions of cerium doped calcium pyrophosphate (Ca{sub 2}O{sub 7}P{sub 2}:Ce{sup 3+}) were studied. Wet precipitation method was used to synthesize calcium pyrophosphate, doped with Ce{sup 3+} (1.0 at%) impurities, from orthophosphoric acid and calcium acetate, as raw materials. The effect of temperature annealing at 800 and 900 °C was investigated. X-Ray diffraction (XRD) and Scanning Electron Microscope (SEM) were used to characterize both as-precipitated and annealed powders samples. The PL emission spectrum of samples annealed at 900 °C displayed characteristics 5d–4f transitions of Ce{sup 3+} at 333 nm and 360 nm. TL measurements were carried out on as-precipitated and annealed samples from room temperature (RT) up to 350 °C. The TL results of annealed samples showed complex TL glow curves, a linear response in the absorbed dose range of 0.5–5 Gy and a good reproducibility after 10 cycles of irradiation-readout. The complex TL glow curves of annealed samples were analyzed by the methods of T{sub max}–T{sub Stop}, Initial Rise (IR) and Computational Glow-Curve Deconvolution (CGCD) assuming a General Order Kinetic (GOK).

Global change and biogeochemical cycles: The south Asia region

Digital Repository Service at National Institute of Oceanography (India)

Mitra, A.P.; DileepKumar, M.; Kumar, K.R.; Abrol, Y.P.; Kalra, N.; Velayutham, M.; Naqvi, S.W.A.

stream_size 33 stream_content_type text/plain stream_name Global-Region_Linkage_Earth_Syst_2002_75.pdf.txt stream_source_info Global-Region_Linkage_Earth_Syst_2002_75.pdf.txt Content-Encoding ISO-8859-1 Content-Type text...

Structures of apicomplexan calcium-dependent protein kinases reveal mechanism of activation by calcium

Energy Technology Data Exchange (ETDEWEB)

Wernimont, Amy K; Artz, Jennifer D.; Jr, Patrick Finerty; Lin, Yu-Hui; Amani, Mehrnaz; Allali-Hassani, Abdellah; Senisterra, Guillermo; Vedadi, Masoud; Tempel, Wolfram; Mackenzie, Farrell; Chau, Irene; Lourido, Sebastian; Sibley, L. David; Hui, Raymond (Toronto); (WU-MED)

2010-09-21

Calcium-dependent protein kinases (CDPKs) have pivotal roles in the calcium-signaling pathway in plants, ciliates and apicomplexan parasites and comprise a calmodulin-dependent kinase (CaMK)-like kinase domain regulated by a calcium-binding domain in the C terminus. To understand this intramolecular mechanism of activation, we solved the structures of the autoinhibited (apo) and activated (calcium-bound) conformations of CDPKs from the apicomplexan parasites Toxoplasma gondii and Cryptosporidium parvum. In the apo form, the C-terminal CDPK activation domain (CAD) resembles a calmodulin protein with an unexpected long helix in the N terminus that inhibits the kinase domain in the same manner as CaMKII. Calcium binding triggers the reorganization of the CAD into a highly intricate fold, leading to its relocation around the base of the kinase domain to a site remote from the substrate binding site. This large conformational change constitutes a distinct mechanism in calcium signal-transduction pathways.

Live Imaging of Calcium Dynamics during Axon Degeneration Reveals Two Functionally Distinct Phases of Calcium Influx

Science.gov (United States)

Yamagishi, Yuya; Tessier-Lavigne, Marc

2015-01-01

Calcium is a key regulator of axon degeneration caused by trauma and disease, but its specific spatial and temporal dynamics in injured axons remain unclear. To clarify the function of calcium in axon degeneration, we observed calcium dynamics in single injured neurons in live zebrafish larvae and tested the temporal requirement for calcium in zebrafish neurons and cultured mouse DRG neurons. Using laser axotomy to induce Wallerian degeneration (WD) in zebrafish peripheral sensory axons, we monitored calcium dynamics from injury to fragmentation, revealing two stereotyped phases of axonal calcium influx. First, axotomy triggered a transient local calcium wave originating at the injury site. This initial calcium wave only disrupted mitochondria near the injury site and was not altered by expression of the protective WD slow (WldS) protein. Inducing multiple waves with additional axotomies did not change the kinetics of degeneration. In contrast, a second phase of calcium influx occurring minutes before fragmentation spread as a wave throughout the axon, entered mitochondria, and was abolished by WldS expression. In live zebrafish, chelating calcium after the first wave, but before the second wave, delayed the progress of fragmentation. In cultured DRG neurons, chelating calcium early in the process of WD did not alter degeneration, but chelating calcium late in WD delayed fragmentation. We propose that a terminal calcium wave is a key instructive component of the axon degeneration program. SIGNIFICANCE STATEMENT Axon degeneration resulting from trauma or neurodegenerative disease can cause devastating deficits in neural function. Understanding the molecular and cellular events that execute axon degeneration is essential for developing treatments to address these conditions. Calcium is known to contribute to axon degeneration, but its temporal requirements in this process have been unclear. Live calcium imaging in severed zebrafish neurons and temporally controlled

Global qualitative analysis of a quartic ecological model

NARCIS (Netherlands)

Broer, Hendrik; Gaiko, Valery A.

2010-01-01

in this paper we complete the global qualitative analysis of a quartic ecological model. In particular, studying global bifurcations of singular points and limit cycles, we prove that the corresponding dynamical system has at most two limit cycles. (C) 2009 Elsevier Ltd. All rights reserved.

Calcium isotope fractionation between soft and mineralized tissues as a monitor of calcium use in vertebrates

Science.gov (United States)

Skulan, Joseph; DePaolo, Donald J.

1999-01-01

Calcium from bone and shell is isotopically lighter than calcium of soft tissue from the same organism and isotopically lighter than source (dietary) calcium. When measured as the 44Ca/40Ca isotopic ratio, the total range of variation observed is 5.5‰, and as much as 4‰ variation is found in a single organism. The observed intraorganismal calcium isotopic variations and the isotopic differences between tissues and diet indicate that isotopic fractionation occurs mainly as a result of mineralization. Soft tissue calcium becomes heavier or lighter than source calcium during periods when there is net gain or loss of mineral mass, respectively. These results suggest that variations of natural calcium isotope ratios in tissues may be useful for assessing the calcium and mineral balance of organisms without introducing isotopic tracers. PMID:10570137

Nitrogen cycling in corals: the key to understanding holobiont functioning?

KAUST Repository

Rädecker, Nils

2015-04-01

Corals are animals that form close mutualistic associations with endosymbiotic photosynthetic algae of the genus Symbiodinium. Together they provide the calcium carbonate framework of coral reef ecosystems. The importance of the microbiome (i.e., bacteria, archaea, fungi, and viruses) to holobiont functioning has only recently been recognized. Given that growth and density of Symbiodinium within the coral host is highly dependent on nitrogen availability, nitrogen-cycling microbes may be of fundamental importance to the stability of the coral–algae symbiosis and holobiont functioning, in particular under nutrient-enriched and -depleted scenarios. We summarize what is known about nitrogen cycling in corals and conclude that disturbance of microbial nitrogen cycling may be tightly linked to coral bleaching and disease.

Nitrogen cycling in corals: the key to understanding holobiont functioning?

KAUST Repository

Rä decker, Nils; Pogoreutz, Claudia; Voolstra, Christian R.; Wiedenmann, Jö rg; Wild, Christian

2015-01-01

Corals are animals that form close mutualistic associations with endosymbiotic photosynthetic algae of the genus Symbiodinium. Together they provide the calcium carbonate framework of coral reef ecosystems. The importance of the microbiome (i.e., bacteria, archaea, fungi, and viruses) to holobiont functioning has only recently been recognized. Given that growth and density of Symbiodinium within the coral host is highly dependent on nitrogen availability, nitrogen-cycling microbes may be of fundamental importance to the stability of the coral–algae symbiosis and holobiont functioning, in particular under nutrient-enriched and -depleted scenarios. We summarize what is known about nitrogen cycling in corals and conclude that disturbance of microbial nitrogen cycling may be tightly linked to coral bleaching and disease.

Global Carbon Budget 2016

NARCIS (Netherlands)

Quéré, Le Corinne; Andrew, Robbie M.; Canadell, Josep G.; Sitch, Stephen; Korsbakken, Jan Ivar; Peters, Glen P.; Manning, Andrew C.; Boden, Thomas A.; Tans, Pieter P.; Houghton, Richard A.; Keeling, Ralph F.; Alin, Simone; Andrews, Oliver D.; Anthoni, Peter; Barbero, Leticia; Bopp, Laurent; Chevallier, Frédéric; Chini, Louise P.; Ciais, Philippe; Currie, Kim; Delire, Christine; Doney, Scott C.; Friedlingstein, Pierre; Gkritzalis, Thanos; Harris, Ian; Hauck, Judith; Haverd, Vanessa; Hoppema, Mario; Klein Goldewijk, Kees; Jain, Atul K.; Kato, Etsushi; Körtzinger, Arne; Landschützer, Peter; Lefèvre, Nathalie; Lenton, Andrew; Lienert, Sebastian; Lombardozzi, Danica; Melton, Joe R.; Metzl, Nicolas; Millero, Frank; Monteiro, Pedro M.S.; Munro, David R.; Nabel, Julia E.M.S.; Nakaoka, S.; O'Brien, Kevin; Olsen, Are; Omar, Abdirahman M.; Ono, Tsuneo; Pierrot, Denis; Poulter, Benjamin; Rödenbeck, Christian; Salisbury, Joe; Schuster, Ute; Schwinger, Jörg; Séférian, Roland; Skjelvan, Ingunn; Stocker, Benjamin D.; Sutton, Adrienne J.; Takahashi, Taro; Tian, Hanqin; Tilbrook, Bronte; Laan-Luijkx, van der Ingrid T.; Werf, van der Guido R.; Viovy, Nicolas; Walker, Anthony P.; Wiltshire, Andrew J.; Zaehle, Sönke

2016-01-01

Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere – the “global carbon budget” – is important to better understand the global carbon cycle, support the development of climate policies, and project

Synthesis of Portland cement and calcium sulfoaluminate-belite cement for sustainable development and performance

Science.gov (United States)

Chen, Irvin Allen

Portland cement concrete, the most widely used manufactured material in the world, is made primarily from water, mineral aggregates, and portland cement. The production of portland cement is energy intensive, accounting for 2% of primary energy consumption and 5% of industrial energy consumption globally. Moreover, portland cement manufacturing contributes significantly to greenhouse gases and accounts for 5% of the global CO2 emissions resulting from human activity. The primary objective of this research was to explore methods of reducing the environmental impact of cement production while maintaining or improving current performance standards. Two approaches were taken, (1) incorporation of waste materials in portland cement synthesis, and (2) optimization of an alternative environmental friendly binder, calcium sulfoaluminate-belite cement. These approaches can lead to less energy consumption, less emission of CO2, and more reuse of industrial waste materials for cement manufacturing. In the portland cement part of the research, portland cement clinkers conforming to the compositional specifications in ASTM C 150 for Type I cement were successfully synthesized from reagent-grade chemicals with 0% to 40% fly ash and 0% to 60% slag incorporation (with 10% intervals), 72.5% limestone with 27.5% fly ash, and 65% limestone with 35% slag. The synthesized portland cements had similar early-age hydration behavior to commercial portland cement. However, waste materials significantly affected cement phase formation. The C3S--C2S ratio decreased with increasing amounts of waste materials incorporated. These differences could have implications on proportioning of raw materials for cement production when using waste materials. In the calcium sulfoaluminate-belite cement part of the research, three calcium sulfoaluminate-belite cement clinkers with a range of phase compositions were successfully synthesized from reagent-grade chemicals. The synthesized calcium sulfoaluminate

Representing leaf and root physiological traits in CLM improves global carbon and nitrogen cycling predictions

Science.gov (United States)

Ghimire, Bardan; Riley, William J.; Koven, Charles D.; Mu, Mingquan; Randerson, James T.

2016-06-01

In many ecosystems, nitrogen is the most limiting nutrient for plant growth and productivity. However, current Earth System Models (ESMs) do not mechanistically represent functional nitrogen allocation for photosynthesis or the linkage between nitrogen uptake and root traits. The current version of CLM (4.5) links nitrogen availability and plant productivity via (1) an instantaneous downregulation of potential photosynthesis rates based on soil mineral nitrogen availability, and (2) apportionment of soil nitrogen between plants and competing nitrogen consumers assumed to be proportional to their relative N demands. However, plants do not photosynthesize at potential rates and then downregulate; instead photosynthesis rates are governed by nitrogen that has been allocated to the physiological processes underpinning photosynthesis. Furthermore, the role of plant roots in nutrient acquisition has also been largely ignored in ESMs. We therefore present a new plant nitrogen model for CLM4.5 with (1) improved representations of linkages between leaf nitrogen and plant productivity based on observed relationships in a global plant trait database and (2) plant nitrogen uptake based on root-scale Michaelis-Menten uptake kinetics. Our model improvements led to a global bias reduction in GPP, LAI, and biomass of 70%, 11%, and 49%, respectively. Furthermore, water use efficiency predictions were improved conceptually, qualitatively, and in magnitude. The new model's GPP responses to nitrogen deposition, CO2 fertilization, and climate also differed from the baseline model. The mechanistic representation of leaf-level nitrogen allocation and a theoretically consistent treatment of competition with belowground consumers led to overall improvements in global carbon cycling predictions.

Terrestrial nitrogen cycling in Earth system models revisited

Science.gov (United States)

Stocker, Benjamin D; Prentice, I. Colin; Cornell, Sarah; Davies-Barnard, T; Finzi, Adrien; Franklin, Oskar; Janssens, Ivan; Larmola, Tuula; Manzoni, Stefano; Näsholm, Torgny; Raven, John; Rebel, Karin; Reed, Sasha C.; Vicca, Sara; Wiltshire, Andy; Zaehle, Sönke

2016-01-01

Understanding the degree to which nitrogen (N) availability limits land carbon (C) uptake under global environmental change represents an unresolved challenge. First-generation ‘C-only’vegetation models, lacking explicit representations of N cycling,projected a substantial and increasing land C sink under rising atmospheric CO2 concentrations. This prediction was questioned for not taking into account the potentially limiting effect of N availability, which is necessary for plant growth (Hungate et al.,2003). More recent global models include coupled C and N cycles in land ecosystems (C–N models) and are widely assumed to be more realistic. However, inclusion of more processes has not consistently improved their performance in capturing observed responses of the global C cycle (e.g. Wenzel et al., 2014). With the advent of a new generation of global models, including coupled C, N, and phosphorus (P) cycling, model complexity is sure to increase; but model reliability may not, unless greater attention is paid to the correspondence of model process representations ande mpirical evidence. It was in this context that the ‘Nitrogen Cycle Workshop’ at Dartington Hall, Devon, UK was held on 1–5 February 2016. Organized by I. Colin Prentice and Benjamin D. Stocker (Imperial College London, UK), the workshop was funded by the European Research Council,project ‘Earth system Model Bias Reduction and assessing Abrupt Climate change’ (EMBRACE). We gathered empirical ecologists and ecosystem modellers to identify key uncertainties in terrestrial C–N cycling, and to discuss processes that are missing or poorly represented in current models.

Simulating antler growth and energy, nitrogen, calcium and phosphorus metabolism in caribou

Directory of Open Access Journals (Sweden)

Ron Moen

1998-03-01

Full Text Available We added antler growth and mineral metabolism modules to a previously developed energetics model for ruminants to simulate energy and mineral balance of male and female caribou throughout an annual cycle. Body watet, fat, protein, and ash are monitored on a daily time step, and energy costs associated with reproduction and body mass changes are simulated. In order to simulate antler growth, we had to predict calcium and phosphorus metabolism as it is affected by antler growth, gestation, and lactation. We used data on dietary digestibility, protein, calcium and phosphorus content, and seasonal patterns in body mass to predict the energy, nitrogen, calcium, and phosphorus balances of a "generic" male and female caribou. Antler growth in males increased energy requirements during antler growth by 8 to 16%, depending on the efficiency with which energy was used for antler growth. Female energy requirements for antler growth were proportionately much smaller because of the smaller size of female antlers. Protein requirements for antler growth in both males and females were met by forage intake. Calcium and phosphorus must be resorbed from bone during peak antler growth in males, when > 25 g/day of calcium and > 12 g/day of phosphorus are being deposited in antlers. Females are capable of meeting calcium needs during antler growth without bone resorption, but phosphorus was resorbed from bone during the final stages of antler mineralization. After energy, phosphorus was most likely to limit growth of antlers for both males and females in our simulations. Input parameters can be easily changed to represent caribou from specific geographic regions in which dietary nutrient content or body mass patterns differ from those in our "generic" caribou. The model can be used to quantitatively analyze the evolutionary basis for development of antlers in female caribou, and the relationship between body mass and antler size in the Cervidae.

Cardiovascular Effects of Calcium Supplements

Directory of Open Access Journals (Sweden)

Ian R. Reid

2013-07-01

Full Text Available Calcium supplements reduce bone turnover and slow the rate of bone loss. However, few studies have demonstrated reduced fracture incidence with calcium supplements, and meta-analyses show only a 10% decrease in fractures, which is of borderline statistical and clinical significance. Trials in normal older women and in patients with renal impairment suggest that calcium supplements increase the risk of cardiovascular disease. To further assess their safety, we recently conducted a meta-analysis of trials of calcium supplements, and found a 27%–31% increase in risk of myocardial infarction, and a 12%–20% increase in risk of stroke. These findings are robust because they are based on pre-specified analyses of randomized, placebo-controlled trials and are consistent across the trials. Co-administration of vitamin D with calcium does not lessen these adverse effects. The increased cardiovascular risk with calcium supplements is consistent with epidemiological data relating higher circulating calcium concentrations to cardiovascular disease in normal populations. There are several possible pathophysiological mechanisms for these effects, including effects on vascular calcification, vascular cells, blood coagulation and calcium-sensing receptors. Thus, the non-skeletal risks of calcium supplements appear to outweigh any skeletal benefits, and are they appear to be unnecessary for the efficacy of other osteoporosis treatments.

Dietary Calcium Intake and Calcium Supplementation in Hungarian Patients with Osteoporosis

Directory of Open Access Journals (Sweden)

Gábor Speer

2013-01-01

Full Text Available Purpose. Adequate calcium intake is the basis of osteoporosis therapy—when this proves insufficient, even specific antiosteoporotic agents cannot exert their actions properly. Methods. Our representative survey analyzed the dietary intake and supplementation of calcium in 8033 Hungarian female and male (mean age: 68 years (68.01 (CI95: 67.81–68.21 patients with osteoporosis. Results. Mean intake from dietary sources was 665±7.9 mg (68.01 (CI95: 67.81–68.21 daily. A significant positive relationship could be detected between total dietary calcium intake and lumbar spine BMD (P=0.045, whereas such correlation could not be demonstrated with femoral T-score. Milk consumption positively correlated with femur (P=0.041, but not with lumbar BMD. The ingestion of one liter of milk daily increased the T-score by 0.133. Average intake from supplementation was 558±6.2 mg (68.01 (CI95: 67.81–68.21 daily. The cumulative dose of calcium—from both dietary intake and supplementation—was significantly associated with lumbar (r=0.024, P=0.049, but not with femur BMD (r=0.021, P=0.107. The currently recommended 1000–1500 mg total daily calcium intake was achieved in 34.5% of patients only. It was lower than recommended in 47.8% of the cases and substantially higher in 17.7% of subjects. Conclusions. We conclude that calcium intake in Hungarian osteoporotic patients is much lower than the current recommendation, while routinely applied calcium supplementation will result in inappropriately high calcium intake in numerous patients.

Regionalization of land use impact models for life cycle assessment: Recommendations for their use on the global scale and their applicability to Brazil

Energy Technology Data Exchange (ETDEWEB)

Pavan, Ana Laura Raymundo, E-mail: laurarpavan@gmail.com [Center for Water Resource and Environmental Studies, São Carlos School of Engineering, University of São Paulo, Av. Trabalhador São-Carlense 400, São Carlos 13566-590, SP (Brazil); Ometto, Aldo Roberto [Center for Water Resource and Environmental Studies, São Carlos School of Engineering, University of São Paulo, Av. Trabalhador São-Carlense 400, São Carlos 13566-590, SP (Brazil); Department of Production Engineering, São Carlos School of Engineering, University of São Paulo, Av. Trabalhador São-Carlense 400, São Carlos 13566-590, SP (Brazil)

2016-09-15

Life Cycle Assessment (LCA) is the main technique for evaluate the environmental impacts of product life cycles. A major challenge in the field of LCA is spatial and temporal differentiation in Life Cycle Impact Assessment (LCIA) methods, especially impacts resulting from land occupation and land transformation. Land use characterization modeling has advanced considerably over the last two decades and many approaches have recently included crucial aspects such as geographic differentiation. Nevertheless, characterization models have so far not been systematically reviewed and evaluated to determine their applicability to South America. Given that Brazil is the largest country in South America, this paper analyzes the main international characterization models currently available in the literature, with a view to recommending regionalized models applicable on a global scale for land use life cycle impact assessments, and discusses their feasibility for regionalized assessment in Brazil. The analytical methodology involves classification based on the following criteria: midpoint/endpoint approach, scope of application, area of data collection, biogeographical differentiation, definition of recovery time and reference situation; followed by an evaluation of thirteen scientific robustness and environmental relevance subcriteria. The results of the scope of application are distributed among 25% of the models developed for the European context, and 50% have a global scope. There is no consensus in the literature about the definition of parameters such biogeographical differentiation and reference situation, and our review indicates that 35% of the models use ecoregion division while 40% use the concept of potential natural vegetation. Four characterization models show high scores in terms of scientific robustness and environmental relevance. These models are recommended for application in land use life cycle impact assessments, and also to serve as references for the

Calcium oxalate stone and gout.

Science.gov (United States)

Marickar, Y M Fazil

2009-12-01

Gout is well known to be produced by increased uric acid level in blood. The objective of this paper is to assess the relationship between gout and calcium oxalate stone formation in the humans. 48 patients with combination of gout and calcium oxalate stone problem were included. The biochemical values of this group were compared with 38 randomly selected uric acid stone patients with gout, 43 stone patients with gout alone, 100 calcium oxalate stone patients without gout and 30 controls, making a total of 259 patients. Various biochemical parameters, namely serum calcium, phosphorus and uric acid and 24-h urine calcium, phosphorus, uric acid, oxalate, citrate and magnesium were analysed. ANOVA and Duncan's multiple-range tests were performed to assess statistical significance of the variations. The promoters of stone formation, namely serum calcium (P stone patients and gouty calcium oxalate stone patients compared to the non-gouty patients and controls. Urine oxalate (P stones patients. The inhibitor urine citrate (P stone gouty patients, followed by the gouty uric acid stone formers and gouty calcium oxalate stone patients. The high values of promoters, namely uric acid and calcium in the gouty stone patients indicate the tendency for urinary stone formation in the gouty stone patients. There is probably a correlation between gout and calcium oxalate urinary stone. We presume this mechanism is achieved through the uric acid metabolism. The findings point to the summation effect of metabolic changes in development of stone disease.

Purification and reconstitution of the calcium antagonist receptor of the voltage-sensitive calcium channel

International Nuclear Information System (INIS)

Curtis, B.M.

1986-01-01

Treatment with digitonin solubilized the calcium antagonist receptor as a stable complex with [ 3 H]nitrendipine from rat brain membranes. The solubilized complex retains allosteric coupling to binding sites for diltiazem, verapamil, and inorganic calcium antagonist sites. The calcium antagonist receptor from cardiac sarcolemma and the transverse-tubule membrane of skeletal muscle is also efficiently solubilized with digitonin and the receptor in all three tissues is a large glycoprotein with a sedimentation coefficient of 20 S. The T-tubule calcium antagonist receptor complex was extensively purified by a combination of chromatography on WGA-Sepharose, ion exchange chromatography, and sedimentation on sucrose gradients to yield preparations estimated to be 41% homogeneous by specific activity and 63% homogeneous by SDS gel electrophoresis. Analysis of SDS gels detect three polypeptides termed α(Mr 135,000), β(Mr 50,000), and γ(Mr 32,000) as noncovalently associated subunits of the calcium antagonist receptor. The α and γ subunits are glycosylated polypeptides, and the molecular weight of the core polypeptides are 108,000 and 24,000 respectively. The calcium antagonist receptor was reconstituted into a phospholipid bilayer by adding CHAPS and exogeneous lipid to the purified receptor followed by rapid detergent removal. This procedure resulted in the incorporation of 45% of the calcium antagonist receptor into closed phospholipid vesicles. Data suggests that the α, β, and γ subunits of the T-tubule calcium antagonist receptor are sufficient to form a functional calcium channel

Global nuclear material control model

International Nuclear Information System (INIS)

Dreicer, J.S.; Rutherford, D.A.

1996-01-01

The nuclear danger can be reduced by a system for global management, protection, control, and accounting as part of a disposition program for special nuclear materials. The development of an international fissile material management and control regime requires conceptual research supported by an analytical and modeling tool that treats the nuclear fuel cycle as a complete system. Such a tool must represent the fundamental data, information, and capabilities of the fuel cycle including an assessment of the global distribution of military and civilian fissile material inventories, a representation of the proliferation pertinent physical processes, and a framework supportive of national or international perspective. They have developed a prototype global nuclear material management and control systems analysis capability, the Global Nuclear Material Control (GNMC) model. The GNMC model establishes the framework for evaluating the global production, disposition, and safeguards and security requirements for fissile nuclear material

Why Calcium? How Calcium Became the Best Communicator*

OpenAIRE

Carafoli, Ernesto; Krebs, Joachim

2016-01-01

Calcium carries messages to virtually all important functions of cells. Although it was already active in unicellular organisms, its role became universally important after the transition to multicellular life. In this Minireview, we explore how calcium ended up in this privileged position. Most likely its unique coordination chemistry was a decisive factor as it makes its binding by complex molecules particularly easy even in the presence of large excesses of other cations,...

Calcium-Induced calcium release during action potential firing in developing inner hair cells.

Science.gov (United States)

Iosub, Radu; Avitabile, Daniele; Grant, Lisa; Tsaneva-Atanasova, Krasimira; Kennedy, Helen J

2015-03-10

In the mature auditory system, inner hair cells (IHCs) convert sound-induced vibrations into electrical signals that are relayed to the central nervous system via auditory afferents. Before the cochlea can respond to normal sound levels, developing IHCs fire calcium-based action potentials that disappear close to the onset of hearing. Action potential firing triggers transmitter release from the immature IHC that in turn generates experience-independent firing in auditory neurons. These early signaling events are thought to be essential for the organization and development of the auditory system and hair cells. A critical component of the action potential is the rise in intracellular calcium that activates both small conductance potassium channels essential during membrane repolarization, and triggers transmitter release from the cell. Whether this calcium signal is generated by calcium influx or requires calcium-induced calcium release (CICR) is not yet known. IHCs can generate CICR, but to date its physiological role has remained unclear. Here, we used high and low concentrations of ryanodine to block or enhance CICR to determine whether calcium release from intracellular stores affected action potential waveform, interspike interval, or changes in membrane capacitance during development of mouse IHCs. Blocking CICR resulted in mixed action potential waveforms with both brief and prolonged oscillations in membrane potential and intracellular calcium. This mixed behavior is captured well by our mathematical model of IHC electrical activity. We perform two-parameter bifurcation analysis of the model that predicts the dependence of IHCs firing patterns on the level of activation of two parameters, the SK2 channels activation and CICR rate. Our data show that CICR forms an important component of the calcium signal that shapes action potentials and regulates firing patterns, but is not involved directly in triggering exocytosis. These data provide important insights

21 CFR 573.260 - Calcium silicate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 573.260 Section 573.260 Food and... Listing § 573.260 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely used as an anticaking agent in animal feed, provided that the amount of calcium silicate does not...

A global model of carbon, nitrogen and phosphorus cycles for the terrestrial biosphere

Directory of Open Access Journals (Sweden)

Y. P. Wang

2010-07-01

Full Text Available Carbon storage by many terrestrial ecosystems can be limited by nutrients, predominantly nitrogen (N and phosphorus (P, in addition to other environmental constraints, water, light and temperature. However the spatial distribution and the extent of both N and P limitation at the global scale have not been quantified. Here we have developed a global model of carbon (C, nitrogen (N and phosphorus (P cycles for the terrestrial biosphere. Model estimates of steady state C and N pool sizes and major fluxes between plant, litter and soil pools, under present climate conditions, agree well with various independent estimates. The total amount of C in the terrestrial biosphere is 2767 Gt C, and the C fractions in plant, litter and soil organic matter are 19%, 4% and 77%. The total amount of N is 135 Gt N, with about 94% stored in the soil, 5% in the plant live biomass, and 1% in litter. We found that the estimates of total soil P and its partitioning into different pools in soil are quite sensitive to biochemical P mineralization. The total amount of P (plant biomass, litter and soil excluding occluded P in soil is 17 Gt P in the terrestrial biosphere, 33% of which is stored in the soil organic matter if biochemical P mineralization is modelled, or 31 Gt P with 67% in soil organic matter otherwise.

This model was used to derive the global distribution and uncertainty of N or P limitation on the productivity of terrestrial ecosystems at steady state under present conditions. Our model estimates that the net primary productivity of most tropical evergreen broadleaf forests and tropical savannahs is reduced by about 20% on average by P limitation, and most of the remaining biomes are N limited; N limitation is strongest in high latitude deciduous needle leaf forests, and reduces its net primary productivity by up to 40% under present conditions.

21 CFR 573.240 - Calcium periodate.

Science.gov (United States)

2010-04-01

... with calcium hydroxide or calcium oxide to form a substance consisting of not less than 60 percent by... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium periodate. 573.240 Section 573.240 Food... Additive Listing § 573.240 Calcium periodate. The food additive calcium periodate may be safely used in...

JAEA key facilities for global advanced fuel cycle R and D

Energy Technology Data Exchange (ETDEWEB)

Nomura, Shigeo; Yamamoto, Ryuichi [Nuclear Fuel Cycle Engineering Labos, JAEA, 4-33 Tokai-mura, Ibaraki, 319-1194 (Japan)

2008-07-01

Advanced fuel cycle will be realized with the mid and long term R and D during the long-term transition period from LWR cycle to advanced reactor fuel cycle. Most of JAEA facilities have been utilized to establish the current LWR and FBR (Fast Breeder Reactor) fuel cycle by implementing evolutionary R and D. An assessment of today's state experimental facilities concerning the following research issues: reprocessing, Mox fuel fabrication, irradiation and post-irradiation examination, waste management and nuclear data measurement, is made. The revolutionary R and D requests new issues to be studied: the TRU multi-recycling, minor actinide recycling, the assessment of proliferation resistance and the assessment of cost reduction. To implement the revolutionary R and D for advanced fuel cycle, however, these facilities should be refurbished to install new machines and process equipment to provide more flexible testing parameters.

Calcium chromate process related investigations

International Nuclear Information System (INIS)

Dillard, B.M.

1979-01-01

A pilot plant for production of calcium chromate has been scaled up to a small production facility at the General Electric Neutron Devices Department. In preparation for this scale-up, the process and final product were studied in order to evaluate problems not considered previously. The variables and processes studied included: (1) the determination of optimum drying temperature and time for product analysis; (2) the effect of the grade of lime used as the precipitating agent on the purity of the calcium chromate; (3) product purity when calcium chromate is precipitated by the addition of ammonium chromate to slaked lime; (4) the reagents best suited for cleaning calcium chromate spills; and (5) methods for determining hydroxide ion concentration in calcium chromate. The optimum drying time for the product before analysis is four hours at 600 0 C. Gases evolved at various temperatures during the drying process were carbon dioxide and water vapor. Technical grade lime produced calcium chromate of the highest purity. Both nitric and acetic acids were efficient dissolvers of calcium chromate spills. Direct titration of hydroxide ion with sulfuric acid gave an average recovery of 93% for samples spiked with calcium hydroxide. 1 figure, 17 tables

[The fasting calcium/creatinine ratio in patients with calcium stones and the relation with hypercalciuria and phosphocalcium metabolism].

Science.gov (United States)

Arrabal-Polo, Miguel Ángel; del Carmen Cano-García, María; Arrabal-Martín, Miguel

2016-04-01

To determine the importance of fasting calcium/creatinine ratio in patients with calcium stones and its relation with hypercalciuria and phospho-calcium metabolism. Cross-sectional study including 143 patients divided into two groups according to fasting calcium/creatinine. Group 1: 66 patients (calcium/ creatininecreatinine>0.11). A comparative study is performed between groups including phospho-calcium metabolism parameters and excretion of urinary lithogenic markers. Linear correlation studying calciuria and fasting calcium/ creatinine was performed. SPSS 17.0 statistical analysis software was used, considering p≤0.05. It is noteworthy that group 2 had increased 24 h urine calcium excretion in comparison to group 1 (229.3 vs 158.1; p=0.0001) and calcium/citrate (0.47 vs 0.34; p=0.001). There is a positive and significant correlation between calcium levels in 24 h urine and fasting calcium/creatinine (R=0.455; p=0.0001) and a cutoff is set at 0.127 (sensitivity 72%, specificity 66%) to determine hypercalciuria (>260 mg in 24 h). Increased fasting calcium/creatinine determines increased 24 hours calcium excretion, although the sensitivity and specificity to determine hypercalciuria is not high.

Globalization of the nuclear fuel cycle impact of developments on fuel management

Energy Technology Data Exchange (ETDEWEB)

Van Den Durpel, L.; Bertel, E. [OCDE-NEA, Nuclear Development Div., 92 - Issy-les-Moulineaux (France)

1999-07-01

Nuclear energy will have to cope more and more with a rapid changing environment due to economic competitive pressure and the de-regulatory progress. In current economic environment, utilities will have to focus strongly on the reduction of their total generation costs, covering the fuel cycle costs, which are only partly under their control. Developments in the fuel cycle will be in the short-term rather evolutionary addressing the current needs of utilities. However, within the context of sustainable development and more and more inclusion of externalities in energy generation costs, more performing developments in the fuel cycle could become important and feasible. A life-cycle design approach of the fuel cycle will be requested in order to cover all factors in order to decrease significantly the nuclear energy generation cost to compete with other alternative fuels in the long-term. This paper will report on some of the trends one could distinguish in the fuel cycle with emphasis on cost reduction. OECD/NEA is currently conducting a study on the fuel cycle aiming to assess current and future nuclear fuel cycles according the potential for further improvement of the full added-value chain of these cycles from a mainly technological and economical perspective including environmental and social considerations. (authors)

Life cycle analysis of distributed concentrating solar combined heat and power: economics, global warming potential and water

Science.gov (United States)

Norwood, Zack; Kammen, Daniel

2012-12-01

We report on life cycle assessment (LCA) of the economics, global warming potential and water (both for desalination and water use in operation) for a distributed concentrating solar combined heat and power (DCS-CHP) system. Detailed simulation of system performance across 1020 sites in the US combined with a sensible cost allocation scheme informs this LCA. We forecast a levelized cost of 0.25 kWh-1 electricity and 0.03 kWh-1 thermal, for a system with a life cycle global warming potential of ˜80 gCO2eq kWh-1 of electricity and ˜10 gCO2eq kWh-1 thermal, sited in Oakland, California. On the basis of the economics shown for air cooling, and the fact that any combined heat and power system reduces the need for cooling while at the same time boosting the overall solar efficiency of the system, DCS-CHP compares favorably to other electric power generation systems in terms of minimization of water use in the maintenance and operation of the plant. The outlook for water desalination coupled with distributed concentrating solar combined heat and power is less favorable. At a projected cost of 1.40 m-3, water desalination with DCS-CHP would be economical and practical only in areas where water is very scarce or moderately expensive, primarily available through the informal sector, and where contaminated or salt water is easily available as feed-water. It is also interesting to note that 0.40-1.90 m-3 is the range of water prices in the developed world, so DCS-CHP desalination systems could also be an economical solution there under some conditions.

Accounting for carbon cycle feedbacks in a comparison of the global warming effects of greenhouse gases

Energy Technology Data Exchange (ETDEWEB)

Gillett, Nathan P [Canadian Centre for Climate Modelling and Analysis, Environment Canada, University of Victoria, PO Box 1700, STN CSC, Victoria, BC, V8W 3V6 (Canada); Matthews, H Damon, E-mail: nathan.gillett@ec.gc.ca [Department of Geography, Planning and Environment, Concordia University, 1455 de Maisonneuve West, H 1255-26, Montreal, QC, H3G 1M8 (Canada)

2010-07-15

Greenhouse gases other than CO{sub 2} make a significant contribution to human-induced climate change, and multi-gas mitigation strategies are cheaper to implement than those which limit CO{sub 2} emissions alone. Most practical multi-gas mitigation strategies require metrics to relate the climate warming effects of CO{sub 2} and other greenhouse gases. Global warming potential (GWP), defined as the ratio of time-integrated radiative forcing of a particular gas to that of CO{sub 2} following a unit mass emission, is the metric used in the Kyoto Protocol, and we define mean global temperature change potential (MGTP) as an equivalent metric of the temperature response. Here we show that carbon-climate feedbacks inflate the GWPs and MGTPs of methane and nitrous oxide by {approx} 20% in coupled carbon-climate model simulations of the response to a pulse of 50 x 1990 emissions, due to a warming-induced release of CO{sub 2} from the land biosphere and ocean. The magnitude of this effect is expected to be dependent on the model, but it is not captured at all by the analytical models usually used to calculate metrics such as GWP. We argue that the omission of carbon cycle dynamics has led to a low bias of uncertain but potentially substantial magnitude in metrics of the global warming effect of other greenhouse gases, and we suggest that the carbon-climate feedback should be considered when greenhouse gas metrics are calculated and applied.

Accounting for carbon cycle feedbacks in a comparison of the global warming effects of greenhouse gases

International Nuclear Information System (INIS)

Gillett, Nathan P; Matthews, H Damon

2010-01-01

Greenhouse gases other than CO 2 make a significant contribution to human-induced climate change, and multi-gas mitigation strategies are cheaper to implement than those which limit CO 2 emissions alone. Most practical multi-gas mitigation strategies require metrics to relate the climate warming effects of CO 2 and other greenhouse gases. Global warming potential (GWP), defined as the ratio of time-integrated radiative forcing of a particular gas to that of CO 2 following a unit mass emission, is the metric used in the Kyoto Protocol, and we define mean global temperature change potential (MGTP) as an equivalent metric of the temperature response. Here we show that carbon-climate feedbacks inflate the GWPs and MGTPs of methane and nitrous oxide by ∼ 20% in coupled carbon-climate model simulations of the response to a pulse of 50 x 1990 emissions, due to a warming-induced release of CO 2 from the land biosphere and ocean. The magnitude of this effect is expected to be dependent on the model, but it is not captured at all by the analytical models usually used to calculate metrics such as GWP. We argue that the omission of carbon cycle dynamics has led to a low bias of uncertain but potentially substantial magnitude in metrics of the global warming effect of other greenhouse gases, and we suggest that the carbon-climate feedback should be considered when greenhouse gas metrics are calculated and applied.

Calcium regulation and Alzheimer’s disease

Directory of Open Access Journals (Sweden)

Deepthi Rapaka

2014-09-01

Full Text Available Activation of the neuron induces transient fluctuations in [Ca2+]i. This transient rise in [Ca2+]i is dependent on calcium entry via calcium channels and release of calcium from intracellular stores, finally resulting in increase in calcium levels, which activates calcium regulatory proteins to restore the resting calcium levels by binding to the calcium-binding proteins, sequestration into the endoplasmic reticulum and the mitochondria, and finally extrusion of calcium spike potential from the cell by adenosine triphosphate-driven Ca2+ pumps and the Na+/Ca2+ exchanger. Improper regulation of calcium signaling, sequentially, likely contributes to synaptic dysfunction and excitotoxic and/or apoptotic death of the vulnerable neuronal populations. The cognitive decline associated with normal aging is not only due to neuronal loss, but is fairly the result of synaptic connectivity. Many evidences support that Ca2+ dyshomeostasis is implicated in normal brain aging. Thus the chief factor associated with Alzheimer’s disease was found to be increase in the levels of free intracellular calcium, demonstrating that the excessive levels might lead to cell death, which provides a key target for the calcium channel blockers might be used as the neuroprotective agents in Alzheimer’s disease.

Effects of silica and calcium levels in nanobioglass ceramic particles on osteoblast proliferation

International Nuclear Information System (INIS)

Moorthi, A.; Parihar, P.R.; Saravanan, S.; Vairamani, M.; Selvamurugan, N.

2014-01-01

At nanoscale, bioglass ceramic (nBGC) particles containing calcium oxide (lime), silica and phosphorus pentoxide promote osteoblast proliferation. However, the role of varied amounts of calcium and silica present in nBGC particles on osteoblast proliferation is not yet completely known. Hence, the current work was aimed at synthesizing two different nBGC particles with varied amounts of calcium oxide and silica, nBGC-1: SiO 2 :CaO:P 2 O 5 ; mol% ∼ 70:25:5 and nBGC-2: SiO 2 :CaO:P 2 O 5 ; mol% ∼ 64:31:5, and investigating their role on osteoblast proliferation. The synthesized nBGC particles were characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) studies. They exhibited their size at nanoscale and were non-toxic to human osteoblastic cells (MG-63). The nBGC-2 particles were found to have more effect on stimulation of osteoblast proliferation and promoted entering of more cells into G2/M cell cycle phase compared to nBGC-1 particles. There was a differential expression of cyclin proteins in MG-63 cells by nBGC-1 and nBGC-2 treatments, and the expression of cyclin B1 and E proteins was found to be more by nBGC-2 treatment. Thus, these results provide us a new insight in understanding the design of various nBGC particles by altering their ionic constituents with desirable biological properties thereby supporting bone augmentation. - Highlights: • nBGC particles with varied amounts of calcium and silica were synthesized. • They were non-toxic to human osteoblastic cells. • nBGC-2 particles had more effect on stimulation of osteoblast proliferation. • nBGC-2 particles promoted entering of osteoblasts into G2/M cell cycle phase. • Expression of cyclin B1 and E proteins was found to be more by nBGC-2 treatment

Effects of silica and calcium levels in nanobioglass ceramic particles on osteoblast proliferation

Energy Technology Data Exchange (ETDEWEB)

Moorthi, A.; Parihar, P.R.; Saravanan, S.; Vairamani, M.; Selvamurugan, N., E-mail: selvamurugan.n@ktr.srmuniv.ac.in

2014-10-01

At nanoscale, bioglass ceramic (nBGC) particles containing calcium oxide (lime), silica and phosphorus pentoxide promote osteoblast proliferation. However, the role of varied amounts of calcium and silica present in nBGC particles on osteoblast proliferation is not yet completely known. Hence, the current work was aimed at synthesizing two different nBGC particles with varied amounts of calcium oxide and silica, nBGC-1: SiO{sub 2}:CaO:P{sub 2}O{sub 5}; mol% ∼ 70:25:5 and nBGC-2: SiO{sub 2}:CaO:P{sub 2}O{sub 5}; mol% ∼ 64:31:5, and investigating their role on osteoblast proliferation. The synthesized nBGC particles were characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) studies. They exhibited their size at nanoscale and were non-toxic to human osteoblastic cells (MG-63). The nBGC-2 particles were found to have more effect on stimulation of osteoblast proliferation and promoted entering of more cells into G2/M cell cycle phase compared to nBGC-1 particles. There was a differential expression of cyclin proteins in MG-63 cells by nBGC-1 and nBGC-2 treatments, and the expression of cyclin B1 and E proteins was found to be more by nBGC-2 treatment. Thus, these results provide us a new insight in understanding the design of various nBGC particles by altering their ionic constituents with desirable biological properties thereby supporting bone augmentation. - Highlights: • nBGC particles with varied amounts of calcium and silica were synthesized. • They were non-toxic to human osteoblastic cells. • nBGC-2 particles had more effect on stimulation of osteoblast proliferation. • nBGC-2 particles promoted entering of osteoblasts into G2/M cell cycle phase. • Expression of cyclin B1 and E proteins was found to be more by nBGC-2 treatment.

Protein-induced satiation and the calcium-sensing receptor

Directory of Open Access Journals (Sweden)

Ojha U

2018-03-01

Full Text Available Utkarsh Ojha Faculty of Medicine, Imperial College School of Medicine, Imperial College London, London, UK Abstract: Obesity is a major global health issue. High-protein diets have been shown to be associated with weight loss and satiety. The precise mechanism by which protein-rich diets promote weight loss remains unclear. Evidence suggests amino acids, formed as a consequence of protein digestion, are sensed by specific receptors on L-cells in the gastrointestinal (GI tract. These L-cells respond by secreting gut hormones that subsequently induce satiety. In recent years, the calcium-sensing receptor has been identified in several cells of the GI tract, including L-cells, and suggested to sense specific amino acids. This review evaluates the evidence for protein-rich diets in inducing weight loss and how the calcium-sensing receptor may be implicated in this phenomenon. Commandeering the mechanisms by which elements of a protein-rich diet suppress appetite may provide another successful avenue for developing anti-obesity drugs. Keywords: amino acids, energy regulation, obesity therapy, glucagon-like-peptide-1, peptide YY

21 CFR 184.1207 - Calcium lactate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium lactate. 184.1207 Section 184.1207 Food and... Substances Affirmed as GRAS § 184.1207 Calcium lactate. (a) Calcium lactate (C6H10CaO6.xH2O, where x is any... calcium carbonate or calcium hydroxide. (b) The ingredient meets the specifications of the Food Chemicals...

CaO insulator coatings on a vanadium-base alloy in liquid 2 at.% calcium-lithium

International Nuclear Information System (INIS)

Park, J.H.; Kassner, T.F.

1996-01-01

The electrical resistance of CaO coatings produced on V-4%Cr-4%Ti and V-15%Cr-5%Ti by exposure of the alloy (round bottom samples 6-in. long by 0.25-in. dia.) to liquid lithium that contained 2 at.% dissolved calcium was measured as a function of time at temperatures between 300-464 degrees C. The solute element, calcium in liquid lithium, reacted with the alloy substrate at these temperatures for 17 h to produce a calcium coating ∼7-8 μm thick. The calcium-coated vanadium alloy was oxidized to form a CaO coating. Resistance of the coating layer on V-15Cr-5Ti, measured in-situ in liquid lithium that contained 2 at.% calcium, was 1.0 x 10 10 Ω-cm 2 at 300 degrees C and 400 h, and 0.9 x 10 10 Ω-cm 2 at 464 degrees C and 300 h. Thermal cycling between 300 and 464 degrees C changed the resistance of the coating layer, which followed insulator behavior. Examination of the specimen after cooling to room temperature revealed no cracks in the CaO coating. The coatings were evaluated by optical microscopy, scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), and X-ray analysis. Adhesion between CaO and vanadium alloys was enhanced as exposure time increased

Calcium Occupancy of N-terminal Sites within Calmodulin Induces Inhibition of the Ryanodine Receptor Calcium Release Channel

Energy Technology Data Exchange (ETDEWEB)

Boschek, Curt B; Jones, Terry E; Squier, Thomas C; Bigelow, Diana J

2007-08-01

Calmodulin (CaM) regulates calcium release from intracellular stores in skeletal muscle through its association with the ryanodine receptor (RyR1) calcium release channel, where CaM association enhances channel opening at resting calcium levels and its closing at micromolar calcium levels associated with muscle contraction. A high-affinity CaM-binding sequence (RyRp) has been identified in RyR1, which corresponds to a 30-residue sequence (i.e., K3614 – N3643) located within the central portion of the primary sequence. However, it is currently unclear whether the identified CaM-binding sequence a) senses calcium over the physiological range of calcium-concentrations associated with RyR1 regulation or b) plays a structural role unrelated to the calcium-dependent modulation of RyR1 function. Therefore, we have measured the calcium-dependent activation of the individual domains of CaM in association with RyRp and their relationship to the CaM-dependent regulation of RyR1. These measurements utilize an engineered CaM, permitting the site-specific incorporation of N-(1-pyrene) maleimide at either T34C (PyN-CaM) or T110C (PyC-CaM) in the N- and C-domains, respectively. Consistent with prior measurements, we observe a high-affinity association between both apo- and calcium-activated CaM and RyRp. Upon association with RyRp, fluorescence changes in PyN-CaM or PyC-CaM permit the measurement of the calcium-activation of these individual domains. Fluorescence changes upon calcium-activation of PyC-CaM in association with RyRp are indicative of high-affinity calcium-dependent activation of the C-terminal domain of CaM bound to RyRp at resting calcium levels and the activation of the N-terminal domain at levels of calcium associated cellular activation. In comparison, occupancy of calcium-binding sites in the N-domain of CaM mirrors the calcium-dependence of RyR1 inhibition observed at activating calcium levels, where [Ca]1/2 = 4.3 0.4 μM, suggesting a direct regulation of Ry

Convergence of soil nitrogen isotopes across global climate gradients

Science.gov (United States)

Craine, Joseph M.; Elmore, Andrew J.; Wang, Lixin; Augusto, Laurent; Baisden, W. Troy; Brookshire, E. N. J.; Cramer, Michael D.; Hasselquist, Niles J.; Hobbie, Erik A.; Kahmen, Ansgar; Koba, Keisuke; Kranabetter, J. Marty; Mack, Michelle C.; Marin-Spiotta, Erika; Mayor, Jordan R.; McLauchlan, Kendra K.; Michelsen, Anders; Nardoto, Gabriela B.; Oliveira, Rafael S.; Perakis, Steven S.; Peri, Pablo L.; Quesada, Carlos A.; Richter, Andreas; Schipper, Louis A.; Stevenson, Bryan A.; Turner, Benjamin L.; Viani, Ricardo A. G.; Wanek, Wolfgang; Zeller, Bernd

2015-01-01

Quantifying global patterns of terrestrial nitrogen (N) cycling is central to predicting future patterns of primary productivity, carbon sequestration, nutrient fluxes to aquatic systems, and climate forcing. With limited direct measures of soil N cycling at the global scale, syntheses of the 15 N: 14 N ratio of soil organic matter across climate gradients provide key insights into understanding global patterns of N cycling. In synthesizing data from over 6000 soil samples, we show strong global relationships among soil N isotopes, mean annual temperature (MAT), mean annual precipitation (MAP), and the concentrations of organic carbon and clay in soil. In both hot ecosystems and dry ecosystems, soil organic matter was more enriched in 15 N than in corresponding cold ecosystems or wet ecosystems. Below a MAT of 9.8°C, soil δ15N was invariant with MAT. At the global scale, soil organic C concentrations also declined with increasing MAT and decreasing MAP. After standardizing for variation among mineral soils in soil C and clay concentrations, soil δ15N showed no consistent trends across global climate and latitudinal gradients. Our analyses could place new constraints on interpretations of patterns of ecosystem N cycling and global budgets of gaseous N loss.

The Evolution of Global Politics

Directory of Open Access Journals (Sweden)

George Moldeski

1995-08-01

Full Text Available The rise and decline of world powers has attracted much scholarly attention in recent years. The theory of long cycles answers parsimoniously the question: why, in the past half millenium, have Portugal, the Dutch Republic, Britain (twice, and the United States risen to global leadership while others have failed to do so? This accounts for the success, or failure, of individual states, but to explain the entire sequence we need to employ an evolutionary paradigm that proposes that each of these long cycles is one mechanism in a spectrum of global evolutionary processes. The leadership succession is an intermediate stage in the evolution og global politics, whose next likely major phase, reaching a high point later in the 21st century, will be the gradual absorption of the informal role of global leadership, when embedded in a democratic community, into a network of more formal positions within an emerging global organization of a federalist character. The conditions of that process can now be specified.

Acidosis and Urinary Calcium Excretion

DEFF Research Database (Denmark)

Alexander, R Todd; Cordat, Emmanuelle; Chambrey, Régine

2016-01-01

Metabolic acidosis is associated with increased urinary calcium excretion and related sequelae, including nephrocalcinosis and nephrolithiasis. The increased urinary calcium excretion induced by metabolic acidosis predominantly results from increased mobilization of calcium out of bone and inhibi...

The role of calcium utilization of intestinal flora on urinary calcium excretion

International Nuclear Information System (INIS)

Yurt Lambrecht, F.; Uenak, P.; Kavukcu, S.; Soylu, A.; Tuerkmen, M.; Kasap, B.; Yucesoy, M.; Esen, N.

2005-01-01

Aim: To investigate whether calcium utilization of intestinal flora has any effect on urinary calcium excretion, like oxalate degrading effect of Oxalobacter formigenes. Materials and Methods: The data of urinary calcium excretion examinations were evaluated. 0.1 g/ml of feces samples were implanted in broths. 5 μL of 45 Ca solution was added to the samples and they were incubated for 24 hours at 37 degree C. The amount of bacteriae in the samples was determined as colony forming unit (CFU). 200 μL of the samples were filtrated by 0.45 μm membrane and rinsed by 200 μL pure water. 45 Ca activity ( 45 Ca) of bacteria in the membrane was counted by GM detector for 100 seconds. Then, activity per CFU ( 45 Ca/CFU) was calculated and compared in hypercalciuric (calciuria >4; mg/kg/hour and/or calcium/creatinine ratio>0.21; Group I) and normocalciuric (Group II) patients. Results: Samples of 29 patients with a mean age of 7.50±4.28 (1.5-16) years were evaluated. 11 of them were female (M/F: 18/11). There were 14 patients in Group I and 15 patients in Group II, 45 Ca/CFU was not different for neither aerobic nor anaerobic bacteries between the two groups (p:0.983, p:0.601, respectively). 24-hour urine calcium levels were negatively but not significantly correlated to aerobic and anaerobic 45 Ca/CFU (p:0.079, r:-0.145; p:0.260, r:-0.420, respectively) in hypercalciuric patients. Besides, in normocalciuric patients, 24-hour urine calcium levels were correlated positively to aerobic and negatively to anaerobic 45 Ca/CFU again in an insignificant manner (p:0.509, r: 0.223; p:0623, r:-0.257, respectively). Conclusion: In this, study, similar 45 Ca/CFU levels in both hypercalciuric and normocalciuric patients imply that calcium utilization of intestinal flora does not have a distinct effect on urinary calcium excretion but, although not significant, there was a negative correlation between urine calcium levels and bacterial 45 Ca/CFU levels especially in hypercalciuric

Derivation of a northern-hemispheric biomass map for use in global carbon cycle models

Science.gov (United States)

Thurner, Martin; Beer, Christian; Santoro, Maurizio; Carvalhais, Nuno; Wutzler, Thomas; Schepaschenko, Dmitry; Shvidenko, Anatoly; Kompter, Elisabeth; Levick, Shaun; Schmullius, Christiane

2013-04-01

Quantifying the state and the change of the World's forests is crucial because of their ecological, social and economic value. Concerning their ecological importance, forests provide important feedbacks on the global carbon, energy and water cycles. In addition to their influence on albedo and evapotranspiration, they have the potential to sequester atmospheric carbon dioxide and thus to mitigate global warming. The current state and inter-annual variability of forest carbon stocks remain relatively unexplored, but remote sensing can serve to overcome this shortcoming. While for the tropics wall-to-wall estimates of above-ground biomass have been recently published, up to now there was a lack of similar products covering boreal and temperate forests. Recently, estimates of forest growing stock volume (GSV) were derived from ENVISAT ASAR C-band data for latitudes above 30° N. Utilizing a wood density and a biomass compartment database, a forest carbon density map covering North-America, Europe and Asia with 0.01° resolution could be derived out of this dataset. Allometric functions between stem, branches, root and foliage biomass were fitted and applied for different leaf types (broadleaf, needleleaf deciduous, needleleaf evergreen forest). Additionally, this method enabled uncertainty estimation of the resulting carbon density map. Intercomparisons with inventory-based biomass products in Russia, Europe and the USA proved the high accuracy of this approach at a regional scale (r2 = 0.70 - 0.90). Based on the final biomass map, the forest carbon stocks and densities (excluding understorey vegetation) for three biomes were estimated across three continents. While 40.7 ± 15.7 Gt of carbon were found to be stored in boreal forests, temperate broadleaf/mixed forests and temperate conifer forests contain 24.5 ± 9.4 Gt(C) and 14.5 ± 4.8 Gt(C), respectively. In terms of carbon density, most of the carbon per area is stored in temperate conifer (62.1 ± 20.7 Mg

In vitro assessments of experimental NaF dentifrices containing a prospective calcium phosphate technology.

Science.gov (United States)

Karlinsey, Robert L; Mackey, Allen C; Stookey, George K; Pfarrer, Aaron M

2009-06-01

To determine the fluoride dose response of experimental NaF dentifrices containing a prospective calcium phosphate technology, along with the corresponding relative enamel and dentin abrasion values. 3 mm diameter bovine enamel specimens were mounted, ground and polished, and softened in a carbopol-lactic acid solution (pH = 5.0) for 36 hours at 37 degrees C. Specimens were then measured for baseline Vickers microhardness and stratified (N = 18, mean VHN = 33) into eight groups. These groups consisted of a placebo paste, four test dentifrices (A, B, C, D) with three of the four (A, B, C) containing a promising calcium phosphate ingredient, Crest Cavity Protection, MI Paste Plus, and PreviDent Booster 5000. The groups were cycled in a lesion reversal pH cycling model consisting of four 2-minute treatment periods (diluted 1:3 with DI water) and one 4-hour acid challenge (carbopol-lactic acid, pH = 5.0) per day. Between these events, specimens were immersed in artificial saliva (pH = 7.0). After 20 days of cycling, the specimens were microdrilled and analyzed for fluoride content, and also measured for Vickers surface microhardness after 10 and 20 days of cycling and after a 2-hour and 16-hour post-cycle acid challenge (carbopol-lactic acid, pH = 5.0). Separately, relative dentin and enamel abrasion (RDA and REA) were performed using the ADA recommended radiotracer method. A fluoride dose response was observed for the test dentifrices after 10 and 20 days of pH cycling, with test dentifrice C promoting the highest remineralization among the groups while both the MI Paste Plus and PreviDent systems provide the least remineralization (one-way ANOVA, SNK, P dentin (one-way ANOVA, SNK, P < 0.05). Altogether, these data show the developmental test dentifrices demonstrate a fluoride dose response and show great promise in remineralizing white-spot enamel lesions relative to MI Paste Plus and PreviDent.

Energy basis of disasters and the cycles of order and disorder

International Nuclear Information System (INIS)

Alexander, J.F. Jr.

1978-01-01

A quantitative theory of cycles order and disorder was applied to the earth and evaluated to form an energy basis for the global cycles, surges, and disasters. Energy circuit language was used to diagram the world system and show a common pattern in the order--disorder processes. Storms, floods, forest fires, volcanic eruptions, earthquakes, urban fires, and wars were modeled as the catastrophic release of energy previously converged and stored. Released energy disordered and recycled material available to stimulate a new cycle of growth. Cascading of catastrophic processes of disasters was modeled with a world web. The feedback in the global energy web was provided by the control action of disaster pulses. The global model was presented in both diagrammatic and differential equation form with the energy flows and storages evaluated. Order--disorder models of the atmospheric, oceanic, biological, geological, and urban systems of earth were connected to form an energy convergence network. The global energy model was used to calculate energy quality factors (ratio of energy of one type generating energy of another type) for the earth's major energy transformations. The theory provided suggestions for land-use policy. Energy ratios that provide a quantitative basis for disaster planning can be developed for a local environment of pulsing energy. Possibilities were considered that cycles of order and disorder of the earth are synchronized by cycles of sunspots. Energy quality and pulse amplifier ratios of solar flares may be high enough to control many global cycles

Calcium binding properties of calcium dependent protein kinase 1 (CaCDPK1) from Cicer arietinum.

Science.gov (United States)

Dixit, Ajay Kumar; Jayabaskaran, Chelliah

2015-05-01

Calcium plays a crucial role as a secondary messenger in all aspects of plant growth, development and survival. Calcium dependent protein kinases (CDPKs) are the major calcium decoders, which couple the changes in calcium level to an appropriate physiological response. The mechanism by which calcium regulates CDPK protein is not well understood. In this study, we investigated the interactions of Ca(2+) ions with the CDPK1 isoform of Cicer arietinum (CaCDPK1) using a combination of biophysical tools. CaCDPK1 has four different EF hands as predicted by protein sequence analysis. The fluorescence emission spectrum of CaCDPK1 showed quenching with a 5 nm red shift upon addition of calcium, indicating conformational changes in the tertiary structure. The plot of changes in intensity against calcium concentrations showed a biphasic curve with binding constants of 1.29 μM and 120 μM indicating two kinds of binding sites. Isothermal calorimetric (ITC) titration with CaCl2 also showed a biphasic curve with two binding constants of 0.027 μM and 1.7 μM. Circular dichroism (CD) spectra showed two prominent peaks at 208 and 222 nm indicating that CaCDPK1 is a α-helical rich protein. Calcium binding further increased the α-helical content of CaCDPK1 from 75 to 81%. Addition of calcium to CaCDPK1 also increased fluorescence of 8-anilinonaphthalene-1-sulfonic acid (ANS) indicating exposure of hydrophobic surfaces. Thus, on the whole this study provides evidence for calcium induced conformational changes, exposure of hydrophobic surfaces and heterogeneity of EF hands in CaCDPK1. Copyright © 2015 Elsevier GmbH. All rights reserved.

Association between cadmium and calcium uptake and distribution during the moult cycle of female shore crabs, Carcinus maenas: an in vivo study

International Nuclear Information System (INIS)

Bondgaard, Morten; Bjerregaard, Poul

2005-01-01

Net influxes into the haemolymph and tissue distribution of 45 Ca and 109 Cd were studied in vivo in female Carcinus maenas at different moult stages. Net influxes of 45 Ca and 109 Cd from water were higher in postmoult (A and B) C. maenas than in C 3 - and C 4 -intermoult crabs and the net influx of calcium was higher in C 3 -intermoult crabs than in C 4 -intermoult crabs. The net influxes of 45 Ca and 109 Cd increased in postmoult C. maenas with decreasing external calcium concentrations at constant salinity. At all external calcium concentrations a significant correlation existed between 45 Ca and 109 Cd accumulated in the haemolymph of individual animals. In vivo exposure of postmoult C. maenas to external lanthanum decreased the 45 Ca and 109 Cd uptake rates to 30 and 10%, respectively, of the control values. About 30% of injected 109 Cd were found in the midgut gland, 10-20% in the gills and only a few (1-2) percent was lost to the seawater 24 h after injection. No major variations in tissue distribution of 109 Cd were observed between moult stages in these tissues. Premoult crabs retained more cadmium in the haemolymph 24 h after injection than other moult stages, and postmoult crabs retained more in muscle. Between 20 and 40% of the injected 45 Ca were excreted to the water, while only a few percent of the injected 45 Ca were found in the soft tissues 24 h after injection. Large moult stage variations, however, were observed in the tissue distribution of internalised 45 Ca. This study demonstrates that cadmium and calcium uptakes are elevated in postmoult C. maenas. The results indicate that cadmium and calcium in this stage are taken up via Ca 2+ -channels located in the apical membrane of gill epithelium cells. When internalised, however, cadmium and calcium are metabolised in fundamentally different ways, determined by the chemical properties and biological significance of the two metals

Calcium transport in turtle bladder

International Nuclear Information System (INIS)

Sabatini, S.; Kurtzman, N.A.

1987-01-01

Unidirectional 45 Ca fluxes were measured in the turtle bladder under open-circuit and short-circuit conditions. In the open-circuited state net calcium flux (J net Ca ) was secretory (serosa to mucosa). Ouabain reversed J net Ca to an absorptive flux. Amiloride reduced both fluxes such that J net Ca was not significantly different from zero. Removal of mucosal sodium caused net calcium absorption; removal of serosal sodium caused calcium secretion. When bladders were short circuited, J net Ca decreased to approximately one-third of control value but remained secretory. When ouabain was added under short-circuit conditions, J net Ca was similar in magnitude and direction to ouabain under open-circuited conditions (i.e., absorptive). Tissue 45 Ca content was ≅30-fold lower when the isotope was placed in the mucosal bath, suggesting that the apical membrane is the resistance barrier to calcium transport. The results obtained in this study are best explained by postulating a Ca 2+ -ATPase on the serosa of the turtle bladder epithelium and a sodium-calcium antiporter on the mucosa. In this model, the energy for calcium movement would be supplied, in large part, by the Na + -K + -ATPase. By increasing cell sodium, ouabain would decrease the activity of the mucosal sodium-calcium exchanger (or reverse it), uncovering active calcium transport across the serosa

Calcium in Urine Test

Science.gov (United States)

... K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2 nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Calcium, Serum; Calcium and Phosphates, Urine; ...

Understanding spatial and temporal patterning of astrocyte calcium transients via interactions between network transport and extracellular diffusion

Science.gov (United States)

Shtrahman, E.; Maruyama, D.; Olariu, E.; Fink, C. G.; Zochowski, M.

2017-02-01

Astrocytes form interconnected networks in the brain and communicate via calcium signaling. We investigate how modes of coupling between astrocytes influence the spatio-temporal patterns of calcium signaling within astrocyte networks and specifically how these network interactions promote coordination within this group of cells. To investigate these complex phenomena, we study reduced cultured networks of astrocytes and neurons. We image the spatial temporal patterns of astrocyte calcium activity and quantify how perturbing the coupling between astrocytes influences astrocyte activity patterns. To gain insight into the pattern formation observed in these cultured networks, we compare the experimentally observed calcium activity patterns to the patterns produced by a reduced computational model, where we represent astrocytes as simple units that integrate input through two mechanisms: gap junction coupling (network transport) and chemical release (extracellular diffusion). We examine the activity patterns in the simulated astrocyte network and their dependence upon these two coupling mechanisms. We find that gap junctions and extracellular chemical release interact in astrocyte networks to modulate the spatiotemporal patterns of their calcium dynamics. We show agreement between the computational and experimental findings, which suggests that the complex global patterns can be understood as a result of simple local coupling mechanisms.

Atmospheric Carbon Dioxide and the Global Carbon Cycle: The Key Uncertainties

Science.gov (United States)

Peng, T. H.; Post, W. M.; DeAngelis, D. L.; Dale, V. H.; Farrell, M. P.

1987-12-01

The biogeochemical cycling of carbon between its sources and sinks determines the rate of increase in atmospheric CO{sub 2} concentrations. The observed increase in atmospheric CO{sub 2} content is less than the estimated release from fossil fuel consumption and deforestation. This discrepancy can be explained by interactions between the atmosphere and other global carbon reservoirs such as the oceans, and the terrestrial biosphere including soils. Undoubtedly, the oceans have been the most important sinks for CO{sub 2} produced by man. But, the physical, chemical, and biological processes of oceans are complex and, therefore, credible estimates of CO{sub 2} uptake can probably only come from mathematical models. Unfortunately, one- and two-dimensional ocean models do not allow for enough CO{sub 2} uptake to accurately account for known releases. Thus, they produce higher concentrations of atmospheric CO{sub 2} than was historically the case. More complex three-dimensional models, while currently being developed, may make better use of existing tracer data than do one- and two-dimensional models and will also incorporate climate feedback effects to provide a more realistic view of ocean dynamics and CO{sub 2} fluxes. The instability of current models to estimate accurately oceanic uptake of CO{sub 2} creates one of the key uncertainties in predictions of atmospheric CO{sub 2} increases and climate responses over the next 100 to 200 years.

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