Use of 14C/C Ratios to Provide Insights into the Magnitude of Carbon Turnover in the Crustose Saxicolous Lichen Caloplaca Trachyphylla

2002 ◽  
Vol 34 (2) ◽  
pp. 169-179 ◽  
Author(s):  
G. Bench ◽  
B. M. Clark ◽  
N. F. Mangelson ◽  
L. L. St. Clair ◽  
L. B. Rees ◽  
...  
Keyword(s):  
Growth Rates ◽  
Radial Growth ◽  
Total Carbon ◽  
Simple Explanation ◽  
Carbon Turnover ◽  
Fixed Carbon ◽  
The Past ◽  
Annual Carbon ◽  
Insight Into ◽  
Lichen Growth

Abstract14C/C ratios in samples from radial transects across individual thalli of Caloplaca trachyphylla collected at two sites were measured and the results used to investigate whether 14C/C data might provide some insight into the magnitude of carbon turnover in this lichen species. The 14C/C data suggest that significant internal recycling/translocation of carbon is unlikely in the sampled thalli. However, converting the 14C/C data for the larger intact thalli sampled at each site to calendar years, using the atmospheric ⊃14C record, does not yield constant or even monotonically varying growth rates. Since crustose lichen growth rates are constant or decrease with thallus size, and since the 14C/C data from these larger thalli show a relatively small spread in 14C/C data values compared to the Northern Hemisphere atmospheric ⊃14C record over the past 50 years, the 14C/C data suggest that carbon turnover may be occurring. Carbon turnover was modelled starting with the atmospheric ⊃14C record. Turnover was incorporated so that for each year in the record a constant percentage of the total carbon was lost annually and replaced by new photosynthetically fixed carbon with a 14C/C ratio equal to that of the contemporary atmosphere. The 14C/C data from the radial samples were then converted to a calendar year using the model record. Constant annual carbon turnover values of 0, 0·5, 1, 1·5, 2, 2·5, 3, 3·5, 4, 4·5, 5, 5·5, 6, 7, 8, 9, 10, 15, 20, 25 and 50% were modelled. Carbon turnover values between 3 and 6% created ⊃14C model records that when applied to 14C/C data from the thalli produced constant radial growth rates that were: (1) identical for all lichens at a given site, and (2) independent of lichen size at a given site. The 14C/C data further indicate that annual carbon turnover in this species of lichen is <10%, independent of the nature of thallus radial growth. The data and modelling suggest that carbon turnover might provide a simple explanation for the 14C/C data from the thalli and might explain the discrepancies between the standard atmospheric ⊃14C record and the 14C/C ratios observed in C. trachyphylla.

Sizes and Growth-Rates of Thalli of the Lichen Rhizocarpon Geographicum on the Moraines of the Glacier De Valsorey, Valais, Switzerland

1983 ◽  
Vol 15 (3) ◽  
pp. 249-261 ◽  
Author(s):  
M. C. F. Proctor
Keyword(s):  
Growth Rates ◽  
Radial Growth ◽  
Growth Curves ◽  
Field Measurements ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Rhizocarpon Geographicum ◽  
Constant Rate ◽  
Maximum Parameters ◽  
Lichen Growth

AbstractMeasurements of thalli of Rhizocarpon geographicum on the recent moraines of the Glacier de Valsorey and their surroundings are considered in relation to thallus growth rates and colonization following glacial recession. Photographs taken in 1975 and 1979 show that up to c. 3.5 cm diam the relation of maximum growth-rate to thallus size is approximated by a growth curve of the kind derived by Aplin and Hill, rising asymptotically towards a constant rate of radial growth (here c. 0.5 mm year−1). Growth-rates of many individual thalli fall well below the maximum. Parameters of the fitted growth curves are used to construct curves of thallus radius against time. Taken in conjunction with the field measurements these suggest two main phases of colonization, one from about 1880 to 1910, and one from about 1930 onwards. Some general considerations relating to lichenometry and lichen growth curves are discussed.

Lichenometric dating using Rhizocarpon subgenus Rhizocarpon in the Patagonian Andes, Argentina

2009 ◽  
Vol 71 (3) ◽  
pp. 271-283 ◽  
Author(s):  
Irene Adriana Garibotti ◽  
Ricardo Villalba
Keyword(s):  
Tree Ring ◽  
Growth Rates ◽  
Growth Curves ◽  
The Past ◽  
Glacier Fluctuations ◽  
Andean Cordillera ◽  
Latitudinal Difference ◽  
Patagonian Andes ◽  
Over Time ◽  
Lichen Growth

AbstractThis study represents the first attempt to develop and apply lichenometric dating curves of Rhizocarpon subgenus Rhizocarpon for dating glacier fluctuations in the Patagonian Andes. Six glaciers were studied along the Patagonian Andes. Surfaces of known ages (historical evidences and tree-ring analyses) were used as control sites to develop indirect lichenometric dating curves. Dating curves developed for the studied glaciers show the same general logarithmic form, indicating that growth rate of subgenus Rhizocarpon decreases over time. The strong west–east precipitation gradient across the Andean Cordillera introduces statistically significant differences in the growth curves, with faster growth rates in the moist west sites than the drier eastern sites. Latitudinal difference among the studied glaciers does not appear to be a major factor regulating lichen growth rates. Therefore, we developed two lichenometric curves for dating glacier fluctuations in wetter and drier sites in the Patagonian Andes during the past 450 yrs. Application of the developed curves to moraine dating allowed us to complement glacial chronologies previously obtained by tree-ring analyses. A first chronosequence for moraine formation in the Torrecillas Glacier (42°S) is presented. Our findings confirm the utility of lichenometry to date deglaciated surfaces in the Patagonian Andes.

scholarly journals Quality-quantity tradeoffs drive functional trait evolution in a model microalgal “climate change winner”

2019 ◽  
Author(s):  
Rasmus T. Lindberg ◽  
Sinéad Collins
Keyword(s):  
Climate Change ◽  
Population Growth ◽  
Functional Traits ◽  
Growth Rates ◽  
Functional Trait ◽  
Fixed Carbon ◽  
Short Term ◽  
Population Growth Rates ◽  
Environmental Amelioration ◽  
Insight Into

AbstractPhytoplankton are the unicellular photosynthetic microbes that form the base of aquatic ecosystems, and their responses to global change will impact everything from food web dynamics to global nutrient cycles. Some taxa respond to environmental change by increasing population growth rates in the short-term, and, based on this, are projected to increase in frequency over decades. To gain insight into how functional traits in these projected “climate change winners” change over different timescales, we evolved populations of microalgae in ameliorated environments for several hundred generations. While populations initially responded to environmental amelioration by increasing photosynthesis and population growth rates as expected, this response was not sustained. Instead, most populations evolved to allocate a smaller proportion of carbon to growth while increasing their ability to tolerate and metabolise reactive oxygen species (ROS). This diversion of fixed carbon from growth to catabolism underlies a quality-quantity tradeoff in daughter cell production which drives the evolution of population growth rates and of functional traits that underlie the ecological and biogeochemical roles of phytoplankton. There is intraspecific variation in the trait combinations that evolve, but all are consistent with mitigating ROS production and accumulation in ameliorated environments over hundreds of generations. This offers both an evolutionary and a metabolic framework for understanding how functional traits can change in primary producers projected to be “climate change winners”, and suggests that short-term population booms and associated trait shifts have the potential to be dampened or reversed if environmental amelioration persists.

Recovery boiler sootblowers: History and technological advances

TAPPI Journal ◽  
2015 ◽  
Vol 14 (1) ◽  
pp. 51-60
Author(s):  
HONGHI TRAN ◽  
DANNY TANDRA
Keyword(s):  
Cfd Modeling ◽  
Computing Systems ◽  
The Past ◽  
Technological Advances ◽  
Recovery Boilers ◽  
Computational Fluid Dynamics Cfd ◽  
Recovery Boiler ◽  
Steam Parameters ◽  
Insight Into ◽  
Deposit Removal

Sootblowing technology used in recovery boilers originated from that used in coal-fired boilers. It started with manual cleaning with hand lancing and hand blowing, and evolved slowly into online sootblowing using retractable sootblowers. Since 1991, intensive research and development has focused on sootblowing jet fundamentals and deposit removal in recovery boilers. The results have provided much insight into sootblower jet hydrodynamics, how a sootblower jet interacts with tubes and deposits, and factors influencing its deposit removal efficiency, and have led to two important innovations: fully-expanded sootblower nozzles that are used in virtually all recovery boilers today, and the low pressure sootblowing technology that has been implemented in several new recovery boilers. The availability of powerful computing systems, superfast microprocessors and data acquisition systems, and versatile computational fluid dynamics (CFD) modeling capability in the past two decades has also contributed greatly to the advancement of sootblowing technology. High quality infrared inspection cameras have enabled mills to inspect the deposit buildup conditions in the boiler during operation, and helped identify problems with sootblower lance swinging and superheater platens and boiler bank tube vibrations. As the recovery boiler firing capacity and steam parameters have increased markedly in recent years, sootblowers have become larger and longer, and this can present a challenge in terms of both sootblower design and operation.

Accelerating Agricultural Growth—Is Irrigation Institutional Reform Necessary? (Distinguishedl Lecture)

1996 ◽  
Vol 35 (4I) ◽  
pp. 399-417 ◽  
Author(s):  
John W. Mellor
Keyword(s):  
Growth Rates ◽  
Irrigation System ◽  
Institutional Reform ◽  
Residual Effect ◽  
Agricultural Growth ◽  
The Past ◽  
Major Reform ◽  
History Of ◽  
The Right ◽  
Economic Growth Rates

The right to the flow of income from water is vigorously pursued, protected, and fought over in any arid part of the world. Pakistan is of course no exception. Reform of irrigation institutions necessarily changes the rights to water, whether it be those of farmers, government, or government functionaries. Those perceived rights may be explicit and broadly accepted, or simply takings that are not even considered legitimate. Nevertheless they will be fought over. Pakistan has a long history of proposals for irrigation reform, little or none being implemented, except as isolated pilot projects. Thus, to propose major changes in irrigation institutions must be clearly shown to have major benefits to justify the hard battles that must be fought and the goodwill of those who might win those battles for reform. Proponents of irrigation institution reform have always argued the necessity of the reforms and the large gains to be achieved. Perhaps, however, those arguments have not been convincing. This paper will briefly outline the failed attempts at irrigation reform to provide an element of reality to the discussion. It will then proceed to make the case of the urgency of reform in a somewhat different manner to the past. Finally, current major reform proposals will be presented. This paper approaches justification of irrigation reform by focusing on the agricultural growth rate. It does so because that is the critical variable influencing poverty rates and is a significant determinant of over-all economic growth rates. The paper decomposes growth rates and suggests a residual effect of deterioration of the irrigation system that is large and calls for policy and institutional reform. The data are notional, suggesting the usefulness of the approach and paves the way for more detailed empirical analysis and enquiry for the future.

Upcoming Drifts In Bio-Similars

2020 ◽  
Vol 15 ◽  
Author(s):  
Geeta Aggarwal ◽  
Manju Nagpal ◽  
Ameya Sharma ◽  
Vivek Puri ◽  
Gitika Arora Dhingra
Keyword(s):  
Metabolic Diseases ◽  
Market Competition ◽  
Current Status ◽  
Medicinal Products ◽  
The Past ◽  
Biologic Activity ◽  
Emerging Trends ◽  
Regulatory Guidelines ◽  
Food Drug Administration ◽  
Insight Into

Background: Biopharmaceuticals such as Biologic medicinal products have been in clinical use over the past three decades and have benefited towards the therapy of degenerative and critical metabolic diseases. It is forecasted that market of biologics will be going to increase at a rate of 20% per year, and by 2025, more than ˃ 50% of new drug approvals may be biological products. The increasing utilization of the biologics necessitates for cost control, especially for innovators products that have enjoyed a lengthy period of exclusive use. As the first wave of biopharmaceuticals is expired or set to expire, it has led to various opportunities for the expansion of bio-similars i.e. copied versions of original biologics with same biologic activity. Development of biosimilars is expected to promote market competition, meet worldwide demand, sustain the healthcare systems and maintain the incentives for innovation. Methods: Appraisal of published articles from peer reviewed journals, PubMed literature, latest news and guidelines from European Medicine Agency, US Food Drug Administration (FDA) and India are used to identify data for review. Results: Main insight into the quality requirements concerning biologics, current status of regulation of biosimilars and upcoming challenges lying ahead for the upgrading of marketing authorization of bio-similars has been incorporated. Compiled literature on therapeutic status, regulatory guidelines and the emerging trends and opportunities of biosimilars has been thoroughly stated. Conclusion: Updates on biosimilars will support to investigate the possible impact of bio-similars on healthcare market.

Cybersecurity Teamwork: A Review of Current Practices and Suggested Improvements

2020 ◽  
Vol 64 (1) ◽  
pp. 451-455
Author(s):  
Richard J. Simonson ◽  
Joseph R. Keebler ◽  
Mathew Lessmiller ◽  
Tyson Richards ◽  
John C. Lee
Keyword(s):  
Cyber Security ◽  
Cyber Attacks ◽  
Team Science ◽  
The Past ◽  
Insight Into ◽  
Current Practices

As cyber-attacks and their subsequent responses have become more frequent and complex over the past decade, research into the performance and effectiveness of cybersecurity teams has gained an immense amount of traction. However, investigation of teamwork in this domain is lacking due to the exclusion of known team competencies and a lack of reliance on team science. This paper serves to provide insight into the benefit that can be gained from utilizing the extant teamwork literature to improve teams’ research and applications in the domain of cyber-security.

Transfer of photosynthetically fixed carbon between the prokaryotic green alga Prochloron and its ascidian host

1983 ◽  
Vol 34 (3) ◽  
pp. 431 ◽  
Author(s):  
DJ Griffiths ◽  
L Thinh
Keyword(s):  
Light Intensity ◽  
Green Alga ◽  
Host Tissue ◽  
Total Carbon ◽  
Symbiotic Association ◽  
Fixed Carbon ◽  
Low Light ◽  
Ascidian Species ◽  
Dark Fixation ◽  
Efficient Transfer

In the symbiotic association between the prokaryotic green alga Prochloron and three didemnid host species (Diplosoma similis, Lissoclinum bistratum, Trididemnum cyclops), between 6 and 51 % of the total carbon fixed during exposure for 1 h to H14CO3- in the light (150 �E m-2 s-1) becomes associated with the host tissue. Dark fixation of 14CO2 in these ascidian species and in Lissoclinum punctatum never exceeds 6% of photosynthetic fixation at saturating light intensity. The corresponding values for dark fixation of 14CO2 in isolated Prochloron cells fall within the same range. There is very little excretion of photosynthate from whole colonies of the above ascidian species nor from Didemnum molle, Lissoclinum voeltzkowi and Trididemnum miniatum (usually less than 1 % of total photosynthate at saturation light intensity), suggesting an efficient transfer mechanism from Prochloron to host. Evidence from pulse-chase experiments suggests that transfer probably involves the early products of photosynthesis. The extent of transfer of photosynthate between Prochloron and T. cyclops varies with the rate of photosynthetic 14CO2 fixation into the whole colony but there is some transfer even at low light intensities, which strongly limit photosynthesis.

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