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Net Contribution (net + contribution)
Selected AbstractsNet regional ecosystem CO2 exchange from airborne and ground-based eddy covariance, land-use maps and weather observationsGLOBAL CHANGE BIOLOGY, Issue 3 2007F. MIGLIETTA Abstract Measurements of regional net ecosystem exchange (NEE) were made over a period of 21 days in summer 2002 in the South-Central part of the Netherlands and extrapolated to an area of 13 000 km2 using a combination of flux measurements made by a Sky Arrow ERA research aircraft, half-hourly eddy covariance data from four towers, half-hourly weather data recorded by three weather stations and detailed information on regional land use. The combination of this type of information allowed to estimate the net contribution of the terrestrial ecosystems to the overall regional carbon flux and to map dynamically the temporal and spatial variability of the fluxes. A regional carbon budget was calculated for the study period and the contributions of the different land uses to the overall regional flux, were assessed. Ecosystems were, overall, a small source of carbon to the atmosphere equivalent to to 0.23±0.025 g C m,2 day,1. When considered separately, arable and grasslands were a source of, respectively, 0.68±0.022 and 1.28±0.026 g C m,2 day,1. Evergreen and deciduous forests were instead a sink of ,1.42±0.015 g C m,2 day,1. During the study period, forests offset approximately 3.5% of anthropogenic carbon emission estimates obtained from inventory data. Lacking of a robust validation, NEE values obtained with this method were compared with independent state of art estimates of the regional carbon balance that were obtained by applying a semi-empirical model of NEE driven by MODIS satellite fAPAR data. The comparison showed an acceptable matching for the carbon balance of forest that was a sink in both cases, while a much larger difference for arable and grassland was found. Those ecosystems were a sink for satellite-based estimates while they were a source for the combined aircraft and tower estimates. Possible causes of such differences are discussed and partly addressed. The importance of new methods for determining carbon balance at the regional scale, is outlined. [source] The net contribution of the Mauritian export processing zone using benefit,cost analysisJOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 3 2009Rojid Sawkut Abstract An EPZ is basically no more than a device whereby imports, to be used in the production of exports, can be acquired by manufacturers on a bonded duty-free basis. They are literally industrial zones with special incentives to attract foreign investors in which imported materials undergo some degree of processing before being exported again. The logic behind these zones was the creation of an area in which domestic policies do not hold and in which, therefore, a government could implement policies designed to enable individual firms to invest profitably on the basis of a country's comparative advantage. However, although there is significant literature on the impact of EPZs on host countries, nevertheless, the evidence has mainly been concerned with their benefits and costs and has stopped short of formal benefit-cost analysis. In essence, what the empirical studies have lacked, including those done on the Mauritius Export Processing Zone (MEPZ), has been an analytical framework within which the benefits and costs of EPZs can be identified conceptually and quantified empirically. In this respect, the objective of the current paper is to formally attempt to calculate the net contribution of the MEPZ using a modified version of the enclave model put forward by Warr (1988). The results show that although Mauritius has been able to attain its objective of reducing employment and raising foreign exchange through the creation of the EPZ, yet overall the EPZ has cost more to the economy than the benefits it has conferred to the economy. This is principally because of the incentives that were given to the producers working in the EPZ sector. The costs of these incentives were higher than the overall returns obtained from the sector. The two variables that negatively contributed to the sector were domestic borrowings and electricity usage. Copyright © 2008 John Wiley & Sons, Ltd. [source] Deletion of either CD55 or CD97 ameliorates arthritis in mouse modelsARTHRITIS & RHEUMATISM, Issue 4 2010Robert M. Hoek Objective CD55 (decay-accelerating factor) is best known for its role in the negative regulation of the complement system. Indeed, lack of this molecule leads to disease aggravation in many autoimmune disease models. However, CD55 is abundantly present on fibroblast-like synoviocytes and is also a ligand of the adhesion-class heptahelical receptor CD97, which is expressed by infiltrating macrophages. Treatment with antibodies to CD97 ameliorates the collagen-induced model of rheumatoid arthritis (RA) in DBA/1 mice, but the net contribution of CD55 is unknown. This study was undertaken to investigate the role of CD55 in experimental RA. Methods Arthritis was induced in wild-type, CD55,/,, and CD97,/, mice using collagen-induced and K/BxN serum,transfer models. Incidence of arthritis was monitored over time, and disease activity was assessed by clinical and immunohistochemical evaluation. Results In contrast to observations in many inflammatory disease models, lack of CD55 resulted in decreased arthritis in experimental models of RA. Consistent with the previously reported effects of anti-CD97 antibody treatment, CD97,/, mice had reduced arthritis activity compared with wild-type controls. Conclusion Our findings indicate that the lack of CD55 or CD97 in 2 different models of arthritis increases resistance to the disease. These findings provide insight into a role for CD55 interaction with CD97 in the pathogenesis of RA and suggest that therapeutic strategies that disrupt CD55/CD97 may be clinically beneficial. [source] Protein tyrosine phosphatases in Chaetopterus egg activationDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 5-6 2003Shantá D. Hinton Changes in protein tyrosine phosphorylation are an essential aspect of egg activation after fertilization. Such changes result from the net contributions of both tyrosine kinases and phosphatases (PTP). This study was conducted to determine what role(s) PTP may have in egg activation. We identified four novel PTP in Chaetopterus pergamentaceus oocytes, cpPTPNT6, cpPTPNT7, cpPTPR2B, and cpPTPR2A, that have significant homology to, respectively, human PTP,, -,, -D2 and -BAS. The first two are cytosolic and the latter two are transmembrane. Several PTP inhibitors were tested to see if they would affect Chaetopterus pergamentaceus fertilization. Eggs treated with ,-bromo-4-hydroxyacetophenone (PTP inhibitor 1) exhibited microvillar elongation, which is a sign of cortical changes resulting from activation. Those treated with Na3VO4 underwent full parthenogenetic activation, including polar body formation and pseudocleavage and did so independently of extracellular Ca2+, which is required for the Ca2+ oscillations that initiate development after fertilization. Fluorescence microscopy identified phosphotyrosine-containing proteins in the cortex and around the nucleus of vanadate-activated eggs, whereas in fertilized eggs they were concentrated only in the cortex. Immunoblots of vanadate-activated and fertilized eggs showed tyrosine hyperphosphorylation of approximately140 kDa protein. These results suggest that PTP most likely maintain the egg in an inactive state by dephosphorylation of proteins independent of the Ca2+ oscillations in the activation process. [source] | ||||||||||