Average Net Increase Research Articles

Combining Novel Direction Modulated Brachytherapy Tandem-and-Ovoids Applicators for Treatment Planning of Multi-Institutional Cervical Cancer Cases: Removing Needles in Intracavitary-Interstitial Techniques

Lack of standard guidelines for optimal needle insertion during high-dose-rate (HDR) intracavitary-interstitial (IC-IS) brachytherapy of the cervix means a sophisticated and technical skillset of inserting needles next to IC applicators must be developed to enhance plan quality. This study sought to evaluate the performance of two separate direction modulated brachytherapy (DMBT) tandem applicators used in conjunction with one set of novel DMBT ovoids, uniquely designed to effectively obviate the need for IS needles. A cohort of 32 retrospective clinical HDR brachytherapy plans, from three institutions, were re-planned with Varian's BrachyVision® (v16.1) treatment planning system (BV-TPS), using the latest VEGO® inverse optimization algorithm, with dose heterogeneity accounted for through the AcurosBV®. All plans consisted of IC-IS cases, with a range of 2-4 freehand-loaded needles, with an average prescription dose of 709±53 cGy, and with an average high-risk clinical target volume (HRCTV) of 36.73±17.15 [range 9.8-69.6] cm3. Two DMBT tandem models of 5.4-mm and 8.0-mm thicknesses along with a novel DMBT ovoids design, introduced for the first time, with 9 equi-angled grooves and 10-mm-diameter thickness. During re-planning, the conventional tandems, ovoids/rings, and all of the needles were replaced by one of the two DMBT tandem models and a set of DMBT ovoids. A two-step inverse optimization process was performed to achieve the lowest possible OAR D2cc doses while 1) keeping equivalent target coverage (ΔHRCTV-D90 to within ±0.5%) and 2) maintaining the general pear-shape dose distribution used by the original plans. For all plans, this process was repeated using each of the two DMBT tandem-and-ovoids combinations for a total re-planning of (32×2 =) 64 cases. On average, -47.15±29.61 (-40.40±34.90) cGy, -42.98±26.58 (-41.70±27.40) cGy, and -40.47±25.05 (-32.55±25.30) cGy reductions in D2cc across bladder, rectum, and sigmoid, respectively, were achieved for the 8-mm (5.4-mm) DMBT tandem-and-ovoids combinations while the average ΔHRCTV-D90 was +4.3±2.9 cGy (+0.5%±0.4%). Additionally, D2cc reductions in terms of EQD2 [Gy] were calculated and showed significant reductions of -4.05±2.47 (-3.37±2.83) Gy, -2.71±1.79 (-2.59±1.74) Gy, and -3.27±1.96 (-2.65±2.06) Gy for bladder, rectum, and sigmoid, respectively with an average net increase in total dwell times of 241.0±87.6 seconds at the luxury of avoiding IS needle insertions. It is clinically feasible to obviate the need for IS needles by incorporating the DMBT tandem-and-ovoids while producing lower OAR D2cc doses and maintaining equivalent target coverage.

Optimization of Engineering and Process Parameters for Vermicomposting

Urbanization and population rise considerably increase the generation of solid wastes. The recycling of solid wastes through vermicomposting is a sustainable approach. The current study aimed to investigate the effect of earthworm (Eisenia fetida and Eugilius euganiae)-processed/mixed solid waste manure (vermicompost) on the development, productivity, and chemical characteristics of chili and brinjal in different wooden reactors (R). A mixture of palash leaf litter, biogas slurry, food wastes from a hostel kitchen and households, and municipal solid waste (MSW) were used during the study. The effects of different reactors; process parameters; earthworm cultures, such as R1–R9 with different widths and lengths at a constant height (30 cm); pH, salt, and moisture content; temperature; C:N ratios; N, P, K, and pathogen content; and the type of mono/-polyculture on vermicompost were tested with respect to chili and brinjal production. The average net increase in the worms’ zoomass in reactor R1 at different mixed worm densities (E. fetida + E. eugeniae) under optimum conditions was observed. Compared to a monoculture reactor, the yield of both chili and brinjal were significantly greater in the polyculture reactor with vermicompost soil.

Evaluating the effectiveness of development-limiting boundary control policy: Spatial difference-in-difference analysis

Development-limiting boundaries are widely used in land use regulation in Chinese cities to curb urban sprawl and protect the ecosystem and environment. Land management law in China has recently required the delineation of urban development boundary in national-territory spatial planning of each city. However, limited studies have focused on whether these development-limiting boundaries effectively contain urban land growth in Chinese cities. Hence, effectiveness of these growth management policies remains unclear. This study investigates urban land growth inside and outside the ecological redline and uses spatial difference-in-difference models to evaluate the net effect of boundary on urban land growth in Wuhan. Results revealed that compared with their counterparts grandfathered under the ecological redline control policy, the average net increase of urban land growth inside the ecological redline is 2.2 % after the policy intervention, thereby suggesting that the Ecological Baseline Area regulation is not so useful but pro-growth policy in Urban Construction Area work in place. Inefficient coordination mechanism, technical limitations and the key role of local governments are responsible for the failure of the boundary control policy. Intensive reform on differentiated and urban–rural integrated land use policy design and public supervision mechanism construction is necessary in the future.

Climatic impacts of bushland to cropland conversion in Eastern Africa

Bushlands (Acacia-Commiphora) constitute the largest and one of the most threatened ecosystems in East Africa. Although several studies have investigated the climatic impacts of land changes on local and global climate, the main focus has been on forest loss and the impacts of bushland clearing thus remain poorly understood. Measuring the impacts of bushland loss on local climate is challenging given that changes often occur at fragmented and small patches. Here, we apply high-resolution satellite imagery and land surface flux modeling approaches to unveil the impacts of bushland clearing on surface biophysical properties and its associated effects on surface energy balance and land surface temperature. Our results show that bushland clearing leads to an average reduction in evapotranspiration of 0.4 mm day−1. The changes in surface biophysical properties affected the surface energy balance components with different magnitude. The reduction in latent heat flux was stronger than other surface energy fluxes and resulted in an average net increase in daytime land surface temperature (LST) of up to 1.75 K. These results demonstrate the important impact of bushland-to-cropland conversion on the local climate, as they reveal increases in LST of a magnitude comparable to those caused by forest loss. This finding highlights the necessity of bushland conservation for regulating the land surface temperature in East Africa and, at the same time, warns of the climatic impacts of clearing bushlands for agriculture.

Disodium 2-oxoglutarate promotes carbon flux into astaxanthin and fatty acid biosynthesis pathways in Haematococcus

Improving carbon availability in astaxanthin production is pivotal in Haematococcus industry. In this study, disodium 2-oxoglutarate (2-OG-2Na) was observed to be a potential carbon regulator to increase the astaxanthin content. To illustrate its efficacy in astaxanthin production, key genes and enzyme were analyzed. Upon 2-OG-2Na treatment, genes ipi, bkt and crtR-b were up regulated, concomitantly, carotenoids and astaxanthin content increased by 15.4% and 14.0% at 120 h, respectively; additionally, Acetyl-CoA carboxylase was activated, consistent with 1.27-fold increase in fatty acids content. PUFAs increased earlier as fatty acids assembly gene fad was up-regulated to 20.56. It was also found that cell division was not compromised. Altogether, it was suggested that increased carbon skeletons were re-directed into the astaxanthin and fatty acids biosynthesis pathway. Furthermore, 2-OG-2Na was applied in ten Haematococcus strains. Of these strains, astaxanthin contents were accelerated with average net increase of 10.48%, exhibiting a scalable paradigm for commercial production.

Health Indicators for Renal Replacement Therapy in Saudi Arabia

The renal replacement therapy in Saudi Arabia has 3 main modalities: hemodialysis, peritoneal dialysis, and renal transplantation. Hemodialysis is one of the fastest growing industries of health care providers in Saudi Arabia. ObjectiveWe aimed to review the health indicators of renal replacement therapy. Materials and MethodsWe used the Saudi Center for Organ Transplantation Annual Report 2016. ResultsPatients with end-stage renal disease on hemodialysis and peritoneal dialysis totaled 17,687. Saudi Arabia increased the numbers of dialysis centers and also added 2 more sectors. The Ministry of Health hospitals have 55% of the centers, government non–Ministry of Health has 9%, private and charitable hospitals have 21%, the King Abdullah Hemodialysis Project has 2%, and the outsourcing dialysis programs have 13%. There are 243 dialysis units in Saudi Arabia. Most dialysis centers are in the central region (30%); 27% are in the western region, 19% are in the southern region, 13% are in the eastern region, and 11% are in the northern region. The average net increase of dialysis patients is 6.2% annually and is projected to reach 22,000 by 2020. Causes of renal failure are mainly diabetic nephropathy (40%) and hypertensive nephropathy (38%). Hepatitis C virus positivity is at 12% and hepatitis B surface antigen positivity is at 4%. From the year 2000 renal transplantation from deceased and living donation has tripled in number, with a total of 798 kidneys transplanted. ConclusionRenal replacement therapy is increasing and dialysis center numbers are expected to increase. Renal transplantation numbers have improved both from living and deceased donors but further actions toward the promotion of the organ donation in Saudi Arabia is essential.

Carbon sequestration of plantation in Beijing-Tianjin sand source areas

The Beijing-Tianjin Sand Source Control Project (BTSSCP), a national ecological restoration project, was launched to construct an ecological protection system in the Beijing-Tianjin sand source areas to reduce dust hazards. The carbon sequestration dynamics can be used to assess the ecological effects of an ecological restoration project. Here, we conducted vegetation and soil study to assess the carbon sequestration in the plantations with 10 years old stands in Beijing-Tianjin sand source areas. The results at the site scales indicated that the average net increase of plantation ecosystem carbon stock was 33.8 Mg C ha−1, with an annual increase rate of 3.38 Mg C ha−1 yr−1. The average net increase of carbon varied among regions, vegetation types, and forest management activities. Soil bulk density in the top soil decreased slightly after 10-year implementation of the project. Coniferous forests and shrubs are suitable plant species for sand source areas. Natural restoration in the plantations is a practical and feasible and promising approach for enhancing ecosystem carbon sequestration potential.

Phosphorus micro-dosing as an entry point to sustainable intensification of rice systems in sub-Saharan Africa

Phosphorus (P) deficiency is a major biophysical limitation to rice grain yields in sub-Saharan Africa, and low-cost P management strategies are needed by smallholder farmers to reverse soil fertility decline. On-station field and pot experiments were combined with on-farm testing to evaluate the effect of P micro-dose placement in dry-seeded, dibbled rice on emergence, early vigour and grain yield. Placing a micro-dose of 3–6 kg P ha−1 in the planting hole consistently increased early vigour and grain yield of both a P-efficient and less P-efficient rice genotype. An agronomic efficiency of P fertilizer (AEP) of 356–817 kg grains kg−1 P was achieved with a micro-dose of 3 kg P ha−1. A negative effect on emergence by placing a P micro-dose in the planting hole observed in one experiment was compensated by a higher grain weight per hill. In other experiments, no negative effect on plant emergence under both well-watered and water-stressed conditions and with different P sources was observed even when fertilizers were mixed with seeds. A micro-dose of 20–30 kg of DAP ha−1 placed in the planting hole resulted in an average net increase in profit of $91 to $136 ha−1 and benefit:cost ratio of 3–12 in on-farm experiments. Farmers’ appreciation of the technology was positive but lack of credit, availability of appropriate fertilizers in local agrodealers and increased labour requirements were identified as potential constraints for adoption. P micro-dose placement in the planting hole can be used as an entry point towards sustainable intensification in dry-seeded, dibbled rice systems in SSA, provided it is accompanied by institutional support and mechanization options to increase its adoption potential.

Antagonistic Effects of Ocean Acidification and Rising Sea Surface Temperature on the Dissolution of Coral Reef Carbonate Sediments

Increasing atmospheric CO2 is raising sea surface temperature (SST) and increasing seawater CO2 concentrations, resulting in a lower oceanic pH (ocean acidification; OA), which is expected to reduce the accretion of coral reef ecosystems. Although sediments comprise most of the calcium carbonate (CaCO3) within coral reefs, no in situ studies have looked at the combined effects of increased SST and OA on the dissolution of coral reef CaCO3 sediments. In situ benthic chamber incubations were used to measure dissolution rates in permeable CaCO3 sands under future OA and SST scenarios in a coral reef lagoon on Australia’s Great Barrier Reef (Heron Island). End of century (2100) simulations (temperature +2.7°C and pH -0.3) shifted carbonate sediments from net precipitating to net dissolving. Warming increased the rate of benthic respiration (R) by 29% per 1°C and lowered the ratio of productivity to respiration (P/R; ΔP/R = -0.23), which increased the rate of CaCO3 sediment dissolution (average net increase of 18.9 mmol CaCO3 m-2 d-1 for business as usual scenarios). This is most likely due to the influence of warming on benthic P/R which, in turn, was an important control on sediment dissolution through the respiratory production of CO2. The effect of increasing CO2 on CaCO3 sediment dissolution (average net increase of 6.5 mmol CaCO3 m-2 d-1 for business as usual scenarios) was significantly less than the effect of warming. However, the combined effect of increasing both SST and pCO2 on CaCO3 sediment dissolution was non-additive (average net increase of 5.6 mmol CaCO3 m-2 d-1) due to the different responses of the benthic community. This study highlights that benthic biogeochemical processes such as metabolism and associated CaCO3 sediment dissolution respond rapidly to changes in SST and OA, and that the response to multiple environmental changes are not necessarily additive.

Simulation Of Quitting Smoking In The Military Shows Higher Lifetime Medical Spending More Than Offset By Productivity Gains

Despite the documented benefits of quitting smoking, studies have found that smokers who quit may have higher lifetime medical costs, in part because of increased risk for medical conditions, such as type 2 diabetes, brought on by associated weight gain. Using a simulation model and data on 612,332 adult smokers in the US Department of Defense's TRICARE Prime health plan in 2008, we estimated that cessation accompanied by weight gain would increase average life expectancy by 3.7 years, and that the average lifetime reduction in medical expenditures from improved health ($5,600) would be offset by additional expenditures resulting from prolonged life ($7,300). Results varied by age and sex: For females ages 18-44 at time of cessation, there would be net savings of $1,200 despite additional medical expenditures from prolonged life. Avoidance of weight gain after quitting smoking would increase average life expectancy by four additional months and reduce mean extra spending resulting from prolonged life by $700. Overall, the average net lifetime health care cost increase of $1,700 or less per ex-smoker would be modest and, for employed people, more than offset by even one year's worth of productivity gains. These results boost the case for smoking cessation programs in the military in particular, along with not selling cigarettes in commissaries or at reduced prices.

Predicted Effect of Landscape Position on Wildlife Habitat Value of Conservation Reserve Enhancement Program Wetlands in a Tile‐drained Agricultural Region

AbstractJustification for investment in restored or constructed wetland projects are often based on presumed net increases in ecosystem services. However, quantitative assessment of performance metrics is often difficult and restricted to a single objective. More comprehensive performance assessments could help inform decision‐makers about trade‐offs in services provided by alternative restoration program design attributes. The primary goal of the Iowa Conservation Reserve Enhancement Program is to establish wetlands that efficiently remove nitrates from tile‐drained agricultural landscapes. A secondary objective is provision of wildlife habitat. We used existing wildlife habitat models to compare relative net change in potential wildlife habitat value for four alternative landscape positions of wetlands within the watershed. Predicted species richness and habitat value for birds, mammals, amphibians, and reptiles generally increased as the wetland position moved lower in the watershed. However, predicted average net increase between pre‐ and post‐project value was dependent on taxonomic group. The increased average wetland area and changes in surrounding upland habitat composition among landscape positions were responsible for these differences. Net change in predicted densities of several grassland bird species at the four landscape positions was variable and species‐dependent. Predicted waterfowl breeding activity was greater for lower drainage position wetlands. Although our models are simplistic and provide only a predictive index of potential habitat value, we believe such assessment exercises can provide a tool for coarse‐level comparisons of alternative proposed project attributes and a basis for constructing informed hypotheses in auxiliary empirical field studies.

Acute changes in sputum collected from exposed human subjects in mining conditions

Neprilysin (NEP) is a key cell surface peptidase in the maintenance of airway homeostasis and the development of pulmonary disorders. However, little information is available about the effect of particulate matter (PM) on airway NEP. In this controlled human exposure study, changes in induced sputum were measured in 11 subjects at baseline, overshot (OS) mucking, and diesel exhaust (DE) exposure days. Neither OS condition nor DE exposure was found to induce significant changes in total protein, but DE induced significant increases in cell numbers of macrophages and epithelium. Moreover, significant increases in soluble NEP were observed following OS mining dust particulates (0.43 ± 0.06 nmol/μg protein/min; p = .023) and DE exposure (0.40 ± 0.03 nmol/μg protein/min; p = .035) when compared with the baseline control (0.30 ± 0.04 nmol/μg protein/min), with 42% and 31% average net increase, respectively. Pearson’s correlation analyses indicated that sputum NEP activity was significantly associated with personal exposure product (elemental carbon concentration [mg/m3] × time [min]; C × T). The data suggest that changes in NEP activity may be an early, accurate endpoint for airway epithelial injury and provide a new insight into the mechanism of airway effects following particulate exposure.

An assessment of different fertilization regimes in three boreal coniferous stands

In 1981–82 three field experiments were established with the aim of elucidating (i) the growth response of middle-aged coniferous stands at different fertilization intensities and, hence, the economic outcomes; and (ii) the need to add nutrients other than nitrogen (N). Nutrient additions were performed at intervals of two, four, six and eight years. The experiments were established on typical podzolized and N-limited mor-humus sites, two in Scots pine (Pinus sylvestris L.) stands and one in a Norway spruce (Picea abies (L.) Karst.) stand, at three different locations in Sweden. The ages of the stands were 65–70 years at the time of establishment. Growth responses were calculated after a 22-year study period. The growth responses were significant in all treatments. The addition of nutrients other than N did not affect stem growth at any of the sites. The growth response tended to increase with decreasing application interval. The results also revealed that the efficiency of fertilization is reduced as the interval between fertilizations is shortened. Accordingly, the growth effect per kg of added N was negatively correlated to fertilization intensity. The least intensive fertilization regime (an eight-year interval) resulted in an average net increase in C sequestration of 35 kg per kg N added. The profitability, in terms of internal rate of return, the present net value at different interest rates and the cost of production, i.e. the cost to produce one extra m under the different N regimes, are presented and discussed.3

Job creation and labor reform in Latin America

This paper studies the effects of labor-regulation reform using data for 10,396 firms from 14 Latin American countries. Firms are asked both how many permanent workers they would have hired and how many they would have terminated if labor regulations were made more flexible. I find that making labor regulations more flexible would lead to an average net increase of 2.08 percent in total employment. Firms with fewer than 20 employees would benefit the most, with average gains in net employment of 4.27 percent. Countries with more regulated labor markets would experience larger gains in total employment. These larger gains in total employment, however, would be achieved through higher rates of hiring and higher rates of termination. These results may explain why there is substantial opposition to labor reforms despite the predicted gains in efficiency and total employment.

Geospatial Analysis of Barrier Island Width of Two Segments of the Outer Banks, North Carolina, USA: Anthropogenic Curtailment of Natural Self-Sustaining Processes

A comparison of two sections of the Outer Banks, North Carolina, USA (Pea Island and Avon-Buxton areas), reveals the importance of the interplay between oceanic and estuarine shoreline dynamics to long-term changes in barrier island width. From 1852 to 1998, the northern portion of Pea Island experienced an average net increase in width of 431 m (3 m/y); this area experienced low to moderate rates of oceanic shoreline erosion and high rates of back-barrier land accretion via overwash and formation of flood tidal delta islands. In contrast, between 1852 and 1998, the width of the southern portion of Pea Island and the Avon-Buxton area decreased an average of 515 m (4 m/y) and 594 m (4 m/y), respectively, because of high rates of oceanic shoreline erosion and variable changes in estuarine shoreline accretion and erosion. Net gain or net loss of barrier island width is strongly dependent on the natural depositional processes of overwash and flood tide delta formation. Anthropogenic modifications to the barrier island, such as construction of barrier dune ridges, planting of stabilizing vegetation, and urban development, can curtail or even eliminate the natural, self-sustaining processes of overwash and inlet dynamics.

Health economics of renal replacement therapy: Perspectives from Singapore

The prevalence of end-stage renal disease (ESRD) in Singapore is high and projected to increase sharply due to the aging population and the high prevalence of diabetes. The number of patients treated with dialysis was projected to rise from 2633 in 1999 to nearly 6000 in the year 2010. The cost of dialysis provision was estimated to increase 2.5-fold from US dollar 90 million in 1999 to US dollar 241 million in 2010. To address this, the Singapore Ministry of Health launched three initiatives in the year 2000: First, to reduce the incidence of ESRD through (1) primary prevention of diabetes, (2) community-based screening to facilitate early detection of patients with diabetes, (3) improving glycemic and blood pressure (BP) control of diabetics in the primary care setting, and (4) the establishment of dedicated Renal Retardation clinics to optimize BP control (and glycemic control for diabetics), and reduce the level of proteinuria in patients at high risk of ESRD development. Second, to increase the percentage of ESRD patients treated with continuous ambulatory peritoneal dialysis (CAPD), which is a lower-cost modality compared with hemodialysis; and third, amendments to the existing opt-out legislation for organ procurement for transplantation to increase the supply of kidneys for cadaveric renal transplant.

Effect of short-term treatment with low dosages of the proton-pump inhibitor omeprazole on serum chromogranin A levels in man.

Measurement of chromogranin A (CgA) levels in blood can be used to monitor neuroendocrine tumors (NETs). CgA levels may also be elevated in several other endocrine and non-endocrine diseases. It is well known that drugs affecting acid gastric secretion can increase gastrin. Proton-pump inhibitors are extensively used but only a few data have been reported on their effects on CgA secretion. The aim of the study was to evaluate the short-term effect of low dosages of omeprazole (OM) on CgA levels and to sensitize endocrinologists to possible false positive values of CgA in order to prevent expensive diagnostic work-up in searching for NETs. Thirty-five female and nine male in-patients (18-81 years) were studied. Mild or severe hypertension in 20 patients needed therapy. Endocrine and metabolic diseases were diagnosed in the majority of patients. CgA levels were evaluated before and during OM therapy (10 mg/day, orally). Without OM therapy, CgA levels were 64+/-6 microg/l. Elevated baseline CgA levels were found in nine subjects. CgA levels were significantly related to age (P<0.001), creatinine levels (P=0.03) and the severity of hypertension (P=0.002). On short-term OM therapy (n=42; 18.8+/-2.4 days; range 5-90 days) a significant (P<0.001) increase in CgA (145+/-22 microg/l) from baseline (63+/-7 microg/l) levels was found. The average net CgA increase on short-term OM therapy was 93+/-20 microg/l. There was a significant correlation between baseline CgA levels and CgA increase on short-term OM therapy (P=0.004) but not between the increase in CgA and the duration of the therapy. An increase in CgA levels quickly follows the start of low dosages of OM. This release is more pronounced when the baseline CgA levels are already increased by slight renal insufficiency or severe hypertension. In this common clinical situation an intensive work-up for NETs is not justified before reassessment of CgA after the withdrawal of OM.

Effect of tiered prescription copayments on the use of preferred brand medications.

Health plans are increasingly using more open drug formularies that offer differential prescription copayments as an incentive to enrollees to use brands that plans prefer. How much this financial incentive affects use of preferred brands has not been widely reported. The aim of this study was to estimate the effect of tiered copayments on the choice between preferred and nonpreferred brand medications. Longitudinal logistic regression analyses of pharmacy claims from 1998 and 1999 comparing concurrent groups that were or were not exposed to tiered copayments. Enrollees in four independent physician practice association model health plans who had pharmacy claims for angiotensin converting enzyme inhibitors (ACEI), proton pump inhibitors (PPI), or hydroxymethylglutaryl coenzyme A reductase inhibitors (STATINS). Change in the percentage of prescription claims that were for preferred brands. Regression adjusted estimates of the average net increase in the percentage use of preferred brands of ACEI, PPI and STATIN from first quarter 1998 to third quarter 1999 attributed to tiered prescription copayments were 13.3 (P = 0.001), 8.9 (P = 0.03), and 6.0 (P <0.001) percentage points, respectively. Tiered prescription copayments were associated with a significant shift from nonpreferred to preferred brand medications. This type of financial incentive can help purchasers providing open access drug benefits by steering use of medications toward lower cost brands. The clinical effects of changes in medication use brought about differential copayments warrant further investigation.

Fatty acids profile in a high cell density culture of arachidonic acid-richParietochloris incisa (Trebouxiophyceae, chlorophyta) exposed to high PFD

The changes in arachidonic acid (AA) and fatty acids profiles along the growth curve ofParietochloris incisa, a coccoid snow green alga, were studied in a 2.8 cm light-path flat photobiorcactor, exposed to strong photon flux density [PFD, 2400 μEmol/(m2·s)]. Sixteen fatty acids were identified by gas chromatography showing that AA was the dominant fatty acid (33%–41%) followed by linoleic acid (17%–21%). AA content was closely investigated with respect to total fatty acids (TFA), ash free dry weight (AFDW) of cell mass as well as total culture content. These parameters were influenced significantly in a similar manner by culture growth phase, i.e., slightly decreasing in the lag period, gradually increasing in the logarithmic phase, becoming maximal at the early stationary phase, starting to decrease at the late stationary phase, sharply dropping at the decline phase. The increase in AA per culture volume during the logarithmic phase was not only associated with the increase in AFDW but also connected with a corresponding increase in AA/TFA, TFA/AFDW as well as AA/AFDW. The sharp decrease in AA content of the culture during the decline phase was mainly due to the decrease in AA/TFA, TFA/AFDW and AA/AFDW, although AFDW declined only a small extent. Maximal AA concentration, obtained at the early stationary phase, was 900 mg/L culture volume, and the average daily net increase of AA during 9 days logarithmic growth was 1.7 g/(m2·day). Therefore, harvesting prior to the decline phase in a batch culture, or at steady state in continuous culture mode seems best for high AA production. The latter possibility was also further confirmed by continuous culture with 5 gradients of harvesting rate.

Elevated CO2and plant structure: a review

SummaryConsequences of increasing atmospheric CO2concentration on plant structure, an important determinant of physiological and competitive success, have not received sufficient attention in the literature. Understanding how increasing carbon input will influence plant developmental processes, and resultant form, will help bridge the gap between physiological response and ecosystem level phenomena. Growth in elevated CO2alters plant structure through its effects on both primary and secondary meristems of shoots and roots. Although not well established, a review of the literature suggests that cell division, cell expansion, and cell patterning may be affected, driven mainly by increased substrate (sucrose) availability and perhaps also by differential expression of genes involved in cell cycling (e.g. cyclins) or cell expansion (e.g. xyloglucan endotransglycosylase). Few studies, however, have attempted to elucidate the mechanistic basis for increased growth at the cellular level. Regardless of specific mechanisms involved, plant leaf size and anatomy are often altered by growth in elevated CO2, but the magnitude of these changes, which often decreases as leaves mature, hinges upon plant genetic plasticity, nutrient availability, temperature, and phenology. Increased leaf growth results more often from increased cell expansion rather than increased division. Leaves of crop species exhibit greater increases in leaf thickness than do leaves of wild species. Increased mesophyll and vascular tissue cross‐sectional areas, important determinates of photosynthetic rates and assimilate transport capacity, are often reported. Few studies, however, have quantified characteristics more reflective of leaf function such as spatial relationships among chlorenchyma cells (size, orientation, and surface area), intercellular spaces, and conductive tissue. Greater leaf size and/or more leaves per plant are often noted; plants grown in elevated CO2exhibited increased leaf area per plant in 66% of studies, compared to 28% of observations reporting no change, and 6% reported a decrease in whole plant leaf area. This resulted in an average net increase in leaf area per plant of 24%. Crop species showed the greatest average increase in whole plant leaf area (+ 37%) compared to tree species (+ 14%) and wild, nonwoody species (+ 15%). Conversely, tree species and wild, nontrees showed the greatest reduction in specific leaf area (– 14% and – 20%) compared to crop plants (– 6%). Alterations in developmental processes at the shoot apex and within the vascular cambium contributed to increased plant height, altered branching characteristics, and increased stem diameters. The ratio of internode length to node number often increased, but the length and sometimes the number of branches per node was greater, suggesting reduced apical dominance. Data concerning effects of elevated CO2on stem/branch anatomy, vital for understanding potential shifts in functional relationships of leaves with stems, roots with stems, and leaves with roots, are too few tomake generalizations. Growth in elevated CO2typically leads to increased root length, diameter, and altered branching patterns. Altered branching characteristics in both shoots and roots may impact competitive relationships above and below the ground. Understanding how increased carbon assimilation affects growth processes (cell division, cell expansion, and cell patterning) will facilitate a better understanding of how plant form will change as atmospheric CO2increases. Knowing how basic growth processes respond to increased carbon inputs may also provide a mechanistic basis for the differential phenotypic plasticity exhibited by different plant species/functional types to elevated CO2.