Separating active and passive influences on stomatal control of transpiration.

Science.gov (United States)

McAdam, Scott A M; Brodribb, Timothy J

2014-04-01

Motivated by studies suggesting that the stomata of ferns and lycophytes do not conform to the standard active abscisic acid (ABA) -mediated stomatal control model, we examined stomatal behavior in a conifer species (Metasequoia glyptostroboides) that is phylogenetically midway between the fern and angiosperm clades. Similar to ferns, daytime stomatal closure in response to moderate water stress seemed to be a passive hydraulic process in M. glyptostroboides immediately alleviated by rehydrating excised shoots. Only after prolonged exposure to more extreme water stress did active ABA-mediated stomatal closure become important, because foliar ABA production was triggered after leaf turgor loss. The influence of foliar ABA on stomatal conductance and stomatal aperture was highly predictable and additive with the passive hydraulic influence. M. glyptostroboides thus occupies a stomatal behavior type intermediate between the passively controlled ferns and the characteristic ABA-dependent stomatal closure described in angiosperm herbs. These results highlight the importance of considering phylogeny as a major determinant of stomatal behavior.

Phytomelatonin receptor PMTR1-mediated signaling regulates stomatal closure in Arabidopsis thaliana.

Science.gov (United States)

Wei, Jian; Li, Dong-Xu; Zhang, Jia-Rong; Shan, Chi; Rengel, Zed; Song, Zhong-Bang; Chen, Qi

2018-04-27

Melatonin has been detected in plants in 1995; however, the function and signaling pathway of this putative phytohormone are largely undetermined due to a lack of knowledge about its receptor. Here, we discovered the first phytomelatonin receptor (CAND2/PMTR1) in Arabidopsis thaliana and found that melatonin governs the receptor-dependent stomatal closure. The application of melatonin induced stomatal closure through the heterotrimeric G protein α subunit-regulated H 2 O 2 and Ca 2+ signals. The Arabidopsis mutant lines lacking AtCand2 that encodes a candidate G protein-coupled receptor were insensitive to melatonin-induced stomatal closure. Accordingly, the melatonin-induced H 2 O 2 production and Ca 2+ influx were completely abolished in cand2. CAND2 is a membrane protein that interacts with GPA1 and the expression of AtCand2 was tightly regulated by melatonin in various organs and guard cells. CAND2 showed saturable and specific 125 I-melatonin binding, with apparent K d (dissociation constant) of 0.73 ± 0.10 nmol/L (r 2  = .99), demonstrating this protein is a phytomelatonin receptor (PMTR1). Our results suggest that the phytomelatonin regulation of stomatal closure is dependent on its receptor CAND2/PMTR1-mediated H 2 O 2 and Ca 2+ signaling transduction cascade. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Separating Active and Passive Influences on Stomatal Control of Transpiration[OPEN

Science.gov (United States)

McAdam, Scott A.M.; Brodribb, Timothy J.

2014-01-01

Motivated by studies suggesting that the stomata of ferns and lycophytes do not conform to the standard active abscisic acid (ABA) -mediated stomatal control model, we examined stomatal behavior in a conifer species (Metasequoia glyptostroboides) that is phylogenetically midway between the fern and angiosperm clades. Similar to ferns, daytime stomatal closure in response to moderate water stress seemed to be a passive hydraulic process in M. glyptostroboides immediately alleviated by rehydrating excised shoots. Only after prolonged exposure to more extreme water stress did active ABA-mediated stomatal closure become important, because foliar ABA production was triggered after leaf turgor loss. The influence of foliar ABA on stomatal conductance and stomatal aperture was highly predictable and additive with the passive hydraulic influence. M. glyptostroboides thus occupies a stomatal behavior type intermediate between the passively controlled ferns and the characteristic ABA-dependent stomatal closure described in angiosperm herbs. These results highlight the importance of considering phylogeny as a major determinant of stomatal behavior. PMID:24488969

Carbonic anhydrases are upstream regulators of CO2-controlled stomatal movements in guard cells

KAUST Repository

Hu, Honghong

2009-12-13

The continuing rise in atmospheric CO2 causes stomatal pores in leaves to close and thus globally affects CO2 influx into plants, water use efficiency and leaf heat stress. However, the CO2-binding proteins that control this response remain unknown. Moreover, which cell type responds to CO2, mesophyll or guard cells, and whether photosynthesis mediates this response are matters of debate. We demonstrate that Arabidopsis thaliana double-mutant plants in the beta-carbonic anhydrases betaCA1 and betaCA4 show impaired CO2-regulation of stomatal movements and increased stomatal density, but retain functional abscisic-acid and blue-light responses. betaCA-mediated CO2-triggered stomatal movements are not, in first-order, linked to whole leaf photosynthesis and can function in guard cells. Furthermore, guard cell betaca-overexpressing plants exhibit instantaneous enhanced water use efficiency. Guard cell expression of mammalian alphaCAII complements the reduced sensitivity of ca1 ca4 plants, showing that carbonic anhydrase-mediated catalysis is an important mechanism for betaCA-mediated CO2-induced stomatal closure and patch clamp analyses indicate that CO2/HCO3- transfers the signal to anion channel regulation. These findings, together with ht1-2 (ref. 9) epistasis analysis demonstrate that carbonic anhydrases function early in the CO2 signalling pathway, which controls gas-exchange between plants and the atmosphere.

Balancing Water Uptake and Loss through the Coordinated Regulation of Stomatal and Root Development.

Directory of Open Access Journals (Sweden)

Christopher Hepworth

Full Text Available Root development is influenced by nutrient and water availabilities. Plants are able to adjust many attributes of their root in response to environmental signals including the size and shape of the primary root, lateral roots and root hairs. Here we investigated the response of roots to changes in the levels of leaf transpiration associated with altered stomatal frequency. We found that plants with high stomatal density and conductance produce a larger rooting area and as a result have enhanced phosphate uptake capacity whereas plants with low stomatal conductance produce a smaller root. Manipulating the growth environment of plants indicated that enhanced root growth is most likely a result of an increased demand for water rather than phosphate. Plants manipulated to have an increase or reduction in root hair growth show a reduction or increase respectively, in stomatal conductance and density. Our results demonstrate that plants can balance their water uptake and loss through coordinated regulation of both stomatal and root development.

The Ecophysiology Of A Pinus Ponderosa Ecosystem Exposed To High Tropospheric Ozone: Implications For Stomatal And Non-Stomatal Ozone Fluxes

Science.gov (United States)

Fares, S.; McKay, M.; Goldstein, A.

2008-12-01

Ecosystems remove ozone from the troposphere through both stomatal and non-stomatal deposition. The portion of ozone taken up through stomata has an oxidative effect causing damage. We used a multi-year dataset to assess the physiological controls over ozone deposition. Environmental parameters, CO2 and ozone fluxes were measured continuously from January 2001 to December 2006 above a ponderosa pine plantation near Blodgett Forest, Georgetown, California. We studied the dynamic of NEE (Net Ecosystem Exchange, -838 g C m-2 yr-1) and water evapotranspiration on an annual and daily basis. These processes are tightly coupled to stomatal aperture which also controlled ozone fluxes. High levels of ozone concentrations (~ 100 ppb) were observed during the spring-summer period, with corresponding high levels of ozone fluxes (~ 30 μmol m-2 h-1). During the summer season, a large portion of the total ozone flux was due to non-stomatal processes, and we propose that a plant physiological control, releasing BVOC (Biogenic Volatile Organic Compounds), is mainly responsible. We analyzed the correlations of common ozone exposure metrics based on accumulation of concentrations (AOT40 and SUM0) with ozone fluxes (total, stomatal and non-stomatal). Stomatal flux showed poorer correlation with ozone concentrations than non-stomatal flux during summer and fall seasons, which largely corresponded to the growing period. We therefore suggest that AOT40 and SUM0 are poor predictors of ozone damage and that a physiologically based metric would be more effective.

The dilemma of saving water or being cool: What determines the stomatal response under a changing climate?

Science.gov (United States)

Haghighi, Erfan; Kirchner, James W.; Entekhabi, Dara

2017-04-01

Stomata play a critical role in terrestrial water and carbon cycles, regulating the trade-off between photosynthetic carbon gain and water loss in leaves. They adjust their aperture in response to a number of physiological and environmental factors, yet the mechanisms driving this response, particularly under climate extremes, remain poorly understood. Partial or complete stomatal closure reduces plant water stress under water-limited or high atmospheric evaporative demand conditions, but at the cost of reduced productivity, elevated heat, leaf shedding, and mortality. A proper account of such complex stomatal behavior is of particular importance for current ecosystem models that poorly capture observed vegetation responses in the context of climate change which is predicted to cause more frequent and intense temperature extremes along with an increase in the frequency of drought in many regions in the future. This study seeks to explore stomatal responses to environmental change accounted for by a varying soil-plant resistance under different atmospheric and soil moisture conditions. To this end, we developed a physically based transpiration model that couples stomatal control of leaf gas exchange to the leaf surface energy balance and the entire plant hydraulic system by considering the interdependence of the guard cell water potential (or turgor pressure) and transpiration rates. Model simulations of diurnal variations in transpiration rates were in good agreement with field observations, and facilitated quantitative prediction of stomatal and xylem flow regulation under a wide range of environmental conditions. Preliminary results demonstrate how soil and plant hydraulic conductances regulating stomatal opening and closure can help mitigate climatic water deficit (e.g., at midday) by boosting evaporative cooling. Our results are expected to advance physical understanding of the water cycle in the soil-plant-atmosphere continuum, and shed light on observed

Effect of nitrogen supply on transpiration and stomatal behaviour of beans (Phaseolus vulgaris L. )

Energy Technology Data Exchange (ETDEWEB)

Shimshi, D

1970-01-01

The effect of nitrogen supply on the transpiration rate and stomatal opening of potted bean plants was studied in a series of experiments. The transpiration rates of N-supplied plants were higher than those of N-deficient plants when soil moisture was relatively high; as soil moisture approached the wilting range, the transpiration rates of N-supplied plants dropped to below those of N-deficient plants. In spite of the marked differences in transpiration rates, as influenced by soil moisture and nitrogen supply, the stomata appeared closed. By coating the upper or lower surfaces of the leaves with a vapor-impervious compound it was shown that stomatal apertures below the limit of microscopic resolution control the rate of transpiration. Under conditions that encourage stomatal opening (covering the plants with transparent plastic bags), the stomata of the N-deficient plants opened to a lesser degree than those of N-supplied plants. There was some evidence that when stomata were visibly open, transpiration rates were regulated by the degree of plant hydration rather than by the degree of stomatal opening. It is concluded that N-deficient plants fail to open their stomata as widely and to close them as tightly as N-supplied plants. 8 references, 2 tables.

Acquired changes in stomatal characteristics in response to ozone during plant growth and leaf development of bush beans (Phaseolus vulgaris L.) indicate phenotypic plasticity

International Nuclear Information System (INIS)

Elagoez, Vahram; Han, Susan S.; Manning, William J.

2006-01-01

Bush bean (Phaseolus vulgaris L.) lines 'S156' (O 3 -sensitive)/'R123' (O 3 -tolerant) and cultivars 'BBL 290' (O 3 -sensitive)/'BBL 274' (O 3 -tolerant) were used to study the effects of O 3 on stomatal conductance (g s ), density, and aperture size on leaf and pod surfaces with the objective of establishing links between the degree of plant sensitivity to O 3 and plasticity of stomatal properties in response to O 3 . Studies in open-top chambers (OTCs) and in continuously stirred tank reactors (CSTRs) established a clear relationship between plant developmental stages, degrees of O 3 sensitivity and g s : while 'S156' had higher g s rates than 'R123' earlier in development, similar differences between 'BBL 290' and 'BBL 274' were observed at later stages. G s rates on the abaxial leaf surfaces of 'S156' and 'BBL 290', accompanied by low leaf temperatures, were significantly higher than their O 3 -tolerant counterparts. Exposure to O 3 in CSTRs had greater and more consistent impacts on both stomatal densities and aperture sizes of O 3 -sensitive cultivars. Stomatal densities were highest on the abaxial leaf surfaces of 'S156' and 'BBL 290' at higher O 3 concentrations (60 ppb), but the largest aperture sizes were recorded on the adaxial leaf surfaces at moderate O 3 concentrations (30 ppb). Exposure to O 3 eliminated aperture size differences on the adaxial leaf surfaces between sensitive and tolerant cultivars. Regardless of sensitivity to O 3 and treatment regimes, the smallest aperture sizes and highest stomatal densities were found on the abaxial leaf surface. Our studies showed that O 3 has the potential to affect stomatal plasticity and confirmed the presence of different control mechanisms for stomatal development on each leaf surface. This appeared to be more evident in O 3 -sensitive cultivars. - O 3 has the potential to affect stomatal development and the presence of different control mechanisms on each leaf surface is confirmed

Elevated air movement enhances stomatal sensitivity to abscisic acid in leaves developed at high relative air humidity

Directory of Open Access Journals (Sweden)

Dália R.A. Carvalho

2015-05-01

Full Text Available High relative air humidity (RH ≥ 85% during growth leads to stomata malfunctioning, resulting in water stress when plants are transferred to conditions of high evaporative demand. In this study, we hypothesized that an elevated air movement (MOV 24 h per day, during the whole period of leaf development would increase abscisic acid concentration ([ABA] enhancing stomatal functioning. Pot rose ‘Toril’ was grown at moderate (61% or high (92% RH combined with a negligible MOV or with a continuous MOV of 0.92 m s-1. High MOV reduced stomatal pore length and aperture in plants developed at high RH. Moreover, stomatal function improved when high MOV-treated plants were subjected to leaflet desiccation and ABA feeding. Endogenous concentration of ABA and its metabolites in the leaves was reduced by 35% in high RH, but contrary to our hypothesis this concentration was not significantly affected by high MOV. Interestingly, in detached leaflets grown at high RH, high MOV increased stomatal sensitivity to ABA since the amount of exogenous ABA required to decrease the transpiration rate was significantly reduced. This is the first study to show that high MOV increases stomatal functionality in leaves developed at high RH by reducing the stomatal pore length and aperture and enhancing stomatal sensitivity to ABA rather than increasing leaf [ABA].

ABA-Mediated Stomatal Response in Regulating Water Use during the Development of Terminal Drought in Wheat

Directory of Open Access Journals (Sweden)

Renu Saradadevi

2017-07-01

Full Text Available End-of-season drought or “terminal drought,” which occurs after flowering, is considered the most significant abiotic stress affecting crop yields. Wheat crop production in Mediterranean-type environments is often exposed to terminal drought due to decreasing rainfall and rapid increases in temperature and evapotranspiration during spring when wheat crops enter the reproductive stage. Under such conditions, every millimeter of extra soil water extracted by the roots benefits grain filling and yield and improves water use efficiency (WUE. When terminal drought develops, soil dries from the top, exposing the top part of the root system to dry soil while the bottom part is in contact with available soil water. Plant roots sense the drying soil and produce signals, which on transmission to shoots trigger stomatal closure to regulate crop water use through transpiration. However, transpiration is linked to crop growth and productivity and limiting transpiration may reduce potential yield. While an early and high degree of stomatal closure affects photosynthesis and hence biomass production, a late and low degree of stomatal closure exhausts available soil water rapidly which results in yield losses through a reduction in post-anthesis water use. The plant hormone abscisic acid (ABA is considered the major chemical signal involved in stomatal regulation. Wheat genotypes differ in their ability to produce ABA under drought and also in their stomatal sensitivity to ABA. In this viewpoint article we discuss the possibilities of exploiting genotypic differences in ABA response to soil drying in regulating the use of water under terminal drought. Root density distribution in the upper drying layers of the soil profile is identified as a candidate trait that can affect ABA accumulation and subsequent stomatal closure. We also examine whether leaf ABA can be designated as a surrogate characteristic for improved WUE in wheat to sustain grain yield under

The Arabidopsis homolog of human G3BP1 is a key regulator of stomatal and apoplastic immunity

KAUST Repository

Abulfaraj, Aala A.; Mariappan, Kiruthiga; Bigeard, Jean; Manickam, Prabhu; Blilou, Ikram; Guo, Xiujie; Al-Babili, Salim; Pflieger, Delphine; Hirt, Heribert; Rayapuram, Naganand

2018-01-01

Mammalian Ras-GTPase–activating protein SH3-domain–binding proteins (G3BPs) are a highly conserved family of RNA-binding proteins that link kinase receptor-mediated signaling to RNA metabolism. Mammalian G3BP1 is a multifunctional protein that functions in viral immunity. Here, we show that the Arabidopsis thaliana homolog of human G3BP1 negatively regulates plant immunity. Arabidopsis g3bp1 mutants showed enhanced resistance to the virulent bacterial pathogen Pseudomonas syringae pv. tomato. Pathogen resistance was mediated in Atg3bp1 mutants by altered stomatal and apoplastic immunity. Atg3bp1 mutants restricted pathogen entry into stomates showing insensitivity to bacterial coronatine–mediated stomatal reopening. AtG3BP1 was identified as a negative regulator of defense responses, which correlated with moderate up-regulation of salicylic acid biosynthesis and signaling without growth penalty.

The Arabidopsis homolog of human G3BP1 is a key regulator of stomatal and apoplastic immunity

KAUST Repository

Abulfaraj, Aala Abdulaziz Hussien

2018-05-31

Mammalian Ras-GTPase–activating protein SH3-domain–binding proteins (G3BPs) are a highly conserved family of RNA-binding proteins that link kinase receptor-mediated signaling to RNA metabolism. Mammalian G3BP1 is a multifunctional protein that functions in viral immunity. Here, we show that the Arabidopsis thaliana homolog of human G3BP1 negatively regulates plant immunity. Arabidopsis g3bp1 mutants showed enhanced resistance to the virulent bacterial pathogen Pseudomonas syringae pv. tomato. Pathogen resistance was mediated in Atg3bp1 mutants by altered stomatal and apoplastic immunity. Atg3bp1 mutants restricted pathogen entry into stomates showing insensitivity to bacterial coronatine–mediated stomatal reopening. AtG3BP1 was identified as a negative regulator of defense responses, which correlated with moderate up-regulation of salicylic acid biosynthesis and signaling without growth penalty.

Compound stress response in stomatal closure: a mathematical model of ABA and ethylene interaction in guard cells

Directory of Open Access Journals (Sweden)

Beguerisse-Dıaz Mariano

2012-11-01

Full Text Available Abstract Background Stomata are tiny pores in plant leaves that regulate gas and water exchange between the plant and its environment. Abscisic acid and ethylene are two well-known elicitors of stomatal closure when acting independently. However, when stomata are presented with a combination of both signals, they fail to close. Results Toshed light on this unexplained behaviour, we have collected time course measurements of stomatal aperture and hydrogen peroxide production in Arabidopsis thaliana guard cells treated with abscisic acid, ethylene, and a combination of both. Our experiments show that stomatal closure is linked to sustained high levels of hydrogen peroxide in guard cells. When treated with a combined dose of abscisic acid and ethylene, guard cells exhibit increased antioxidant activity that reduces hydrogen peroxide levels and precludes closure. We construct a simplified model of stomatal closure derived from known biochemical pathways that captures the experimentally observed behaviour. Conclusions Our experiments and modelling results suggest a distinct role for two antioxidant mechanisms during stomatal closure: a slower, delayed response activated by a single stimulus (abscisic acid ‘or’ ethylene and another more rapid ‘and’ mechanism that is only activated when both stimuli are present. Our model indicates that the presence of this rapid ‘and’ mechanism in the antioxidant response is key to explain the lack of closure under a combined stimulus.

Guard cell photosynthesis is critical for stomatal turgor production, yet does not directly mediate CO2 - and ABA-induced stomatal closing.

Science.gov (United States)

Azoulay-Shemer, Tamar; Palomares, Axxell; Bagheri, Andisheh; Israelsson-Nordstrom, Maria; Engineer, Cawas B; Bargmann, Bastiaan O R; Stephan, Aaron B; Schroeder, Julian I

2015-08-01

Stomata mediate gas exchange between the inter-cellular spaces of leaves and the atmosphere. CO2 levels in leaves (Ci) are determined by respiration, photosynthesis, stomatal conductance and atmospheric [CO2 ]. [CO2 ] in leaves mediates stomatal movements. The role of guard cell photosynthesis in stomatal conductance responses is a matter of debate, and genetic approaches are needed. We have generated transgenic Arabidopsis plants that are chlorophyll-deficient in guard cells only, expressing a constitutively active chlorophyllase in a guard cell specific enhancer trap line. Our data show that more than 90% of guard cells were chlorophyll-deficient. Interestingly, approximately 45% of stomata had an unusual, previously not-described, morphology of thin-shaped chlorophyll-less stomata. Nevertheless, stomatal size, stomatal index, plant morphology, and whole-leaf photosynthetic parameters (PSII, qP, qN, FV '/FM' ) were comparable with wild-type plants. Time-resolved intact leaf gas-exchange analyses showed a reduction in stomatal conductance and CO2 -assimilation rates of the transgenic plants. Normalization of CO2 responses showed that stomata of transgenic plants respond to [CO2 ] shifts. Detailed stomatal aperture measurements of normal kidney-shaped stomata, which lack chlorophyll, showed stomatal closing responses to [CO2 ] elevation and abscisic acid (ABA), while thin-shaped stomata were continuously closed. Our present findings show that stomatal movement responses to [CO2 ] and ABA are functional in guard cells that lack chlorophyll. These data suggest that guard cell CO2 and ABA signal transduction are not directly modulated by guard cell photosynthesis/electron transport. Moreover, the finding that chlorophyll-less stomata cause a 'deflated' thin-shaped phenotype, suggests that photosynthesis in guard cells is critical for energization and guard cell turgor production. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

Acquired changes in stomatal characteristics in response to ozone during plant growth and leaf development of bush beans (Phaseolus vulgaris L.) indicate phenotypic plasticity

Energy Technology Data Exchange (ETDEWEB)

Elagoez, Vahram [Plant Biology Graduate Program, University of Massachusetts, Amherst, MA 01003 (United States)]. E-mail: velagoz@nsm.umass.edu; Han, Susan S. [Department of Plant, Soil and Insect Sciences, University of Massachusetts, Amherst, MA 01003 (United States); Manning, William J. [Department of Plant, Soil and Insect Sciences, University of Massachusetts, Amherst, MA 01003 (United States)

2006-04-15

Bush bean (Phaseolus vulgaris L.) lines 'S156' (O{sub 3}-sensitive)/'R123' (O{sub 3}-tolerant) and cultivars 'BBL 290' (O{sub 3}-sensitive)/'BBL 274' (O{sub 3}-tolerant) were used to study the effects of O{sub 3} on stomatal conductance (g {sub s}), density, and aperture size on leaf and pod surfaces with the objective of establishing links between the degree of plant sensitivity to O{sub 3} and plasticity of stomatal properties in response to O{sub 3}. Studies in open-top chambers (OTCs) and in continuously stirred tank reactors (CSTRs) established a clear relationship between plant developmental stages, degrees of O{sub 3} sensitivity and g {sub s}: while 'S156' had higher g {sub s} rates than 'R123' earlier in development, similar differences between 'BBL 290' and 'BBL 274' were observed at later stages. G {sub s} rates on the abaxial leaf surfaces of 'S156' and 'BBL 290', accompanied by low leaf temperatures, were significantly higher than their O{sub 3}-tolerant counterparts. Exposure to O{sub 3} in CSTRs had greater and more consistent impacts on both stomatal densities and aperture sizes of O{sub 3}-sensitive cultivars. Stomatal densities were highest on the abaxial leaf surfaces of 'S156' and 'BBL 290' at higher O{sub 3} concentrations (60 ppb), but the largest aperture sizes were recorded on the adaxial leaf surfaces at moderate O{sub 3} concentrations (30 ppb). Exposure to O{sub 3} eliminated aperture size differences on the adaxial leaf surfaces between sensitive and tolerant cultivars. Regardless of sensitivity to O{sub 3} and treatment regimes, the smallest aperture sizes and highest stomatal densities were found on the abaxial leaf surface. Our studies showed that O{sub 3} has the potential to affect stomatal plasticity and confirmed the presence of different control mechanisms for stomatal development on each leaf surface. This

Differential Effects of Phosphatidylinositol 4-Kinase (PI4K and 3-Kinase (PI3K Inhibitors on Stomatal Responses to Environmental Signals

Directory of Open Access Journals (Sweden)

Koh Iba

2017-05-01

Full Text Available Specific cellular components including products of phosphatidylinositol (PI metabolism play an important role as signaling molecules in stomatal responses to environmental signals. In this study, pharmacological inhibitors of a set of cellular components, including PI4-kinase (PI4K and PI3K, were used to investigate stomatal closure in response to CO2, darkness, and abscisic acid (ABA. Treatment with PAO, a specific inhibitor of PI4K, specifically inhibited the stomatal response to CO2 compared with that to darkness and ABA. In contrast, treatment with LY294002, a PI3K-specific inhibitor, specifically inhibited the stomatal response to darkness compared with that to CO2 and ABA. The specific inhibitory effects of PAO and LY294002 were also observed as changes in the spatial density of dot-like structures labeled by green fluorescent protein-tagged PATROL1, a protein that controls stomatal aperture possibly via regulation of H+-ATPase amount in guard cell plasma membranes. Our results suggest an important role for PI4K and PI3K in the CO2 and darkness signal transduction pathways, respectively, that mediate PATROL1 dynamics.

Stomatal kinetics and photosynthetic gas exchange along a continuum of isohydric to anisohydric regulation of plant water status

Science.gov (United States)

Frederick C. Meinzer; Duncan D. Smith; David R. Woodruff; Danielle E. Marias; Katherine A. McCulloh; Ava R. Howard; Alicia L. Magedman

2017-01-01

Species’ differences in the stringency of stomatal control of plant water potential represent a continuum of isohydric to anisohydric behaviours. However, little is known about how quasi-steady-state stomatal regulation of water potential may relate to dynamic behaviour of stomata and photosynthetic gas exchange in species operating at different positions along this...

Relating Stomatal Conductance to Leaf Functional Traits.

Science.gov (United States)

Kröber, Wenzel; Plath, Isa; Heklau, Heike; Bruelheide, Helge

2015-10-12

Leaf functional traits are important because they reflect physiological functions, such as transpiration and carbon assimilation. In particular, morphological leaf traits have the potential to summarize plants strategies in terms of water use efficiency, growth pattern and nutrient use. The leaf economics spectrum (LES) is a recognized framework in functional plant ecology and reflects a gradient of increasing specific leaf area (SLA), leaf nitrogen, phosphorus and cation content, and decreasing leaf dry matter content (LDMC) and carbon nitrogen ratio (CN). The LES describes different strategies ranging from that of short-lived leaves with high photosynthetic capacity per leaf mass to long-lived leaves with low mass-based carbon assimilation rates. However, traits that are not included in the LES might provide additional information on the species' physiology, such as those related to stomatal control. Protocols are presented for a wide range of leaf functional traits, including traits of the LES, but also traits that are independent of the LES. In particular, a new method is introduced that relates the plants' regulatory behavior in stomatal conductance to vapor pressure deficit. The resulting parameters of stomatal regulation can then be compared to the LES and other plant functional traits. The results show that functional leaf traits of the LES were also valid predictors for the parameters of stomatal regulation. For example, leaf carbon concentration was positively related to the vapor pressure deficit (vpd) at the point of inflection and the maximum of the conductance-vpd curve. However, traits that are not included in the LES added information in explaining parameters of stomatal control: the vpd at the point of inflection of the conductance-vpd curve was lower for species with higher stomatal density and higher stomatal index. Overall, stomata and vein traits were more powerful predictors for explaining stomatal regulation than traits used in the LES.

A CBL-Interacting Protein Kinase TaCIPK2 Confers Drought Tolerance in Transgenic Tobacco Plants through Regulating the Stomatal Movement.

Science.gov (United States)

Wang, Yan; Sun, Tao; Li, Tingting; Wang, Meng; Yang, Guangxiao; He, Guangyuan

2016-01-01

In plants, the CBL-CIPK signaling pathways play key roles in the response to abiotic stresses. However, functional studies of CIPKs in the important staple crop wheat are very rare. In this study, we identified a CIPK gene from wheat, designated TaCIPK2. Expression analysis results showed that TaCIPK2 could be up-regulated in wheat leaves by polyethylene glycol, abscisic acid and H2O2 treatments. Subcellular localization analyses revealed that TaCIPK2 was present in whole wheat epidermal cells. A yeast two-hybrid assay indicated that TaCIPK2 interacted with TaCBL1, 2, 3 and 4 in vitro. Transgenic tobacco plants over-expressing TaCIPK2 exhibited increased drought tolerance, indicated by a larger proportion of green cotyledons and higher survival rates under the osmotic and drought stress conditions compared with control plants. Additionally, physiological index analyses revealed that the transgenic tobacco plants had lower water loss rates and ion leakage, accumulated less malondialdehyde and H2O2, and had higher catalase and superoxide dismutase activities than the control plants. The transgenic plants also exhibited faster stomatal closure following exposure to osmotic stress conditions. The seed germination rates and stomatal aperture of TaCIPK2-overexpressing tobacco plants decreased after exogenous abscisic acid treatment was applied, implying that the transgenic tobacco plants were more sensitive to exogenous abscisic acid than the control plants. Our results indicate that TaCIPK2 plays a positive regulatory role in drought stress responses in transgenic tobacco plants.

Stomatal and Non-Stomatal Turbulent Deposition Flux of Ozone to a Managed Peatland

Directory of Open Access Journals (Sweden)

Tarek S. El-Madany

2017-09-01

Full Text Available Ozone is a key trace gas in the troposphere; because it is a greenhouse gas, it is very reactive, and it is potentially toxic to humans, fauna, and vegetation. The main sink processes for ozone are chemical reactions and the turbulent deposition flux to the earth’s surface. The deposition process itself is rather complex: The interactions between co-varying drivers such as the tropospheric ozone concentration, turbulence, and chemical reactions are not well understood. In the case of ozone deposition to vegetation, another aspect that must be studied is the role of stomatal regulation for a wide range of conditions. Therefore, we measured turbulent deposition fluxes of ozone with the eddy covariance technique during the peak of the growing season in 2014 over a managed, rewetted peatland in NW Germany. The deposition flux was large during the day (up to −15 nmol m−2 s−1 and relatively small during the night (between −1 and −2 nmol m−2 s−1. Flux partitioning by applying the surface resistance analogy and further analysis showed that the stomatal uptake was smaller than non-stomatal deposition. The correction of stomatal conductance with the gross primary production (GPP improved the estimation of day- and nighttime stomatal deposition fluxes. Statistical analysis confirmed that the friction velocity (u* was the single most important driver of non-stomatal ozone deposition and that relationships with other environmental drivers are not linear and highly variable. Further research is needed to develop a better process understanding of non-stomatal ozone deposition, to quantify the role of surface deposition to the ozone budget of the atmospheric boundary layer, and to estimate uncertainties associated with the partitioning of ozone deposition into stomatal and non-stomatal fluxes.

Does Size Matter? Atmospheric CO2 May Be a Stronger Driver of Stomatal Closing Rate Than Stomatal Size in Taxa That Diversified under Low CO2.

Science.gov (United States)

Elliott-Kingston, Caroline; Haworth, Matthew; Yearsley, Jon M; Batke, Sven P; Lawson, Tracy; McElwain, Jennifer C

2016-01-01

One strategy for plants to optimize stomatal function is to open and close their stomata quickly in response to environmental signals. It is generally assumed that small stomata can alter aperture faster than large stomata. We tested the hypothesis that species with small stomata close faster than species with larger stomata in response to darkness by comparing rate of stomatal closure across an evolutionary range of species including ferns, cycads, conifers, and angiosperms under controlled ambient conditions (380 ppm CO2; 20.9% O2). The two species with fastest half-closure time and the two species with slowest half-closure time had large stomata while the remaining three species had small stomata, implying that closing rate was not correlated with stomatal size in these species. Neither was response time correlated with stomatal density, phylogeny, functional group, or life strategy. Our results suggest that past atmospheric CO2 concentration during time of taxa diversification may influence stomatal response time. We show that species which last diversified under low or declining atmospheric CO2 concentration close stomata faster than species that last diversified in a high CO2 world. Low atmospheric [CO2] during taxa diversification may have placed a selection pressure on plants to accelerate stomatal closing to maintain adequate internal CO2 and optimize water use efficiency.

Analysis of Stomatal Patterning in Selected Mutants of MAPK Pathways

KAUST Repository

Felemban, Abrar

2016-05-01

Stomata are cellular valves in plants that play an essential role in the regulation of gas exchange and are distributed in the epidermis of aerial organs. In Arabidopsis thaliana, stomatal production and development are coordinated by the mitogen-activated protein kinase (MAPK) signalling pathway, which modulates a variety of other processes, including cell proliferation, regulation of cytokinesis, programed cell death, and response to abiotic and biotic stress. The environment also plays a role in stomatal development, by influencing the frequency at which stomata develop in leaves. This thesis presents an analysis of stomatal development in Arabidopsis mutants in two MAPK pathways: MEKK1-MKK1/MKK2-MPK4, and MAP3K17/18-MKK3. Obtained results demonstrate the effect of stress conditions on stomatal development and specify the involvement of analysed MAPK in stomatal patterning. First, both analysed pathways modulate stomatal patterning in Arabidopsis cotyledons. Second, plant growth-promoting bacteria tested enhance stomatal density and affect guard cell morphology. Third, the sucrose or mannitol treatment increases defects in stomatal patterning. Finally, salt stress or high temperature can suppress stomatal defects in mutants of the MEKK1-MKK1/MKK2-MPK4 pathway.

Ozone slows stomatal response to light and leaf wounding in a Mediterranean evergreen broadleaf, Arbutus unedo.

Science.gov (United States)

Paoletti, Elena

2005-04-01

The effect of a 90-d ozone exposure (charcoal-filtered air or 110 nmol mol(-1) O3) on stomatal conductance (gs) was investigated in the Mediterranean evergreen broadleaf Arbutus unedo L. Ozone did not significantly reduce midday steady-state gs compared to controls. However, it slowed stomatal response to abrupt reduction of light intensity and to increasing water stress, applied by severing the leaf midrib. Ozone slowed stomatal closure, rather than aperture. Nevertheless, vein-cutting did not allow ozonated leaves to reach the pre-injury gs levels, like controls did, suggesting re-opening was still, slowly in progress. The sluggish behaviour was recorded 10 days after cessation of O3 exposure ("memory effect") and may affect stomatal control in response to sunflecks and leaf wounding. Mediterranean evergreen broadleaves are regarded as tolerant to O3 exposure. Nevertheless, measurements of steady-state gs at midday may not account for altered stomatal responses to stressors.

Stomatal kinetics and photosynthetic gas exchange along a continuum of isohydric to anisohydric regulation of plant water status.

Science.gov (United States)

Meinzer, Frederick C; Smith, Duncan D; Woodruff, David R; Marias, Danielle E; McCulloh, Katherine A; Howard, Ava R; Magedman, Alicia L

2017-08-01

Species' differences in the stringency of stomatal control of plant water potential represent a continuum of isohydric to anisohydric behaviours. However, little is known about how quasi-steady-state stomatal regulation of water potential may relate to dynamic behaviour of stomata and photosynthetic gas exchange in species operating at different positions along this continuum. Here, we evaluated kinetics of light-induced stomatal opening, activation of photosynthesis and features of quasi-steady-state photosynthetic gas exchange in 10 woody species selected to represent different degrees of anisohydry. Based on a previously developed proxy for the degree of anisohydry, species' leaf water potentials at turgor loss, we found consistent trends in photosynthetic gas exchange traits across a spectrum of isohydry to anisohydry. More anisohydric species had faster kinetics of stomatal opening and activation of photosynthesis, and these kinetics were closely coordinated within species. Quasi-steady-state stomatal conductance and measures of photosynthetic capacity and performance were also greater in more anisohydric species. Intrinsic water-use efficiency estimated from leaf gas exchange and stable carbon isotope ratios was lowest in the most anisohydric species. In comparisons between gas exchange traits, species rankings were highly consistent, leading to species-independent scaling relationships over the range of isohydry to anisohydry observed. © 2017 John Wiley & Sons Ltd.

Ozone slows stomatal response to light and leaf wounding in a Mediterranean evergreen broadleaf, Arbutus unedo

Energy Technology Data Exchange (ETDEWEB)

Paoletti, Elena [Istituto Protezione Piante, Consiglio Nazionale delle Ricerche, Via Madonna del Piano, I-50019 Sesto Fiorentino (Italy)]. E-mail: e.paoletti@ipp.cnr.it

2005-04-01

The effect of a 90-d ozone exposure (charcoal-filtered air or 110 nmol mol{sup -1} O{sub 3}) on stomatal conductance (g{sub s}) was investigated in the Mediterranean evergreen broadleaf Arbutus unedo L. Ozone did not significantly reduce midday steady-state g{sub s} compared to controls. However, it slowed stomatal response to abrupt reduction of light intensity and to increasing water stress, applied by severing the leaf midrib. Ozone slowed stomatal closure, rather than aperture. Nevertheless, vein-cutting did not allow ozonated leaves to reach the pre-injury g{sub s} levels, like controls did, suggesting re-opening was still, slowly in progress. The sluggish behaviour was recorded 10 days after cessation of O{sub 3} exposure ('memory effect') and may affect stomatal control in response to sunflecks and leaf wounding. Mediterranean evergreen broadleaves are regarded as tolerant to O{sub 3} exposure. Nevertheless, measurements of steady-state g{sub s} at midday may not account for altered stomatal responses to stressors. - In response to ozone exposure, stomata were slower in closing rather than in opening.

Ozone slows stomatal response to light and leaf wounding in a Mediterranean evergreen broadleaf, Arbutus unedo

International Nuclear Information System (INIS)

Paoletti, Elena

2005-01-01

The effect of a 90-d ozone exposure (charcoal-filtered air or 110 nmol mol -1 O 3 ) on stomatal conductance (g s ) was investigated in the Mediterranean evergreen broadleaf Arbutus unedo L. Ozone did not significantly reduce midday steady-state g s compared to controls. However, it slowed stomatal response to abrupt reduction of light intensity and to increasing water stress, applied by severing the leaf midrib. Ozone slowed stomatal closure, rather than aperture. Nevertheless, vein-cutting did not allow ozonated leaves to reach the pre-injury g s levels, like controls did, suggesting re-opening was still, slowly in progress. The sluggish behaviour was recorded 10 days after cessation of O 3 exposure ('memory effect') and may affect stomatal control in response to sunflecks and leaf wounding. Mediterranean evergreen broadleaves are regarded as tolerant to O 3 exposure. Nevertheless, measurements of steady-state g s at midday may not account for altered stomatal responses to stressors. - In response to ozone exposure, stomata were slower in closing rather than in opening

Plant twitter: ligands under 140 amino acids enforcing stomatal patterning.

Science.gov (United States)

Rychel, Amanda L; Peterson, Kylee M; Torii, Keiko U

2010-05-01

Stomata are an essential land plant innovation whose patterning and density are under genetic and environmental control. Recently, several putative ligands have been discovered that influence stomatal density, and they all belong to the epidermal patterning factor-like family of secreted cysteine-rich peptides. Two of these putative ligands, EPF1 and EPF2, are expressed exclusively in the stomatal lineage cells and negatively regulate stomatal density. A third, EPFL6 or CHALLAH, is also a negative regulator of density, but is expressed subepidermally in the hypocotyl. A fourth, EPFL9 or STOMAGEN, is expressed in the mesophyll tissues and is a positive regulator of density. Genetic evidence suggests that these ligands may compete for the same receptor complex. Proper stomatal patterning is likely to be an intricate process involving ligand competition, regional specificity, and communication between tissue layers. EPFL-family genes exist in the moss Physcomitrella patens, the lycophyte Selaginella moellendorffii, and rice, Oryza sativa, and their sequence analysis yields several genes some of which are related to EPF1, EPF2, EPFL6, and EPFL9. Presence of these EPFL family members in the basal land plants suggests an exciting hypothesis that the genetic components for stomatal patterning originated early in land plant evolution.

Effects of stomatal development on stomatal conductance and on stomatal limitation of photosynthesis in Syringa oblata and Euonymus japonicus Thunb.

Science.gov (United States)

Wu, Bing-Jie; Chow, Wah Soon; Liu, Yu-Jun; Shi, Lei; Jiang, Chuang-Dao

2014-12-01

During leaf development, the increase in stomatal conductance cannot meet photosynthetic demand for CO2, thus leading to stomatal limitation of photosynthesis (Ls). Considering the crucial influences of stomatal development on stomatal conductance, we speculated whether stomatal development limits photosynthesis to some extent. To test this hypothesis, stomatal development, stomatal conductance and photosynthesis were carefully studied in both Syringa oblata (normal greening species) and Euonymus japonicus Thunb (delayed greening species). Our results show that the size of stomata increased gradually with leaf expansion, resulting in increased stomatal conductance up to the time of full leaf expansion. During this process, photosynthesis also increased steadily. Compared to that in S. oblata, the development of chloroplasts in E. japonicus Thunb was obviously delayed, leading to a delay in the improvement of photosynthetic capacity. Further analysis revealed that before full leaf expansion, stomatal limitation increased rapidly in both S. oblata and E. japonicus Thunb; after full leaf expansion, stomatal limitation continually increased in E. japonicus Thunb. Accordingly, we suggested that the enhancement of photosynthetic capacity is the main factor leading to stomatal limitation during leaf development but that stomatal development can alleviate stomatal limitation with the increase of photosynthesis by controlling gas exchange. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

The Arabidopsis guard cell outward potassium channel GORK is regulated by CPK33.

Science.gov (United States)

Corratgé-Faillie, Claire; Ronzier, Elsa; Sanchez, Frédéric; Prado, Karine; Kim, Jeong-Hyeon; Lanciano, Sophie; Leonhardt, Nathalie; Lacombe, Benoît; Xiong, Tou Cheu

2017-07-01

A complex signaling network involving voltage-gated potassium channels from the Shaker family contributes to the regulation of stomatal aperture. Several kinases and phosphatases have been shown to be crucial for ABA-dependent regulation of the ion transporters. To date, the Ca 2+ -dependent regulation of Shaker channels by Ca 2+ -dependent protein kinases (CPKs) is still elusive. A functional screen in Xenopus oocytes was launched to identify such CPKs able to regulate the three main guard cell Shaker channels KAT1, KAT2, and GORK. Seven guard cell CPKs were tested and multiple CPK/Shaker couples were identified. Further work on CPK33 indicates that GORK activity is enhanced by CPK33 and unaffected by a nonfunctional CPK33 (CPK33-K102M). Furthermore, Ca 2+ -induced stomatal closure is impaired in two cpk33 mutant plants. © 2017 Federation of European Biochemical Societies.

Mapping ‘hydroscapes’ along the iso- to anisohydric continuum of stomatal regulation of plant water status

Science.gov (United States)

Frederick C. Meinzer; David R. Woodruff; Danielle E. Marias; Duncan D. Smith; Katherine A. McCulloh; Ava R. Howard; Alicia L. Magedman; Josep Penuelas

2016-01-01

The concept of iso- vs. anisohydry has been used to describe the stringency of stomatal regulation of plant water potential (ψ). However, metrics that accurately and consistently quantify species’ operating ranges along a continuum of iso- to anisohydry have been elusive. Additionally, most approaches to quantifying iso/anisohydry require labour-intensive measurements...

Plant water potential improves prediction of empirical stomatal models.

Directory of Open Access Journals (Sweden)

William R L Anderegg

Full Text Available Climate change is expected to lead to increases in drought frequency and severity, with deleterious effects on many ecosystems. Stomatal responses to changing environmental conditions form the backbone of all ecosystem models, but are based on empirical relationships and are not well-tested during drought conditions. Here, we use a dataset of 34 woody plant species spanning global forest biomes to examine the effect of leaf water potential on stomatal conductance and test the predictive accuracy of three major stomatal models and a recently proposed model. We find that current leaf-level empirical models have consistent biases of over-prediction of stomatal conductance during dry conditions, particularly at low soil water potentials. Furthermore, the recently proposed stomatal conductance model yields increases in predictive capability compared to current models, and with particular improvement during drought conditions. Our results reveal that including stomatal sensitivity to declining water potential and consequent impairment of plant water transport will improve predictions during drought conditions and show that many biomes contain a diversity of plant stomatal strategies that range from risky to conservative stomatal regulation during water stress. Such improvements in stomatal simulation are greatly needed to help unravel and predict the response of ecosystems to future climate extremes.

Positive and negative peptide signals control stomatal density.

Science.gov (United States)

Shimada, Tomoo; Sugano, Shigeo S; Hara-Nishimura, Ikuko

2011-06-01

The stoma is a micro valve found on aerial plant organs that promotes gas exchange between the atmosphere and the plant body. Each stoma is formed by a strict cell lineage during the early stages of leaf development. Molecular genetics research using the model plant Arabidopsis has revealed the genes involved in stomatal differentiation. Cysteine-rich secretory peptides of the EPIDERMAL PATTERNING FACTOR-LIKE (EPFL) family play crucial roles as extracellular signaling factors. Stomatal development is orchestrated by the positive factor STOMAGEN/EPFL9 and the negative factors EPF1, EPF2, and CHALLAH/EPFL6 in combination with multiple receptors. EPF1 and EPF2 are produced in the stomatal lineage cells of the epidermis, whereas STOMAGEN and CHALLAH are derived from the inner tissues. These findings highlight the complex cell-to-cell and intertissue communications that regulate stomatal development. To optimize gas exchange, particularly the balance between the uptake of carbon dioxide (CO(2)) and loss of water, plants control stomatal activity in response to environmental conditions. The CO(2) level and light intensity influence stomatal density. Plants sense environmental cues in mature leaves and adjust the stomatal density of newly forming leaves, indicating the involvement of long-distance systemic signaling. This review summarizes recent research progress in the peptide signaling of stomatal development and discusses the evolutionary model of the signaling machinery.

Combining sap flow and eddy covariance approaches to derive stomatal and non-stomatal O3 fluxes in a forest stand

International Nuclear Information System (INIS)

Nunn, A.J.; Cieslik, S.; Metzger, U.; Wieser, G.; Matyssek, R.

2010-01-01

Stomatal O 3 fluxes to a mixed beech/spruce stand (Fagus sylvatica/Picea abies) in Central Europe were determined using two different approaches. The sap flow technique yielded the tree-level transpiration, whereas the eddy covariance method provided the stand-level evapotranspiration. Both data were then converted into stomatal ozone fluxes, exemplifying this novel concept for July 2007. Sap flow-based stomatal O 3 flux was 33% of the total O 3 flux, whereas derivation from evapotranspiration rates in combination with the Penman-Monteith algorithm amounted to 47%. In addition to this proportional difference, the sap flow-based assessment yielded lower levels of stomatal O 3 flux and reflected stomatal regulation rather than O 3 exposure, paralleling the daily courses of canopy conductance for water vapor and eddy covariance-based total stand-level O 3 flux. The demonstrated combination of sap flow and eddy covariance approaches supports the development of O 3 risk assessment in forests from O 3 exposure towards flux-based concepts. - Combined tree sap flow and eddy covariance-based methodologies yield stomatal O 3 flux as 33% in total stand flux.

Quantitative Evaluation of Stomatal Cytoskeletal Patterns during the Activation of Immune Signaling in Arabidopsis thaliana.

Directory of Open Access Journals (Sweden)

Masaki Shimono

Full Text Available Historically viewed as primarily functioning in the regulation of gas and water vapor exchange, it is now evident that stomata serve an important role in plant immunity. Indeed, in addition to classically defined functions related to cell architecture and movement, the actin cytoskeleton has emerged as a central component of the plant immune system, underpinning not only processes related to cell shape and movement, but also receptor activation and signaling. Using high resolution quantitative imaging techniques, the temporal and spatial changes in the actin microfilament array during diurnal cycling of stomatal guard cells has revealed a highly orchestrated transition from random arrays to ordered bundled filaments. While recent studies have demonstrated that plant stomata close in response to pathogen infection, an evaluation of stimulus-induced changes in actin cytoskeletal dynamics during immune activation in the guard cell, as well as the relationship of these changes to the function of the actin cytoskeleton and stomatal aperture, remains undefined. In the current study, we employed quantitative cell imaging and hierarchical clustering analyses to define the response of the guard cell actin cytoskeleton to pathogen infection and the elicitation of immune signaling. Using this approach, we demonstrate that stomatal-localized actin filaments respond rapidly, and specifically, to both bacterial phytopathogens and purified pathogen elicitors. Notably, we demonstrate that higher order temporal and spatial changes in the filament array show distinct patterns of organization during immune activation, and that changes in the naïve diurnal oscillations of guard cell actin filaments are perturbed by pathogens, and that these changes parallel pathogen-induced stomatal gating. The data presented herein demonstrate the application of a highly tractable and quantifiable method to assign transitions in actin filament organization to the activation of

Drought responses of two gymnosperm species with contrasting stomatal regulation strategies under elevated [CO2] and temperature.

Science.gov (United States)

Duan, Honglang; O'Grady, Anthony P; Duursma, Remko A; Choat, Brendan; Huang, Guomin; Smith, Renee A; Jiang, Yanan; Tissue, David T

2015-07-01

Future climate regimes characterized by rising [CO2], rising temperatures and associated droughts may differentially affect tree growth and physiology. However, the interactive effects of these three factors are complex because elevated [CO2] and elevated temperature may generate differential physiological responses during drought. To date, the interactive effects of elevated [CO2] and elevated temperature on drought-induced tree mortality remain poorly understood in gymnosperm species that differ in stomatal regulation strategies. Water relations and carbon dynamics were examined in two species with contrasting stomatal regulation strategies: Pinus radiata D. Don (relatively isohydric gymnosperm; regulating stomata to maintain leaf water potential above critical thresholds) and Callitris rhomboidea R. Br (relatively anisohydric gymnosperm; allowing leaf water potential to decline as the soil dries), to assess response to drought as a function of [CO2] and temperature. Both species were grown in two [CO2] (C(a) (ambient, 400 μl l(-1)) and C(e) (elevated, 640 μl l(-1))) and two temperature (T(a) (ambient) and T(e) (ambient +4 °C)) treatments in a sun-lit glasshouse under well-watered conditions. Drought plants were then exposed to a progressive drought until mortality. Prior to mortality, extensive xylem cavitation occurred in both species, but significant depletion of non-structural carbohydrates was not observed in either species. Te resulted in faster mortality in P. radiata, but it did not modify the time-to-mortality in C. rhomboidea. C(e) did not delay the time-to-mortality in either species under drought or T(e) treatments. In summary, elevated temperature (+4 °C) had greater influence than elevated [CO2] (+240 μl l(-1)) on drought responses of the two studied gymnosperm species, while stomatal regulation strategies did not generally affect the relative contributions of hydraulic failure and carbohydrate depletion to mortality under severe drought. �

Functional Analysis of Cellulose and Xyloglucan in the Walls of Stomatal Guard Cells of Arabidopsis1[OPEN

Science.gov (United States)

Rui, Yue; Anderson, Charles T.

2016-01-01

Stomatal guard cells are pairs of specialized epidermal cells that control water and CO2 exchange between the plant and the environment. To fulfill the functions of stomatal opening and closure that are driven by changes in turgor pressure, guard cell walls must be both strong and flexible, but how the structure and dynamics of guard cell walls enable stomatal function remains poorly understood. To address this question, we applied cell biological and genetic analyses to investigate guard cell walls and their relationship to stomatal function in Arabidopsis (Arabidopsis thaliana). Using live-cell spinning disk confocal microscopy, we measured the motility of cellulose synthase (CESA)-containing complexes labeled by green fluorescent protein (GFP)-CESA3 and observed a reduced proportion of GFP-CESA3 particles colocalizing with microtubules upon stomatal closure. Imaging cellulose organization in guard cells revealed a relatively uniform distribution of cellulose in the open state and a more fibrillar pattern in the closed state, indicating that cellulose microfibrils undergo dynamic reorganization during stomatal movements. In cesa3je5 mutants defective in cellulose synthesis and xxt1 xxt2 mutants lacking the hemicellulose xyloglucan, stomatal apertures, changes in guard cell length, and cellulose reorganization were aberrant during fusicoccin-induced stomatal opening or abscisic acid-induced stomatal closure, indicating that sufficient cellulose and xyloglucan are required for normal guard cell dynamics. Together, these results provide new insights into how guard cell walls allow stomata to function as responsive mediators of gas exchange at the plant surface. PMID:26729799

ABA-Induced Stomatal Closure Involves ALMT4, a Phosphorylation-Dependent Vacuolar Anion Channel of Arabidopsis[OPEN

Science.gov (United States)

Baetz, Ulrike; Huck, Nicola V.; Zhang, Jingbo

2017-01-01

Stomatal pores are formed between a pair of guard cells and allow plant uptake of CO2 and water evaporation. Their aperture depends on changes in osmolyte concentration of guard cell vacuoles, specifically of K+ and Mal2−. Efflux of Mal2− from the vacuole is required for stomatal closure; however, it is not clear how the anion is released. Here, we report the identification of ALMT4 (ALUMINUM ACTIVATED MALATE TRANSPORTER4) as an Arabidopsis thaliana ion channel that can mediate Mal2− release from the vacuole and is required for stomatal closure in response to abscisic acid (ABA). Knockout mutants showed impaired stomatal closure in response to the drought stress hormone ABA and increased whole-plant wilting in response to drought and ABA. Electrophysiological data show that ALMT4 can mediate Mal2− efflux and that the channel activity is dependent on a phosphorylatable C-terminal serine. Dephosphomimetic mutants of ALMT4 S382 showed increased channel activity and Mal2− efflux. Reconstituting the active channel in almt4 mutants impaired growth and stomatal opening. Phosphomimetic mutants were electrically inactive and phenocopied the almt4 mutants. Surprisingly, S382 can be phosphorylated by mitogen-activated protein kinases in vitro. In brief, ALMT4 likely mediates Mal2− efflux during ABA-induced stomatal closure and its activity depends on phosphorylation. PMID:28874508

CDPKs CPK6 and CPK3 function in ABA regulation of guard cell S-type anion- and Ca(2+-permeable channels and stomatal closure.

Directory of Open Access Journals (Sweden)

Izumi C Mori

2006-10-01

Full Text Available Abscisic acid (ABA signal transduction has been proposed to utilize cytosolic Ca(2+ in guard cell ion channel regulation. However, genetic mutants in Ca(2+ sensors that impair guard cell or plant ion channel signaling responses have not been identified, and whether Ca(2+-independent ABA signaling mechanisms suffice for a full response remains unclear. Calcium-dependent protein kinases (CDPKs have been proposed to contribute to central signal transduction responses in plants. However, no Arabidopsis CDPK gene disruption mutant phenotype has been reported to date, likely due to overlapping redundancies in CDPKs. Two Arabidopsis guard cell-expressed CDPK genes, CPK3 and CPK6, showed gene disruption phenotypes. ABA and Ca(2+ activation of slow-type anion channels and, interestingly, ABA activation of plasma membrane Ca(2+-permeable channels were impaired in independent alleles of single and double cpk3cpk6 mutant guard cells. Furthermore, ABA- and Ca(2+-induced stomatal closing were partially impaired in these cpk3cpk6 mutant alleles. However, rapid-type anion channel current activity was not affected, consistent with the partial stomatal closing response in double mutants via a proposed branched signaling network. Imposed Ca(2+ oscillation experiments revealed that Ca(2+-reactive stomatal closure was reduced in CDPK double mutant plants. However, long-lasting Ca(2+-programmed stomatal closure was not impaired, providing genetic evidence for a functional separation of these two modes of Ca(2+-induced stomatal closing. Our findings show important functions of the CPK6 and CPK3 CDPKs in guard cell ion channel regulation and provide genetic evidence for calcium sensors that transduce stomatal ABA signaling.

Adaxial/abaxial specification in the regulation of photosynthesis and stomatal opening with respect to light orientation and growth with CO2 enrichment in the C4 species Paspalum dilatatum.

Science.gov (United States)

Soares, Ana Sofia; Driscoll, Simon P; Olmos, Enrique; Harbinson, Jeremy; Arrabaça, Maria Celeste; Foyer, Christine H

2008-01-01

Whole-plant morphology, leaf structure and composition were studied together with the effects of light orientation on the dorso-ventral regulation of photosynthesis and stomatal conductance in Paspalum dilatatum cv. Raki plants grown for 6 wk at either 350 or 700 microl l(-1) CO(2). Plant biomass was doubled as a result of growth at high CO(2) and the shoot:root ratio was decreased. Stomatal density was increased in the leaves of the high CO(2)-grown plants, which had greater numbers of smaller stomata and more epidermal cells on the abaxial surface. An asymmetric surface-specific regulation of photosynthesis and stomatal conductance was observed with respect to light orientation. This was not caused by dorso-ventral variations in leaf structure, the distribution of phosphoenolpyruvate carboxylase (PEPC) and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) proteins or light absorptance, transmittance or reflectance. Adaxial/abaxial specification in the regulation of photosynthesis results from differential sensitivity of stomatal opening to light orientation and fixed gradients of enzyme activation across the leaf.

Atmospheric CO2 Alters Resistance of Arabidopsis to Pseudomonas syringae by Affecting Abscisic Acid Accumulation and Stomatal Responsiveness to Coronatine

NARCIS (Netherlands)

Zhou, Y.; Vroegop-Vos, I.; Schuurink, R.C.; Pieterse, C.M.J.; Van Wees, S.C.M.

Atmospheric CO2 influences plant growth and stomatal aperture. Effects of high or low CO2 levels on plant disease resistance are less well understood. Here, resistance of Arabidopsis thaliana against the foliar pathogen Pseudomonas syringae pv. tomato DC3000 (Pst) was investigated at three different

A fast method to detect the occurrence of nonhomogeneous distribution of stomatal aperture in heterobaric plant leaves : Experiments with Arbutus unedo L. during the diurnal course.

Science.gov (United States)

Beyschlag, W; Pfanz, H

1990-01-01

Pressure infiltration of water into a leaf via the stomatal pores can be used to quickly determine whether all stomata are open, or as recently described for several mesophytic and xerophytic species, whether there is a non-homogeneous distribution of stomatal opening (stomatal patchiness) on the leaf surface. Information about this phenomenon is important since the commonly used algorithms for calculation of leaf conductance from water vapor exchange measurements imply homogeneously open stomata, which in the occurrence of stomatal patchiness will lead to erroneous results. Infiltration experiments in a growth chamber with leaves of the Mediterranean evergreen shrub Arbutus unedo, carried out under simulated Mediterranean summer day conditions, where the species typically exhibits a strong midday stomatal closure, revealed a temporary occurrence of stomatal patchiness during the phase of stomatal closure in the late morning and during the stomatal reopening in the afternoon. Leaves were, however, found to be fully (i.e. homogeneously) infiltratable in the morning and in the evening. At midday during maximum stomatal closure, leaves were almost non-infiltratable. During the day, the infiltrated amount of water was found to be linearly correlated with porometer measurements of leaf conductance of the same leaves, carried out with the attached leaves immediately before infiltration.

Mix-and-match: ligand-receptor pairs in stomatal development and beyond.

Science.gov (United States)

Torii, Keiko U

2012-12-01

Stomata are small valves on the plant epidermis balancing gas exchange and water loss. Stomata are formed according to positional cues. In Arabidopsis, two EPIDERMAL PATTERNING FACTOR (EPF) peptides, EPF1 and EPF2, are secreted from stomatal precursors enforcing proper stomatal patterning. Here, I review recent studies revealing the ligand-receptor pairs and revising the previously predicted relations between receptors specifying stomatal patterning: ERECTA-family and TOO MANY MOUTHS (TMM). Furthermore, EPF-LIKE9 (EPFL9/Stomagen) promotes stomatal differentiation from internal tissues. Two EPFL peptides specify inflorescence architecture, a process beyond stomatal development, as ligands for ERECTA. Thus, broadly expressed receptor kinases may regulate multiple developmental processes through perceiving different peptide ligands, each with a specialized expression pattern. TMM in the epidermis may fine-tune multiple EPF/EPFL signals to prevent signal interference. Copyright © 2012 Elsevier Ltd. All rights reserved.

Organ-specific effects of brassinosteroids on stomatal production coordinate with the action of Too Many Mouths.

Science.gov (United States)

Wang, Ming; Yang, Kezhen; Le, Jie

2015-03-01

In Arabidopsis, stomatal development initiates after protodermal cells acquire stomatal lineage cell fate. Stomata or their precursors communicate with their neighbor epidermal cells to ensure the "one cell spacing" rule. The signals from EPF/EPFL peptide ligands received by Too Many Mouths (TMM) and ERECTA-family receptors are supposed to be transduced by YODA MAPK cascade. A basic helix-loop-helix transcription factor SPEECHLESS (SPCH) is another key regulator of stomatal cell fate determination and asymmetric entry divisions, and SPCH activity is regulated by YODA MAPK cascade. Brassinosteroid (BR) signaling, one of the most well characterized signal transduction pathways in plants, contributes to the control of stomatal production. But opposite organ-specific effects of BR on stomatal production were reported. Here we confirm that stomatal production in hypocotyls is controlled by BR levels. YODA and CYCD4 are not essential for BR stomata-promoting function. Furthermore, we found that BR could confer tmm hypocotyls clustered stomatal phenotype, indicating that the BR organ-specific effects on stomatal production might coordinate with the TMM organ-specific actions. © 2014 Institute of Botany, Chinese Academy of Sciences.

Stomatal behavior in fruits and leaves of the purple passion fruit (Passiflora edulis Sims and fruits and cladodes of the yellow pitaya [Hylocereus megalanthus (K. Schum. ex Vaupel Ralf Bauer

Directory of Open Access Journals (Sweden)

Camilo Sánchez

2013-04-01

Full Text Available Plants as C3 and CAM react photosynthetically different but both can grow in the same agroecological zone in the tropics. Therefore we studied the behavior of stomatal opening in fruits and leaves of the purple passion fruit and fruits and cladodes of the yellow pitaya was studied under natural growing conditions in Granada and Fusagasuga, Cundinamarca (Colombia. Imprints were made on the surface of leaves, fruits and cladodes using cosmetic enamel impressions. Three cycles were carried out, each cycle took 72 hours, obtaining three different samples every 3 hours; then the impressions were observed by microscope and the opened and closed stomata were counted in each species. In each sampling, data of solar radiation, temperature and relative humidity (RH were measured. The purple passion fruit had the typical behavior of a C3 plant in the leaves as well as the fruits, and a positive correlation between the stomatal aperture and radiation and temperature was found, along with a negative correlation between stomatal aperture and RH. The pitaya showed the typical behavior of a CAM plant with a negative correlation between the stomatal opening and radiation and temperature, as well as a positive correlation between stomatal opening and RH. Radiation, temperature and RH affected the stomatal opening in the fruits and cladodes. Stomatal densities differed greatly between the species and plant organs. In the purple passion fruit, 106.53 stomata per mm² leaf surface were found, but only 12.64 stomata per mm² fruit surface; whereas in the pitaya, 11.28 and 1.43 stomata per mm² were found on the cladodes and fruits, respectively

Overexpression of plasma membrane H+-ATPase in guard cells promotes light-induced stomatal opening and enhances plant growth.

Science.gov (United States)

Wang, Yin; Noguchi, Ko; Ono, Natsuko; Inoue, Shin-ichiro; Terashima, Ichiro; Kinoshita, Toshinori

2014-01-07

Stomatal pores surrounded by a pair of guard cells in the plant epidermis control gas exchange between plants and the atmosphere in response to light, CO2, and the plant hormone abscisic acid. Light-induced stomatal opening is mediated by at least three key components: the blue light receptor phototropin (phot1 and phot2), plasma membrane H(+)-ATPase, and plasma membrane inward-rectifying K(+) channels. Very few attempts have been made to enhance stomatal opening with the goal of increasing photosynthesis and plant growth, even though stomatal resistance is thought to be the major limiting factor for CO2 uptake by plants. Here, we show that transgenic Arabidopsis plants overexpressing H(+)-ATPase using the strong guard cell promoter GC1 showed enhanced light-induced stomatal opening, photosynthesis, and plant growth. The transgenic plants produced larger and increased numbers of rosette leaves, with ∼42-63% greater fresh and dry weights than the wild type in the first 25 d of growth. The dry weights of total flowering stems of 45-d-old transgenic plants, including seeds, siliques, and flowers, were ∼36-41% greater than those of the wild type. In addition, stomata in the transgenic plants closed normally in response to darkness and abscisic acid. In contrast, the overexpression of phototropin or inward-rectifying K(+) channels in guard cells had no effect on these phenotypes. These results demonstrate that stomatal aperture is a limiting factor in photosynthesis and plant growth, and that manipulation of stomatal opening by overexpressing H(+)-ATPase in guard cells is useful for the promotion of plant growth.

Common and unique elements of the ABA-regulated transcriptome of Arabidopsis guard cells

Directory of Open Access Journals (Sweden)

Zhao Zhixin

2011-05-01

Full Text Available Abstract Background In the presence of drought and other desiccating stresses, plants synthesize and redistribute the phytohormone abscisic acid (ABA. ABA promotes plant water conservation by acting on specialized cells in the leaf epidermis, guard cells, which border and regulate the apertures of stomatal pores through which transpirational water loss occurs. Following ABA exposure, solute uptake into guard cells is rapidly inhibited and solute loss is promoted, resulting in inhibition of stomatal opening and promotion of stomatal closure, with consequent plant water conservation. There is a wealth of information on the guard cell signaling mechanisms underlying these rapid ABA responses. To investigate ABA regulation of gene expression in guard cells in a systematic genome-wide manner, we analyzed data from global transcriptomes of guard cells generated with Affymetrix ATH1 microarrays, and compared these results to ABA regulation of gene expression in leaves and other tissues. Results The 1173 ABA-regulated genes of guard cells identified by our study share significant overlap with ABA-regulated genes of other tissues, and are associated with well-defined ABA-related promoter motifs such as ABREs and DREs. However, we also computationally identified a unique cis-acting motif, GTCGG, associated with ABA-induction of gene expression specifically in guard cells. In addition, approximately 300 genes showing ABA-regulation unique to this cell type were newly uncovered by our study. Within the ABA-regulated gene set of guard cells, we found that many of the genes known to encode ion transporters associated with stomatal opening are down-regulated by ABA, providing one mechanism for long-term maintenance of stomatal closure during drought. We also found examples of both negative and positive feedback in the transcriptional regulation by ABA of known ABA-signaling genes, particularly with regard to the PYR/PYL/RCAR class of soluble ABA receptors and

Common and unique elements of the ABA-regulated transcriptome of Arabidopsis guard cells

Science.gov (United States)

2011-01-01

Background In the presence of drought and other desiccating stresses, plants synthesize and redistribute the phytohormone abscisic acid (ABA). ABA promotes plant water conservation by acting on specialized cells in the leaf epidermis, guard cells, which border and regulate the apertures of stomatal pores through which transpirational water loss occurs. Following ABA exposure, solute uptake into guard cells is rapidly inhibited and solute loss is promoted, resulting in inhibition of stomatal opening and promotion of stomatal closure, with consequent plant water conservation. There is a wealth of information on the guard cell signaling mechanisms underlying these rapid ABA responses. To investigate ABA regulation of gene expression in guard cells in a systematic genome-wide manner, we analyzed data from global transcriptomes of guard cells generated with Affymetrix ATH1 microarrays, and compared these results to ABA regulation of gene expression in leaves and other tissues. Results The 1173 ABA-regulated genes of guard cells identified by our study share significant overlap with ABA-regulated genes of other tissues, and are associated with well-defined ABA-related promoter motifs such as ABREs and DREs. However, we also computationally identified a unique cis-acting motif, GTCGG, associated with ABA-induction of gene expression specifically in guard cells. In addition, approximately 300 genes showing ABA-regulation unique to this cell type were newly uncovered by our study. Within the ABA-regulated gene set of guard cells, we found that many of the genes known to encode ion transporters associated with stomatal opening are down-regulated by ABA, providing one mechanism for long-term maintenance of stomatal closure during drought. We also found examples of both negative and positive feedback in the transcriptional regulation by ABA of known ABA-signaling genes, particularly with regard to the PYR/PYL/RCAR class of soluble ABA receptors and their downstream targets

Fern Stomatal Responses to ABA and CO2 Depend on Species and Growth Conditions.

Science.gov (United States)

Hõrak, Hanna; Kollist, Hannes; Merilo, Ebe

2017-06-01

Changing atmospheric CO 2 levels, climate, and air humidity affect plant gas exchange that is controlled by stomata, small pores on plant leaves and stems formed by guard cells. Evolution has shaped the morphology and regulatory mechanisms governing stomatal movements to correspond to the needs of various land plant groups over the past 400 million years. Stomata close in response to the plant hormone abscisic acid (ABA), elevated CO 2 concentration, and reduced air humidity. Whether the active regulatory mechanisms that control stomatal closure in response to these stimuli are present already in mosses, the oldest plant group with stomata, or were acquired more recently in angiosperms remains controversial. It has been suggested that the stomata of the basal vascular plants, such as ferns and lycophytes, close solely hydropassively. On the other hand, active stomatal closure in response to ABA and CO 2 was found in several moss, lycophyte, and fern species. Here, we show that the stomata of two temperate fern species respond to ABA and CO 2 and that an active mechanism of stomatal regulation in response to reduced air humidity is present in some ferns. Importantly, fern stomatal responses depend on growth conditions. The data indicate that the stomatal behavior of ferns is more complex than anticipated before, and active stomatal regulation is present in some ferns and has possibly been lost in others. Further analysis that takes into account fern species, life history, evolutionary age, and growth conditions is required to gain insight into the evolution of land plant stomatal responses. © 2017 American Society of Plant Biologists. All Rights Reserved.

Impaired Malate and Fumarate Accumulation Due to the Mutation of the Tonoplast Dicarboxylate Transporter Has Little Effects on Stomatal Behavior.

Science.gov (United States)

Medeiros, David B; Barros, Kallyne A; Barros, Jessica Aline S; Omena-Garcia, Rebeca P; Arrivault, Stéphanie; Sanglard, Lílian M V P; Detmann, Kelly C; Silva, Willian Batista; Daloso, Danilo M; DaMatta, Fábio M; Nunes-Nesi, Adriano; Fernie, Alisdair R; Araújo, Wagner L

2017-11-01

Malate is a central metabolite involved in a multiplicity of plant metabolic pathways, being associated with mitochondrial metabolism and playing significant roles in stomatal movements. Vacuolar malate transport has been characterized at the molecular level and is performed by at least one carrier protein and two channels in Arabidopsis ( Arabidopsis thaliana ) vacuoles. The absence of the Arabidopsis tonoplast Dicarboxylate Transporter (tDT) in the tdt knockout mutant was associated previously with an impaired accumulation of malate and fumarate in leaves. Here, we investigated the consequences of this lower accumulation on stomatal behavior and photosynthetic capacity as well as its putative metabolic impacts. Neither the stomatal conductance nor the kinetic responses to dark, light, or high CO 2 were highly affected in tdt plants. In addition, we did not observe any impact on stomatal aperture following incubation with abscisic acid, malate, or citrate. Furthermore, an effect on photosynthetic capacity was not observed in the mutant lines. However, leaf mitochondrial metabolism was affected in the tdt plants. Levels of the intermediates of the tricarboxylic acid cycle were altered, and increases in both light and dark respiration were observed. We conclude that manipulation of the tonoplastic organic acid transporter impacted mitochondrial metabolism, while the overall stomatal and photosynthetic capacity were unaffected. © 2017 American Society of Plant Biologists. All Rights Reserved.

The Arabidopsis lectin receptor kinase LecRK-V.5 represses stomatal immunity induced by Pseudomonas syringae pv. tomato DC3000.

Directory of Open Access Journals (Sweden)

Marie Desclos-Theveniau

2012-02-01

Full Text Available Stomata play an important role in plant innate immunity by limiting pathogen entry into leaves but molecular mechanisms regulating stomatal closure upon pathogen perception are not well understood. Here we show that the Arabidopsis thaliana L-type lectin receptor kinase-V.5 (LecRK-V.5 negatively regulates stomatal immunity. Loss of LecRK-V.5 function increased resistance to surface inoculation with virulent bacteria Pseudomonas syringae pv tomato DC3000. Levels of resistance were not affected after infiltration-inoculation, suggesting that LecRK-V.5 functions at an early defense stage. By contrast, lines overexpressing LecRK-V.5 were more susceptible to Pst DC3000. Enhanced resistance in lecrk-V.5 mutants was correlated with constitutive stomatal closure, while increased susceptibility phenotypes in overexpression lines were associated with early stomatal reopening. Lines overexpressing LecRK-V.5 also demonstrated a defective stomatal closure after pathogen-associated molecular pattern (PAMP treatments. LecRK-V.5 is rapidly expressed in stomatal guard cells after bacterial inoculation or treatment with the bacterial PAMP flagellin. In addition, lecrk-V.5 mutants guard cells exhibited constitutive accumulation of reactive oxygen species (ROS and inhibition of ROS production opened stomata of lecrk-V.5. LecRK-V.5 is also shown to interfere with abscisic acid-mediated stomatal closure signaling upstream of ROS production. These results provide genetic evidences that LecRK-V.5 negatively regulates stomatal immunity upstream of ROS biosynthesis. Our data reveal that plants have evolved mechanisms to reverse bacteria-mediated stomatal closure to prevent long-term effect on CO(2 uptake and photosynthesis.

A rate equation model of stomatal responses to vapour pressure deficit and drought

Directory of Open Access Journals (Sweden)

Shanahan ST

2002-08-01

Full Text Available Abstract Background Stomata respond to vapour pressure deficit (D – when D increases, stomata begin to close. Closure is the result of a decline in guard cell turgor, but the link between D and turgor is poorly understood. We describe a model for stomatal responses to increasing D based upon cellular water relations. The model also incorporates impacts of increasing levels of water stress upon stomatal responses to increasing D. Results The model successfully mimics the three phases of stomatal responses to D and also reproduces the impact of increasing plant water deficit upon stomatal responses to increasing D. As water stress developed, stomata regulated transpiration at ever decreasing values of D. Thus, stomatal sensitivity to D increased with increasing water stress. Predictions from the model concerning the impact of changes in cuticular transpiration upon stomatal responses to increasing D are shown to conform to experimental data. Sensitivity analyses of stomatal responses to various parameters of the model show that leaf thickness, the fraction of leaf volume that is air-space, and the fraction of mesophyll cell wall in contact with air have little impact upon behaviour of the model. In contrast, changes in cuticular conductance and membrane hydraulic conductivity have significant impacts upon model behaviour. Conclusion Cuticular transpiration is an important feature of stomatal responses to D and is the cause of the 3 phase response to D. Feed-forward behaviour of stomata does not explain stomatal responses to D as feedback, involving water loss from guard cells, can explain these responses.

Analysis of Stomatal Patterning in Selected Mutants of MAPK Pathways

KAUST Repository

Felemban, Abrar

2016-01-01

-activated protein kinase (MAPK) signalling pathway, which modulates a variety of other processes, including cell proliferation, regulation of cytokinesis, programed cell death, and response to abiotic and biotic stress. The environment also plays a role in stomatal

Stomatal structure and physiology do not explain differences in water use among montane eucalypts.

Science.gov (United States)

Gharun, Mana; Turnbull, Tarryn L; Pfautsch, Sebastian; Adams, Mark A

2015-04-01

Understanding the regulation of water use at the whole-tree scale is critical to advancing the utility of physiological ecology, for example in its role in predictive hydrology of forested catchments. For three eucalypt species that dominate high-elevation catchments in south-eastern Australia, we examined if whole-tree water use could be related to three widely discussed regulators of water use: stomatal anatomy, sensitivity of stomata [i.e. stomatal conductance (g(s))] to environmental influences, and sapwood area. While daily tree water use varied sixfold among species, sap velocity and sapwood area varied in parallel. Combined, stomatal structure and physiology could not explain differences in species-specific water use. Species which exhibited the fastest (Eucalyptus delegatensis) and slowest (Eucalyptus pauciflora) rates of water use both exhibited greater capacity for physiological control of g(s) [indicated by sensitivity to vapour pressure deficit (VPD)] and a reduced capacity to limit g(s) anatomically [indicated by greater potential g(s) (g(max))]. Conversely, g(s) was insensitive to VPD and g(max) was lowest for Eucalyptus radiata, the species showing intermediate rates of water use. Improved knowledge of stomatal anatomy will help us to understand the capacity of species to regulate leaf-level water loss, but seems likely to remain of limited use for explaining rates of whole-tree water use in montane eucalypts at the catchment scale.

Transcription co-activator Arabidopsis ANGUSTIFOLIA3 (AN3) regulates water-use efficiency and drought tolerance by modulating stomatal density and improving root architecture by the transrepression of YODA (YDA).

Science.gov (United States)

Meng, Lai-Sheng; Yao, Shun-Qiao

2015-09-01

One goal of modern agriculture is the improvement of plant drought tolerance and water-use efficiency (WUE). Although stomatal density has been linked to WUE, the causal molecular mechanisms and engineered alternations of this relationship are not yet fully understood. Moreover, YODA (YDA), which is a MAPKK kinase gene, negatively regulates stomatal development. BR-INSENSITIVE 2 interacts with phosphorylates and inhibits YDA. However, whether YDA is modulated in the transcriptional level is still unclear. Plants lacking ANGUSTIFOLIA3 (AN3) activity have high drought stress tolerance because of low stomatal densities and improved root architecture. Such plants also exhibit enhanced WUE through declining transpiration without a demonstrable reduction in biomass accumulation. AN3 negatively regulated YDA expression at the transcriptional level by target-gene analysis. Chromatin immunoprecipitation analysis indicated that AN3 was associated with a region of the YDA promoter in vivo. YDA mutation significantly decreased the stomatal density and root length of an3 mutant, thus proving the participation of YDA in an3 drought tolerance and WUE enhancement. These components form an AN3-YDA complex, which allows the integration of water deficit stress signalling into the production or spacing of stomata and cell proliferation, thus leading to drought tolerance and enhanced WUE. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

Canopy Transpiration and Stomatal Responses to Prolonged Drought by a Dominant Desert Species in Central Asia

Directory of Open Access Journals (Sweden)

Daxing Gu

2017-06-01

Full Text Available In arid and semiarid lands, canopy transpiration and its dynamics depend largely on stomatal sensitivity to drought. In this study, the sap flow of a dominant species, Haloxylon ammodendron growing in Central Asian deserts, was monitored using Granier-type sensors, from which the canopy stomatal conductance was derived. The responses of canopy transpiration and stomatal conductance to environmental variables during the second half of the growing season, when annual prolonged drought occurred, was analyzed for four continuous years, from 2013 to 2016. A soil water content (SWC of 3% was identified as the lower soil water threshold for this species, below which the plant lost the ability for stomatal regulation on water loss and suffered the risk of mortality. Above this threshold, the sensitivity of canopy transpiration to vapor pressure deficit, VPD (K, was linearly correlated with SWC, which mainly resulted from different stomatal behaviors at varying drought intensities. Stomatal sensitivity to VPD (m/Gsref increased linearly with soil moisture deficit, inducing a shift from more anisohydric to a more isohydric stomatal behavior. The flexibility of stomatal behavior regarding soil drought was one key element facilitating the survival of H. ammodendron in such an extreme dry environment.

Ion Exchangers NHX1 and NHX2 Mediate Active Potassium Uptake into Vacuoles to Regulate Cell Turgor and Stomatal Function in Arabidopsis[W][OA

Science.gov (United States)

Barragán, Verónica; Leidi, Eduardo O.; Andrés, Zaida; Rubio, Lourdes; De Luca, Anna; Fernández, José A.; Cubero, Beatriz; Pardo, José M.

2012-01-01

Intracellular NHX proteins are Na+,K+/H+ antiporters involved in K+ homeostasis, endosomal pH regulation, and salt tolerance. Proteins NHX1 and NHX2 are the two major tonoplast-localized NHX isoforms. Here, we show that NHX1 and NHX2 have similar expression patterns and identical biochemical activity, and together they account for a significant amount of the Na+,K+/H+ antiport activity in tonoplast vesicles. Reverse genetics showed functional redundancy of NHX1 and NHX2 genes. Growth of the double mutant nhx1 nhx2 was severely impaired, and plants were extremely sensitive to external K+. By contrast, nhx1 nhx2 mutants showed similar sensitivity to salinity stress and even greater rates of Na+ sequestration than the wild type. Double mutants had reduced ability to create the vacuolar K+ pool, which in turn provoked greater K+ retention in the cytosol, impaired osmoregulation, and compromised turgor generation for cell expansion. Genes NHX1 and NHX2 were highly expressed in guard cells, and stomatal function was defective in mutant plants, further compromising their ability to regulate water relations. Together, these results show that tonoplast-localized NHX proteins are essential for active K+ uptake at the tonoplast, for turgor regulation, and for stomatal function. PMID:22438021

Apertures

CERN Document Server

Hansen, R C

2014-01-01

Microwave Scanning Antennas, Volume I: Apertures is a comprehensive account of phased arrays, multiple beam arrays, time domain and synthetic apertures, and adaptive antennas. Advances in continuous apertures and near field theory are discussed. Low noise and monopulse apertures, optical scanners, and large radomes are also covered, along with radio astronomy instruments and associated theory.Comprised of five chapters, this volume begins with an overview of aperture theory as well as aperture distributions and near field theory. The second and third chapters deal with mechanically steered and

Predicting photosynthesis and transpiration responses to ozone: decoupling modeled photosynthesis and stomatal conductance

Directory of Open Access Journals (Sweden)

D. Lombardozzi

2012-08-01

Full Text Available Plants exchange greenhouse gases carbon dioxide and water with the atmosphere through the processes of photosynthesis and transpiration, making them essential in climate regulation. Carbon dioxide and water exchange are typically coupled through the control of stomatal conductance, and the parameterization in many models often predict conductance based on photosynthesis values. Some environmental conditions, like exposure to high ozone (O₃ concentrations, alter photosynthesis independent of stomatal conductance, so models that couple these processes cannot accurately predict both. The goals of this study were to test direct and indirect photosynthesis and stomatal conductance modifications based on O₃ damage to tulip poplar (Liriodendron tulipifera in a coupled Farquhar/Ball-Berry model. The same modifications were then tested in the Community Land Model (CLM to determine the impacts on gross primary productivity (GPP and transpiration at a constant O₃ concentration of 100 parts per billion (ppb. Modifying the V_cmax parameter and directly modifying stomatal conductance best predicts photosynthesis and stomatal conductance responses to chronic O₃ over a range of environmental conditions. On a global scale, directly modifying conductance reduces the effect of O₃ on both transpiration and GPP compared to indirectly modifying conductance, particularly in the tropics. The results of this study suggest that independently modifying stomatal conductance can improve the ability of models to predict hydrologic cycling, and therefore improve future climate predictions.

Closing plant stomata requires a homolog of an aluminum-activated malate transporter.

Science.gov (United States)

Sasaki, Takayuki; Mori, Izumi C; Furuichi, Takuya; Munemasa, Shintaro; Toyooka, Kiminori; Matsuoka, Ken; Murata, Yoshiyuki; Yamamoto, Yoko

2010-03-01

Plant stomata limit both carbon dioxide uptake and water loss; hence, stomatal aperture is carefully set as the environment fluctuates. Aperture area is known to be regulated in part by ion transport, but few of the transporters have been characterized. Here we report that AtALMT12 (At4g17970), a homolog of the aluminum-activated malate transporter (ALMT) of wheat, is expressed in guard cells of Arabidopsis thaliana. Loss-of-function mutations in AtALMT12 impair stomatal closure induced by ABA, calcium and darkness, but do not abolish either the rapidly activated or the slowly activated anion currents previously identified as being important for stomatal closure. Expressed in Xenopus oocytes, AtALMT12 facilitates chloride and nitrate currents, but not those of organic solutes. Therefore, we conclude that AtALMT12 is a novel class of anion transporter involved in stomatal closure.

Sensitivity of stomatal conductance to soil moisture: implications for tropospheric ozone

Directory of Open Access Journals (Sweden)

A. Anav

2018-04-01

Full Text Available Soil moisture and water stress play a pivotal role in regulating stomatal behaviour of plants; however, in the last decade, the role of water availability has often been neglected in atmospheric chemistry modelling studies as well as in integrated risk assessments, despite the fact that plants remove a large amount of atmospheric compounds from the lower troposphere through stomata. The main aim of this study is to evaluate, within the chemistry transport model CHIMERE, the effect of soil water limitation on stomatal conductance and assess the resulting changes in atmospheric chemistry testing various hypotheses of water uptake by plants in the rooting zone. Results highlight how dry deposition significantly declines when soil moisture is used to regulate the stomatal opening, mainly in the semi-arid environments: in particular, over Europe the amount of ozone removed by dry deposition in one year without considering any soil water limitation to stomatal conductance is about 8.5 TgO3, while using a dynamic layer that ensures that plants maximize the water uptake from soil, we found a reduction of about 10 % in the amount of ozone removed by dry deposition ( ∼  7.7 TgO3. Although dry deposition occurs from the top of canopy to ground level, it affects the concentration of gases remaining in the lower atmosphere, with a significant impact on ozone concentration (up to 4 ppb extending from the surface to the upper troposphere (up to 650 hPa. Our results shed light on the importance of improving the parameterizations of processes occurring at plant level (i.e. from the soil to the canopy as they have significant implications for concentration of gases in the lower troposphere and resulting risk assessments for vegetation or human health.

Sensitivity of stomatal conductance to soil moisture: implications for tropospheric ozone

Science.gov (United States)

Anav, Alessandro; Proietti, Chiara; Menut, Laurent; Carnicelli, Stefano; De Marco, Alessandra; Paoletti, Elena

2018-04-01

Soil moisture and water stress play a pivotal role in regulating stomatal behaviour of plants; however, in the last decade, the role of water availability has often been neglected in atmospheric chemistry modelling studies as well as in integrated risk assessments, despite the fact that plants remove a large amount of atmospheric compounds from the lower troposphere through stomata. The main aim of this study is to evaluate, within the chemistry transport model CHIMERE, the effect of soil water limitation on stomatal conductance and assess the resulting changes in atmospheric chemistry testing various hypotheses of water uptake by plants in the rooting zone. Results highlight how dry deposition significantly declines when soil moisture is used to regulate the stomatal opening, mainly in the semi-arid environments: in particular, over Europe the amount of ozone removed by dry deposition in one year without considering any soil water limitation to stomatal conductance is about 8.5 TgO3, while using a dynamic layer that ensures that plants maximize the water uptake from soil, we found a reduction of about 10 % in the amount of ozone removed by dry deposition ( ˜ 7.7 TgO3). Although dry deposition occurs from the top of canopy to ground level, it affects the concentration of gases remaining in the lower atmosphere, with a significant impact on ozone concentration (up to 4 ppb) extending from the surface to the upper troposphere (up to 650 hPa). Our results shed light on the importance of improving the parameterizations of processes occurring at plant level (i.e. from the soil to the canopy) as they have significant implications for concentration of gases in the lower troposphere and resulting risk assessments for vegetation or human health.

Open or close the gate – stomata action under the control of phytohormones in drought stress conditions

Directory of Open Access Journals (Sweden)

Agata eDaszkowska-Golec

2013-05-01

Full Text Available Two highly specialized cells, the guard cells that surround the stomatal pore, are able to integrate environmental and endogenous signals in order to control the stomatal aperture and thereby the gas exchange. The uptake of CO2 is associated with a loss of water by leaves. Control of the size of the stomatal aperture optimizes the efficiency of water use through dynamic changes in the turgor of the guard cells. The opening and closing of stomata is regulated by the integration of environmental signals and endogenous hormonal stimuli. The various different factors to which the guard cells respond translates into the complexity of the network of signaling pathways that control stomatal movements. The perception of an abiotic stress triggers the activation of signal transduction cascades that interact with or are activated by phytohormones. Among these, abscisic acid (ABA, is the best-known stress hormone that closes the stomata, although other phytohormones, such as jasmonic acid, brassinosteroids, cytokinins or ethylene are also involved in the stomatal response to stresses. As a part of the drought response, ABA may interact with jasmonic acid and nitric oxide in order to stimulate stomatal closure. In addition, the regulation of gene expression in response to ABA involves genes that are related to ethylene, cytokinins and auxin signaling. In this paper, recent findings on phytohormone crosstalk, changes in signaling pathways including the expression of specific genes and their impact on modulating stress response through the closing or opening of stomata, together with the highlights of gaps that need to be elucidated in the signaling network of stomatal regulation, are reviewed.

Stomatal characteristics of Eucalyptus grandis clonal hybrids in ...

African Journals Online (AJOL)

This study describes the stomatal response occurring during water stress and subsequent recovery of three Eucalyptus grandis clonal hybrids. The aim was to investigate the degree to which stomatal conductance (gs) and stomatal density differ between the clonal hybrids across seasons and in response to water stress.

Opinion: the red-light response of stomatal movement is sensed by the redox state of the photosynthetic electron transport chain.

Science.gov (United States)

Busch, Florian A

2014-02-01

Guard cells regulate CO2 uptake and water loss of a leaf by controlling stomatal movement in response to environmental factors such as CO2, humidity, and light. The mechanisms by which stomata respond to red light are actively debated in the literature, and even after decades of research it is still controversial whether stomatal movement is related to photosynthesis or not. This review summarizes the current knowledge of the red-light response of stomata. A comparison of published evidence suggests that stomatal movement is controlled by the redox state of photosynthetic electron transport chain components, in particular the redox state of plastoquinone. Potential consequences for the modeling of stomatal conductance are discussed.

Adaxial/abaxial specification in the regulation of photosynthesis and stomatal opening with respect to light orentation and growth with CO2 enrichment in the C4 species Paspalum dilatatum

NARCIS (Netherlands)

Soares, A.S.; Discoll, S.P.; Olmos, E.; Harbinson, J.; Arrabaca, M.C.

2008-01-01

Whole-plant morphology, leaf structure and composition were studied together with the effects of light orientation on the dorso-ventral regulation of photosynthesis and stomatal conductance in Paspalum dilatatum cv. Raki plants grown for 6 wk at either 350 or 700 µl l¿1 CO2. Plant biomass was

Modeling stomatal conductance in the earth system: linking leaf water-use efficiency and water transport along the soil-plant-atmosphere continuum

Science.gov (United States)

Bonan, G. B.; Williams, M.; Fisher, R. A.; Oleson, K. W.

2014-09-01

The Ball-Berry stomatal conductance model is commonly used in earth system models to simulate biotic regulation of evapotranspiration. However, the dependence of stomatal conductance (gs) on vapor pressure deficit (Ds) and soil moisture must be empirically parameterized. We evaluated the Ball-Berry model used in the Community Land Model version 4.5 (CLM4.5) and an alternative stomatal conductance model that links leaf gas exchange, plant hydraulic constraints, and the soil-plant-atmosphere continuum (SPA). The SPA model simulates stomatal conductance numerically by (1) optimizing photosynthetic carbon gain per unit water loss while (2) constraining stomatal opening to prevent leaf water potential from dropping below a critical minimum. We evaluated two optimization algorithms: intrinsic water-use efficiency (ΔAn /Δgs, the marginal carbon gain of stomatal opening) and water-use efficiency (ΔAn /ΔEl, the marginal carbon gain of transpiration water loss). We implemented the stomatal models in a multi-layer plant canopy model to resolve profiles of gas exchange, leaf water potential, and plant hydraulics within the canopy, and evaluated the simulations using leaf analyses, eddy covariance fluxes at six forest sites, and parameter sensitivity analyses. The primary differences among stomatal models relate to soil moisture stress and vapor pressure deficit responses. Without soil moisture stress, the performance of the SPA stomatal model was comparable to or slightly better than the CLM Ball-Berry model in flux tower simulations, but was significantly better than the CLM Ball-Berry model when there was soil moisture stress. Functional dependence of gs on soil moisture emerged from water flow along the soil-to-leaf pathway rather than being imposed a priori, as in the CLM Ball-Berry model. Similar functional dependence of gs on Ds emerged from the ΔAn/ΔEl optimization, but not the ΔAn /gs optimization. Two parameters (stomatal efficiency and root hydraulic

Optimal stomatal behaviour around the world

DEFF Research Database (Denmark)

Lin, Yan-Shih; Medlyn, Belinda E.; Duursma, Remko A.

2015-01-01

, a globalscale database and an associated globally applicable model of gs that allow predictions of stomatal behaviour are lacking. Here,we present a database of globally distributed gs obtained in the field for a wide range of plant functional types (PFTs) and biomes. We find that stomatal behaviour diers among...

Thermal infrared imaging of the temporal variability in stomatal conductance for fruit trees

Science.gov (United States)

Struthers, Raymond; Ivanova, Anna; Tits, Laurent; Swennen, Rony; Coppin, Pol

2015-07-01

Repeated measurements using thermal infrared remote sensing were used to characterize the change in canopy temperature over time and factors that influenced this change on 'Conference' pear trees (Pyrus communis L.). Three different types of sensors were used, a leaf porometer to measure leaf stomatal conductance, a thermal infrared camera to measure the canopy temperature and a meteorological sensor to measure weather variables. Stomatal conductance of water stressed pear was significantly lower than in the control group 9 days after stress began. This decrease in stomatal conductance reduced transpiration, reducing evaporative cooling that increased canopy temperature. Using thermal infrared imaging with wavelengths between 7.5 and13 μm, the first significant difference was measured 18 days after stress began. A second order derivative described the average rate of change of the difference between the stress treatment and control group. The average rate of change for stomatal conductance was 0.06 (mmol m-2 s-1) and for canopy temperature was -0.04 (°C) with respect to days. Thermal infrared remote sensing and data analysis presented in this study demonstrated that the differences in canopy temperatures between the water stress and control treatment due to stomata regulation can be validated.

Optimal stomatal behaviour around the world

Science.gov (United States)

Lin, Yan-Shih; Medlyn, Belinda E.; Duursma, Remko A.; Prentice, I. Colin; Wang, Han; Baig, Sofia; Eamus, Derek; de Dios, Victor Resco; Mitchell, Patrick; Ellsworth, David S.; de Beeck, Maarten Op; Wallin, Göran; Uddling, Johan; Tarvainen, Lasse; Linderson, Maj-Lena; Cernusak, Lucas A.; Nippert, Jesse B.; Ocheltree, Troy W.; Tissue, David T.; Martin-Stpaul, Nicolas K.; Rogers, Alistair; Warren, Jeff M.; de Angelis, Paolo; Hikosaka, Kouki; Han, Qingmin; Onoda, Yusuke; Gimeno, Teresa E.; Barton, Craig V. M.; Bennie, Jonathan; Bonal, Damien; Bosc, Alexandre; Löw, Markus; Macinins-Ng, Cate; Rey, Ana; Rowland, Lucy; Setterfield, Samantha A.; Tausz-Posch, Sabine; Zaragoza-Castells, Joana; Broadmeadow, Mark S. J.; Drake, John E.; Freeman, Michael; Ghannoum, Oula; Hutley, Lindsay B.; Kelly, Jeff W.; Kikuzawa, Kihachiro; Kolari, Pasi; Koyama, Kohei; Limousin, Jean-Marc; Meir, Patrick; Lola da Costa, Antonio C.; Mikkelsen, Teis N.; Salinas, Norma; Sun, Wei; Wingate, Lisa

2015-05-01

Stomatal conductance (gs) is a key land-surface attribute as it links transpiration, the dominant component of global land evapotranspiration, and photosynthesis, the driving force of the global carbon cycle. Despite the pivotal role of gs in predictions of global water and carbon cycle changes, a global-scale database and an associated globally applicable model of gs that allow predictions of stomatal behaviour are lacking. Here, we present a database of globally distributed gs obtained in the field for a wide range of plant functional types (PFTs) and biomes. We find that stomatal behaviour differs among PFTs according to their marginal carbon cost of water use, as predicted by the theory underpinning the optimal stomatal model and the leaf and wood economics spectrum. We also demonstrate a global relationship with climate. These findings provide a robust theoretical framework for understanding and predicting the behaviour of gs across biomes and across PFTs that can be applied to regional, continental and global-scale modelling of ecosystem productivity, energy balance and ecohydrological processes in a future changing climate.

Tumor Necrosis Factor-Mediated Survival of CD169+ Cells Promotes Immune Activation during Vesicular Stomatitis Virus Infection

DEFF Research Database (Denmark)

Shinde, Prashant V; Xu, Haifeng C; Maney, Sathish Kumar

2018-01-01

Innate immune activation is essential to mount an effective antiviral response and to prime adaptive immunity. Although a crucial role of CD169(+) cells during vesicular stomatitis virus (VSV) infections is increasingly recognized, factors regulating CD169(+) cells during viral infections remain...... stomatitis virus infection, phagocytes produce tumor necrosis factor (TNF) which signals via TNFR1 and promote "enforced virus replication" in CD169(+) macrophages. Consequently, lack of TNF or TNFR1 resulted in defective immune activation and VSV clearance....

Transmission and pathogenesis of vesicular stomatitis viruses

Science.gov (United States)

Vesicular Stomatitis (VS) is caused by the Vesicular Stomatitis Virus (VSV), a negative single stranded RNA arthropod-borne virus member of the Family Rhabdoviridae. The virion is composed of the host derived plasma membrane, the envelope, and an internal ribonucleoprotein core. The envelope contain...

Stomatal uptake and stomatal deposition of ozone in isoprene and monoterpene emitting plants.

Science.gov (United States)

Fares, S; Loreto, F; Kleist, E; Wildt, J

2008-01-01

Volatile isoprenoids were reported to protect plants against ozone. To understand whether this could be the result of a direct scavenging of ozone by these molecules, the stomatal and non-stomatal uptake of ozone was estimated in plants emitting isoprene or monoterpenes. Ozone uptake by holm oak (Quercus ilex, a monoterpene emitter) and black poplar (Populus nigra, an isoprene emitter) was studied in whole plant enclosures (continuously stirred tank reactors, CSTR). The ozone uptake by plants was estimated measuring ozone concentration at the inlet and outlet of the reactors, after correcting for the uptake of the enclosure materials. Destruction of ozone at the cuticle or at the plant stems was found to be negligible compared to the ozone uptake through the stomata. For both plant species, a relationship between stomatal conductance and ozone uptake was found. For the poplar, the measured ozone losses were explained by the uptake of ozone through the stomata only, and ozone destruction by gas phase reactions with isoprene was negligible. For the oak, gas phase reactions of ozone with the monoterpenes emitted by the plants contributed significantly to ozone destruction. This was confirmed by two different experiments showing a) that in cases of high stomatal conductance but under low CO(2) concentration, a reduction of monoterpene emission was still associated with reduced O(3) uptake; and b) that ozone losses due to the gas phase reactions only can be measured when using the exhaust from a plant chamber to determine the gas phase reactivity in an empty reaction chamber. Monoterpenes can therefore relevantly scavenge ozone at leaf level contributing to protection against ozone.

Ecology of Candida-associated Denture Stomatitis

OpenAIRE

Budtz-Jørgensen, Ejvind

2011-01-01

Introduction of a prosthesis into the oral cavity results in profound alterations of the environmental conditions as the prosthesis and the underlying mucosa become colonized with oral microorganisms, including Candida spp. This may lead to denture stomatitis, a non-specific inflammatory reaction against microbial antigens, toxins and enzymes produced by the colonizing microorganisms. The role of Candida in the etiology of denture stomatitis is indicated by an increased number of yeasts on th...

Optimal Stomatal Behaviour Around the World: Synthesis of a Global Stomatal Conductance Database and Scaling from Leaf to Ecosystem

Science.gov (United States)

Lin, Y. S.; Medlyn, B. E.; Duursma, R.; Prentice, I. C.; Wang, H.

2014-12-01

Stomatal conductance (gs) is a key land surface attribute as it links transpiration, the dominant component of global land evapotranspiration and a key element of the global water cycle, and photosynthesis, the driving force of the global carbon cycle. Despite the pivotal role of gs in predictions of global water and carbon cycles, a global scale database and an associated globally applicable model of gs that allow predictions of stomatal behaviour are lacking. We present a unique database of globally distributed gs obtained in the field for a wide range of plant functional types (PFTs) and biomes. We employed a model of optimal stomatal conductance to assess differences in stomatal behaviour, and estimated the model slope coefficient, g1, which is directly related to the marginal carbon cost of water, for each dataset. We found that g1 varies considerably among PFTs, with evergreen savanna trees having the largest g1 (least conservative water use), followed by C3 grasses and crops, angiosperm trees, gymnosperm trees, and C4 grasses. Amongst angiosperm trees, species with higher wood density had a higher marginal carbon cost of water, as predicted by the theory underpinning the optimal stomatal model. There was an interactive effect between temperature and moisture availability on g1: for wet environments, g1 was largest in high temperature environments, indicated by high mean annual temperature during the period when temperature above 0oC (Tm), but it did not vary with Tm across dry environments. We examine whether these differences in leaf-scale behaviour are reflected in ecosystem-scale differences in water-use efficiency. These findings provide a robust theoretical framework for understanding and predicting the behaviour of stomatal conductance across biomes and across PFTs that can be applied to regional, continental and global-scale modelling of productivity and ecohydrological processes in a future changing climate.

Solar-induced chlorophyll fluorescence tracks the trend of canopy stomatal conductance and transpiration at diurnal and seasonal scales

Science.gov (United States)

Zhang, Y.; Shan, N.; Ju, W.; Chen, J.

2017-12-01

Transpiration is the process of plant water loss through the stomata on the leaf surface and plays a key role in the energy and water balance of the land surface. Plant stomata function as a control interface for regulating photosynthetic uptake of CO2 and transpiration, strongly linked to plant productivity. Stomatal conductance is fundamental to larger-scale regional prediction of carbon-water cycles and their feedbacks to climate. The widely used Ball-Berry model coupled photosynthesis to a semi-empirical model of stomatal conductance. However large uncertainties remain in simulation of carbon assimilation rate in ecosystem and regional scales. The strong correlations of solar-induced fluorescence (SIF) and GPP have been demonstrated and provides an important opportunity to accurately monitor photosynthetic activity and water exchange. In this presentation, we compared both canopy-observed SIF and satellite-derived SIF with tower-based canopy stomatal conductance from hourly to 8-day scales in forest and cropland ecosystem. Using the model of stomatal conductance based on SIF, the transpiration was estimated at hourly and daily scales and compared with flux tower measurements. The results showed that the seasonal pattern of canopy stomatal conductance agreed better with SIF compared to NDVI and their relationship was higher during sunny days for forest ecosystem. Canopy stomatal conductance correlated with both tower-observed SIF and SIF from the Global Ozone Monitoring Experiment-2. Estimation of transpiration from SIF performed well in both forest and cropland ecosystem. This remotely sensed approaches from SIF for modelling stomatal conductance opens a new era to analysis and simulation of coupled carbon and water cycles under climate change.

Application of thermography for monitoring stomatal conductance of Coffea arabica under different shading systems.

Science.gov (United States)

Craparo, A C W; Steppe, K; Van Asten, P J A; Läderach, P; Jassogne, L T P; Grab, S W

2017-12-31

Stomatal regulation is a key process in the physiology of Coffea arabica (C. arabica). Intrinsically linked to photosynthesis and water relations, it provides insights into the plant's adaptive capacity, survival and growth. The ability to rapidly quantify this parameter for C. arabica under different agroecological systems would be an indispensable tool. Using a Flir E6 MIR Camera, an index that is equivalent to stomatal conductance (I g ) was compared with stomatal conductance measurements (g s ) in a mature coffee plantation. In order to account for varying meteorological conditions between days, the methods were also compared under stable meteorological conditions in a laboratory and I g was also converted to absolute stomatal conductance values (g 1 ). In contrast to typical plant-thermography methods which measure indices once per day over an extended time period, we used high resolution hourly measurements over daily time series with 9 sun and 9 shade replicates. Eight daily time series showed a strong correlation between methods, while the remaining 10 were not significant. Including several other meteorological parameters in the calculation of g 1 did not contribute to any stronger correlation between methods. Total pooled data (combined daily series) resulted in a correlation of ρ=0.66 (P≤2.2e-16), indicating that our approach is particularly useful for situations where absolute values of stomatal conductance are not required, such as for comparative purposes, screening or trend analysis. We use the findings to advance the protocol for a more accurate methodology which may assist in quantifying advantageous microenvironment designs for coffee, considering the current and future climates of coffee growing regions. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Co-ordination of physiological and morphological responses of stomata to elevated [CO2] in vascular plants.

Science.gov (United States)

Haworth, Matthew; Elliott-Kingston, Caroline; McElwain, Jennifer C

2013-01-01

Plant stomata display a wide range of short-term behavioural and long-term morphological responses to atmospheric carbon dioxide concentration ([CO(2)]). The diversity of responses suggests that plants may have different strategies for controlling gas exchange, yet it is not known whether these strategies are co-ordinated in some way. Here, we test the hypothesis that there is co-ordination of physiological (via aperture change) and morphological (via stomatal density change) control of gas exchange by plants. We examined the response of stomatal conductance (G(s)) to instantaneous changes in external [CO(2)] (C(a)) in an evolutionary cross-section of vascular plants grown in atmospheres of elevated [CO(2)] (1,500 ppm) and sub-ambient [O(2)] (13.0 %) compared to control conditions (380 ppm CO(2), 20.9 % O(2)). We found that active control of stomatal aperture to [CO(2)] above current ambient levels was not restricted to angiosperms, occurring in the gymnosperms Lepidozamia peroffskyana and Nageia nagi. The angiosperm species analysed appeared to possess a greater respiratory demand for stomatal movement than gymnosperm species displaying active stomatal control. Those species with little or no control of stomatal aperture (termed passive) to C(a) were more likely to exhibit a reduction in stomatal density than species with active stomatal control when grown in atmospheres of elevated [CO(2)]. The relationship between the degree of stomatal aperture control to C(a) above ambient and the extent of any reduction in stomatal density may suggest the co-ordination of physiological and morphological responses of stomata to [CO(2)] in the optimisation of water use efficiency. This trade-off between stomatal control strategies may have developed due to selective pressures exerted by the costs associated with passive and active stomatal control.

Chronic gingivitis and aphthous stomatitis relationship hypothesis: A neuroimmunobiological approach

Directory of Open Access Journals (Sweden)

Chiquita Prahasanti

2009-03-01

Full Text Available Background: Traumatic injuries to the oral mucosa in fixed orthodontic patients are common, especially in the first week of bracket placement, and occasionally lead to the development of aphthous stomatitis or ulcers. Nevertheless, these lesions are selflimiting. Purpose: The objective of this study is to reveal the connection between chronic gingivitis and aphthous stomatitis which is still unclear. Case: A patient with a persistent lesion for more than six months. Case Management: RAS was treated with scaling procedure, the gingival inflammation was healed. However, in this case report, despite the appropriate management procedures had been done, the lesion still worsen and became more painful. Moreover, the symptoms did not heal for more than two weeks. Actually, they had been undergone orthodontic treatment more than six months and rarely suffered from aphthous stomatitis. Coincidentally, at that time they also suffered from chronic gingivitis. It was interesting that after scaling procedures, the ulcer subsides in two days. Conclusion: Recently, the neuroimmunobiological researches which involved neurotransmitters and cytokines on cell-nerve signaling, and heat shock proteins in gingivitis and stomatitis are in progress. Nevertheless, they were done separately, thus do not explain the interrelationship. This proposed new concept which based on an integrated neuroimmunobiological approach could explain the benefit of periodontal treatment, especially scaling procedures, for avoiding prolonged painful episodes and unnecessary medications in aphthous stomatitis. However, for widely acceptance of the chronic gingivitis and aphthous stomatitis relationship, further clinical and laboratory study should be done. Regarding to the relatively fast healing after scaling procedures in this case report; it was concluded that the connection between chronic gingivitis and aphthous stomatitis is possible.

14-3-3 Proteins in Guard Cell Signaling.

Science.gov (United States)

Cotelle, Valérie; Leonhardt, Nathalie

2015-01-01

Guard cells are specialized cells located at the leaf surface delimiting pores which control gas exchanges between the plant and the atmosphere. To optimize the CO2 uptake necessary for photosynthesis while minimizing water loss, guard cells integrate environmental signals to adjust stomatal aperture. The size of the stomatal pore is regulated by movements of the guard cells driven by variations in their volume and turgor. As guard cells perceive and transduce a wide array of environmental cues, they provide an ideal system to elucidate early events of plant signaling. Reversible protein phosphorylation events are known to play a crucial role in the regulation of stomatal movements. However, in some cases, phosphorylation alone is not sufficient to achieve complete protein regulation, but is necessary to mediate the binding of interactors that modulate protein function. Among the phosphopeptide-binding proteins, the 14-3-3 proteins are the best characterized in plants. The 14-3-3s are found as multiple isoforms in eukaryotes and have been shown to be involved in the regulation of stomatal movements. In this review, we describe the current knowledge about 14-3-3 roles in the regulation of their binding partners in guard cells: receptors, ion pumps, channels, protein kinases, and some of their substrates. Regulation of these targets by 14-3-3 proteins is discussed and related to their function in guard cells during stomatal movements in response to abiotic or biotic stresses.

ROS signaling and stomatal movement in plant responses to drought stress and pathogen attack.

Science.gov (United States)

Qi, Junsheng; Song, Chun-Peng; Wang, Baoshan; Zhou, Jianmin; Kangasjärvi, Jaakko; Zhu, Jian-Kang; Gong, Zhizhong

2018-04-16

Stomata, the pores formed by a pair of guard cells, are the main gateways for water transpiration and photosynthetic CO 2 exchange, as well as pathogen invasion in land plants. Guard cell movement is regulated by a combination of environmental factors including water status, light, CO 2 levels and pathogen attack, as well as endogenous signals such as abscisic acid and apoplastic reactive oxygen species (ROS). Under abiotic and biotic stress conditions, extracellular ROS are mainly produced by plasma membrane-localized NADPH oxidases, whereas intracellular ROS are produced in multiple organelles. These ROS form a sophisticated cellular signaling network, with the accumulation of apoplastic ROS an early hallmark of stomatal movement. Here, we review recent progress in understanding the molecular mechanisms of the ROS signaling network, primarily during drought stress and pathogen attack. We summarize the roles of apoplastic ROS in regulating stomatal movement, ABA and CO 2 signaling, and immunity responses. Finally, we discuss ROS accumulation and communication between organelles and cells. This information provides a conceptual framework for understanding how ROS signaling is integrated with various signaling pathways during plant responses to abiotic and biotic stress stimuli. This article is protected by copyright. All rights reserved.

Phase dependence of transport-aperture coordination variability reveals control strategy of reach-to-grasp movements.

Science.gov (United States)

Rand, Miya K; Shimansky, Y P; Hossain, Abul B M I; Stelmach, George E

2010-11-01

Based on an assumption of movement control optimality in reach-to-grasp movements, we have recently developed a mathematical model of transport-aperture coordination (TAC), according to which the hand-target distance is a function of hand velocity and acceleration, aperture magnitude, and aperture velocity and acceleration (Rand et al. in Exp Brain Res 188:263-274, 2008). Reach-to-grasp movements were performed by young adults under four different reaching speeds and two different transport distances. The residual error magnitude of fitting the above model to data across different trials and subjects was minimal for the aperture-closure phase, but relatively much greater for the aperture-opening phase, indicating considerable difference in TAC variability between those phases. This study's goal is to identify the main reasons for that difference and obtain insights into the control strategy of reach-to-grasp movements. TAC variability within the aperture-opening phase of a single trial was found minimal, indicating that TAC variability between trials was not due to execution noise, but rather a result of inter-trial and inter-subject variability of motor plan. At the same time, the dependence of the extent of trial-to-trial variability of TAC in that phase on the speed of hand transport was sharply inconsistent with the concept of speed-accuracy trade-off: the lower the speed, the larger the variability. Conversely, the dependence of the extent of TAC variability in the aperture-closure phase on hand transport speed was consistent with that concept. Taking into account recent evidence that the cost of neural information processing is substantial for movement planning, the dependence of TAC variability in the aperture-opening phase on task performance conditions suggests that it is not the movement time that the CNS saves in that phase, but the cost of neuro-computational resources and metabolic energy required for TAC regulation in that phase. Thus, the CNS

Reconstructing Atmospheric CO2 Through The Paleocene-Eocene Thermal Maximum Using Stomatal Index and Stomatal Density Values From Ginkgo adiantoides

Science.gov (United States)

Barclay, R. S.; Wing, S. L.

2013-12-01

The Paleocene-Eocene Thermal Maximum (PETM) was a geologically brief interval of intense global warming 56 million years ago. It is arguably the best geological analog for a worst-case scenario of anthropogenic carbon emissions. The PETM is marked by a ~4-6‰ negative carbon isotope excursion (CIE) and extensive marine carbonate dissolution, which together are powerful evidence for a massive addition of carbon to the oceans and atmosphere. In spite of broad agreement that the PETM reflects a large carbon cycle perturbation, atmospheric concentrations of CO2 (pCO2) during the event are not well constrained. The goal of this study is to produce a high resolution reconstruction of pCO2 using stomatal frequency proxies (both stomatal index and stomatal density) before, during, and after the PETM. These proxies rely upon a genetically controlled mechanism whereby plants decrease the proportion of gas-exchange pores (stomata) in response to increased pCO2. Terrestrial sections in the Bighorn Basin, Wyoming, contain macrofossil plants with cuticle immediately bracketing the PETM, as well as dispersed plant cuticle from within the body of the CIE. These fossils allow for the first stomatal-based reconstruction of pCO2 near the Paleocene-Eocene boundary; we also use them to determine the relative timing of pCO2 change in relation to the CIE that defines the PETM. Preliminary results come from macrofossil specimens of Ginkgo adiantoides, collected from an ~200ka interval prior to the onset of the CIE (~230-30ka before), and just after the 'recovery interval' of the CIE. Stomatal index values decreased by 37% within an ~70ka time interval at least 100ka prior to the onset of the CIE. The decrease in stomatal index is interpreted as a significant increase in pCO2, and has a magnitude equivalent to the entire range of stomatal index adjustment observed in modern Ginkgo biloba during the anthropogenic CO2 rise during the last 150 years. The inferred CO2 increase prior to the

Improving stomatal functioning at elevated growth air humidity: A review.

Science.gov (United States)

Fanourakis, Dimitrios; Bouranis, Dimitrios; Giday, Habtamu; Carvalho, Dália R A; Rezaei Nejad, Abdolhossein; Ottosen, Carl-Otto

2016-12-01

Plants grown at high relative air humidity (RH≥85%) are prone to lethal wilting upon transfer to conditions of high evaporative demand. The reduced survival of these plants is related to (i) increased cuticular permeability, (ii) changed anatomical features (i.e., longer pore length and higher stomatal density), (iii) reduced rehydration ability, (iv) impaired water potential sensitivity to leaf dehydration and, most importantly, (v) compromised stomatal closing ability. This review presents a critical analysis of the strategies which stimulate stomatal functioning during plant development at high RH. These include (a) breeding for tolerant cultivars, (b) interventions with respect to the belowground environment (i.e., water deficit, increased salinity, nutrient culture and grafting) as well as (c) manipulation of the aerial environment [i.e., increased proportion of blue light, increased air movement, temporal temperature rise, and spraying with abscisic acid (ABA)]. Root hypoxia, mechanical disturbance, as well as spraying with compounds mimicking ABA, lessening its inactivation or stimulating its within-leaf redistribution are also expected to improve stomatal functioning of leaves expanded in humid air. Available evidence leaves little doubt that genotypic and phenotypic differences in stomatal functioning following cultivation at high RH are realized through the intermediacy of ABA. Copyright © 2016 Elsevier GmbH. All rights reserved.

Natural variation in stomatal response to closing stimuli among Arabidopsis thaliana accessions after exposure to low VPD as a tool to recognize the mechanism of disturbed stomatal functioning.

Science.gov (United States)

Aliniaeifard, Sasan; van Meeteren, Uulke

2014-12-01

Stomatal responses to closing stimuli are disturbed after long-term exposure of plants to low vapour pressure deficit (VPD). The mechanism behind this disturbance is not fully understood. Genetic variation between naturally occurring ecotypes can be helpful to elucidate the mechanism controlling stomatal movements in different environments. We characterized the stomatal responses of 41 natural accessions of Arabidopsis thaliana to closing stimuli (ABA and desiccation) after they had been exposed for 4 days to moderate VPD (1.17 kPa) or low VPD (0.23 kPa). A fast screening system was used to test stomatal response to ABA using chlorophyll fluorescence imaging under low O2 concentrations of leaf discs floating on ABA solutions. In all accessions stomatal conductance (gs) was increased after prior exposure to low VPD. After exposure to low VPD, stomata of 39 out of 41 of the accessions showed a diminished ABA closing response; only stomata of low VPD-exposed Map-42 and C24 were as responsive to ABA as moderate VPD-exposed plants. In response to desiccation, most of the accessions showed a normal stomata closing response following low VPD exposure. Only low VPD-exposed Cvi-0 and Rrs-7 showed significantly less stomatal closure compared with moderate VPD-exposed plants. Using principle component analysis (PCA), accessions could be categorized to very sensitive, moderately sensitive, and less sensitive to closing stimuli. In conclusion, we present evidence for different stomatal responses to closing stimuli after long-term exposure to low VPD across Arabidopsis accessions. The variation can be a useful tool for finding the mechanism of stomatal malfunctioning. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Comparisons of coded aperture imaging using various apertures and decoding methods

International Nuclear Information System (INIS)

Chang, L.T.; Macdonald, B.; Perez-Mendez, V.

1976-07-01

The utility of coded aperture γ camera imaging of radioisotope distributions in Nuclear Medicine is in its ability to give depth information about a three dimensional source. We have calculated imaging with Fresnel zone plate and multiple pinhole apertures to produce coded shadows and reconstruction of these shadows using correlation, Fresnel diffraction, and Fourier transform deconvolution. Comparisons of the coded apertures and decoding methods are made by evaluating their point response functions both for in-focus and out-of-focus image planes. Background averages and standard deviations were calculated. In some cases, background subtraction was made using combinations of two complementary apertures. Results using deconvolution reconstruction for finite numbers of events are also given

Salicaceae Endophytes Modulate Stomatal Behavior and Increase Water Use Efficiency in Rice

Directory of Open Access Journals (Sweden)

Hyungmin Rho

2018-03-01

Full Text Available Bacterial and yeast endophytes isolated from the Salicaceae family have been shown to promote growth and alleviate stress in plants from different taxa. To determine the physiological pathways through which endophytes affect plant water relations, we investigated leaf water potential, whole-plant water use, and stomatal responses of rice plants to Salicaceae endophyte inoculation under CO2 enrichment and water deficit. Daytime stomatal conductance and stomatal density were lower in inoculated plants compared to controls. Leaf ABA concentrations increased with endophyte inoculation. As a result, transpirational water use decreased significantly with endophyte inoculation while biomass did not change or slightly increased. This response led to a significant increase in cumulative water use efficiency at harvest. Different endophyte strains produced the same results in host plant water relations and stomatal responses. These stomatal responses were also observed under elevated CO2 conditions, and the increase in water use efficiency was more pronounced under water deficit conditions. The effect on water use efficiency was positively correlated with daily light integrals across different experiments. Our results provide insights on the physiological mechanisms of plant-endophyte interactions involving plant water relations and stomatal functions.

[CORRELATION MATRIX OF CHARACTERISTICS OF CHRONIC RECURRENT APHTHOUS STOMATITIS].

Science.gov (United States)

Koridze, Kh; Aladashvili, L; Taboridze, I

2015-09-01

The purpose of the present work is to study the correlation between the risk factors of chronic recurrent aphthous stomatitis. The research was conducted on 62 patients between ages of 40 and 70 years at Tbilisi Hospital for Veterans of War. The analysis was carried out by Spearman's Rank Correlation method using the statistical package SPSS 11.5. We investigated: harmful habits, professional factors, background and accompanying illnesses, pathology of teeth, focal infection, emotional stress, genetic factors. Correlation matrix between the significant risk factors of chronic recurrent aphthous stomatitis is defined. Multiple correlations have the following factors: industrial dust, focal infections, emotional stress, anemia. Correlation diagram of etiological factors of chronic recurrent aphthous stomatitis is helpful for providing professional and expert services.

Improvement of herpetic stomatitis therapy in patients with chronic tonsillitis

Directory of Open Access Journals (Sweden)

Lepilin А.V.

2011-12-01

Full Text Available The research goal is to determine the clinical and pathogenetic efficacy of Cycloferon liniment in the combined therapy in patients with herpetic stomatitis accompanied by chronic tonsillitis. Materials and methods: Medical examination and treatment of 60 patients have been carried out. The marker of endogenous intoxication, infectious severity and immunity has been investigated. Results. It has been established that use of Cycloferon liniment in the combined therapy in patients with herpetic stomatitis accompanied by chronic tonsillitis has allowed to decrease infectious severity in par-odontal recess and evidence of local inflammation, to normalize immunity indices and reduce the level of endogenous intoxication that has been liable for acceleration of recuperation processes and lowering of frequency of stomatitis recurrences. Conclusion. The clinical efficacy of Cycloferon liniment in the therapy in patients with herpetic stomatitis accompanied by chronic tonsillitis conditioned by the decreasing of activity of local inflammatory process according to the reducing of level pro-inflammatory cytokines, infectious burden of the mouth cavity, endogenous intoxication

Regulation of photosynthesis and stomatal and mesophyll conductance under water stress and recovery in olive trees: correlation with gene expression of carbonic anhydrase and aquaporins.

Science.gov (United States)

Perez-Martin, Alfonso; Michelazzo, Chiara; Torres-Ruiz, Jose M; Flexas, Jaume; Fernández, José E; Sebastiani, Luca; Diaz-Espejo, Antonio

2014-07-01

The hypothesis that aquaporins and carbonic anhydrase (CA) are involved in the regulation of stomatal (g s) and mesophyll (g m) conductance to CO2 was tested in a short-term water-stress and recovery experiment in 5-year-old olive plants (Olea europaea) growing outdoors. The evolution of leaf gas exchange, chlorophyll fluorescence, and plant water status, and a quantitative analysis of photosynthesis limitations, were followed during water stress and recovery. These variables were correlated with gene expression of the aquaporins OePIP1.1 and OePIP2.1, and stromal CA. At mild stress and at the beginning of the recovery period, stomatal limitations prevailed, while the decline in g m accounted for up to 60% of photosynthesis limitations under severe water stress. However, g m was restored to control values shortly after rewatering, facilitating the recovery of the photosynthetic rate. CA was downregulated during water stress and upregulated after recovery. The use of structural equation modelling allowed us to conclude that both OePIP1.1 and OePIP2.1 expression could explain most of the variations observed for g s and g m. CA expression also had a small but significant effect on g m in olive under water-stress conditions. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Aperture Photometry Tool

Science.gov (United States)

Laher, Russ R.; Gorjian, Varoujan; Rebull, Luisa M.; Masci, Frank J.; Fowler, John W.; Helou, George; Kulkarni, Shrinivas R.; Law, Nicholas M.

2012-07-01

Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It is a graphical user interface (GUI) designed to allow the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. The finely tuned layout of the GUI, along with judicious use of color-coding and alerting, is intended to give maximal user utility and convenience. Simply mouse-clicking on a source in the displayed image will instantly draw a circular or elliptical aperture and sky annulus around the source and will compute the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs with just the push of a button, including image histogram, x and y aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has many functions for customizing the calculations, including outlier rejection, pixel “picking” and “zapping,” and a selection of source and sky models. The radial-profile-interpolation source

Parameters for HL-LHC aperture calculations and comparison with aperture measurements

CERN Document Server

Bruce, R; Fartoukh, S; Giovannozzi, M; Redaelli, S; Tomas, R; Wenninger, J

2014-01-01

When β∗ is squeezed to smaller values in the LHC, the beam size in the inner triplet increases so that the aperture risks to be exposed to unwanted beam losses. A 2D calculation model was used during the design stage to study the aperture margins, both there and at other potential bottlenecks. Based on assumptions on orbit and optics errors, as well as mechanical tolerances, it gives the available aperture in units of the RMS beam size, which can be compared with what can be protected by the collimation system. During the LHC Run I in 2010-2013, several of the error tolerances have been found smaller than the design assumptions. Furthermore, the aperture has been measured with beam several times and the results are compatible with a very well aligned machine, with results close to the design values. In this report, we therefore review the assumptions in the model and propose an updated set of input parameters to be used for aperture calculations at top energy in HL-LHC. The new parameter set is based on th...

Quantitative model of transport-aperture coordination during reach-to-grasp movements.

Science.gov (United States)

Rand, Miya K; Shimansky, Y P; Hossain, Abul B M I; Stelmach, George E

2008-06-01

It has been found in our previous studies that the initiation of aperture closure during reach-to-grasp movements occurs when the hand distance to target crosses a threshold that is a function of peak aperture amplitude, hand velocity, and hand acceleration. Thus, a stable relationship between those four movement parameters is observed at the moment of aperture closure initiation. Based on the concept of optimal control of movements (Naslin 1969) and its application for reach-to-grasp movement regulation (Hoff and Arbib 1993), it was hypothesized that the mathematical equation expressing that relationship can be generalized to describe coordination between hand transport and finger aperture during the entire reach-to-grasp movement by adding aperture velocity and acceleration to the above four movement parameters. The present study examines whether this hypothesis is supported by the data obtained in experiments in which young adults performed reach-to-grasp movements in eight combinations of two reach-amplitude conditions and four movement-speed conditions. It was found that linear approximation of the mathematical model described the relationship among the six movement parameters for the entire aperture-closure phase with very high precision for each condition, thus supporting the hypothesis for that phase. Testing whether one mathematical model could approximate the data across all the experimental conditions revealed that it was possible to achieve the same high level of data-fitting precision only by including in the model two additional, condition-encoding parameters and using a nonlinear, artificial neural network-based approximator with two hidden layers comprising three and two neurons, respectively. This result indicates that transport-aperture coordination, as a specific relationship between the parameters of hand transport and finger aperture, significantly depends on the condition-encoding variables. The data from the aperture-opening phase also fit a

Detailed IR aperture measurements

CERN Document Server

Bruce, Roderik; Garcia Morales, Hector; Giovannozzi, Massimo; Hermes, Pascal Dominik; Mirarchi, Daniele; Quaranta, Elena; Redaelli, Stefano; Rossi, Carlo; Skowronski, Piotr Krzysztof; Wretborn, Sven Joel; CERN. Geneva. ATS Department

2016-01-01

MD 1673 was carried out on October 5 2016, in order to investigate in more detail the available aperture in the LHC high-luminosity insertions at 6.5 TeV and β∗=40 cm. Previous aperture measurements in 2016 during commissioning had shown that the available aperture is at the edge of protection, and that the aperture bottleneck at β∗=40 cm in certain cases is found in the separation plane instead of in the crossing plane. Furthermore, the bottlenecks were consistently found in close to the upstream end of Q3 on the side of the incoming beam, and not in Q2 on the outgoing beam as expected from calculations. Therefore, this MD aimed at measuring IR1 and IR5 separately (at 6.5 TeV and β∗=40 cm, for 185 µrad half crossing angle), to further localize the bottlenecks longitudinally using newly installed BLMs, investigate the difference in aperture between Q2 and Q3, and to see if any aperture can be gained using special orbit bumps.

Assessing urban habitat quality based on specific leaf area and stomatal characteristics of Plantago lanceolata L

International Nuclear Information System (INIS)

Kardel, F.; Wuyts, K.; Babanezhad, M.; Vitharana, U.W.A.; Wuytack, T.; Potters, G.; Samson, R.

2010-01-01

This study has evaluated urban habitat quality by studying specific leaf area (SLA) and stomatal characteristics of the common herb Plantago lanceolata L. SLA and stomatal density, pore surface and resistance were measured at 169 locations in the city of Gent (Belgium), distributed over four land use classes, i.e., sub-urban green, urban green, urban and industry. SLA and stomatal density significantly increased from sub-urban green towards more urbanised land use classes, while the reverse was observed for stomatal pore surface. Stomatal resistance increased in the urban and industrial land use class in comparison with the (sub-) urban green, but differences between land use classes were less pronounced. Spatial distribution maps for these leaf characteristics showed a high spatial variation, related to differences in habitat quality within the city. Hence, stomatal density and stomatal pore surface are assumed to be potentially good bio-indicators for urban habitat quality. - Stomatal characteristics of Plantago lanceolata can be used for biomonitoring of urban habitat quality.

Guard Cell Signal Transduction Network: Advances in Understanding Abscisic Acid, CO2, and Ca2+ Signaling

KAUST Repository

Kim, Tae-Houn

2010-05-04

Stomatal pores are formed by pairs of specialized epidermal guard cells and serve as major gateways for both CO2 influx into plants from the atmosphere and transpirational water loss of plants. Because they regulate stomatal pore apertures via integration of both endogenous hormonal stimuli and environmental signals, guard cells have been highly developed as a model system to dissect the dynamics and mechanisms of plant-cell signaling. The stress hormone ABA and elevated levels of CO2 activate complex signaling pathways in guard cells that are mediated by kinases/phosphatases, secondary messengers, and ion channel regulation. Recent research in guard cells has led to a new hypothesis for how plants achieve specificity in intracellular calcium signaling: CO2 and ABA enhance (prime) the calcium sensitivity of downstream calcium-signaling mechanisms. Recent progress in identification of early stomatal signaling components are reviewed here, including ABA receptors and CO2-binding response proteins, as well as systems approaches that advance our understanding of guard cell-signaling mechanisms.

Guard Cell Signal Transduction Network: Advances in Understanding Abscisic Acid, CO2, and Ca2+ Signaling

KAUST Repository

Kim, Tae-Houn; Bö hmer, Maik; Hu, Honghong; Nishimura, Noriyuki; Schroeder, Julian I.

2010-01-01

Stomatal pores are formed by pairs of specialized epidermal guard cells and serve as major gateways for both CO2 influx into plants from the atmosphere and transpirational water loss of plants. Because they regulate stomatal pore apertures via integration of both endogenous hormonal stimuli and environmental signals, guard cells have been highly developed as a model system to dissect the dynamics and mechanisms of plant-cell signaling. The stress hormone ABA and elevated levels of CO2 activate complex signaling pathways in guard cells that are mediated by kinases/phosphatases, secondary messengers, and ion channel regulation. Recent research in guard cells has led to a new hypothesis for how plants achieve specificity in intracellular calcium signaling: CO2 and ABA enhance (prime) the calcium sensitivity of downstream calcium-signaling mechanisms. Recent progress in identification of early stomatal signaling components are reviewed here, including ABA receptors and CO2-binding response proteins, as well as systems approaches that advance our understanding of guard cell-signaling mechanisms.

Effects of sulfite and pH an abscisic acid (ABA) dependent transpiration and on stomatal opening

Energy Technology Data Exchange (ETDEWEB)

Kondo, N.; Maruta, I.; Sugahara, K.

1980-01-01

In rice, alday, wheat and tobacco (Nicotiana tabacum l. samsun and samsun nn) plants which contained large amounts of ABA, the transpiration rate decreased rapidly with 2 ppM SO/sub 2/ fumigation and reached 20 to 65% of the initial level after 5- to 30-min exposure depending on their ABAj contents. In the cases of broad bean and tobacco (n. Gutinosa l.) with low ABA contents, the rate slightly increased for 20 and 40 min, respectively, after the start of the fumigation and then decreased gradually. The transpiration rates of corn and sorghum, in spite of their extremely low ABA contents, pronouncedly decreased with SO/sub 2/ fumigation and reached 65 and 50%, respectively, of the initial levels after 40-min exposure. Foliar application of 0.04 N HCL to N. tacum l. samsun nn leaves remarkably depressed the transpiration rate, while the application of 0.04 m NA/sub 2/SO/sub 3/ decreased the rate only to the same level as water treatment. Foliar application of either HCL of Na/sub 2/SO/sub 3/ to N. glutinosa l. leaves exerted little change in the transpiration rate. When 10-4 m ABA was applied to broad bean leaves prior to HCl and Na/sub 2/SO/sub 3/ treatment, their transpiration rate was decreased by HCl, but not by Na/sub 2/SO/sub 3/ application. In sonicated epidermal strips peeled from broad bean leaves, Na/sub 2/SO/sub 3/ produced a slight increase in the stomatal aperture size in the absence of ABA, but showed no effect in the presence of ABA. The aperture size was identical in the pH range of 3.0 to 7.0 in the incubation medium. In the presence of ABA in the medium, the aperture size was small in the acidic region of pH with a minimal value at pH 4.0. ABA decreased the aperture size at concentrations above 10-9 m at pH 4.0 and 10-6 m at pH 7.0 in the medium. ABA uptake by epidermal strips was large in the acidic region, especially at pH 4.0.

Preventive effects of Ancer 20 injection against radiation stomatitis

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Naohiko; Nomura, Yasuya; Takano, Shinya (Showa Univ., Tokyo (Japan). School of Medicine) (and others)

1993-10-01

Ancer 20 was injected subcutaneously twice a day into 23 patients during the couse of radiation therapy for head and neck cancer, with the aim of preventing radiation stomatitis. Oral mucosa was assessed both subjectively and objectively, in addition to white blood cell counts. Objective findings of oral mucosa revealed grade I in 71%, grade II in 52%, grade III in 14%, and grade IV in 5%. The dose of irradiation needed to produce grade I in 50% was 22.8 Gy. Subjective findings revealed grade I in 67%, grade II in 33%, and grade III in 10%. Irradiation dose needed to produce grade I in 50% was 23.9 Gy. Mucosous damage was slight when the white blood cell count of 6,000/mm[sup 3] was maintained. According to the rate of leukopenia, this drug was effective in 86.4%. These findings showed that Ancer 20 injection is useful in maintaining white blood cell counts and in preventing radiation stomatitis associated with radiation therapy especially to the field of mucous membrane. There was inverse correlation between white blood cell counts and both the occurrence rate and degree of radiation stomatitis. It seemed necessary to maintain white blood cell counts to prevent radiation stomatitis. (N.K.).

Regulation of stomatal tropism and infection by light in Cercospora zeae-maydis: evidence for coordinated host/pathogen responses to photoperiod?

Directory of Open Access Journals (Sweden)

Hun Kim

2011-07-01

Full Text Available Cercospora zeae-maydis causes gray leaf spot of maize, which has become one of the most widespread and destructive diseases of maize in the world. C. zeae-maydis infects leaves through stomata, which is predicated on the ability of the pathogen to perceive stomata and reorient growth accordingly. In this study, the discovery that light was required for C. zeae-maydis to perceive stomata and infect leaves led to the identification of CRP1, a gene encoding a putative blue-light photoreceptor homologous to White Collar-1 (WC-1 of Neurospora crassa. Disrupting CRP1 via homologous recombination revealed roles in multiple aspects of pathogenesis, including tropism of hyphae to stomata, the formation of appressoria, conidiation, and the biosynthesis of cercosporin. CRP1 was also required for photoreactivation after lethal doses of UV exposure. Intriguingly, putative orthologs of CRP1 are central regulators of circadian clocks in other filamentous fungi, raising the possibility that C. zeae-maydis uses light as a key environmental input to coordinate pathogenesis with maize photoperiodic responses. This study identified a novel molecular mechanism underlying stomatal tropism in a foliar fungal pathogen, provides specific insight into how light regulates pathogenesis in C. zeae-maydis, and establishes a genetic framework for the molecular dissection of infection via stomata and the integration of host and pathogen responses to photoperiod.

Regulation of stomatal tropism and infection by light in Cercospora zeae-maydis: evidence for coordinated host/pathogen responses to photoperiod?

Science.gov (United States)

Kim, Hun; Ridenour, John B; Dunkle, Larry D; Bluhm, Burton H

2011-07-01

Cercospora zeae-maydis causes gray leaf spot of maize, which has become one of the most widespread and destructive diseases of maize in the world. C. zeae-maydis infects leaves through stomata, which is predicated on the ability of the pathogen to perceive stomata and reorient growth accordingly. In this study, the discovery that light was required for C. zeae-maydis to perceive stomata and infect leaves led to the identification of CRP1, a gene encoding a putative blue-light photoreceptor homologous to White Collar-1 (WC-1) of Neurospora crassa. Disrupting CRP1 via homologous recombination revealed roles in multiple aspects of pathogenesis, including tropism of hyphae to stomata, the formation of appressoria, conidiation, and the biosynthesis of cercosporin. CRP1 was also required for photoreactivation after lethal doses of UV exposure. Intriguingly, putative orthologs of CRP1 are central regulators of circadian clocks in other filamentous fungi, raising the possibility that C. zeae-maydis uses light as a key environmental input to coordinate pathogenesis with maize photoperiodic responses. This study identified a novel molecular mechanism underlying stomatal tropism in a foliar fungal pathogen, provides specific insight into how light regulates pathogenesis in C. zeae-maydis, and establishes a genetic framework for the molecular dissection of infection via stomata and the integration of host and pathogen responses to photoperiod.

Stomatal Conductance, Plant Hydraulics, and Multilayer Canopies: A New Paradigm for Earth System Models or Unnecessary Uncertainty

Science.gov (United States)

Bonan, G. B.

2016-12-01

Soil moisture stress is a key regulator of canopy transpiration, the surface energy budget, and land-atmosphere coupling. Many land surface models used in Earth system models have an ad-hoc parameterization of soil moisture stress that decreases stomatal conductance with soil drying. Parameterization of soil moisture stress from more fundamental principles of plant hydrodynamics is a key research frontier for land surface models. While the biophysical and physiological foundations of such parameterizations are well-known, their best implementation in land surface models is less clear. Land surface models utilize a big-leaf canopy parameterization (or two big-leaves to represent the sunlit and shaded canopy) without vertical gradients in the canopy. However, there are strong biometeorological and physiological gradients in plant canopies. Are these gradients necessary to resolve? Here, I describe a vertically-resolved, multilayer canopy model that calculates leaf temperature and energy fluxes, photosynthesis, stomatal conductance, and leaf water potential at each level in the canopy. In this model, midday leaf water stress manifests in the upper canopy layers, which receive high amounts of solar radiation, have high leaf nitrogen and photosynthetic capacity, and have high stomatal conductance and transpiration rates (in the absence of leaf water stress). Lower levels in the canopy become water stressed in response to longer-term soil moisture drying. I examine the role of vertical gradients in the canopy microclimate (solar radiation, air temperature, vapor pressure, wind speed), structure (leaf area density), and physiology (leaf nitrogen, photosynthetic capacity, stomatal conductance) in determining above canopy fluxes and gradients of transpiration and leaf water potential within the canopy.

APT: Aperture Photometry Tool

Science.gov (United States)

Laher, Russ

2012-08-01

Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It has a graphical user interface (GUI) which allows the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. Mouse-clicking on a source in the displayed image draws a circular or elliptical aperture and sky annulus around the source and computes the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs, including image histogram, and aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has functions for customizing calculations, including outlier rejection, pixel “picking” and “zapping,” and a selection of source and sky models. The radial-profile-interpolation source model, accessed via the radial-profile-plot panel, allows recovery of source intensity from pixels with missing data and can be especially beneficial in crowded fields.

Carbon and hydrogen isotopic effects of stomatal density in Arabidopsis thaliana

Science.gov (United States)

Lee, Hyejung; Feakins, Sarah J.; Sternberg, Leonel da S. L.

2016-04-01

Stomata are key gateways mediating carbon uptake and water loss from plants. Varied stomatal densities in fossil leaves raise the possibility that isotope effects associated with the openness of exchange may have mediated plant wax biomarker isotopic proxies for paleovegetation and paleoclimate in the geological record. Here we use Arabidopsis thaliana, a widely used model organism, to provide the first controlled tests of stomatal density on carbon and hydrogen isotopic compositions of cuticular waxes. Laboratory grown wildtype and mutants with suppressed and overexpressed stomatal densities allow us to directly test the isotope effects of stomatal densities independent of most other environmental or biological variables. Hydrogen isotope (D/H) measurements of both plant waters and plant wax n-alkanes allow us to directly constrain the isotopic effects of leaf water isotopic enrichment via transpiration and biosynthetic fractionations, which together determine the net fractionation between irrigation water and n-alkane hydrogen isotopic composition. We also measure carbon isotopic fractionations of n-alkanes and bulk leaf tissue associated with different stomatal densities. We find offsets of +15‰ for δD and -3‰ for δ13C for the overexpressed mutant compared to the suppressed mutant. Since the range of stomatal densities expressed is comparable to that found in extant plants and the Cenozoic fossil record, the results allow us to consider the magnitude of isotope effects that may be incurred by these plant adaptive responses. This study highlights the potential of genetic mutants to isolate individual isotope effects and add to our fundamental understanding of how genetics and physiology influence plant biochemicals including plant wax biomarkers.

Mastering Apple Aperture

CERN Document Server

Fitzgerald, Thomas

2013-01-01

Written in a conversational style, the author will share his knowledge on advanced Aperture topics with detailed discussions of advanced topics, the theory behind some of those topics and lots of hints and tips for ways to improve your workflow.Photographer's who have a basic understanding of Aperture

Stomatal Function Requires Pectin De-methyl-esterification of the Guard Cell Wall.

Science.gov (United States)

Amsbury, Sam; Hunt, Lee; Elhaddad, Nagat; Baillie, Alice; Lundgren, Marjorie; Verhertbruggen, Yves; Scheller, Henrik V; Knox, J Paul; Fleming, Andrew J; Gray, Julie E

2016-11-07

Stomatal opening and closure depends on changes in turgor pressure acting within guard cells to alter cell shape [1]. The extent of these shape changes is limited by the mechanical properties of the cells, which will be largely dependent on the structure of the cell walls. Although it has long been observed that guard cells are anisotropic due to differential thickening and the orientation of cellulose microfibrils [2], our understanding of the composition of the cell wall that allows them to undergo repeated swelling and deflation remains surprisingly poor. Here, we show that the walls of guard cells are rich in un-esterified pectins. We identify a pectin methylesterase gene, PME6, which is highly expressed in guard cells and required for stomatal function. pme6-1 mutant guard cells have walls enriched in methyl-esterified pectin and show a decreased dynamic range in response to triggers of stomatal opening/closure, including elevated osmoticum, suggesting that abrogation of stomatal function reflects a mechanical change in the guard cell wall. Altered stomatal function leads to increased conductance and evaporative cooling, as well as decreased plant growth. The growth defect of the pme6-1 mutant is rescued by maintaining the plants in elevated CO 2 , substantiating gas exchange analyses, indicating that the mutant stomata can bestow an improved assimilation rate. Restoration of PME6 rescues guard cell wall pectin methyl-esterification status, stomatal function, and plant growth. Our results establish a link between gene expression in guard cells and their cell wall properties, with a corresponding effect on stomatal function and plant physiology. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Stomatal cell wall composition: distinctive structural patterns associated with different phylogenetic groups.

Science.gov (United States)

Shtein, Ilana; Shelef, Yaniv; Marom, Ziv; Zelinger, Einat; Schwartz, Amnon; Popper, Zoë A; Bar-On, Benny; Harpaz-Saad, Smadar

2017-04-01

Stomatal morphology and function have remained largely conserved throughout ∼400 million years of plant evolution. However, plant cell wall composition has evolved and changed. Here stomatal cell wall composition was investigated in different vascular plant groups in attempt to understand their possible effect on stomatal function. A renewed look at stomatal cell walls was attempted utilizing digitalized polar microscopy, confocal microscopy, histology and a numerical finite-elements simulation. The six species of vascular plants chosen for this study cover a broad structural, ecophysiological and evolutionary spectrum: ferns ( Asplenium nidus and Platycerium bifurcatum ) and angiosperms ( Arabidopsis thaliana and Commelina erecta ) with kidney-shaped stomata, and grasses (angiosperms, family Poaceae) with dumbbell-shaped stomata ( Sorghum bicolor and Triticum aestivum ). Three distinct patterns of cellulose crystallinity in stomatal cell walls were observed: Type I (kidney-shaped stomata, ferns), Type II (kidney-shaped stomata, angiosperms) and Type III (dumbbell-shaped stomata, grasses). The different stomatal cell wall attributes investigated (cellulose crystallinity, pectins, lignin, phenolics) exhibited taxon-specific patterns, with reciprocal substitution of structural elements in the end-walls of kidney-shaped stomata. According to a numerical bio-mechanical model, the end walls of kidney-shaped stomata develop the highest stresses during opening. The data presented demonstrate for the first time the existence of distinct spatial patterns of varying cellulose crystallinity in guard cell walls. It is also highly intriguing that in angiosperms crystalline cellulose appears to have replaced lignin that occurs in the stomatal end-walls of ferns serving a similar wall strengthening function. Such taxon-specific spatial patterns of cell wall components could imply different biomechanical functions, which in turn could be a consequence of differences in

Aperture area measurement facility

Data.gov (United States)

Federal Laboratory Consortium — NIST has established an absolute aperture area measurement facility for circular and near-circular apertures use in radiometric instruments. The facility consists of...

The alpha-subunit of the Arabidopsis heterotrimeric G protein, GPA1, is a regulator of transpiration efficiency.

Science.gov (United States)

Nilson, Sarah E; Assmann, Sarah M

2010-04-01

Land plants must balance CO2 assimilation with transpiration in order to minimize drought stress and maximize their reproductive success. The ratio of assimilation to transpiration is called transpiration efficiency (TE). TE is under genetic control, although only one specific gene, ERECTA, has been shown to regulate TE. We have found that the alpha-subunit of the heterotrimeric G protein in Arabidopsis (Arabidopsis thaliana), GPA1, is a regulator of TE. gpa1 mutants, despite having guard cells that are hyposensitive to abscisic acid-induced inhibition of stomatal opening, have increased TE under ample water and drought stress conditions and when treated with exogenous abscisic acid. Leaf-level gas-exchange analysis shows that gpa1 mutants have wild-type assimilation versus internal CO2 concentration responses but exhibit reduced stomatal conductance compared with ecotype Columbia at ambient and below-ambient internal CO2 concentrations. The increased TE and reduced whole leaf stomatal conductance of gpa1 can be primarily attributed to stomatal density, which is reduced in gpa1 mutants. GPA1 regulates stomatal density via the control of epidermal cell size and stomata formation. GPA1 promoter::beta-glucuronidase lines indicate that the GPA1 promoter is active in the stomatal cell lineage, further supporting a function for GPA1 in stomatal development in true leaves.

Overexpression of StNF-YB3.1 reduces photosynthetic capacity and tuber production, and promotes ABA-mediated stomatal closure in potato (Solanum tuberosum L.).

Science.gov (United States)

Xuanyuan, Guochao; Lu, Congming; Zhang, Ruofang; Jiang, Jiming

2017-08-01

Nuclear factor Y (NF-Y) is one of the most ubiquitous transcription factors (TFs), comprising NF-YA, NF-YB and NF-YC subunits, and has been identified and reported in various aspects of development for plants and animals. In this work, StNF-YB3.1, a putative potato NF-YB subunit encoding gene, was isolated from Solanum tuberosum by rapid amplification of cDNA ends (RACE). Overexpression of StNF-YB3.1 in potato (cv. Atlantic) resulted in accelerated onset of flowering, and significant increase in leaf chlorophyll content in field trials. However, transgenic potato plants overexpressing StNF-YB3.1 (OEYB3.1) showed significant decreases in photosynthetic rate and stomatal conductance both at tuber initiation and bulking stages. OEYB3.1 lines were associated with significantly fewer tuber numbers and yield reduction. Guard cell size and stomatal density were not changed in OEYB3.1 plants, whereas ABA-mediated stomatal closure was accelerated compared to that of wild type plants because of the up-regulation of genes for ABA signaling, such as StCPK10-like, StSnRK2.6/OST1-like, StSnRK2.7-like and StSLAC1-like. We speculate that the acceleration of stomatal closure was a possible reason for the significantly decreased stomatal conductance and photosynthetic rate. Copyright © 2017 Elsevier B.V. All rights reserved.

Tissue Harmonic Synthetic Aperture Imaging

DEFF Research Database (Denmark)

Rasmussen, Joachim

The main purpose of this PhD project is to develop an ultrasonic method for tissue harmonic synthetic aperture imaging. The motivation is to advance the field of synthetic aperture imaging in ultrasound, which has shown great potentials in the clinic. Suggestions for synthetic aperture tissue...... system complexity compared to conventional synthetic aperture techniques. In this project, SASB is sought combined with a pulse inversion technique for 2nd harmonic tissue harmonic imaging. The advantages in tissue harmonic imaging (THI) are expected to further improve the image quality of SASB...

Stomatal vs. genome size in angiosperms: the somatic tail wagging the genomic dog?

Science.gov (United States)

Hodgson, J G; Sharafi, M; Jalili, A; Díaz, S; Montserrat-Martí, G; Palmer, C; Cerabolini, B; Pierce, S; Hamzehee, B; Asri, Y; Jamzad, Z; Wilson, P; Raven, J A; Band, S R; Basconcelo, S; Bogard, A; Carter, G; Charles, M; Castro-Díez, P; Cornelissen, J H C; Funes, G; Jones, G; Khoshnevis, M; Pérez-Harguindeguy, N; Pérez-Rontomé, M C; Shirvany, F A; Vendramini, F; Yazdani, S; Abbas-Azimi, R; Boustani, S; Dehghan, M; Guerrero-Campo, J; Hynd, A; Kowsary, E; Kazemi-Saeed, F; Siavash, B; Villar-Salvador, P; Craigie, R; Naqinezhad, A; Romo-Díez, A; de Torres Espuny, L; Simmons, E

2010-04-01

Genome size is a function, and the product, of cell volume. As such it is contingent on ecological circumstance. The nature of 'this ecological circumstance' is, however, hotly debated. Here, we investigate for angiosperms whether stomatal size may be this 'missing link': the primary determinant of genome size. Stomata are crucial for photosynthesis and their size affects functional efficiency. Stomatal and leaf characteristics were measured for 1442 species from Argentina, Iran, Spain and the UK and, using PCA, some emergent ecological and taxonomic patterns identified. Subsequently, an assessment of the relationship between genome-size values obtained from the Plant DNA C-values database and measurements of stomatal size was carried out. Stomatal size is an ecologically important attribute. It varies with life-history (woody species < herbaceous species < vernal geophytes) and contributes to ecologically and physiologically important axes of leaf specialization. Moreover, it is positively correlated with genome size across a wide range of major taxa. Stomatal size predicts genome size within angiosperms. Correlation is not, however, proof of causality and here our interpretation is hampered by unexpected deficiencies in the scientific literature. Firstly, there are discrepancies between our own observations and established ideas about the ecological significance of stomatal size; very large stomata, theoretically facilitating photosynthesis in deep shade, were, in this study (and in other studies), primarily associated with vernal geophytes of unshaded habitats. Secondly, the lower size limit at which stomata can function efficiently, and the ecological circumstances under which these minute stomata might occur, have not been satisfactorally resolved. Thus, our hypothesis, that the optimization of stomatal size for functional efficiency is a major ecological determinant of genome size, remains unproven.

Survey of coded aperture imaging

International Nuclear Information System (INIS)

Barrett, H.H.

1975-01-01

The basic principle and limitations of coded aperture imaging for x-ray and gamma cameras are discussed. Current trends include (1) use of time varying apertures, (2) use of ''dilute'' apertures with transmission much less than 50%, and (3) attempts to derive transverse tomographic sections, unblurred by other planes, from coded images

A comparison of two stomatal conductance models for ozone flux modelling using data from two Brassica species

International Nuclear Information System (INIS)

Op de Beeck, M.; De Bock, M.; Vandermeiren, K.; Temmerman, L. de; Ceulemans, R.

2010-01-01

In this study we tested and compared a multiplicative stomatal model and a coupled semi-empirical stomatal-photosynthesis model in their ability to predict stomatal conductance to ozone (g st ) using leaf-level data from oilseed rape (Brassica napus L.) and broccoli (Brassica oleracea L. var. italica Plenck). For oilseed rape, the multiplicative model and the coupled model were able to explain 72% and 73% of the observed g st variance, respectively. For broccoli, the models were able to explain 53% and 51% of the observed g st variance, respectively. These results support the coupled semi-empirical stomatal-photosynthesis model as a valid alternative to the multiplicative stomatal model for O 3 flux modelling, in terms of predictive performance. - A multiplicative stomatal model and a coupled semi-empirical stomatal-photosynthesis model performed equally well when tested against leaf-level data for oilseed rape and broccoli.

Vesicular stomatitis forecasting based on Google Trends.

Science.gov (United States)

Wang, JianYing; Zhang, Tong; Lu, Yi; Zhou, GuangYa; Chen, Qin; Niu, Bing

2018-01-01

Vesicular stomatitis (VS) is an important viral disease of livestock. The main feature of VS is irregular blisters that occur on the lips, tongue, oral mucosa, hoof crown and nipple. Humans can also be infected with vesicular stomatitis and develop meningitis. This study analyses 2014 American VS outbreaks in order to accurately predict vesicular stomatitis outbreak trends. American VS outbreaks data were collected from OIE. The data for VS keywords were obtained by inputting 24 disease-related keywords into Google Trends. After calculating the Pearson and Spearman correlation coefficients, it was found that there was a relationship between outbreaks and keywords derived from Google Trends. Finally, the predicted model was constructed based on qualitative classification and quantitative regression. For the regression model, the Pearson correlation coefficients between the predicted outbreaks and actual outbreaks are 0.953 and 0.948, respectively. For the qualitative classification model, we constructed five classification predictive models and chose the best classification predictive model as the result. The results showed, SN (sensitivity), SP (specificity) and ACC (prediction accuracy) values of the best classification predictive model are 78.52%,72.5% and 77.14%, respectively. This study applied Google search data to construct a qualitative classification model and a quantitative regression model. The results show that the method is effective and that these two models obtain more accurate forecast.

Vesicular stomatitis forecasting based on Google Trends

Science.gov (United States)

Lu, Yi; Zhou, GuangYa; Chen, Qin

2018-01-01

Background Vesicular stomatitis (VS) is an important viral disease of livestock. The main feature of VS is irregular blisters that occur on the lips, tongue, oral mucosa, hoof crown and nipple. Humans can also be infected with vesicular stomatitis and develop meningitis. This study analyses 2014 American VS outbreaks in order to accurately predict vesicular stomatitis outbreak trends. Methods American VS outbreaks data were collected from OIE. The data for VS keywords were obtained by inputting 24 disease-related keywords into Google Trends. After calculating the Pearson and Spearman correlation coefficients, it was found that there was a relationship between outbreaks and keywords derived from Google Trends. Finally, the predicted model was constructed based on qualitative classification and quantitative regression. Results For the regression model, the Pearson correlation coefficients between the predicted outbreaks and actual outbreaks are 0.953 and 0.948, respectively. For the qualitative classification model, we constructed five classification predictive models and chose the best classification predictive model as the result. The results showed, SN (sensitivity), SP (specificity) and ACC (prediction accuracy) values of the best classification predictive model are 78.52%,72.5% and 77.14%, respectively. Conclusion This study applied Google search data to construct a qualitative classification model and a quantitative regression model. The results show that the method is effective and that these two models obtain more accurate forecast. PMID:29385198

Vesicular stomatitis forecasting based on Google Trends.

Directory of Open Access Journals (Sweden)

JianYing Wang

Full Text Available Vesicular stomatitis (VS is an important viral disease of livestock. The main feature of VS is irregular blisters that occur on the lips, tongue, oral mucosa, hoof crown and nipple. Humans can also be infected with vesicular stomatitis and develop meningitis. This study analyses 2014 American VS outbreaks in order to accurately predict vesicular stomatitis outbreak trends.American VS outbreaks data were collected from OIE. The data for VS keywords were obtained by inputting 24 disease-related keywords into Google Trends. After calculating the Pearson and Spearman correlation coefficients, it was found that there was a relationship between outbreaks and keywords derived from Google Trends. Finally, the predicted model was constructed based on qualitative classification and quantitative regression.For the regression model, the Pearson correlation coefficients between the predicted outbreaks and actual outbreaks are 0.953 and 0.948, respectively. For the qualitative classification model, we constructed five classification predictive models and chose the best classification predictive model as the result. The results showed, SN (sensitivity, SP (specificity and ACC (prediction accuracy values of the best classification predictive model are 78.52%,72.5% and 77.14%, respectively.This study applied Google search data to construct a qualitative classification model and a quantitative regression model. The results show that the method is effective and that these two models obtain more accurate forecast.

A steady-state stomatal model of balanced leaf gas exchange, hydraulics and maximal source-sink flux.

Science.gov (United States)

Hölttä, Teemu; Lintunen, Anna; Chan, Tommy; Mäkelä, Annikki; Nikinmaa, Eero

2017-07-01

Trees must simultaneously balance their CO2 uptake rate via stomata, photosynthesis, the transport rate of sugars and rate of sugar utilization in sinks while maintaining a favourable water and carbon balance. We demonstrate using a numerical model that it is possible to understand stomatal functioning from the viewpoint of maximizing the simultaneous photosynthetic production, phloem transport and sink sugar utilization rate under the limitation that the transpiration-driven hydrostatic pressure gradient sets for those processes. A key feature in our model is that non-stomatal limitations to photosynthesis increase with decreasing leaf water potential and/or increasing leaf sugar concentration and are thus coupled to stomatal conductance. Maximizing the photosynthetic production rate using a numerical steady-state model leads to stomatal behaviour that is able to reproduce the well-known trends of stomatal behaviour in response to, e.g., light, vapour concentration difference, ambient CO2 concentration, soil water status, sink strength and xylem and phloem hydraulic conductance. We show that our results for stomatal behaviour are very similar to the solutions given by the earlier models of stomatal conductance derived solely from gas exchange considerations. Our modelling results also demonstrate how the 'marginal cost of water' in the unified stomatal conductance model and the optimal stomatal model could be related to plant structural and physiological traits, most importantly, the soil-to-leaf hydraulic conductance and soil moisture. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Three dimensional fracture aperture and porosity distribution using computerized tomography

Science.gov (United States)

Wenning, Q.; Madonna, C.; Joss, L.; Pini, R.

2017-12-01

A wide range of geologic processes and geo-engineered applications are governed by coupled hydromechanical properties in the subsurface. In geothermal energy reservoirs, quantifying the rate of heat transfer is directly linked with the transport properties of fractures, underscoring the importance of fracture aperture characterization for achieving optimal heat production. In this context, coupled core-flooding experiments with non-invasive imaging techniques (e.g., X-Ray Computed Tomography - X-Ray CT) provide a powerful method to make observations of these properties under representative geologic conditions. This study focuses on quantifying fracture aperture distribution in a fractured westerly granite core by using a recently developed calibration-free method [Huo et al., 2016]. Porosity is also estimated with the X-ray saturation technique using helium and krypton gases as saturating fluids, chosen for their high transmissibility and high CT contrast [e.g., Vega et al., 2014]. The westerly granite sample (diameter: 5 cm, length: 10 cm) with a single through-going rough-walled fracture was mounted in a high-pressure aluminum core-holder and placed inside a medical CT scanner for imaging. During scanning the pore fluid pressure was undrained and constant, and the confining pressure was regulated to have the desired effective pressure (0.5, 5, 7 and 10 MPa) under loading and unloading conditions. 3D reconstructions of the sample have been prepared in terms of fracture aperture and porosity at a maximum resolution of (0.24×0.24×1) mm3. Fracture aperture maps obtained independently using helium and krypton for the whole core depict a similar heterogeneous aperture field, which is also dependent on confining pressure. Estimates of the average hydraulic aperture from CT scans are in quantitative agreement with results from fluid flow experiments. However, the latter lack of the level of observational detail achieved through imaging, which further evidence the

Aperture averaging in strong oceanic turbulence

Science.gov (United States)

Gökçe, Muhsin Caner; Baykal, Yahya

2018-04-01

Receiver aperture averaging technique is employed in underwater wireless optical communication (UWOC) systems to mitigate the effects of oceanic turbulence, thus to improve the system performance. The irradiance flux variance is a measure of the intensity fluctuations on a lens of the receiver aperture. Using the modified Rytov theory which uses the small-scale and large-scale spatial filters, and our previously presented expression that shows the atmospheric structure constant in terms of oceanic turbulence parameters, we evaluate the irradiance flux variance and the aperture averaging factor of a spherical wave in strong oceanic turbulence. Irradiance flux variance variations are examined versus the oceanic turbulence parameters and the receiver aperture diameter are examined in strong oceanic turbulence. Also, the effect of the receiver aperture diameter on the aperture averaging factor is presented in strong oceanic turbulence.

GID1 modulates stomatal response and submergence tolerance involving abscisic acid and gibberellic acid signaling in rice.

Science.gov (United States)

Du, Hao; Chang, Yu; Huang, Fei; Xiong, Lizhong

2015-11-01

Plant responses to abiotic stresses are coordinated by arrays of growth and developmental programs. Gibberellic acid (GA) and abscisic acid (ABA) play critical roles in the developmental programs and environmental responses, respectively, through complex signaling and metabolism networks. However, crosstalk between the two phytohormones in stress responses remains largely unknown. In this study, we report that GIBBERELLIN-INSENSITIVE DWARF 1 (GID1), a soluble receptor for GA, regulates stomatal development and patterning in rice (Oryza sativa L.). The gid1 mutant showed impaired biosynthesis of endogenous ABA under drought stress conditions, but it exhibited enhanced sensitivity to exogenous ABA. Scanning electron microscope and infrared thermal image analysis indicated an increase in the stomatal conductance in the gid1 mutant under drought conditions. Interestingly, the gid1 mutant had increased levels of chlorophyll and carbohydrates under submergence conditions, and showed enhanced reactive oxygen species (ROS)-scavenging ability and submergence tolerance compared with the wild-type. Further analyses suggested that the function of GID1 in submergence responses is partially dependent on ABA, and GA signaling by GID1 is involved in submergence tolerance by modulating carbohydrate consumption. Taken together, these findings suggest GID1 plays distinct roles in stomatal response and submergence tolerance through both the ABA and GA signaling pathways in rice. © 2014 Institute of Botany, Chinese Academy of Sciences.

Virus-induced down-regulation of GmERA1A and GmERA1B genes enhances the stomatal response to abscisic acid and drought resistance in soybean.

Directory of Open Access Journals (Sweden)

Takuya Ogata

Full Text Available Drought is a major threat to global soybean production. The limited transformation potential and polyploid nature of soybean have hindered functional analysis of soybean genes. Previous research has implicated farnesylation in the plant's response to abscisic acid (ABA and drought tolerance. We therefore used virus-induced gene silencing (VIGS to evaluate farnesyltransferase genes, GmERA1A and GmERA1B (Glycine max Enhanced Response to ABA1-A and -B, as potential targets for increasing drought resistance in soybean. Apple latent spherical virus (ALSV-mediated GmERA1-down-regulated soybean leaves displayed an enhanced stomatal response to ABA and reduced water loss and wilting under dehydration conditions, suggesting that GmERA1A and GmERA1B negatively regulate ABA signaling in soybean guard cells. The findings provide evidence that the ALSV-VIGS system, which bypasses the need to generate transgenic plants, is a useful tool for analyzing gene function using only a single down-regulated leaf. Thus, the ALSV-VIGS system could constitute part of a next-generation molecular breeding pipeline to accelerate drought resistance breeding in soybean.

Les caractéristiques des stomates des feuilles de Ficus benjamina L ...

African Journals Online (AJOL)

Objective: The main objective of this study is to assess the potential of Ficus benjamina stomata to be used as indicators of local air pollution. Methodology: Stomatal prints were taken from the species of study in the vicinity of roads, in residential and industrial areas and parks. Density, pore surface and stomatal resistance ...

The LHC dynamic aperture

CERN Document Server

Koutchouk, Jean-Pierre

1999-01-01

In 1996, the expected field errors in the dipoles and quadrupoles yielded a long-term dynamic aperture of some 8sigma at injection. The target was set to 12sigma to account for the limitations of our model (imperfections and dynamics). From scaling laws and tracking, a specification for the field imperfections yielding the target dynamic aperture was deduced. The gap between specification and expected errors is being bridged by i) an improvement of the dipole field quality, ii) a balance between geometric and persistent current errors, iii) additional correction circuits (a3 ,b4 ). With the goal in view, the emphasis has now turned to the sensitivity of the dynamic aperture to the optical parameters.The distortion of the dynamics at the lower amplitudes effectively reached by the particles is minimized by optimizing the distribution of the betatron phase advance. At collision energy, the dynamic aperture is limited by the field imperfections of the low-beta triplets, enhanced by the crossing angle. With corre...

OsPRX2 contributes to stomatal closure and improves potassium deficiency tolerance in rice.

Science.gov (United States)

Mao, Xiaohui; Zheng, Yanmei; Xiao, Kaizhuan; Wei, Yidong; Zhu, Yongsheng; Cai, Qiuhua; Chen, Liping; Xie, Huaan; Zhang, Jianfu

2018-01-01

Peroxiredoxins (Prxs) which are thiol-based peroxidases have been implicated in the toxic reduction and intracellular concentration regulation of hydrogen peroxide. In Arabidopsis thaliana At2-CysPrxB (At5g06290) has been demonstrated to be essential in maintaining the water-water cycle for proper H 2 O 2 scavenging. Although the mechanisms of 2-Cys Prxs have been extensively studied in Arabidopsis thaliana, the function of 2-Cys Prxs in rice is unclear. In this study, a rice homologue gene of At2-CysPrxB, OsPRX2 was investigated aiming to characterize the effect of 2-Cys Prxs on the K + -deficiency tolerance in rice. We found that OsPRX2 was localized in the chloroplast. Overexpressed OsPRX2 causes the stomatal closing and K + -deficiency tolerance increasing, while knockout of OsPRX2 lead to serious defects in leaves phenotype and the stomatal opening under the K + -deficiency tolerance. Detection of K + accumulation, antioxidant activity of transgenic plants under the starvation of potassium, further confirmed that OsPRX2 is a potential target for engineering plants with improved potassium deficiency tolerance. Copyright © 2017 Elsevier Inc. All rights reserved.

Drought limitations to leaf-level gas exchange: results from a model linking stomatal optimization and cohesion-tension theory.

Science.gov (United States)

Novick, Kimberly A; Miniat, Chelcy F; Vose, James M

2016-03-01

We merge concepts from stomatal optimization theory and cohesion-tension theory to examine the dynamics of three mechanisms that are potentially limiting to leaf-level gas exchange in trees during drought: (1) a 'demand limitation' driven by an assumption of optimal stomatal functioning; (2) 'hydraulic limitation' of water movement from the roots to the leaves; and (3) 'non-stomatal' limitations imposed by declining leaf water status within the leaf. Model results suggest that species-specific 'economics' of stomatal behaviour may play an important role in differentiating species along the continuum of isohydric to anisohydric behaviour; specifically, we show that non-stomatal and demand limitations may reduce stomatal conductance and increase leaf water potential, promoting wide safety margins characteristic of isohydric species. We used model results to develop a diagnostic framework to identify the most likely limiting mechanism to stomatal functioning during drought and showed that many of those features were commonly observed in field observations of tree water use dynamics. Direct comparisons of modelled and measured stomatal conductance further indicated that non-stomatal and demand limitations reproduced observed patterns of tree water use well for an isohydric species but that a hydraulic limitation likely applies in the case of an anisohydric species. Published 2015. This article is a US Government work and is in the public domain in the USA.

Contrasting responses of leaf stomatal characteristics to climate change: a considerable challenge to predict carbon and water cycles.

Science.gov (United States)

Yan, Weiming; Zhong, Yangquanwei; Shangguan, Zhouping

2017-09-01

Stomata control the cycling of water and carbon between plants and the atmosphere; however, no consistent conclusions have been drawn regarding the response of stomatal frequency to climate change. Here, we conducted a meta-analysis of 1854 globally obtained data series to determine the response of stomatal frequency to climate change, which including four plant life forms (over 900 species), at altitudes ranging from 0 to 4500 m and over a time span of more than one hundred thousand years. Stomatal frequency decreased with increasing CO 2 concentration and increased with elevated temperature and drought stress; it was also dependent on the species and experimental conditions. The response of stomatal frequency to climate change showed a trade-off between stomatal control strategies and environmental factors, such as the CO 2 concentration, temperature, and soil water availability. Moreover, threshold effects of elevated CO 2 and temperature on stomatal frequency were detected, indicating that the response of stomatal density to increasing CO 2 concentration will decrease over the next few years. The results also suggested that the stomatal index may be more reliable than stomatal density for determination of the historic CO 2 concentration. Our findings indicate that the contrasting responses of stomata to climate change bring a considerable challenge in predicting future water and carbon cycles. © 2017 John Wiley & Sons Ltd.

Nitric oxide in guard cells as an important secondary messenger during stomatal closure

Directory of Open Access Journals (Sweden)

Gunja eGayatri

2013-10-01

Full Text Available he modulation of guard cell function is the basis of stomatal closure, essential for optimizing water use and CO2 uptake by leaves. Nitric oxide (NO in guard cells plays a very important role as a secondary messenger during stomatal closure induced by effectors, including hormones. For example, exposure to abscisic acid (ABA triggers a marked increase in NO of guard cells, well before stomatal closure. In guard cells of multiple species, like Arabidopsis, Vicia and pea, exposure to ABA or methyl jasmonate or even microbial elicitors (e.g. chitosan induces production of NO as well as reactive oxygen species (ROS. The role of NO in stomatal closure has been confirmed by using NO donors (e.g. SNP and NO scavengers (like cPTIO and inhibitors of NOS (L-NAME or NR (tungstate. Two enzymes: a L-NAME-sensitive, nitric oxide synthase (NOS-like enzyme and a tungstate-sensitive nitrate reductase (NR, can mediate ABA-induced NO rise in guard cells. However, the existence of true NOS in plant tissues and its role in guard cell NO-production are still a matter of intense debate. Guard cell signal transduction leading to stomatal closure involves the participation of several components, besides NO, such as cytosolic pH, ROS, free Ca2+ and phospholipids. Use of fluorescent dyes has revealed that the rise in NO of guard cells occurs after the increase in cytoplasmic pH and ROS. The rise in NO causes an elevation in cytosolic free Ca2+ and promotes the efflux of cations as well as anions from guard cells. Stomatal guard cells have become a model system to study the signalling cascade mechanisms in plants, particularly with NO as a dominant component. The interrelationships and interactions of NO with cytosolic pH, ROS, and free Ca2+ are quite complex and need further detailed examination. While assessing critically the available literature, the present review projects possible areas of further work related to NO-action in stomatal guard cells.

Large aperture optical switching devices

International Nuclear Information System (INIS)

Goldhar, J.; Henesian, M.A.

1983-01-01

We have developed a new approach to constructing large aperture optical switches for next generation inertial confinement fusion lasers. A transparent plasma electrode formed in low pressure ionized gas acts as a conductive coating to allow the uniform charging of the optical faces of an electro-optic material. In this manner large electric fields can be applied longitudinally to large aperture, high aspect ratio Pockels cells. We propose a four-electrode geometry to create the necessary high conductivity plasma sheets, and have demonstrated fast (less than 10 nsec) switching in a 5x5 cm aperture KD*P Pockels cell with such a design. Detaid modelling of Pockels cell performance with plasma electrodes has been carried out for 15 and 30 cm aperture designs

Constitutive activation of a plasma membrane H+-ATPase prevents abscisic acid-mediated stomatal closure

Science.gov (United States)

Merlot, Sylvain; Leonhardt, Nathalie; Fenzi, Francesca; Valon, Christiane; Costa, Miguel; Piette, Laurie; Vavasseur, Alain; Genty, Bernard; Boivin, Karine; Müller, Axel; Giraudat, Jérôme; Leung, Jeffrey

2007-01-01

Light activates proton (H+)-ATPases in guard cells, to drive hyperpolarization of the plasma membrane to initiate stomatal opening, allowing diffusion of ambient CO2 to photosynthetic tissues. Light to darkness transition, high CO2 levels and the stress hormone abscisic acid (ABA) promote stomatal closing. The overall H+-ATPase activity is diminished by ABA treatments, but the significance of this phenomenon in relationship to stomatal closure is still debated. We report two dominant mutations in the OPEN STOMATA2 (OST2) locus of Arabidopsis that completely abolish stomatal response to ABA, but importantly, to a much lesser extent the responses to CO2 and darkness. The OST2 gene encodes the major plasma membrane H+-ATPase AHA1, and both mutations cause constitutive activity of this pump, leading to necrotic lesions. H+-ATPases have been traditionally assumed to be general endpoints of all signaling pathways affecting membrane polarization and transport. Our results provide evidence that AHA1 is a distinct component of an ABA-directed signaling pathway, and that dynamic downregulation of this pump during drought is an essential step in membrane depolarization to initiate stomatal closure. PMID:17557075

Effects of a Heat Wave on Nocturnal Stomatal Conductance in Eucalyptus camaldulensis

Directory of Open Access Journals (Sweden)

Víctor Resco de Dios

2018-06-01

Full Text Available Nocturnal transpiration constitutes a significant yet poorly understood component of the global water cycle. Modeling nocturnal transpiration has been complicated by recent findings showing that stomata respond differently to environmental drivers over day- vs. night-time periods. Here, we propose that nocturnal stomatal conductance depends on antecedent daytime conditions. We tested this hypothesis across six genotypes of Eucalyptus camaldulensis Dehnh. growing under different CO2 concentrations (ambient vs. elevated and exposed to contrasting temperatures (ambient vs. heat wave for four days prior to the night of measurements, when all plants experienced ambient temperature conditions. We observed significant effects after the heat wave that led to 36% reductions in nocturnal stomatal conductance. The response was partly driven by changes in daytime stomatal behavior but additional factors may have come into play. We also observed significant differences in response to the heat wave across genotypes, likely driven by local adaptation to their climate of origin, but CO2 played no effect. Stomatal models may need to incorporate the role of antecedent effects to improve projections particularly after drastic changes in the environment such as heat waves.

Stomatal response of Pinus sylvestriformis to elevated CO2 concentrations during the four years of exposure

Institute of Scientific and Technical Information of China (English)

ZHOU Yu-mei; HAN Shi-jie; LIU Ying; JIA Xia

2005-01-01

Four-year-old Pinus sylvestriformis were exposed for four growing seasons in open top chambers to ambient CO2 concentration (approx. 350 μmol·mol-1) and high CO2 concentrations (500 and 700 μmol·mol-1) at Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences at Antu Town, Jilin Province, China (42oN, 128oE). Stomatal response to elevated CO2 concentrations was examined by stomatal conductance (gs), ratio of intercellular to ambient CO2 concentration (ci/ca) and stomatal number. Reciprocal transfer experiments of stomatal conductance showed that stomatal conductance in high-[CO2]-grown plants increased in comparison with ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration and at the same measurement CO2 concentration (except a reduction in 700 μmol·mol-1 CO2 grown plants compared with plants on unchambered field when measured at growth CO2 concentration and 350 μmol·mol-1CO2). High-[CO2]-grown plants exhibited lower ci/ca ratios than ambient-[CO2]-grown plants when measured at their respective growth CO2 concentration. However, ci/ca ratios increased for plants grown in high CO2 concentrations compared with control plants when measured at the same CO2 concentration. There was no significant difference in stomatal number per unit long needle between elevated and ambient CO2. However, elevated CO2 concentrations reduced the total stomatal number of whole needle by the decline of stomatal line and changed the allocation pattern of stomata between upper and lower surface of needle.

Range Compressed Holographic Aperture Ladar

Science.gov (United States)

2017-06-01

entropy saturation behavior of the estimator is analytically described. Simultaneous range-compression and aperture synthesis is experimentally...4 2.1 Circular and Inverse -Circular HAL...2.3 Single Aperture, Multi-λ Imaging ...................................................................................... 14 2.4 Simultaneous Range

Ethylene limits abscisic acid- or soil drying-induced stomatal closure in aged wheat leaves.

Science.gov (United States)

Chen, Lin; Dodd, Ian C; Davies, William J; Wilkinson, Sally

2013-10-01

The mechanism of age-induced decreased stomatal sensitivity to abscisic acid (ABA) and soil drying has been explored here. Older, fully expanded leaves partly lost their ability to close stomata in response to foliar ABA sprays, and soil drying which stimulated endogenous ABA production, while young fully expanded leaves closed their stomata more fully. However, ABA- or soil drying-induced stomatal closure of older leaves was partly restored by pretreating plants with 1-methylcyclopropene (1-MCP), which can antagonize ethylene receptors, or by inoculating soil around the roots with the rhizobacterium Variovorax paradoxus 5C-2, which contains 1-aminocyclopropane-1-carboxylic acid (ACC)-deaminase. ACC (the immediate biosynthetic precursor of ethylene) sprays revealed higher sensitivity of stomata to ethylene in older leaves than younger leaves, despite no differences in endogenous ACC concentrations or ethylene emission. Taken together, these results indicate that the relative insensitivity of stomatal closure to ABA and soil drying in older leaves is likely due to altered stomatal sensitivity to ethylene, rather than ethylene production. To our knowledge, this is the first study to mechanistically explain diminished stomatal responses to soil moisture deficit in older leaves, and the associated reduction in leaf water-use efficiency. © 2013 John Wiley & Sons Ltd.

The effect of competition from neighbours on stomatal conductance in lettuce and tomato plants.

Science.gov (United States)

Vysotskaya, Lidiya; Wilkinson, Sally; Davies, William J; Arkhipova, Tatyana; Kudoyarova, Guzel

2011-05-01

Competition decreased transpiration from young lettuce plants after 2 days, before any reductions in leaf area became apparent, and stomatal conductance (g(s) ) of lettuce and tomato plants was also reduced. Stomatal closure was not due to hydraulic signals or competition for nutrients, as soil water content, leaf water status and leaf nitrate concentrations were unaffected by neighbours. Competition-induced stomatal closure was absent in an abscisic acid (ABA)-deficient tomato mutant, flacca, indicating a fundamental involvement of ABA. Although tomato xylem sap ABA concentrations were unaffected by the presence of neighbours, ABA/pH-based stomatal modulation is still likely to underlie the response to competition, as soil and xylem sap alkalization was observed in competing plants. Competition also modulated leaf ethylene production, and treatment of lettuce plants with an ethylene perception inhibitor (1-methylcyclopropene) diminished the difference in g(s) between single and competing plants grown in a controlled environment room, but increased it in plants grown in the greenhouse: ethylene altered the extent of the stomatal response to competition. Effects of competition on g(s) are discussed in terms of the detection of the absence of neighbours: increases in g(s) and carbon fixation may allow faster initial space occupancy within an emerging community/crop. © 2011 Blackwell Publishing Ltd.

Synthetic Aperture Sequential Beamforming

DEFF Research Database (Denmark)

Kortbek, Jacob; Jensen, Jørgen Arendt; Gammelmark, Kim Løkke

2008-01-01

A synthetic aperture focusing (SAF) technique denoted Synthetic Aperture Sequential Beamforming (SASB) suitable for 2D and 3D imaging is presented. The technique differ from prior art of SAF in the sense that SAF is performed on pre-beamformed data contrary to channel data. The objective is to im......A synthetic aperture focusing (SAF) technique denoted Synthetic Aperture Sequential Beamforming (SASB) suitable for 2D and 3D imaging is presented. The technique differ from prior art of SAF in the sense that SAF is performed on pre-beamformed data contrary to channel data. The objective...... is to improve and obtain a more range independent lateral resolution compared to conventional dynamic receive focusing (DRF) without compromising frame rate. SASB is a two-stage procedure using two separate beamformers. First a set of Bmode image lines using a single focal point in both transmit and receive...... is stored. The second stage applies the focused image lines from the first stage as input data. The SASB method has been investigated using simulations in Field II and by off-line processing of data acquired with a commercial scanner. The performance of SASB with a static image object is compared with DRF...

Loss of nitrate reductases NIA1 and NIA2 impairs stomatal closure by altering genes of core ABA signaling components in Arabidopsis.

Science.gov (United States)

Zhao, Chenchen; Cai, Shengguan; Wang, Yizhou; Chen, Zhong-Hua

2016-06-02

Nitrate reductases NIA1 and NIA2 determine NO production in plants and are critical to abscisic acid (ABA)-induced stomatal closure. However, the role for NIA1 and NIA2 in ABA signaling has not been paid much attention in nitrate reductase loss-of-function mutant nia1nia2. Recently, we have demonstrated that ABA-inhibited K(+)in current and ABA-enhanced slow anion current were absent in nia1nia2. Exogenous NO restored regulation of these channels for stomatal closure in nia1nia2. In this study, we found that mutating NIA1 and NIA2 impaired nearly all the key components of guard cell ABA signaling pathway in Arabidopsis. We also propose a simplified model for ABA signaling in the nia1nia2 mutant.

Stomatal design principles in synthetic and real leaves

DEFF Research Database (Denmark)

Zwieniecki, Maciej A.; Haaning, Katrine S; Boyce, C. Kevin

2016-01-01

Stomata are portals in plant leaves that control gas exchange for photosynthesis, a process fundamental to life on Earth. Gas fluxes and plant productivity depend on external factors such as light, water and CO2 availability and on the geometrical properties of the stoma pores. The link between...... for major trends in stomatal patterning are not well understood. Here, we use a combination of biomimetic experiments and theory to rationalize the observed changes in stoma geometry. We show that the observed correlations between stoma size and density are consistent with the hypothesis that plants favour...... efficient use of space and maximum control of dynamic gas conductivity, and that the capacity for gas exchange in plants has remained constant over at least the last 325 Myr. Our analysis provides a new measure to gauge the relative performance of species based on their stomatal characteristics....

Seasonal ozone uptake by a warm-temperate mixed deciduous and evergreen broadleaf forest in western Japan estimated by the Penman–Monteith approach combined with a photosynthesis-dependent stomatal model

International Nuclear Information System (INIS)

Kitao, Mitsutoshi; Komatsu, Masabumi; Hoshika, Yasutomo; Yazaki, Kenichi; Yoshimura, Kenichi; Fujii, Saori; Miyama, Takafumi; Kominami, Yuji

2014-01-01

Canopy-level stomatal conductance over a warm-temperate mixed deciduous and evergreen broadleaf forest in Japan was estimated by the Penman–Monteith approach, as compensated by a semi-empirical photosynthesis-dependent stomatal model, where photosynthesis, relative humidity, and CO 2 concentration were assumed to regulate stomatal conductance. This approach, using eddy covariance data and routine meteorological observations at a flux tower site, permits the continuous estimation of canopy-level O 3 uptake, even when the Penman–Monteith approach is unavailable (i.e. in case of direct evaporation from soil or wet leaves). Distortion was observed between the AOT40 exposure index and O 3 uptake through stomata, as AOT40 peaked in April, but with O 3 uptake occurring in July. Thus, leaf pre-maturation in the predominant deciduous broadleaf tree species (Quercus serrata) might suppress O 3 uptake in springtime, even when the highest O 3 concentrations were observed. -- Highlights: • We estimate canopy-level O 3 uptake in a warm-temperate mixed forest in Japan. • The Penman–Monteith approach is compensated by a photosynthesis-dependent model. • Stomatal conductance can be estimated, even in a partly-opened or wet canopy. • The estimated O 3 dose peaks in summer though O 3 exposure peaks in spring. -- Estimation of seasonal O 3 uptake over a mixed-temperate forest compensated by a photosynthesis-dependent stomatal model

Filled aperture concepts for the Terrestrial Planet Finder

Science.gov (United States)

Ridgway, Stephen T.

2003-02-01

Filled aperture telescopes can deliver a real, high Strehl image which is well suited for discrimination of faint planets in the vicinity of bright stars and against an extended exo-zodiacal light. A filled aperture offers a rich variety of PSF control and diffraction suppression techniques. Filled apertures are under consideration for a wide spectral range, including visible and thermal-IR, each of which offers a significant selection of biomarker molecular bands. A filled aperture visible TPF may be simpler in several respects than a thermal-IR nuller. The required aperture size (or baseline) is much smaller, and no cryogenic systems are required. A filled aperture TPF would look and act like a normal telescope - vendors and users alike would be comfortable with its design and operation. Filled aperture telescopes pose significant challenges in production of large primary mirrors, and in very stringent wavefront requirements. Stability of the wavefront control, and hence of the PSF, is a major issue for filled aperture systems. Several groups have concluded that these and other issues can be resolved, and that filled aperture options are competitive for a TPF precursor and/or for the full TPF mission. Ball, Boeing-SVS and TRW have recently returned architecture reviews on filled aperture TPF concepts. In this paper, I will review some of the major considerations underlying these filled aperture concepts, and suggest key issues in a TPF Buyers Guide.

Ulcerative Uremic Stomatitis - Review of the Literature and A Rare Case Report

Directory of Open Access Journals (Sweden)

Shantala Arunkumar

2015-01-01

Full Text Available Uremic Stomatitis (US represents a comparatively uncommon intraoral complication seen, mostly, in cases of end-stage renal disease or undiagnosed or untreated chronic renal failure. Its frequency has diminished due to the advent of renal dialysis. Clinically uremic stomatitis is characterized by the presence of painful plaques and crusts that are usually distributed on the buccal and labial mucosa, dorsal or ventral surface of the tongue, gingiva, and floor of the mouth. Ultimate treatment consists of improvement of blood urea concentration and underlying renal failure is supported by enhancement of oral hygiene with antiseptic mouthwashes and antimicrobial/antifungal agents, if necessary. Here we report a rare case of ulcerative type of uremic stomatitis occurring in a patient of chronic renal failure due to sudden relapse of uremia and reviewed the possible pathophysiology of oral symptoms of chronic renal failure.

Ozone exposure and stomatal sluggishness in different plant physiognomic classes

Energy Technology Data Exchange (ETDEWEB)

Paoletti, Elena, E-mail: e.paoletti@ipp.cnr.i [IPP-CNR, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Florence (Italy); Grulke, Nancy E. [US Forest Service, 4955 Canyon Crest Drive, Riverside, CA 92507 (United States)

2010-08-15

Gas exchange responses to static and variable light were tested in three species: snap bean (Phaseolus vulgaris, two cultivars), California black oak (Quercus kelloggii), and blue oak (Q. douglasii). The effects of 1-month (snap beans) and 2-month (oaks) O{sub 3} (ozone) exposure (70 ppb over 8 h per day in open-top chambers) were investigated. A delay in stomatal responses (i.e., 'sluggish' responses) to variable light was found to be both an effect of O{sub 3} exposure and a reason for increased O{sub 3} sensitivity in snap bean cultivars, as it implied higher O{sub 3} uptake during times of disequilibrium. Sluggishness increased the time to open (thus limiting CO{sub 2} uptake) and close stomata (thus increasing transpirational water loss) after abrupt changes in light level. Similar responses were shown by snap beans and oaks, suggesting that O{sub 3}-induced stomatal sluggishness is a common trait among different plant physiognomic classes. - Sluggish stomatal responses are suggested to be both an effect of O{sub 3} exposure and a reason of increased O{sub 3} sensitivity in plants.

Measurements of pore-scale flow through apertures

Energy Technology Data Exchange (ETDEWEB)

Chojnicki, Kirsten [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-09-01

Pore-scale aperture effects on flow in pore networks was studied in the laboratory to provide a parameterization for use in transport models. Four cases were considered: regular and irregular pillar/pore alignment with and without an aperture. The velocity field of each case was measured and simulated, providing quantitatively comparable results. Two aperture effect parameterizations were considered: permeability and transmission. Permeability values varied by an order of magnitude between the cases with and without apertures. However, transmission did not correlate with permeability. Despite having much greater permeability the regular aperture case permitted less transmission than the regular case. Moreover, both irregular cases had greater transmission than the regular cases, a difference not supported by the permeabilities. Overall, these findings suggest that pore-scale aperture effects on flow though a pore-network may not be adequately captured by properties such as permeability for applications that are interested in determining particle transport volume and timing.

Manipulation of the apoplastic pH of intact plants mimics stomatal and growth responses to water availability and microclimatic variation.

Science.gov (United States)

Wilkinson, Sally; Davies, William J

2008-01-01

The apoplastic pH of intact Forsythiaxintermedia (cv. Lynwood) and tomato (Solanum lycopersicum) plants has been manipulated using buffered foliar sprays, and thereby stomatal conductance (g(s)), leaf growth rate, and plant water loss have been controlled. The more alkaline the pH of the foliar spray, the lower the g(s) and/or leaf growth rate subsequently measured. The most alkaline pH that was applied corresponds to that measured in sap extracted from shoots of tomato and Forsythia plants experiencing, respectively, soil drying or a relatively high photon flux density (PFD), vapour pressure deficit (VPD), and temperature in the leaf microclimate. The negative correlation between PFD/VPD/temperature and g(s) determined in well-watered Forsythia plants exposed to a naturally varying summer microclimate was eliminated by spraying the plants with relatively alkaline but not acidic buffers, providing evidence for a novel pH-based signalling mechanism linking the aerial microclimate with stomatal aperture. Increasing the pH of the foliar spray only reduced g(s) in plants of the abscisic acid (ABA)-deficient flacca mutant of tomato when ABA was simultaneously sprayed onto leaves or injected into stems. In well-watered Forsythia plants exposed to a naturally varying summer microclimate (variable PFD, VPD, and temperature), xylem pH and leaf ABA concentration fluctuated but were positively correlated. Manipulation of foliar apoplastic pH also affected the response of g(s) and leaf growth to ABA injected into stems of intact Forsythia plants. The techniques used here to control physiology and water use in intact growing plants could easily be applied in a horticultural context.

Daya Hambat Infusum Daun Sirih Terhadap Pertumbuhan Staphylococcus aureus Yang Diisolasi Dari Denture Stomatitis ; Penelitian In Vitro.

OpenAIRE

bin Abdullah, Muhammad Naim

2011-01-01

Denture Stomatitis merupakan lesi mukosa oral berwarna merah, sakit, dan bengkak, kondisi ini karena kebiasaan jelek pada pemakai gigitiruan yang tidak mumbuka protesa pada malam hari dan jarang dibersihkan. Faktor sistemik yang mendukung terjadinya Denture Stomatitis dapat disebabkan oleh beberapa bakteri, salah satunya Staphylococcus aureus. Pencegahan Denture Stomatitis dapat dilakukan dengan sering membersihkan gigitiruan dan pemakaian obat kumur. Tujuan penelitian ini adalah untuk menguj...

A genetic screen reveals Arabidopsis stomatal and/or apoplastic defenses against Pseudomonas syringae pv. tomato DC3000.

Directory of Open Access Journals (Sweden)

Weiqing Zeng

2011-10-01

Full Text Available Bacterial infection of plants often begins with colonization of the plant surface, followed by entry into the plant through wounds and natural openings (such as stomata, multiplication in the intercellular space (apoplast of the infected tissues, and dissemination of bacteria to other plants. Historically, most studies assess bacterial infection based on final outcomes of disease and/or pathogen growth using whole infected tissues; few studies have genetically distinguished the contribution of different host cell types in response to an infection. The phytotoxin coronatine (COR is produced by several pathovars of Pseudomonas syringae. COR-deficient mutants of P. s. tomato (Pst DC3000 are severely compromised in virulence, especially when inoculated onto the plant surface. We report here a genetic screen to identify Arabidopsis mutants that could rescue the virulence of COR-deficient mutant bacteria. Among the susceptible to coronatine-deficient Pst DC3000 (scord mutants were two that were defective in stomatal closure response, two that were defective in apoplast defense, and four that were defective in both stomatal and apoplast defense. Isolation of these three classes of mutants suggests that stomatal and apoplastic defenses are integrated in plants, but are genetically separable, and that COR is important for Pst DC3000 to overcome both stomatal guard cell- and apoplastic mesophyll cell-based defenses. Of the six mutants defective in bacterium-triggered stomatal closure, three are defective in salicylic acid (SA-induced stomatal closure, but exhibit normal stomatal closure in response to abscisic acid (ABA, and scord7 is compromised in both SA- and ABA-induced stomatal closure. We have cloned SCORD3, which is required for salicylic acid (SA biosynthesis, and SCORD5, which encodes an ATP-binding cassette (ABC protein, AtGCN20/AtABCF3, predicted to be involved in stress-associated protein translation control. Identification of SCORD5 begins to

Evidence-based modelling of diverse plant water use strategies on stomatal and non-stomatal components under drought

Science.gov (United States)

zhou, S.; Prentice, C.; Medlyn, B. E.; Sabaté, S.

2013-12-01

Models disagree on how to represent effects of drought stress on plant gas exchange. Some models assume drought stress affects the marginal water use efficiency of plants (marginal WUE; i.e. the change in photosynthesis per unit of change in transpiration) whereas others assume drought stress acts directly on photosynthetic capacity. It is not clear whether either of these approaches is sufficient to capture the drought response, or whether the effect of drought varies among species and functional types. A collection of Eucalyptus and Quercus species derived from different hydro-climate habitats, in together with two European riparian species, were conducted with drought treatments respectively in Australia and Spain for three months. Measurements included net CO2 assimilation rate versus substomatal CO2 concentration (A-Ci) curves, fluorescence, and predawn leaf water potential at increasing levels of water stress. The correlations with quantitative plant traits of leaf, stomata, vessel, and wood density, leaf nitrogen content and 13C discrimination were also explored. We analysed the effect of drought effect on leaf gas exchange with a recently developed stomatal model that reconciles the empirical and optimal approaches on predicting optimal stomatal conductance. The model's single parameter g1 is a decreasing function of marginal WUE. The two genera showed consistence on the contrasting response patterns between species derived from mesic and arid habitats, which differed greatly in their estimated g1 values under moist conditions, and in the rate at which g1 declined with water stress. They also differed greatly in the predawn water potential at which apparent carboxylation capacity (apparent Vcmax) and mesophyll conductance (gm) declined most steeply, and in the steepness of this decline. Principal components analysis revealed a gradient in water relation strategies from sclerophyll species to malacophyll species. Malacophylls had higher g1, apparent Vcmax

Observations of leaf stomatal conductance at the canopy scale: an atmospheric modeling perspective

International Nuclear Information System (INIS)

Avissar, R.

1993-01-01

Plant stomata play a key role in the redistribution of energy received on vegetated land into sensible and latent heat. As a result, they have a considerable impact on the atmospheric planetary boundary layer, the hydrologic cycle, the climate, and the weather. Current parameterizations of the stomatal mechanism in state-of-the-art atmospheric models are based on empirical relations that are established at the leaf scale between stomatal conductance and environmental conditions. In order to evaluate these parameterizations, an experiment was carried out on a potato field in New Jersey during the summer of 1989. Stomatal conductances were measured within a small homogeneous area in the middle of the potato field and under a relatively broad range of atmospheric conditions. A large variability of stomatal conductances was observed. This variability, which was associated with the variability of micro-environmental and physiological conditions that is found even in a homogeneous canopy, cannot be simulated explicitly on the scale of a single agricultural field and,a fortiori, on the scale of atmospheric models. Furthermore, this variability could not be related to the environmental conditions measured at a height of 2 m above the plant canopy simultaneously with the conductances, reinforcing the concept of scale decoupling suggested by Jarvis and McNaughton (1986) and McNaughton and Jarvis (1991). Thus, for atmospheric modeling purposes, a parameterization of stomatal conductance at the canopy scale using external environmental forcing conditions seems more appropriate than a parameterization based on leaf-scale stomatal conductance, as currently adopted in state-of-the-art atmospheric models. The measured variability was characterized by a lognormal probability density function (pdf) that remained relatively stable during the entire measuring period. These observations support conclusions by McNaughton and Jarvis (1991) that, unlike current parameterizations, a

Observations of leaf stomatal conductance at the canopy scale: an atmospheric modeling perspective

International Nuclear Information System (INIS)

Avissar, R.

1993-01-01

Plant stomata play a key role in the redistribution of energy received on vegetated land into sensible and latent heat. As a result, they have a considerable impact on the atmospheric planetary boundary layer, the hydrologic cycle, the climate, and the weather. Current parameterizations of the stomatal mechanism in state-of-the-art atmospheric models are based on empirical relations that are established at the leaf scale between stomatal conductance and environmental conditions. In order to evaluate these parameterizations, an experiment was carried out on a potato field in New Jersey during the summer of 1989. Stomatal conductances were measured within a small homogeneous area in the middle of the potato field and under a relatively broad range of atmospheric conditions. A large variability of stomatal conductances was observed. This variability, which was associated with the variability of micro-environmental and physiological conditions that is found even in a homogeneous canopy, cannot be simulated explicitly on the scale of a single agricultural field and, a fortiori, on the scale of atmospheric models. Furthermore, this variability could not be related to the environmental conditions measured at a height of 2 m above the plant canopy simultaneously with the conductances, reinforcing the concept of scale decoupling suggested by Jarvis and McNaughton (1986) and McNaughton and Jarvis (1991). Thus, for atmospheric modeling purposes, a parameterization of stomatal conductance at the canopy scale using external environmental forcing conditions seems more appropriate than a parameterization based on leaf-scale stomatal conductance, as currently adopted in state-of-the-art atmospheric models. The measured variability was characterized by a lognormal probability density function (pdf) that remained relatively stable during the entire measuring period. These observations support conclusions by McNaughton and Jarvis (1991) that, unlike current parameterizations, a

Calibration of the TUD Ku-band Synthetic Aperture Radiometer

DEFF Research Database (Denmark)

Laursen, Brian; Skou, Niels

1995-01-01

The TUD Synthetic Aperture Radiometer is a 2-channel demonstration model that can simulate a thinned aperture radiometer having an unfilled aperture consisting of several small antenna elements. Aperture synthesis obtained by interferometric measurements using the antenna elements in pairs, follo...

Simultaneous requirement of carbon dioxide and abscisic acid for stomatal closing in Xanthium strumarium L.

Science.gov (United States)

Raschke, K

1975-01-01

Open stomata of detached leaves of Xanthium strumarium L. closed only when carbon dioxide and abscisic acid (ABA) were presented simultaneously. Three parameters of stomatal closing were determined after additions of ABA to the irrigation water of detached leaves, while the leaves were exposed to various CO2 concentrations ([CO2]s) in the air; a) the delay between addition of ABA and a reduction of stomatal conductance by 5%, b) the velocity of stomatal closing, and c) the new conductance. Changes in all three parameters showed that stomatal responses to ABA were enhanced by CO2; this effect followed saturation kinetics. Half saturation occurred at an estimated [CO2] in the stomatal pore of 200 μl l(-1). With respect to ABA, stomata responded in normal air with half their maximal amplitude at [ABA]s between 10(-6) and 10(-5) M(+-)-ABA. The amounts of ABA taken up by the leaves during the delay increased with a power strumarium.Based on earlier findings and on the results of this investigation it is suggested that stomata close if the cytoplasm of the guard cells contains much malate and H(+). The acid content in turn is determined by the relative rates of production of malic acid (from endogenous as well as exogenous CO2) and its removal (by transport of the anion into the vacuole and exchange of the H(+) for K(+) with the environment of the guard cells). The simultaneous requirement of CO2 and ABA for stomatal closure leads to the inference that ABA inhibits the expulsion of H(+) from guard cells.

Is optimality in stomatal conductance an endogenous process or an emergent property arising from interactions with the environment?

Science.gov (United States)

Resco de Dios, Victor; Gessler, Arthur; Ferrio, Juan Pedro; Bahn, Michael; Milcu, Alexandru; Tissue, David; Voltas, Jordi; Roy, Jacques

2016-04-01

Plants are sessile and poikilothermic organisms that need to respond and adjust promptly to an ever-changing environment. Over a single 24 h period, a plant may experience the same level of variation in radiation as in its entire life-time and, in some climates, the oscillation in day-night temperature and vapor pressure deficit might be of similar magnitude to that experienced across a full year. Plants need to maintain a positive C balance without depleting soil water reserves in the face of such a diverse environment, and feedbacks between assimilation (A) and water losses (E) are thought to have evolved to optimize stomatal conductance (gs). In short, the optimal conductance hypothesis proposes that cross-talks between A and stomatal conductance gs lead to a constant marginal water use (λ) during a day, such that A is maximized and E minimized. The biological mechanism by which biochemical processes would feedback gs remains unknown, but multiple studies have shown empirical support for this hypothesis, leading to its current consideration of theory by many. Here we test whether optimal stomatal conductance is an endogenous property, that is, driven solely by factors internal to the plant, and in the absence of environmental fluctuations. After 5 days of entrainment, where monoculture canopies of bean and of cotton were subjected to the average environmental conditions of an August sunny day in Montpellier (at the CNRS European Ecotron, FR), we kept temperature, relative humidity and photosynthetically active radiation constant for 48 h at the values observed at noon. During this period, we monitored leaf gas exchange continuously every two minutes, and canopy gas exchange every 15 minutes. We observed a periodic oscillation in λ, showing a 24 h period, and consistent with a circadian regulation of water use efficiency. Hourly variations in λ could thus not be explained by the optimal stomatal hypothesis. Moreover, the pattern of variation (of maximal water

Oral symptoms and salivary findings in oral lichen planus, oral lichenoid lesions and stomatitis

DEFF Research Database (Denmark)

Larsen, Kristine Roen; Johansen, Jeanne Duus; Reibel, Jesper

2017-01-01

BACKGROUND: To examine if patients with oral lichen planus, oral lichenoid lesions and generalised stomatitis and concomitant contact allergy have more frequent and severe xerostomia, lower unstimulated and chewing-stimulated saliva and citric-acid-stimulated parotid saliva flow rates, and higher...... of xerostomia, clinical examination, sialometry, mucosal biopsy and contact allergy testing. RESULTS: Nineteen patients had oral lichen planus, 19 patients had oral lichenoid lesions and 11 patients had generalised stomatitis. 38.8% had contact allergy. Xerostomia was significantly more common and severe...... in the chewing stimulated saliva samples from patients when compared to healthy controls. The differences were not significant and they were irrespective of the presence of contact allergy. CONCLUSION: Xerostomia is prevalent in patients with oral lichen planus, lichenoid lesions and generalised stomatitis...

Evaluation of Multiple Mechanistic Hypotheses of Leaf Photosynthesis and Stomatal Conductance against Diurnal and Seasonal Data from Two Contrasting Panamanian Tropical Forests

Science.gov (United States)

Serbin, S.; Walker, A. P.; Wu, J.; Ely, K.; Rogers, A.; Wolfe, B.

2017-12-01

Tropical forests play a key role in regulating the global carbon (C), water, and energy cycles and stores, as well as influence climate through the exchanges of mass and energy with the atmosphere. However, projected changes in temperature and precipitation patterns are expected to impact the tropics and the strength of the tropical C sink, likely resulting in significant climate feedbacks. Moreover, the impact of stronger, longer, and more extensive droughts not well understood. Critical for the accurate modeling of the tropical C and water cycle in Earth System Models (ESMs) is the representation of the coupled photosynthetic and stomatal conductance processes and how these processes are impacted by environmental and other drivers. Moreover, the parameterization and representation of these processes is an important consideration for ESM projections. We use a novel model framework, the Multi-Assumption Architecture and Testbed (MAAT), together with the open-source bioinformatics toolbox, the Predictive Ecosystem Analyzer (PEcAn), to explore the impact of the multiple mechanistic hypotheses of coupled photosynthesis and stomatal conductance as well as the additional uncertainty related to model parameterization. Our goal was to better understand how model choice and parameterization influences diurnal and seasonal modeling of leaf-level photosynthesis and stomatal conductance. We focused on the 2016 ENSO period and starting in February, monthly measurements of diurnal photosynthesis and conductance were made on 7-9 dominant species at the two Smithsonian canopy crane sites. This benchmark dataset was used to test different representations of stomatal conductance and photosynthetic parameterizations with the MAAT model, running within PEcAn. The MAAT model allows for the easy selection of competing hypotheses to test different photosynthetic modeling approaches while PEcAn provides the ability to explore the uncertainties introduced through parameterization. We

Beam aperture modifier design with acoustic metasurfaces

Science.gov (United States)

Tang, Weipeng; Ren, Chunyu

2017-10-01

In this paper, we present a design concept of acoustic beam aperture modifier using two metasurface-based planar lenses. By appropriately designing the phase gradient profile along the metasurface, we obtain a class of acoustic convex lenses and concave lenses, which can focus the incoming plane waves and collimate the converging waves, respectively. On the basis of the high converging and diverging capability of these lenses, two kinds of lens combination scheme, including the convex-concave type and convex-convex type, are proposed to tune up the incoming beam aperture as needed. To be specific, the aperture of the acoustic beam can be shrunk or expanded through adjusting the phase gradient of the pair of lenses and the spacing between them. These lenses and the corresponding aperture modifiers are constructed by the stacking ultrathin labyrinthine structures, which are obtained by the geometry optimization procedure and exhibit high transmission coefficient and a full range of phase shift. The simulation results demonstrate the effectiveness of our proposed beam aperture modifiers. Due to the flexibility in aperture controlling and the simplicity in fabrication, the proposed modifiers have promising potential in applications, such as acoustic imaging, nondestructive evaluation, and communication.

A system dynamics model integrating physiology and biochemical regulation predicts extent of crassulacean acid metabolism (CAM) phases.

Science.gov (United States)

Owen, Nick A; Griffiths, Howard

2013-12-01

A system dynamics (SD) approach was taken to model crassulacean acid metabolism (CAM) expression from measured biochemical and physiological constants. SD emphasizes state-dependent feedback interaction to describe the emergent properties of a complex system. These mechanisms maintain biological systems with homeostatic limits on a temporal basis. Previous empirical studies on CAM have correlated biological constants (e.g. enzyme kinetic parameters) with expression over the CAM diel cycle. The SD model integrates these constants within the architecture of the CAM 'system'. This allowed quantitative causal connections to be established between biological inputs and the four distinct phases of CAM delineated by gas exchange and malic acid accumulation traits. Regulation at flow junctions (e.g. stomatal and mesophyll conductance, and malic acid transport across the tonoplast) that are subject to feedback control (e.g. stomatal aperture, malic acid inhibition of phosphoenolpyruvate carboxylase, and enzyme kinetics) was simulated. Simulated expression for the leaf-succulent Kalanchoë daigremontiana and more succulent tissues of Agave tequilana showed strong correlation with measured gas exchange and malic acid accumulation (R(2)  = 0.912 and 0.937, respectively, for K. daigremontiana and R(2)  = 0.928 and 0.942, respectively, for A. tequilana). Sensitivity analyses were conducted to quantitatively identify determinants of diel CO2 uptake. The transition in CAM expression from low to high volume/area tissues (elimination of phase II-IV carbon-uptake signatures) was achieved largely by the manipulation three input parameters. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Ion mobility spectrometer with virtual aperture grid

Science.gov (United States)

Pfeifer, Kent B.; Rumpf, Arthur N.

2010-11-23

An ion mobility spectrometer does not require a physical aperture grid to prevent premature ion detector response. The last electrodes adjacent to the ion collector (typically the last four or five) have an electrode pitch that is less than the width of the ion swarm and each of the adjacent electrodes is connected to a source of free charge, thereby providing a virtual aperture grid at the end of the drift region that shields the ion collector from the mirror current of the approaching ion swarm. The virtual aperture grid is less complex in assembly and function and is less sensitive to vibrations than the physical aperture grid.

Aquaporins Contribute to ABA-Triggered Stomatal Closure through OST1-Mediated Phosphorylation

Science.gov (United States)

Grondin, Alexandre; Rodrigues, Olivier; Verdoucq, Lionel; Merlot, Sylvain; Leonhardt, Nathalie; Maurel, Christophe

2015-01-01

Stomatal movements in response to environmental stimuli critically control the plant water status. Although these movements are governed by osmotically driven changes in guard cell volume, the role of membrane water channels (aquaporins) has remained hypothetical. Assays in epidermal peels showed that knockout Arabidopsis thaliana plants lacking the Plasma membrane Intrinsic Protein 2;1 (PIP2;1) aquaporin have a defect in stomatal closure, specifically in response to abscisic acid (ABA). ABA induced a 2-fold increase in osmotic water permeability (Pf) of guard cell protoplasts and an accumulation of reactive oxygen species in guard cells, which were both abrogated in pip2;1 plants. Open stomata 1 (OST1)/Snf1-related protein kinase 2.6 (SnRK2.6), a protein kinase involved in guard cell ABA signaling, was able to phosphorylate a cytosolic PIP2;1 peptide at Ser-121. OST1 enhanced PIP2;1 water transport activity when coexpressed in Xenopus laevis oocytes. Upon expression in pip2;1 plants, a phosphomimetic form (Ser121Asp) but not a phosphodeficient form (Ser121Ala) of PIP2;1 constitutively enhanced the Pf of guard cell protoplasts while suppressing its ABA-dependent activation and was able to restore ABA-dependent stomatal closure in pip2;1. This work supports a model whereby ABA-triggered stomatal closure requires an increase in guard cell permeability to water and possibly hydrogen peroxide, through OST1-dependent phosphorylation of PIP2;1 at Ser-121. PMID:26163575

Environmental controls on saltcedar (Tamarix spp.) transpiration and stomatal conductance and implications for determining evapotranspiration by remote sensing

Science.gov (United States)

Nagler, P. L.; Glenn, E. P.; morino, K.

2012-12-01

Saltcedar is an introduced, salt-tolerant shrub that now dominates many flow-regulated western U.S. rivers. Saltcedar control programs have been implemented to salvage water and to allow the return of native vegetation to infested rivers. However, there is much debate about how much water saltcedar actually uses and the range of ecohydrological niches it occupies. Ground methods for measuring riparian zone ET have improved and there is considerable interest in developing remote sensing methods for saltcedar to conduct wide-area monitoring of water use. Both thermal band and vegetation index methods have been used to estimate riparian ET. However, several problems present themselves in applying existing remote sensing methods to riparian corridors. First, many riparian corridors are narrow and are surrounded by arid uplands, hence they cannot be treated as energetically closed systems, an assumption of thermal band methods that calculate ET as a residual in the surface energy balance. Second, contrary to the assumption that riparian phreatophytes typically grow under unstressed conditions since they are rooted into groundwater, we find that saltcedar stands are under substantial degrees of apparent moisture stress, exhibiting midday depression of transpiration and stomatal conductance, and decreases in stomatal conductance over the growing season as depth to groundwater increases. Furthermore, the degree of stress is site-specific, depending on local soil texture, salinity of the groundwater and distance from the river. This violates a key assumption of vegetation index methods for estimating ET. The implications of these findings for arid-zone riparian ecohydrology and for remote sensing methods that assume either a constant daily evaporative fraction or rate of stomatal conductance will be discussed using saltcedar stands measured in the Cibola NWR on the lower Colorado River as a case study. Daily rates of saltcedar transpiration ranged from 1.6-3.0 mm/m2 leaf

Infection of guinea pigs with vesicular stomatitis New Jersey virus Transmitted by Culicoides sonorensis (Diptera: Ceratopogonidae).

Science.gov (United States)

Pérez De León, Adalberto A; O'Toole, Donal; Tabachnick, Walter J

2006-05-01

Intrathoracically inoculated Culicoides sonorensis Wirth & Jones were capable of transmitting vesicular stomatitis New Jersey virus (family Rhabdoviridae, genus Vesiculovirus, VSNJV) during blood feeding on the abdomen of six guinea pigs. None of the guinea pigs infected in this manner developed clinical signs of vesicular stomatitis despite seroconversion for VSNJV. Guinea pigs infected by intradermal inoculations of VSNJV in the abdomen also failed to develop clinical signs of vesicular stomatitis. Three guinea pigs given intradermal inoculations of VSNJV in the foot pad developed lesions typical of vesicular stomatitis. Transmission by the bite of C. sonorensis may have facilitated guinea pig infection with VSNJV because a single infected C. sonorensis caused seroconversion and all guinea pigs infected by insect bite seroconverted compared with 50% of the guinea pigs infected by intradermal inoculation with a higher titer VSNJV inoculum. The role of C. sonorensis in the transmission of VSNJV is discussed.

Imaging with rotating slit apertures and rotating collimators

International Nuclear Information System (INIS)

Gindi, G.R.; Arendt, J.; Barrett, H.H.; Chiu, M.Y.; Ervin, A.; Giles, C.L.; Kujoory, M.A.; Miller, E.L.; Simpson, R.G.

1982-01-01

The statistical quality of conventional nuclear medical imagery is limited by the small signal collect through low-efficiency conventional apertures. Coded-aperture imaging overcomes this by employing a two-step process in which the object is first efficiently detected as an ''encoded'' form which does not resemble the object, and then filtered (or ''decoded'') to form an image. We present here the imaging properties of a class of time-modulated coded apertures which, unlike most coded apertures, encode projections of the object rather than the object itself. These coded apertures can reconstruct a volume object nontomographically, tomographically (one plane focused), or three-dimensionally. We describe a new decoding algorithm that reconstructs the object from its planar projections. Results of noise calculations are given, and the noise performance of these coded-aperture systems is compared to that of conventional counterparts. A hybrid slit-pinhole system which combines the imaging advantages of a rotating slit and a pinhole is described. A new scintillation detector which accurately measures the position of an event in one dimension only is presented, and its use in our coded-aperture system is outlined. Finally, results of imaging test objects and animals are given

Imaging with rotating slit apertures and rotating collimators

International Nuclear Information System (INIS)

Gindi, G.R.; Arendt, J.; Barrett, H.H.; Chiu, M.Y.; Ervin, A.; Giles, C.L.; Kujoory, M.A.; Miller, E.L.; Simpson, R.G.

1982-01-01

The statistical quality of conventional nuclear medical imagery is limited by the small signal collected through low-efficiency conventional apertures. Coded-aperture imaging overcomes this by employing a two-step process in which the object is first efficiently detected as an encoded form which does not resemble the object, and then filtered (or decoded) to form an image. We present here the imaging properties of a class of time-modulated coded apertures which, unlike most coded apertures, encode projections of the object rather than the object itself. These coded apertures can reconstruct a volume object nontomographically, tomographically (one plane focused), or three-dimensionally. We describe a new decoding algorithm that reconstructs the object from its planar projections. Results of noise calculations are given, and the noise performance of these coded-aperture systems is compared to that of conventional counterparts. A hybrid slit-pinhole system which combines the imaging advantages of a rotating slit and a pinhole is described. A new scintillation detector which accurately measures the position of an event in one dimension only is presented, and its use in our coded-aperture system is outlined. Finally, results of imaging test objects and animals are given

Serum cytokine profile and clinicopathological findings in oral lichen planus, oral lichenoid lesions and stomatitis

DEFF Research Database (Denmark)

Larsen, Kristine Røn; Johansen, Jeanne Duus; Reibel, Jesper

2017-01-01

The objective of this study was to examine if clinical and histopathological variables in patients with oral lichen planus (OLP), oral lichenoid lesions (OLL), and generalized stomatitis display different cytokine profiles and if concomitant contact allergy influences this profile. Forty-nine pat......The objective of this study was to examine if clinical and histopathological variables in patients with oral lichen planus (OLP), oral lichenoid lesions (OLL), and generalized stomatitis display different cytokine profiles and if concomitant contact allergy influences this profile. Forty...... analyzed and compared between groups. Nineteen patients had OLP, primarily with ulcerative lesions on the buccal mucosa, 19 patients had OLL, and 11 patients had generalized stomatitis. All patients had oral symptoms, mainly stinging and burning. Nineteen patients and 10 healthy subjects had contact...... higher levels of IL-6 than the healthy subjects. Interferon-γ, IL-12p40, and IL-12p70 were below detection limit. Our findings indicate that OLP, OLL, and generalized stomatitis cannot be discriminated by means of the selected serum cytokines, and that the presence of concomitant contact allergy does...

Evaluation of the stomatal conductance formulation in the EMEP ozone deposition model for Picea abies

Science.gov (United States)

Wieser, G.; Emberson, L. D.

It is widely acknowledged that the possible impacts of ozone on forest trees are more closely related to ozone flux through the stomata than to external ozone exposure. However, the application of the flux approach on a European scale requires the availability of appropriate models, such as the European Monitoring and Evaluation Programme (EMEP) ozone deposition model, for estimating ozone flux and cumulative ozone uptake. Within this model stomatal conductance is the key variable, since it determines the amount of ozone absorbed by the leaves. This paper describes the suitability of the existing EMEP ozone deposition model parameterisation and formulation to represent stomatal behaviour determined from field measurements on adult Norway spruce ( Picea abies (L.) Karst.) trees in the Central European Alps. Parameters affecting maximum stomatal conductance (e.g. seasonal phenology, needle position, needle age, nutrient deficiency and ozone itself) and stomatal response functions to temperature, irradiance, vapour pressure deficit, and soil water content are investigated. Finally, current limitations and possible alterations of the EMEP model will be discussed with respect to spatial scales of available input data for future flux modelling.

Evapotranspiration partitioning, stomatal conductance, and components of the water balance: A special case of a desert ecosystem in China

Science.gov (United States)

Zhao, Wenzhi; Liu, Bing; Chang, Xuexiang; Yang, Qiyue; Yang, Yuting; Liu, Zhiling; Cleverly, James; Eamus, Derek

2016-07-01

Partitioning evapotranspiration (ET) into its components reveals details of the processes that underlie ecosystem hydrologic budgets and their feedback to the water cycle. We measured rates of actual evapotranspiration (ETa), canopy transpiration (Tc), soil evaporation (Eg), canopy-intercepted precipitation (EI), and patterns of stomatal conductance of the desert shrub Calligonum mongolicum in northern China to determine the water balance of this ecosystem. The ETa was 251 ± 8 mm during the growing period, while EI, Tc, and Eg accounted for 3.2%, 63.9%, and 31.3%, respectively, of total water use (256 ± 4 mm) during the growing period. In this unique ecosystem, groundwater was the main water source for plant transpiration and soil evaporation, Tc and exceeded 60% of the total annual water used by desert plants. ET was not sensitive to air temperature in this unique desert ecosystem. Partitioning ET into its components improves our understanding of the mechanisms that underlie adaptation of desert shrubs, especially the role of stomatal regulation of Tc as a determinant of ecosystem water balance.

The plant homolog to the human sodium/dicarboxylic cotransporter is the vacuolar malate carrier

OpenAIRE

Emmerlich, Vera; Linka, Nicole; Reinhold, Thomas; Hurth, Marco A.; Traub, Michaela; Martinoia, Enrico; Neuhaus, H. Ekkehard

2003-01-01

Malate plays a central role in plant metabolism. It is an intermediate in the Krebs and glyoxylate cycles, it is the store for CO2 in C4 and crassulacean acid metabolism plants, it protects plants from aluminum toxicity, it is essential for maintaining the osmotic pressure and charge balance, and it is therefore involved in regulation of stomatal aperture. To fulfil many of these roles, malate has to be accumulated within the large central vacuole. Many unsuccessful efforts have been made in ...

Microfabricated high-bandpass foucault aperture for electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Glaeser, Robert; Cambie, Rossana; Jin, Jian

2014-08-26

A variant of the Foucault (knife-edge) aperture is disclosed that is designed to provide single-sideband (SSB) contrast at low spatial frequencies but retain conventional double-sideband (DSB) contrast at high spatial frequencies in transmission electron microscopy. The aperture includes a plate with an inner open area, a support extending from the plate at an edge of the open area, a half-circle feature mounted on the support and located at the center of the aperture open area. The radius of the half-circle portion of reciprocal space that is blocked by the aperture can be varied to suit the needs of electron microscopy investigation. The aperture is fabricated from conductive material which is preferably non-oxidizing, such as gold, for example.

Impact of Canopy Coupling on Canopy Average Stomatal Conductance Across Seven Tree Species in Northern Wisconsin

Science.gov (United States)

Ewers, B. E.; Mackay, D. S.; Samanta, S.; Ahl, D. E.; Burrows, S. S.; Gower, S. T.

2001-12-01

Land use changes over the last century in northern Wisconsin have resulted in a heterogeneous landscape composed of the following four main forest types: northern hardwoods, northern conifer, aspen/fir, and forested wetland. Based on sap flux measurements, aspen/fir has twice the canopy transpiration of northern hardwoods. In addition, daily transpiration was only explained by daily average vapor pressure deficit across the cover types. The objective of this study was to determine if canopy average stomatal conductance could be used to explain the species effects on tree transpiration. Our first hypothesis is that across all of the species, stomatal conductance will respond to vapor pressure deficit so as to maintain a minimum leaf water potential to prevent catostrophic cavitiation. The consequence of this hypothesis is that among species and individuals there is a proportionality between high stomatal conductance and the sensitivity of stomatal conductance to vapor pressure deficit. Our second hypothesis is that species that do not follow the proportionality deviate because the canopies are decoupled from the atmosphere. To test our two hypotheses we calculated canopy average stomatal conductance from sap flux measurements using an inversion of the Penman-Monteith equation. We estimated the canopy coupling using a leaf energy budget model that requires leaf transpiration and canopy aerodynamic conductance. We optimized the parameters of the aerodynamic conductance model using a Monte Carlo technique across six parameters. We determined the optimal model for each species by selecting parameter sets that resulted in the proportionality of our first hypothesis. We then tested the optimal energy budget models of each species by comparing leaf temperature and leaf width predicted by the models to measurements of each tree species. In red pine, sugar maple, and trembling aspen trees under high canopy coupling conditions, we found the hypothesized proportionality

Reconstitution of the fusogenic activity of vesicular stomatitis virus

NARCIS (Netherlands)

Metsikkö, K.; van Meer, G.; Simons, K.

1986-01-01

Enveloped virus glycoproteins exhibit membrane fusion activity. We have analysed whether the G protein of vesicular stomatitis virus, reconstituted into liposomes, is able to fuse nucleated cells in a pH-dependent fashion. Proteoliposomes produced by octylglucoside dialysis did not exhibit cell

Beam focusing by aperture displacement in multiampere ion sources

International Nuclear Information System (INIS)

Stewart, L.D.; Kim, J.; Matsuda, S.

1975-05-01

Results are given of an experimental study of beam focusing by aperture displacement (Δx) in duoPIGatron ion sources. Measurements with a single aperture, accel-decel electrode geometry show that the beam deflection angle is linear with Δx/z for the round aperture and with Δx/z* 2 for the slit aperture where z and z* are respectively the extraction gap distance and the effective gap distance. Applying the result of the single aperture study to the multiaperture, duoPIGatron sources, it was possible to increase the neutral beam injection power to the ORMAK plasma by approximately 40 percent. Also presented are discussion and comparison of other work on the effect of aperture displacement on beam deflection. (U.S.)

Linking stomatal sensitivity and whole-tree hydraulic architecture

Science.gov (United States)

Katherine A. McCulloh; David R. Woodruff

2012-01-01

Despite the complexity of the relationship between stomatal sensitivity, water loss and vulnerability to embolism, the goal of teasing apart the subtleties is a necessary one. As Litvak et al. (2012) mention, determining transpiration patterns based on vulnerability to embolism would be much easier than the lengthy and potentially expensive processes involved in sap...

Stomatal development in barley as a bioassay for cell differentation: its use with X-rays and gibberellic acid

Energy Technology Data Exchange (ETDEWEB)

Zeiger, E; Rafalowsky, J [Chile Univ., Santiago. Departamento de Biologia y Genetica

1976-01-01

A bioassay for cell differentiation during stomatal development in barley (Hordeum vulgare L.) has been defined. It uses cell kinetics analysis to follow the temporal course of cell divisions in the developmental sequence. The rate of displacement of the divisions along the stomatal rows provides a measure of differentiation. Physical factors affecting differentiation may be tested with intact seedlings. The bioassay showed that X-ray irradiation inhibited the divisions leading to stomatal formation. The inhibition kinetics was similar to the one observed in root meristems. Chemical substances are tested by culturing excised shoots in a synthetic medium. Detached leaves responded to sucrose and light with increasing rates of stomatal divisions. Gibberellic acid (GA/sub 3/) was assayed for its effects on the growth of the leaf and the differentiation of stomata. GA/sub 3/ increased the overall length of the leaves without affecting the rates of cell division. The treated cells responded with increased elongation rates and a precocious initiation and completion of cell enlargement. GA/sub 3/ had no specific effect on stomatal differentiation.

Field measurements for low-aperture magnetic elements

International Nuclear Information System (INIS)

Mikhajlichenko, A.A.

1989-01-01

The method of the field measurements with help of bismuth wire in low aperture magnetic elements is revised. The quadrupole with permanent magnets was tested. It has aperture diameter about 4 mm and length 40 mm. Gradient about 38 kOe/cm was measured. The accuracy of the magnetic axis position definition is better than 1 μm. This method is a good kandidate for linear colider low aperture magnetic elements measurements. 7 refs.; 6 figs

Fast decoding algorithms for geometric coded apertures

International Nuclear Information System (INIS)

Byard, Kevin

2015-01-01

Fast decoding algorithms are described for the class of coded aperture designs known as geometric coded apertures which were introduced by Gourlay and Stephen. When compared to the direct decoding method, the algorithms significantly reduce the number of calculations required when performing the decoding for these apertures and hence speed up the decoding process. Experimental tests confirm the efficacy of these fast algorithms, demonstrating a speed up of approximately two to three orders of magnitude over direct decoding.

A new discrete dynamic model of ABA-induced stomatal closure predicts key feedback loops.

Directory of Open Access Journals (Sweden)

Réka Albert

2017-09-01

Full Text Available Stomata, microscopic pores in leaf surfaces through which water loss and carbon dioxide uptake occur, are closed in response to drought by the phytohormone abscisic acid (ABA. This process is vital for drought tolerance and has been the topic of extensive experimental investigation in the last decades. Although a core signaling chain has been elucidated consisting of ABA binding to receptors, which alleviates negative regulation by protein phosphatases 2C (PP2Cs of the protein kinase OPEN STOMATA 1 (OST1 and ultimately results in activation of anion channels, osmotic water loss, and stomatal closure, over 70 additional components have been identified, yet their relationships with each other and the core components are poorly elucidated. We integrated and processed hundreds of disparate observations regarding ABA signal transduction responses underlying stomatal closure into a network of 84 nodes and 156 edges and, as a result, established those relationships, including identification of a 36-node, strongly connected (feedback-rich component as well as its in- and out-components. The network's domination by a feedback-rich component may reflect a general feature of rapid signaling events. We developed a discrete dynamic model of this network and elucidated the effects of ABA plus knockout or constitutive activity of 79 nodes on both the outcome of the system (closure and the status of all internal nodes. The model, with more than 1024 system states, is far from fully determined by the available data, yet model results agree with existing experiments in 82 cases and disagree in only 17 cases, a validation rate of 75%. Our results reveal nodes that could be engineered to impact stomatal closure in a controlled fashion and also provide over 140 novel predictions for which experimental data are currently lacking. Noting the paucity of wet-bench data regarding combinatorial effects of ABA and internal node activation, we experimentally confirmed

A new discrete dynamic model of ABA-induced stomatal closure predicts key feedback loops.

Science.gov (United States)

Albert, Réka; Acharya, Biswa R; Jeon, Byeong Wook; Zañudo, Jorge G T; Zhu, Mengmeng; Osman, Karim; Assmann, Sarah M

2017-09-01

Stomata, microscopic pores in leaf surfaces through which water loss and carbon dioxide uptake occur, are closed in response to drought by the phytohormone abscisic acid (ABA). This process is vital for drought tolerance and has been the topic of extensive experimental investigation in the last decades. Although a core signaling chain has been elucidated consisting of ABA binding to receptors, which alleviates negative regulation by protein phosphatases 2C (PP2Cs) of the protein kinase OPEN STOMATA 1 (OST1) and ultimately results in activation of anion channels, osmotic water loss, and stomatal closure, over 70 additional components have been identified, yet their relationships with each other and the core components are poorly elucidated. We integrated and processed hundreds of disparate observations regarding ABA signal transduction responses underlying stomatal closure into a network of 84 nodes and 156 edges and, as a result, established those relationships, including identification of a 36-node, strongly connected (feedback-rich) component as well as its in- and out-components. The network's domination by a feedback-rich component may reflect a general feature of rapid signaling events. We developed a discrete dynamic model of this network and elucidated the effects of ABA plus knockout or constitutive activity of 79 nodes on both the outcome of the system (closure) and the status of all internal nodes. The model, with more than 1024 system states, is far from fully determined by the available data, yet model results agree with existing experiments in 82 cases and disagree in only 17 cases, a validation rate of 75%. Our results reveal nodes that could be engineered to impact stomatal closure in a controlled fashion and also provide over 140 novel predictions for which experimental data are currently lacking. Noting the paucity of wet-bench data regarding combinatorial effects of ABA and internal node activation, we experimentally confirmed several predictions

Modelling stomatal ozone flux and deposition to grassland communities across Europe

International Nuclear Information System (INIS)

Ashmore, M.R.; Bueker, P.; Emberson, L.D.; Terry, A.C.; Toet, S.

2007-01-01

Regional scale modelling of both ozone deposition and the risk of ozone impacts is poorly developed for grassland communities. This paper presents new predictions of stomatal ozone flux to grasslands at five different locations in Europe, using a mechanistic model of canopy development for productive grasslands to generate time series of leaf area index and soil water potential as inputs to the stomatal component of the DO 3 SE ozone deposition model. The parameterisation of both models was based on Lolium perenne, a dominant species of productive pasture in Europe. The modelled seasonal time course of stomatal ozone flux to both the whole canopy and to upper leaves showed large differences between climatic zones, which depended on the timing of the start of the growing season, the effect of soil water potential, and the frequency of hay cuts. Values of modelled accumulated flux indices and the AOT40 index showed a five-fold difference between locations, but the locations with the highest flux differed depending on the index used; the period contributing to the accumulation of AOT40 did not always coincide with the modelled period of active ozone canopy uptake. Use of a fixed seasonal profile of leaf area index in the flux model produced very different estimates of annual accumulated total canopy and leaf ozone flux when compared with the flux model linked to a simulation of canopy growth. Regional scale model estimates of both the risks of ozone impacts and of total ozone deposition will be inaccurate unless the effects of climate and management in modifying grass canopy growth are incorporated. - Modelled stomatal flux of ozone to productive grasslands in Europe shows different spatial and temporal variation to AOT40, and is modified by management and soil water status

Using Plant Temperature to Evaluate the Response of Stomatal Conductance to Soil Moisture Deficit

Directory of Open Access Journals (Sweden)

Ming-Han Yu

2015-10-01

Full Text Available Plant temperature is an indicator of stomatal conductance, which reflects soil moisture stresses. We explored the relationship between plant temperature and soil moisture to optimize irrigation schedules in a water-stress experiment using Firmiana platanifolia (L. f. Marsili in an incubator. Canopy temperature, leaf temperature, and stomatal conductance were measured using thermal imaging and a porometer. The results indicated that (1 stomatal conductance decreased with declines in soil moisture, and reflected average canopy temperature; (2 the variation of the leaf temperature distribution was a reliable indicator of soil moisture stress, and the temperature distribution in severely water-stressed leaves exhibited greater spatial variation than that in the presence of sufficient irrigation; (3 thermal indices (Ig and crop water stress index (CWSI were theoretically proportional to stomatal conductance (gs, Ig was certified to have linearity relationship with gs and CWSI have a logarithmic relationship with gs, and both of the two indices can be used to estimate soil moisture; and (4 thermal imaging data can reflect water status irrespective of long-term water scarcity or lack of sudden rainfall. This study applied thermal imaging methods to monitor plants and develop adaptable irrigation scheduling, which are important for the formulation of effective and economical agriculture and forestry policy.

Ferns are less dependent on passive dilution by cell expansion to coordinate leaf vein and stomatal spacing than angiosperms.

Directory of Open Access Journals (Sweden)

Madeline R Carins Murphy

Full Text Available Producing leaves with closely spaced veins is a key innovation linked to high rates of photosynthesis in angiosperms. A close geometric link between veins and stomata in angiosperms ensures that investment in enhanced venous water transport provides the strongest net carbon return to the plant. This link is underpinned by "passive dilution" via expansion of surrounding cells. However, it is not known whether this 'passive dilution' mechanism is present in plant lineages other than angiosperms and is another key feature of the angiosperms' evolutionary success. Consequently, we sought to determine whether the 'passive dilution' mechanism is; (i exclusive to the angiosperms, (ii a conserved mechanism that evolved in the common ancestor of ferns and angiosperms, or (iii has evolved continuously over time. To do this we first we assessed the plasticity of vein and stomatal density and epidermal cell size in ferns in response to light environment. We then compared the relationships between these traits found among ferns with modelled relationships that assume vein and stomatal density respond passively to epidermal cell expansion, and with those previously observed in angiosperms. Vein density, stomatal density and epidermal cell size were linked in ferns with remarkably similar relationships to those observed in angiosperms, except that fern leaves had fewer veins per stomata. However, plasticity was limited in ferns and stomatal spacing was dependent on active stomatal differentiation as well as passive cell expansion. Thus, ferns (like angiosperms appear to coordinate vein and stomatal density with epidermal cell expansion to some extent to maintain a constant ratio between veins and stomata in the leaf. The different general relationships between vein density and stomatal density in ferns and angiosperms suggests the groups have different optimum balances between the production of vein tissue dedicated to water supply and stomatal tissue for gas

Experience with TL-102M for the treatment of radiation stomatitis

International Nuclear Information System (INIS)

Nishio, Juntaro; Matsuya, Tokuzo; Inoue, Kazuo; Miyazaki, Tadashi; Maeda, Noriaki.

1984-01-01

TL-102M was administered to 14 patients who had radiation stomatitis following radiation therapy for malignant tumors in the oral cavity. Regarding the degree of overall improvement, one of the 14 patients was evaluated as ''extremely improved'', eight as ''improved'', four as ''slightly improved'', and one as ''unchanged''. None of the patients had side effects. Adherent, powdered TL-102M was easy to take for patients. Most of the patients desired to continue to take this drug because of having neither painfulness nor adhesive feeling. The usage of TL-102M could be helpful in promoting the treatment for cancer, thus suggesting that it is useful in treating radiation stomatitis. (Namekawa, K.)

Dual aperture dipole magnet with second harmonic component

Science.gov (United States)

Praeg, Walter F.

1985-01-01

An improved dual aperture dipole electromagnet includes a second-harmonic frequency magnetic guide field winding which surrounds first harmonic frequency magnetic guide field windings associated with each aperture. The second harmonic winding and the first harmonic windings cooperate to produce resultant magnetic waveforms in the apertures which have extended acceleration and shortened reset portions of electromagnet operation.

47 CFR 25.134 - Licensing provisions of Very Small Aperture Terminal (VSAT) and C-band Small Aperture Terminal...

Science.gov (United States)

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Licensing provisions of Very Small Aperture Terminal (VSAT) and C-band Small Aperture Terminal (CSAT) networks. 25.134 Section 25.134 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS...

Phenomics allows identification of genomic regions affecting maize stomatal conductance with conditional effects of water deficit and evaporative demand.

Science.gov (United States)

Prado, Santiago Alvarez; Cabrera-Bosquet, Llorenç; Grau, Antonin; Coupel-Ledru, Aude; Millet, Emilie J; Welcker, Claude; Tardieu, François

2018-02-01

Stomatal conductance is central for the trades-off between hydraulics and photosynthesis. We aimed at deciphering its genetic control and that of its responses to evaporative demand and water deficit, a nearly impossible task with gas exchanges measurements. Whole-plant stomatal conductance was estimated via inversion of the Penman-Monteith equation from data of transpiration and plant architecture collected in a phenotyping platform. We have analysed jointly 4 experiments with contrasting environmental conditions imposed to a panel of 254 maize hybrids. Estimated whole-plant stomatal conductance closely correlated with gas-exchange measurements and biomass accumulation rate. Sixteen robust quantitative trait loci (QTLs) were identified by genome wide association studies and co-located with QTLs of transpiration and biomass. Light, vapour pressure deficit, or soil water potential largely accounted for the differences in allelic effects between experiments, thereby providing strong hypotheses for mechanisms of stomatal control and a way to select relevant candidate genes among the 1-19 genes harboured by QTLs. The combination of allelic effects, as affected by environmental conditions, accounted for the variability of stomatal conductance across a range of hybrids and environmental conditions. This approach may therefore contribute to genetic analysis and prediction of stomatal control in diverse environments. © 2017 John Wiley & Sons Ltd.

Transport of Particle Swarms Through Variable Aperture Fractures

Science.gov (United States)

Boomsma, E.; Pyrak-Nolte, L. J.

2012-12-01

Particle transport through fractured rock is a key concern with the increased use of micro- and nano-size particles in consumer products as well as from other activities in the sub- and near surface (e.g. mining, industrial waste, hydraulic fracturing, etc.). While particle transport is often studied as the transport of emulsions or dispersions, particles may also enter the subsurface from leaks or seepage that lead to particle swarms. Swarms are drop-like collections of millions of colloidal-sized particles that exhibit a number of unique characteristics when compared to dispersions and emulsions. Any contaminant or engineered particle that forms a swarm can be transported farther, faster, and more cohesively in fractures than would be expected from a traditional dispersion model. In this study, the effects of several variable aperture fractures on colloidal swarm cohesiveness and evolution were studied as a swarm fell under gravity and interacted with the fracture walls. Transparent acrylic was used to fabricate synthetic fracture samples with (1) a uniform aperture, (2) a converging region followed by a uniform region (funnel shaped), (3) a uniform region followed by a diverging region (inverted funnel), and (4) a cast of a an induced fracture from a carbonate rock. All of the samples consisted of two blocks that measured 100 x 100 x 50 mm. The minimum separation between these blocks determined the nominal aperture (0.5 mm to 20 mm). During experiments a fracture was fully submerged in water and swarms were released into it. The swarms consisted of a dilute suspension of 3 micron polystyrene fluorescent beads (1% by mass) with an initial volume of 5μL. The swarms were illuminated with a green (525 nm) LED array and imaged optically with a CCD camera. The variation in fracture aperture controlled swarm behavior. Diverging apertures caused a sudden loss of confinement that resulted in a rapid change in the swarm's shape as well as a sharp increase in its velocity

Fractal characteristics of fracture roughness and aperture data

International Nuclear Information System (INIS)

Kumar, S.; Boernge, J.

1991-05-01

In this study mathematical expressions are developed for the characteristics of apertures between rough surfaces. It has shown that the correlation between the opposite surfaces influences the aperture properties and different models are presented for these different surface correlations. Fracture and apertures profiles measured from intact fractures are evaluated and it is found that they qualitatively follow the mathematically predicted trends

Calibration of circular aperture area using vision probe at inmetro

Directory of Open Access Journals (Sweden)

Costa Pedro Bastos

2016-01-01

Full Text Available Circular aperture areas are standards of high importance for the realization of photometric and radiometric measurements, where the accuracy of these measures is related to the accuracy of the circular aperture area calibrations. In order to attend the requirement for traceability was developed in Brazilian metrology institute, a methodology for circular aperture area measurement as requirements from the radiometric and photometric measurements. In the developed methodology apertures are measured by non-contact measurement through images of the aperture edges captured by a camera. These images are processed using computer vision techniques and then the values of the circular aperture area are determined.

Stomatal acclimation to vapour pressure deficit doubles transpiration of small tree seedlings with warming

DEFF Research Database (Denmark)

Marchin, Renée M.; Broadhead, Alice A.; Bostic, Laura E.

2016-01-01

chamber VPD. Warming increased mean water use of Carya by 140% and Quercus by 150%, but had no significant effect on water use of Acer. Increased water use of ring-porous species was attributed to (1) higher air T and (2) stomatal acclimation to VPD resulting in higher gs and more sensitive stomata......Future climate change is expected to increase temperature (T) and atmospheric vapour pressure deficit (VPD) in many regions, but the effect of persistent warming on plant stomatal behaviour is highly uncertain. We investigated the effect of experimental warming of 1.9-5.1 °C and increased VPD of 0.......5-1.3 kPa on transpiration and stomatal conductance (gs ) of tree seedlings in the temperate forest understory (Duke Forest, North Carolina, USA). We observed peaked responses of transpiration to VPD in all seedlings, and the optimum VPD for transpiration (Dopt ) shifted proportionally with increasing...

Synthetic aperture radar: principles and applications

International Nuclear Information System (INIS)

Khan, N.A.; Yahya, K.M.

2003-01-01

In this paper an introduction to synthetic aperture radar is presented. Synthetic aperture radar is a relatively new remote sensing platform and the technology has matured a lot in the last two decades. This paper introduces the concepts behind SAR principles as well as the major areas where this new technology has shown additional information. (author)

Differential effects of elevated air humidity on stomatal closing ability of Kalanchoë blossfeldiana between the C

NARCIS (Netherlands)

Fanourakis, Dimitrios; Hyldgaard, Benita; Gebraegziabher, Habtamu; Bouranis, Dimitris; Körner, Oliver; Nielsen, Kai Lønne; Ottosen, Carl-Otto

2017-01-01

High relative air humidity (RH ≥ 85%) impairs stomatal functionality, attenuating plant capacity to cope with abiotic stress. Previous studies were limited to C₃ species, so the RH effect on stomatal physiology of CAM plants remains unexplored. We addressed the topic through

The effect of denture stability, occlusion, oral hygiene and smoking on denture-induced stomatitis

International Nuclear Information System (INIS)

Nimri, Gadeer Mukatash

2008-01-01

This longitudinal clinical investigation was undertaken to find out the effect of denture wearing habit (day versus day and night), denture hygiene and cigarette smoking habit on the frequency of denture induced stomatitis. Comparisons were made between 240 complete denture wearers, half of whom were asked to wear their dentures at the daytime only and the other half to wear the denture day and night. All these participants were male patients with a mean age of 57.6 years who had received maxillary complete acrylic dentures for the first time. Fifty percent of the samples were smokers. A standard method for examination of the mouth and denture construction, insertion and follow up were employed. Putative risk factors (denture wearing habits, denture hygiene and smoking) were investigated. Subjects were recalled 12 months after insertion to examine the quality of the denture and the condition of the maxillary mucosa. No significant correlation was found between deterioration of stability or occlusion and type of habitual use of the dentures (P > 0.05). Fourteen percent of the cases reported with inflamed maxillary mucosa. Deterioration of retention or occlusion separately showed no correlation with the condition of the mucosa. However, associated deterioration of both stability and occlusion proved to be significantly correlated with the occurrence of denture stomatitis (P < 0.05). Denture stomatitis was significantly more frequently with subjects wearing their dentures overnight compared with those who removed them (P < 0.05). A significant correlation was also found between cigarette smoking, poor oral hygiene and the presence of denture induced stomatitis (P < 0.05). Nocturnal denture wearing habit, deficient oral and denture hygiene, and cigarette smoking are all important predisposing factors to denture-induced stomatitis, however, none of these factors was the sole cause of mucosal inflammation. (author)

Quantitative trait loci mapping for stomatal traits in interspecific ...

Indian Academy of Sciences (India)

Dr.YASODHA

seedling raising, field planting and maintenance of the mapping population. ... tereticornis and production of interspecific hybrids displaying hybrid vigour in terms of .... A total of 114, 115 and 129 SSR, ISSR and SRAP markers were generated .... stomatal traits with yield and adaptability would help to improve productivity of ...

Intraspecific variation in stomatal traits, leaf traits and physiology reflects adaptation along aridity gradients in a South African shrub.

Science.gov (United States)

Carlson, Jane E; Adams, Christopher A; Holsinger, Kent E

2016-01-01

Trait-environment relationships are commonly interpreted as evidence for local adaptation in plants. However, even when selection analyses support this interpretation, the mechanisms underlying differential benefits are often unknown. This study addresses this gap in knowledge using the broadly distributed South African shrub Protea repens. Specifically, the study examines whether broad-scale patterns of trait variation are consistent with spatial differences in selection and ecophysiology in the wild. In a common garden study of plants sourced from 19 populations, associations were measured between five morphological traits and three axes describing source climates. Trait-trait and trait-environment associations were analysed in a multi-response model. Within two focal populations in the wild, selection and path analyses were used to test associations between traits, fecundity and physiological performance. Across 19 populations in a common garden, stomatal density increased with the source population's mean annual temperature and decreased with its average amount of rainfall in midsummer. Concordantly, selection analysis in two natural populations revealed positive selection on stomatal density at the hotter, drier site, while failing to detect selection at the cooler, moister site. Dry-site plants with high stomatal density also had higher stomatal conductances, cooler leaf temperatures and higher light-saturated photosynthetic rates than those with low stomatal density, but no such relationships were present among wet-site plants. Leaf area, stomatal pore index and specific leaf area in the garden also co-varied with climate, but within-population differences were not associated with fitness in either wild population. The parallel patterns of broad-scale variation, differences in selection and differences in trait-ecophysiology relationships suggest a mechanism for adaptive differentiation in stomatal density. Densely packed stomata may improve performance by

Fast-neutron, coded-aperture imager

International Nuclear Information System (INIS)

Woolf, Richard S.; Phlips, Bernard F.; Hutcheson, Anthony L.; Wulf, Eric A.

2015-01-01

This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

Fast-neutron, coded-aperture imager

Energy Technology Data Exchange (ETDEWEB)

Woolf, Richard S., E-mail: richard.woolf@nrl.navy.mil; Phlips, Bernard F., E-mail: bernard.phlips@nrl.navy.mil; Hutcheson, Anthony L., E-mail: anthony.hutcheson@nrl.navy.mil; Wulf, Eric A., E-mail: eric.wulf@nrl.navy.mil

2015-06-01

This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

Clinical evaluation of the essential oil of "Satureja Hortensis" for the treatment of denture stomatitis

Directory of Open Access Journals (Sweden)

Ali Mohammad Sabzghabaee

2012-01-01

Full Text Available Background: The prevalence of denture stomatitis has been shown to vary from 15 to 65% in complete denture wearers. Satureja hortensis L. has been considered to have antinociceptive, anti-inflammatory, antifungal and antimicrobial activities in vitro and exhibits strong inhibitory effect on the growth of periodontal bacteria. The aim of this study was to evaluate the efficacy of a 1% gel formulation of S. hortensis essential oil for the treatment of denture stomatitis. Materials and Methods: A randomized, controlled clinical trial study was conducted on 80 patients (mean age 62.91±7.34 in two parallel groups treated either with S. hortensis essential oil 1% gel or placebo applied two times daily for two weeks. Denture stomatitis was diagnosed by clinical examination and paraclinical confirmation with sampling the palatal mucosa for Candida albicans. Data were analyzed using Chi-squared or Student′s t tests. Results: The erythematous lesions of palatal area were significantly reduced (P<0.0001 in the treatment group who applied 1% topical gel of S. hortensis essential oil and Candida colonies count were reduced significantly (P=0.001. Conclusion: Topical application of the essential oil of S. hortensis could be considered as an effective agent for the treatment of denture stomatitis.

Bovine lactoferrin and piroxicam as an adjunct treatment for lymphocytic-plasmacytic gingivitis stomatitis in cats.

Science.gov (United States)

Hung, Yi-Ping; Yang, Yi-Ping; Wang, Hsien-Chi; Liao, Jiunn-Wang; Hsu, Wei-Li; Chang, Chao-Chin; Chang, Shih-Chieh

2014-10-01

Feline lymphocytic-plasmacytic gingivitis/stomatitis (LPGS) or caudal stomatitis is an inflammatory disease that causes painfully erosive lesions and proliferations of the oral mucosa. The disease is difficult to cure and can affect cats at an early age, resulting in lifetime therapy. In this study, a new treatment using a combination of bovine lactoferrin (bLf) oral spray and oral piroxicam was investigated using a randomized double-blinded clinical trial in 13 cats with caudal stomatitis. Oral lesion grading and scoring of clinical signs were conducted during and after the trial to assess treatment outcome. Oral mucosal biopsies were used to evaluate histological changes during and after treatment. Clinical signs were significantly improved in 77% of the cats. In a 4-week study, clinical signs were considerably ameliorated by oral piroxicam during the first 2 weeks. In a 12-week study, the combined bLf oral spray and piroxicam, when compared with piroxicam alone, exhibited an enhanced effect that reduced the severity of the oral lesions (P = 0.059), while also significantly improving clinical signs (P piroxicam was safe and might be used to decrease the clinical signs of caudal stomatitis in cats. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Multi-antenna synthetic aperture radar

CERN Document Server

Wang, Wen-Qin

2013-01-01

Synthetic aperture radar (SAR) is a well-known remote sensing technique, but conventional single-antenna SAR is inherently limited by the minimum antenna area constraint. Although there are still technical issues to overcome, multi-antenna SAR offers many benefits, from improved system gain to increased degrees-of-freedom and system flexibility. Multi-Antenna Synthetic Aperture Radar explores the potential and challenges of using multi-antenna SAR in microwave remote sensing applications. These applications include high-resolution imaging, wide-swath remote sensing, ground moving target indica

Dynamic metamaterial aperture for microwave imaging

International Nuclear Information System (INIS)

Sleasman, Timothy; Imani, Mohammadreza F.; Gollub, Jonah N.; Smith, David R.

2015-01-01

We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture

Dynamic metamaterial aperture for microwave imaging

Energy Technology Data Exchange (ETDEWEB)

Sleasman, Timothy; Imani, Mohammadreza F.; Gollub, Jonah N.; Smith, David R. [Center for Metamaterials and Integrated Plasmonics, Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina, 27708 (United States)

2015-11-16

We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture.

Integrated electrochromic aperture diaphragm

Science.gov (United States)

Deutschmann, T.; Oesterschulze, E.

2014-05-01

In the last years, the triumphal march of handheld electronics with integrated cameras has opened amazing fields for small high performing optical systems. For this purpose miniaturized iris apertures are of practical importance because they are essential to control both the dynamic range of the imaging system and the depth of focus. Therefore, we invented a micro optical iris based on an electrochromic (EC) material. This material changes its absorption in response to an applied voltage. A coaxial arrangement of annular rings of the EC material is used to establish an iris aperture without need of any mechanical moving parts. The advantages of this device do not only arise from the space-saving design with a thickness of the device layer of 50μm. But it also benefits from low power consumption. In fact, its transmission state is stable in an open circuit, phrased memory effect. Only changes of the absorption require a voltage of up to 2 V. In contrast to mechanical iris apertures the absorption may be controlled on an analog scale offering the opportunity for apodization. These properties make our device the ideal candidate for battery powered and space-saving systems. We present optical measurements concerning control of the transmitted intensity and depth of focus, and studies dealing with switching times, light scattering, and stability. While the EC polymer used in this study still has limitations concerning color and contrast, the presented device features all functions of an iris aperture. In contrast to conventional devices it offers some special features. Owing to the variable chemistry of the EC material, its spectral response may be adjusted to certain applications like color filtering in different spectral regimes (UV, optical range, infrared). Furthermore, all segments may be switched individually to establish functions like spatial Fourier filtering or lateral tunable intensity filters.

[Suitability of four stomatal conductance models in agro-pastoral ecotone in North China: A case study for potato and oil sunflower.

Science.gov (United States)

Huang, Ming Xia; Wang, Jing; Tang, Jian Zhao; Yu, Qiang; Zhang, Jun; Xue, Qing Yu; Chang, Qing; Tan, Mei Xiu

2016-11-18

The suitability of four popular empirical and semi-empirical stomatal conductance models (Jarvis model, Ball-Berry model, Leuning model and Medlyn model) was evaluated based on para-llel observation data of leaf stomatal conductance, leaf net photosynthetic rate and meteorological factors during the vigorous growing period of potato and oil sunflower at Wuchuan experimental station in agro-pastoral ecotone in North China. It was found that there was a significant linear relationship between leaf stomatal conductance and leaf net photosynthetic rate for potato, whereas the linear relationship appeared weaker for oil sunflower. The results of model evaluation showed that Ball-Berry model performed best in simulating leaf stomatal conductance of potato, followed by Leuning model and Medlyn model, while Jarvis model was the last in the performance rating. The root-mean-square error (RMSE) was 0.0331, 0.0371, 0.0456 and 0.0794 mol·m -2 ·s -1 , the normalized root-mean-square error (NRMSE) was 26.8%, 30.0%, 36.9% and 64.3%, and R-squared (R 2 ) was 0.96, 0.61, 0.91 and 0.88 between simulated and observed leaf stomatal conductance of potato for Ball-Berry model, Leuning model, Medlyn model and Jarvis model, respectively. For leaf stomatal conductance of oil sunflower, Jarvis model performed slightly better than Leuning model, Ball-Berry model and Medlyn model. RMSE was 0.2221, 0.2534, 0.2547 and 0.2758 mol·m -2 ·s -1 , NRMSE was 40.3%, 46.0%, 46.2% and 50.1%, and R 2 was 0.38, 0.22, 0.23 and 0.20 between simulated and observed leaf stomatal conductance of oil sunflower for Jarvis model, Leuning model, Ball-Berry model and Medlyn model, respectively. The path analysis was conducted to identify effects of specific meteorological factors on leaf stomatal conductance. The diurnal variation of leaf stomatal conductance was principally affected by vapour pressure saturation deficit for both potato and oil sunflower. The model evaluation suggested that the stomatal

Fast-neutron, coded-aperture imager

Science.gov (United States)

Woolf, Richard S.; Phlips, Bernard F.; Hutcheson, Anthony L.; Wulf, Eric A.

2015-06-01

This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

Congenital pyriform aperture stenosis

International Nuclear Information System (INIS)

Osovsky, Micky; Aizer-Danon, Anat; Horev, Gadi; Sirota, Lea

2007-01-01

Nasal airway obstruction is a potentially life-threatening condition in the newborn. Neonates are obligatory nasal breathers. The pyriform aperture is the narrowest, most anterior bony portion of the nasal airway, and a decrease in its cross-sectional area will significantly increase nasal airway resistance. Congenital nasal pyriform aperture stenosis (CNPAS) is a rare, unusual form of nasal obstruction. It should be considered in the differential diagnosis of any neonate or infant with signs and symptoms of upper airway compromise. It is important to differentiate this level of obstruction from the more common posterior choanal stenosis or atresia. CNPAS presents with symptoms of nasal airway obstruction, which are often characterized by episodic apnea and cyclical cyanosis. (orig.)

Extended Aperture Photometry of K2 RR Lyrae stars

Science.gov (United States)

Plachy, Emese; Klagyivik, Péter; Molnár, László; Sódor, Ádám; Szabó, Róbert

2017-10-01

We present the method of the Extended Aperture Photometry (EAP) that we applied on K2 RR Lyrae stars. Our aim is to minimize the instrumental variations of attitude control maneuvers by using apertures that cover the positional changes in the field of view thus contain the stars during the whole observation. We present example light curves that we compared to the light curves from the K2 Systematics Correction (K2SC) pipeline applied on the automated Single Aperture Photometry (SAP) and on the Pre-search Data Conditioning Simple Aperture Photometry (PDCSAP) data.

Inhibition by acrolein of light-induced stomatal opening through inhibition of inward-rectifying potassium channels in Arabidopsis thaliana.

Science.gov (United States)

Islam, Md Moshiul; Ye, Wenxiu; Matsushima, Daiki; Khokon, Md Atiqur Rahman; Munemasa, Shintaro; Nakamura, Yoshimasa; Murata, Yoshiyuki

2015-01-01

Acrolein is a reactive α,β-unsaturated aldehyde derived from lipid peroxides, which are produced in plants under a variety of stress. We investigated effects of acrolein on light-induced stomatal opening using Arabidopsis thaliana. Acrolein inhibited light-induced stomatal opening in a dose-dependent manner. Acrolein at 100 μM inhibited plasma membrane inward-rectifying potassium (Kin) channels in guard cells. Acrolein at 100 μM inhibited Kin channel KAT1 expressed in a heterologous system using Xenopus leaves oocytes. These results suggest that acrolein inhibits light-induced stomatal opening through inhibition of Kin channels in guard cells.

Aperture meter for the Large Hadron Collider

International Nuclear Information System (INIS)

Mueller, G.J.; Fuchsberger, K.; Redaelli, S.

2012-01-01

The control of the high intensity beams of the CERN Large Hadron Collider (LHC) is particular challenging and requires a good modeling of the machine and monitoring of various machine parameters. During operation it is crucial to ensure a minimal distance between the beam edge and the aperture of sensitive equipment, e.g. the superconducting magnets, which in all cases must be in the shadow of the collimator's that protect the machine. Possible dangerous situations must be detected as soon as possible. In order to provide the operator with information about the current machine bottlenecks an aperture meter application was developed based on the LHC online modeling tool-chain. The calculation of available free aperture takes into account the best available optics and aperture model as well as the relevant beam measurements. This paper describes the design and integration of this application into the control environment and presents results of the usage in daily operation and from validation measurements. (authors)

Stomatal clustering in Begonia associates with the kinetics of leaf gaseous exchange and influences water use efficiency.

Science.gov (United States)

Papanatsiou, Maria; Amtmann, Anna; Blatt, Michael R

2017-04-01

Stomata are microscopic pores formed by specialized cells in the leaf epidermis and permit gaseous exchange between the interior of the leaf and the atmosphere. Stomata in most plants are separated by at least one epidermal pavement cell and, individually, overlay a single substomatal cavity within the leaf. This spacing is thought to enhance stomatal function. Yet, there are several genera naturally exhibiting stomata in clusters and therefore deviating from the one-cell spacing rule with multiple stomata overlaying a single substomatal cavity. We made use of two Begonia species to investigate whether clustering of stomata alters guard cell dynamics and gas exchange under different light and dark treatments. Begonia plebeja, which forms stomatal clusters, exhibited enhanced kinetics of stomatal conductance and CO2 assimilation upon light stimuli that in turn were translated into greater water use efficiency. Our findings emphasize the importance of spacing in stomatal clusters for gaseous exchange and plant performance under environmentally limited conditions. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

High-contrast imaging with an arbitrary aperture: Active compensation of aperture discontinuities

International Nuclear Information System (INIS)

Pueyo, Laurent; Norman, Colin

2013-01-01

We present a new method to achieve high-contrast images using segmented and/or on-axis telescopes. Our approach relies on using two sequential deformable mirrors (DMs) to compensate for the large amplitude excursions in the telescope aperture due to secondary support structures and/or segment gaps. In this configuration the parameter landscape of DM surfaces that yield high-contrast point-spread functions is not linear, and nonlinear methods are needed to find the true minimum in the optimization topology. We solve the highly nonlinear Monge-Ampere equation that is the fundamental equation describing the physics of phase-induced amplitude modulation. We determine the optimum configuration for our two sequential DM system and show that high-throughput and high-contrast solutions can be achieved using realistic surface deformations that are accessible using existing technologies. We name this process Active Compensation of Aperture Discontinuities (ACAD). We show that for geometries similar to the James Webb Space Telescope, ACAD can attain at least 10 –7 in contrast and an order of magnitude higher for both the future extremely large telescopes and on-axis architectures reminiscent of the Hubble Space Telescope. We show that the converging nonlinear mappings resulting from our DM shapes actually damp near-field diffraction artifacts in the vicinity of the discontinuities. Thus, ACAD actually lowers the chromatic ringing due to diffraction by segment gaps and struts while not amplifying the diffraction at the aperture edges beyond the Fresnel regime. This outer Fresnel ringing can be mitigated by properly designing the optical system. Consequently, ACAD is a true broadband solution to the problem of high-contrast imaging with segmented and/or on-axis apertures. We finally show that once the nonlinear solution is found, fine tuning with linear methods used in wavefront control can be applied to further contrast by another order of magnitude. Generally speaking, the

Oral cryotherapy for the prevention of high-dose melphalan-induced stomatitis in allogeneic hematopoietic stem cell transplant recipients.

Science.gov (United States)

Aisa, Yoshinobu; Mori, Takehiko; Kudo, Masumi; Yashima, Tomoko; Kondo, Sakiko; Yokoyama, Akihiro; Ikeda, Yasuo; Okamoto, Shinichiro

2005-04-01

The purpose of this study was to evaluate the efficacy of oral cryotherapy to prevent high-dose melphalan-induced stomatitis. Eighteen consecutive recipients of allogeneic hematopoietic stem cell transplant conditioned with high-dose melphalan (140 mg/m2) in combination with fludarabine alone or with fludarabine and additional chemotherapy or radiation were enrolled. The severity of stomatitis was graded according to the National Cancer Institute Common Toxicity Criteria. Patients were kept on oral cryotherapy using ice chips and ice-cold water shortly before, during, and for additional 90 min after completion of melphalan administration. Only two of 18 patients (11.1%) developed grade 2 or 3 stomatitis while six of seven patients in the historical control developed it (85.7%; P=0.001). These results suggested that oral cryotherapy could effectively prevent stomatitis caused by high-dose melphalan, and we recommend that it should be incorporated into the conditioning regimen with high-dose melphalan.

Effects of stomata clustering on leaf gas exchange.

Science.gov (United States)

Lehmann, Peter; Or, Dani

2015-09-01

A general theoretical framework for quantifying the stomatal clustering effects on leaf gaseous diffusive conductance was developed and tested. The theory accounts for stomatal spacing and interactions among 'gaseous concentration shells'. The theory was tested using the unique measurements of Dow et al. (2014) that have shown lower leaf diffusive conductance for a genotype of Arabidopsis thaliana with clustered stomata relative to uniformly distributed stomata of similar size and density. The model accounts for gaseous diffusion: through stomatal pores; via concentration shells forming at pore apertures that vary with stomata spacing and are thus altered by clustering; and across the adjacent air boundary layer. Analytical approximations were derived and validated using a numerical model for 3D diffusion equation. Stomata clustering increases the interactions among concentration shells resulting in larger diffusive resistance that may reduce fluxes by 5-15%. A similar reduction in conductance was found for clusters formed by networks of veins. The study resolves ambiguities found in the literature concerning stomata end-corrections and stomatal shape, and provides a new stomata density threshold for diffusive interactions of overlapping vapor shells. The predicted reduction in gaseous exchange due to clustering, suggests that guard cell function is impaired, limiting stomatal aperture opening. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

A Two-Big-Leaf Model for Canopy Temperature, Photosynthesis, and Stomatal Conductance.

Science.gov (United States)

Dai, Yongjiu; Dickinson, Robert E.; Wang, Ying-Ping

2004-06-01

The energy exchange, evapotranspiration, and carbon exchange by plant canopies depend on leaf stomatal control. The treatment of this control has been required by land components of climate and carbon models. Physiological models can be used to simulate the responses of stomatal conductance to changes in atmospheric and soil environments. Big-leaf models that treat a canopy as a single leaf tend to overestimate fluxes of CO2 and water vapor. Models that differentiate between sunlit and shaded leaves largely overcome these problems.A one-layered, two-big-leaf submodel for photosynthesis, stomatal conductance, leaf temperature, and energy fluxes is presented in this paper. It includes 1) an improved two stream approximation model of radiation transfer of the canopy, with attention to singularities in its solution and with separate integrations of radiation absorption by sunlit and shaded fractions of canopy; 2) a photosynthesis stomatal conductance model for sunlit and shaded leaves separately, and for the simultaneous transfers of CO2 and water vapor into and out of the leaf—leaf physiological properties (i.e., leaf nitrogen concentration, maximum potential electron transport rate, and hence photosynthetic capacity) vary throughout the plant canopy in response to the radiation weight time-mean profile of photosynthetically active radiation (PAR), and the soil water limitation is applied to both maximum rates of leaf carbon uptake by Rubisco and electron transport, and the model scales up from leaf to canopy separately for all sunlit and shaded leaves; 3) a well-built quasi-Newton Raphson method for simultaneous solution of temperatures of the sunlit and shaded leaves.The model was incorporated into the Common Land Model (CLM) and is denoted CLM 2L. It was driven with observational atmospheric forcing from two forest sites [Anglo-Brazilian Amazonian Climate Observation Study (ABRACOS) and Boreal Ecosystem Atmosphere Study (BOREAS)] for 2 yr of simulation. The

Arabidopsis YAK1 regulates abscisic acid response and drought resistance.

Science.gov (United States)

Kim, Dongjin; Ntui, Valentine Otang; Xiong, Liming

2016-07-01

Abscisic acid (ABA) is an important phytohormone that controls several plant processes such as seed germination, seedling growth, and abiotic stress response. Here, we report that AtYak1 plays an important role in ABA signaling and postgermination growth in Arabidopsis. AtYak1 knockout mutant plants were hyposensitive to ABA inhibition of seed germination, cotyledon greening, seedling growth, and stomatal movement. atyak1-1 mutant plants display reduced drought stress resistance, as evidenced by water loss rate and survival rate. Molecular genetic analysis revealed that AtYak1 deficiency led to elevated expression of stomatal-related gene, MYB60, and down-regulation of several stress-responsive genes. Altogether, these results indicate that AtYak1 plays a role as a positive regulator in ABA-mediated drought response in Arabidopsis. © 2016 Federation of European Biochemical Societies.

Arabidopsis YAK1 regulates abscisic acid response and drought resistance

KAUST Repository

Kim, Dongjin

2016-06-06

Abscisic acid (ABA) is an important phytohormone that controls several plant processes such as seed germination, seedling growth, and abiotic stress response. Here, we report that AtYak1 plays an important role in ABA signaling and postgermination growth in Arabidopsis. AtYak1 knockout mutant plants were hyposensitive to ABA inhibition of seed germination, cotyledon greening, seedling growth, and stomatal movement. atyak1-1 mutant plants display reduced drought stress resistance, as evidenced by water loss rate and survival rate. Molecular genetic analysis revealed that AtYak1 deficiency led to elevated expression of stomatal-related gene, MYB60, and down-regulation of several stress-responsive genes. Altogether, these results indicate that AtYak1 plays a role as a positive regulator in ABA-mediated drought response in Arabidopsis. © 2016 Federation of European Biochemical Societies.

Extended Aperture Photometry of K2 RR Lyrae stars

Directory of Open Access Journals (Sweden)

Plachy Emese

2017-01-01

Full Text Available We present the method of the Extended Aperture Photometry (EAP that we applied on K2 RR Lyrae stars. Our aim is to minimize the instrumental variations of attitude control maneuvers by using apertures that cover the positional changes in the field of view thus contain the stars during the whole observation. We present example light curves that we compared to the light curves from the K2 Systematics Correction (K2SC pipeline applied on the automated Single Aperture Photometry (SAP and on the Pre-search Data Conditioning Simple Aperture Photometry (PDCSAP data.

Influence of coma aberration on aperture averaged scintillations in oceanic turbulence

Science.gov (United States)

Luo, Yujuan; Ji, Xiaoling; Yu, Hong

2018-01-01

The influence of coma aberration on aperture averaged scintillations in oceanic turbulence is studied in detail by using the numerical simulation method. In general, in weak oceanic turbulence, the aperture averaged scintillation can be effectively suppressed by means of the coma aberration, and the aperture averaged scintillation decreases as the coma aberration coefficient increases. However, in moderate and strong oceanic turbulence the influence of coma aberration on aperture averaged scintillations can be ignored. In addition, the aperture averaged scintillation dominated by salinity-induced turbulence is larger than that dominated by temperature-induced turbulence. In particular, it is shown that for coma-aberrated Gaussian beams, the behavior of aperture averaged scintillation index is quite different from the behavior of point scintillation index, and the aperture averaged scintillation index is more suitable for characterizing scintillations in practice.

Large-aperture hybrid photo-detector

International Nuclear Information System (INIS)

Kawai, Y.; Nakayama, H.; Kusaka, A.; Kakuno, H.; Abe, T.; Iwasaki, M.; Aihara, H.; Tanaka, M.; Shiozawa, M.; Kyushima, H.; Suyama, M.

2007-01-01

We have developed the first complete large-aperture (13-inch diameter) hybrid photo-detector (HPD). The withstanding voltage problem has been overcome and we were able to attain an HPD operating voltage of +20 kV. Adoption of our newly developed backside illumination avalanche diode (AD) was also critical in successfully countering the additional problem of an increase in AD leakage after the activation process. We observed single photon signal timing jitter of under 450 ps in FWHM, electron transit time of ∼12 ns, and clear pulse height separation up to several photoelectron peaks, all greatly superior to the performance of any conventional large-aperture photomultiplier tubes (PMTs). In addition, our HPD has a much simpler structure than conventional large-aperture PMTs, which simplifies mass production and lowers manufacturing cost. We believe that these attributes position our HPD as the most suitable photo-detector for the next generation mega-ton class water-Cherenkov detector, which is expected to be more than 20x larger than the Super-Kamiokande (SK) detector

Applicability of common stomatal conductance models in maize under varying soil moisture conditions.

Science.gov (United States)

Wang, Qiuling; He, Qijin; Zhou, Guangsheng

2018-07-01

In the context of climate warming, the varying soil moisture caused by precipitation pattern change will affect the applicability of stomatal conductance models, thereby affecting the simulation accuracy of carbon-nitrogen-water cycles in ecosystems. We studied the applicability of four common stomatal conductance models including Jarvis, Ball-Woodrow-Berry (BWB), Ball-Berry-Leuning (BBL) and unified stomatal optimization (USO) models based on summer maize leaf gas exchange data from a soil moisture consecutive decrease manipulation experiment. The results showed that the USO model performed best, followed by the BBL model, BWB model, and the Jarvis model performed worst under varying soil moisture conditions. The effects of soil moisture made a difference in the relative performance among the models. By introducing a water response function, the performance of the Jarvis, BWB, and USO models improved, which decreased the normalized root mean square error (NRMSE) by 15.7%, 16.6% and 3.9%, respectively; however, the performance of the BBL model was negative, which increased the NRMSE by 5.3%. It was observed that the models of Jarvis, BWB, BBL and USO were applicable within different ranges of soil relative water content (i.e., 55%-65%, 56%-67%, 37%-79% and 37%-95%, respectively) based on the 95% confidence limits. Moreover, introducing a water response function, the applicability of the Jarvis and BWB models improved. The USO model performed best with or without introducing the water response function and was applicable under varying soil moisture conditions. Our results provide a basis for selecting appropriate stomatal conductance models under drought conditions. Copyright © 2018 Elsevier B.V. All rights reserved.

Study on preventive effects of i.v. administration of flavin adenine dinucleotide (FAD) before irradiation on radiation stomatitis

International Nuclear Information System (INIS)

Nagai, Masao; Houzawa, Jiro; Hakamada, Masaru

1984-01-01

In order to compare the preventive effect on radiation stomatitis, flavin adenine dinucleotide (FAD) or vitamin C was administered intravenously until the blood level reached the maximum at the time of irradiation. Thirtyfive patients with cranial or cervical tumors were allocated into the group with FAD (15), the group with vitamin C (10), and the group with irradiation alone (10). The incidence of stomititis was significantly lower and the number of patients in whom the drug was withdrawn due to stomatitis was extremely smaller in the group with FAD than in the other groups. FAD administered before irradiation was considered very useful in preventing radiation stomatitis. (Namekawa, K.)

Plester sariawan efektif dalam mempercepat penyembuhan stomatitis aftosa rekuren dan ulkus traumatikus

Directory of Open Access Journals (Sweden)

Rahmi Amtha

2017-12-01

Full Text Available Mouth ulcer plaster is effective in accelerating the healing of recurrent aphthous stomatitis and traumatic ulcers. Recurrent aphthous stomatitis (RAS is one of the most commonly occurring oral diseases. The prevalence of oral ulceration worldwide is 4%, with RAS having the largest proportion (25%. Recurrent aphthous stomatitis is oral ulceration which has a self-limiting disease, but the specific medication to reduce pain caused by lesion is still less varied nowadays. This study aimed to examine the differences in the effectiveness between topical application of hyaluronic acid (HA, mouth ulcer plaster (MUP and 0.1% triamcinolone acetonide (TA as a positive control in the healing of RAS and traumatic ulcers (TU. This was a quasi-experimental study by measuring the lesion diameter as well as visual analogue scale (VAS pre- and post-administration of three types of medication. Kruskal-walis test results show that there are differences in effectiveness (p=0.000 of the three types of medication to cure RAS and TU. There are signicant differences in the reduction of RAS and TU lesion diameter (p = 0.015 and VAS (p = 0.038 with the use of HA and MUP on the 4th day. There is no signicant difference in effectiveness (diameter and VAS of MUP and TA medication on the fourth day (p = 0.880 and p = 1.000 respectively. There is no signicant difference among HA, MUP and TA on the healing of the lesions on the seventh day (p>0.05. It can be concluded that the effectiveness of MUP is similar to that of topical medications containing corticosteroids in the healing of RAS and traumatic ulcers. ABSTRAK Stomatitis aftosa rekuren (SAR merupakan salah satu penyakit mulut yang paling umum terjadi. Prevalensi ulserasi mulut di seluruh dunia adalah 4%, dengan SAR menempati urutan terbesar yaitu 25%. Stomatitis aftosa rekuren merupakan ulserasi mulut yang memiliki self-limiting disease, namun sediaan obat yang spesifik untuk mengurangi rasa sakit yang

Chlorella induces stomatal closure via NADPH oxidase-dependent ROS production and its effects on instantaneous water use efficiency in Vicia faba.

Directory of Open Access Journals (Sweden)

Yan Li

Full Text Available Reactive oxygen species (ROS have been established to participate in stomatal closure induced by live microbes and microbe-associated molecular patterns (MAMPs. Chlorella as a beneficial microorganism can be expected to trigger stomatal closure via ROS production. Here, we reported that Chlorella induced stomatal closure in a dose-and time-dependent manner in epidermal peels of Vicia faba. Using pharmacological methods in this work, we found that the Chlorella-induced stomatal closure was almost completely abolished by a hydrogen peroxide (H2O2 scavenger, catalase (CAT, significantly suppressed by an NADPH oxidase inhibitor, diphenylene iodonium chloride (DPI, and slightly affected by a peroxidase inhibitor, salicylhydroxamic acid (SHAM, suggesting that ROS production involved in Chlorella-induced stomatal closure is mainly mediated by DPI-sensitive NADPH oxidase. Additionally, Exogenous application of optimal concentrations of Chlorella suspension improved instantaneous water use efficiency (WUEi in Vicia faba via a reduction in leaf transpiration rate (E without a parallel reduction in net photosynthetic rate (Pn assessed by gas-exchange measurements. The chlorophyll fluorescence and content analysis further demonstrated that short-term use of Chlorella did not influence plant photosynthetic reactions center. These results preliminarily reveal that Chlorella can trigger stomatal closure via NADPH oxidase-dependent ROS production in epidermal strips and improve WUEi in leave levels.

Direct aperture optimization: A turnkey solution for step-and-shoot IMRT

International Nuclear Information System (INIS)

Shepard, D.M.; Earl, M.A.; Li, X.A.; Naqvi, S.; Yu, C.

2002-01-01

IMRT treatment plans for step-and-shoot delivery have traditionally been produced through the optimization of intensity distributions (or maps) for each beam angle. The optimization step is followed by the application of a leaf-sequencing algorithm that translates each intensity map into a set of deliverable aperture shapes. In this article, we introduce an automated planning system in which we bypass the traditional intensity optimization, and instead directly optimize the shapes and the weights of the apertures. We call this approach 'direct aperture optimization'. This technique allows the user to specify the maximum number of apertures per beam direction, and hence provides significant control over the complexity of the treatment delivery. This is possible because the machine dependent delivery constraints imposed by the MLC are enforced within the aperture optimization algorithm rather than in a separate leaf-sequencing step. The leaf settings and the aperture intensities are optimized simultaneously using a simulated annealing algorithm. We have tested direct aperture optimization on a variety of patient cases using the EGS4/BEAM Monte Carlo package for our dose calculation engine. The results demonstrate that direct aperture optimization can produce highly conformal step-and-shoot treatment plans using only three to five apertures per beam direction. As compared with traditional optimization strategies, our studies demonstrate that direct aperture optimization can result in a significant reduction in both the number of beam segments and the number of monitor units. Direct aperture optimization therefore produces highly efficient treatment deliveries that maintain the full dosimetric benefits of IMRT

Stomatal responses to CO2 during a diel Crassulacean acid metabolism cycle in Kalanchoe daigremontiana and Kalanchoe pinnata.

Science.gov (United States)

von Caemmerer, Susanne; Griffiths, Howard

2009-05-01

To investigate the diurnal variation of stomatal sensitivity to CO2, stomatal response to a 30 min pulse of low CO2 was measured four times during a 24 h time-course in two Crassulacean acid metabolism (CAM) species Kalanchoe daigremontiana and Kalanchoe pinnata, which vary in the degree of succulence, and hence, expression and commitment to CAM. In both species, stomata opened in response to a reduction in pCO2 in the dark and in the latter half of the light period, and thus in CAM species, chloroplast photosynthesis is not required for the stomatal response to low pCO2. Stomata did not respond to a decreased pCO2 in K. daigremontiana in the light when stomata were closed, even when the supply of internal CO2 was experimentally reduced. We conclude that stomatal closure during phase III is not solely mediated by high internal pCO2, and suggest that in CAM species the diurnal variability in the responsiveness of stomata to pCO2 could be explained by hypothesizing the existence of a single CO2 sensor which interacts with other signalling pathways. When not perturbed by low pCO2, CO2 assimilation rate and stomatal conductance were correlated both in the light and in the dark in both species.

Multi-aperture digital coherent combining for free-space optical communication receivers.

Science.gov (United States)

Geisler, David J; Yarnall, Timothy M; Stevens, Mark L; Schieler, Curt M; Robinson, Bryan S; Hamilton, Scott A

2016-06-13

Space-to-ground optical communication systems can benefit from reducing the size, weight, and power profiles of space terminals. One way of reducing the required power-aperture product on a space platform is to implement effective, but costly, single-aperture ground terminals with large collection areas. In contrast, we present a ground terminal receiver architecture in which many small less-expensive apertures are efficiently combined to create a large effective aperture while maintaining excellent receiver sensitivity. This is accomplished via coherent detection behind each aperture followed by digitization. The digitized signals are then combined in a digital signal processing chain. Experimental results demonstrate lossless coherent combining of four lasercom signals, at power levels below 0.1 photons/bit/aperture.

Changes in the physiological activity of soybean (Glycine max L. Merr. under the influence of exogenous growth regulators

Directory of Open Access Journals (Sweden)

Anna Nowak

2015-07-01

Full Text Available In a two-year pot experiment (2008–2009 conducted at the Vegetation Hall, West Pomeranian University of Technology in Szczecin, we investigated the influence of exogenous growth regulators, i.e. indole-3-butyric acid (IBA and 6-benzylaminopurine (BAP and their mixture, on the activity of gas exchange and selected physiological features of soybeans (Glycine max L. Merr.. The experimental factors included the following Polish soybean cultivars: ‘Aldana’, ‘Progres’ and ‘Jutro’. During plant growth, CO2 assimilation (A, transpiration rate (E, stomatal conductance (gs, and substomatal CO2 concentration (ci were determined. Two soybean cultivars, i.e. ‘Jutro’ and ‘Progres’, showed a significant increase in the intensity of assimilation and transpiration after using all kinds of growth regulators as compared with the control plants. It was found that the ‘Jutro’ cultivar, after using a mixture of growth regulators (IBA + BAP, was characterized by the significantly highest CO2 assimilation (A and transpiration (E as well as the highest stomatal conductance (gs. The ‘Aldana’ cultivar, on the other hand, responded by a significant reduction in the transpiration rate, stomatal conductance and subsomatal CO2 concentration. The spraying of the plants with exogenous growth regulators had a significant influence on the increase in the number of stomata and stomatal pore length, mostly on the lower epidermis of the lamina. It was also found that plants from the ‘Jutro’ and ‘Aldana’ cultivars sprayed with IBA and IBA + BAP were characterized by the highest yield, as compared with the control plants. In the case of the ‘Jutro’ cultivar, after using the growth regulators, a positive correlation was observed between the assimilation and transpiration rates and the length of stomata, which in consequence produced increased yields.

The small ethylene response factor ERF96 is involved in the regulation of the abscisic acid response in Arabidopsis

Directory of Open Access Journals (Sweden)

Xiaoping eWang

2015-11-01

that water loss in ERF96 overexpression plants was slower than that in Col wild type plants. Stomatal closure assays indicated that ERF96 overexpression plants had reduced stomatal aperture in the presence of ABA. Taken together, our results suggest that AtERF96 positively regulates ABA responses in Arabidopsis.

Differences in the response sensitivity of stomatal index to atmospheric CO2 among four genera of Cupressaceae conifers.

Science.gov (United States)

Haworth, Matthew; Heath, James; McElwain, Jennifer C

2010-03-01

The inverse relationship between stomatal density (SD: number of stomata per mm(2) leaf area) and atmospheric concentration of CO2 ([CO2]) permits the use of plants as proxies of palaeo-atmospheric CO2. Many stomatal reconstructions of palaeo-[CO2] are based upon multiple fossil species. However, it is unclear how plants respond to [CO2] across genus, family or ecotype in terms of SD or stomatal index (SI: ratio of stomata to epidermal cells). This study analysed the stomatal numbers of conifers from the ancient family Cupressaceae, in order to examine the nature of the SI-[CO2] relationship, and potential implications for stomatal reconstructions of palaeo-[CO2]. Methods Stomatal frequency measurements were taken from historical herbarium specimens of Athrotaxis cupressoides, Tetraclinis articulata and four Callitris species, and live A. cupressoides grown under CO2-enrichment (370, 470, 570 and 670 p.p.m. CO2). T. articulata, C. columnaris and C. rhomboidea displayed significant reductions in SI with rising [CO2]; by contrast, A. cupressoides, C. preissii and C. oblonga show no response in SI. However, A. cupressoides does reduce SI to increases in [CO2] above current ambient (approx. 380 p.p.m. CO2). This dataset suggests that a shared consistent SI-[CO2] relationship is not apparent across the genus Callitris. Conclusions The present findings suggest that it is not possible to generalize how conifer species respond to fluctuations in [CO2] based upon taxonomic relatedness or habitat. This apparent lack of a consistent response, in conjunction with high variability in SI, indicates that reconstructions of absolute palaeo-[CO2] based at the genus level, or upon multiple species for discrete intervals of time are not as reliable as those based on a single or multiple temporally overlapping species.

Relationship between ammonia stomatal compensation point and nitrogen metabolism in arable crops: Current status of knowledge and potential modelling approaches

International Nuclear Information System (INIS)

Massad, Raia Silvia; Loubet, Benjamin; Tuzet, Andree; Cellier, Pierre

2008-01-01

The ammonia stomatal compensation point of plants is determined by leaf temperature, ammonium concentration ([NH 4 + ] apo ) and pH of the apoplastic solution. The later two depend on the adjacent cells metabolism and on leaf inputs and outputs through the xylem and phloem. Until now only empirical models have been designed to model the ammonia stomatal compensation point, except the model of Riedo et al. (2002. Coupling soil-plant-atmosphere exchange of ammonia with ecosystem functioning in grasslands. Ecological Modelling 158, 83-110), which represents the exchanges between the plant's nitrogen pools. The first step to model the ammonia stomatal compensation point is to adequately model [NH 4 + ] apo . This [NH 4 + ] apo has been studied experimentally, but there are currently no process-based quantitative models describing its relation to plant metabolism and environmental conditions. This study summarizes the processes involved in determining the ammonia stomatal compensation point at the leaf scale and qualitatively evaluates the ability of existing whole plant N and C models to include a model for [NH 4 + ] apo . - A model for ammonia stomatal compensation point at the leaf level scale was developed

Diffraction contrast imaging using virtual apertures

International Nuclear Information System (INIS)

Gammer, Christoph; Burak Ozdol, V.; Liebscher, Christian H.; Minor, Andrew M.

2015-01-01

Two methods on how to obtain the full diffraction information from a sample region and the associated reconstruction of images or diffraction patterns using virtual apertures are demonstrated. In a STEM-based approach, diffraction patterns are recorded for each beam position using a small probe convergence angle. Similarly, a tilt series of TEM dark-field images is acquired. The resulting datasets allow the reconstruction of either electron diffraction patterns, or bright-, dark- or annular dark-field images using virtual apertures. The experimental procedures of both methods are presented in the paper and are applied to a precipitation strengthened and creep deformed ferritic alloy with a complex microstructure. The reconstructed virtual images are compared with conventional TEM images. The major advantage is that arbitrarily shaped virtual apertures generated with image processing software can be designed without facing any physical limitations. In addition, any virtual detector that is specifically designed according to the underlying crystal structure can be created to optimize image contrast. - Highlights: • A dataset containing all structural information of a given position is recorded. • The dataset allows reconstruction of virtual diffraction patterns or images. • Specific virtual apertures are designed to image precipitates in a complex alloy. • Virtual diffraction patterns from arbitrarily small regions can be established. • Using STEM diffraction to record the dataset is more efficient than TEM dark-field

Coded aperture solution for improving the performance of traffic enforcement cameras

Science.gov (United States)

Masoudifar, Mina; Pourreza, Hamid Reza

2016-10-01

A coded aperture camera is proposed for automatic license plate recognition (ALPR) systems. It captures images using a noncircular aperture. The aperture pattern is designed for the rapid acquisition of high-resolution images while preserving high spatial frequencies of defocused regions. It is obtained by minimizing an objective function, which computes the expected value of perceptual deblurring error. The imaging conditions and camera sensor specifications are also considered in the proposed function. The designed aperture improves the depth of field (DoF) and subsequently ALPR performance. The captured images can be directly analyzed by the ALPR software up to a specific depth, which is 13 m in our case, though it is 11 m for the circular aperture. Moreover, since the deblurring results of images captured by our aperture yield fewer artifacts than those captured by the circular aperture, images can be first deblurred and then analyzed by the ALPR software. In this way, the DoF and recognition rate can be improved at the same time. Our case study shows that the proposed camera can improve the DoF up to 17 m while it is limited to 11 m in the conventional aperture.

Pattern Synthesis of Dual-band Shared Aperture Interleaved Linear Antenna Arrays

Directory of Open Access Journals (Sweden)

H. Guo

2014-09-01

Full Text Available This paper presents an approach to improve the efficiency of an array aperture by interleaving two different arrays in the same aperture area. Two sub-arrays working at different frequencies are interleaved in the same linear aperture area. The available aperture area is efficiently used. The element positions of antenna array are optimized by using Invasive Weed Optimization (IWO to reduce the peak side lobe level (PSLL of the radiation pattern. To overcome the shortness of traditional methods which can only fulfill the design of shared aperture antenna array working at the same frequency, this method can achieve the design of dual-band antenna array with wide working frequency range. Simulation results show that the proposed method is feasible and efficient in the synthesis of dual-band shared aperture antenna array.

Stomatal distribution, stomatal density and daily leaf movement in Acacia aroma (Leguminosae Distribución y densidad estomática y movimiento diario de la hoja en Acacia aroma (Leguminosae

Directory of Open Access Journals (Sweden)

Marcelo P. Hernández

2010-12-01

Full Text Available Acacia aroma Gillies ex Hook. & Arn. grows in the Chacoan and Yungas Biogeographic Provinces, Argentina. It has numerous medicinal applications, sweet and edible fruits, and it may be used as forage. The objective of the present contribution was to analyse the stomatal distribution and stomatal density on the secondary leaflet surfaces, in different parts of the leaf, and at different tree crown levels, establishing the leaf movement and environmental condition relationships. The work was performed with fresh material and herbarium specimens, using conventional anatomical techniques. Stomatal distribution on the secondary leaflet surfaces was established, and differences in stomatal density among basal, medium and apical leaflets were found. A decrease in stomatal density from the lower level to the upper level of the tree crown would be connected with that. The stomatal distribution and density appear related to the secondary leaflet shape and its position on the secondary rachis, interacting with the daily secondary leaflets and leaf movement, and the weather conditions. It is interesting that the medium value of stomata density were found in the middle part of the leaf and at the middle level of the tree crown. Original illustrations are given.Acacia aroma crece en las Provincias Biogeográficas Chaqueña y de las Yungas, Argentina. Este árbol posee numerosas aplicaciones en medicina popular, sus frutos son comestibles y puede ser usada como forraje. Los objetivos de la presente contribución fueron: establecer la distribución y densidad de los estomas en el folíolo secundario, en distintos folíolos secundarios de la misma hoja y en los folíolos secundarios de las hojas de la parte basal, media y superior de la copa del árbol, estableciendo relaciones con el movimiento diario de las hojas y condiciones ambientales. Para el estudio se utilizó material fresco y ejemplares de herbario empleando técnicas de anatomía convencionales. Se

Solar energy apparatus with apertured shield

Science.gov (United States)

Collings, Roger J. (Inventor); Bannon, David G. (Inventor)

1989-01-01

A protective apertured shield for use about an inlet to a solar apparatus which includesd a cavity receiver for absorbing concentrated solar energy. A rigid support truss assembly is fixed to the periphery of the inlet and projects radially inwardly therefrom to define a generally central aperture area through which solar radiation can pass into the cavity receiver. A non-structural, laminated blanket is spread over the rigid support truss in such a manner as to define an outer surface area and an inner surface area diverging radially outwardly from the central aperture area toward the periphery of the inlet. The outer surface area faces away from the inlet and the inner surface area faces toward the cavity receiver. The laminated blanket includes at least one layer of material, such as ceramic fiber fabric, having high infra-red emittance and low solar absorption properties, and another layer, such as metallic foil, of low infra-red emittance properties.

Class of near-perfect coded apertures

International Nuclear Information System (INIS)

Cannon, T.M.; Fenimore, E.E.

1978-01-01

The encoding/decoding method produces artifacts, which even in the absence of quantum noise, restrict the quality of the reconstructed image. This is true of most correlation-type methods. If the decoding procedure is of the deconvolution variety, small terms in the transfer function of the aperture can lead to excessive noise in the reconstructed image. The authors propose to circumvent both of these problems by use of a uniformly redundant array (URA) as the coded aperture in conjunction with a special correlation decoding method. The correlation of the decoding array with the aperture results in a delta function with deterministically zero sidelobes. It is shown that the reconstructed image in the URA system contains virtually uniform noise regardless of the structure in the original source. Therefore, the improvement over a single pinhole camera will be relatively larger for the brighter points in the source than for the low intensity points. 12 refs

Effect of Light Quality on Stomatal Opening in Leaves of Xanthium strumarium L.

Science.gov (United States)

Sharkey, T D; Raschke, K

1981-11-01

Flux response curves were determined at 16 wavelengths of light for the conductance for water vapor of the lower epidermis of detached leaves of Xanthium strumarium L. An action spectrum of stomatal opening resulted in which blue light (wavelengths between 430 and 460 nanometers) was nearly ten times more effective than red light (wavelengths between 630 and 680 nanometers) in producing a conductance of 15 centimoles per square meter per second. Stomata responded only slightly to green light. An action spectrum of stomatal responses to red light corresponded to that of CO(2) assimilation; the inhibitors of photosynthetic electron transport, cyanazine (2-chloro-4[1-cyano-1-methylethylamino]-6-ethylamino-s-triazine) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea, eliminated the response to red light. This indicates that light absorption by chlorophyll is the cause of stomatal sensitivity to red light. Determination of flux response curves on leaves in the normal position (upper epidermis facing the light) or in the inverted position (lower epidermis facing the light) led to the conclusion that the photoreceptors for blue as well as for red light are located on or near the surfaces of the leaves; presumably they are in the guard cells themselves.

JST Thesaurus Headwords and Synonyms: vesicular stomatitis virus [MeCab user dictionary for science technology term[Archive

Lifescience Database Archive (English)

Full Text Available MeCab user dictionary for science technology term vesicular stomatitis virus 名詞 一般 ...* * * * 水疱性口内炎ウイルス スイホウセイコウナイエンウイルス スイホーセイコーナイエンウイルス Thesaurus2015 200906056003651861 C LS07 UNKNOWN_2 vesicular stomatitis virus

Synthetic aperture design for increased SAR image rate

Science.gov (United States)

Bielek, Timothy P [Albuquerque, NM; Thompson, Douglas G [Albuqerque, NM; Walker, Bruce C [Albuquerque, NM

2009-03-03

High resolution SAR images of a target scene at near video rates can be produced by using overlapped, but nevertheless, full-size synthetic apertures. The SAR images, which respectively correspond to the apertures, can be analyzed in sequence to permit detection of movement in the target scene.

An ancestral stomatal patterning module revealed in the non-vascular land plant Physcomitrella patens

Science.gov (United States)

Chater, Caspar C.; Kamisugi, Yasuko

2016-01-01

The patterning of stomata plays a vital role in plant development and has emerged as a paradigm for the role of peptide signals in the spatial control of cellular differentiation. Research in Arabidopsis has identified a series of epidermal patterning factors (EPFs), which interact with an array of membrane-localised receptors and associated proteins (encoded by ERECTA and TMM genes) to control stomatal density and distribution. However, although it is well-established that stomata arose very early in the evolution of land plants, until now it has been unclear whether the established angiosperm stomatal patterning system represented by the EPF/TMM/ERECTA module reflects a conserved, universal mechanism in the plant kingdom. Here, we use molecular genetics to show that the moss Physcomitrella patens has conserved homologues of angiosperm EPF, TMM and at least one ERECTA gene that function together to permit the correct patterning of stomata and that, moreover, elements of the module retain function when transferred to Arabidopsis. Our data characterise the stomatal patterning system in an evolutionarily distinct branch of plants and support the hypothesis that the EPF/TMM/ERECTA module represents an ancient patterning system. PMID:27407102

Relationship between ammonia stomatal compensation point and nitrogen metabolism in arable crops: Current status of knowledge and potential modelling approaches

Energy Technology Data Exchange (ETDEWEB)

Massad, Raia Silvia [Institut National de la Recherche Agronomique (INRA), Environnement et Grandes Cultures, 78850 Thiverval-Grignon (France)], E-mail: massad@grignon.inra.fr; Loubet, Benjamin; Tuzet, Andree; Cellier, Pierre [Institut National de la Recherche Agronomique (INRA), Environnement et Grandes Cultures, 78850 Thiverval-Grignon (France)

2008-08-15

The ammonia stomatal compensation point of plants is determined by leaf temperature, ammonium concentration ([NH{sub 4}{sup +}]{sub apo}) and pH of the apoplastic solution. The later two depend on the adjacent cells metabolism and on leaf inputs and outputs through the xylem and phloem. Until now only empirical models have been designed to model the ammonia stomatal compensation point, except the model of Riedo et al. (2002. Coupling soil-plant-atmosphere exchange of ammonia with ecosystem functioning in grasslands. Ecological Modelling 158, 83-110), which represents the exchanges between the plant's nitrogen pools. The first step to model the ammonia stomatal compensation point is to adequately model [NH{sub 4}{sup +}]{sub apo}. This [NH{sub 4}{sup +}]{sub apo} has been studied experimentally, but there are currently no process-based quantitative models describing its relation to plant metabolism and environmental conditions. This study summarizes the processes involved in determining the ammonia stomatal compensation point at the leaf scale and qualitatively evaluates the ability of existing whole plant N and C models to include a model for [NH{sub 4}{sup +}]{sub apo}. - A model for ammonia stomatal compensation point at the leaf level scale was developed.

Tree density and permafrost thaw depth influence water limitations on stomatal conductance in Siberian Arctic boreal forests

Science.gov (United States)

Kropp, H.; Loranty, M. M.; Natali, S.; Kholodov, A. L.; Alexander, H. D.; Zimov, N.

2017-12-01

Boreal forests may experience increased water stress under global climate change as rising air temperatures increase evaporative demand and decrease soil moisture. Increases in plant water stress can decrease stomatal conductance, and ultimately, decrease primary productivity. A large portion of boreal forests are located in Siberia, and are dominated by deciduous needleleaf trees, Larix spp. We investigated the variability and drivers of canopy stomatal conductance in upland Larix stands with different stand density that arose from differing fire severity. Our measurements focus on an open canopy stand with low tree density and deep permafrost thaw depth, and a closed canopy stand with high tree density and shallow permafrost thaw depth. We measured canopy stomatal conductance, soil moisture, and micrometeorological variables. Our results demonstrate that canopy stomatal conductance was significantly lower in the closed canopy stand with a significantly higher sensitivity to increases in atmospheric evaporative demand. Canopy stomatal conductance in both stands was tightly coupled to precipitation that occurred over the previous week; however, the closed canopy stand showed a significantly greater sensitivity to increases in precipitation compared to the open canopy stand. Differences in access to deep versus shallow soil moisture and the physical characteristics of the soil profile likely contribute to differences in sensitivity to precipitation between the two stands. Our results indicate that Larix primary productivity may be highly sensitive to changes in evaporative demand and soil moisture that can result of global climate change. However, the effect of increasing air temperatures and changes in precipitation will differ significantly depending on stand density, thaw depth, and the hydraulic characteristics of the soil profile.

Dynamic Aperture Measurements at the Advanced Light Source

International Nuclear Information System (INIS)

Decking, W.; Robin, D.

1999-01-01

A large dynamic aperture for a storage ring is of importance for long lifetimes and a high injection efficiency. Measurements of the dynamic aperture of the third generation synchrotron light source Advanced Light Source (ALS) using beam excitation with kicker magnets are presented. The experiments were done for various accelerator conditions, allowing us to investigate the influence of different working points, chromaticities, insertion devices, etc.. The results are compared both with tracking calculations and a simple model for the dynamic aperture yielding good agreements. This gives us confidence in the predictability of the nonlinear accelerator model. This is especially important for future ALS upgrades as well as new storage ring designs

Singer product apertures—A coded aperture system with a fast decoding algorithm

International Nuclear Information System (INIS)

Byard, Kevin; Shutler, Paul M.E.

2017-01-01

A new type of coded aperture configuration that enables fast decoding of the coded aperture shadowgram data is presented. Based on the products of incidence vectors generated from the Singer difference sets, we call these Singer product apertures. For a range of aperture dimensions, we compare experimentally the performance of three decoding methods: standard decoding, induction decoding and direct vector decoding. In all cases the induction and direct vector methods are several orders of magnitude faster than the standard method, with direct vector decoding being significantly faster than induction decoding. For apertures of the same dimensions the increase in speed offered by direct vector decoding over induction decoding is better for lower throughput apertures.

Singer product apertures—A coded aperture system with a fast decoding algorithm

Energy Technology Data Exchange (ETDEWEB)

Byard, Kevin, E-mail: kevin.byard@aut.ac.nz [School of Economics, Faculty of Business, Economics and Law, Auckland University of Technology, Auckland 1142 (New Zealand); Shutler, Paul M.E. [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore)

2017-06-01

A new type of coded aperture configuration that enables fast decoding of the coded aperture shadowgram data is presented. Based on the products of incidence vectors generated from the Singer difference sets, we call these Singer product apertures. For a range of aperture dimensions, we compare experimentally the performance of three decoding methods: standard decoding, induction decoding and direct vector decoding. In all cases the induction and direct vector methods are several orders of magnitude faster than the standard method, with direct vector decoding being significantly faster than induction decoding. For apertures of the same dimensions the increase in speed offered by direct vector decoding over induction decoding is better for lower throughput apertures.

Self characterization of a coded aperture array for neutron source imaging

Energy Technology Data Exchange (ETDEWEB)

Volegov, P. L., E-mail: volegov@lanl.gov; Danly, C. R.; Guler, N.; Merrill, F. E.; Wilde, C. H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Fittinghoff, D. N. [Livermore National Laboratory, Livermore, California 94550 (United States)

2014-12-15

The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning deuterium-tritium plasma during the stagnation stage of inertial confinement fusion implosions. Since the neutron source is small (∼100 μm) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-μm resolution are 20-cm long, triangular tapers machined in gold foils. These gold foils are stacked to form an array of 20 apertures for pinhole imaging and three apertures for penumbral imaging. These apertures must be precisely aligned to accurately place the field of view of each aperture at the design location, or the location of the field of view for each aperture must be measured. In this paper we present a new technique that has been developed for the measurement and characterization of the precise location of each aperture in the array. We present the detailed algorithms used for this characterization and the results of reconstructed sources from inertial confinement fusion implosion experiments at NIF.

Natural variation in stomatal response to closing stimuli among Arabidopsis thaliana accessions after exposure to lowe VPD as a tool to recognize the mechanism of disturbed stomatal functioning

NARCIS (Netherlands)

Ali Niaei Fard, S.; Meeteren, van U.

2014-01-01

Stomatal responses to closing stimuli are disturbed after long-term exposure of plants to low vapour pressure deficit (VPD). The mechanism behind this disturbance is not fully understood. Genetic variation between naturally occurring ecotypes can be helpful to elucidate the mechanism controlling

The chaotic dynamical aperture

International Nuclear Information System (INIS)

Lee, S.Y.; Tepikian, S.

1985-01-01

Nonlinear magnetic forces become more important for particles in the modern large accelerators. These nonlinear elements are introduced either intentionally to control beam dynamics or by uncontrollable random errors. Equations of motion in the nonlinear Hamiltonian are usually non-integrable. Because of the nonlinear part of the Hamiltonian, the tune diagram of accelerators is a jungle. Nonlinear magnet multipoles are important in keeping the accelerator operation point in the safe quarter of the hostile jungle of resonant tunes. Indeed, all the modern accelerator design have taken advantages of nonlinear mechanics. On the other hand, the effect of the uncontrollable random multipoles should be evaluated carefully. A powerful method of studying the effect of these nonlinear multipoles is using a particle tracking calculation, where a group of test particles are tracing through these magnetic multipoles in the accelerator hundreds to millions of turns in order to test the dynamical aperture of the machine. These methods are extremely useful in the design of a large accelerator such as SSC, LEP, HERA and RHIC. These calculations unfortunately take tremendous amount of computing time. In this paper, we try to apply the existing method in the nonlinear dynamics to study the possible alternative solution. When the Hamiltonian motion becomes chaotic, the tune of the machine becomes undefined. The aperture related to the chaotic orbit can be identified as chaotic dynamical aperture. We review the method of determining chaotic orbit and apply the method to nonlinear problems in accelerator physics. We then discuss the scaling properties and effect of random sextupoles

Variable aperture-based ptychographical iterative engine method

Science.gov (United States)

Sun, Aihui; Kong, Yan; Meng, Xin; He, Xiaoliang; Du, Ruijun; Jiang, Zhilong; Liu, Fei; Xue, Liang; Wang, Shouyu; Liu, Cheng

2018-02-01

A variable aperture-based ptychographical iterative engine (vaPIE) is demonstrated both numerically and experimentally to reconstruct the sample phase and amplitude rapidly. By adjusting the size of a tiny aperture under the illumination of a parallel light beam to change the illumination on the sample step by step and recording the corresponding diffraction patterns sequentially, both the sample phase and amplitude can be faithfully reconstructed with a modified ptychographical iterative engine (PIE) algorithm. Since many fewer diffraction patterns are required than in common PIE and the shape, the size, and the position of the aperture need not to be known exactly, this proposed vaPIE method remarkably reduces the data acquisition time and makes PIE less dependent on the mechanical accuracy of the translation stage; therefore, the proposed technique can be potentially applied for various scientific researches.

Performance limits of ion extraction systems with non-circular apertures

Energy Technology Data Exchange (ETDEWEB)

Shagayda, A., E-mail: shagayda@gmail.com; Madeev, S. [Keldysh Research Centre, Onezhskaya, 8, 125438 Moscow (Russian Federation)

2016-04-15

A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

Performance limits of ion extraction systems with non-circular apertures.

Science.gov (United States)

Shagayda, A; Madeev, S

2016-04-01

A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

Performance limits of ion extraction systems with non-circular apertures

Science.gov (United States)

Shagayda, A.; Madeev, S.

2016-04-01

A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

Performance limits of ion extraction systems with non-circular apertures

International Nuclear Information System (INIS)

Shagayda, A.; Madeev, S.

2016-01-01

A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

High-contrast visible nulling coronagraph for segmented and arbitrary telescope apertures

Science.gov (United States)

Hicks, Brian A.; Lyon, Richard G.; Bolcar, Matthew R.; Clampin, Mark; Petrone, Peter

2014-08-01

Exoplanet coronagraphy will be driven by the telescope architectures available and thus the system designer must have available one or more suitable coronagraphic instrument choices that spans the set of telescope apertures, including filled (off-axis), obscured (e.g. with secondary mirror spiders and struts), segmented apertures, such as JWST, and interferometric apertures. In this work we present one such choice of coronagraph, known as the visible nulling coronagraph (VNC), that spans all four types of aperture and also employs differential sensing and control.

Ships as salient objects in synthetic aperture radar imaginary

CSIR Research Space (South Africa)

Schwegmann, Colin P

2016-07-01

Full Text Available The widespread access to Synthetic Aperture Radar data has created a need for more precise ship extraction, specifically in low-to-medium resolution imagery. While Synthetic Aperture Radar pixel resolution is improving for a large swaths...

Electromagnetic Formation Flight (EMFF) for Sparse Aperture Arrays

Science.gov (United States)

Kwon, Daniel W.; Miller, David W.; Sedwick, Raymond J.

2004-01-01

Traditional methods of actuating spacecraft in sparse aperture arrays use propellant as a reaction mass. For formation flying systems, propellant becomes a critical consumable which can be quickly exhausted while maintaining relative orientation. Additional problems posed by propellant include optical contamination, plume impingement, thermal emission, and vibration excitation. For these missions where control of relative degrees of freedom is important, we consider using a system of electromagnets, in concert with reaction wheels, to replace the consumables. Electromagnetic Formation Flight sparse apertures, powered by solar energy, are designed differently from traditional propulsion systems, which are based on V. This paper investigates the design of sparse apertures both inside and outside the Earth's gravity field.

Exo-planet Direct Imaging with On-Axis and/or Segmented Apertures in Space: Adaptive Compensation of Aperture Discontinuities

Science.gov (United States)

Soummer, Remi

Capitalizing on a recent breakthrough in wavefront control theory for obscured apertures made by our group, we propose to demonstrate a method to achieve high contrast exoplanet imaging with on-axis obscured apertures. Our new algorithm, which we named Adaptive Compensation of Aperture Discontinuities (ACAD), provides the ability to compensate for aperture discontinuities (segment gaps and/or secondary mirror supports) by controlling deformable mirrors in a nonlinear wavefront control regime not utilized before but conceptually similar to the beam reshaping used in PIAA coronagraphy. We propose here an in-air demonstration at 1E- 7 contrast, enabled by adding a second deformable mirror to our current test-bed. This expansion of the scope of our current efforts in exoplanet imaging technologies will enabling us to demonstrate an integrated solution for wavefront control and starlight suppression on complex aperture geometries. It is directly applicable at scales from moderate-cost exoplanet probe missions to the 2.4 m AFTA telescopes to future flagship UVOIR observatories with apertures potentially 16-20 m. Searching for nearby habitable worlds with direct imaging is one of the top scientific priorities established by the Astro2010 Decadal Survey. Achieving this ambitious goal will require 1e-10 contrast on a telescope large enough to provide angular resolution and sensitivity to planets around a significant sample of nearby stars. Such a mission must of course also be realized at an achievable cost. Lightweight segmented mirror technology allows larger diameter optics to fit in any given launch vehicle as compared to monolithic mirrors, and lowers total life-cycle costs from construction through integration & test, making it a compelling option for future large space telescopes. At smaller scales, on-axis designs with secondary obscurations and supports are less challenging to fabricate and thus more affordable than the off-axis unobscured primary mirror designs

Drought limitations to leaf-level gas exchange: results from a model linking stomatal optimization and cohesion-tension theory

Science.gov (United States)

Kimberly A. Novick; Chelcy F. Miniat; James M. Vose

2016-01-01

We merge concepts from stomatal optimization theory and cohesion–tension theory to examine the dynamics of three mechanisms that are potentially limiting to leaf-level gas exchange in trees during drought: (1) a ‘demand limitation’ driven by an assumption of optimal stomatal functioning; (2) ‘hydraulic limitation’ of water movement from the roots to the leaves...

Redundancy of stomatal control for the circadian photosynthetic rhythm in Kalanchoë daigremontiana Hamet et Perrier.

Science.gov (United States)

Wyka, T P; Duarte, H M; Lüttge, U E

2005-03-01

In continuous light, the Crassulacean acid metabolism plant Kalanchoe daigremontiana Hamet et Perrier has a circadian rhythm of gas exchange with peaks occurring during the subjective night. The rhythm of gas exchange is coupled to a weak, reverse phased rhythm of quantum yield of photosystem II (Phi (PSII)). To test if the rhythm of Phi (PSII) persists in the absence of stomatal control, leaves were coated with a thin layer of translucent silicone grease which prevented CO2 and H2O exchange. In spite of this treatment, the rhythm of Phi (PSII) occurred with close to normal phase timing and with a much larger amplitude than in uncoated leaves. The mechanism underlying the Phi (PSII) rhythm in coated leaves can be explained by a circadian activity of phosphoenolpyruvate carboxylase (PEPC). At peaks of PEPC activity, the small amount of CO2 contained in the coated leaf could have become depleted, preventing the carboxylase activity of Rubisco and causing decreases in electron transport rates (observed as deep troughs of Phi (PSII) at 23-h in LL and at ca. 24-h intervals afterwards). Peaks of Phi (PSII) would be caused by a downregulation of PEPC leading to improved supply of CO2 to Rubisco. Substrate limitation of photochemistry at 23 h (trough of Phi (PSII)) was also suggested by the weak response of ETR in coated leaves to stepwise light enhancement. These results show that photosynthetic rhythmicity in K. daigremontiana is independent of stomatal regulation and may originate in the mesophyll.

Synthetic aperture radar capabilities in development

Energy Technology Data Exchange (ETDEWEB)

Miller, M. [Lawrence Livermore National Lab., CA (United States)

1994-11-15

The Imaging and Detection Program (IDP) within the Laser Program is currently developing an X-band Synthetic Aperture Radar (SAR) to support the Joint US/UK Radar Ocean Imaging Program. The radar system will be mounted in the program`s Airborne Experimental Test-Bed (AETB), where the initial mission is to image ocean surfaces and better understand the physics of low grazing angle backscatter. The Synthetic Aperture Radar presentation will discuss its overall functionality and a brief discussion on the AETB`s capabilities. Vital subsystems including radar, computer, navigation, antenna stabilization, and SAR focusing algorithms will be examined in more detail.

Aperture referral in dioptric systems with stigmatic elements

Directory of Open Access Journals (Sweden)

W. F. Harris

2012-12-01

Full Text Available A previous paper develops the general theory of aperture referral in linear optics and shows how several ostensibly distinct concepts, including the blur patch on the retina, the effective corneal patch, the projective field and the field of view, are now unified as particular applications of the general theory.  The theory allows for astigmatism and heterocentricity.  Symplecticity and the generality of the approach, however, make it difficult to gain insight and mean that the material is not accessible to readers unfamiliar with matrices and linear algebra. The purpose of this paper is to examine whatis, perhaps, the most important special case, that in which astigmatism is ignored.  Symplecticity and, hence, the mathematics become greatly simplified. The mathematics reduces largely to elementary vector algebra and, in some places, simple scalar algebra and yet retains the mathematical form of the general approach.  As a result the paper allows insight into and provides a stepping stone to the general theory.  Under referral an aperture under-goes simple scalar magnification and transverse translation.  The paper pays particular attention to referral to transverse planes in the neighbourhood of a focal point where the magnification may be positive, zero or negative.  Circular apertures are treated as special cases of elliptical apertures and the meaning of referred apertures of negative radius is explained briefly. (S Afr Optom 2012 71(1 3-11

Limited aperture effects on ultrasonic image reconstruction

International Nuclear Information System (INIS)

Kogan, V.G.; Rose, J.H.

1985-01-01

In the inverse Born approximation the shape of a weak scatterer can be determined from a knowledge of the backscattered ultrasonic amplitude for all directions of incidence and all frequencies. Two questions are considered. First, what information on the scatterer shape is preserved and what is degraded if the scattering data are available only within a limited set of incident directions (limited aperture). This problem is addressed for a spherical weakly scattering uniform flaw. It is shown that the problem of a general uniform ellipsoidal flaw can be reduced to the spherical case by a scale transformation; however, the apertures in these two cases must be related by the same transformation. Second, limited aperture and finite bandwidth Born inversions were performed for strongly scattering flaws (voids and cracks) using numerically generated scattering amplitudes. These inversions were then compared with the weak scattering analytic results, which show many common features

Variable aperture-based ptychographical iterative engine method.

Science.gov (United States)

Sun, Aihui; Kong, Yan; Meng, Xin; He, Xiaoliang; Du, Ruijun; Jiang, Zhilong; Liu, Fei; Xue, Liang; Wang, Shouyu; Liu, Cheng

2018-02-01

A variable aperture-based ptychographical iterative engine (vaPIE) is demonstrated both numerically and experimentally to reconstruct the sample phase and amplitude rapidly. By adjusting the size of a tiny aperture under the illumination of a parallel light beam to change the illumination on the sample step by step and recording the corresponding diffraction patterns sequentially, both the sample phase and amplitude can be faithfully reconstructed with a modified ptychographical iterative engine (PIE) algorithm. Since many fewer diffraction patterns are required than in common PIE and the shape, the size, and the position of the aperture need not to be known exactly, this proposed vaPIE method remarkably reduces the data acquisition time and makes PIE less dependent on the mechanical accuracy of the translation stage; therefore, the proposed technique can be potentially applied for various scientific researches. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Synthetic aperture tissue and flow ultrasound imaging

DEFF Research Database (Denmark)

Nikolov, Svetoslav

imaging applied to medical ultrasound. It is divided into two major parts: tissue and blood flow imaging. Tissue imaging using synthetic aperture algorithms has been investigated for about two decades, but has not been implemented in medical scanners yet. Among the other reasons, the conventional scanning...... and beamformation methods are adequate for the imaging modalities in clinical use - the B-mode imaging of tissue structures, and the color mapping of blood flow. The acquisition time, however, is too long, and these methods fail to perform real-time three-dimensional scans. The synthetic transmit aperture......, on the other hand, can create a Bmode image with as little as 2 emissions, thus significantly speeding-up the scan procedure. The first part of the dissertation describes the synthetic aperture tissue imaging. It starts with an overview of the efforts previously made by other research groups. A classification...

Effect of Light Quality on Stomatal Opening in Leaves of Xanthium strumarium L. 1

Science.gov (United States)

Sharkey, Thomas D.; Raschke, Klaus

1981-01-01

Flux response curves were determined at 16 wavelengths of light for the conductance for water vapor of the lower epidermis of detached leaves of Xanthium strumarium L. An action spectrum of stomatal opening resulted in which blue light (wavelengths between 430 and 460 nanometers) was nearly ten times more effective than red light (wavelengths between 630 and 680 nanometers) in producing a conductance of 15 centimoles per square meter per second. Stomata responded only slightly to green light. An action spectrum of stomatal responses to red light corresponded to that of CO2 assimilation; the inhibitors of photosynthetic electron transport, cyanazine (2-chloro-4[1-cyano-1-methylethylamino]-6-ethylamino-s-triazine) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea, eliminated the response to red light. This indicates that light absorption by chlorophyll is the cause of stomatal sensitivity to red light. Determination of flux response curves on leaves in the normal position (upper epidermis facing the light) or in the inverted position (lower epidermis facing the light) led to the conclusion that the photoreceptors for blue as well as for red light are located on or near the surfaces of the leaves; presumably they are in the guard cells themselves. PMID:16662069

Identifying the tundra-forest border in the stomate record: an analysis of lake surface samples from the Yellowknife area, Northwest Territories, Canada

Energy Technology Data Exchange (ETDEWEB)

Hansen, B.C.S. [Minnesota Univ., Minneapolis, MN (United States). Limnological Research Center; MacDonald, G.M. [California Univ., Los Angeles, CA (United States). Dept. of Botanical Sciences; Moser, K.A. [McMaster Univ., Hamilton, ON (Canada)

1996-05-01

The relationship between conifer stomata and existing vegetation across tundra, forest-tundra, and closed zones in the Yellowknife area of the Northwest Territories was studied. Conifer stomata were identified in surface samples from lakes in the treeline zone, but were absent in samples from tundra lakes. Stomate analysis was recorded and the results were presented in a concentration diagram plotting stomate concentrations according to vegetation zone. Conifer stomate analysis was not able to resolve differences between forest-tundra and closed forest. Nevertheless, it was suggested that stomate analysis will become an important technique supplementing pollen analysis for reconstructing past tree-line changes since the presence of stomata in lakes make it possible to separate the tundra from forest-tundra and closed forest. The limited dispersal of conifer stomata permitted a better resolution of tree-line boundaries than did pollen. 13 refs., 3 figs.

Autofocus algorithm for synthetic aperture radar imaging with large curvilinear apertures

Science.gov (United States)

Bleszynski, E.; Bleszynski, M.; Jaroszewicz, T.

2013-05-01

An approach to autofocusing for large curved synthetic aperture radar (SAR) apertures is presented. Its essential feature is that phase corrections are being extracted not directly from SAR images, but rather from reconstructed SAR phase-history data representing windowed patches of the scene, of sizes sufficiently small to allow the linearization of the forward- and back-projection formulae. The algorithm processes data associated with each patch independently and in two steps. The first step employs a phase-gradient-type method in which phase correction compensating (possibly rapid) trajectory perturbations are estimated from the reconstructed phase history for the dominant scattering point on the patch. The second step uses phase-gradient-corrected data and extracts the absolute phase value, removing in this way phase ambiguities and reducing possible imperfections of the first stage, and providing the distances between the sensor and the scattering point with accuracy comparable to the wavelength. The features of the proposed autofocusing method are illustrated in its applications to intentionally corrupted small-scene 2006 Gotcha data. The examples include the extraction of absolute phases (ranges) for selected prominent point targets. They are then used to focus the scene and determine relative target-target distances.

Statistical measurement of power spectrum density of large aperture optical component

International Nuclear Information System (INIS)

Xu Jiancheng; Xu Qiao; Chai Liqun

2010-01-01

According to the requirement of ICF, a method based on statistical theory has been proposed to measure the power spectrum density (PSD) of large aperture optical components. The method breaks the large-aperture wavefront into small regions, and obtains the PSD of the large-aperture wavefront by weighted averaging of the PSDs of the regions, where the weight factor is each region's area. Simulation and experiment demonstrate the effectiveness of the proposed method. They also show that, the obtained PSDs of the large-aperture wavefront by statistical method and sub-aperture stitching method fit well, when the number of small regions is no less than 8 x 8. The statistical method is not sensitive to translation stage's errors and environment instabilities, thus it is appropriate for PSD measurement during the process of optical fabrication. (authors)

Investigation of the effect of the rebamipide mouthwash on the crisis of the stomatitis induced by the cancer chemotherapy and/or radiotherapy

International Nuclear Information System (INIS)

Kawata, Keishi; Hanawa, Takehisa; Hanawa, Kazumi

2001-01-01

Stomatitis is well-known as one of the undesirable side effects induced by high and/or multiple dosing of cytotoxic drugs such as 5-fluorouracil (5-FU). Stomatitis causes pain in the oral cavity, impaired swallowing or loss of appetite, and finally, lowering of the quality of life (QOL) of patients. In this study, we attempted to apply a new mouthwash containing rebamipide (REB) which is known as the anti-activated oxygen agent. Rebamipide mouthwash (REB-M) showed the effectiveness to the crisis of the stomatitis during the cancer chemotherapy and/or radiotherapy. (author)

Nitric Oxide (NO) Measurements in Stomatal Guard Cells.

Science.gov (United States)

Agurla, Srinivas; Gayatri, Gunja; Raghavendra, Agepati S

2016-01-01

The quantitative measurement of nitric oxide (NO) in plant cells acquired great importance, in view of the multifaceted function and involvement of NO as a signal in various plant processes. Monitoring of NO in guard cells is quite simple because of the large size of guard cells and ease of observing the detached epidermis under microscope. Stomatal guard cells therefore provide an excellent model system to study the components of signal transduction. The levels and functions of NO in relation to stomatal closure can be monitored, with the help of an inverted fluorescence or confocal microscope. We can measure the NO in guard cells by using flouroprobes like 4,5-diamino fluorescein diacetate (DAF-2DA). This fluorescent dye, DAF-2DA, is cell permeable and after entry into the cell, the diacetate group is removed by the cellular esterases. The resulting DAF-2 form is membrane impermeable and reacts with NO to generate the highly fluorescent triazole (DAF-2T), with excitation and emission wavelengths of 488 and 530 nm, respectively. If time-course measurements are needed, the epidermis can be adhered to a cover-glass or glass slide and left in a small petri dishes. Fluorescence can then be monitored at required time intervals; with a precaution that excitation is done minimally, only when a fluorescent image is acquired. The present method description is for the epidermis of Arabidopsis thaliana and Pisum sativum and should work with most of the other dicotyledonous plants.

Parameter Optimization of Multi-Element Synthetic Aperture Imaging Systems

Directory of Open Access Journals (Sweden)

Vera Behar

2007-03-01

Full Text Available In conventional ultrasound imaging systems with phased arrays, the further improvement of lateral resolution requires enlarging of the number of array elements that in turn increases both, the complexity and the cost, of imaging systems. Multi-element synthetic aperture focusing (MSAF systems are a very good alternative to conventional systems with phased arrays. The benefit of the synthetic aperture is in reduction of the system complexity, cost and acquisition time. In a MSAF system considered in the paper, a group of elements transmit and receive signals simultaneously, and the transmit beam is defocused to emulate a single element response. The echo received at each element of a receive sub-aperture is recorded in the computer memory. The process of transmission/reception is repeated for all positions of a transmit sub-aperture. All the data recordings associated with each corresponding pair "transmit-receive sub-aperture" are then focused synthetically producing a low-resolution image. The final high-resolution image is formed by summing of the all low-resolution images associated with transmit/receive sub-apertures. A problem of parameter optimization of a MSAF system is considered in this paper. The quality of imaging (lateral resolution and contrast is expressed in terms of the beam characteristics - beam width and side lobe level. The comparison between the MSAF system described in the paper and an equivalent conventional phased array system shows that the MSAF system acquires images of equivalent quality much faster using only a small part of the power per image.

Determination of the paraxial focal length using Zernike polynomials over different apertures

Science.gov (United States)

Binkele, Tobias; Hilbig, David; Henning, Thomas; Fleischmann, Friedrich

2017-02-01

The paraxial focal length is still the most important parameter in the design of a lens. As presented at the SPIE Optics + Photonics 2016, the measured focal length is a function of the aperture. The paraxial focal length can be found when the aperture approaches zero. In this work, we investigate the dependency of the Zernike polynomials on the aperture size with respect to 3D space. By this, conventional wavefront measurement systems that apply Zernike polynomial fitting (e.g. Shack-Hartmann-Sensor) can be used to determine the paraxial focal length, too. Since the Zernike polynomials are orthogonal over a unit circle, the aperture used in the measurement has to be normalized. By shrinking the aperture and keeping up with the normalization, the Zernike coefficients change. The relation between these changes and the paraxial focal length are investigated. The dependency of the focal length on the aperture size is derived analytically and evaluated by simulation and measurement of a strong focusing lens. The measurements are performed using experimental ray tracing and a Shack-Hartmann-Sensor. Using experimental ray tracing for the measurements, the aperture can be chosen easily. Regarding the measurements with the Shack-Hartmann- Sensor, the aperture size is fixed. Thus, the Zernike polynomials have to be adapted to use different aperture sizes by the proposed method. By doing this, the paraxial focal length can be determined from the measurements in both cases.

Permeability and dispersivity of variable-aperture fracture systems

International Nuclear Information System (INIS)

Tsang, Y.W.; Tsang, C.F.

1990-01-01

A number of recent experiments have pointed out the need of including the effects of aperture variation within each fracture in predicting flow and transport properties of fractured media. This paper introduces a new approach in which medium properties, such as the permeability to flow and dispersivity in tracer transport, are correlated to only three statistical parameters describing the fracture aperture probability distribution and the aperture spatial correlation. We demonstrate how saturated permeability and relative permeabilities for flow, as well as dispersion for solute transport in fractures may be calculated. We are in the process of examining the applicability of these concepts to field problems. Results from the evaluation and analysis of the recent Stripa-3D field data are presented. 13 refs., 10 figs

Highly uniform parallel microfabrication using a large numerical aperture system

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zi-Yu; Su, Ya-Hui, E-mail: ustcsyh@ahu.edu.cn, E-mail: dongwu@ustc.edu.cn [School of Electrical Engineering and Automation, Anhui University, Hefei 230601 (China); Zhang, Chen-Chu; Hu, Yan-Lei; Wang, Chao-Wei; Li, Jia-Wen; Chu, Jia-Ru; Wu, Dong, E-mail: ustcsyh@ahu.edu.cn, E-mail: dongwu@ustc.edu.cn [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026 (China)

2016-07-11

In this letter, we report an improved algorithm to produce accurate phase patterns for generating highly uniform diffraction-limited multifocal arrays in a large numerical aperture objective system. It is shown that based on the original diffraction integral, the uniformity of the diffraction-limited focal arrays can be improved from ∼75% to >97%, owing to the critical consideration of the aperture function and apodization effect associated with a large numerical aperture objective. The experimental results, e.g., 3 × 3 arrays of square and triangle, seven microlens arrays with high uniformity, further verify the advantage of the improved algorithm. This algorithm enables the laser parallel processing technology to realize uniform microstructures and functional devices in the microfabrication system with a large numerical aperture objective.

Stomatal and pavement cell density linked to leaf internal CO2 concentration

Czech Academy of Sciences Publication Activity Database

Šantrůček, Jiří; Vráblová, M.; Šimková, Marie; Hronková, Marie; Drtinová, M.; Květoň, J.; Vrábl, D.; Kubásek, J.; Macková, J.; Wiesnerová, Dana; Neuwithová, J.; Schreiber, L.

2014-01-01

Roč. 114, č. 2 (2014), s. 191-202 ISSN 0305-7364 R&D Projects: GA ČR(CZ) GAP501/12/1261 Institutional support: RVO:60077344 Keywords : Stomatal density * Stomata development * Pavement cells Subject RIV: CE - Biochemistry Impact factor: 3.654, year: 2014

Electromagnetic field scattering by a triangular aperture.

Science.gov (United States)

Harrison, R E; Hyman, E

1979-03-15

The multiple Laplace transform has been applied to analysis and computation of scattering by a double triangular aperture. Results are obtained which match far-field intensity distributions observed in experiments. Arbitrary polarization components, as well as in-phase and quadrature-phase components, may be determined, in the transform domain, as a continuous function of distance from near to far-field for any orientation, aperture, and transformable waveform. Numerical results are obtained by application of numerical multiple inversions of the fully transformed solution.

Biomineral repair of abalone shell apertures.

Science.gov (United States)

Cusack, Maggie; Guo, Dujiao; Chung, Peter; Kamenos, Nicholas A

2013-08-01

The shell of the gastropod mollusc, abalone, is comprised of nacre with an outer prismatic layer that is composed of either calcite or aragonite or both, depending on the species. A striking characteristic of the abalone shell is the row of apertures along the dorsal margin. As the organism and shell grow, new apertures are formed and the preceding ones are filled in. Detailed investigations, using electron backscatter diffraction, of the infill in three species of abalone: Haliotis asinina, Haliotis gigantea and Haliotis rufescens reveals that, like the shell, the infill is composed mainly of nacre with an outer prismatic layer. The infill prismatic layer has identical mineralogy as the original shell prismatic layer. In H. asinina and H. gigantea, the prismatic layer of the shell and infill are made of aragonite while in H. rufescens both are composed of calcite. Abalone builds the infill material with the same high level of biological control, replicating the structure, mineralogy and crystallographic orientation as for the shell. The infill of abalone apertures presents us with insight into what is, effectively, shell repair. Copyright © 2013 Elsevier Inc. All rights reserved.

Adjustable liquid aperture to eliminate undesirable light in holographic projection.

Science.gov (United States)

Wang, Di; Liu, Chao; Li, Lei; Zhou, Xin; Wang, Qiong-Hua

2016-02-08

In this paper, we propose an adjustable liquid aperture to eliminate the undesirable light in a holographic projection. The aperture is based on hydrodynamic actuation. A chamber is formed with a cylindrical tube. A black droplet is filled in the sidewall of the cylinder tube and the outside space is the transparent oil which is immiscible with the black droplet. An ultrathin glass sheet is attached on the bottom substrate of the device and a black shading film is secured to the central area of the glass sheet. By changing the volume of the black droplet, the black droplet will move to the middle or sidewall due to hydrodynamic actuation, so the device can be used as an adjustable aperture. A divergent spherical wave and a solid lens are used to separate the focus planes of the reconstructed image and diffraction beams induced by the liquid crystal on silicon in the holographic projection. Then the aperture is used to eliminate the diffraction beams by adjusting the size of the liquid aperture and the holographic projection does not have undesirable light.

Focusing optical waves with a rotationally symmetric sharp-edge aperture

Science.gov (United States)

Hu, Yanwen; Fu, Shenhe; Li, Zhen; Yin, Hao; Zhou, Jianying; Chen, Zhenqiang

2018-04-01

While there has been various kinds of patterned structures proposed for wave focusing, these patterned structures usually involve complicated lithographic techniques since the element size of the patterned structures should be precisely controlled in microscale or even nanoscale. Here we propose a new and straightforward method for focusing an optical plane wave in free space with a rotationally symmetric sharp-edge aperture. The focusing phenomenon of wave is realized by superposition of a portion of the higher-order symmetric plane waves generated from the sharp edges of the apertures, in contrast to previously focusing techniques which usually depend on a curved phase. We demonstrate both experimentally and theoretically the focusing effect with a series of apertures having different rotational symmetry, and find that the intensity of the hotspots could be controlled by the symmetric strength of the sharp-edge apertures. The presented results would advance the conventional wisdom that light would diffract in all directions and become expanding when it propagates through an aperture. The proposed method is easy to be processed, and might open potential applications in interferometry, image, and superresolution.

Estimating Latest Cretaceous and Tertiary Atmospheric PCO2 from Stomatal Indices

Science.gov (United States)

Royer, D. L.; Wing, S. L.; Beerling, D. J.

2001-05-01

Most modern C3 seed plants show an inverse relationship between PCO2 and stomatal index (SI), where SI is the proportion of epidermal cells that are stomatal packages. This plant-atmosphere response therefore provides a reliable approach for estimating paleo-CO2 levels. Since stomatal responses to CO2 are generally species-specific, one is limited in paleo-reconstructions to species that exist both in the fossil record and living today. Fossils morphologically similar to living Ginkgo biloba and Metasequoia glyptostroboides extend back to the early and late Cretaceous, respectively, indicating that the fossil and living forms are very closely related. Measurements of SI made on fossil Ginkgo and Metasequoia were calibrated with historical collections of G. biloba and M. glyptostroboides leaves from sites that developed during the anthropogenically-driven CO2 increases of the past 145 years (288-369 ppmv) and with saplings of G. biloba and M. glyptostroboides grown in CO2 controlled growth chambers (350-800 ppmv). Both nonlinear regressions are highly significant (Ginkgo: n = 40, r2 = 0.91; Metasequoia: n = 18; r2 = 0.85). Results from a sequence of 23 latest Cretaceous to early Eocene-aged Ginkgo-bearing sites indicate that CO2 remained between 300 and 450 ppmv with the exception of one high estimate ( ~800 ppmv) near the Paleocene/Eocene boundary, and results from 4 middle Miocene-aged Ginkgo- and Metasequoia-bearing sites indicate that CO2 was between 320 and 400 ppmv. If correct, the CO2 values estimated here are too low to explain via the CO2 greenhouse effect alone the higher global mean temperatures (e.g., 3-4 ° C for the early Eocene) inferred from models and geological data for these two intervals.

Maximum nondiffracting propagation distance of aperture-truncated Airy beams

Science.gov (United States)

Chu, Xingchun; Zhao, Shanghong; Fang, Yingwu

2018-05-01

Airy beams have called attention of many researchers due to their non-diffracting, self-healing and transverse accelerating properties. A key issue in research of Airy beams and its applications is how to evaluate their nondiffracting propagation distance. In this paper, the critical transverse extent of physically realizable Airy beams is analyzed under the local spatial frequency methodology. The maximum nondiffracting propagation distance of aperture-truncated Airy beams is formulated and analyzed based on their local spatial frequency. The validity of the formula is verified by comparing the maximum nondiffracting propagation distance of an aperture-truncated ideal Airy beam, aperture-truncated exponentially decaying Airy beam and exponentially decaying Airy beam. Results show that the formula can be used to evaluate accurately the maximum nondiffracting propagation distance of an aperture-truncated ideal Airy beam. Therefore, it can guide us to select appropriate parameters to generate Airy beams with long nondiffracting propagation distance that have potential application in the fields of laser weapons or optical communications.

Aperture and optics–measurements and conclusions

CERN Document Server

Redaelli, S; Bruce, R; Buffat, X; Giovannozzi, M; Lamont, M; Miyamoto, R; Müller, G; Tomás, R; Vanbavinckhove, G; Wenninger, J

2012-01-01

In 2011, the LHC has delivered collisions with different optics configurations in the four interaction points, at an operating energy of 3.5 TeV. The performance has been pushed during the year until a final configuration with 3 IPs squeezed to 1 m was achieved. Correspondingly, the machine aperture has been measured in the different configurations at injection and at top energy, to ensure a safe operation in all conditions of $\\beta^*$ and crossing angle configuration. In this paper, the 2011 commissioning experience of LHC optics is reviewed and the results of aperture measurements are presented. Measurement requirements for 2012 and possible improvements are also discussed.

Enhanced transmission of transverse electric waves through periodic arrays of structured subwavelength apertures

DEFF Research Database (Denmark)

Xiao, Sanshui; Peng, Liang; Mortensen, Asger

2010-01-01

Transmission through sub-wavelength apertures in perfect metals is expected to be strongly suppressed. However, by structural engineering of the apertures, we numerically demonstrate that the transmission of transverse electric waves through periodic arrays of subwavelength apertures in a thin...... metallic film can be significantly enhanced. Based on equivalent circuit theory analysis, periodic arrays of square structured subwavelength apertures are obtained with a 1900-fold transmission enhancement factor when the side length a of the apertures is 10 times smaller than the wavelength (a/λ =0...

Nutritional responses to soil drying and rewetting cycles under partial root-zone drying irrigation

DEFF Research Database (Denmark)

Wang, Yaosheng; Jensen, Christian Richardt; Liu, Fulai

2017-01-01

signaling that regulates stomatal aperture. PRI induced soil DRW cycles and more soil water dynamics in the root zone enhance soil nutrient mineralization process and thus increase the bioavailability of soil nutrients, resulting in improved nitrogen (N) and phosphorus (P) uptake, in which soil microbial...... processes play a key role. Studies investigating how soil DRW cycles and water dynamics under PRI on nutrient transport in soil solution, soil microbe mediated P transformation, interactions between phytohormones and nutrient uptake, root morphological and architectural traits for nutrient acquisition......Abstract Repeated soil drying and rewetting (DRW) cycles occur in rainfed and irrigated agriculture. The intensity and frequency of DRW cycles regulate both microbial physiology and soil physical processes, hereby affecting the mineralization and immobilization of soil nutrients...

Recalibrating the Ginkgo Stomatal Index Proxy for Past CO2 with Herbarium Specimens

Science.gov (United States)

Conde, G. D.; Retallack, G.

2015-12-01

The stomatal index of plant cuticles is inversely related to atmospheric CO2 concentrations, as calibrated from greenhouse experiments and herbarium specimens. Such calibration data for Ginkgo biloba are available for the ongoing rise in atmospheric CO2 and for high levels of CO2 anticipated in the future, but lacking for low CO2 levels of preindustrial and glacial ages. The oldest modern specimen that we have been able to obtain consists of leaf fragments collected in 1829 and provided by Arne Anderberg from the Swedish Natural History Museum. The specimen was labeled "Argentina", but also "Hortus Botanicus Augustinus", a garden founded in 1638 in Amsterdam, Netherlands. Ginkgo has a very thin cuticle that is difficult to prepare, but images very similar to cuticular preparation can be obtained by backscatter SEM imagery. We also obtained secondary SEM images of the same areas and counted 13 images with 6,184 cells from five leaf fragments. Our analyses yield a stomatal index of 10.9 ± 0.9 % for an atmospheric CO2 of 286 ppm, as determined by ice core data from Ciais and Sabine for IPCC-2013. This value is lower than from previous calibration curves for this level of CO2 and changes their curvature. With additional late nineteenth, twentieth and twenty-first century leaves, we can improve both the precision and lower limits of the transfer function for atmospheric CO2 from Ginkgo stomatal index last revised in 2009.

Fast decoding algorithms for coded aperture systems

International Nuclear Information System (INIS)

Byard, Kevin

2014-01-01

Fast decoding algorithms are described for a number of established coded aperture systems. The fast decoding algorithms for all these systems offer significant reductions in the number of calculations required when reconstructing images formed by a coded aperture system and hence require less computation time to produce the images. The algorithms may therefore be of use in applications that require fast image reconstruction, such as near real-time nuclear medicine and location of hazardous radioactive spillage. Experimental tests confirm the efficacy of the fast decoding techniques

Scale-dependent Patterns in One-dimensional Fracture Spacing and Aperture Data

Science.gov (United States)

Roy, A.; Perfect, E.

2013-12-01

One-dimensional scanline data about fracture spacing and size attributes such as aperture or length are mostly considered in separate studies that compute the cumulative frequency of these attributes without regard to their actual spatial sequence. In a previous study, we showed that spacing data can be analyzed using lacunarity to identify whether fractures occur in clusters. However, to determine if such clusters also contain the largest fractures in terms of a size attribute such as aperture, it is imperative that data about the size attribute be integrated with information about fracture spacing. While for example, some researchers have considered aperture in conjunction with spacing, their analyses were either applicable only to a specific type of data (e.g. multifractal) or failed to characterize the data at different scales. Lacunarity is a technique for analyzing multi-scale non-binary data and is ideally-suited for characterizing scanline data with spacing and aperture values. We present a technique that can statistically delineate the relationship between size attributes and spatial clustering. We begin by building a model scanline that has complete partitioning of fractures with small and large apertures between the intercluster regions and clusters. We demonstrate that the ratio of lacunarity for this model to that of its counterpart for a completely randomized sequence of apertures can be used to determine whether large-aperture fractures preferentially occur next to each other. The technique is then applied to two natural fracture scanline datasets, one with most of the large apertures occurring in fracture clusters, and the other with more randomly-spaced fractures, without any specific ordering of aperture values. The lacunarity ratio clearly discriminates between these two datasets and, in the case of the first example, it is also able to identify the range of scales over which the widest fractures are clustered. The technique thus developed for

Dynamic aperture and transverse proton diffusion in HERA

International Nuclear Information System (INIS)

Zimmermann, F.

1994-04-01

The dynamic aperture caused by persistent-current nonlinear field errors is an important concern in the design of superconducting hadron storage rings. The HERA proton ring is the second superconducting accelerator in operation. In this lecture note, its measured dynamic aperture is compared with that inferred from comprehensive trackig studies. To understand the difference between prediction and measurement, a semi-analytical method is developed for evaluating transverse diffusion rates due to various processes, such as modulational diffusion or sweeping diffusion this analysis makes use of parameters for high-order resonances in the transverse phase space, which are obtained by normal-form algorithms using differential-algebra software. This semi-analytical results are consistent wit the measurements, and suggest that the actual dynamic aperture is caused by an interplay of tune modulation and nonlinear magnetic fields

Inter and intra-specific variation in photosynthetic acclimation response to long term exposure of elevated carbon dioxide

Energy Technology Data Exchange (ETDEWEB)

Wilkinson, M. [Univ. of Essex, Colchester (United Kingdom)]|[Writtle Coll. (United Kingdom)

1996-08-01

The response of intra and interspecific variation in photosynthetic acclimation to growth at elevated atmospheric CO{sub 2} concentration (600{micro}mol mol-l) in six important grassland species was investigated. Plants were grown in a background sward of Lolium perenne and measurements were made after four years of growth at elevated C{sub a}. Elevated CO{sub 2} was maintained using a FACE (Free-Air Carbon Enrichment) system. Significant intra and interspecific variation in acclimation response was demonstrated. The response of adaxial and abaxial stomatal conductance to elevated CO{sub 2} was also investigated. The stomatal conductance of both the adaxial and abaxial leaf surfaces was found to be reduced by elevated C{sub a}. Significant asymmetric responses in stomatal conductance was demonstrated in D. glomerata and T. pratense. Analysis of stomatal indices and densities indicated that the observed reductions in stomatal conductance were probably the result of changes in stomatal aperture.

Internal coordination between hydraulics and stomatal control in leaves.

Science.gov (United States)

Brodribb, Tim J; Jordan, Gregory J

2008-11-01

The stomatal response to changing leaf-atmospheric vapour pressure gradient (D(l)) is a crucial yet enigmatic process that defines the daily course of leaf gas exchange. Changes in the hydration of epidermal cells are thought to drive this response, mediated by the transpiration rate and hydraulic conductance of the leaf. Here, we examine whether species-specific variation in the sensitivity of leaves to perturbation of D(l) is related to the efficiency of water transport in the leaf (leaf hydraulic conductivity, K(leaf)). We found good correlation between maximum liquid (K(leaf)) and gas phase conductances (g(max)) in leaves, but there was no direct correlation between normalized D(l) sensitivity and K(leaf). The impact of K(leaf) on D(l) sensitivity in our diverse sample of eight species was important only after accounting for the strong relationship between K(leaf) and g(max). Thus, the ratio of g(max)/K(leaf) was strongly correlated with stomatal sensitivity to D(l). This ratio is an index of the degree of hydraulic buffering of the stomata against changes in D(l), and species with high g(max) relative to K(leaf) were the most sensitive to D(l) perturbation. Despite the potentially high adaptive significance of this phenomenon, we found no significant phylogenetic or ecological trend in our species.

Spaceborne L-band Radiometers: Push-broom or Synthetic Aperture?

DEFF Research Database (Denmark)

Skou, Niels

2004-01-01

L-band radiometers can measure ocean salinity and soil moisture from space. A synthetic aperture radiometer system, SMOS, is under development by ESA for launch in 2007. A real aperture push-broom system, Aquarius, has been approved by NASA for launch in 2008. Pros et cons of the two fundamentally...

DESIGN OF MULTILAYER APERTURE COUPLED STACKED MICROSTRIP PATCH ANTENNA FOR WLAN APPLICATIONS

Directory of Open Access Journals (Sweden)

P. Jothilakshmi

2015-10-01

Full Text Available One of the major drawbacks of microstrip patch antenna is its narrow bandwidth. The solution of this problem is to use aperture coupled stacked micro strip patch antenna. The antenna uses a combination of aperture coupled feeding technique and multi- layer radiating patch in order for the radiating elements are increase the gain bandwidth. The ‘I’ and ‘H’ shaped aperture slots are etched onto the ground plane. It is used to transfer the energy from feed line to stacked patch. A variation of the feed line length controls the selected aperture slots to be active. The waves from the selected activated aperture slots will radiate to particular radiating patch and achieve the desired resonant frequency. The air gap is used to avoid coupling loss between the aperture slots and stacked patches. The observed simulated and measured results show that the proposed antenna structure resonated at 2.51 GHz frequency with reduced return loss and optimum voltage standing wave ratio.

MD1405: Demonstration of forced dynamic aperture measurements at injection

CERN Document Server

Carlier, Felix Simon; Persson, Tobias Hakan Bjorn; Tomas Garcia, Rogelio; CERN. Geneva. ATS Department

2017-01-01

Accurate measurements of dynamic aperture become more important for the LHC as it advances into increasingly nonlinear regimes of operations, as well as for the High Luminosity LHC where machine nonlinearities will have a significantly larger impact. Direct dynamic aperture measurements at top energy in the LHC are challenging, and conventional single kick methods are not viable. Dynamic aperture measurements under forced oscillation of AC dipoles have been proposed as s possible alternative observable. A first demonstration of forced DA measurements at injections energy is presented.

Apodised aperture using rotation of plane of polarization

International Nuclear Information System (INIS)

Simmons, W.W.; Leppelmeier, G.W.; Johnson, B.C.

1975-01-01

An apodised aperture based on the rotation of plane of polarization producing desirable characteristics on a transmitted light beam such as beam profiling in high flux laser amplifier chains is described. The apodised aperture is made with a lossless element by using one or more polarizers and/or analyzers and magneto-optical Faraday means for selectively rotating the plane of polarized radiation over the cross section to effect the desired apodisation

Modern pollen and stomate deposition in lake surface sediments from across the treeline on the Kola Peninsula, Russia.

Science.gov (United States)

Gervais, B R.; MacDonald, G M.

2001-04-01

We sampled and analyzed surface sediments from 31 lakes along a latitudinal transect crossing the coniferous treeline on the Kola Peninsula, Russia. The major vegetation zones along the transect were tundra, birch-forest tundra, pine-forest tundra, and forest. The results indicate that the major vegetation types in our study area have distinct pollen spectra. Sum-of-squares cluster analysis and principal components analysis (PCA) groupings of pollen sites correspond to the major vegetation zones. PCA ordination of taxa indicates that the first axis separates taxa typical of the forest zone (Pinus, Picea) from taxa typical of tundra and forest-tundra zones (Polypodiaceae, Ericaceae, and Betula). The current position of the coniferous treeline, defined in our region by Pinus sylvestris, occurs roughly where Pinus pollen values reach 35% or greater. Arboreal pollen (AP)/non-arboreal pollen (NAP) ratios were calculated for each site and plotted against geographic distance along the transect. AP/NAP ratios of 7 or greater are found within pine-forest tundra and forest vegetation zones. Pinus stomates (dispersed stomatal guard cells) are absent from sites north of the coniferous treeline and all but two samples from the forested sites contain stomates. Stomate concentrations among the samples are highly variable and range from 10 to 458 per ml and positively correlate with the changing Pinus pollen values.

Updated stomatal flux and flux-effect models for wheat for quantifying effects of ozone on grain yield, grain mass and protein yield.

Science.gov (United States)

Grünhage, Ludger; Pleijel, Håkan; Mills, Gina; Bender, Jürgen; Danielsson, Helena; Lehmann, Yvonne; Castell, Jean-Francois; Bethenod, Olivier

2012-06-01

Field measurements and open-top chamber experiments using nine current European winter wheat cultivars provided a data set that was used to revise and improve the parameterisation of a stomatal conductance model for wheat, including a revised value for maximum stomatal conductance and new functions for phenology and soil moisture. For the calculation of stomatal conductance for ozone a diffusivity ratio between O(3) and H(2)O in air of 0.663 was applied, based on a critical review of the literature. By applying the improved parameterisation for stomatal conductance, new flux-effect relationships for grain yield, grain mass and protein yield were developed for use in ozone risk assessments including effects on food security. An example of application of the flux model at the local scale in Germany shows that negative effects of ozone on wheat grain yield were likely each year and on protein yield in most years since the mid 1980s. Copyright © 2012 Elsevier Ltd. All rights reserved.

11 T Twin-Aperture Nb$_3$Sn Dipole Development for LHC Upgrades

CERN Document Server

Zlobin, A V; Apollinari, G; Auchmann, B; Barzi, E; Izquierdo Bermudez, S; Bossert, R; Buehler, M; Chlachidze, G; DiMarco, J; Karppinen, M; Nobrega, F; Novitski, I; Rossi, L; Smekens, D; Tartaglia, M; Turrioni, D; Velev, Genadi

2015-01-01

FNAL and CERN are developing a twin-aperture 11 T Nb$_{3}$Sn dipole suitable for installation in the LHC. This paper describes the design and parameters of the 11 T dipole developed at FNAL for the LHC upgrades in both single-aperture and twin-aperture configurations, and presents details of the constructed dipole models. Results of studies of magnet quench performance, quench protection and magnetic measurements performed using short 1 m long coils in the dipole mirror and single-aperture configurations are reported and discussed.

11 T Twin-Aperture Nb$_3$Sn Dipole Development for LHC Upgrades

Energy Technology Data Exchange (ETDEWEB)

Zlobin, A. V. [Fermilab; Andreev, N. [Fermilab; Apollinari, G. [Fermilab; Auchmann, B. [CERN; Barzi, E. [Fermilab; Izquierdo Bermudez, S. [CERN; Bossert, R. [Fermilab; Buehler, M. [Fermilab; Chlachidze, G. [Fermilab; DiMarco, J. [Fermilab; Karppinen, M. [CERN; Nobrega, F. [Fermilab; Novitski, I. [CERN; Rossi, L. [CERN; Smekens, D. [CERN; Tartaglia, M. [Fermilab; Turrioni, D. [Fermilab; Velev, Genadi [Fermilab

2015-01-01

FNAL and CERN are developing a twin-aperture 11 T Nb3Sn dipole suitable for installation in the LHC. This paper describes the design and parameters of the 11 T dipole developed at FNAL for the LHC upgrades in both single-aperture and twin-aperture configurations, and presents details of the constructed dipole models. Results of studies of magnet quench performance, quench protection and magnetic measurements performed using short 1 m long coils in the dipole mirror and single-aperture configurations are reported and discussed.

A functional probe with bowtie aperture and bull's eye structure for nanolithograph

International Nuclear Information System (INIS)

Wang Shuo; Wang Qiao; Guo Ying-Yan; Pan Shi; Li Xu-Feng

2012-01-01

The bowtie aperture surrounded by concentric gratings (the bull's eye structure) integrated on the near-field scanning optical microscopy (NSOM) probe (aluminum coated fiber tip) for nanolithography has been investigated using the finite-difference time domain (FDTD) method. By modifying the parameters of the bowtie aperture and the concentric gratings, a maximal field enhancement factor of 391.69 has been achieved, which is 18 times larger than that obtained from the single bowtie aperture. Additionally, the light spot depends on the gap size of the bowtie aperture and can be confined to sub-wavelength. The superiority of the combination of the bowtie aperture and the bull's eye structure is confirmed, and the mechanism for the electric field enhancement in this derived structure is analyzed

A functional probe with bowtie aperture and bull's eye structure for nanolithograph

Science.gov (United States)

Wang, Shuo; Li, Xu-Feng; Wang, Qiao; Guo, Ying-Yan; Pan, Shi

2012-10-01

The bowtie aperture surrounded by concentric gratings (the bull's eye structure) integrated on the near-field scanning optical microscopy (NSOM) probe (aluminum coated fiber tip) for nanolithography has been investigated using the finite-difference time domain (FDTD) method. By modifying the parameters of the bowtie aperture and the concentric gratings, a maximal field enhancement factor of 391.69 has been achieved, which is 18 times larger than that obtained from the single bowtie aperture. Additionally, the light spot depends on the gap size of the bowtie aperture and can be confined to sub-wavelength. The superiority of the combination of the bowtie aperture and the bull's eye structure is confirmed, and the mechanism for the electric field enhancement in this derived structure is analyzed.

Tibial valgus aperture osteotomy

International Nuclear Information System (INIS)

De los Rios G, Adolfo Leon; Saavedra Abadia, Adolfo Leon; Palacios, Julio

2005-01-01

This study is based on work carried out a The knee clinic at the arthroscopic surgery unit of the Institute of osteo-articular diseases, Imbanaco Medical Centre, The University Hospital of the Valle (Cali-Colombia) and The Fractures Clinic Ltd. (Palmira-Valle). This is a descriptive study, which demonstrates very positive outcomes for aperture osteotomy, without detracting from the importance of, and the progress made in uni-compartmental and total joint articular replacements of the knee. 10 patients were treated with a highs tibial open osteotomy between November 1988 and December 2002: 3 had post-traumatic deformities, without arthrosic alterations; 1 had pseudo-arthrosis caused by a failed corrective procedure; 1 had complex instability of the knee with osseous varus; 6 had a degenerative lesion of the medial meniscus with medial condral alterations. Follow-up was form 12 to 54 months. Treatment involved a tibial valgus aperture osteotomy and osteo-synthesis. Evaluation was carried out using the International Knee Documentation Committee (IKDC) scale, the For Special Surgery and The Knee Society Score

Resource use and efficiency, and stomatal responses to environmental drivers of oak and pine species in an Atlantic Coastal Plain forest

Directory of Open Access Journals (Sweden)

Heidi J Renninger

2015-05-01

Full Text Available Pine-oak ecosystems are globally distributed even though differences in anatomy and leaf habit between many co-occurring oaks and pines suggest different strategies for resource use, efficiency and stomatal behavior. The New Jersey Pinelands contain sandy soils with low water- and nutrient-holding capacity providing an opportunity to examine trade-offs in resource uptake and efficiency. Therefore, we compared resource use in terms of transpiration rates and leaf nitrogen content and resource-use efficiency including water-use efficiency (WUE via gas exchange and leaf carbon isotopes and photosynthetic nitrogen-use efficiency (PNUE between oaks (Quercus alba, Q. prinus, Q. velutina and pines (Pinus rigida, P. echinata. We also determined environmental drivers (vapor pressure deficit (VPD, soil moisture, solar radiation of canopy stomatal conductance (GS estimated via sap flow and stomatal sensitivity to light and soil moisture. Net assimilation rates were similar between genera, but oak leaves used about 10% more water and pine foliage contained about 20% more N per unit leaf area. Therefore, oaks exhibited greater PNUE while pines had higher WUE based on gas exchange, although WUE from carbon isotopes was not significantly different. For the environmental drivers of GS, oaks had about 10% lower stomatal sensitivity to VPD normalized by reference stomatal conductance compared with pines. Pines exhibited a significant positive relationship between shallow soil moisture and GS, but only GS in Q. velutina was positively related to soil moisture. In contrast, stomatal sensitivity to VPD was significantly related to solar radiation in all oak species but only pines at one site. Therefore, oaks rely more heavily on groundwater resources but have lower WUE, while pines have larger leaf areas and nitrogen acquisition but lower PNUE demonstrating a trade-off between using water and nitrogen efficiently in a resource-limited ecosystem.

Resource use and efficiency, and stomatal responses to environmental drivers of oak and pine species in an Atlantic Coastal Plain forest.

Science.gov (United States)

Renninger, Heidi J; Carlo, Nicholas J; Clark, Kenneth L; Schäfer, Karina V R

2015-01-01

Pine-oak ecosystems are globally distributed even though differences in anatomy and leaf habit between many co-occurring oaks and pines suggest different strategies for resource use, efficiency and stomatal behavior. The New Jersey Pinelands contain sandy soils with low water- and nutrient-holding capacity providing an opportunity to examine trade-offs in resource uptake and efficiency. Therefore, we compared resource use in terms of transpiration rates and leaf nitrogen content and resource-use efficiency including water-use efficiency (WUE) via gas exchange and leaf carbon isotopes and photosynthetic nitrogen-use efficiency (PNUE) between oaks (Quercus alba, Q. prinus, Q. velutina) and pines (Pinus rigida, P. echinata). We also determined environmental drivers [vapor pressure deficit (VPD), soil moisture, solar radiation] of canopy stomatal conductance (GS) estimated via sap flow and stomatal sensitivity to light and soil moisture. Net assimilation rates were similar between genera, but oak leaves used about 10% more water and pine foliage contained about 20% more N per unit leaf area. Therefore, oaks exhibited greater PNUE while pines had higher WUE based on gas exchange, although WUE from carbon isotopes was not significantly different. For the environmental drivers of GS, oaks had about 10% lower stomatal sensitivity to VPD normalized by reference stomatal conductance compared with pines. Pines exhibited a significant positive relationship between shallow soil moisture and GS, but only GS in Q. velutina was positively related to soil moisture. In contrast, stomatal sensitivity to VPD was significantly related to solar radiation in all oak species but only pines at one site. Therefore, oaks rely more heavily on groundwater resources but have lower WUE, while pines have larger leaf areas and nitrogen acquisition but lower PNUE demonstrating a trade-off between using water and nitrogen efficiently in a resource-limited ecosystem.

What determines the complex kinetics of stomatal conductance under blueless PAR in Festuca arundinacea? Subsequent effects on leaf transpiration.

Science.gov (United States)

Barillot, Romain; Frak, Ela; Combes, Didier; Durand, Jean-Louis; Escobar-Gutiérrez, Abraham J

2010-06-01

Light quality and, in particular, its content of blue light is involved in plant functioning and morphogenesis. Blue light variation frequently occurs within a stand as shaded zones are characterized by a simultaneous decrease of PAR and blue light levels which both affect plant functioning, for example, gas exchange. However, little is known about the effects of low blue light itself on gas exchange. The aims of the present study were (i) to characterize stomatal behaviour in Festuca arundinacea leaves through leaf gas exchange measurements in response to a sudden reduction in blue light, and (ii) to test the putative role of Ci on blue light gas exchange responses. An infrared gas analyser (IRGA) was used with light transmission filters to study stomatal conductance (gs), transpiration (Tr), assimilation (A), and intercellular concentration of CO(2) (Ci) responses to blueless PAR (1.80 mumol m(-2) s(-1)). The results were compared with those obtained under a neutral filter supplying a similar photosynthetic efficiency to the blueless PAR filter. It was shown that the reduction of blue light triggered a drastic and instantaneous decrease of gs by 43.2% and of Tr by 40.0%, but a gradual stomatal reopening began 20 min after the start of the low blue light treatment, thus leading to new steady-states. This new stomatal equilibrium was supposed to be related to Ci. The results were confirmed in more developed plants although they exhibited delayed and less marked responses. It is concluded that stomatal responses to blue light could play a key role in photomorphogenetic mechanisms through their effect on transpiration.

Contribution of competition for light to within-species variability in stomatal conductance

Science.gov (United States)

Loranty, Michael M.; Mackay, D. Scott; Ewers, Brent E.; Traver, Elizabeth; Kruger, Eric L.

2010-05-01

Sap flux (JS) measurements were collected across two stands dominated by either trembling aspen or sugar maple in northern Wisconsin. Observed canopy transpiration (EC-obs) values derived from JS were used to parameterize the Terrestrial Regional Ecosystem Exchange Simulator ecosystem model. Modeled values of stomatal conductance (GS) were used to determine reference stomatal conductance (GSref), a proxy for GS that removes the effects of temporal responses to vapor pressure deficit (D) on spatial patterns of GS. Values of GSref were compared to observations of soil moisture, several physiological variables, and a competition index (CI) derived from a stand inventory, to determine the underlying cause of observed variability. Considerable variability in GSref between individual trees was found, with values ranging from 20 to 200 mmol m-2 s-1 and 20 to 100 mmol m-2 s-1 at the aspen and maple stands, respectively. Model-derived values of GSref and a sensitivity to D parameter (m) showed good agreement with a known empirical relationship for both stands. At both sites, GSref did not vary with topographic position, as indicated by surface soil moisture. No relationships were observed between GSref and tree height (HT), and a weak correlation with sapwood area (AS) was only significant for aspen. Significant nonlinear inverse relationships between GSref and CI were observed at both stands. Simulations with uniform reductions in incident photosynthetically active radiation (Q0) resulted in better agreement between observed and simulated EC. Our results suggest a link between photosynthesis and plant hydraulics whereby individual trees subject to photosynthetic limitation as a result of competitive shading exhibit a dynamic stomatal response resulting in a more conservative strategy for managing hydrologic resources.

Application of Ruze Equation for Inflatable Aperture Antennas

Science.gov (United States)

Welch, Bryan W.

2008-01-01

Inflatable aperture reflector antennas are an emerging technology that NASA is investigating for potential uses in science and exploration missions. As inflatable aperture antennas have not been proven fully qualified for space missions, they must be characterized properly so that the behavior of the antennas can be known in advance. To properly characterize the inflatable aperture antenna, testing must be performed in a relevant environment, such as a vacuum chamber. Since the capability of having a radiofrequency (RF) test facility inside a vacuum chamber did not exist at NASA Glenn Research Center, a different methodology had to be utilized. The proposal to test an inflatable aperture antenna in a vacuum chamber entailed performing a photogrammetry study of the antenna surface by using laser ranging measurements. A root-mean-square (rms) error term was derived from the photogrammetry study to calculate the antenna surface loss as described by the Ruze equation. However, initial testing showed that problems existed in using the Ruze equation to calculate the loss due to errors on the antenna surface. This study utilized RF measurements obtained in a near-field antenna range and photogrammetry data taken from a laser range scanner to compare the expected performance of the test antenna (via the Ruze equation) with the actual RF patterns and directivity measurements. Results showed that the Ruze equation overstated the degradation in the directivity calculation. Therefore, when the photogrammetry study is performed on the test antennas in the vacuum chamber, a more complex equation must be used in light of the fact that the Ruze theory overstates the loss in directivity for inflatable aperture reflector antennas.

Dynamic Aperture Studies for SPEAR 3

International Nuclear Information System (INIS)

Corbett, William

1998-01-01

The Stanford Synchrotron Radiation Laboratory is investigating an accelerator upgrade project that would replace the present 130 nm rad FODO lattice with an 18 nm rad double bend achromat (DBA) lattice: SPEAR 3. The low emittance design yields a high brightness beam, but the stronger focusing in the DBA lattice increases chromaticity and beam sensitivity to machine errors. To ensure efficient injection and long Touschek lifetime, an optimization of the design lattice and dynamic aperture has been performed. In this paper, we review the methods used to maximize the SPEAR 3 dynamic aperture including necessary optics modifications, choice of tune and phase advance, optimization of sextupole and coupling correction, and modeling effects of machine errors, wigglers and lattice periodicity

Simulation of an aperture-based antihydrogen gravity experiment

Directory of Open Access Journals (Sweden)

C. A. Ordonez

2012-03-01

Full Text Available A Monte Carlo simulation is presented of an experiment that could potentially determine whether antihydrogen accelerates vertically up or down as a result of earth's gravity. The experiment would rely on methods developed by existing antihydrogen research collaborations and would employ a Penning trap for the production of antihydrogen within a uniform magnetic field. The axis of symmetry of the cylindrical trap wall would be oriented horizontally, and an axisymmetric aperture (with an inner radius that is smaller than the cylindrical trap wall radius would be present a short distance away from the antihydrogen production region. Antihydrogen annihilations that occur along the cylindrical trap wall would be detected by the experiment. The distribution of annihilations along the wall would vary near the aperture, because some antihydrogen that would otherwise annihilate at the wall would instead annihilate on the aperture. That is, a shadow region forms behind the aperture, and the distribution of annihilations near the boundary of the shadow region is not azimuthally symmetric when the effect of gravity is significant. The Monte Carlo simulation is used together with analytical modeling to determine conditions under which the annihilation distribution would indicate the direction of the acceleration of antihydrogen due to gravity.

Development of procedures for programmable proximity aperture lithography

Energy Technology Data Exchange (ETDEWEB)

Whitlow, H.J., E-mail: harry.whitlow@he-arc.ch [Institut des Microtechnologies Appliquées Arc, Haute Ecole Arc Ingénierie, Eplatures-Grise 17, CH-2300 La Chaux-de-Fonds (Switzerland); Department of Physics, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 Jyväskylä (Finland); Gorelick, S. [VTT Technical Research Centre of Finland, P.O. Box 1000, Tietotie 3, Espoo, FI-02044 VTT (Finland); Puttaraksa, N. [Department of Physics, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 Jyväskylä (Finland); Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Napari, M.; Hokkanen, M.J.; Norarat, R. [Department of Physics, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 Jyväskylä (Finland)

2013-07-01

Programmable proximity aperture lithography (PPAL) with MeV ions has been used in Jyväskylä and Chiang Mai universities for a number of years. Here we describe a number of innovations and procedures that have been incorporated into the LabView-based software. The basic operation involves the coordination of the beam blanker and five motor-actuated translators with high accuracy, close to the minimum step size with proper anti-collision algorithms. By using special approaches, such writing calibration patterns, linearisation of position and careful backlash correction the absolute accuracy of the aperture size and position, can be improved beyond the standard afforded by the repeatability of the translator end-point switches. Another area of consideration has been the fluence control procedures. These involve control of the uniformity of the beam where different approaches for fluence measurement such as simultaneous aperture current and the ion current passing through the aperture using a Faraday cup are used. Microfluidic patterns may contain many elements that make-up mixing sections, reaction chambers, separation columns and fluid reservoirs. To facilitate conception and planning we have implemented a .svg file interpreter, that allows the use of scalable vector graphics files produced by standard drawing software for generation of patterns made up of rectangular elements.

Control of aperture closure during reach-to-grasp movements in Parkinson's disease.

Science.gov (United States)

Rand, M K; Smiley-Oyen, A L; Shimansky, Y P; Bloedel, J R; Stelmach, G E

2006-01-01

This study examined whether the pattern of coordination between arm-reaching toward an object (hand transport) and the initiation of aperture closure for grasping is different between PD patients and healthy individuals, and whether that pattern is affected by the necessity to quickly adjust the reach-to-grasp movement in response to an unexpected shift of target location. Subjects reached for and grasped a vertical dowel, the location of which was indicated by illuminating one of the three dowels placed on a horizontal plane. In control conditions, target location was fixed during the trial. In perturbation conditions, target location was shifted instantaneously by switching the illumination to a different dowel during the reach. The hand distance from the target at which the subject initiated aperture closure (aperture closure distance) was similar for both the control and perturbation conditions within each group of subjects. However, that distance was significantly closer to the target in the PD group than in the control group. The timing of aperture closure initiation varied considerably across the trials in both groups of subjects. In contrast, aperture closure distance was relatively invariant, suggesting that aperture closure initiation was determined by spatial parameters of arm kinematics rather than temporal parameters. The linear regression analysis of aperture closure distance showed that the distance was highly predictable based on the following three parameters: the amplitude of maximum grip aperture, hand velocity, and hand acceleration. This result implies that a control law, the arguments of which include the above parameters, governs the initiation of aperture closure. Further analysis revealed that the control law was very similar between the subject groups under each condition as well as between the control and perturbation conditions for each group. Consequently, the shorter aperture closure distance observed in PD patients apparently is a

Central obscuration effects on optical synthetic aperture imaging

Science.gov (United States)

Wang, Xue-wen; Luo, Xiao; Zheng, Li-gong; Zhang, Xue-jun

2014-02-01

Due to the central obscuration problem exists in most optical synthetic aperture systems, it is necessary to analyze its effects on their image performance. Based on the incoherent diffraction limited imaging theory, a Golay-3 type synthetic aperture system was used to study the central obscuration effects on the point spread function (PSF) and the modulation transfer function (MTF). It was found that the central obscuration does not affect the width of the central peak of the PSF and the cutoff spatial frequency of the MTF, but attenuate the first sidelobe of the PSF and the midfrequency of the MTF. The imaging simulation of a Golay-3 type synthetic aperture system with central obscuration proved this conclusion. At last, a Wiener Filter restoration algorithm was used to restore the image of this system, the images were obviously better.

Synthetic aperture integration (SAI) algorithm for SAR imaging

Science.gov (United States)

Chambers, David H; Mast, Jeffrey E; Paglieroni, David W; Beer, N. Reginald

2013-07-09

A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

Plasmonic nanofocusing with a metallic pyramid and an integrated C-shaped aperture

Science.gov (United States)

Lindquist, Nathan C.; Johnson, Timothy W.; Nagpal, Prashant; Norris, David J.; Oh, Sang-Hyun

2013-05-01

We demonstrate the design, fabrication and characterization of a near-field plasmonic nanofocusing probe with a hybrid tip-plus-aperture design. By combining template stripping with focused ion beam lithography, a variety of aperture-based near-field probes can be fabricated with high optical performance. In particular, the combination of large transmission through a C-shaped aperture aligned to the sharp apex (<10 nm radius) of a template-stripped metallic pyramid allows the efficient delivery of light--via the C-shaped aperture--while providing a nanometric hotspot determined by the sharpness of the tip itself.

Large aperture components for solid state laser fusion systems

International Nuclear Information System (INIS)

Simmons, W.W.

1978-01-01

Solid state lasers for fusion experiments must reliably deliver maximum power to small (approximately .5 mm) targets from stand-off focal distances of 1 m or more. This requirement places stringent limits upon the optical quality, resistance to damage, and overall performance of the several major components--amplifiers, Faraday isolators, spatial filters--in each amplifier train. Component development centers about achieving (1) highest functional material figure of merit, (2) best optical quality, and (3) maximum resistance to optical damage. Specific examples of the performance of large aperture components will be presented within the context of the Argus and Shiva laser systems, which are presently operational at Lawrence Livermore Laboratory. Shiva comprises twenty amplifiers, each of 20 cm output clear aperture. Terawatt beams from these amplifiers are focused through two opposed, nested clusters of f/6 lenses onto such targets. Design requirements upon the larger aperture Nova laser components, up to 35 cm in clear aperture, will also be discussed; these pose a significant challenge to the optical industry

Electrical signaling, stomatal conductance, ABA and Ethylene content in avocado trees in response to root hypoxia

Science.gov (United States)

Gurovich, Luis; Schaffer, Bruce; García, Nicolás; Iturriaga, Rodrigo

2009-01-01

Avocado (Persea americana Mill.) trees are among the most sensitive of fruit tree species to root hypoxia as a result of flooded or poorly drained soil. Similar to drought stress, an early physiological response to root hypoxia in avocado is a reduction of stomatal conductance. It has been previously determined in avocado trees that an extracellular electrical signal between the base of stem and leaves is produced and related to reductions in stomatal conductance in response to drought stress. The current study was designed to determine if changes in the extracellular electrical potential between the base of the stem and leaves in avocado trees could also be detected in response to short-term (min) or long-term (days) root hypoxia, and if these signals could be related to stomatal conductance (gs), root and leaf ABA and ACC concentrations, ethylene emission from leaves and leaf abscission. In contrast to previous observations for drought-stressed trees, short-term or long-term root hypoxia did not stimulate an electrical potential difference between the base of the stem and leaves. Short-term hypoxia did not result in a significant decrease in gs compared with plants in the control treatment, and no differences in ABA concentration were found between plants subjected to hypoxia and control plants. Long-term hypoxia in the root zone resulted in a significant decrease in gs, increased leaf ethylene and increased leaf abscission. The results indicate that for avocado trees exposed to root hypoxia, electrical signals do not appear to be the primary root-to-shoot communication mechanism involved in signaling for stomatal closure as a result of hypoxia in the root zone. PMID:19649181

Terahertz near-field imaging using subwavelength plasmonic apertures and a quantum cascade laser source.

Science.gov (United States)

Baragwanath, Adam J; Freeman, Joshua R; Gallant, Andrew J; Zeitler, J Axel; Beere, Harvey E; Ritchie, David A; Chamberlain, J Martyn

2011-07-01

The first demonstration, to our knowledge, of near-field imaging using subwavelength plasmonic apertures with a terahertz quantum cascade laser source is presented. "Bull's-eye" apertures, featuring subwavelength circular apertures flanked by periodic annular corrugations were created using a novel fabrication method. A fivefold increase in intensity was observed for plasmonic apertures over plain apertures of the same diameter. Detailed studies of the transmitted beam profiles were undertaken for apertures with both planarized and corrugated exit facets, with the former producing spatially uniform intensity profiles and subwavelength spatial resolution. Finally, a proof-of-concept imaging experiment is presented, where an inhomogeneous pharmaceutical drug coating is investigated.

Particle-in-Cell Modeling of Magnetized Argon Plasma Flow Through Small Mechanical Apertures

Energy Technology Data Exchange (ETDEWEB)

Adam B. Sefkow and Samuel A. Cohen

2009-04-09

Motivated by observations of supersonic argon-ion flow generated by linear helicon-heated plasma devices, a three-dimensional particle-in-cell (PIC) code is used to study whether stationary electrostatic layers form near mechanical apertures intersecting the flow of magnetized plasma. By self-consistently evaluating the temporal evolution of the plasma in the vicinity of the aperture, the PIC simulations characterize the roles of the imposed aperture and applied magnetic field on ion acceleration. The PIC model includes ionization of a background neutral-argon population by thermal and superthermal electrons, the latter found upstream of the aperture. Near the aperture, a transition from a collisional to a collisionless regime occurs. Perturbations of density and potential, with mm wavelengths and consistent with ion acoustic waves, propagate axially. An ion acceleration region of length ~ 200-300 λD,e forms at the location of the aperture and is found to be an electrostatic double layer, with axially-separated regions of net positive and negative charge. Reducing the aperture diameter or increasing its length increases the double layer strength.

Particle-in-Cell Modeling of Magnetized Argon Plasma Flow Through Small Mechanical Apertures

International Nuclear Information System (INIS)

Sefkow, Adam B.; Cohen, Samuel A.

2009-01-01

Motivated by observations of supersonic argon-ion flow generated by linear helicon-heated plasma devices, a three-dimensional particle-in-cell (PIC) code is used to study whether stationary electrostatic layers form near mechanical apertures intersecting the flow of magnetized plasma. By self-consistently evaluating the temporal evolution of the plasma in the vicinity of the aperture, the PIC simulations characterize the roles of the imposed aperture and applied magnetic field on ion acceleration. The PIC model includes ionization of a background neutral-argon population by thermal and superthermal electrons, the latter found upstream of the aperture. Near the aperture, a transition from a collisional to a collisionless regime occurs. Perturbations of density and potential, with mm wavelengths and consistent with ion acoustic waves, propagate axially. An ion acceleration region of length ∼ 200-300 λ D,e forms at the location of the aperture and is found to be an electrostatic double layer, with axially-separated regions of net positive and negative charge. Reducing the aperture diameter or increasing its length increases the double layer strength

On-axis parallel ion speeds near mechanical and magnetic apertures in a helicon plasma device

International Nuclear Information System (INIS)

Sun Xuan; Cohen, S.A.; Scime, Earl E.; Miah, Mahmood

2005-01-01

Using laser-induced fluorescence, measurements of parallel ion velocities were made along the axis of a helicon-generated Ar plasma column whose radius was modified by spatially separated mechanical and magnetic apertures. Ion acceleration to supersonic speeds was observed 0.1-5 cm downstream of both aperture types, simultaneously generating two steady-state double layers (DLs) when both apertures were in place. The DL downstream of the mechanical aperture plate had a larger potential drop, Δφ DL =6-9 kT e , compared to the DL downstream of the magnetic aperture, Δφ DL ∼3 kT e . In the presheath region upstream of the mechanical aperture, the convective ion speed increased over a collisional distance; from stagnant at 4 cm from the aperture to the 1.4 times the sound speed at the aperture. The dependence of the free- and trapped-ion-velocity-distribution functions on the magnetic-field strength and mechanical-aperture electrical bias are also presented

Modeling daily gas exchange of a Douglas-fir forest : comparison of three stomatal conductance models with and without a soil water stress function

NARCIS (Netherlands)

Wijk, van M.T.; Dekker, S.C.; Bouten, W.; Bosveld, F.C.; Kohsiek, W.; Kramer, K.; Mohren, G.M.J.

2000-01-01

Modeling stomatal conductance is a key element in predicting tree growth and water use at the stand scale. We compared three commonly used models of stomatal conductance, the Jarvis-Loustau, Ball-Berry and Leuning models, for their suitability for incorporating soil water stress into their

Photosynthesis down-regulation precedes carbohydrate accumulation under sink limitation in Citrus.

Science.gov (United States)

Nebauer, Sergio G; Renau-Morata, Begoña; Guardiola, José Luis; Molina, Rosa-Victoria

2011-02-01

Photosynthesis down-regulation due to an imbalance between sources and sinks in Citrus leaves could be mediated by excessive accumulation of carbohydrates. However, there is limited understanding of the physiological role of soluble and insoluble carbohydrates in photosynthesis regulation and the elements triggering the down-regulation process. In this work, the role of non-structural carbohydrates in the regulation of photosynthesis under a broad spectrum of source-sink relationships has been investigated in the Salustiana sweet orange. Soluble sugar and starch accumulation in leaves, induced by girdling experiments, did not induce down-regulation of the photosynthetic rate in the presence of sinks (fruits). The leaf-to-fruit ratio did not modulate photosynthesis but allocation of photoassimilates to the fruits. The lack of strong sink activity led to a decrease in the photosynthetic rate and starch accumulation in leaves. However, photosynthesis down-regulation due to an excess of total soluble sugars or starch was discarded because photosynthesis and stomatal conductance reduction occurred prior to any significant accumulation of these carbohydrates. Gas exchange and fluorescence parameters suggested biochemical limitations to photosynthesis. In addition, the expression of carbon metabolism-related genes was altered within 24 h when strong sinks were removed. Sucrose synthesis and export genes were inhibited, whereas the expression of ADP-glucose pyrophosphorylase was increased to cope with the excess of assimilates. In conclusion, changes in starch and soluble sugar turnover, but not sugar content per se, could provide the signal for photosynthesis regulation. In these conditions, non-stomatal limitations strongly inhibited the photosynthetic rate prior to any significant increase in carbohydrate levels.

Global CO2 rise leads to reduced maximum stomatal conductance in Florida vegetation

NARCIS (Netherlands)

Lammertsma, E.I.; de Boer, H.J.; Dekker, S.C.; Dilcher, D.L.; Lotter, A.F.; Wagner-Cremer, F.

2011-01-01

A principle response of C3 plants to increasing concentrations of atmospheric CO2 (CO2) is to reduce transpirational water loss by decreasing stomatal conductance (gs) and simultaneously increase assimilation rates. Via this adaptation, vegetation has the ability to alter hydrology and climate.

Acoustic Source Localization via Subspace Based Method Using Small Aperture MEMS Arrays

Directory of Open Access Journals (Sweden)

Xin Zhang

2014-01-01

Full Text Available Small aperture microphone arrays provide many advantages for portable devices and hearing aid equipment. In this paper, a subspace based localization method is proposed for acoustic source using small aperture arrays. The effects of array aperture on localization are analyzed by using array response (array manifold. Besides array aperture, the frequency of acoustic source and the variance of signal power are simulated to demonstrate how to optimize localization performance, which is carried out by introducing frequency error with the proposed method. The proposed method for 5 mm array aperture is validated by simulations and experiments with MEMS microphone arrays. Different types of acoustic sources can be localized with the highest precision of 6 degrees even in the presence of wind noise and other noises. Furthermore, the proposed method reduces the computational complexity compared with other methods.

Species climate range influences hydraulic and stomatal traits in Eucalyptus species.

Science.gov (United States)

Bourne, Aimee E; Creek, Danielle; Peters, Jennifer M R; Ellsworth, David S; Choat, Brendan

2017-07-01

Plant hydraulic traits influence the capacity of species to grow and survive in water-limited environments, but their comparative study at a common site has been limited. The primary aim of this study was to determine whether selective pressures on species originating in drought-prone environments constrain hydraulic traits among related species grown under common conditions. Leaf tissue water relations, xylem anatomy, stomatal behaviour and vulnerability to drought-induced embolism were measured on six Eucalyptus species growing in a common garden to determine whether these traits were related to current species climate range and to understand linkages between the traits. Hydraulically weighted xylem vessel diameter, leaf turgor loss point, the water potential at stomatal closure and vulnerability to drought-induced embolism were significantly ( P Eucalyptus trees has important implications for the limits of species responses to changing environmental conditions and thus for species survival and distribution into the future, and yields new information for physiological models. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Translation symmetry of the Fraunhofer diffraction pattern from a polygonal aperture

International Nuclear Information System (INIS)

Vinogradov, I.R.; Tarlykov, V.A.

1995-01-01

The problem of observing the translation symmetry in the Fraunhofer diffraction pattern is treated. The objective of this study is to show that translation symmetry can be observed in the Fraunhofer diffraction pattern if the diffraction aperture can be represented in the form of a set of parallelogram apertures. It is shown that the diffraction field produced by such an aperture can be represented as a system of point sources modulated with an amplitude factor. 10 refs., 2 figs

Dynamic aperture studies for SPEAR 3

International Nuclear Information System (INIS)

Nosochkov, Y.; Corbett, J.

1999-01-01

The Stanford Synchrotron Radiation Laboratory is investigating an accelerator upgrade project that would replace the present 130 nm·rad FODO lattice with an 18 nm·rad double bend achromat (DBA) lattice: SPEAR 3. The low emittance design yields a high brightness beam, but the stronger focusing in the DBA lattice increases chromaticity and beam sensitivity to machine errors. To ensure efficient injection and long Touschek lifetime, an optimization of the design lattice and dynamic aperture has been performed. In this paper, we review the methods used to maximize the SPEAR 3 dynamic aperture including necessary optics modifications, choice of tune and phase advance, optimization of sextupole and coupling correction, and modeling effects of machine errors, wigglers and lattice periodicity

Transmission of high-power electron beams through small apertures

International Nuclear Information System (INIS)

Tschalär, C.; Alarcon, R.; Balascuta, S.; Benson, S.V.; Bertozzi, W.; Boyce, J.R.; Cowan, R.; Douglas, D.; Evtushenko, P.; Fisher, P.; Ihloff, E.; Kalantarians, N.; Kelleher, A.; Legg, R.; Milner, R.G.; Neil, G.R.; Ou, L.; Schmookler, B.; Tennant, C.; Williams, G.P.

2013-01-01

Tests were performed to pass a 100 MeV, 430 kWatt c.w. electron beam from the energy-recovery linac at the Jefferson Laboratory's FEL facility through a set of small apertures in a 127 mm long aluminum block. Beam transmission losses of 3 p.p.m. through a 2 mm diameter aperture were maintained during a 7 h continuous run

Diurnal regulation of photosynthesis in Jatropha curcas under drought during summer in a semi-arid region

International Nuclear Information System (INIS)

Tominaga, Jun; Inafuku, Sayuri; Coetzee, Tidimalo; Kawamitsu, Yoshinobu

2014-01-01

The diurnal photosynthetic responses to drought in Jatropha curcas have not been well assessed under field conditions in harsh semi-arid habitats. To illustrate this, diurnal changes in chlorophyll fluorescence and gas exchange rates were measured in field-grown Jatropha with or without a short (13 days) water recovery treatment under drought conditions during hot summer in a semi-arid. Sensitive stomatal closure coordinated with a drying atmosphere strictly limited a net CO 2 assimilation rate with a predominant morning peak, eventually turning negative during the day. Even though the risk of excess excitation energy which potentially causes photodamage increased with the extremely low capacity for CO 2 fixation, Jatropha preserved the integrity of PSII. Quantitative analysis of quenching partitioning revealed that regulated thermal energy dissipation accounted a large fraction of both instantaneous and daily absorbed energy by up to 80 and 72%, respectively, under the drought condition. Water recovery treatment more than doubled daily CO 2 uptake via mitigating diurnal stomatal closure. The regulated thermal dissipation flexibly adjusted PSII quantum efficiency to capacity of CO 2 fixation. In addition, downregulation of PSII quantum efficiency via sustained regulated thermal dissipation was observed and thought to be an additional photoprotective function. It is clear that Jatropha strongly rely upon the regulated thermal dissipation under drought condition, which must be critically important for this strict water conserving species, especially under a climate with high solar radiation loads as is seen in semi-arid regions. - Highlights: • Diurnal gas exchange and the fate of absorbed energy were assessed in Jatropha. • The dynamic stomatal closure was the predominant restriction under water stress. • The PSII integrity was preserved even under severe water stress. • The regulated thermal dissipation accounted by up to 72% of daily absorbed energy. �

Simulation of stomatal conductance for Aleppo pine to estimate its ozone uptake

Energy Technology Data Exchange (ETDEWEB)

Elvira, Susana [Ecotoxicology of Air Pollution, CIEMAT, Avda. Complutense 22 (ed. 70), 28040 Madrid (Spain); Alonso, Rocio [Ecotoxicology of Air Pollution, CIEMAT, Avda. Complutense 22 (ed. 70), 28040 Madrid (Spain); Gimeno, Benjamin S. [Ecotoxicology of Air Pollution, CIEMAT, Avda. Complutense 22 (ed. 70), 28040 Madrid (Spain)]. E-mail: benjamin.gimeno@ciemat.es

2007-04-15

The data from a previous experiment carried out in open-top chambers to assess the effects of ozone (O{sub 3}) exposure on growth and physiology of Aleppo pine (Pinus halepensis Mill.) were re-assessed to test the performance of the EMEP O{sub 3} stomatal conductance model used to estimate tree O{sub 3} uptake at a European scale. Aleppo pine seedlings were exposed during three consecutive years to three different O{sub 3} treatments: charcoal filtered air, non-filtered air and non-filtered air supplemented with 40 nl l{sup -1}. The results of the model using the default parameterisation already published for Mediterranean conifers showed a poor performance when compared to measured data. Therefore, modifications of g {sub max}, f {sub min}, and new f {sub VPD}, f {sub temp} and f {sub phen} functions were developed according to the observed data. This re-parameterisation resulted in a significant improvement of the performance of the model when compared to its original version. - Current EMEP stomatal uptake module needs to be re-parameterised for Mediterranean tree species.

Simulation of stomatal conductance for Aleppo pine to estimate its ozone uptake

International Nuclear Information System (INIS)

Elvira, Susana; Alonso, Rocio; Gimeno, Benjamin S.

2007-01-01

The data from a previous experiment carried out in open-top chambers to assess the effects of ozone (O 3 ) exposure on growth and physiology of Aleppo pine (Pinus halepensis Mill.) were re-assessed to test the performance of the EMEP O 3 stomatal conductance model used to estimate tree O 3 uptake at a European scale. Aleppo pine seedlings were exposed during three consecutive years to three different O 3 treatments: charcoal filtered air, non-filtered air and non-filtered air supplemented with 40 nl l -1 . The results of the model using the default parameterisation already published for Mediterranean conifers showed a poor performance when compared to measured data. Therefore, modifications of g max , f min , and new f VPD , f temp and f phen functions were developed according to the observed data. This re-parameterisation resulted in a significant improvement of the performance of the model when compared to its original version. - Current EMEP stomatal uptake module needs to be re-parameterised for Mediterranean tree species

Quench Performance of the First Twin-aperture 11 T Dipole for LHC upgrades

CERN Document Server

Zlobin, A V; Apollinari, G; Barzi, E; Chlachidze, G; Nobrega, A; Novitski, I; Stoynev, S; Turrioni, D; Auchmann, B; Izquierdo Bermudez, S; Karppinen, M; Rossi, L; Savary, F; Smekens, D

2015-01-01

FNAL and CERN are developing a twin-aperture 11 T Nb$_{3}$Sn dipole suitable for installation in the LHC. A single-aperture 2-m long dipole demonstrator and two 1-m long dipole models have been fabricated and tested at FNAL in 2012-2014. The two 1 m long collared coils were then assembled into the first twin-aperture Nb$_{3}$Sn demonstrator dipole and tested. Test results of this twin-aperture Nb$_{3}$Sn dipole model are reported and discussed.

Stomatal vs. genome size in angiosperms: the somatic tail wagging the genomic dog?

NARCIS (Netherlands)

Hodgson, J.G.; Sharafi, M.; Jalili, A.; Diaz, S.; Montserrat-Marti, G.; Palmer, C.; Cerabolini, B.; Pierce, S.; Hamzehee, B.; Asri, Y.; Jamzad, Z.; Wilson, P.; Zarrinkamar, F.; Raven, J.; Band, S.R.; Basconcelo, S.; Bogard, A.; Carter, G.; Charles, M.; Castro-Diez, P.; Cornelissen, J.H.C.; Funes, G.; Jones, M.; Khoshnevis, M.; Perez-Harguindeguy, N.; Perez-Rontome, M.C.; Shirvany, F.A.; Vendramini, F.; Yazdani, S.; Abbas-Azimi, R.; Boustani, S.; Dehghan, M.; Hynd, F.A.; Kowsary, E.; Kazemi-Saeed, F.; Siavash, B.; Villar-Salvador, P.; Cragie, R.; Naqinezhad, A.; Romo-Diez, A.; De Torres Espuny, L.; Simmons, E.

2010-01-01

Background and Aims Genome size is a function, and the product, of cell volume. As such it is contingent on ecological circumstance. The nature of 'this ecological circumstance' is, however, hotly debated. Here, we investigate for angiosperms whether stomatal size may be this 'missing link': the

Optimization of Dynamic Aperture of PEP-X Baseline Design

Energy Technology Data Exchange (ETDEWEB)

Wang, Min-Huey; /SLAC; Cai, Yunhai; /SLAC; Nosochkov, Yuri; /SLAC

2010-08-23

SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing photon source. Storage ring design is one of the possibilities that would be housed in the 2.2-km PEP-II tunnel. The design goal of PEPX storage ring is to approach an optimal light source design with horizontal emittance less than 100 pm and vertical emittance of 8 pm to reach the diffraction limit of 1-{angstrom} x-ray. The low emittance design requires a lattice with strong focusing leading to high natural chromaticity and therefore to strong sextupoles. The latter caused reduction of dynamic aperture. The dynamic aperture requirement for horizontal injection at injection point is about 10 mm. In order to achieve the desired dynamic aperture the transverse non-linearity of PEP-X is studied. The program LEGO is used to simulate the particle motion. The technique of frequency map is used to analyze the nonlinear behavior. The effect of the non-linearity is tried to minimize at the given constrains of limited space. The details and results of dynamic aperture optimization are discussed in this paper.

Optimization of Dynamic Aperture of PEP-X Baseline Design

International Nuclear Information System (INIS)

Wang, Min-Huey

2010-01-01

SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing photon source. Storage ring design is one of the possibilities that would be housed in the 2.2-km PEP-II tunnel. The design goal of PEPX storage ring is to approach an optimal light source design with horizontal emittance less than 100 pm and vertical emittance of 8 pm to reach the diffraction limit of 1-(angstrom) x-ray. The low emittance design requires a lattice with strong focusing leading to high natural chromaticity and therefore to strong sextupoles. The latter caused reduction of dynamic aperture. The dynamic aperture requirement for horizontal injection at injection point is about 10 mm. In order to achieve the desired dynamic aperture the transverse non-linearity of PEP-X is studied. The program LEGO is used to simulate the particle motion. The technique of frequency map is used to analyze the nonlinear behavior. The effect of the non-linearity is tried to minimize at the given constrains of limited space. The details and results of dynamic aperture optimization are discussed in this paper.

Comparison of PSF maxima and minima of multiple annuli coded aperture (MACA) and complementary multiple annuli coded aperture (CMACA) systems

Science.gov (United States)

Ratnam, Challa; Lakshmana Rao, Vadlamudi; Lachaa Goud, Sivagouni

2006-10-01

In the present paper, and a series of papers to follow, the Fourier analytical properties of multiple annuli coded aperture (MACA) and complementary multiple annuli coded aperture (CMACA) systems are investigated. First, the transmission function for MACA and CMACA is derived using Fourier methods and, based on the Fresnel-Kirchoff diffraction theory, the formulae for the point spread function are formulated. The PSF maxima and minima are calculated for both the MACA and CMACA systems. The dependence of these properties on the number of zones is studied and reported in this paper.

Comparison of PSF maxima and minima of multiple annuli coded aperture (MACA) and complementary multiple annuli coded aperture (CMACA) systems

International Nuclear Information System (INIS)

Ratnam, Challa; Rao, Vadlamudi Lakshmana; Goud, Sivagouni Lachaa

2006-01-01

In the present paper, and a series of papers to follow, the Fourier analytical properties of multiple annuli coded aperture (MACA) and complementary multiple annuli coded aperture (CMACA) systems are investigated. First, the transmission function for MACA and CMACA is derived using Fourier methods and, based on the Fresnel-Kirchoff diffraction theory, the formulae for the point spread function are formulated. The PSF maxima and minima are calculated for both the MACA and CMACA systems. The dependence of these properties on the number of zones is studied and reported in this paper

Design of a hybrid double-sideband/single-sideband (schlieren) objective aperture suitable for electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Buijsse, Bart; Laarhoven, Frank M.H.M. van [FEI Company, PO Box 80066, 5600 KA Eindhoven (Netherlands); Schmid, Andreas K.; Cambie, Rossana; Cabrini, Stefano; Jin, Jian [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Glaeser, Robert M., E-mail: rmglaeser@lbl.gov [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States)

2011-12-15

A novel design is described for an aperture that blocks a half-plane of the electron diffraction pattern out to a desired scattering angle, and then - except for a narrow support beam - transmits all of the scattered electrons beyond that angle. Our proposed tulip-shaped design is thus a hybrid between the single-sideband (ssb) aperture, which blocks a full half-plane of the diffraction pattern, and the conventional (i.e. fully open) double-sideband (dsb) aperture. The benefits of this hybrid design include the fact that such an aperture allows one to obtain high-contrast images of weak-phase objects with the objective lens set to Scherzer defocus. We further demonstrate that such apertures can be fabricated from thin-foil materials by milling with a focused ion beam (FIB), and that such apertures are fully compatible with the requirements of imaging out to a resolution of at least 0.34 nm. As is known from earlier work with single-sideband apertures, however, the edge of such an aperture can introduce unwanted, electrostatic phase shifts due to charging. The principal requirement for using such an aperture in a routine data-collection mode is thus to discover appropriate materials, protocols for fabrication and processing and conditions of use such that the hybrid aperture remains free of charging over long periods of time. -- Highlights: Black-Right-Pointing-Pointer New objective-aperture design is proposed for imaging weak-phase objects. Black-Right-Pointing-Pointer Design produces single-sideband contrast at low spatial frequencies. Black-Right-Pointing-Pointer Design also retains Scherzer-defocus phase contrast at higher resolution. Black-Right-Pointing-Pointer Proof-of-concept results are presented for microfabricated apertures. Black-Right-Pointing-Pointer Charging of such apertures during use remains an experimental challenge.

Soft apertures to shape high-power laser beams

International Nuclear Information System (INIS)

Lukishova, S.G.; Pashinin, P.P.; Batygov, S.K.; Terentiev, B.M.

1989-01-01

Soft or apodized apertures with smooth decreasing from center to edges transmission profiles are used in laser physics for beam shaping. This paper gives the results of the studies of four types of these units for UV, visible and IR lasers. They are made of glasses or crystals with the use of one of the following technologies: absorption induced by ionizing radiation; photodestruction of color centers or photooxidation of impurities ions; additive coloration; frustrated total internal reflection. The special feature of such apertures is their high optical damage resistance under the irradiation of single-pulse laser radiation. They are approximately 3-50 mm in diameter by the methods of making them give the possibility to create near-Gaussian and flat-top beams with dimensions less than 1 mm and larger than 200 mm. The results of using them in high-power single-pulse lasers are presented. Damage thresholds of these apertures in such types of lasers have been defined

Optimized baffle and aperture placement in neutral beamlines

International Nuclear Information System (INIS)

Stone, R.; Duffy, T.; Vetrovec, J.

1983-01-01

Most neutral beamlines contain an iron-core ion-bending magnet that requires shielding between the end of the neutralizer and this magnet. This shielding allows the gas pressure to drop prior to the beam entering the magnet and therefore reduces beam losses in this drift region. We have found that the beam losses can be reduced even further by eliminating the iron-core magnet and the magnetic shielding altogether. The required bending field can be supplied by current coils without the iron poles. In addition, placement of the baffles and apertures can affect the cold gas entering the plasma region and the losses in the neutral beam due to re-ionization. In our study we varied the placement of the baffles, which determine the amount of pumping in each chamber, and the apertures, which determine the beam loss. Our results indicate that a baffle/aperture configuration can be set for either minimum cold gas into the plasma region or minimum beam losses, but not both

Complementary bowtie aperture for localizing and enhancing optical magnetic field

Science.gov (United States)

Zhou, Nan; Kinzel, Edward C.; Xu, Xianfan

2011-08-01

Nanoscale bowtie antenna and bowtie aperture antenna have been shown to generate strongly enhanced and localized electric fields below the diffraction limit in the optical frequency range. According to Babinet's principle, their complements will be efficient for concentrating and enhancing magnetic fields. In this Letter, we discuss the enhancement of magnetic field intensity of nanoscale complementary bowtie aperture as well as complementary bowtie aperture antenna, or diabolo nanoantenna. We show that the complementary bowtie antenna resonates at a smaller wavelength and thus is more suitable for applications near visible wavelengths. The near-field magnetic intensity can be further enhanced by the addition of groove structures that scatter surface plasmon.

Peak stresses shift from femoral tunnel aperture to tibial tunnel aperture in lateral tibial tunnel ACL reconstructions: a 3D graft-bending angle measurement and finite-element analysis.

Science.gov (United States)

Van Der Bracht, Hans; Tampere, Thomas; Beekman, Pieter; Schepens, Alexander; Devriendt, Wouter; Verdonk, Peter; Victor, Jan

2018-02-01

To investigate the effect of tibial tunnel orientation on graft-bending angle and stress distribution in the ACL graft. Eight cadaveric knees were scanned in extension, 45°, 90°, and full flexion. 3D reconstructions with anatomically placed anterior cruciate ligament (ACL) grafts were constructed with Mimics 14.12 ® . 3D graft-bending angles were measured for classic medial tibial tunnels (MTT) and lateral tibial tunnels (LTT) with different drill-guide angles (DGA) (45°, 55°, 65°, and 75°). A pivot shift was performed on 1 knee in a finite-element analysis. The peak stresses in the graft were calculated for eight different tibial tunnel orientations. In a classic anatomical ACL repair, the largest graft-bending angle and peak stresses are seen at the femoral tunnel aperture. The use of a different DGA at the tibial side does not change the graft-bending angle at the femoral side or magnitude of peak stresses significantly. When using LTT, the largest graft-bending angles and peak stresses are seen at the tibial tunnel aperture. In a classic anatomical ACL repair, peak stresses in the ACL graft are found at the femoral tunnel aperture. When an LTT is used, peak stresses are similar compared to classic ACL repairs, but the location of the peak stress will shift from the femoral tunnel aperture towards the tibial tunnel aperture. the risk of graft rupture is similar for both MTTs and LTTs, but the location of graft rupture changes from the femoral tunnel aperture towards the tibial tunnel aperture, respectively. I.

Compromised Photosynthetic Electron Flow And H2O2 Generation Correlate with Genotype-Specific Stomatal Dysfunctions During Resistance Against Powdery Mildew In Oats.

Directory of Open Access Journals (Sweden)

Javier Sánchez-Martín

2016-11-01

Full Text Available Stomatal dysfunction known as locking has been linked to the elicitation of a hypersensitive response (HR following attack of fungal pathogens in cereals. We here assess how spatial and temporal patterns of different resistance mechanisms, such as HR and penetration resistance influence stomatal and photosynthetic parameters in oat (Avena sativa and the possible involvement of hydrogen peroxide (H2O2 in the dysfunctions observed. Four oat cultivars with differential resistance responses (i.e. penetration resistance, early and late HR to powdery mildew (Blumeria graminis f. sp. avenae, Bga were used. Results demonstrated that stomatal dysfunctions were genotype but not response-type dependent since genotypes with similar resistance responses when assessed histologically showed very different locking patterns. Maximum quantum yield (Fv/Fm of photosystem II were compromised in most Bga–oat interactions and photoinhibition increased. However, the extent of the photosynthetic alterations was not directly related to the extent of HR. H2O2 generation is triggered during the execution of resistance responses and can influence stomatal function. Artificially increasing H2O2 by exposing plants to increased light intensity further reduced Fv/Fm ratios and augmented the patterns of stomatal dysfunctions previously observed. The latter results suggest that the observed dysfunctions and hence a cost of resistance may be linked with oxidative stress occurring during defence induced photosynthetic disruption.

Metrology measurements for large-aperture VPH gratings

Science.gov (United States)

Zheng, Jessica R.; Gers, Luke; Heijmans, Jeroen

2013-09-01

The High Efficiency and Resolution Multi Element Spectrograph (HERMES) for the Australian Astronomical Observatory (AAO) uses four large aperture, high angle of incidence volume phase holographic gratings (VPHG) for high resolution `Galactic archaeology' spectroscopy. The large clear aperture, the high diffraction efficiency, the line frequency homogeneity, and mosaic alignment made manufacturing and testing challenging. We developed new metrology systems at the AAO to verify the performance of these VPH gratings. The measured diffraction efficiencies and line frequency of the VPH gratings received so far meet the vendor's provided data. The wavefront quality for the Blue VPH grating is good but the Green and Red VPH gratings need to be post polishing.

An examination of the number of required apertures for step-and-shoot IMRT

International Nuclear Information System (INIS)

Jiang, Z; Earl, M A; Zhang, G W; Yu, C X; Shepard, D M

2005-01-01

We have examined the degree to which step-and-shoot IMRT treatment plans can be simplified (using a small number of apertures) without sacrificing the dosimetric quality of the plans. A key element of this study was the use of direct aperture optimization (DAO), an inverse planning technique where all of the multi-leaf collimator constraints are incorporated into the optimization. For seven cases (1 phantom, 1 prostate, 3 head-and-neck and 2 lung), DAO was used to perform a series of optimizations where the number of apertures per beam direction varied from 1 to 15. In this work, we attempt to provide general guidelines for how many apertures per beam direction are sufficient for various clinical cases using DAO. Analysis of the optimized treatment plans reveals that for most cases, only modest improvements in the objective function and the corresponding DVHs are seen beyond 5 apertures per beam direction. However, for more complex cases, some dosimetric gain can be achieved by increasing the number of apertures per beam direction beyond 5. Even in these cases, however, only modest improvements are observed beyond 9 apertures per beam direction. In our clinical experience, 38 out of the first 40 patients treated using IMRT plans produced using DAO were treated with 9 or fewer apertures per beam direction. The results indicate that many step-and-shoot IMRT treatment plans delivered today are more complex than necessary and can be simplified without sacrificing plan quality

Synthetic Aperture Sequential Beamformation applied to medical imaging

DEFF Research Database (Denmark)

Hemmsen, Martin Christian; Hansen, Jens Munk; Jensen, Jørgen Arendt

2012-01-01

Synthetic Aperture Sequential Beamforming (SASB) is applied to medical ultrasound imaging using a multi element convex array transducer. The main motivation for SASB is to apply synthetic aperture techniques without the need for storing RF-data for a number of elements and hereby devise a system...... with a reduced system complexity. Using a 192 element, 3.5 MHz, λ-pitch transducer, it is demonstrated using tissue-phantom and wire-phantom measurements, how the speckle size and the detail resolution is improved compared to conventional imaging....

Plasticity in stomatal size and density of potato leaves under different irrigation and phosphorus regimes.

Science.gov (United States)

Sun, Yanqi; Yan, Fei; Cui, Xiaoyong; Liu, Fulai

2014-09-01

The morphological features of stomata including their size and density could be modulated by environmental cues; however, the underlying mechanisms remain largely elusive. Here, the effect of different irrigation and phosphorus (P) regimes on stomatal size (SS) and stomatal density (SD) of potato leaves was investigated. The plants were grown in split-root pots under two P fertilization rates (viz., 0 and 100mgkg(-1) soil, denoted as P0 and P1, respectively) and subjected to full (FI), deficit (DI), and partial root-zone drying (PRD) irrigation regimes. Results showed that SS and SD were unresponsive to P but significantly affected by the irrigation treatment. FI plants had the largest SS, followed by DI, and PRD the smallest; and the reverse was the case for SD. Compared to FI and DI, PRD plants had significantly lower values of specific leaf area (SLA) and leaf carbon isotope discrimination (Δ(13)C) under P0. Midday leaf water potential (Ψleaf) and stomatal conductance (gs) was similar for DI and PRD, which was significantly lower than that of FI. Leaf contents of C, N, K, Ca and Mg were higher in PRD than in DI plants, particularly under P0. When analyzed across the three irrigation regimes, it was found that the P1 plants had significantly higher leaf contents of P and Mg, but significantly lower leaf K content compared to the P0 plants. Linear correlation analyses revealed that SS was positively correlated with Ψleaf and Δ(13)C; whereas SD was negatively correlated with Ψleaf, Δ(13)C and SLA, and positively correlated with leaf C, N and Ca contents. And gs was positively correlated with SS but negatively correlated with SD. Collectively, under low P level, the smaller and denser stomata in PRD plants may bring about a more efficient stomatal control over gas exchange, hereby potentially enhance water-use efficiency as exemplified by the lowered leaf Δ(13)C under fluctuating soil moisture conditions. Copyright © 2014 Elsevier GmbH. All rights reserved.

Antimicrobial photodynamic therapy for infectious stomatitis in snakes: Clinical views and microbiological findings.

Science.gov (United States)

Grego, Kathleen Fernandes; Carvalho, Marcelo Pires Nogueira de; Cunha, Marcos Paulo Vieira; Knöbl, Terezinha; Pogliani, Fabio Celidonio; Catão-Dias, José Luiz; Sant'Anna, Sávio Stefanini; Ribeiro, Martha Simões; Sellera, Fábio Parra

2017-12-01

Antimicrobial photodynamic therapy (APDT) has been broadly investigated as an alternative to treat localized infections, without leading to the selection of resistant microorganisms. Infectious stomatitis is a multifactorial disease frequently reported in captive snakes characterized by infection of the oral mucosa and surrounding tissues. In this study, we investigated methylene blue (MB)-mediated APDT to treat infectious stomatitis in snakes and verified the resistance phenotype and genotype before and after APDT. Three Boid snakes presented petechiae, edema and caseous material in their oral cavities. MB (0.01%) was applied on the lesions and after 5min they were irradiated using a red laser (λ=660nm), fluence of 280J/cm 2 , 8J and 80s per point, 100mW, spot size 0.028cm 2 and fluence rate of 3.5W/cm 2 . APDT was repeated once a week during 3 months. Samples of the lesions were collected to identify bacteria and antibiotic resistance profiles. To analyze the clonality of bacterial isolates before and after APDT, isolates were subjected to ERIC PCR analysis. Snakes presented clinical improvement such as reduction of inflammatory signs and caseous material. Pseudomonas aeruginosa and Escherichia coli were present in all snakes; Klebsiella pneumoniae and Morganella morganii were also identified in some animals. We also observed that the oral microbiota was completely replaced following APDT. However, K. pneumoniae isolates before and after APDT were a single clone with 100% of genetic similarity that lost resistance phenotype for seven antibiotics of four classes. These results show that APDT can be used to treat infectious stomatitis in snakes. Copyright © 2017 Elsevier B.V. All rights reserved.

Control of aperture closure during reach-to-grasp movements in parkinson’s disease

Science.gov (United States)

Rand, M. K.; Smiley-Oyen, A. L.; Shimansky, Y. P.; Bloedel, J. R.; Stelmach, G. E.

2007-01-01

This study examined whether the pattern of coordination between arm-reaching toward an object (hand transport) and the initiation of aperture closure for grasping is different between PD patients and healthy individuals, and whether that pattern is affected by the necessity to quickly adjust the reach-to-grasp movement in response to an unexpected shift of target location. Subjects reached for and grasped a vertical dowel, the location of which was indicated by illuminating one of the three dowels placed on a horizontal plane. In control conditions, target location was fixed during the trial. In perturbation conditions, target location was shifted instantaneously by switching the illumination to a different dowel during the reach. The hand distance from the target at which the subject initiated aperture closure (aperture closure distance) was similar for both the control and perturbation conditions within each group of subjects. However, that distance was significantly closer to the target in the PD group than in the control group. The timing of aperture closure initiation varied considerably across the trials in both groups of subjects. In contrast, aperture closure distance was relatively invariant, suggesting that aperture closure initiation was determined by spatial parameters of arm kinematics rather than temporal parameters. The linear regression analysis of aperture closure distance showed that the distance was highly predictable based on the following three parameters: the amplitude of maximum grip aperture, hand velocity, and hand acceleration. This result implies that a control law, the arguments of which include the above parameters, governs the initiation of aperture closure. Further analysis revealed that the control law was very similar between the subject groups under each condition as well as between the control and perturbation conditions for each group. Consequently, the shorter aperture closure distance observed in PD patients apparently is a

Utilization of Dexaltin ointment to radiation stomatitis in patients with cancer of the oral cavity

International Nuclear Information System (INIS)

Ohhashi, Yasushi; Abe, Masaki; Ueda, Noboru

1981-01-01

Dexaltin ointment (sodium polyactylic acid, containing 0.1% dexamethasone) was used to the patients with stomatitis induced by radiotherapy. Fifteen patients with cancer of the oral cavity, aged from 44 to 77, were exposed to 60 Co γ-rays or electron beams, with the irradiation dose of 2400 to 9000 rad. About 60 g of the ointment was pasted for mean period of 6.6 weeks after meals, before sleep, and whenever the patients wanted. Therapeutic effect was observed in every case and in 87% of the case the pain at meals was decreased. The ointment adhered mostly for 1 - 2 hrs and in some cases, more than 3 hrs. No adverse reaction was observed. Therefore it was suggested that Dexaltin was a promising ointment to the radiation stomatitis. (Nakanishi, T.)

Imaging with Synthetic Aperture Radar

CERN Document Server

Massonnet, Didier

2008-01-01

Describing a field that has been transformed by the recent availability of data from a new generation of space and airborne systems, the authors offer a synthetic geometrical approach to the description of synthetic aperture radar, one that addresses physicists, radar specialists, as well as experts in image processing.  

Gamma-aminobutyric acid depletion affects stomata closure and drought tolerance of Arabidopsis thaliana.

Science.gov (United States)

Mekonnen, Dereje Worku; Flügge, Ulf-Ingo; Ludewig, Frank

2016-04-01

A rapid accumulation of γ-aminobutyric acid (GABA) during biotic and abiotic stresses is well documented. However, the specificity of the response and the primary role of GABA under such stress conditions are hardly understood. To address these questions, we investigated the response of the GABA-depleted gad1/2 mutant to drought stress. GABA is primarily synthesized from the decarboxylation of glutamate by glutamate decarboxylase (GAD) which exists in five copies in the genome of Arabidopsis thaliana. However, only GAD1 and GAD2 are abundantly expressed, and knockout of these two copies dramatically reduced the GABA content. Phenotypic analysis revealed a reduced shoot growth of the gad1/2 mutant. Furthermore, the gad1/2 mutant was wilted earlier than the wild type following a prolonged drought stress treatment. The early-wilting phenotype was due to an increase in stomata aperture and a defect in stomata closure. The increase in stomata aperture contributed to higher stomatal conductance. The drought oversensitive phenotype of the gad1/2 mutant was reversed by functional complementation that increases GABA level in leaves. The functionally complemented gad1/2 x pop2 triple mutant contained more GABA than the wild type. Our findings suggest that GABA accumulation during drought is a stress-specific response and its accumulation induces the regulation of stomatal opening thereby prevents loss of water. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Testing of models of stomatal ozone fluxes with field measurements in a mixed Mediterranean forest

Czech Academy of Sciences Publication Activity Database

Fares, S.; Matteucci, G.; Mugnozza, S.; Morani, A.; Calfapietra, Carlo; Salvatori, E.; Fusaro, L.; Manes, F.; Loreto, F.

2013-01-01

Roč. 67, MAR (2013), s. 242-251 ISSN 1352-2310 Institutional support: RVO:67179843 Keywords : Ozone fluxes * Stomatal conductance models * GPP * Mediterranean forest Subject RIV: EH - Ecology, Behaviour Impact factor: 3.062, year: 2013

Large-aperture plasma-assisted deposition of inertial confinement fusion laser coatings.

Science.gov (United States)

Oliver, James B; Kupinski, Pete; Rigatti, Amy L; Schmid, Ansgar W; Lambropoulos, John C; Papernov, Semyon; Kozlov, Alexei; Spaulding, John; Sadowski, Daniel; Chrzan, Z Roman; Hand, Robert D; Gibson, Desmond R; Brinkley, Ian; Placido, Frank

2011-03-20

Plasma-assisted electron-beam evaporation leads to changes in the crystallinity, density, and stresses of thin films. A dual-source plasma system provides stress control of large-aperture, high-fluence coatings used in vacuum for substrates 1m in aperture.

Deliverable navigation for multicriteria IMRT treatment planning by combining shared and individual apertures

International Nuclear Information System (INIS)

Fredriksson, Albin; Bokrantz, Rasmus

2013-01-01

We consider the problem of deliverable Pareto surface navigation for step-and-shoot intensity-modulated radiation therapy. This problem amounts to calculation of a collection of treatment plans with the property that convex combinations of plans are directly deliverable. Previous methods for deliverable navigation impose restrictions on the number of apertures of the individual plans, or require that all treatment plans have identical apertures. We introduce simultaneous direct step-and-shoot optimization of multiple plans subject to constraints that some of the apertures must be identical across all plans. This method generalizes previous methods for deliverable navigation to allow for treatment plans with some apertures from a collective pool and some apertures that are individual. The method can also be used as a post-processing step to previous methods for deliverable navigation in order to improve upon their plans. By applying the method to subsets of plans in the collection representing the Pareto set, we show how it can enable convergence toward the unrestricted (non-navigable) Pareto set where all apertures are individual. (paper)

A novel approach to correct the coded aperture misalignment for fast neutron imaging

Energy Technology Data Exchange (ETDEWEB)

Zhang, F. N.; Hu, H. S., E-mail: huasi-hu@mail.xjtu.edu.cn; Wang, D. M.; Jia, J. [School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Zhang, T. K. [Laser Fusion Research Center, CAEP, Mianyang, 621900 Sichuan (China); Jia, Q. G. [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China)

2015-12-15

Aperture alignment is crucial for the diagnosis of neutron imaging because it has significant impact on the coding imaging and the understanding of the neutron source. In our previous studies on the neutron imaging system with coded aperture for large field of view, “residual watermark,” certain extra information that overlies reconstructed image and has nothing to do with the source is discovered if the peak normalization is employed in genetic algorithms (GA) to reconstruct the source image. Some studies on basic properties of residual watermark indicate that the residual watermark can characterize coded aperture and can thus be used to determine the location of coded aperture relative to the system axis. In this paper, we have further analyzed the essential conditions for the existence of residual watermark and the requirements of the reconstruction algorithm for the emergence of residual watermark. A gamma coded imaging experiment has been performed to verify the existence of residual watermark. Based on the residual watermark, a correction method for the aperture misalignment has been studied. A multiple linear regression model of the position of coded aperture axis, the position of residual watermark center, and the gray barycenter of neutron source with twenty training samples has been set up. Using the regression model and verification samples, we have found the position of the coded aperture axis relative to the system axis with an accuracy of approximately 20 μm. Conclusively, a novel approach has been established to correct the coded aperture misalignment for fast neutron coded imaging.

Effects of surface-mapping corrections and synthetic-aperture focusing techniques on ultrasonic imaging

International Nuclear Information System (INIS)

Barna, B.A.; Johnson, J.A.

1981-01-01

Improvements in ultrasonic imaging that can be obtained using algorithms that map the surface of targets are evaluated. This information is incorporated in the application of synthetic-aperture focusing techniques which also have the potential to improve image resolution. Images obtained using directed-beam (flat) transducers and the focused transducers normally used for synthetic-aperture processing are quantitatively compared by using no processing, synthetic-aperture processing with no corrections for surface variations, and synthetic-aperture processing with surface mapping. The unprocessed images have relatively poor lateral resolutions because echoes from two adjacent reflectors show interference effects which prevent their identification even if the spacing is larger than the single-hole resolution. The synthetic-aperture-processed images show at least a twofold improvement in lateral resolution and greatly reduced interference effects in multiple-hole images compared to directed-beam images. Perhaps more importantly, in images of test blocks with substantial surface variations portions of the image are displaced from their actual positions by several wavelengths. To correct for this effect an algorithm has been developed for calculating the surface variations. The corrected images produced using this algorithm are accurate within the experimental error. In addition, the same algorithm, when applied to the directed-beam data, produced images that are not only accurately positioned, but that also have a resolution comparable to conventional synthetic-aperture-processed images obtained from focused-transducer data. This suggests that using synthetic-aperture processing on the type of data normally collected during directed-beam ultrasonic inspections would eliminate the need to rescan for synthetic-aperture enhancement

Leaf temperature and stomatal influences on sap velocity diurnal hysteresis in the Amazon rainforest

Science.gov (United States)

Jardine, K.; Gimenez, B.; Negron Juarez, R. I.; Koven, C.; Powell, T.; Higuchi, N.; Chambers, J.; Varadharajan, C.

2016-12-01

In order to improve our ability to predict terrestrial evapotranspiration fluxes, an understanding of the interactions between plant physiology and environmental conditions is necessary, but remains poorly characterized, especially in tropical ecosystems. In this study we show a tight positive correlation between sap velocity (at 1 m of height) and leaf surface temperature (LST, 20-30 m of height) in canopy dominant trees in two primary rainforest sites in the Amazon basin (Santarém and Manaus, Brazil). As leaf temperatures varied throughout the day, sap velocity responded with little delay (<15 min). Positive sap velocity was often observed at night, but also closely followed night time LSTs. When plotted versus LST, sap velocity showed an exponential increase before reaching a reflection point and a plateau and is characterized as a sigmoidal curve, in all observed trees. Moreover, a clear diurnal hysteresis in sap velocity was evident with morning periods showing higher temperature sensitivities than afternoon and night periods. Diurnal leaf observations showed a morning peak in stomatal conductance ( 10:00-10:30), but a mid-day to afternoon peak in transpiration and leaf temperature (12:00-14:00). Our observations suggest the sap velocity-LST hysteresis pattern arises due to the temporal offset between stomatal conductance and vapor pressure deficits (VPD) and demonstrates the dominating effect of VPD over stomatal conductance in maintaining high transpiration/sap flow rates under elevated temperatures. Our results have important implications for modeling tropical forest transpiration and suggests the possibility of predicting evapotranspiration fluxes at the ecosystem to regional scales based on remote sensed vegetation temperature.

Class of near-perfect coded apertures

International Nuclear Information System (INIS)

Cannon, T.M.; Fenimore, E.E.

1977-01-01

Coded aperture imaging of gamma ray sources has long promised an improvement in the sensitivity of various detector systems. The promise has remained largely unfulfilled, however, for either one of two reasons. First, the encoding/decoding method produces artifacts, which even in the absence of quantum noise, restrict the quality of the reconstructed image. This is true of most correlation-type methods. Second, if the decoding procedure is of the deconvolution variety, small terms in the transfer function of the aperture can lead to excessive noise in the reconstructed image. It is proposed to circumvent both of these problems by use of a uniformly redundant array (URA) as the coded aperture in conjunction with a special correlation decoding method. It is shown that the reconstructed image in the URA system contains virtually uniform noise regardless of the structure in the original source. Therefore, the improvement over a single pinhole camera will be relatively larger for the brighter points in the source than for the low intensity points. In the case of a large detector background noise the URA will always do much better than the single pinhole regardless of the structure of the object. In the case of a low detector background noise, the improvement of the URA over the single pinhole will have a lower limit of approximately (1/2f)/sup 1 / 2 / where f is the fraction of the field of view which is uniformly filled by the object

Forensic Facial Reconstruction: Relationship Between the Alar Cartilage and Piriform Aperture.

Science.gov (United States)

Strapasson, Raíssa Ananda Paim; Herrera, Lara Maria; Melani, Rodolfo Francisco Haltenhoff

2017-11-01

During forensic facial reconstruction, facial features may be predicted based on the parameters of the skull. This study evaluated the relationships between alar cartilage and piriform aperture and nose morphology and facial typology. Ninety-six cone beam computed tomography images of Brazilian subjects (49 males and 47 females) were used in this study. OsiriX software was used to perform the following measurements: nasal width, distance between alar base insertion points, lower width of the piriform aperture, and upper width of the piriform aperture. Nasal width was associated with the lower width of the piriform aperture, sex, skeletal vertical pattern of the face, and age. The current study contributes to the improvement of forensic facial guides by identifying the relationships between the alar cartilages and characteristics of the biological profile of members of a population that has been little studied thus far. © 2017 American Academy of Forensic Sciences.

Gaseous NO2 effects on stomatal behavior, photosynthesis and respiration of hybrid poplar leaves

Science.gov (United States)

In this study, we used poplar as a model plant and investigated the effects of gaseous nitrogen dioxide (NO2, 4 microliter per liter) on stomatal conductance, photosynthesis, dark- and photorespiration of Populus alba x Populus berolinensis hybrid leaves using the photosynthesis system and scanning...

Design of a neutron penumbral-aperture microscope with 10-μm resolution

International Nuclear Information System (INIS)

Ress, D.; Lerche, R.A.; Ellis, R.J.; Lane, S.M.

1990-05-01

We are currently designing a 10-μm resolution neutron penumbral-aperture microscope to diagnose high-convergence targets at the Nova laser facility. To achieve such high resolution, the new microscope will require substantial improvements in three areas. First, we have designed thick penumbral apertures with extremely sharp cutoffs over a useful (∼100 μm) field of view; fabrication of such apertures appears feasible using gold electroplating techniques. Second, the limited field of view and required close proximity of the aperture to the target (2 cm) necessitates a durable mounting and alignment system with +25 μm accuracy. Finally, a neutron detector containing 160,000 scintillator elements is required; readout and optimization of this large array are outstanding issues. 5 refs., 3 figs

Method and apparatus for shadow aperture backscatter radiography (SABR) system and protocol

Science.gov (United States)

Shedlock, Daniel (Inventor); Jacobs, Alan M. (Inventor); Jacobs, Sharon Auerback (Inventor); Dugan, Edward (Inventor)

2010-01-01

A shadow aperture backscatter radiography (SABR) system includes at least one penetrating radiation source for providing a penetrating radiation field, and at least one partially transmissive radiation detector, wherein the partially transmissive radiation detector is interposed between an object region to be interrogated and the radiation source. The partially transmissive radiation detector transmits a portion of the illumination radiation field. A shadow aperture having a plurality of radiation attenuating regions having apertures therebetween is disposed between the radiation source and the detector. The apertures provide illumination regions for the illumination radiation field to reach the object region, wherein backscattered radiation from the object is detected and generates an image by the detector in regions of the detector that are shadowed by the radiation attenuation regions.

Stomatal- and growth responses in willow to deficits in water- and nitrogen supply. Final report

Energy Technology Data Exchange (ETDEWEB)

Stadenberg, I. [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dep. for Production Ecology

2002-02-01

The two plants, grown with an [N] of 100 mg per litre and subjected to a decrease in N-supply decreased their leaf relative growth rate from 22% per day to 13% per day within 2 days. Stomatal conductance did not change significantly after the decrease in N-supply. Xylem samples did not show any significant changes in its composition of mineral nutrient elements after decreased N-supply. The three plants, grown with an [N] of 50 mg per litre and subjected to a decrease in N-supply, significantly decreased leaf relative growth rate from 18.5 % to 9 % per day within 2 days. Stomatal conductance did not change significantly after the decrease in N-supply. Xylem sap samples showed a significant decrease in [K] (74 mg/l to 42 mg/l) and [S] (11 mg/l to 3.2 mg/l) within 2 days after decreased N-supply. The four plants subjected to root drying decreased their leaf relative growth rate slightly but not significantly during the drying period. Xylem samples showed a significant decrease in S-concentration (11 mg/l to 1.3 mg/l) and [NO{sub 3}] (8.0 mg/l to 1.0 mg/l), while [Fe] increased significantly (0.065 mg/l to 0.14 mg/l). Stomatal conductance is known to decrease when plants are subjected to drying of part of the root system. This was shown for Salix dasyclados in a recent publication.

Serum cytokine profile and clinicopathological findings in oral lichen planus, oral lichenoid lesions and stomatitis

Science.gov (United States)

Johansen, Jeanne Duus; Reibel, Jesper; Zachariae, Claus; Pedersen, Anne Marie Lynge

2017-01-01

Abstract The objective of this study was to examine if clinical and histopathological variables in patients with oral lichen planus (OLP), oral lichenoid lesions (OLL), and generalized stomatitis display different cytokine profiles and if concomitant contact allergy influences this profile. Forty‐nine patients and 29 healthy age‐ and gender‐matched subjects were included. Demographic and clinical data immunohistochemical findings in mucosal specimens, results of contact allergy testing, and serum levels of tumor necrosis factor‐α, interferon‐γ, interleukin (IL)‐6, IL‐10, IL‐12p40, and IL‐12p70 were analyzed and compared between groups. Nineteen patients had OLP, primarily with ulcerative lesions on the buccal mucosa, 19 patients had OLL, and 11 patients had generalized stomatitis. All patients had oral symptoms, mainly stinging and burning. Nineteen patients and 10 healthy subjects had contact allergies, primarily to fragrance ingredients. Patient groups did not differ with regard to oral symptoms, clinical pattern of the lesions, or contact allergy. Serum cytokine levels did not differ between the different patient groups and were not related to histopathological findings. The patients had higher levels of IL‐6 than the healthy subjects. Interferon‐γ, IL‐12p40, and IL‐12p70 were below detection limit. Our findings indicate that OLP, OLL, and generalized stomatitis cannot be discriminated by means of the selected serum cytokines, and that the presence of concomitant contact allergy does not influence the cytokine expression. PMID:29744205

High-dynamic range compressive spectral imaging by grayscale coded aperture adaptive filtering

Directory of Open Access Journals (Sweden)

Nelson Eduardo Diaz

2015-09-01

Full Text Available The coded aperture snapshot spectral imaging system (CASSI is an imaging architecture which senses the three dimensional informa-tion of a scene with two dimensional (2D focal plane array (FPA coded projection measurements. A reconstruction algorithm takes advantage of the compressive measurements sparsity to recover the underlying 3D data cube. Traditionally, CASSI uses block-un-block coded apertures (BCA to spatially modulate the light. In CASSI the quality of the reconstructed images depends on the design of these coded apertures and the FPA dynamic range. This work presents a new CASSI architecture based on grayscaled coded apertu-res (GCA which reduce the FPA saturation and increase the dynamic range of the reconstructed images. The set of GCA is calculated in a real-time adaptive manner exploiting the information from the FPA compressive measurements. Extensive simulations show the attained improvement in the quality of the reconstructed images when GCA are employed.  In addition, a comparison between traditional coded apertures and GCA is realized with respect to noise tolerance.

A method to select aperture margin in collimated spot scanning proton therapy

International Nuclear Information System (INIS)

Wang, Dongxu; Smith, Blake R; Gelover, Edgar; Flynn, Ryan T; Hyer, Daniel E

2015-01-01

The use of collimator or aperture may sharpen the lateral dose gradient for spot scanning proton therapy. However, to date, there has not been a standard method to determine the aperture margin for a single field in collimated spot scanning proton therapy. This study describes a theoretical framework to select the optimal aperture margin for a single field, and also presents the spot spacing limit required such that the optimal aperture margin exists. Since, for a proton pencil beam partially intercepted by collimator, the maximum point dose (spot center) shifts away from the original pencil beam central axis, we propose that the optimal margin should be equal to the maximum pencil beam center shift under the condition that spot spacing is small with respect to the maximum pencil beam center shift, which can be numerically determined based on beam modeling data. A test case is presented which demonstrates agreement with the prediction made based on the proposed methods. When apertures are applied in a commercial treatment planning system this method may be implemented. (note)

Detecting the differences in responses of stomatal conductance to moisture stresses between deciduous shrubs and Artemisia subshrubs.

Science.gov (United States)

Gao, Qiong; Yu, Mei; Zhou, Chan

2013-01-01

Shrubs and subshrubs can tolerate wider ranges of moisture stresses in both soil and air than other plant life forms, and thus represent greater nonlinearity and uncertainty in ecosystem physiology. The objectives of this paper are to model shrub/subshrub stomatal conductance by synthesizing the field leaf gas exchanges data of 24 species in China, in order to detect the differences between deciduous shrubs and Artemisia subshrubs in their responses of stomatal conductance to changes in the moisture stresses. We revised a model of stomatal conductance by incorporating the tradeoff between xylem hydraulic efficiency and cavitation loss risk. We then fit the model at the three hierarchical levels: global (pooling all data as a single group), three functional groups (deciduous non-legume shrubs, deciduous legume shrubs, and subshrubs in Artemisia genus), and individual observations (species × sites). Bayesian inference with Markov Chain Monte Carlo method was applied to obtain the model parameters at the three levels. We found that the model at the level of functional groups is a significant improvement over that at the global level, indicating the significant differences in the stomatal behavior among the three functional groups. The differences in tolerance and sensitivities to changes in moisture stresses are the most evident between the shrubs and the subshrubs: The two shrub groups can tolerate much higher soil water stress than the subshrubs. The analysis at the observation level is also a significant improvement over that at the functional group level, indicating great variations within each group. Our analysis offered a clue for the equivocal issue of shrub encroachment into grasslands: While the invasion by the shrubs may be irreversible, the dominance of subshrubs, due to their lower resistance and tolerance to moisture stresses, may be put down by appropriate grassland management.

The role of the plasma membrane H+-ATPase in plant-microbe interactions.

Science.gov (United States)

Elmore, James Mitch; Coaker, Gitta

2011-05-01

Plasma membrane (PM) H+-ATPases are the primary pumps responsible for the establishment of cellular membrane potential in plants. In addition to regulating basic aspects of plant cell function, these enzymes contribute to signaling events in response to diverse environmental stimuli. Here, we focus on the roles of the PM H+-ATPase during plant-pathogen interactions. PM H+-ATPases are dynamically regulated during plant immune responses and recent quantitative proteomics studies suggest complex spatial and temporal modulation of PM H+-ATPase activity during early pathogen recognition events. Additional data indicate that PM H+-ATPases cooperate with the plant immune signaling protein RIN4 to regulate stomatal apertures during bacterial invasion of leaf tissue. Furthermore, pathogens have evolved mechanisms to manipulate PM H+-ATPase activity during infection. Thus, these ubiquitous plant enzymes contribute to plant immune responses and are targeted by pathogens to increase plant susceptibility.

Use of sap flow measurements to validate stomatal functions for mature beech (Fagus sylvatica) in view of ozone uptake calculations

International Nuclear Information System (INIS)

Braun, Sabine; Schindler, Christian; Leuzinger, Sebastian

2010-01-01

For a quantitative estimate of the ozone effect on vegetation reliable models for ozone uptake through the stomata are needed. Because of the analogy of ozone uptake and transpiration it is possible to utilize measurements of water loss such as sap flow for quantification of ozone uptake. This technique was applied in three beech (Fagus sylvatica) stands in Switzerland. A canopy conductance was calculated from sap flow velocity and normalized to values between 0 and 1. It represents mainly stomatal conductance as the boundary layer resistance in forests is usually small. Based on this relative conductance, stomatal functions to describe the dependence on light, temperature, vapour pressure deficit and soil moisture were derived using multivariate nonlinear regression. These functions were validated by comparison with conductance values directly estimated from sap flow. The results corroborate the current flux parameterization for beech used in the DO 3 SE model. - A method was developed to derive stomatal functions and ozone uptake calculation from sap flow.

Digital filtering and reconstruction of coded aperture images

International Nuclear Information System (INIS)

Tobin, K.W. Jr.

1987-01-01

The real-time neutron radiography facility at the University of Virginia has been used for both transmission radiography and computed tomography. Recently, a coded aperture system has been developed to permit the extraction of three dimensional information from a low intensity field of radiation scattered by an extended object. Short wave-length radiations (e.g. neutrons) are not easily image because of the difficulties in achieving diffraction and refraction with a conventional lens imaging system. By using a coded aperture approach, an imaging system has been developed that records and reconstructs an object from an intensity distribution. This system has a signal-to-noise ratio that is proportional to the total open area of the aperture making it ideal for imaging with a limiting intensity radiation field. The main goal of this research was to develope and implement the digital methods and theory necessary for the reconstruction process. Several real-time video systems, attached to an Intellect-100 image processor, a DEC PDP-11 micro-computer, and a Convex-1 parallel processing mainframe were employed. This system, coupled with theoretical extensions and improvements, allowed for retrieval of information previously unobtainable by earlier optical methods. The effect of thermal noise, shot noise, and aperture related artifacts were examined so that new digital filtering techniques could be constructed and implemented. Results of image data filtering prior to and following the reconstruction process are reported. Improvements related to the different signal processing methods are emphasized. The application and advantages of this imaging technique to the field of non-destructive testing are also discussed

Strategies used to walk through a moving aperture.

Science.gov (United States)

Cinelli, Michael E; Patla, Aftab E; Allard, Fran

2008-05-01

The objectives of the study were to determine what strategy (pursuit or interception) individuals used to pass through an oscillating target and to determine if individuals walked towards where they were looking. Kinematic and gaze behaviour data was collected from seven healthy female participants as they started at one of five different starting positions and walked 7 m towards an oscillating target. The target was a two-dimensional 70 cm aperture made by two-76 cm wide doors and oscillated between two end posts that were 300 cm apart. In order to quantify the objectives, target-heading angles [Fajen BR, Warren WH. Behavioral dynamics of steering, obstacle avoidance, and route selection. J Exp Psychol Hum Percept Perform 2003;29(2):343-62; Fajen BR, Warren WH. Visual guidance of intercepting a moving target on foot. Perception 2004;33:689-715] were calculated. Results showed that the participants used neither an interception nor a pursuit strategy to successfully pass through the moving aperture. The participants steered towards the middle of the pathway prior to passing through the middle of the aperture. A cross correlation between the horizontal gaze locations and the medial/lateral (M/L) location of the participants' center of mass (COM) was performed. The results from the cross correlation show that during the final 2s prior to crossing the aperture, the participants walked where they were looking. The findings from this study suggest that individuals simplify a task by decreasing the perceptual load until the final stages. In this way the final stages of this task were visually driven.

Scaling Laws for Dynamic Aperture due to Chromatic Sextupoles

CERN Document Server

Scandale, Walter

1997-01-01

Scaling laws for the dynamic aperture due to chromatic sextupoles are investigated. The problem is addressed in a simplified lattice model containing 4 N identical cells and one linear betatron phase shifter to break the overall cell-lattice symmetry. Two families of chromatic sextupoles are used to compensate the natural chromaticity. Analytical formulae for the dynamic apertur as a function of the number of cells and of the cell length are found and confirmed through computer tracking.

Phase Centers of Subapertures in a Tapered Aperture Array.

Energy Technology Data Exchange (ETDEWEB)

Doerry, Armin W. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Bickel, Douglas L. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

2015-11-01

Antenna apertures that are tapered for sidelobe control can also be parsed into subapertures for Direction of Arrival (DOA) measurements. However, the aperture tapering complicates phase center location for the subapertures, knowledge of which is critical for proper DOA calculation. In addition, tapering affects subaperture gains, making gain dependent on subaperture position. Techniques are presented to calculate subaperture phase center locations, and algorithms are given for equalizing subapertures’ gains. Sidelobe characteristics and mitigation are also discussed.

MEGARA Optics: Sub-aperture Stitching Interferometry for Large Surfaces

Science.gov (United States)

Aguirre-Aguirre, Daniel; Carrasco, Esperanza; Izazaga-Pérez, Rafael; Páez, Gonzalo; Granados-Agustín, Fermín; Percino-Zacarías, Elizabeth; Gil de Paz, Armando; Gallego, Jesús; Iglesias-Páramo, Jorge; Villalobos-Mendoza, Brenda

2018-04-01

In this work, we present a detailed analysis of sub-aperture interferogram stitching software to test circular and elliptical clear apertures with diameters and long axes up to 272 and 180 mm, respectively, from the Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía (MEGARA). MEGARA is a new spectrograph for the Gran Telescopio Canarias (GTC). It offers a resolution between 6000 and 20000 via the use of volume phase holographic gratings. It has an integral field unit and a set of robots for multi-object spectroscopy at the telescope focal plane. The output end of the fibers forms the spectrograph pseudo-slit. The fixed geometry of the collimator and camera configuration requires prisms in addition to the flat windows of the volume phase holographic gratings. There are 73 optical elements of large aperture and high precision manufactured in Mexico at the Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE) and the Centro de Investigaciones en Óptica (CIO). The principle of stitching interferometry is to divide the surface being tested into overlapping small sections, which allows an easier analysis (Kim & Wyant 1981). This capability is ideal for non-contact tests for unique and large optics as required by astronomical instruments. We show that the results obtained with our sub-aperture stitching algorithm were consistent with other methods that analyze the entire aperture. We used this method to analyze the 24 MEGARA prisms that could not be tested otherwise. The instrument has been successfully commissioned at GTC in all the spectral configurations. The fulfillment of the irregularity specifications was one of the necessary conditions to comply with the spectral requirements.

Maximum leaf conductance driven by CO2 effects on stomatal size and density over geologic time.

Science.gov (United States)

Franks, Peter J; Beerling, David J

2009-06-23

Stomatal pores are microscopic structures on the epidermis of leaves formed by 2 specialized guard cells that control the exchange of water vapor and CO(2) between plants and the atmosphere. Stomatal size (S) and density (D) determine maximum leaf diffusive (stomatal) conductance of CO(2) (g(c(max))) to sites of assimilation. Although large variations in D observed in the fossil record have been correlated with atmospheric CO(2), the crucial significance of similarly large variations in S has been overlooked. Here, we use physical diffusion theory to explain why large changes in S necessarily accompanied the changes in D and atmospheric CO(2) over the last 400 million years. In particular, we show that high densities of small stomata are the only way to attain the highest g(cmax) values required to counter CO(2)"starvation" at low atmospheric CO(2) concentrations. This explains cycles of increasing D and decreasing S evident in the fossil history of stomata under the CO(2) impoverished atmospheres of the Permo-Carboniferous and Cenozoic glaciations. The pattern was reversed under rising atmospheric CO(2) regimes. Selection for small S was crucial for attaining high g(cmax) under falling atmospheric CO(2) and, therefore, may represent a mechanism linking CO(2) and the increasing gas-exchange capacity of land plants over geologic time.

Apparatus and method for deterministic control of surface figure during full aperture polishing

Science.gov (United States)

Suratwala, Tayyab Ishaq; Feit, Michael Dennis; Steele, William Augustus

2013-11-19

A polishing system configured to polish a lap includes a lap configured to contact a workpiece for polishing the workpiece; and a septum configured to contact the lap. The septum has an aperture formed therein. The radius of the aperture and radius the workpiece are substantially the same. The aperture and the workpiece have centers disposed at substantially the same radial distance from a center of the lap. The aperture is disposed along a first radial direction from the center of the lap, and the workpiece is disposed along a second radial direction from the center of the lap. The first and second radial directions may be opposite directions.

In Vivo Real Time Volumetric Synthetic Aperture Ultrasound Imaging

DEFF Research Database (Denmark)

Bouzari, Hamed; Rasmussen, Morten Fischer; Brandt, Andreas Hjelm

2015-01-01

Synthetic aperture (SA) imaging can be used to achieve real-time volumetric ultrasound imaging using 2-D array transducers. The sensitivity of SA imaging is improved by maximizing the acoustic output, but one must consider the limitations of an ultrasound system, both technical and biological....... This paper investigates the in vivo applicability and sensitivity of volumetric SA imaging. Utilizing the transmit events to generate a set of virtual point sources, a frame rate of 25 Hz for a 90° x 90° field-of-view was achieved. Data were obtained using a 3.5 MHz 32 x 32 elements 2-D phased array...... transducer connected to the experimental scanner (SARUS). Proper scaling is applied to the excitation signal such that intensity levels are in compliance with the U.S. Food and Drug Administration regulations for in vivo ultrasound imaging. The measured Mechanical Index and spatial-peak- temporal...

Brief oral cryotherapy for the prevention of high-dose melphalan-induced stomatitis in allogeneic hematopoietic stem cell transplant recipients.

Science.gov (United States)

Mori, Takehiko; Yamazaki, Rie; Aisa, Yoshinobu; Nakazato, Tomonori; Kudo, Masumi; Yashima, Tomoko; Kondo, Sakiko; Ikeda, Yasuo; Okamoto, Shinichiro

2006-04-01

We previously reported the efficacy of oral cryotherapy for the prevention of high-dose melphalan-induced stomatitis. The purpose of this study was to evaluate whether the further shortening of the duration of oral cryotherapy could minimize its side effects while sparing its efficacy. Seventeen consecutive recipients of allogeneic hematopoieic stem cell transplant conditioned with high-dose melphalan in combination with fludarabine alone or with fludarabine and additional radiation were enrolled in the study. The severity of stomatitis was graded according to the National Cancer Institute-Common Toxicity Criteria. Patients were kept on oral cryotherapy shortly before, during, and for additional 30 min after the completion of melphalan administration (60-min oral cryotherapy). Patients who were also enrolled in our previous study received the same type of oral cryotherapy but for additional 90 min after the completion of melphalan administration (120-min oral cryotherapy), and they served as controls. Only 2 (11.8%) of 17 patients receiving 60-min oral cryotherapy and 2 (11.1%) of 18 patients receiving 120-min oral cryotherapy developed grade 2 or 3 stomatitis, respectively. The difference between groups was not statistically significant (P = 0.677). The incidence of unpleasant symptoms such as chills and nausea during oral cryotherapy decreased significantly with 60-min oral cryotherapy, as compared with that associated with 120-min oral cryotherapy (P cryotherapy is as effective as 120-min oral cryotherapy at preventing high-dose melphalan-induced stomatitis, and shorter treatment might have contributed to relieve patient discomfort during oral cryotherapy.

Investigation of novel fractal shape of the nano-aperture as a metasurface for bio sensing application

Energy Technology Data Exchange (ETDEWEB)

Heydari, Samaneh [Sama Technical and Vocational Training College, Islamic Azad University, Isfahan Branch, Khorasgan (Iran, Islamic Republic of); Rastan, Iman; Parvin, Amin [Faculty of Eng., Science and Research Branch, Islamic Azad University, Shiraz (Iran, Islamic Republic of); Pirooj, Azadeh [Faculty of Eng., Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Zarrabi, Ferdows B., E-mail: ferdows.zarrabi@yahoo.com [Young Researchers and Elite Club, Babol Branch, Islamic Azad University, Babol (Iran, Islamic Republic of)

2017-01-23

Recently, nano-aperture is noticed due to its good transmission in the optical regime. Also, the nano-apertures are developed at the metasurface design for circular polarization; for this aim, various shapes of the nano-aperture are suggested. To reach this objective, we have developed a novel Jerusalem cross fractal shape for a mid-infrared application. We have simulated various formations of the nano-fractal Jerusalem cross based on a simple cross to show the effect of nano-aperture shape on electrical field enhancement in the near-field which is important in spectroscopy and optical imaging. In addition, we have used a single layer graphene over the aperture as a coat for making reconfigurable characteristic also creating a membrane for placement of nano-particle over the aperture. Implementation of the graphene is an amendment to the transfer of the nano-apertures. The biological materials with a thickness of 80 nm have been placed over the graphene layer and the Figures of Merits (FOM) have been obtained. Additionally, the prototype of nano-antenna is independent from incident wave polarization. The Finite Difference Time Domain (FDTD) calculations have been implemented in the simulation and modeling the nano-apertures. - Highlights: • Nano-apertures are developed at the metasurface design for circular polarization. • We have developed a novel Jerusalem cross fractal shape for a mid-infrared application. • Effect of nano-aperture shape on near-field enhancement is noticed which is important in spectroscopy and optical imaging. • Single layer graphene over the aperture as a coat for making reconfigurable characteristic.

Optimization of Synthetic Aperture Image Quality

DEFF Research Database (Denmark)

Moshavegh, Ramin; Jensen, Jonas; Villagómez Hoyos, Carlos Armando

2016-01-01

Synthetic Aperture (SA) imaging produces high-quality images and velocity estimates of both slow and fast flow at high frame rates. However, grating lobe artifacts can appear both in transmission and reception. These affect the image quality and the frame rate. Therefore optimization of parameter...

Synthetic Aperture Beamformation using the GPU

DEFF Research Database (Denmark)

Hansen, Jens Munk; Schaa, Dana; Jensen, Jørgen Arendt

2011-01-01

A synthetic aperture ultrasound beamformer is implemented for a GPU using the OpenCL framework. The implementation supports beamformation of either RF signals or complex baseband signals. Transmit and receive apodization can be either parametric or dynamic using a fixed F-number, a reference...

First Beam Based Aperture Measurements in the Arcs of the CERN Large Hadron Collider

CERN Document Server

Redaelli, S; Calaga, R; Dehning, B; Giovannozzi, M; Roncarolo, F; Tomás, R

2010-01-01

The LHC injection tests performed in August and early September 2008 in preparation for the circulating beam operation provided the first opportunity to measure with beam the mechanical aperture in two LHC sectors (2-3 and 7- 8). The aperture was probed by exciting free oscillations and local orbit bumps of the injected beam trajectories. Intensities of a few 109 protons were used to remain safely below the quench limit of superconductingmagnets in case of beam losses. The methods used to measure the mechanical aperture, the available on-line tools, and beam measurements for both sectors are presented. Detailed comparisons with the expected results from the as-built aperture models are also presented. It is shown that the measurements results are in good agreement with the LHC design aperture.

Hydrocephalus secondary to obstruction of the lateral apertures in two dogs.

Science.gov (United States)

Kent, M; Glass, E N; Haley, A C; Shaikh, L S; Sequel, M; Blas-Machado, U; Bishop, T M; Holmes, S P; Platt, S R

2016-11-01

Traditionally, hydrocephalus is divided into communicating or non-communicating (obstructive) based on the identification of a blockage of cerebrospinal fluid (CSF) flow through the ventricular system. Hydrocephalus ex vacuo refers to ventricular enlargement as a consequence of neuroparenchymal loss. Hydrocephalus related to obstruction of the lateral apertures of the fourth ventricles has rarely been described. The clinicopathologic findings in two dogs with hydrocephalus secondary to obstruction of the lateral apertures of the fourth ventricle are reported. Signs were associated with a caudal cervical spinal cord lesion in one dog and a caudal brain stem lesion in the other dog. Magnetic resonance imaging (MRI) disclosed dilation of the ventricular system, including the lateral recesses of the fourth ventricle. In one dog, postmortem ventriculography confirmed obstruction of the lateral apertures. Microscopic changes were identified in the choroid plexus in both dogs, yet a definitive cause of the obstructions was not identified. The MRI findings in both dogs are similar to membranous occlusion of the lateral and median apertures in human patients. MRI detection of dilation of the entire ventricular system in the absence of an identifiable cause should prompt consideration of an obstruction of the lateral apertures. In future cases, therapeutic interventions aimed at re-establishing CSF flow or ventriculoperitoneal catheterisation should be considered. © 2016 Australian Veterinary Association.

Dynamic aperture ampersand extraction studies for the SSC High-Energy Booster

International Nuclear Information System (INIS)

Chao, A.W.; Dutt, S.K.; Johnson, D.E.; Sen, T.; Yan, Y.

1990-09-01

The final booster in the injector chain for the Superconducting Super Collider is a machine approximately twice the size of the Tevatron. Its design includes approximately 450, 15+ m superconducting dipoles. The original designs specified dipoles with a 7 cm coil-winding diameter and an inner horizontal beam-pipe aperture of 55 mm. This dipole design was chosen in order to provide an adequately large good-field aperture for both the beam injection process and for the slow-extraction of high-energy test beams. With the recent decision to increase the Collider dipole coil-winding diameter to 5 cm, the question of the needed HEB aperture was raised. An argument for dipole commonality between the HEB and Collider was developed, and a preliminary examination of a 5 cm HEB dipole was undertaken. This paper reports the results of a detailed study of the injection dynamic aperture for magnet errors corresponding to both a 5 cm and 7 cm dipole. Also studied and reported are preliminary results of the resonant-extraction process for the two magnet designs in question. These studies are in the form of multiparticle computer simulations. The results of the studies indicate that the 7 cm dipole design is consistent with the desired performance requirements for the HEB, while the 5 cm dipole design is marginal. We have not studied intermediate aperture values. 8 refs., 11 figs

Quantitative Estimation of Yeast on Maxillary Denture in Patients with Denture Stomatitis and the Effect of Chlorhexidine Gluconate in Reduction of Yeast

Directory of Open Access Journals (Sweden)

Jaykumar R Gade

2011-01-01

Full Text Available Denture stomatitis is a condition associated with wearing of a denture. The predisposing factor leading to denture stomatitis could be poor oral hygiene, ill-fitting denture and relief areas. Around 30 patients with denture stomatitis were advised to rinse with chlorhexidine gluconate mouthwash for 14 days and were directed to immerse the upper denture in the chlorhexidine solution for 8 hours. The samples were collected by scraping maxillary denture in saline at three intervals, prior to, at the end of 24 hours and after 14 days of treatment, then were inoculated and quantitative estimation of the yeast growth on Sabouraud′s dextrose agar plate was done. It was observed that after a period of 14 days, there was a reduction in the growth of yeast and also improvement in the clinical picture of the oral mucosa

Coded diffraction system in X-ray crystallography using a boolean phase coded aperture approximation

Science.gov (United States)

Pinilla, Samuel; Poveda, Juan; Arguello, Henry

2018-03-01

Phase retrieval is a problem present in many applications such as optics, astronomical imaging, computational biology and X-ray crystallography. Recent work has shown that the phase can be better recovered when the acquisition architecture includes a coded aperture, which modulates the signal before diffraction, such that the underlying signal is recovered from coded diffraction patterns. Moreover, this type of modulation effect, before the diffraction operation, can be obtained using a phase coded aperture, just after the sample under study. However, a practical implementation of a phase coded aperture in an X-ray application is not feasible, because it is computationally modeled as a matrix with complex entries which requires changing the phase of the diffracted beams. In fact, changing the phase implies finding a material that allows to deviate the direction of an X-ray beam, which can considerably increase the implementation costs. Hence, this paper describes a low cost coded X-ray diffraction system based on block-unblock coded apertures that enables phase reconstruction. The proposed system approximates the phase coded aperture with a block-unblock coded aperture by using the detour-phase method. Moreover, the SAXS/WAXS X-ray crystallography software was used to simulate the diffraction patterns of a real crystal structure called Rhombic Dodecahedron. Additionally, several simulations were carried out to analyze the performance of block-unblock approximations in recovering the phase, using the simulated diffraction patterns. Furthermore, the quality of the reconstructions was measured in terms of the Peak Signal to Noise Ratio (PSNR). Results show that the performance of the block-unblock phase coded apertures approximation decreases at most 12.5% compared with the phase coded apertures. Moreover, the quality of the reconstructions using the boolean approximations is up to 2.5 dB of PSNR less with respect to the phase coded aperture reconstructions.

Trocas gasosas e condutância estomática em três espécies de gramíneas Gas exchanges and stomatal conductance on three gramineous species

Directory of Open Access Journals (Sweden)

Eduardo Caruso Machado

1994-01-01

Full Text Available Avaliou-se, sob condições naturais e sem deficiência hídrica, o comportamento diário das taxas de assimilação de CO2 (A e de transpiração (E, a condutância estomática (g e a eficiência fotossintética do uso de água (E/A em milho (C4, arroz (C3 e trigo (C3. Nas três espécies, a curva de resposta de A em função da irradiância (I, apresentou a forma de uma hipérbole retangular, porém em milho não houve saturação lumínica. A resposta de g em relação a I apresentou a mesma forma, respondendo E linearmente, nas três espécies. Em relação à variação de g, a curva de resposta de A também mostrou a forma de hipérbole retangular, enquanto E respondeu linearmente. Devido à resposta diferencial de A e de E, tanto em função de I como de g, a razão E/A aumentou com o aumento de I. As espécies C3 (arroz e trigo revelaram valores maiores de E/A que a C4 (milho, em todos os níveis de I e valores de g, indicando melhor adaptabilidade da C4 na limitação de abertura estomática.Under natural condition and without water deficit, assimilation of CO2 (A and transpiration (E rates, stomatal conductance (g and photosyntetic efficiency of water use (E/A, were monitored daily on maize (C4, rice (C3 and wheat (C3. In all species, the shape of response curves of A in function of irradiance (I, was a retangular hyperbole. However, luminic saturation was not observed in maize. Stomatal conductance response curve in function of I was also a retangular hyperbole, while E was linear in all species. Due to differential response of A and E, as a function of I as well as g, the ratio E/A was increased with the increase of I. The C3 species (rice and wheat showed higher values of E/A than the C4 specie (maize, in all levels of I and g, showing the better C4 adaptation when stomatal limitation aperture occurs.

Recurrent aphthous stomatitis (RAS and exfoliative cheilitis in elderly psoriasis sufferer

Directory of Open Access Journals (Sweden)

Siti Hardiyanti Nurhasanah

2016-04-01

Full Text Available Recurrent Aphthous Stomatitis (RAS is a disorder in the oral cavity, with a characterized symptom as ulceration, recurrent and very painfull. The etiology is idiopathic, with multifactorial predisposition. Exfoliative cheilitis is a persistent lesion on the lip, with a characterized cracking and desquamative, with crustae and inflammation. An elderly male (72 yrs suffered with ulcer on his oral cavity, cracking lips and pain on both of his cheeks, skin, since 5 years ago. The pain is recurrent. On the clinical examination, there were some desquamation, both on the skin and vermilion border, whether on the inner lips (labial fold mucosa, there were ulcers with diameter about 1 cm. The laboratory test was within normal limits, except the LED was 40 mm/hour (n:<15. The diagnosis was Recurrent Aphthous Stomatitis (RAS for the ulcer and Exfoliative cheilitis for the cracking lips. The treatment he received was a gargle liquid, topical corticosteroid and supplement. The skin’s disorder was revered to the skin and genital disease department, for further management. As a dental general practioner, had to be very careful and familiar for every changes that may be occur both in the outer or inner oral cavity. Other disorder that need refferal, had to be done with team work, to the colleague from the right connection.

Nonparaxial propagation and focusing properties of azimuthal-variant vector fields diffracted by an annular aperture.

Science.gov (United States)

Gu, Bing; Xu, Danfeng; Pan, Yang; Cui, Yiping

2014-07-01

Based on the vectorial Rayleigh-Sommerfeld integrals, the analytical expressions for azimuthal-variant vector fields diffracted by an annular aperture are presented. This helps us to investigate the propagation behaviors and the focusing properties of apertured azimuthal-variant vector fields under nonparaxial and paraxial approximations. The diffraction by a circular aperture, a circular disk, or propagation in free space can be treated as special cases of this general result. Simulation results show that the transverse intensity, longitudinal intensity, and far-field divergence angle of nonparaxially apertured azimuthal-variant vector fields depend strongly on the azimuthal index, the outer truncation parameter and the inner truncation parameter of the annular aperture, as well as the ratio of the waist width to the wavelength. Moreover, the multiple-ring-structured intensity pattern of the focused azimuthal-variant vector field, which originates from the diffraction effect caused by an annular aperture, is experimentally demonstrated.

Infrared remote sensing for canopy temperature in paddy field and relationship between leaf temperature and leaf color

International Nuclear Information System (INIS)

Wakiyama, Y.

2002-01-01

Infrared remote sensing is used for crop monitoring, for example evaluation of water stress, detection of infected crops and estimation of transpiration and photosynthetic rates. This study was conducted to show another application of remote sensing information. The relationship between rice leaf temperature and chlorophyll content in the leaf blade was investigated by using thermography during the ripening period. The canopy of a rice community fertilized by top dressing was cooler than that not fertilized in a 1999 field experiment. In an experiment using thermocouples to measure leaf temperature, a rice leaf with high chlorophyll content was also cooler than that with a low chlorophyll content. Transpiration resistance and transpiration rate were measured with a porometer. Transpiration rate was higher with increasing chlorophyll content in the leaf blade. Stomatal aperture is related to chlorophyll content in the leaf blade. High degree of stomatal aperture is caused by high chlorophyll content in the leaf blade. As degree of stomatal aperture increases, transpiration rate increases. Therefore the rice leaf got cooler with increasing chlorophyll content in leaf blade. Paddy rice communities with different chlorophyll contents were provided with fertilization of different nitrogen levels on basal and top dressing in a 2000 field experiment. Canopy temperature of the rice community with high chlorophyll content was 0.85°C cooler than that of the rice community with low chlorophyll content. Results of this study revealed that infrared remote sensing could detect difference in chlorophyll contents in rice communities and could be used in fertilizer management in paddy fields. (author)

Stomatal Closure and SA-, JA/ET-Signaling Pathways Are Essential for Bacillus amyloliquefaciens FZB42 to Restrict Leaf Disease Caused by Phytophthora nicotianae in Nicotiana benthamiana

Directory of Open Access Journals (Sweden)

Liming Wu

2018-04-01

Full Text Available Bacillus amyloliquefaciens FZB42 is a plant growth-promoting rhizobacterium that induces resistance to a broad spectrum of pathogens. This study analyzed the mechanism by which FZB42 restricts leaf disease caused by Phytophthora nicotianae in Nicotiana benthamiana. The oomycete foliar pathogen P. nicotianae is able to reopen stomata which had been closed by the plant innate immune response to initiate penetration and infection. Here, we showed that root colonization by B. amyloliquefaciens FZB42 restricted pathogen-mediated stomatal reopening in N. benthamiana. Abscisic acid (ABA and salicylic acid (SA-regulated pathways mediated FZB42-induced stomatal closure after pathogen infection. Moreover, the defense-related genes PR-1a, LOX, and ERF1, involved in the SA and jasmonic acid (JA/ethylene (ET signaling pathways, respectively, were overexpressed, and levels of the hormones SA, JA, and ET increased in the leaves of B. amyloliquefaciens FZB42-treated wild type plants. Disruption of one of these three pathways in N. benthamiana plants increased susceptibility to the pathogen. These suggest that SA- and JA/ET-dependent signaling pathways were important in plant defenses against the pathogen. Our data thus explain a biocontrol mechanism of soil rhizobacteria in a plant.

An Anomaly Detector Based on Multi-aperture Mapping for Hyperspectral Data

Directory of Open Access Journals (Sweden)

LI Min

2016-10-01

Full Text Available Considering the correlationship of spectral content between anomaly and clutter background, inaccurate selection of background pixels induced estimation error of background model. In order to solve the above problems, a multi-aperture mapping based anomaly detector was proposed in this paper. Firstly, differing from background model which focused on feature extraction of background, multi-aperture mapping of hyperspectral data characterized the feature of whole hyperspectral data. According to constructed basis set of multi-aperture mapping, anomaly salience index of every test pixel was proposed to measure the relative statistic difference. Secondly, in order to analysis the moderate salience anomaly precisely, membership value was constructed to identify anomaly salience of test pixels continuously based on fuzzy logical theory. At same time, weighted iterative estimation of multi-aperture mapping was expected to converge adaptively with membership value as weight. Thirdly, classical defuzzification was proposed to fuse different detection results. Hyperspectral data was used in the experiments, and the robustness and sensitivity to anomaly with lower silence of proposed detector were tested.

Vesicular Stomatitis Virus Infection Promotes Immune Evasion by Preventing NKG2D-Ligand Surface Expression

DEFF Research Database (Denmark)

Jensen, Helle; Andresen, Lars; Nielsen, Jens

2011-01-01

Vesicular stomatitis virus (VSV) has recently gained attention for its oncolytic ability in cancer treatment. Initially, we hypothesized that VSV infection could increase immune recognition of cancer cells through induction of the immune stimulatory NKG2D-ligands. Here we show that VSV infection ...

Aperture Valve for the Mars Organic Molecule Analyzer (MOMA)

Science.gov (United States)

Hakun, Claef F.; Engler, Charles D.; Barber, Willie E.; Canham, John S.

2014-01-01

NASA's participation in the multi-nation ExoMars 2018 Rover mission includes a critical astrobiology Mass Spectrometer Instrument on the Rover called the Mars Organic Molecule Analyzer (MOMA). The Aperture Valve is a critical electromechanical valve used by the Mass Spectrometer to facilitate the transfer of ions from Martian soil to the Mass Spectrometer for analysis. The MOMA Aperture Valve development program will be discussed in terms of the Initial valve design and subsequent improvements that resulted from prototype testing. The Initial Aperture Valve concept seemed promising, based on calculations and perceived merits. However, performance results of this design were disappointing, due to delamination of TiN and DLC coatings applied to the Titanium base metals, causing debris from the coatings to seize the valve. While peer reviews and design trade studies are important forums to vet a concept design, results from testing should not be underestimated.Despite the lack of development progress to meet requirements, valuable information from weakness discovered in the Initial Valve design was used to develop a second, more robust Aperture valve. Based on a check-ball design, the ETU flight valve design resulted in significantly less surface area to create the seal. Moreover, PVD coatings were eliminated in favor of hardened, nonmagnetic corrosion resistant alloys. Test results were impressive, with the valve achieving five orders of magnitude better sealing leak rate over end of life requirements. Cycle life was equally impressive, achieving 280,000 cycles without failure.

Study on characteristics of the aperture-averaging factor of atmospheric scintillation in terrestrial optical wireless communication

Science.gov (United States)

Shen, Hong; Liu, Wen-xing; Zhou, Xue-yun; Zhou, Li-ling; Yu, Long-Kun

2018-02-01

In order to thoroughly understand the characteristics of the aperture-averaging effect of atmospheric scintillation in terrestrial optical wireless communication and provide references for engineering design and performance evaluation of the optics system employed in the atmosphere, we have theoretically deduced the generally analytic expression of the aperture-averaging factor of atmospheric scintillation, and numerically investigated characteristics of the apertureaveraging factor under different propagation conditions. The limitations of the current commonly used approximate calculation formula of aperture-averaging factor have been discussed, and the results showed that the current calculation formula is not applicable for the small receiving aperture under non-uniform turbulence link. Numerical calculation has showed that aperture-averaging factor of atmospheric scintillation presented an exponential decline model for the small receiving aperture under non-uniform turbulent link, and the general expression of the model was given. This model has certain guiding significance for evaluating the aperture-averaging effect in the terrestrial optical wireless communication.

Preliminary study of insertion device effect on dynamic aperture using RACETRACK

International Nuclear Information System (INIS)

Chae, Yong-chul; Crosbie, E.A.

1992-01-01

We studied the effects of an insertion device (ID) on the dynamic aperture using the new version of RACETRACK. We found that the nonlinear effect of the ID is the dominant effect on the dynamic aperture reduction compared to the other multipole errors which exist in the otherwise ideal lattice. The previous study of dynamic aperture was based on the assumption that the effect of the fast oscillating terms in L. Smith's Hamiltonian is small, and hence can be neglected in the simulation. The remarkable agreement between the previous study and the current results using RACETRACK, including all effects of the fast oscillating terms, justified those assumptions at least for the APS ring

Lack of photosynthetic or stomatal regulation after 9 years of elevated [CO2] and 4 years of soil warming in two conifer species at the alpine treeline.

Science.gov (United States)

Streit, Kathrin; Siegwolf, Rolf T W; Hagedorn, Frank; Schaub, Marcus; Buchmann, Nina

2014-02-01

Alpine treelines are temperature-limited vegetation boundaries. Understanding the effects of elevated [CO2 ] and warming on CO2 and H2 O gas exchange may help predict responses of treelines to global change. We measured needle gas exchange of Larix decidua Mill. and Pinus mugo ssp. uncinata DC trees after 9 years of free air CO2 enrichment (575 µmol mol(-1) ) and 4 years of soil warming (+4 °C) and analysed δ(13) C and δ(18) O values of needles and tree rings. Tree needles under elevated [CO2 ] showed neither nitrogen limitation nor end-product inhibition, and no down-regulation of maximal photosynthetic rate (Amax ) was found. Both tree species showed increased net photosynthetic rates (An ) under elevated [CO2 ] (L. decidua: +39%; P. mugo: +35%). Stomatal conductance (gH2O ) was insensitive to changes in [CO2 ], thus transpiration rates remained unchanged and intrinsic water-use efficiency (iWUE) increased due to higher An . Soil warming affected neither An nor gH2O . Unresponsiveness of gH2O to [CO2 ] and warming was confirmed by δ(18) O needle and tree ring values. Consequently, under sufficient water supply, elevated [CO2 ] induced sustained enhancement in An and lead to increased C inputs into this ecosystem, while soil warming hardly affected gas exchange of L. decidua and P. mugo at the alpine treeline. © 2013 John Wiley & Sons Ltd.

Synthetic tracked aperture ultrasound imaging: design, simulation, and experimental evaluation.

Science.gov (United States)

Zhang, Haichong K; Cheng, Alexis; Bottenus, Nick; Guo, Xiaoyu; Trahey, Gregg E; Boctor, Emad M

2016-04-01

Ultrasonography is a widely used imaging modality to visualize anatomical structures due to its low cost and ease of use; however, it is challenging to acquire acceptable image quality in deep tissue. Synthetic aperture (SA) is a technique used to increase image resolution by synthesizing information from multiple subapertures, but the resolution improvement is limited by the physical size of the array transducer. With a large F-number, it is difficult to achieve high resolution in deep regions without extending the effective aperture size. We propose a method to extend the available aperture size for SA-called synthetic tracked aperture ultrasound (STRATUS) imaging-by sweeping an ultrasound transducer while tracking its orientation and location. Tracking information of the ultrasound probe is used to synthesize the signals received at different positions. Considering the practical implementation, we estimated the effect of tracking and ultrasound calibration error to the quality of the final beamformed image through simulation. In addition, to experimentally validate this approach, a 6 degree-of-freedom robot arm was used as a mechanical tracker to hold an ultrasound transducer and to apply in-plane lateral translational motion. Results indicate that STRATUS imaging with robotic tracking has the potential to improve ultrasound image quality.

Deliberate ROS production and auxin synergistically trigger the asymmetrical division generating the subsidiary cells in Zea mays stomatal complexes.

Science.gov (United States)

Livanos, Pantelis; Galatis, Basil; Apostolakos, Panagiotis

2016-07-01

Subsidiary cell generation in Poaceae is an outstanding example of local intercellular stimulation. An inductive stimulus emanates from the guard cell mother cells (GMCs) towards their laterally adjacent subsidiary cell mother cells (SMCs) and triggers the asymmetrical division of the latter. Indole-3-acetic acid (IAA) immunolocalization in Zea mays protoderm confirmed that the GMCs function as local sources of auxin and revealed that auxin is polarly accumulated between GMCs and SMCs in a timely-dependent manner. Besides, staining techniques showed that reactive oxygen species (ROS) exhibit a closely similar, also time-dependent, pattern of appearance suggesting ROS implication in subsidiary cell formation. This phenomenon was further investigated by using the specific NADPH-oxidase inhibitor diphenylene iodonium, the ROS scavenger N-acetyl-cysteine, menadione which leads to ROS overproduction, and H2O2. Treatments with diphenylene iodonium, N-acetyl-cysteine, and menadione specifically blocked SMC polarization and asymmetrical division. In contrast, H2O2 promoted the establishment of SMC polarity and subsequently subsidiary cell formation in "younger" protodermal areas. Surprisingly, H2O2 favored the asymmetrical division of the intervening cells of the stomatal rows leading to the creation of extra apical subsidiary cells. Moreover, H2O2 altered IAA localization, whereas synthetic auxin analogue 1-napthaleneacetic acid enhanced ROS accumulation. Combined treatments with ROS modulators along with 1-napthaleneacetic acid or 2,3,5-triiodobenzoic acid, an auxin efflux inhibitor, confirmed the crosstalk between ROS and auxin functioning during subsidiary cell generation. Collectively, our results demonstrate that ROS are critical partners of auxin during development of Z. mays stomatal complexes. The interplay between auxin and ROS seems to be spatially and temporarily regulated.

Swamp plots for dynamic aperture studies of PEP-II lattices

International Nuclear Information System (INIS)

Yan, Y.T.; Irwin, J.; Cai, Y.; Chen, T.; Ritson, D.

1995-01-01

With a newly developed algorithm using resonance basis Lie generators and their evaluation with action-angle Poisson bracket maps (nPB tracking) the authors have been able to perform fast tracking for dynamic aperture studies of PEP-II lattices as well as incorporate lattice nonlinearities in beam-beam studies. They have been able to better understand the relationship between dynamic apertures and the tune shift and resonance coefficients in the generators of the one-turn maps. To obtain swamp plots (dynamic aperture vs. working point) of the PEP-II lattices, they first compute a one-turn resonance basis map for a nominal working point and then perform nPB tracking by switching the working point while holding fixed all other terms in the map. Results have been spot-checked by comparing with element-by-element tracking

Analytical estimation of the dynamic apertures of circular accelerators

International Nuclear Information System (INIS)

Gao, J.

2000-02-01

By considering delta function sextupole, octupole, and deca-pole perturbations and using difference action-angle variable equations, we find some useful analytical formulae for the estimation of the dynamic apertures of circular accelerators due to single sextupole, single octupole, single deca-pole (single 2 m pole in general). Their combined effects are derived based on the Chirikov criterion of the onset of stochastic motions. Comparisons with numerical simulations are made, and the agreement is quite satisfactory. These formulae have been applied to determine the beam-beam limited dynamic aperture in a circular collider. (author)

Evolution of the bHLH genes involved in stomatal development: implications for the expansion of developmental complexity of stomata in land plants.

Directory of Open Access Journals (Sweden)

Jin-Hua Ran

Full Text Available Stomata play significant roles in plant evolution. A trio of closely related basic Helix-Loop-Helix (bHLH subgroup Ia genes, SPCH, MUTE and FAMA, mediate sequential steps of stomatal development, and their functions may be conserved in land plants. However, the evolutionary history of the putative SPCH/MUTE/FAMA genes is still greatly controversial, especially the phylogenetic positions of the bHLH Ia members from basal land plants. To better understand the evolutionary pattern and functional diversity of the bHLH genes involved in stomatal development, we made a comprehensive evolutionary analysis of the homologous genes from 54 species representing the major lineages of green plants. The phylogenetic analysis indicated: (1 All bHLH Ia genes from the two basal land plants Physcomitrella and Selaginella were closely related to the FAMA genes of seed plants; and (2 the gymnosperm 'SPCH' genes were sister to a clade comprising the angiosperm SPCH and MUTE genes, while the FAMA genes of gymnosperms and angiosperms had a sister relationship. The revealed phylogenetic relationships are also supported by the distribution of gene structures and previous functional studies. Therefore, we deduce that the function of FAMA might be ancestral in the bHLH Ia subgroup. In addition, the gymnosperm "SPCH" genes may represent an ancestral state and have a dual function of SPCH and MUTE, two genes that could have originated from a duplication event in the common ancestor of angiosperms. Moreover, in angiosperms, SPCHs have experienced more duplications and harbor more copies than MUTEs and FAMAs, which, together with variation of the stomatal development in the entry division, implies that SPCH might have contributed greatly to the diversity of stomatal development. Based on the above, we proposed a model for the correlation between the evolution of stomatal development and the genes involved in this developmental process in land plants.

Transmission of vesicular stomatitis New Jersey virus to cattle by the biting midge Culicoides sonorensis (Diptera: Ceratopogonidae).

Science.gov (United States)

Perez de Leon, Adalberto A; Tabachnick, Walter J

2006-03-01

Laboratory-reared Culicoides sonorensis Wirth & Jones were infected with vesicular stomatitis virus serotype New Jersey (family Rhabdoviridae, genus Vesiculovirus, VSNJV) through intrathoracic inoculation. After 10-d incubation at 25 degrees C, these insects were allowed to blood feed on four steers. Two other steers were exposed to VSNJV through intralingual inoculation with 10(8) tissue culture infective dose50 VSNJV. All six steers became seropositive for VSNJV. The results demonstrate the ability of C. sonorensis to transmit VSNJV to livestock. Only the animals intralingually inoculated with VSNJV showed clinical signs in the form of vesicles at the site of inoculation. Uninfected C. sonorensis allowed to feed on the exposed animals did not become infected with VSNJV. Animals infected by C. sonorensis showed a slower antibody response compared with intralingually inoculated animals. This is probably because of different amounts of virus received via insect transmission and syringe inoculation. A significant difference was found in the serum acute-phase protein alpha-1-acid glycoprotein in animals that received VSNJV through C. sonorensis transmission. These animals had previously been exposed to insect attack in the field compared with intralingually inoculated animals and C. sonorensis-infected animals that had been protected from insect attack. The failure to observe clinical signs of vesicular stomatitis through transmission of VSNJV by C. sonorensis may explain widespread subclinical infections during vesicular stomatitis epidemics.

Double Wigner distribution function of a first-order optical system with a hard-edge aperture.

Science.gov (United States)

Pan, Weiqing

2008-01-01

The effect of an apertured optical system on Wigner distribution can be expressed as a superposition integral of the input Wigner distribution function and the double Wigner distribution function of the apertured optical system. By introducing a hard aperture function into a finite sum of complex Gaussian functions, the double Wigner distribution functions of a first-order optical system with a hard aperture outside and inside it are derived. As an example of application, the analytical expressions of the Wigner distribution for a Gaussian beam passing through a spatial filtering optical system with an internal hard aperture are obtained. The analytical results are also compared with the numerical integral results, and they show that the analytical results are proper and ascendant.

Imaging examinations and diagnosis of children's ectopic uretal aperture (with a review of 68 cases)

International Nuclear Information System (INIS)

Zhai Jiankun; Liu Liwei

2004-01-01

Objective: To discuss the imaging findings and examination methods of ectopic uretal aperture in children. Methods: The clinical data, imaging methods and findings of 68 cases with ectopic uretal aperture were analyzed retrospectively. Results: In 44 cases ectopic uretal aperture were associated with duplex kidneys (DK), and in 24 cases ectopic uretal aperture were associated with dysplasia of kidneys. IVU could display direct or indirect signs of DK in all cases. While it could hardly display dysplastic kidney and ectopic uretal aperture. CT scans were performed in 8 patients, in which DK, dysplastic kidney and the draining ureters could be evaluated. Conclusion: Definitive diagnosis is made in most cases with the integrating the clinical information and IVU findings. However, CT scan is recommended in a few cases

Apparatus and method for deterministic control of surface figure during full aperture pad polishing

Science.gov (United States)

Suratwala, Tayyab Ishaq; Feit, Michael Douglas; Steele, William Augustus

2017-10-10

A polishing system configured to polish a lap includes a lap configured to contact a workpiece for polishing the workpiece; and a septum configured to contact the lap. The septum has an aperture formed therein. The radius of the aperture and radius the workpiece are substantially the same. The aperture and the workpiece have centers disposed at substantially the same radial distance from a center of the lap. The aperture is disposed along a first radial direction from the center of the lap, and the workpiece is disposed along a second radial direction from the center of the lap. The first and second radial directions may be opposite directions.

Plasticity in stomatal size and density of potato leaves under different irrigation and phosphorus regimes

DEFF Research Database (Denmark)

Sun, Yanqi; Yan, Fei; Cui, Xiaoyong

2014-01-01

The morphological features of stomata including their size and density could be modulated by environmental cues; however, the underlying mechanisms remain largely elusive. Here, the effect of different irrigation and phosphorus (P) regimes on stomatal size (SS) and stomatal density (SD) of potato...... potentially enhance water-use efficiency as exemplified by the lowered leaf δ13C under fluctuating soil moisture conditions....... leaves was investigated. The plants were grown in split-root pots under two P fertilization rates (viz., 0 and 100mgkg-1 soil, denoted as P0 and P1, respectively) and subjected to full (FI), deficit (DI), and partial root-zone drying (PRD) irrigation regimes. Results showed that SS and SD were...... unresponsive to P but significantly affected by the irrigation treatment. FI plants had the largest SS, followed by DI, and PRD the smallest; and the reverse was the case for SD. Compared to FI and DI, PRD plants had significantly lower values of specific leaf area (SLA) and leaf carbon isotope discrimination...

Stomatal conductance of semi-natural Mediterranean grasslands: Implications for the development of ozone critical levels

International Nuclear Information System (INIS)

Alonso, R.; Bermejo, V.; Sanz, J.; Valls, B.; Elvira, S.; Gimeno, B.S.

2007-01-01

Intra-genus and intra-specific variation and the influence of nitrogen enrichment on net assimilation and stomatal conductance of some annual Trifolium species of Mediterranean dehesa grasslands were assessed under experimental conditions. Also gas exchange rates were compared between some Leguminosae and Poaceae species growing in the field in a dehesa ecosystem in central Spain. The results showed that the previously reported different O 3 sensitivity of some Trifolium species growing in pots does not seem to be related to different maximum g s values. In addition, no clear differences on gas exchange rates could be attributed to Leguminosae and Poaceae families growing in the field, with intra-genus variation being more important than differences found between families. Further studies are needed to increase the database for developing a flux-based approach for setting O 3 critical levels for semi-natural Mediterranean species. - The stomatal conductance model incorporated within the EMEP DO 3 SE deposition module needs to be re-parameterised for Mediterranean semi-natural vegetation

Recurrent aphthous stomatitis: a case report

Directory of Open Access Journals (Sweden)

Xiomara Serpa-Romero

2016-07-01

Full Text Available Recurrent aphthosus stomatitis is an alteration of the oral mucosa in some cases associated with depression of the immune system that affects the tissue response at the level of the epithelium, triggering repetitive clinical picture of small and medium ulcers (3-5 mm which necrotic presented erythematous background and lasting no more than 15 days. The picture becomes recurrent, symptomatic, compromising the health of the patient who consults again with the same characteristics in oral cavity. The literature associates the process with hormonal changes, trauma, prolonged intake of medications, and stress. A case of female patient 53, who attends the service of dentistry to present multiple oral thrush that hard to swallow, drooling and feverish marked presents in Santa Marta, at the Center for Implantology and Oral Rehabilitation. According to the interrogation and clinical examination it is associated with a reactive inflammatory process caused by the intake of drugs to treat infectious or viral process, which is given the presumptive diagnosis of erythema drug. Any medication intake was suspended and additional tests are ordered antinuclear antibodies

Increasing water use efficiency along the C3 to C4 evolutionary pathway: a stomatal optimization perspective.

Science.gov (United States)

Way, Danielle A; Katul, Gabriel G; Manzoni, Stefano; Vico, Giulia

2014-07-01

C4 photosynthesis evolved independently numerous times, probably in response to declining atmospheric CO2 concentrations, but also to high temperatures and aridity, which enhance water losses through transpiration. Here, the environmental factors controlling stomatal behaviour of leaf-level carbon and water exchange were examined across the evolutionary continuum from C3 to C4 photosynthesis at current (400 μmol mol(-1)) and low (280 μmol mol(-1)) atmospheric CO2 conditions. To this aim, a stomatal optimization model was further developed to describe the evolutionary continuum from C3 to C4 species within a unified framework. Data on C3, three categories of C3-C4 intermediates, and C4 Flaveria species were used to parameterize the stomatal model, including parameters for the marginal water use efficiency and the efficiency of the CO2-concentrating mechanism (or C4 pump); these two parameters are interpreted as traits reflecting the stomatal and photosynthetic adjustments during the C3 to C4 transformation. Neither the marginal water use efficiency nor the C4 pump strength changed significantly from C3 to early C3-C4 intermediate stages, but both traits significantly increased between early C3-C4 intermediates and the C4-like intermediates with an operational C4 cycle. At low CO2, net photosynthetic rates showed continuous increases from a C3 state, across the intermediates and towards C4 photosynthesis, but only C4-like intermediates and C4 species (with an operational C4 cycle) had higher water use efficiencies than C3 Flaveria. The results demonstrate that both the marginal water use efficiency and the C4 pump strength increase in C4 Flaveria to improve their photosynthesis and water use efficiency compared with C3 species. These findings emphasize that the advantage of the early intermediate stages is predominantly carbon based, not water related. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

SU-E-J-20: Adaptive Aperture Morphing for Online Correction for Prostate Cancer Radiotherapy

International Nuclear Information System (INIS)

Sandhu, R; Qin, A; Yan, D

2014-01-01

Purpose: Online adaptive aperture morphing is desirable over translational couch shifts to accommodate not only the target position variation but also anatomic changes (rotation, deformation, and relation of target to organ-atrisks). We proposed quick and reliable method for adapting segment aperture leaves for IMRT treatment of prostate. Methods: The proposed method consists of following steps: (1) delineate the contours of prostate, SV, bladder and rectum on kV-CBCT; (2) determine prostate displacement from the rigid body registration of the contoured prostate manifested on the reference CT and the CBCT; (3) adapt the MLC segment apertures obtained from the pre-treatment IMRT planning to accommodate the shifts as well as anatomic changes. The MLC aperture adaptive algorithm involves two steps; first move the whole aperture according to prostate translational/rotational shifts, and secondly fine-tune the aperture shape to maintain the spatial relationship between the planning target contour and the MLC aperture to the daily target contour. Feasibility of this method was evaluated retrospectively on a seven-field IMRT treatment of prostate cancer patient by comparing dose volume histograms of the original plan and the aperture-adjusted plan, with/without additional segments weight optimization (SWO), on two daily treatment CBCTs selected with relative large motion and rotation. Results: For first daily treatment, the prostate rotation was significant (12degree around lateral-axis). With apertureadjusted plan, the D95 to the target was improved 25% and rectum dose (D30, D40) was reduced 20% relative to original plan on daily volumes. For second treatment-fraction, (lateral shift = 6.7mm), after adjustment target D95 improved by 3% and bladder dose (D30, maximum dose) was reduced by 1%. For both cases, extra SWO did not provide significant improvement. Conclusion: The proposed method of adapting segment apertures is promising in treatment position correction

SU-E-J-20: Adaptive Aperture Morphing for Online Correction for Prostate Cancer Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Sandhu, R; Qin, A; Yan, D [William Beaumont Hospital, Royal Oak, MI (United States)

2014-06-01

Purpose: Online adaptive aperture morphing is desirable over translational couch shifts to accommodate not only the target position variation but also anatomic changes (rotation, deformation, and relation of target to organ-atrisks). We proposed quick and reliable method for adapting segment aperture leaves for IMRT treatment of prostate. Methods: The proposed method consists of following steps: (1) delineate the contours of prostate, SV, bladder and rectum on kV-CBCT; (2) determine prostate displacement from the rigid body registration of the contoured prostate manifested on the reference CT and the CBCT; (3) adapt the MLC segment apertures obtained from the pre-treatment IMRT planning to accommodate the shifts as well as anatomic changes. The MLC aperture adaptive algorithm involves two steps; first move the whole aperture according to prostate translational/rotational shifts, and secondly fine-tune the aperture shape to maintain the spatial relationship between the planning target contour and the MLC aperture to the daily target contour. Feasibility of this method was evaluated retrospectively on a seven-field IMRT treatment of prostate cancer patient by comparing dose volume histograms of the original plan and the aperture-adjusted plan, with/without additional segments weight optimization (SWO), on two daily treatment CBCTs selected with relative large motion and rotation. Results: For first daily treatment, the prostate rotation was significant (12degree around lateral-axis). With apertureadjusted plan, the D95 to the target was improved 25% and rectum dose (D30, D40) was reduced 20% relative to original plan on daily volumes. For second treatment-fraction, (lateral shift = 6.7mm), after adjustment target D95 improved by 3% and bladder dose (D30, maximum dose) was reduced by 1%. For both cases, extra SWO did not provide significant improvement. Conclusion: The proposed method of adapting segment apertures is promising in treatment position correction

Cell-specific vacuolar calcium storage mediated by CAX1 regulates apoplastic calcium concentration, gas exchange, and plant productivity in Arabidopsis.

Science.gov (United States)

Conn, Simon J; Gilliham, Matthew; Athman, Asmini; Schreiber, Andreas W; Baumann, Ute; Moller, Isabel; Cheng, Ning-Hui; Stancombe, Matthew A; Hirschi, Kendal D; Webb, Alex A R; Burton, Rachel; Kaiser, Brent N; Tyerman, Stephen D; Leigh, Roger A

2011-01-01

The physiological role and mechanism of nutrient storage within vacuoles of specific cell types is poorly understood. Transcript profiles from Arabidopsis thaliana leaf cells differing in calcium concentration ([Ca], epidermis 60 mM) were compared using a microarray screen and single-cell quantitative PCR. Three tonoplast-localized Ca(2+) transporters, CAX1 (Ca(2+)/H(+)-antiporter), ACA4, and ACA11 (Ca(2+)-ATPases), were identified as preferentially expressed in Ca-rich mesophyll. Analysis of respective loss-of-function mutants demonstrated that only a mutant that lacked expression of both CAX1 and CAX3, a gene ectopically expressed in leaves upon knockout of CAX1, had reduced mesophyll [Ca]. Reduced capacity for mesophyll Ca accumulation resulted in reduced cell wall extensibility, stomatal aperture, transpiration, CO(2) assimilation, and leaf growth rate; increased transcript abundance of other Ca(2+) transporter genes; altered expression of cell wall-modifying proteins, including members of the pectinmethylesterase, expansin, cellulose synthase, and polygalacturonase families; and higher pectin concentrations and thicker cell walls. We demonstrate that these phenotypes result from altered apoplastic free [Ca(2+)], which is threefold greater in cax1/cax3 than in wild-type plants. We establish CAX1 as a key regulator of apoplastic [Ca(2+)] through compartmentation into mesophyll vacuoles, a mechanism essential for optimal plant function and productivity.

Sparse synthetic aperture with Fresnel elements (S-SAFE) using digital incoherent holograms

Science.gov (United States)

Kashter, Yuval; Rivenson, Yair; Stern, Adrian; Rosen, Joseph

2015-01-01

Creating a large-scale synthetic aperture makes it possible to break the resolution boundaries dictated by the wave nature of light of common optical systems. However, their implementation is challenging, since the generation of a large size continuous mosaic synthetic aperture composed of many patterns is complicated in terms of both phase matching and time-multiplexing duration. In this study we present an advanced configuration for an incoherent holographic imaging system with super resolution qualities that creates a partial synthetic aperture. The new system, termed sparse synthetic aperture with Fresnel elements (S-SAFE), enables significantly decreasing the number of the recorded elements, and it is free from positional constrains on their location. Additionally, in order to obtain the best image quality we propose an optimal mosaicking structure derived on the basis of physical and numerical considerations, and introduce three reconstruction approaches which are compared and discussed. The super-resolution capabilities of the proposed scheme and its limitations are analyzed, numerically simulated and experimentally demonstrated. PMID:26367947

Estimating variation in stomatal frequency at intra-individual, intra-site, and inter-taxonomic levels in populations of the Leonardoxa africana (Fabaceae) complex over environmental gradients in Cameroon

Science.gov (United States)

Finsinger, Walter; Dos Santos, Thibaut; McKey, Doyle

2013-07-01

Variation of stomatal frequency (stomatal density and stomatal index) includes genetically-based, potentially-adaptive variation, and variation due to phenotypic plasticity, the degree of which may be fundamental to the ability to maintain high water-use efficiency and thus to deal with environmental change. We analysed stomatal frequency and morphology (pore length, pore width) in leaves from several individuals from nine populations of four sub-species of the Leonardoxa africana complex. The dataset represents a hierarchical sampling wherein factors are nested within each level (leaves in individuals, individuals in sites, etc.), allowing estimation of the contribution of different levels to overall variation, using variance-component analysis. SI showed significant variation among sites ("site" is largely confounded with "sub-species"), being highest in the sub-species localized in the highest-elevation site. However, most of the observed variance was accounted for at intra-site and intra-individual levels. This variance could reflect great phenotypic plasticity, presumably in response to highly local variation in micro-environmental conditions.

Combining rotating-coil measurements of large-aperture accelerator magnets

CERN Document Server

AUTHOR|(CDS)2089510

2016-10-05

The rotating coil is a widely used tool to measure the magnetic field and the field errors in accelerator magnets. The coil has a length that exceeds the entire magnetic field along the longitudinal dimension of the magnet and gives therefore a two-dimensional representation of the integrated field. Having a very good precision, the rotating coil lacks in versatility. The fixed dimensions make it impractical and inapplicable in situations, when the radial coil dimension is much smaller than the aperture or when the aperture is only little covered by the coil. That being the case for rectangular apertures with large aspect ratio, where a basic measurement by the rotating coil describes the field only in a small area of the magnet. A combination of several measurements at different positions is the topic of this work. Very important for a combination is the error distribution on the measured field harmonics. To preserve the good precision of the higher-order harmonics, the combination must not rely on the main ...

Realization of a video-rate distributed aperture millimeter-wave imaging system using optical upconversion

Science.gov (United States)

Schuetz, Christopher; Martin, Richard; Dillon, Thomas; Yao, Peng; Mackrides, Daniel; Harrity, Charles; Zablocki, Alicia; Shreve, Kevin; Bonnett, James; Curt, Petersen; Prather, Dennis

2013-05-01

Passive imaging using millimeter waves (mmWs) has many advantages and applications in the defense and security markets. All terrestrial bodies emit mmW radiation and these wavelengths are able to penetrate smoke, fog/clouds/marine layers, and even clothing. One primary obstacle to imaging in this spectrum is that longer wavelengths require larger apertures to achieve the resolutions desired for many applications. Accordingly, lens-based focal plane systems and scanning systems tend to require large aperture optics, which increase the achievable size and weight of such systems to beyond what can be supported by many applications. To overcome this limitation, a distributed aperture detection scheme is used in which the effective aperture size can be increased without the associated volumetric increase in imager size. This distributed aperture system is realized through conversion of the received mmW energy into sidebands on an optical carrier. This conversion serves, in essence, to scale the mmW sparse aperture array signals onto a complementary optical array. The side bands are subsequently stripped from the optical carrier and recombined to provide a real time snapshot of the mmW signal. Using this technique, we have constructed a real-time, video-rate imager operating at 75 GHz. A distributed aperture consisting of 220 upconversion channels is used to realize 2.5k pixels with passive sensitivity. Details of the construction and operation of this imager as well as field testing results will be presented herein.

Photodynamic antimicrobial therapy in the treatment of denture stomatitis

International Nuclear Information System (INIS)

Senna, Andre Machado de

2012-01-01

Denture stomatitis (DS), also called chronic atrophic candidiasis, is the most common oral fungal infection in denture wearers. It has a multifactorial etiology, but the presence of Candida spp. biofilm on the denture is considered the most important factor for the establishment of the DS. This study aimed to evaluate the treatment of DS through the use of photodynamic antimicrobial therapy (PAT), mediated by methylene blue. For this purpose, preclinical studies and clinical trials were performed. Simulators prototypes dentures were made of methyl methacrylate polymer to serve as a basis for biofilm growth of the following species of Candida: C. albicans, C. glabrata, C. dubliniensis, C. krusei, C. tropicalis, C. parapsilosis and C. guilliermondii. Methylene blue solution at a concentration of 450 μg/mL was used as a photosensitizer. The prototypes and biofilms were irradiated with a laser of wavelength of 660 nm, potency of 100 mW, for 80 seconds. For the clinical study, subjects were divided into two groups. The first group received conventional treatment based on the use of antifungal Miconazole. The second group received the treatment by PAT. The preclinical results showed that all species of the genus Candida were susceptible to PAT, with a reduction in colonies that ranged from 2.48 to 3.93 log 10 . Clinical outcomes were evaluated for the reduction of colonies of Candida spp. located in the mucosa and in the prosthesis and relative to the improvement of the clinical aspect of the affected mucosa. Both the conventional therapy and PAT were effective in treating DS. There was no significant statistical difference between PAT and conventional treatment for any of the factors evaluated. Thus, it was concluded that PAT is effective in the treatment of denture stomatitis. (author)

Vibrating mirror system suitable for q-switching large-aperture lasers

Energy Technology Data Exchange (ETDEWEB)

Beckwith, P.J.

1977-11-01

Resonant vibrating mirrors provide a convenient means of Q-switching a laser, but large-aperture versions require careful design if the drive power is not to become excessive. This report outlines the design principles involved in the optimisation of moving-iron galvanometer drivers, and describes a prototype device with an aperture of 40 mm x 80 mm which is capable of beam deflections of + or - 40 mrad at 800 Hz. Some suggestions are made concerning more refined designs.

A circular aperture array for ultrasonic tomography and quantitative NDE

Energy Technology Data Exchange (ETDEWEB)

Nielsen, S A

1998-08-01

The main topics of this thesis are ultrasonic tomography and ultrasonic determination of elastic stiffness constants. Both issues are based on a synthetic array with transducer elements distributed uniformly along a circular aperture, i.e., a circular aperture array. The issues are treated both theoretically and experimentally by broadband pulse techniques. Ultrasonic tomography, UCT, from a circular aperture is a relatively new imaging technique in Non-destructive Evaluation (NDE) to acquire cross sectional images in bulk materials. A filtered back-projection algorithm is used to reconstruct images in four different experiments and results of attenuation, velocity and reflection tomograms in Plexiglas of AlSi-alloy cylinders are presented. Two kinds of ultrasonic tomography are introduced: bistatic and monostatic imaging. Both techniques are verified experimentally by Plexiglas cylinders. Different reconstruction artifacts are discussed and theoretical resolution constraints are discussed for various configurations of the circular aperture array. The monostatic technique is used in volumetric imaging. In the experimental verification artificial and real discontinuities in a cylindrical AlSi-alloy are compared with similar discontinuities in a Plexiglas specimen. Finally, some limitations to UCT are discussed. The circular aperture array is used to determine five independent elastic stiffness constants of a unidirectional glass/PET (Poly Ethylene Teraphtalate) laminate. Energy flux propagation and attenuation of ultrasonic waves are considered and velocity surfaces are calculated for different planes of interest. Relations between elastic stiffness constants and engineering constants (i.e., Young`s moduli, shear moduli and Poisson`s ratios) are discussed for an orthotropic composite. Six micromechanical theories are reviewed, and expressions predicting the elastic engineering constants are evaluated. The micromechanical predicted elastic stiffness constants for the

Results of the Study of Helminths-Carrying as a Comorbidity in Children with Herpetic Stomatitis

Directory of Open Access Journals (Sweden)

E.S. Suerkulov

2016-09-01

Full Text Available The paper analyzes the helminths-carrying in children with herpetic stomatitis according to the data of the department of maxillofacial surgery of the National center of mother and child welfare, and determines the relationship of oral diseases with disorders of various parts of the gastrointestinal tract.

Stomatal conductance, canopy temperature, and leaf area index estimation using remote sensing and OBIA techniques

Science.gov (United States)

S. Panda; D.M. Amatya; G. Hoogenboom

2014-01-01

Remotely sensed images including LANDSAT, SPOT, NAIP orthoimagery, and LiDAR and relevant processing tools can be used to predict plant stomatal conductance (gs), leaf area index (LAI), and canopy temperature, vegetation density, albedo, and soil moisture using vegetation indices like normalized difference vegetation index (NDVI) or soil adjusted...

Finite element Fourier and Abbe transform methods for generalization of aperture function and geometry in Fraunhofer diffraction theory

International Nuclear Information System (INIS)

Kraus, H.G.

1991-01-01

This paper discusses methods for calculating Fraunhofer intensity fields resulting from diffraction through one- and two-dimensional apertures are presented. These methods are based on the geometric concept of finite elements and on Fourier and Abbe transforms. The geometry of the two-dimensional diffracting aperture(s) is based on biquadratic isoparametric elements, which are used to define aperture(s) of complex geometry. These elements are also used to build complex amplitude and phase functions across the aperture(s) which may be of continuous or discontinuous form. The transform integrals are accurately and efficiently integrated numerically using Gaussian quadrature. The power of these methods is most evident in two dimensions, where several examples are presented which include secondary obstructions, straight and curved secondary spider supports, multiple-mirror arrays, synthetic aperture arrays, segmented mirrors, apertures covered by screens, apodization, and phase plates. Typically, the finite element Abbe transform method results in significant gains in computational efficiency over the finite element Fourier transform method, but is also subject to some loss in generality

Modelling of stomatal conductance and ozone deposition flux of Norway Spruce using deposition model

Czech Academy of Sciences Publication Activity Database

Zapletal, M.; Chroust, P.; Večeřa, Zbyněk; Mikuška, Pavel; Cudlín, Pavel; Urban, Otmar; Pokorný, Radek; Czerný, Radek; Janouš, Dalibor; Taufarová, Klára

2009-01-01

Roč. 12, 2-3 (2009), s. 75-81 ISSN 1335-339X R&D Projects: GA MŽP SP/1B7/189/07 Institutional research plan: CEZ:AV0Z60870520; CEZ:AV0Z40310501 Keywords : ozone concentration * ozone deposition * stomatal conductance * deposition velocity * resistance model * tropo-spheric ozone Subject RIV: DG - Athmosphere Sciences, Meteorology

Position measurement of the direct drive motor of Large Aperture Telescope

Science.gov (United States)

Li, Ying; Wang, Daxing

2010-07-01

Along with the development of space and astronomy science, production of large aperture telescope and super large aperture telescope will definitely become the trend. It's one of methods to solve precise drive of large aperture telescope using direct drive technology unified designed of electricity and magnetism structure. A direct drive precise rotary table with diameter of 2.5 meters researched and produced by us is a typical mechanical & electrical integration design. This paper mainly introduces position measurement control system of direct drive motor. In design of this motor, position measurement control system requires having high resolution, and precisely aligning the position of rotor shaft and making measurement, meanwhile transferring position information to position reversing information corresponding to needed motor pole number. This system has chosen high precision metal band coder and absolute type coder, processing information of coders, and has sent 32-bit RISC CPU making software processing, and gained high resolution composite coder. The paper gives relevant laboratory test results at the end, indicating the position measurement can apply to large aperture telescope control system. This project is subsidized by Chinese National Natural Science Funds (10833004).

Propagation of Bessel-Gaussian beams through a double-apertured fractional Fourier transform optical system.

Science.gov (United States)

Tang, Bin; Jiang, Chun; Zhu, Haibin

2012-08-01

Based on the scalar diffraction theory and the fact that a hard-edged aperture function can be expanded into a finite sum of complex Gaussian functions, an approximate analytical solution for Bessel-Gaussian (BG) beams propagating through a double-apertured fractional Fourier transform (FrFT) system is derived in the cylindrical coordinate. By using the approximate analytical formulas, the propagation properties of BG beams passing through a double-apertured FrFT optical system have been studied in detail by some typical numerical examples. The results indicate that the double-apertured FrFT optical system provides a convenient way for controlling the properties of the BG beams by properly choosing the optical parameters.

Registered particles onboard identification in the various apertures of GAMMA-400 space gamma-telescope

Science.gov (United States)

Arkhangelskaja, Irene

2016-07-01

GAMMA-400 (Gamma Astronomical Multifunctional Modular Apparatus) will be the gamma-telescope onboard international satellite gamma-observatory designed for particle registration in the wide energy band. Its parameters are optimized for detection of gamma-quanta with the energy ˜ 100 GeV in the main aperture. The main scientific goals of GAMMA-400 are to investigate fluxes of γ-rays and the electron-positron cosmic ray component possibly generated by dark matter particles decay or annihilation and to search for and study in detail discrete γ-ray sources, to investigate the energy spectra of Galactic and extragalactic diffuse γ-rays, and to study γ-ray bursts and γ-emission from the active Sun. This article presents analysis of detected events identification procedures and energy resolution in three apertures provide particles registration both from upper and lateral directions based on GAMMA-400 modeling due special designed software. Time and segmentation methods are used to reject backsplash (backscattering particles created when high energy γ-rays interact with the calorimeter's matter and move in the opposite direction) in the main aperture while only energy deposition analysis allows to reject this effect in the additional and lateral ones. The main aperture provides the best angular (all strip layers information analysis) and energy (energy deposition in the all detectors studying) resolution in the energy range 0.1 - 3 × 10^{3} GeV. The energy resolution in this band is 1%. Triggers in the main aperture will be formed using information about particle direction provided by time of flight system and presence of charged particle or backsplash signal formed according to analysis of energy deposition in combination of all two-layers anticoincidence systems individual detectors. In the additional aperture gamma-telescope allows to register events in the energy band 10 × 10^{-3} - 3 × 10^{3} GeV. The additional aperture energy resolution provides due to

Hand aperture patterns in prehension.

Science.gov (United States)

Bongers, Raoul M; Zaal, Frank T J M; Jeannerod, Marc

2012-06-01

Although variations in the standard prehensile pattern can be found in the literature, these alternative patterns have never been studied systematically. This was the goal of the current paper. Ten participants picked up objects with a pincer grip. Objects (3, 5, or 7cm in diameter) were placed at 30, 60, 90, or 120cm from the hands' starting location. Usually the hand was opened gradually to a maximum immediately followed by hand closing, called the standard hand opening pattern. In the alternative opening patterns the hand opening was bumpy, or the hand aperture stayed at a plateau before closing started. Two participants in particular delayed the start of grasping with respect to start of reaching, with the delay time increasing with object distance. For larger object distances and smaller object sizes, the bumpy and plateau hand opening patterns were used more often. We tentatively concluded that the alternative hand opening patterns extended the hand opening phase, to arrive at the appropriate hand aperture at the appropriate time to close the hand for grasping the object. Variations in hand opening patterns deserve attention because this might lead to new insights into the coordination of reaching and grasping. Copyright © 2011 Elsevier B.V. All rights reserved.

Transpiration and stomatal conductance in a young secondary tropical montane forest: contrasts between native trees and invasive understorey shrubs.

Science.gov (United States)

Ghimire, Chandra Prasad; Bruijnzeel, L Adrian; Lubczynski, Maciek W; Zwartendijk, Bob W; Odongo, Vincent Omondi; Ravelona, Maafaka; van Meerveld, H J Ilja

2018-04-21

It has been suggested that vigorous secondary tropical forests can have very high transpiration rates, but sap flow and stomatal conductance dynamics of trees and shrubs in these forests are understudied. In an effort to address this knowledge gap, sap flow (thermal dissipation method, 12 trees) and stomatal conductance (porometry, six trees) were measured for young (5-7 years) Psiadia altissima (DC.) Drake trees, a widely occurring species dominating young regrowth following abandonment of swidden agriculture in upland eastern Madagascar. In addition, stomatal conductance (gs) was determined for three individuals of two locally common invasive shrubs (Lantana camara L. and Rubus moluccanus L.) during three periods with contrasting soil moisture conditions. Values of gs for the three investigated species were significantly higher and more sensitive to climatic conditions during the wet period compared with the dry period. Further, gs of the understorey shrubs was much more sensitive to soil moisture content than that of the trees. Tree transpiration rates (Ec) were relatively stable during the dry season and were only affected somewhat by soil water content at the end of the dry season, suggesting the trees had continued access to soil water despite drying out of the topsoil. The Ec exhibited a plateau-shaped relation with vapour pressure deficit (VPD), which was attributed to stomatal closure at high VPD. Vapour pressure deficit was the major driver of variation in Ec, during both the wet and the dry season. Overall water use of the trees was modest, possibly reflecting low site fertility after three swidden cultivation cycles. The observed contrast in gs response to soil water and climatic conditions for the trees and shrubs underscores the need to take root distributions into account when modelling transpiration from regenerating tropical forests.

Lower responsiveness of canopy evapotranspiration rate than of leaf stomatal conductance to open-air CO2 elevation in rice.

Science.gov (United States)

Shimono, Hiroyuki; Nakamura, Hirofumi; Hasegawa, Toshihiro; Okada, Masumi

2013-08-01

An elevated atmospheric CO2 concentration ([CO2 ]) can reduce stomatal conductance of leaves for most plant species, including rice (Oryza sativa L.). However, few studies have quantified seasonal changes in the effects of elevated [CO2 ] on canopy evapotranspiration, which integrates the response of stomatal conductance of individual leaves with other responses, such as leaf area expansion, changes in leaf surface temperature, and changes in developmental stages, in field conditions. We conducted a field experiment to measure seasonal changes in stomatal conductance of the uppermost leaves and in the evapotranspiration, transpiration, and evaporation rates using a lysimeter method. The study was conducted for flooded rice under open-air CO2 elevation. Stomatal conductance decreased by 27% under elevated [CO2 ], averaged throughout the growing season, and evapotranspiration decreased by an average of 5% during the same period. The decrease in daily evapotranspiration caused by elevated [CO2 ] was more significantly correlated with air temperature and leaf area index (LAI) rather than with other parameters of solar radiation, days after transplanting, vapor-pressure deficit and FAO reference evapotranspiration. This indicates that higher air temperatures, within the range from 16 to 27 °C, and a larger LAI, within the range from 0 to 4 m(2)  m(-2) , can increase the magnitude of the decrease in evapotranspiration rate caused by elevated [CO2 ]. The crop coefficient (i.e. the evapotranspiration rate divided by the FAO reference evapotranspiration rate) was 1.24 at ambient [CO2 ] and 1.17 at elevated [CO2 ]. This study provides the first direct measurement of the effects of elevated [CO2 ] on rice canopy evapotranspiration under open-air conditions using the lysimeter method, and the results will improve future predictions of water use in rice fields. © 2013 John Wiley & Sons Ltd.

Formation and function of a new pollen aperture pattern in angiosperms: The proximal sulcus of Tillandsia leiboldiana (Bromeliaceae).

Science.gov (United States)

Albert, Béatrice; Matamoro-Vidal, Alexis; Raquin, Christian; Nadot, Sophie

2010-02-01

Pollen grains are generally surrounded by an extremely resistant wall interrupted in places by apertures that play a key role in reproduction; pollen tube growth is initiated at these sites. The shift from a proximal to distal aperture location is a striking innovation in seed plant reproduction. Reversals to proximal aperture position have only very rarely been described in angiosperms. The genus Tillandsia belongs to the Bromeliaceae family, and its aperture pattern has been described as distal monosulcate, the most widespread aperture patterns recorded in monocots and basal angiosperms. Here we report developmental and functional elements to demonstrate that the sulcate aperture in Tillandsia leiboldiana is not distal as previously described but proximal. Postmeitotic tetrad observation indicates unambiguously the proximal position of the sulcus, and in vitro germination of pollen grains confirms that the aperture is functional. This is the first report of a sulcate proximal aperture with proximal germination. The observation of microsporogenesis reveals specific features in the patterns of callose thickenings in postmeiotic tetrads.

The roles of frequency and aperture in linac accelerator design

International Nuclear Information System (INIS)

Farkas, Z.D.

1989-01-01

Expressions for accelerating structure parameters, including those that determine the peak and average power inputs required to attain a given gradient, are given as functions of aperture to wavelength ratio for a 2π/3 mode disk-loaded guide. The value of the wavelength to aperture ratio varies over a large range, corresponding to group velocities that vary from nearly zero to nearly the speed of light. The parameters exhibit proper asymptotic behavior in both limits. These parameters are benchmark values to which parameters for other modes and for other structure shapes can be compared. For example, it will be shown that the increased peak surface field to accelerating field ratio due to increased aperture to wavelength ratio can be reduced by shaping the iris profile. Structure shapes are varied not only to show possible improvement of structure parameters, but also to improve ease of mechanical fabrication and temperature control. 4 refs., 7 figs., 1 tab

An integrated structural and geochemical study of fracture aperture growth in the Campito Formation of eastern California

Science.gov (United States)

Doungkaew, N.; Eichhubl, P.

2015-12-01

Processes of fracture formation control flow of fluid in the subsurface and the mechanical properties of the brittle crust. Understanding of fundamental fracture growth mechanisms is essential for understanding fracture formation and cementation in chemically reactive systems with implications for seismic and aseismic fault and fracture processes, migration of hydrocarbons, long-term CO2 storage, and geothermal energy production. A recent study on crack-seal veins in deeply buried sandstone of east Texas provided evidence for non-linear fracture growth, which is indicated by non-elliptical kinematic fracture aperture profiles. We hypothesize that similar non-linear fracture growth also occurs in other geologic settings, including under higher temperature where solution-precipitation reactions are kinetically favored. To test this hypothesis, we investigate processes of fracture growth in quartzitic sandstone of the Campito Formation, eastern California, by combining field structural observations, thin section petrography, and fluid inclusion microthermometry. Fracture aperture profile measurements of cemented opening-mode fractures show both elliptical and non-elliptical kinematic aperture profiles. In general, fractures that contain fibrous crack-seal cement have elliptical aperture profiles. Fractures filled with blocky cement have linear aperture profiles. Elliptical fracture aperture profiles are consistent with linear-elastic or plastic fracture mechanics. Linear aperture profiles may reflect aperture growth controlled by solution-precipitation creep, with the aperture distribution controlled by solution-precipitation kinetics. We hypothesize that synkinematic crack-seal cement preserves the elliptical aperture profiles of elastic fracture opening increments. Blocky cement, on the other hand, may form postkinematically relative to fracture opening, with fracture opening accommodated by continuous solution-precipitation creep.

Results from the coded aperture neutron imaging system

International Nuclear Information System (INIS)

Brubaker, Erik; Steele, John T.; Brennan, James S.; Marleau, Peter

2010-01-01

Because of their penetrating power, energetic neutrons and gamma rays (∼1 MeV) offer the best possibility of detecting highly shielded or distant special nuclear material (SNM). Of these, fast neutrons offer the greatest advantage due to their very low and well understood natural background. We are investigating a new approach to fast-neutron imaging - a coded aperture neutron imaging system (CANIS). Coded aperture neutron imaging should offer a highly efficient solution for improved detection speed, range, and sensitivity. We have demonstrated fast neutron and gamma ray imaging with several different configurations of coded masks patterns and detectors including an 'active' mask that is composed of neutron detectors. Here we describe our prototype detector and present some initial results from laboratory tests and demonstrations.

High frame rate synthetic aperture duplex imaging

DEFF Research Database (Denmark)

Stuart, Matthias Bo; Tomov, Borislav Gueorguiev; Pihl, Michael Johannes

2013-01-01

aperture flow imaging as demonstrated in this paper. Synthetic aperture, directional beamforming, and cross-correlation are used to produce B-mode and vector velocity images at high frame rates. The frame rate equals the effective pulse repetition frequency of each imaging mode. Emissions for making the B...... estimation is −1.8% and the relative standard deviation 5.4%. The approach can thus estimate both high and low velocities with equal accuracy and thereby makes it possible to present vector flow images with a high dynamic range. Measurements are made using the SARUS research scanner, a linear array......Conventional color flow images are limited in velocity range and can either show the high velocities in systole or be optimized for the lower diastolic velocities. The full dynamics of the flow is, thus, hard to visualize. The dynamic range can be significantly increased by employing synthetic...

In situ temperature relationships of biochemical and stomatal controls of photosynthesis in four lowland tropical tree species.

Science.gov (United States)

Slot, Martijn; Winter, Klaus

2017-12-01

Net photosynthetic carbon uptake of Panamanian lowland tropical forest species is typically optimal at 30-32 °C. The processes responsible for the decrease in photosynthesis at higher temperatures are not fully understood for tropical trees. We determined temperature responses of maximum rates of RuBP-carboxylation (V CMax ) and RuBP-regeneration (J Max ), stomatal conductance (G s ), and respiration in the light (R Light ) in situ for 4 lowland tropical tree species in Panama. G s had the lowest temperature optimum (T Opt ), similar to that of net photosynthesis, and photosynthesis became increasingly limited by stomatal conductance as temperature increased. J Max peaked at 34-37 °C and V CMax ~2 °C above that, except in the late-successional species Calophyllum longifolium, in which both peaked at ~33 °C. R Light significantly increased with increasing temperature, but simulations with a photosynthesis model indicated that this had only a small effect on net photosynthesis. We found no evidence for Rubisco-activase limitation of photosynthesis. T Opt of V CMax and J Max fell within the observed in situ leaf temperature range, but our study nonetheless suggests that net photosynthesis of tropical trees is more strongly influenced by the indirect effects of high temperature-for example, through elevated vapour pressure deficit and resulting decreases in stomatal conductance-than by direct temperature effects on photosynthetic biochemistry and respiration. © 2017 John Wiley & Sons Ltd.

Rice Stomatal Closure Requires Guard Cell Plasma Membrane ATP-Binding Cassette Transporter RCN1/OsABCG5.

Science.gov (United States)

Matsuda, Shuichi; Takano, Sho; Sato, Moeko; Furukawa, Kaoru; Nagasawa, Hidetaka; Yoshikawa, Shoko; Kasuga, Jun; Tokuji, Yoshihiko; Yazaki, Kazufumi; Nakazono, Mikio; Takamure, Itsuro; Kato, Kiyoaki

2016-03-07

Water stress is one of the major environmental stresses that affect agricultural production worldwide. Water loss from plants occurs primarily through stomatal pores. Here, we report that an Oryza sativa half-size ATP-binding cassette (ABC) subfamily G protein, RCN1/OsABCG5, is involved in stomatal closure mediated by phytohormone abscisic acid (ABA) accumulation in guard cells. We found that the GFP-RCN1/OsABCG5-fusion protein was localized at the plasma membrane in guard cells. The percentage of guard cell pairs containing both ABA and GFP-RCN1/OsABCG5 increased after exogenous ABA treatment, whereas they were co-localized in guard cell pairs regardless of whether exogenous ABA was applied. ABA application resulted in a smaller increase in the percentage of guard cell pairs containing ABA in rcn1 mutant (A684P) and RCN1-RNAi than in wild-type plants. Furthermore, polyethylene glycol (drought stress)-inducible ABA accumulation in guard cells did not occur in rcn1 mutants. Stomata closure mediated by exogenous ABA application was strongly reduced in rcn1 mutants. Finally, rcn1 mutant plants had more rapid water loss from detached leaves than the wild-type plants. These results indicate that in response to drought stress, RCN1/OsABCG5 is involved in accumulation of ABA in guard cells, which is indispensable for stomatal closure. Copyright © 2016 The Author. Published by Elsevier Inc. All rights reserved.

Precise Aperture-Dependent Motion Compensation with Frequency Domain Fast Back-Projection Algorithm

Directory of Open Access Journals (Sweden)

Man Zhang

2017-10-01

Full Text Available Precise azimuth-variant motion compensation (MOCO is an essential and difficult task for high-resolution synthetic aperture radar (SAR imagery. In conventional post-filtering approaches, residual azimuth-variant motion errors are generally compensated through a set of spatial post-filters, where the coarse-focused image is segmented into overlapped blocks concerning the azimuth-dependent residual errors. However, image domain post-filtering approaches, such as precise topography- and aperture-dependent motion compensation algorithm (PTA, have difficulty of robustness in declining, when strong motion errors are involved in the coarse-focused image. In this case, in order to capture the complete motion blurring function within each image block, both the block size and the overlapped part need necessary extension leading to degeneration of efficiency and robustness inevitably. Herein, a frequency domain fast back-projection algorithm (FDFBPA is introduced to deal with strong azimuth-variant motion errors. FDFBPA disposes of the azimuth-variant motion errors based on a precise azimuth spectrum expression in the azimuth wavenumber domain. First, a wavenumber domain sub-aperture processing strategy is introduced to accelerate computation. After that, the azimuth wavenumber spectrum is partitioned into a set of wavenumber blocks, and each block is formed into a sub-aperture coarse resolution image via the back-projection integral. Then, the sub-aperture images are straightforwardly fused together in azimuth wavenumber domain to obtain a full resolution image. Moreover, chirp-Z transform (CZT is also introduced to implement the sub-aperture back-projection integral, increasing the efficiency of the algorithm. By disusing the image domain post-filtering strategy, robustness of the proposed algorithm is improved. Both simulation and real-measured data experiments demonstrate the effectiveness and superiority of the proposal.

Role of vision in aperture closure control during reach-to-grasp movements.

Science.gov (United States)

Rand, Miya K; Lemay, Martin; Squire, Linda M; Shimansky, Yury P; Stelmach, George E

2007-08-01

We have previously shown that the distance from the hand to the target at which finger closure is initiated during the reach (aperture closure distance) depends on the amplitude of peak aperture, as well as hand velocity and acceleration. This dependence suggests the existence of a control law according to which a decision to initiate finger closure during the reach is made when the hand distance to target crosses a threshold that is a function of the above movement-related parameters. The present study examined whether the control law is affected by manipulating the visibility of the hand and the target. Young adults made reach-to-grasp movements to a dowel under conditions in which the target or the hand or both were either visible or not visible. Reaching for and grasping a target when the hand and/or target were not visible significantly increased transport time and widened peak aperture. Aperture closure distance was significantly lengthened and wrist peak velocity was decreased only when the target was not visible. Further analysis showed that the control law was significantly different between the visibility-related conditions. When either the hand or target was not visible, the aperture closure distance systematically increased compared to its value for the same amplitude of peak aperture, hand velocity, and acceleration under full visibility. This implies an increase in the distance-related safety margin for grasping when the hand or target is not visible. It has been also found that the same control law can be applied to all conditions, if variables describing hand and target visibility were included in the control law model, as the parameters of the task-related environmental context, in addition to the above movement-related parameters. This suggests that that the CNS utilizes those variables for controlling grasp initiation based on a general control law.

Transpiration directly regulates the emissions of water-soluble short-chained OVOCs.

Science.gov (United States)

Rissanen, K; Hölttä, T; Bäck, J

2018-04-20

Most plant-based emissions of volatile organic compounds (VOCs) are considered mainly temperature dependent. However, certain oxygenated VOCs (OVOCs) have high water solubility; thus, also stomatal conductance could regulate their emissions from shoots. Due to their water solubility and sources in stem and roots, it has also been suggested that their emissions could be affected by transport in xylem sap. Yet, further understanding on the role of transport has been lacking until present. We used shoot-scale long-term dynamic flux data from Scots pines (Pinus sylvestris) to analyse the effects of transpiration and transport in xylem sap flow on emissions of three water soluble OVOC: methanol, acetone and acetaldehyde. We found a direct effect of transpiration on the shoot emissions of the three OVOCs. The emissions were best explained by a regression model that combined linear transpiration and exponential temperature effects. In addition, a structural equation model indicated that stomatal conductance affects emissions mainly indirectly, by regulating transpiration. A part of temperature's effect is also indirect. The tight coupling of shoot emissions to transpiration clearly evidences that these OVOCs are transported in xylem sap from their sources in roots and stem to leaves and to ambient air. This article is protected by copyright. All rights reserved.

Design of a Large Single-Aperture Dipole Magnet for HL-LHC Upgrade

CERN Document Server

Qingjin, Xu; Iio, Masami; Ogitsu, Toru; Sasaki, Kenichi; Yamamoto, Akira; Todesco, Ezio

2013-01-01

An upgrade of the low-beta insertion system for the ATLAS and Compact Muon Solenoid experiments is proposed in the high luminosity Large Hadron Collider upgrade project. It includes final beam focusing quadrupoles, beam separation and recombination dipoles, and larger aperture matching section quadrupoles. KEK is in charge of the conceptual design of the large aperture separation dipole D1. The latest design parameters are a main field of ~ 5 T at 1.9 K with Nb-Ti superconducting technology, a coil aperture of 160 mm, and a cos-theta one-layer coil with Large Hadron Collider dipole cable. Because the new D1 is expected to be operated in a very high radiation environment, radiation resistance and a cooling scheme are being carefully considered. The collaring-yoke structure is adopted to provide the mechanical support for the single-layer Nb-Ti coil. We summarize the design study of this magnet, including i) the very large iron saturation effect on field quality due to the large aperture and limited size of the...

Terahertz Near-Field Imaging Using Enhanced Transmission through a Single Subwavelength Aperture

Science.gov (United States)

Ishihara, Kunihiko; Ikari, Tomofumi; Minamide, Hiroaki; Shikata, Jun-ichi; Ohashi, Keishi; Yokoyama, Hiroyuki; Ito, Hiromasa

2005-07-01

We demonstrate terahertz (THz) near-field imaging using resonantly enhanced transmission of THz-wave radiation (λ˜ 200 μm) through a bull’s eye structure (a single subwavelength aperture surrounded by concentric periodic grooves in a metal plate). The bull’s eye structure shows extremely large enhanced transmission, which has the advantage for a single subwavelength aperture. The spatial resolution for the bull’s eye structure (with an aperture diameter d=100 μm) is evaluated in the near-field region, and a resolution of 50 μm (corresponding to λ/4) is achieved. We obtain the THz near-field images of the subwavelength metal pattern with a spatial resolution below the diffraction limit.

Coded aperture imaging system for nuclear fuel motion detection

International Nuclear Information System (INIS)

Stalker, K.T.; Kelly, J.G.

1980-01-01

A Coded Aperature Imaging System (CAIS) has been developed at Sandia National Laboratories to image the motion of nuclear fuel rods undergoing tests simulating accident conditions within a liquid metal fast breeder reactor. The tests require that the motion of the test fuel be monitored while it is immersed in a liquid sodium coolant precluding the use of normal optical means of imaging. However, using the fission gamma rays emitted by the fuel itself and coded aperture techniques, images with 1.5 mm radial and 5 mm axial resolution have been attained. Using an electro-optical detection system coupled to a high speed motion picture camera a time resolution of one millisecond can be achieved. This paper will discuss the application of coded aperture imaging to the problem, including the design of the one-dimensional Fresnel zone plate apertures used and the special problems arising from the reactor environment and use of high energy gamma ray photons to form the coded image. Also to be discussed will be the reconstruction techniques employed and the effect of various noise sources on system performance. Finally, some experimental results obtained using the system will be presented

Coded aperture material motion detection system for the ACPR

International Nuclear Information System (INIS)

McArthur, D.A.; Kelly, J.G.

1975-01-01

Single LMFBR fuel pins are being irradiated in Sandia's Annular Core Pulsed Reactor (ACPR). In these experiments single fuel pins have been driven well into the melt and vaporization regions in transients with pulse widths of about 5 ms. The ACPR is being upgraded so that it can be used to irradiate bundles of seven LMFBR fuel pins. The coded aperture material motion detection system described is being developed for this upgraded ACPR, and has for its design goals 1 mm transverse resolution (i.e., in the axial and radial directions), depth resolution of a few cm, and time resolution of 0.1 ms. The target date for development of this system is fall 1977. The paper briefly reviews the properties of coded aperture imaging, describes one possible system for the ACPR upgrade, discusses experiments which have been performed to investigate the feasibility of such a system, and describes briefly the further work required to develop such a system. The type of coded aperture to be used has not yet been fixed, but a one-dimensional section of a Fresnel zone plate appears at this time to have significant advantages

Wind energy applications of synthetic aperture radar

DEFF Research Database (Denmark)

Badger, Merete

Synthetic aperture radars (SAR), mounted on satellites or aircraft, have proven useful for ocean wind mapping. Wind speeds at the height 10 m may be retrieved from measurements of radar backscatter using empirical model functions. The resulting windfields are valuable in offshore wind energy plan...

Characterising rock fracture aperture-spacing relationships using power-law relationships: some considerations

Science.gov (United States)

Brook, Martin; Hebblewhite, Bruce; Mitra, Rudrajit

2016-04-01

The size-scaling of rock fractures is a well-studied problem in geology, especially for permeability quantification. The intensity of fractures may control the economic exploitation of fractured reservoirs because fracture intensity describes the abundance of fractures potentially available for fluid flow. Moreover, in geotechnical engineering, fractures are important for parameterisation of stress models and excavation design. As fracture data is often collected from widely-spaced boreholes where core recovery is often incomplete, accurate interpretation and representation of fracture aperture-frequency relationships from sparse datasets is important. Fracture intensity is the number of fractures encountered per unit length along a sample scanline oriented perpendicular to the fractures in a set. Cumulative frequency of fractures (F) is commonly related to fracture aperture (A) in the form of a power-law (F = aA-b), with variations in the size of the a coefficient between sites interpreted to equate to fracture frequency for a given aperture (A). However, a common flaw in this approach is that even a small change in b can have a large effect on the response of the fracture frequency (F) parameter. We compare fracture data from the Late Permian Rangal Coal Measures from Australia's Bowen Basin, with fracture data from Jurassic carbonates from the Sierra Madre Oriental, northeastern Mexico. Both power-law coefficient a and exponent b control the fracture aperture-frequency relationship in conjunction with each other; that is, power-laws with relatively low a coefficients have relatively high b exponents and vice versa. Hence, any comparison of different power-laws must take both a and b into consideration. The corollary is that different sedimentary beds in the Sierra Madre carbonates do not show ˜8× the fracture frequency for a given fracture aperture, as based solely on the comparison of coefficient a. Rather, power-law "sensitivity factors" developed from both

High performance Lyot and PIAA coronagraphy for arbitrarily shaped telescope apertures

Energy Technology Data Exchange (ETDEWEB)

Guyon, Olivier; Hinz, Philip M. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Cady, Eric [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Belikov, Ruslan [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Martinache, Frantz, E-mail: guyon@naoj.org [National Astronomical Observatory of Japan, Subaru Telescope, Hilo, HI 96720 (United States)

2014-01-10

Two high-performance coronagraphic approaches compatible with segmented and obstructed telescope pupils are described. Both concepts use entrance pupil amplitude apodization and a combined phase and amplitude focal plane mask to achieve full coronagraphic extinction of an on-axis point source. While the first concept, called Apodized Pupil Complex Mask Lyot Coronagraph (APCMLC), relies on a transmission mask to perform the pupil apodization, the second concept, called Phase-Induced Amplitude Apodization complex mask coronagraph (PIAACMC), uses beam remapping for lossless apodization. Both concepts theoretically offer complete coronagraphic extinction (infinite contrast) of a point source in monochromatic light, with high throughput and sub-λ/D inner working angle, regardless of aperture shape. The PIAACMC offers nearly 100% throughput and approaches the fundamental coronagraph performance limit imposed by first principles. The steps toward designing the coronagraphs for arbitrary apertures are described for monochromatic light. Designs for the APCMLC and the higher performance PIAACMC are shown for several monolith and segmented apertures, such as the apertures of the Subaru Telescope, Giant Magellan Telescope, Thirty Meter Telescope, the European Extremely Large Telescope, and the Large Binocular Telescope. Performance in broadband light is also quantified, suggesting that the monochromatic designs are suitable for use in up to 20% wide spectral bands for ground-based telescopes.

A future large-aperture UVOIR space observatory: reference designs

Science.gov (United States)

Rioux, Norman; Thronson, Harley; Feinberg, Lee; Stahl, H. Philip; Redding, Dave; Jones, Andrew; Sturm, James; Collins, Christine; Liu, Alice

2015-09-01

Our joint NASA GSFC/JPL/MSFC/STScI study team has used community-provided science goals to derive mission needs, requirements, and candidate mission architectures for a future large-aperture, non-cryogenic UVOIR space observatory. We describe the feasibility assessment of system thermal and dynamic stability for supporting coronagraphy. The observatory is in a Sun-Earth L2 orbit providing a stable thermal environment and excellent field of regard. Reference designs include a 36-segment 9.2 m aperture telescope that stows within a five meter diameter launch vehicle fairing. Performance needs developed under the study are traceable to a variety of reference designs including options for a monolithic primary mirror.

Comparison of arabidopsis stomatal density mutants indicates variation in water stress responses and potential epistatic effects

Science.gov (United States)

Shaneka S. Lawson; Paula M. Pijut; Charles H. Michler

2014-01-01

Recent physiological analysis of Arabidopsis stomatal density (SD) mutants indicated that SD was not the major factor controlling aboveground biomass accumulation. Despite the general theory that plants with fewer stomata have limited biomass acquisition capabilities, epf1 and several other Arabidopsis mutants varied significantly in leaf fresh...

Modelling of root ABA synthesis, stomatal conductance, transpiration and potato production under water saving irrigation regimes

DEFF Research Database (Denmark)

Plauborg, Finn; Abrahamsen, Per; Gjettermann, Birgitte

2010-01-01

. Experimental data was compared to simulated results from the new enhanced Daisy model which include modelling 2D soil water flow, abscisic acid (ABA) signalling and its effect on stomatal conductance and hence on transpiration and assimilation, and finally crop yield. The results demonstrated that the enhanced...

Conditional expression of the vesicular stomatitis virus glycoprotein gene in Escherichia coli.

OpenAIRE

Rose, J K; Shafferman, A

1981-01-01

Bacterial plasmids that directed expression of the vesicular stomatitis virus glycoprotein (G-protein) gene under control of the tryptophan operon regulatory region were constructed. A plasmid directing the synthesis of a G-protein-like protein (containing the NH2-terminal segment of seven amino acids encoded by the trpE gene fused to the complete G-protein sequence lacking only its NH2-terminal methionine) could be transformed into trpR+ (repressed) but not into trpR- (derepressed) cells. Th...

Parameter scans and accuracy estimates of the dynamical aperture of the CERN LHC