Reduction In Aperture Research Articles

Overexpression of MhYTP2 enhances apple water-use efficiency by activating ABA and ethylene signaling

A critical component of crop breeding is the identification of genes involved in improving water-use efficiency (WUE). We characterized MhYTP2, a gene cloned from Malus hupehensis that encodes an RNA-binding protein, to examine its role in WUE. Under both well-watered and drought conditions, overexpression of this gene enhanced WUE in transgenic plants and they accumulated more biomass than untransformed wild-type plants. This increase in WUE was probably due to enhancement of photosynthetic rate and root water uptake, and a reduction in stomatal aperture that resulted from elevated level of ABA and activated ethylene signaling. MhYTP2 was predominantly expressed in apple roots. We noted with interest that the rate of photosynthesis, instantaneous WUE, and root water potential were higher when 35S:MhYTP2 plants were used as rootstocks rather than as scions in our grafting experiments. Our results indicated that MhYTP2 has a more crucial role in the roots than in the aerial parts of the plant, and it implies that this gene can be used for improving WUE by apple rootstocks and, potentially, rootstocks of other graft-suitable crops.

The effect of natural fracture on the fluid leak-off in hydraulic fracturing treatment

Abstract Fluid leak-off phenomenon plays a critical role in hydraulic fracturing operation. This phenomenon can be very impressive in successful operation of hydraulic fracturing. This operation is very complex in fractured reservoirs due to the reaction between induced fracture and natural fractures. In this study with the cohesive element method, the effect of presence of natural fracture on the magnitude of hydraulic fracturing fluid leak-off is investigated. First of all, cohesive element and extended finite element method methods are described. The fluid flow inside hydraulic fracture and the affecting parameters on leak-off of this fluid on adjacent environment are analyzed. Then, effects of natural fracture on hydraulic fracturing direction such as deviation, leak-off and the mutual influences (which includes the changes of stress regime around the natural fracture) and also changes in pore pressure are processed. The results indicate that presence of natural fracture will cause reduction in aperture of hydraulic fracture. This decrease will lead to extension of fluid lag and eventually delaying of leak-off phenomenon. However, this effect is negligible against the positive impact due to shear and normal displacement on increasing leak-off.

A numerical study on the transient aspects of porous flows and the applicability of Darcy’s friction flow relation

In recent developments of shale reservoirs, it is important to estimate the permeabilities of hydraulic fractures accompanying the Non- Darcy effects and geometric changes. Accordingly, a new permeability estimation method that considers the varying geometric features under different flow regions is demanded. To this end, the present study introduces the generalized Darcy’s friction flow relation, especially for examining the friction factor-Reynolds number (f · Re) relationship of porous flow, which is originally used in general internal friction flow analyses. Moreover, simple hydraulic fractures comprising structured microbeads are simulated via computational fluid dynamics during fracture aperture variations under different flow conditions from laminar to turbulent. Frictional flow features, e.g., the preservation characteristics of f · Re values, are examined under different geometry and flow conditions, and the transient flow characteristics are investigated using streamline analyses. Consequently, it is verified that the f · Re values vary slightly in proportion to the geometric changes caused by aperture reduction in each medium. Even though the variations in the f · Re values are much smaller than the permeability variations, it seems to be contrary to our expectation. Otherwise, the almost linear-variation aspects of f · Re values were observed in both directional flow cases. The linear-variation aspect of f · Re values is expected to be useful in the permeability-variation estimations in porous media with changing basic geometric factors, such as hydraulic fracture closing. Moreover, it is demonstrated that regardless of aperture reduction in the same type of medium, each porous flow has a very similar power-law relation between f and Re values when the flow velocity changes from the laminar to the turbulent condition. This aspect can be effectively used for obtaining permeability estimations of the varied media, particularly under different flow conditions.

Design and analysis of a worm gear turntable off-axis assembly method in a three-grating monochromator.

To solve the problem where the actual grating aperture decreases with an increasing scanning angle during the scanning of a three-grating monochromator, we propose an off-axis assembly method for the worm gear turntable that makes it possible to suppress this aperture reduction. We simulated and compared the traditional assembly method with the off-axis assembly method in the three-grating monochromator. Results show that the actual grating aperture can be improved by the off-axis assembly method. In fact, for any one of the three gratings, when the monochromator outputs the longest wavelength in the corresponding wavelength band, the actual grating aperture increases by 45.93%. Over the entire monochromator output band, the actual grating aperture increased by an average of 32.56% and can thus improve the monochromator's output energy. Improvement of the actual grating aperture can also reduce the stray light intensity in the monochromator and improve its output signal-to-noise ratio.

400 TW operation of Orion at ultra-high contrast

The Orion facility at the Atomic Weapons Establishment in the United Kingdom has the capability to operate one of its two 500 J, 500 fs short-pulse petawatt beams at the second harmonic, the principal reason being to increase the temporal contrast of the pulse on target. This is achieved post-compression, using 3 mm thick type-1 potassium dihydrogen phosphate crystals. Since the beam diameter of the compressed pulse is ${\sim}600$ mm, it is impractical to achieve this over the full aperture due to the unavailability of the large aperture crystals. Frequency doubling was originally achieved on Orion using a circular sub-aperture of 300 mm diameter. The reduction in aperture limited the output energy to 100 J. The second-harmonic capability has been upgraded by taking two square 300 mm $\times$ 300 mm sub-apertures from the beam and combining them at focus using a single paraboloidal mirror, thus creating a 200 J, 500 fs, i.e., 400 TW facility at the second harmonic.

Integration of Dynamic Microseismic Data With a True 3D Modeling of Hydraulic-Fracture Propagation in the Vaca Muerta Shale

SummaryMicroseismic mapping during the hydraulic-fracturing processes in the Vaca Muerta (VM) Shale in Argentina shows a group of microseismic events occurring at shallower depth and at later injection time, and they clearly deviate from the growing planar hydraulic fracture. This spatial and temporal behavior of these shallow microseismic events incurs some questions regarding the nature of these events and their connectivity to the hydraulic fracture. To answer these questions, in this article, we investigate these phenomena by use of a true 3D fracture-propagation-modeling tool along with statistical analysis on the properties of microseismic events.First, we propose a novel technique in Abaqus incorporating fracture intersections in true 3D hydraulic-fracture-propagation simulations by use of a pore-pressure cohesive zone model (CZM), which is validated by comparing our numerical results with the Khristianovic-Geertsma-de Klerk (KGD) solution (Khristianovic and Zheltov 1955; Geertsma and de Klerk 1969). The simulations fully couple slot flow in the fracture with poroelasticity in the matrix and continuum-based leakoff on the fracture walls, and honor the fracture-tip effects in quasibrittle shales. By use of this model, we quantify vertical-natural-fracture activation and fluid infiltration depending on reservoir depth, fracturing-fluid viscosity, mechanical properties of the natural-fracture cohesive layer, natural-fracture conductivity, and horizontal stress contrast. The modeling results demonstrate this natural-fracture activation in coincidence with the hydraulic-fracture-growth complexities at the intersection, such as height throttling, sharp aperture reduction after the intersection, and multibranching at various heights and directions.Finally, we investigate the hydraulic-fracture intersection with a natural fracture in the multilayer VM Shale. We infer the natural-fracture location and orientation from the microseismic-events map and formation microimager log in a nearby vertical well, respectively. We integrate the other field information such as mechanical, geological, and operational data to provide a realistic hydraulic-fracturing simulation in the presence of a natural fracture. Our 3D fracturing simulations equipped with the new fracture-intersection model rigorously simulate the growth of a realistic hydraulic-connection path toward the natural fracture at shallower depths, which was in agreement with our microseismic observations.

The metabolic constituent and rooting-related enzymes responses of marigold explants to hydrogen gas during adventitious root development

Recent evidence suggests that hydrogen gas is involved in multiple physiological process in plants. However, the physiological mechanism of hydrogen gas on adventitious rooting is largely unknown. In this report, marigold (Tagetes erecta L.) was used to determine the effect of hydrogen gas on physiological changes during adventitious root development. The results showed that 50% hydrogen-rich water significantly increased root number and length of marigold explants. Hydrogen-rich water treatment provoked a significant reduction of stomatal aperture which might be associated with the increase of relative water content. Hydrogen-rich water decreased electrolyte leakage during adventitious rooting. The content of water-soluble carbohydrate, starch and soluble protein were higher in normal water-treated controls than in hydrogen-rich water-treated explants. Compared with the control, the application of hydrogen-rich water increased peroxidases, polyphenol oxidase and indoleacetic acid oxidase activity. Results indicated that hydrogen gas promotes adventitious root development through the increase of relative water content, metabolic constituents, rooting-related enzymes and simultaneously keeping cell membrane integrity.

Single-particle dynamics in a nonlinear accelerator lattice: attaining a large tune spread with octupoles in IOTA

Fermilab is constructing the Integrable Optics Test Accelerator (IOTA) as the centerpiece of the Accelerator R&D Program towards high-intensity circular machines. One of the factors limiting the beam intensity in present circular accelerators is collective instabilities, which can be suppressed by a spread of betatron frequencies (tunes) through the Landau damping mechanism or by an external damper, if the instability is slow enough. The spread is usually created by octupole magnets, which introduce the tune dependence on the amplitude and, in some cases, by a chromatic spread (tune dependence on particle's momentum). The introduction of octupoles usually has both beneficial (improved Landau damping) and harmful properties, such as a resonant behavior and a reduction of the dynamic aperture. One of the research goals at the IOTA ring is to achieve a large betatron tune spread, while retaining a large dynamic aperture, using conventional octupole magnets in a special but realistic accelerator configuration. The configuration, although not integrable by design, approximates an autonomous 2D Hamiltonian system. In this paper, we present results of computer simulations of an electron beam in the IOTA by particle tracking and the Frequency Map Analysis. The results show that the ring's octupole magnets can be configured to provide a betatron tune shift of 0.08 (for particles at large amplitudes) with the dynamical aperture of over 20 beam sigma for a 150-MeV electron beam. The influence of the synchrotron motion, lattice errors, and magnet imperfections is insignificant for the parameters and levels of tolerances set by the design of the ring. The described octupole insert could be beneficial for enhancing Landau damping in high intensity machines.

Modelling of mineral precipitation in fractures with variable aperture

Fractures act as a highly permeable conduit for flow in naturally fractured reservoir. Geo-chemical reactions inside fractures may lead to partial or complete filling of pore spaces inside fractures over time. This reduction in fracture aperture directly affects its capability to transport fluid. The current study presents a 1-D mathematical model to simulate the geochemical filling of natural fractures. The fracture walls have been represented by simple mathematical functions to reflect variable aperture of natural fractures. Mass transfer through convection/diffusion and mineral precipitation due to precipitation/dissolution reaction were solved as a simplified mathematical representation of the actual processes. Precipitation reaction is coupled with mass transport by the fluid to ensure mass conservation of reacting components. For simplification, calcite precipitation in fracture has been modelled. The effect of pressure drop, diffusion constant, type of fracture aperture profile on evolution of fracture aperture was simulated in this study. Comparison is made between increasing, decreasing and constant fracture profiles to understand their effect on fracture evolution. This study aims to present a methodology to model variable fractures and study its effect on deposition inside the fracture. The model shows that the simple parallel model over predicts the precipitation that occurs in a fracture.

Elevated CO2-Induced Responses in Stomata Require ABA and ABA Signaling

SummaryAn integral part of global environment change is an increase in the atmospheric concentration of CO2 ([CO2]) [1]. Increased [CO2] reduces leaf stomatal apertures and density of stomata that plays out as reductions in evapotranspiration [2–4]. Surprisingly, given the importance of transpiration to the control of terrestrial water fluxes [5] and plant nutrient acquisition [6], we know comparatively little about the molecular components involved in the intracellular signaling pathways by which [CO2] controls stomatal development and function [7]. Here, we report that elevated [CO2]-induced closure and reductions in stomatal density require the generation of reactive oxygen species (ROS), thereby adding a new common element to these signaling pathways. We also show that the PYR/RCAR family of ABA receptors [8, 9] and ABA itself are required in both responses. Using genetic approaches, we show that ABA in guard cells or their precursors is sufficient to mediate the [CO2]-induced stomatal density response. Taken together, our results suggest that stomatal responses to increased [CO2] operate through the intermediacy of ABA. In the case of [CO2]-induced reductions in stomatal aperture, this occurs by accessing the guard cell ABA signaling pathway. In both [CO2]-mediated responses, our data are consistent with a mechanism in which ABA increases the sensitivity of the system to [CO2] but could also be explained by requirement for a CO2-induced increase in ABA biosynthesis specifically in the guard cell lineage. Furthermore, the dependency of stomatal [CO2] signaling on ABA suggests that the ABA pathway is, in evolutionary terms, likely to be ancestral.

Trehalose and trehalose-6-phosphate induce stomatal movements and interfere with ABA-induced stomatal closure in grapevine

<p style="text-align: justify;"><strong>Aims</strong>: The effects of trehalose and trehalose-6-phosphate (T6P), among other sugars, were assessed on grapevine stomatal movements.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Epidermal peels were used to assess the effects of sugars. Low concentrations of trehalose and T6P (1 µM) induced an osmotic-independent reduction of the stomatal aperture in light conditions. Furthermore, ABA-induced stomatal closure was reduced by sugar application in association with lower accumulation of reactive oxygen species in guard cells. Similar effects, although weaker, were observed in response to the disaccharides sucrose and maltose, but not in response to the monosaccharides fructose and glucose.</p><p style="text-align: justify;"><strong>Conclusion</strong>: This study clearly highlights the effects of sugars, especially trehalose and T6P, on grapevine stomatal movements.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: This is the first time that such effects are described in grapevine and the results obtained provide new insights about the role of sugars on stomatal regulation at the whole plant level.</p>

Guard cell hydrogen peroxide and nitric oxide mediate elevated CO2 -induced stomatal movement in tomato.

Climate change as a consequence of increasing atmospheric CO2 influences plant photosynthesis and transpiration. Although the involvement of stomata in plant responses to elevated CO2 has been well established, the underlying mechanism of elevated CO2 -induced stomatal movement remains largely unknown. We used diverse techniques, including laser scanning confocal microscopy, transmission electron microscopy, biochemical methodologies and gene silencing to investigate the signaling pathway for elevated CO2 -induced stomatal movement in tomato (Solanum lycopersicum). Elevated CO2 -induced stomatal closure was dependent on the production of RESPIRATORY BURST OXIDASE 1 (RBOH1)-mediated hydrogen peroxide (H2 O2 ) and NITRATE REDUCTASE (NR)-mediated nitric oxide (NO) in guard cells in an abscisic acid (ABA)-independent manner. Silencing of OPEN STOMATA 1 (OST1) compromised the elevated CO2 -induced accumulation of H2 O2 and NO, upregulation of SLOW ANION CHANNEL ASSOCIATED 1 (SLAC1) gene expression and reduction of stomatal aperture, whereas silencing of RBOH1 or NR had no effects on the expression of OST1. Our results demonstrate that as critical signaling molecules, RBOH1-dependent H2 O2 and NR-dependent NO act downstream of OST1 that regulate SLAC1 expression and elevated CO2 -induced stomatal movement. This information is crucial to deepen the understanding of CO2 signaling pathway in guard cells.

Permeability evolution of propped artificial fractures in coal on injection of CO2

Abstract Proppants are often utilized during hydraulic fracturing to aid the retention of the fracture aperture. However, for coal the permeability enhancement may be mitigated due to proppant embedment within the natural/artificial fractures of coalbed methane reservoirs. This process may become increasingly complex if CO 2 is injected in the reservoir for enhanced recovery. The reduction in effective fracture aperture occurs under the influence of overburden stress either when CO 2 -induced coal softening causes proppant penetration into the coal fracture surface or coal swelling encroaches into the propped facture. Here permeability transformations at simulated in situ conditions were evaluated through a suite of laboratory experiments conducted on split-cores of high-rank coals. A single smooth-surface saw-cut fracture was created and the permeability evolution measured for both non-sorbing (He) and sorbing (CO 2 ) gases at constant applied confining stress of 10 MPa. Permeability was also measured for the idealized case of a uniform monolayer of #70–140 mesh quartz sand proppant sand introduced within the saw-cut fracture for coal. The increase in He permeability was as high as ~10 fold over the unpropped fracture for a monolayer of proppant sandwiched within the coal. A similar increase in permeability with the addition of proppant was observed in the case of sorptive gas (CO 2 ) for coal. For He there was an exponential increase in permeability with increasing gas pressure ( p =1–6 MPa) for coal without proppant, as expected, as the effective stress on the core was reduced. However, with CO 2 the permeability decreased in the 1–4 MPa pressure range due to either coal swelling or softening or their combination but increased above 4 MPa due to reduced effective stress. Optical profilometry pre- and post-exposure was used to quantify any surface deformation due to proppant embedment. Comparison of the fracture surface before and after showed only infrequent new isolated pits, similar to the size of the proppant grains. The slight increase in surface roughness following exposure to CO 2 was presumed due to irreversible rearrangement of the coal structure due to CO 2 uptake then loss. A mechanistic model explains the evolution of permeability in a propped artificial fracture due to interaction with a sorbing gas (CO 2 ). Permeability evolves with a characteristic “U-shaped” trend with increasing gas pressure at constant confining stress – permeability reduces to a minimum at approximately double the Langmuir pressure flanked by elevated permeabilities at either low sorptive states (low p ) or at low effective stress (high p ). An excellent fit is recovered between model and experimental observations.

Cumulative ozone effect on canopy stomatal resistance and the impact on boundary layer dynamics and CO2 assimilation at the diurnal scale: A case study for grassland in the Netherlands

AbstractBiological, chemical, and dynamical processes occurring at the surface strongly interact at diurnal scales. Therefore, this study examines the seasonal ozone impact on stomatal resistance, surface energy balance, boundary layer dynamics, and CO2 assimilation at this (sub)diurnal scale under changing conditions. We combine a seasonal canopy resistance module with a surface‐boundary layer model that solves the diurnal evolution of dynamical and chemical variables in a well‐mixed, convective boundary layer. The model is constrained with observations from Cabauw (Netherlands) for the dry year 2003, representing a well‐mixed boundary layer at midlatitudes over water‐stressed grassland. To quantify the ozone impact, the Cumulative Uptake of Ozone is calculated over a growing season, which gives an estimate of the reduction in stomatal aperture and photosynthesis. From a sensitivity analysis with mixed‐layer temperature and soil moisture content we conclude that drought is the dominant factor that determines the surface energy partitioning and limits CO2 assimilation. Although drought causes stomatal closure, the results indicate that ozone damage, nevertheless, occurs. A second sensitivity analysis with CO2 and ozone shows that ozone damage causes an increase in stomatal resistance of up to 40% under high ozone levels and that CO2‐induced stomatal closure limits ozone damage. The impact on boundary layer development through the effect of CO2 and ozone on the stomatal resistance is much smaller. At the diurnal scale soil moisture influences the surface energy partitioning, which affects the entrainment of ozone‐rich air. Due to ozone damage, the CO2 assimilation flux is reduced by about 15%.

CBCT-based dosimetric verification and alternate planning techniques to reduce the normal tissue dose in SBRT of lung patients

Purpose: Confirmation of treatment delivery accuracy in stereotactic body radiotherapy (SBRT) of lung tumors suggests the possibility of treatment margin, or aperture reduction. In this investigation, the dose delivery to lung tumors using SBRT techniques was verified, and the feasibility of normal tissue sparing via aperture reduction or altered prescription isodose line was assessed. Methods: Planned and delivered doses to the gross tumor volume (GTV) and planning target volume (PTV) were compared for 10 patients using planning CT and conebeam CT image. Potential for reduction in normal tissue dose were assessed using 2 alternate treatment plans – reduced PTVs and alternate prescription techniques. Plans were assessed using conformity index, homogeneity index and the ratio of 50% / 100% isodose volumes (R 50% ). Results: The planned and delivered mean doses were consistent to within 4%. However, the mean dose delivered to the GTV exceeded the prescription dose (Rx) by 19% and is consistent with our planning technique of prescribing to the 80% isodose line. When reducing treatment margins and retaining a constant dose-volume constraint, block margins had to be increased which produced a constant effective field aperture outside of the GTV. Prescription to a lower isodose line using stereotactic-like planning techniques yielded the only method by which the volume of the prescription isodose could be affected, although this yielded increases in normal tissue dose due to the increased monitor units required. Conversely, conventional prescription techniques using wider field apertures were effective in reducing absolute values of normal tissue dose. Although dose conformity was similar across different prescription isodose lines, homogeneity index and R 50% values were significantly different in the 60%-70% prescription isodose line plans than the 80%, 90% prescription plans. Conclusion: Traditional margin reduction techniques did not affect a reduction in the volume of normal tissue irradiated to the prescribed dose. Prescribing to low isodose lines yields reduced volumes of the prescribed dose, but at the expense of normal tissue dose.

Precise Focusing of Airborne SAR Data With Wide Apertures Large Trajectory Deviations: A Chirp Modulated Back-Projection Approach

In the area of airborne synthetic aperture radar (SAR), motion compensation (MOCO) is a crucial technique employed to correct the SAR data affected by nonlinear platform trajectory during data acquisition. Due to range-azimuth coupling and computational burden consideration, some approximations, which are valid for SAR systems of moderate aperture length, are usually adopted in commonly used MOCO approaches. However, a much more accurate SAR data processing approach is appealing to process the low-frequency SAR systems with large aperture length, such as P-band. In this paper, a new MOCO approach with high precision and high efficiency is proposed. After the ω - κ processing and the range-dependent MOCO, the analytical expression of a 2-D spectrum of a partially focused SAR image is given. Afterward, aperture reduction is achieved by a chirp modulation technique. Finally, with high precision and less computation cost, back projection along the new built short apertures (affected by the residual motion errors) is employed to yield a fairly well-focused SAR image. Experimental results on simulated and actual P-band SAR data are presented to verify the performance of the proposed approach.

MICROSTOMIA IATROGÉNICA – CORRECÇÃO POR COMISSUROTOMIA E RETALHOS MUCOSOS ROMBOIDAIS

Microstomia é o termo utilizado para descrever a redução da fenda oral. É uma complicação relativamente comum após excisão cirúrgica alargada de tumores dos lábios, causando prejuízos cosméticos e funcionais significativos. A correcção da microstomia é um desafio, estando descritas diversas técnicas cirúrgicas para o efeito. Doente do sexo masculino de 83 anos é observado com lesão verrucosa da metade esquerda do lábio inferior, cujo estudo anatomo-patológico revelou tratar-se de carcinoma espinho-celular. Foi submetido a excisão radical da lesão. Desenvolveu microstomia iatrogénica, com assimetria da fenda oral, complicação que condicionou prejuízo estético e funcional. A correcção da microstomia foi realizada através de comissurotomia esquerda, alongamento e reposicionamento do músculo orbicular dos lábios e reconstrução do vermillion por 2 retalhos mucosos romboidais, com bom resultado estético e funcional.

Inbred Background Effects On Craniofacial Shape Dysmorphology In Mice With Spry Deletions

A mutation's effect on craniofacial phenotype is modulated by genetic background, but associated developmental interactions are not well understood. Our objective was to quantify the influence of three inbred backgrounds (FVB, 129, BL6) on the expression of craniofacial dysmorphology associated with Sprouty (Spry) 1, 2, and 4 deletions in mice. We quantified adult morphology with landmarks placed on micro‐computed tomography derived surfaces of heterozygote and homozygote knockouts, and unaffected littermates of each background. Within a background strain, mice with two deletions differ strongly from controls, including a visually identifiable rounded cranium and shortened face in Spry 2 homozygotes. Although not as extreme, heterozygotes significantly differ in shape from controls in many cases. Deletion effects are significantly different between background strains after correcting for shape differences in background controls, including a larger reduction of the nasal aperture associated with Spry1 deletion on 129 background versus FVB. Spry 4 deletion on FVB results in a more projected upper face associated with diastema teeth, while the effect of it on C57 is minimal. There are significant background effects on expression of craniofacial dysmorphology associated with Spry deletions, patterns of which can help illuminate how modifier genes can influence the effects of major genetic perturbations.Grant Funding Source: NIH (1R01‐DE021708, DP2‐OD007191, RO1‐DE021420, F30‐DE022482); NSERC (238992‐12); CIHR fellowship through ACHRI to CJP

Response of stomatal density and bound gas exchange in leaves of maize to soil water deficit

Stomatal behavior in response to drought has been the focus of intensive research, but less attention has been paid to stomatal density. In this study, 5-week-old maize seedlings were exposed to different soil water contents. Stomatal density and size as well as leaf gas exchange were investigated after 2-, 4- and 6-week of treatment, which corresponded to the jointing, trumpeting, and filling stages of maize development. Results showed that new stomata were generated continually during leaf growth. Reduced soil water content significantly stimulated stomatal generation, resulting in a significant increase in stomatal density but a decrease in stomatal size and aperture. Independent of soil water conditions, stomatal density and length in the trumpeting and filling stages were greater than in the jointing stage. Irrespective of growth stage, severe water deficit significantly reduced stomatal conductance (G s), decreasing the leaf transpiration rate (T r) and net photosynthetic rate (P n). Stomatal density was significantly negatively correlated with both P n and T r but more strongly with T r, so the leaf instantaneous water use efficiency (WUE i ) correlated positively with stomatal density. In conclusion, drought led to a significant increase in stomatal density and a reduction in stomatal size and aperture, resulting in decreased P n and T r. Because the negative correlation of stomatal density to T r was stronger than that to P n, leaf WUE i tended to increase.

Extended depth-of-field imaging and ranging in a snapshot

Traditional approaches to imaging require that an increase in depth of field is associated with a reduction in numerical aperture, and hence with a reduction in resolution and optical throughput. In their seminal work, Dowski and Cathey reported how the asymmetric point-spread function generated by a cubic-phase aberration encodes the detected image such that digital recovery can yield images with an extended depth of field without sacrificing resolution [Appl. Opt.34, 1859 (1995)10.1364/AO.34.001859APOPAI1559-128X]. Unfortunately recovered images are generally visibly degraded by artifacts arising from subtle variations in point-spread functions with defocus. We report a technique that involves determination of the spatially variant translation of image components that accompanies defocus to enable determination of spatially variant defocus. This in turn enables recovery of artifact-free, extended depth-of-field images together with a two-dimensional defocus and range map of the imaged scene. We demonstrate the technique for high-quality macroscopic and microscopic imaging of scenes presenting an extended defocus of up to two waves, and for generation of defocus maps with an uncertainty of 0.036 waves.