Aperture Length Research Articles

Effects of light irradiance on stomatal regulation and growth of tomato

Light is not only a primary energy source for photosynthesis but also a vital regulator of numerous processes in plants. However, high light intensity always poses a dilemma for plants: to grow or to suffer. Combining physiological techniques at plant, tissue, and cellular levels, we investigated the regulation of stomatal behaviour and cytosolic Ca2+ concentration ([Ca2+]cyt) on growth of tomato plants under different light irradiance. Overall, plants exhibited a distinct short-term (days) and a long-term (weeks) response to high light by significantly increasing shoot biomass, leaf number, leaf temperature, vapour pressure deficit, stomatal index, aperture length and guard cell length. However, most physiological parameters were significantly reduced upon high light treatment, indicating a strong negative impact of high light on photosynthesis and stomatal opening. For instance, Short- and long-term exposure to high light significantly reduced stomatal aperture width by 31.7% and 46.3%, respectively. Moreover, high light treatments significantly decreased [Ca2+]cyt from 252±39 to 52±16nM in stomatal guard cells. Aperture width, guard cell width and stomatal index were the parameters that highly significantly correlated to photosynthesis and growth of tomato plants (P<0.01) followed by aperture width/length, guard cell volume and stomatal density. These causal links revealed some insights into the fine-regulation of stomata on plant performance despite some non-stomatal factors. Therefore, stomatal parameters including aperture width/length, guard cell width, stomatal density and index and [Ca2+]cyt could be employed as physiological markers for fast and effective assessment of performance of tomato plants.

Effects of experimental warming on stomatal traits in leaves of maize (Zea may L.).

We examined the warming effects on the stomatal frequency, stomatal aperture size and shape, and their spatial distribution pattern of maize (Zea may L.) leaves using a light microscope, an electron scanning microscope, and geostatistic techniques. A field manipulative experiment was conducted to elevate canopy temperature by 2.08°C, on average. We found that experimental warming had little effect on stomatal density, but significantly increased stomatal index due to the reduction in the number of epidermal cells under the warming treatment. Warming also significantly decreased stomatal aperture length and increased stomatal aperture width. As a result, warming significantly increased the average stomatal aperture area and stomatal aperture circumference. In addition, warming dramatically changed the stomatal spatial distribution pattern with a substantial increase in the average nearest neighbor distance between stomata on both adaxial and abaxial surfaces. The spatial distribution pattern of stomata was scale dependent with regular patterns at small scales and random patterns at larger scales on both leaf surfaces. Warming caused the stomatal distribution to become more regular on both leaf surfaces with smaller L(t) values (Ripley's K-function, L(t) is an expectation of zero for any value of t) in the warming plots than the control plots.

Thecamoebians from Late Permian Gondwana sediments of peninsular India

The evolutionary history of thecamoebians (testate amoebae) extends back to the Neoproterozoic Era. However, until now, these have had a restricted, discontinuous and modest record across the world. The studied sediment of Raniganj Formation (Godavari Graben), Andhra Pradesh, India has been assigned as Late Permian on the basis of co-occurring age-diagnostic Late Permian palynomorphs. About sixteen thecamoebian species and one taxon incertae sedis have been recorded here in the palynological slides on the basis of shell morphology and morphometry. Out of these, five belong to the family Arcellidae, seven to Centropyxidae, two to Trigonopyxidae, one to Difflugiidae, one to Plagiopyxidae, and one is regarded incertae sedis. The morphometric characteristics of fossil forms resemble their corresponding extant species studied from ecologically diverse fresh water wetlands in India. In general, the ratio of shell diameter and aperture diameter of Late Permian fossil and extant specimens show significant correlation in all the studied species. Except that, the ratio of shell length and breadth is the distinguishing feature between Centropyxis aerophila and C. aerophila ‘sylvatica’, rather than the ratio of shell length and longest diameter of the shell aperture in both fossil and extant forms. The study elucidates the minimal morphological evolution in thecamoebians and their survival during mass extinction periods and stressful environmental conditions over the geological timescale.

Pathogen and Circadian Controlled 1 (PCC1) regulates polar lipid content, ABA-related responses, and pathogen defence in Arabidopsis thaliana

Pathogen and Circadian Controlled 1 (PCC1) was previously characterized as a regulator of defence against pathogens and stress-activated transition to flowering. Plants expressing an RNA interference construct for the PCC1 gene (iPCC1 plants) showed a pleiotropic phenotype. They were hypersensitive to abscisic acid (ABA) as shown by reduced germination potential and seedling establishment, as well as reduced stomatal aperture and main root length in ABA-supplemented media. In addition, iPCC1 plants displayed alterations in polar lipid contents and their corresponding fatty acids. Importantly, a significant reduction in the content of phosphatidylinositol (PI) was observed in iPCC1 leaves when compared with wild-type plants. A trend in reduced levels of 18:0 and increased levels of 18:2 and particularly 18:3 was also detected in several classes of polar lipids. The enhanced ABA-mediated responses and the reduced content of PI might be responsible for iPCC1 plants displaying a complex pattern of defence against pathogens of different lifestyles. iPCC1 plants were more susceptible to the hemi-biotrophic oomycete pathogen Phytophthora brassicae and more resistant to the necrotrophic fungal pathogen Botrytis cinerea compared with wild-type plants.

DEVELOPMENT OF DEEP DRAWING WITHOUT BLANK-HOLDER FOR PRODUCING ELLIPTIC BRASS CUPS THROUGH CONICAL DIES

This paper introduces a new technique for deep drawing of elliptic cups through a conical die without blank holder or draw beads. In this technique an elliptical-cup is produced by pushing a circular blank using a flat-headed elliptic punch through a conical die with an elliptic aperture in a single stroke. A 3D parametric finite element (FE) model was built using the commercial FE-package ANSYS/APDL. Effects of die and punch geometry including, half-cone angle, die fillet radius, die aperture length and punch fillet radius on limiting drawing ratio (LDR), drawing load and thickness strain of the cup have been investigated. A die with half cone angle of 18° has shown the best drawability for the new technique. Finite element model results showed good agreement with experimental results. A die with an aspect ratio of 2 has been used with punches having aspect ratios ranging from 2 to 2.25. Tensile tests were carried out to obtain the stress-strain behavior for the used material. A total of seven punches were used for forming sheet metal of brass (CuZn33) with initial thicknesses of 1.5, 1.9, 2.4 and 3.2 mm at different clearance ratios (c/t). The effects of blank thickness and clearance ratio on limiting drawing ratio, drawing load and thickness strain were experimentally investigated. An elliptic cup with a limiting drawing ratio (LDR) of 2.26 has been successfully achieved.

Image enhancement in forward imaging radar using modified apodisation technique

Forward imaging radar using an UWB signal has been developed by many researchers. The image quality in this radar is not satisfactory because of the limitation of aperture length. Proposed is an image enhancement method using a modified apodisation technique in forward imaging radar. An experiment is carried out to validate the proposed method. The azimuth resolution and peak-to-sidelobe ratio are improved by the proposed method by up to about 11.7% and 10 dB, respectively.

Field distributions and particle optics in main bending dipoles of Oak Ridge Spallation Neutron Source accumulator ring

The SNS accumulator ring employs 32 electro-magnetic dipoles to bend proton beams. The dipoles are typical sector magnets with relatively large aperture and short length. Thus, how to correctly treat magnetic fringe fields in the devices remains as a question. We have performed 3D computer simulations to study magnetic field distributions in the dipoles. Further, we have analyzed particle optics based on the space-dependent curvature and focusing functions in the magnets. The effect of magnetic fringe fields on the particle motion, especially the focusing/defocusing and dispersion, is investigated. The lens parameters, including the second-order aberrations, are derived and compared with the design hard-edge parameters used in the ring lattice calculations.

Electron cloud density analysis using microwave cavity resonance

We report on a method to detect an electron cloud in proton accelerators through the measurement of the phase shift of microwaves undergoing controlled reflections with an accelerator vacuum vessel. Previous phase shift measurement suffered from interference signals due to uncontrolled reflections from beamline components, leading to an unlocalized region of measurement and indeterminate normalization. The method in this paper introduces controlled reflectors about the area of interest to localize the measurement and allow normalization. This paper describes analyses of the method via theoretical calculations, electromagnetic modeling, and experimental measurements with a bench-top prototype. Dielectric thickness, location and spatial profile were varied and the effect on phase shift is described. The effect of end cap aperture length on phase shift measurement is also reported. A factor of ten enhancement in phase shift is observed at certain frequencies.

Processing of Ultrahigh-Resolution Spaceborne Sliding Spotlight SAR Data on Curved Orbit

In high-resolution spaceborne synthetic aperture radars (SARs), with increasing synthetic aperture length on curved orbits, the hyperbolic range history (HRH) assumption deteriorates, and simple analytic transfer functions in the Doppler domain used in SAR processing do not exist. A subsection HRH model is proposed. Ultra- high-resolution sliding spotlight SAR data can be handled satisfactorily, and simple analytic transform functions are used all the same. The proposed range history model is also applicable to bistatic SARs.

Dual surface acoustic wave-based active mixing in a microfluidic channel

Many applications need fast and efficient mixing of the sample and reagent with high throughput in a microfluidic channel. Due to low Reynolds number, mixing based on molecular diffusion plays an important role in a microfluidic channel. However, the diffusion based mixing process is very slow and the efficiency is low. The development of a highly efficient mixing technique is essential for lab-on-a-chip and micro-total-analysis systems. In this paper, we introduce a highly efficient active mixing technique using dual acoustic streaming field induced by surface acoustic waves in a microfluidic channel. The rapid and high efficiency active mixing of a fluorescent dye solution and deionized water in a microfluidic channel was demonstrated with single acoustic excitation by one interdigitated transducer (IDT) as well as dual excitation by two IDTs. The mixing efficiencies were investigated as a function of applied voltage and flow rates. Our results indicate that with the same operation parameters, the mixing efficiency with dual-IDT design increased to 96.7% from 69.8% achievable with the traditional single-IDT design. The effect of aperture length of the IDT on mixing efficiency was also investigated.

Metrology, Mirrors and Gratings – Advances and Challenges in Synchrotron Optics

Ultra-precise reflective and diffractive optical elements like blazed diffraction gratings or ultra-precise mirrors of flat, elliptic, parabolic, or other shapes have become key components in today's synchrotron optics. These optical components feature nanometre accuracy on a macroscopic length scale. Beamlines with extreme lengths of 100m to 1km or more (as planned for the European XFEL) will require plane mirrors characterized by a residual slope error of 50nrad rms and a curvature radius of > 1000km on a length of 800mm or even more. Diffraction limited focusing mirrors for hard X-ray application show residual slope deviations of 50nrad rms on a length of 350mm. The current slope limit for focusing mirrors in VUV-application lies at around 0.5μrad rms, one order of magnitude inferior compared to hard X-ray focusing optics, and it can still not be exceeded due to technological restrictions. The requirements for diffraction gratings are even more challenging. In addition to the challenges posed by perfect substrate quality, special attention is needed to guaranty a precise positioning of the grooves along the full aperture length. A positioning accuracy of about 20nm for the carriage system of a ruling engine is mandatory to meet the Marechal tolerance for gratings. For the manufacture of blazed and laminar gratings, we are currently establishing a new technological laboratory at the Helmholtz Zentrum Berlin (HZB), including instrumentation from Carl Zeiss. Besides the present Zeiss technology, we are also developing an advanced technology line, including a new ultra-precise ruling machine, ion etching technology as well as laser holography.

Caprock Fracture Dissolution and CO2 Leakage

Caprocks are impermeable sedimentary formations that overlie prospective geologic CO2 storage reservoirs. As such, caprocks will be relied upon to trap CO2 and prevent vertical fluid migration and leakage. Natural and industrial analogues provide evidence of long-term performance of caprocks in holding buoyant fluids. However, the large volumes of CO2 that must be injected and stored to meaningfully reduce anthropogenic greenhouse gas emissions will exert unprecedented geomechanical and geochemical burdens on caprock formations due to elevated formation pressures and brine acidification. Caprocks have inherent vulnerabilities in that wellbores, faults and fractures that transect caprock formations may provide conduits for CO2 and/or brine to leak out of the intended storage formation. As a result, a critical criterion for CO2 storage reservoir siting assessments will be to predict and reliably quantify the risk of leakage through caprock formations. We use “flow paths” as a catchall term for any fluid conduit through caprocks including pore networks, fractures and faults along with any combination of the three elements. It is useful to assess leakage rates through flow paths in terms of their individual transmissivity, T [m4], which is the product of the permeability and the cross-sectional area of the flow path. Darcy’s law can be used to relate these intrinsic flow path characteristics and the hydraulic potential (pressure) gradient to determine a volumetric flow rate, Q , or a leakage rate for the individual flow path: ![Formula][1] (1) Where P is the hydraulic potential [Pa], z is the depth [m], μ is the fluid viscosity [Pa s] and A [m2] is the cross-sectional area of the flow path perpendicular to flow, and A equals the product of average fracture aperture and fracture length normal to the flow direction. Predicting leakage potential, however, is extremely complex because assessments … [1]: /embed/mml-math-1.gif

Design and Analysis of Ultra-Wideband Split Transmit Virtual Aperture Array for Through-the-Wall Imaging

The concept of virtual aperture and the point spread function for designing and characterizing ultra-wideband near-field multiple-input multiple-output active imaging array are investigated. Combining the approach of virtual aperture desynthesis with the monostatic-to-bistatic equivalence theorem, a kind of linear UWB MIMO array, the split transmit virtual aperture (STVA) array, was designed for through-the-wall imaging. Given the virtual aperture, the STVA array is the shortest in physical aperture length. The imaging performance of the designed STVA array in the near field is fully analyzed through both numerical and measured data. The designed STVA array has been successfully applied to imaging moving targets inside buildings.

Prediction of grout penetration length into the jointed rock mass using regression analyses

In this paper, new relations are proposed to predict the gout penetration length into jointed rock mass by means of multivariate linear and non-linear regressions. Numerical analysis was used to obtain the grout penetration length into the rock mass by considering all effective rock and grout properties. The results of numerical analysis were in a good agreement with analytical methods. As a case study Bakhtiary dam and power plant of Iran was used to assess the results of prediction models. Because of many effective properties on grout penetration length and restriction of simple regression models, multivariate regression analysis was used to correlate all parameters with penetration length of grout. Effective rock joint properties as joint hydraulic aperture, orientation, roughness, spacing and trace length along with grout properties including viscosity, yield stress, pressure and grouting time were used in regression analysis. Three possible relations one linear and two non-linear relations were proposed to predict penetration length. The validation of the equations was checked by the F-test (analysis of variance) analysis. The results of all three relations showed good cross-correlations with analytical method and field data. It is concluded that the proposed relations can predict grout penetration length into the rock mass, reasonably. Key words: Multivariate regression, numerical modeling, grout penetration length,F-test analysis.

The Novel Plant Protein INAPERTURATE POLLEN1 Marks Distinct Cellular Domains and Controls Formation of Apertures in the Arabidopsis Pollen Exine

Pollen grains protect the sperm cells inside them with the help of the unique cell wall, the exine, which exhibits enormous morphological variation across plant taxa, assembling into intricate and diverse species-specific patterns. How this complex extracellular structure is faithfully deposited at precise sites and acquires precise shape within a species is not understood. Here, we describe the isolation and characterization of the novel Arabidopsis thaliana gene INAPERTURATE POLLEN1 (INP1), which is specifically involved in formation of the pollen surface apertures, which arise by restriction of exine deposition at specific sites. Loss of INP1 leads to the loss of all three apertures in Arabidopsis pollen, and INP1 protein exhibits a unique tripartite localization in developing pollen, indicative of its direct involvement in specification of aperture positions. We also show that aperture length appears to be sensitive to INP1 dosage and INP1 misexpression can affect global exine patterning. Phenotypes of some inp1 mutants indicate that Arabidopsis apertures are initiated at three nonrandom positions around the pollen equator. The identification of INP1 opens up new avenues for studies of how formation of distinct cellular domains results in the production of different extracellular morphologies.

Microphone Array Processing for Distant Speech Recognition: From Close-Talking Microphones to Far-Field Sensors

Distant speech recognition (DSR) holds the promise of the most natural human computer interface because it enables man-machine interactions through speech, without the necessity of donning intrusive body- or head-mounted microphones. Recognizing distant speech robustly, however, remains a challenge. This contribution provides a tutorial overview of DSR systems based on microphone arrays. In particular, we present recent work on acoustic beam forming for DSR, along with experimental results verifying the effectiveness of the various algorithms described here; beginning from a word error rate (WER) of 14.3% with a single microphone of a linear array, our state-of-the-art DSR system achieved a WER of 5.3%, which was comparable to that of 4.2% obtained with a lapel microphone. Moreover, we present an emerging technology in the area of far-field audio and speech processing based on spherical microphone arrays. Performance comparisons of spherical and linear arrays reveal that a spherical array with a diameter of 8.4 cm can provide recognition accuracy comparable or better than that obtained with a large linear array with an aperture length of 126 cm.

Entropy-based motion error correction for high-resolution spotlight SAR imagery

Spotlight synthetic aperture radar (SAR) is an effective way to obtain finer azimuth resolution than the achievement in strip-map mode with the same physical antenna. In general, for spotlight SAR imaging, high azimuth resolution requires long synthetic aperture length. However, in practical airborne applications, because of the inevitable atmospheric turbulence during the long flight trajectory, more complicated motion error is induced that severely degrades the focusing quality of the SAR image. It makes motion compensation (MOCO) for high-resolution spotlight (HR-Spotlight) SAR imagery more difficult than that for other SAR systems. To tackle the HR-Spotlight SAR data contaminated by the complicated motion error, a novel MOCO algorithm based on entropy minimisation is proposed, which is named by minimum entropy MOCO (ME-MOCO). In this approach, by fitting a polynomial to the motion error, the entropy of a focused image is utilised as the optimisation function of the polynomial coefficients. Attributed to damped Newton method, a modified strategy is designed, which results in that the data-driven ME-MOCO algorithm estimates high order polynomial parameters accurately and efficiently. Besides, the proposed algorithm is efficient for the capability of exploiting the fast Fourier transform through the processing chain. Real data experiments and comparisons demonstrate the effectiveness and superiority of the proposal.

Radiological evaluation by magnetic resonance of the ‘new anatomy’ of transsexual patients undergoing male to female sex reassignment surgery

Magnetic resonance (MR) is the best way to assess the new anatomy of the pelvis after male to female (MtF) sex reassignment surgery. The aim of the study was to evaluate the radiological appearance of the small pelvis after MtF surgery and to compare it with the normal women's anatomy. Fifteen patients who underwent MtF surgery were subjected to pelvic MR at least 6 months after surgery. The anthropometric parameters of the small pelvis were measured and compared with those of ten healthy women (control group). Our personal technique (creation of the mons Veneris under the pubic skin) was performed in all patients. In patients who underwent MtF surgery, the mean neovaginal depth was slightly superior than in women (P=0.009). The length of the inferior pelvic aperture and of the inlet of pelvis was higher in the control group (P<0.005). The inclination between the axis of the neovagina and the inferior pelvis aperture, the thickness of the mons Veneris and the thickness of the rectovaginal septum were comparable between the two study groups. MR consents a detailed assessment of the new pelvic anatomy after MtF surgery. The anthropometric parameters measured in our patients were comparable with those of women.

The classification of snails belonging to the subfamily Triculinae (Hydrobiidae-Prosobranchia) in Vietnam

The classification of snails belonging to the subfamily Triculinae (Hydrobiidae-Prosobranchia) in Vietnam

Ionospheric Artifacts in Simultaneous L-Band InSAR and GPS Observations

Phase artifacts in interferometric synthetic aperture radar (InSAR) images frequently degrade the interpretability of the phase and correlation signatures of terrain. Often, these distortions are attributed to spatially variable ionospheric propagation delays at two different SAR acquisition times. We present here L-band InSAR data from Iceland, California, and Hawaii. The California and Hawaii interferograms show no significant ionospheric artifacts, while the Iceland interferogram shows a maximum misregistration of three pixels in the azimuth direction, which leads to severe phase decorrelation artifacts in the InSAR image. We relate the misregistration of complex pixels seen in the interferograms to the gradient of the ionospheric total electron content (TEC) observed by global positioning system (GPS) data and confirm that indeed the phase artifacts in the Iceland interferogram are due to dispersive ionospheric propagation rather than other decorrelation factors such as neutral atmospheric delays. We develop a method to measure the spatial TEC variation at synthetic aperture length scales using dual-frequency GPS carrier phase data. We solve for the GPS data ambiguities using a low-resolution ionosphere reference derived from either available ionospheric observations or the GPS carrier phase data themselves. GPS observations show directly the level of ionospheric variability, and the spatial TEC gradient as observed by GPS predicts the misregistration of complex pixels in interferograms in all three areas. This confirmation of the cause of the image artifacts suggests that they can be routinely corrected from the InSAR data alone, provided that the sensor measures the change in TEC along the radar swath.