Entrance Openings Research Articles

Hydraulic gradient and wave height control the success of estuary artificial entrance openings

Intermittently Open/Closed Estuaries (IOCEs) are dynamic, sensitive estuaries that periodically close as a function of competing marine and fluvial energies. Once closed, IOCEs are often artificially opened to relieve localised flooding. Artificial openings are generally effective as a short-term flood mitigation strategy, however, sometimes IOCEs can close immediately after excavation without draining the lagoon. In this situation, the opening does not achieve its management purpose and reimplementation is required – costing many thousands of dollars at a time and leading to adverse impacts on estuary biota. Using a dataset of 137 openings at 37 IOCEs globally, we show that the hydraulic gradient (or grade) at opening and offshore significant wave height determine whether an estuary will remain open and drain its lagoon. The hydraulic gradient represents the energy slope between the estuary and the ocean, and wave height determines the capacity of waves to infill the channel with sediment to counter offshore erosion. Artificial openings are only successful when IOCEs are opened with a hydraulic gradient steeper than 0.017 m/m (equivalent to a grade of 1:60) and when significant wave height is below 4.30 m. These findings highlight that the estuary water level alone is not a good predictor of opening success, despite it being widely used to decide when to implement artificial openings. Using near-continuous monitoring of geomorphic change at 28 artificial openings, we show that the hydraulic gradient (and grade) at the time of opening controls the rate of channel expansion, outflow velocity at the mouth, lagoon drainage rate, and the time to reach peak channel width and outflow velocities. The tidal stage at opening can be used to either speed up or slow down the rates of change, potentially reducing the occurrence of fish kills associated with rapid drainage. Although the decision to open an estuary is a complex balance between environmental, cultural, socio-economic, and practical factors, we present a simple and cost-effective way to predict if artificial openings will be successful. The thresholds of our study can be used to complement existing decision support tools, but as a standalone method, are best suited for emergency openings where draining the lagoon to reduce flooding is the main management priority.

Variant anatomy of the mandibular canal topography

This paper presents an analysis of 3D reconstruction models of the manifestation of variability of the mandible canal (canals) on both the left and right sides, their laying in the body of the mandible and the location, size and direction of the output canals. After all, the availability of minimally invasive techniques implemented in the research process helps to identify even minor anatomical variants or branches of the mandibular canal, which are quite common and do not allow the clinician to neglect them and require proper scientific evaluation. When planning reconstructive surgery on the mandible, the lack of high predictability to prevent functional complications, which are often irreversible (because the mandibular canal contains motor and sensory nerve fibers), forces us to reconsider the morphological fundamentality of its topography. Therefore, the aim of the work was to review computed tomography digital images, their analysis and identify possible anatomical variants of the canal (channels) of the mandible, as a basis for establishing its topographic features, on the left and right sides. After analyzing 426 digital CT scans of the mandible in males and females aged 25 to 75 years, 68 3D reconstruction models were reproduced using standardized X-ray diagnostic CT software Ez3D-I Original ver.5.1.9.0, used for visualizations of multimodal and multidimensional images, some of which are presented as the results of their own research. It is established that the entrance openings of the mandibular canals on both the left and right sides continue with one canal, however, in the projection of the second molar, the latter can be divided into two or three canals with high frequency. There is a difference in the diameters (Ø) of the canals and their opening – typical (in the projection of premolars on the right side) and atypical openings – in the projection of 3.6, 4.6 molars and central incisors, canines in the direction of the outlet and their location. There is no proper regular systematization of the number, topographic trajectory and size of the mandibular canals, their association or separation, as well as the direction of their exit, which requires additional vigilance not only during research but also in clinical dentistry or reconstructive surgery.

Optimising Vine Weevil, Otiorhynchus sulcatus F. (Coleoptera: Curculionidae), Monitoring Tool Design.

Simple SummaryVine weevil remains one of the most economically important insect pests of soft-fruit and ornamental crops globally. Growers currently lack effective monitoring systems to determine presence of vine weevil within crops, meaning that controls are often applied too late to prevent economic losses. Development of improved monitoring systems is currently hindered by a lack of knowledge of whether vine weevil adults select a monitoring tool based on its visual appearance. This study used paper cups as refuges to investigate the importance of colour, shape and position of entrances on monitoring tool efficacy. Results indicate that dark, tall refuges with entrances around their base were preferentially entered by adult vine weevil. This information provides the first steps towards developing improved designs for vine weevil monitoring tools.Vine weevil, Otiorhynchus sulcatus F. (Coleoptera: Curculionidae), is an economically important insect pest of horticultural crops. To identify an effective and reliable monitoring system for adult vine weevil, this study investigated the influence of colour, height and entrance position on the efficacy of a model monitoring tool using modified paper cups as refuges. Vine weevil preferences were determined by the number of individuals recorded within a refuge. When provided with a binary choice between black or white refuges, vine weevil adults showed a preference for black refuges. Vine weevils provided with a range of coloured refuges (blue, green, red and yellow) in addition to black and white refuges showed a preference for black and blue over the other colours and white refuges in group choice experiments. Refuge height and entrance position also influenced vine weevil behaviour with individuals exhibiting a preference for taller refuges and those with entrance openings around the refuge base. These results provide insights into refuge selection by adult vine weevils, which can be exploited to improve monitoring tool design. The importance of developing an effective monitoring tool for vine weevil adults as part of an integrated pest management programme is discussed.

Variability in infragravity wave processes during estuary artificial entrance openings

ABSTRACTIntermittently open/closed estuaries (IOCE) are wave‐dominated estuaries with entrances that temporarily close to the ocean. Wave–current interactions play a major role in estuary entrance morphodynamics and influence the degree of energy transfer from the ocean into the lagoon. This study utilizes artificial entrance openings of multiple ICOE in Victoria, Australia, to capture continuous hydrodynamic and geomorphic data throughout the opening cycle. We illustrate that water level oscillations in the infragravity (IG) band) are present in the basin during open entrance conditions. IG waves were observed to propagate up to 1.8 km upstream of the mouth while the entrance was open. Our work identifies that changes in cross‐sectional area, bed depth at the berm position, and offshore wave height control the magnitude of IG waves within the estuary basin. IG wave magnitude is also tidally modulated and increases with high tides when the nearshore water level is higher. Late during the drainage phase, waves were observed to track the margins of the channel, away from the thalweg, and reach the basin. IG wave energy was highest immediately after the basin had ceased draining and while channel dimensions at the mouth were within 10% of their maximum value. As the entrance aggrades, IG wave magnitude decreases in the absence of energetic offshore wave conditions. We relate the changes in IG wave magnitude and frequency to a six‐stage conceptual model of the opening–closure sequence. Within the basin, IG wave energy, height and frequency were also consistently highest closer to the mouth and decreased with distance upstream. Our findings indicate that water level oscillations in the IG band are a persistent feature in IOCE and may be the norm rather than the exception in these systems. As IG waves were captured serendipitously as part of a larger field campaign, future work will focus on instrumenting IOCE to gain high‐resolution data to quantify IG wave processes during entrance openings. © 2020 John Wiley & Sons, Ltd.

Scalable 3D Nanoparticle Trap for Electron Microscopy Analysis.

Arrays of nanoscale pyramidal cages embedded in a silicon nitride membrane are fabricated with an order of magnitude miniaturization in the size of the cages compared to previous work. This becomes possible by combining the previously published wafer-scale corner lithography process with displacement Talbot lithography, including an additional resist etching step that allows the creation of masking dots with a size down to 50 nm, using a conventional 365 nm UV source. The resulting pyramidal cages have different entrance and exit openings, which allows trapping of nanoparticles within a predefined size range. The cages are arranged in a well-defined array, which guarantees traceability of individual particles during post-trapping analysis. Gold nanoparticles with a size of 25, 150, and 200 nm are used to demonstrate the trapping capability of the fabricated devices. The traceability of individual particles is demonstrated by transferring the transmission electron microscopy (TEM) transparent devices between scanning electron microscopy and TEM instruments and relocating a desired collection of particles.

NMR structure and function of Helicoverpa armigera sterol carrier protein-2, an important insecticidal target from the cotton bollworm.

The cotton bollworm, Helicoverpa armigera, has developed strong resistance to many insecticides. Sterol Carrier Protein-2 (SCP-2) is an important non-specific lipid transfer protein in insects and appears to be a potential new target. In order to elucidate the structure and function of Helicoverpa armigera SCP-2 (HaSCP-2), NMR spectroscopy, docking simulations, mutagenesis and bioassays were performed. HaSCP-2 composed of five α-helices and four stranded β-sheets. The folds of α-helices and β-sheets interacted together to form a hydrophobic cavity with putative entrance and exit openings, which served as a tunnel for accommodating and transporting of lipids. Several sterols and fatty acids could interact with HaSCP-2 via important hydrophobic sites, which could be potential targets for insecticides. Mutagenesis experiments indicated Y51, F53, F89, F110, I117 and Q131 may be the key functional sites. HaSCP-2 showed high cholesterol binding activity and SCP-2 inhibitors (SCPIs) could inhibit the biological activity of HaSCP-2. SCPI-treated larvae at young stage showed a significant decrease of cholesterol uptake in vivo. Our study describes for the first time a NMR structure of SCP-2 in lepidopteran H. armigera and reveals its important function in cholesterol uptake, which facilitates the screening of effective insecticides targeting the insect cholesterol metabolism.

Two resonances effect for light transmission assisted with surface plasmon through perforated metal film

Abstract When light is incident on a nonplanar metal surface, an oscillating dipole is excited at the entrance openings. We show that the enhanced transmission assisted with surface plasmon (SP) through a perforated metal film results from two different SP resonances effects: (i) zero-order Fabry–Perot resonance effect where each air hole can be considered as a section of metallic waveguide, forming a low-quality-factor resonator, and many dipoles are arranged inside the nanoholes region; and (ii) structure-factor-induced charges self-tunnelling effect due to the well-recognized surface structure periodicity, where the positive or negative charges can respectively tunnel into the right surface through the metal walls. Furthermore, when light transmits through the double-layer perforated metal films, the different transport behaviors are also clearly shown, which convinces the existence of dual SP resonances effect.

Modelo arquitetônico de ninhos da formiga Ectatomma vizottoi Almeida (Hymenoptera, Formicidae)

The construction pattern and occupancy of Ectatomma vizottoi was described, during November 2004-August 2006 period, in Dourados, state of Mato Grosso do Sul by excavation of eight nests. The entrance openings, or exit, have an ellipsoid shape and lead to a wide tunnel, similar to a hall, which is connected to other deeper chambers in the nest. The nests reach up to 360 cm deep and contain three to ten chambers. Nests are constructed independently of plants and roots presence, and the soil of the tunnels and chambers are compacted, with specific compartments for colony deposit of detritus. The increase of the ant density led to an increase in nest depth and number of chambers, maintaining an average nest volume, which indicates a standard size for nest chambers.

Performance of an ultrahigh resolution cylindrical grating monochromator undulator beamline

An ultrahigh resolution and high-flux undulator beamline U9-CGM, with a cylindrical grating monochromator and covering an energy range from 5to100eV, has been constructed. Two separate entrance slits are included to provide different incident angles, hence to optimize the overall performance. This beamline delivers an average photon flux of 6×1010photons∕s with the entrance and exit slit openings at 10μm. An energy resolving power of 110 000 with a photon flux of 1×1010photons∕s was obtained at 16eV with the 1800line∕mm grating and at 64eV with the 1600line∕mm grating, with the entrance and exit slit openings at 3 and 5μm, respectively. A differentially pumped gas cell is used to attenuate high-order light by up to four orders of magnitude. This beamline will be a powerful tool for research in ultrahigh resolution spectroscopy of atoms, molecules, and condensed matter.

Origin of Quasiperiodicity in Conductance Fluctuations of Soft-Walled Chaotic Quantum Dots

Assuming that the quantum point contacts (QPCs) connecting the cavity to large reservoirs of source and drain have a transversal profile of harmonic potential that accommodates an extremely narrow Gaussian wave packet as the ground state, we deduce that quantum correction to the lowest mode transmission coefficient can be approximated as a summation over periodic orbits that are well coupled to both the entrance and exit openings. Energy averaging around the Fermi energy gives the damping factor so that only a few shortest periodic orbits contribute to conductance fluctuations. This confirms the experimental and self-consistent numerical results observed recently in quantum dots, that conductance fluctuations are dominated by a few discrete frequencies.

Assessment of Ultraviolet Radiation Exposure in the Wood Surface Coating Industry

Abstract Ultraviolet (UV) radiation curing of paints and lacquers has rapidly increased in the furniture industry. Exposure to UV radiation involves a potential health hazard to workers in this industry and there is little information on UV radiation spectra and exposure levels under these working conditions. We have investigated the intensity and spectral distribution of UV radiation and determined the maximum permissible exposure times (MPETs) at different fixed points surrounding the UV curing units. The spectral irradiance was measured between 250 and 400 nm using a calibrated diode array spectrograph, and the intensity of the UV radiation was measured using a radiometer equipped with UVA and UVB detectors. The spectral power distribution was weighted for biological effect using Wester's approximation equations of the spectral effectiveness curve adopted from the International Radiation Protection Association/International Non-Ionizing Radiation Committee. The intensity of the UV radiation at the substrate passage level ranged from 100 to 200 mW/cm2, giving MPETs of 0.6 to 0.03 seconds, respectively. MPETs varied between 8 and 126 seconds at entrance and exit openings and between 0.5 and 2.3 hours at 0.8 m from the UV curing units. Direct UV radiation from holes and fissures in the units was detected at four of the six plants; MPETs varied from 6 seconds to 3 minutes. High intensity UV radiation was measured below the unshielded bottom of a UV curing unit at one plant (2 seconds MPET). The proportion of UV radiation in different wavelength regions varied moderately (UVA, 38 to 56%; UVB 21 to 40%; and UVC, 12 to 24%). We conclude that UV curing units must be equipped with proper radiation shields, including the holes and fissures, and routinely checked and maintained in order to afford adequate protection from high intensity UV radiation at biologically hazardous wavelengths. Adequate eye and skin protection is required for workers during maintenance of unshielded equipment in order to prevent harmful effects.

Offshore stack-enclosed gas flares: Part II—Application and results

Stack-enclosed gas flares are used to flare the produced gas onboard offshore vessels. This paper presents results for the heat radiated from the hot gas plume to personnel on the deck of the vessel. A sensitivity study for the effect of relevant system parameters on heat radiation level shows that the most important effect is due to the product of the flow rate and the heating value of the gas. Three case studies were conducted for low, medium, and high capacity flares. Results are discussed with respect to limiting flare capacities. The calculated heat radiation levels were compared with allowable limits for continuous human exposure specified by the American Bureau of Shipping (ABS). The maximum heat radiation levels from the flare systems of the low and medium capacity cases were found to be well below the allowable limits. The maximum heat radiation at the flaring rate of 16·4 standard m 3/s (50 million standard ft 3/day) of the produced gas for the high capacity case was found to be below the allowable limit, but for 24·6 standard m 3/s (75 million standard ft 3/day) exceeds the limit significantly. It is shown that for this latter case, a modification in the design of the flare stack (e.g. increasing the window area for air entrance openings) brings the heat radiation to a level close to the allowable limit. However, increasing the window area for air entrance openings would increase the velocity of the air-gas mixture, which in turn would increase the flame length and, hence, the required stack length. Excessive increase in stack length may impose problems of vessel stability.

Ventilation of factory buildings by natural convection

A building with an arbitrary number of point and line heat sources at the floor is considered. Fresh air flows in the room through windows; warm air leaves through roof louvres. Above the heat sources there are turbulent plumes. At the walls adsorption of radiation from the heat sources gives rise to natural convection flows. To model the complicated flow field, the building is subdivided into several regions: (1) Turbulent plumes above the heat sources; (2) turbulent wall boundary layer; (3) fresh air region with temperature equal to ambient temperature; (4) discharge air region with constant temperature higher than ambient temperature. Mass, momentum and energy balances are set up for each region. In addition well-known results are used for turbulent plumes and wall boundary layers due to natural convection. The pressure drops across entrance and exit openings have to be compensated by buoyancy forces. Thus, the interface position, the mass flow and the temperature in the discharge air region can be determined. The influence of different parameters is discussed. The interface has to be above a certain level to guarantee appropriate working conditions.

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A Solution Cave in Gypsum

The main chamber of Alabaster Caverns, Woodward County, Oklahoma, has a capacious, nearly horizontal passageway about mile long, wholly in massive, coarsely crystalline gypsum. The cave possesses at least four features of phreatic origin, on which are superposed five other features of vadose origin. The similarity to such in entrance and exit openings, about i mile apart in a straight line, are in collapse sinkholes (ponors) that penetrate through the overlying Shimer gypsum member of the Blaine formation and the unnamed shaly member which separates the two gypsums. A smaller and horizontally less extensive chamber lies in the Shimer above the shale.