Calculation of tunnel incision parameters during phacoemulsification in patients with previous anterior radial keratotomy

Background. The purpose was the choice of the type of tunnel incision on the basis of mathematical calculations in cataract patients with a previous anterior radial keratotomy. Materials and methods. During the calculations, the formula for the chord length of a circle was used: L = 2R · sin(α/2), where R is the radius of the cornea, α is the angle (in degrees) between the two corneal incisions. The chord length was measured on the limbus (upper edge of the tunnel incision) and 2 mm from the limbus (lower edge of the tunnel incision). The chord 2 mm from the limbus is more important because the distance between kerato­tomy incisions at this site is smaller. From 0.4 to 1.0 mm must be added to the width of the knife blade, depending on the type of postoperative corneal healing, which will be the key to crossing the incisions. Results. The most common knives are those 2.2 mm long with a tunnel length of 2 mm. Therefore, we perform calculations based on this knife in patients with 8 and 12 keratotomy incisions and a corneal diameter of 12 mm vertically and 11 mm horizontally. In patients with 8 keratotomy incisions, a 2.2 mm knife can be used for a corneal tunnel incision, and in patients with 16 incisions, it is impossible to use a corneal tunnel. Conclusions. In cataract patients who have previously undergone anterior radial keratotomy, a special approach is needed to the choice of tunnel incision. The choice of access depends on the diameter of the cornea, the number of keratotomy incisions and the width of the knife and is calculated using the formula for the chord length of a circle.

Quantitative photogrammetric methodology for measuring mammalian belly score in the painted dog

The use of “belly scoring” can offer a novel, non-invasive objective management tool to gauge food intake between individuals, groups, and populations, and thus, population fitness. As food availability is increasingly affected by predation, ecological competition, climate change, habitat modification, and other human activities, an accurate belly scoring tool can facilitate comparisons among wildlife populations, serving as an early warning indicator of threats to wildlife population health and potential population collapse. In social species, belly scores can also be a tool to understand social behavior and ranking. We developed and applied the first rigorous quantitative photogrammetric methodology to measure belly scores of wild painted dogs (Lycaon pictus). Our methodology involves: (1) Rigorous selection of photographs of the dorso/lateral profile of individuals at a right angle to the camera, (2) photogrammetrically measuring belly chord length and “belly drop” in pixels, (3) adjusting belly chord length as a departure from a standardized leg angle, and (4) converting pixel measurements to ratios to eliminate the need to introduce distance from the camera. To highlight a practical application, this belly score method was applied to 631 suitable photographs of 15 painted dog packs that included 186 individuals, all collected between 2004–2015 from allopatric painted dog populations in and around Hwange (n = 462) and Mana Pools National Parks (n = 169) in Zimbabwe. Variation in mean belly scores exhibited a cyclical pattern throughout the year, corresponding to biologically significant patterns to include denning demand and prey availability. Our results show significant differences between belly scores of the two different populations we assessed, thus highlighting food stress in the Hwange population. In the face of growing direct and indirect anthropogenic disturbances, this standardised methodology can provide a rapid, species-specific non-invasive management tool that can be applied across studies to rapidly detect emergent threats.

Rotating Instabilities in a Low-Speed Single Compressor Rotor Row with Varying Blade Tip Clearance

When a compressor is throttled to the near stall point, rotating instability (RI) is often observed as significant increases of amplitude within a narrow frequency band which can be regarded as a pre-stall disturbance. In the current study, a single compressor rotor row with varying blade tip clearance (1.3%, 2.6% and 4.3% chord length) was numerically simulated using the zonal large eddy simulation model. The mesh with six blade passages was selected to capture the proper dynamic feature after being validated in comparison to the measured data, and the dynamic mode decomposition (DMD) approach was applied to the numerical temporal snapshots. In the experimental results, RIs are detected in the configurations with middle and large tip gaps (2.6% and 4.3% chord length), and the corresponding characterized frequencies are about 1/2 and 1/3 of the blade passing frequency, respectively. Simulations provide remarkable performance in capturing the measured flow features, and the DMD modes corresponding to the featured RI frequencies are successfully extracted and then visualized. The analysis of DMD results indicates that RI is essentially a presentation of the pressure wave propagating over the blade tip region. The tip leakage vortex stretches to the front part of the adjacent blade and consequently triggers the flow perturbations (waves). The wave influences the pressure distribution, which, in turn, determines the tip leakage flow and finally forms a loop.

Optimization of Wind Sail using Computational Fluid Dynamics Simulation

The marine industry is highly dependent on oil as the fuel and the increased consumption of this fast-depleting oil recourse creates a shortage of fuel for the future as well as pollutes the environment. The pollution of water bodies also seriously affects marine life. Thus, the need for an alternate sustainable fuel source is of great importance. One such feasible alternative energy source is wind energy. The abundance, free availability and ease of conversion make it an ideal alternative to oil. Wind energy can be extracted by wind turbines or by sails. The sails convert the wind energy directly into energy for propulsion. The challenge in the conversion is the relative angle of attack of wind on the sail. The wind cannot be expected to be always in the direction of the course of the ship. When the wind is at an angle to the direction of the course, the thrust in the course director will be reduced and a component of thrust is developed on the sail which shifts the course of the ship. Bringing the ship back to the original course will create an additional expenditure of fuel. In such circumstances modification of the sail section shape from its conventional form to an optimal form helps to reduce these deficiencies. Therefore, the effort here is to numerically analyze the aerodynamic characteristics of wing-sails and to optimize their shape. The aerofoil NACA 0018 used here was chosen through a high fidelity two-dimensional computational analysis which was done earlier. The tip of the NACA 0018 was further modified by tilting it through different angles and at different chord positions forming a flap. The main objective of the study is to optimize the angle and the position of the flap relative to the chord of the aerofoil. The flapped airfoils were formed by modifying them from 10% chord length to 60% chord length. That flap angle was also varied from 0 degrees to 50 degrees in steps of 10- deg. The angle of attack on the sail was varied from 0 to 10 degrees in steps of 2 degrees. The thrust in the direction of course and the lateral thrust of each of these sail sections were estimated, tabulated and graphs were plotted. Analyzing these, an optimum shape for the sail section is derived.

Prediction of Pore Volume Dispersion and Microstructural Characteristics of Concrete Using Image Processing Technique

Concrete has served an essential role in many infrastructural projects. Factors including pore percentage, pore distribution, and cracking affect concrete durability. This research aims to better understand pore size distribution in cement-based materials. Micro-computed tomography (micro-CT) pictures were utilised to characterise the interior structure of specimens without destroying them. The pore dispersion of the specimens was displayed in 3D, utilising the data and imaging techniques collected, and the pore volume dispersion was examined using a volume-based approach. Another way to describe heterogeneous pore features is the chord-length distribution, which was calculated from three-dimensional micro-CT scans and correlated with the traditional method. The collected specimens were subjected to physical and mechanical testing. In addition, image processing techniques were used to conduct the studies. The results showed that the chord-length distribution-based pore size distribution is very successful than the traditional volume-based technique. The acquired data could be used for research and to forecast the characteristics of the materials.

Experimental and model-based investigation of the links between snow bidirectional reflectance and snow microstructure

Snow stands out from materials at the Earth’s surface owing to its unique optical properties. Snow optical properties are sensitive to the snow microstructure, triggering potent climate feedbacks. The impacts of snow microstructure on its optical properties such as reflectance are, to date, only partially understood. However, precise modelling of snow reflectance, particularly bidirectional reflectance, are required in many problems, e.g. to correctly process satellite data over snow-covered areas. This study presents a dataset that combines bidirectional reflectance measurements over 500–2500 nm and the X-ray tomography of the snow microstructure for three snow samples of two different morphological types. The dataset is used to evaluate the stereological approach from Malinka (2014) that relates snow optical properties to the chord length distribution in the snow microstructure. The mean chord length and specific surface area (SSA) retrieved with this approach from the albedo spectrum and those measured by the X-ray tomography are in excellent agreement. The analysis of the 3D images has shown that the random chords of the ice phase obey the gamma distribution with the shape parameter m taking the value approximately equal to or a little greater than 2. For weak and intermediate absorption (high and medium albedo), the simulated bidirectional reflectances reproduce the measured ones accurately but tend to slightly overestimate the anisotropy of the radiation. For such absorptions the use of the exponential law for the ice chord length distribution instead of the one measured with the X-ray tomography does not affect the simulated reflectance. In contrast, under high absorption (albedo of a few percent), snow microstructure and especially facet orientation at the surface play a significant role in the reflectance, particularly at oblique viewing and incidence.

Wake Structures and Effect of Hydrofoil Shapes in Efficient Flapping Propulsion

In this work, direct numerical simulation (DNS) is used to investigate how airfoil shape affects wake structure and performance during a pitching-heaving motion. First, a class-shape transformation (CST) method is used to generate airfoil shapes. CST coefficients are then varied in a parametric study to create geometries that are simulated in a pitching and heaving motion via an immersed boundary method-based numerical solver. The results show that most coefficients have little effect on the propulsive efficiency, but the second coefficient does have a very large effect. Looking at the CST basis functions shows that the effect of this coefficient is concentrated near the 25% mark of the foils chord length. By observing the thrust force and hydrodynamic power through a period of motion it is shown that the effect of the foil shape change is realized near the middle of each flapping motion. Through further inspection of the wake structures, we conclude that this is due to the leading-edge vortex attaching better to the foil shapes with a larger thickness around 25% of the chord length. This is verified by the pressure contours, which show a lower pressure along the leading edge of the better performing foils. The more favorable pressure gradient generated allows for higher efficiency motion.

Chitin-Derived AVR-48 Prevents Experimental Bronchopulmonary Dysplasia (BPD) and BPD-Associated Pulmonary Hypertension in Newborn Mice

Bronchopulmonary dysplasia (BPD) is the most common complication of prematurity and a key contributor to the large health care burden associated with prematurity, longer hospital stays, higher hospital costs, and frequent re-hospitalizations of affected patients through the first year of life and increased resource utilization throughout childhood. This disease is associated with abnormal pulmonary function that may lead to BPD-associated pulmonary hypertension (PH), a major contributor to neonatal mortality and morbidity. In the absence of any definitive treatment options, this life-threatening disease is associated with high resource utilization during and after neonatal intensive care unit (NICU) stay. The goal of this study was to test the safety and efficacy of a small molecule derivative of chitin, AVR-48, as prophylactic therapy for preventing experimental BPD in a mouse model. Two doses of AVR-48 were delivered either intranasally (0.11 mg/kg), intraperitoneally (10 mg/kg), or intravenously (IV) (10 mg/kg) to newborn mouse pups on postnatal day (P)2 and P4. The outcomes were assessed by measuring total inflammatory cells in the broncho-alveolar lavage fluid (BALF), chord length, septal thickness, and radial alveolar counts of the alveoli, Fulton’s Index (for PH), cell proliferation and cell death by immunostaining, and markers of inflammation by Western blotting and ELISA. The bioavailability and safety of the drug were assessed by pharmacokinetic and toxicity studies in both neonatal mice and rat pups (P3-P5). Following AVR-48 treatment, alveolar simplification was improved, as evident from chord length, septal thickness, and radial alveolar counts; total inflammatory cells were decreased in the BALF; Fulton’s Index was decreased and lung inflammation and cell death were decreased, while angiogenesis and cell proliferation were increased. AVR-48 was found to be safe and the no-observed-adverse-effect level (NOAEL) in rat pups was determined to be 100 mg/kg when delivered via IV dosing with a 20-fold safety margin. With no reported toxicity and with a shorter half-life, AVR-48 is able to reverse the worsening cardiopulmonary phenotype of experimental BPD and BPD-PH, compared to controls, thus positioning it as a future drug candidate.