Numerical Simulation of the Bearing Capacity of Variotropic Short Concrete Beams Reinforced with Polymer Composite Reinforcing Bars.

One of the disadvantages of reinforced concrete is the large weight of structures due to the steel reinforcement. A way to overcome this issue and develop new types of reinforcing elements is by using polymer composite reinforcement, which can successfully compensate for the shortcomings of steel reinforcement. Additionally, a promising direction is the creation of variotropic (transversely isotropic) building elements. The purpose of this work was to numerically analyze improved short bending concrete elements with a variotropic structure reinforced with polymer composite rods and to determine the prospects for the further extension of the results obtained for long-span structures. Numerical models of beams of a transversally isotropic structure with various types of reinforcement have been developed in a spatially and physically nonlinear formulation in ANSYS software considering cracking and crashing. It is shown that, in combination with a stronger layer of the compressed zone of the beam, carbon composite reinforcement has advantages and provides a greater bearing capacity than glass or basalt composite. It has been proven that the use of the integral characteristics of concrete and the deflections of the elements are greater than those when using the differential characteristics of concrete along the height of the section (up to 5%). The zones of the initiation and propagation of cracks for different polymer composite reinforcements are determined. An assessment of the bearing capacity of the beam is given. A significant (up to 146%) increase in the forces in the reinforcing bars and a decrease in tensile stresses (up to 210-230%) were established during the physically non-linear operation of the concrete material. The effect of a clear redistribution of stresses is in favor of elements with a variotropic cross section in height.

OCTA and Functional Signs of Preclinical Retinopathy in Type 1 Diabetes Mellitus.

BACKGROUND AND OBJECTIVE: There is an emerging role for optical coherence tomography angiography (OCTA) in detecting microvasculature changes in diabetic retinopathy (DR). This study aimed to investigate visual functions and OCTA parameters of retinal and choriocapillaris (CC) flow in patients with type 1 diabetes mellitus (T1DM) without apparent DR. PATIENTS AND METHODS: Patients and age-matched healthy volunteers were enrolled. All participants underwent low-luminance visual acuity assessment, OCT, and OCTA. Assessed OCTA parameters included foveal avascular zone area, acircularity index, vessel density (VD), skeletonized density, and CC flow deficits. RESULTS: Low-luminance deficit (LLD) was significantly higher in patients with diabetes mellitus and correlated with skeletonized density and VD in the superficial vascular plexus (SVP). In the T1DM group, vessel density and skeletonized density were reduced in the SVP and deep capillary plexus. Flow deficits density and the mean size of the flow deficits were increased in patients with T1DM. CONCLUSION: Functional and microvasculature changes were observed at the preclinical stage of DR. Correlation of LLD and OCTA parameters can be a sign of early neurovascular impairment. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:S30-S34.].

Mobile Apps for Eye Care in Canada: An Analysis of the iTunes Store.

BACKGROUND: Mobile phone screens can facilitate stimulation to various components of the visual system and many mobile apps are accepted as a means of providing clinical assessments for the oculo-visual system. Although many of these apps are intended for use in clinical settings, there is a growing number of apps in eye care developed for self-tests and eye exercises for lay people. These and other features, however, have not yet been well described. OBJECTIVE: Our objective was to identify, describe, and categorize mobile apps related to eye care that are available to users in the Canadian iTunes market. METHODS: We conducted an extensive search of the Apple iTunes Store for apps related to eye care. We used the terms "eye," "eye care," "vision," and "eye test" and included apps that are targeted at both lay people and medical professionals. We excluded apps whose primary function is not related to eye care. Eligible apps were categorized by primary purpose, based on how they were described by their developers in the iTunes Store. RESULTS: Our search yielded 10,657 apps, of which 427 met our inclusion criteria. After removing duplicates, 355 unique apps were subject to further review. We assigned the eligible apps to three distinct categories: 39/355 apps (11.0%) were intended for use by medical professionals, 236 apps (66.5%, 236/355) were intended for use by lay people, and 80 apps (22.5%, 80/355) were intended for marketing eye care and eye-care products. We identified 9 subcategories of apps based on the descriptions of their primary functions. Apps for medical professionals fell into three subcategories: clinical calculators (n=6), clinical diagnostic tools (n=18), and education and networking apps for professionals (n=15). Apps for lay people fell into four subcategories: self-testing (n=153), eye exercises (n=30), patient tools and low vision aids (n=35), and apps for patient education (n=18). Mixed-use apps (n=80) were placed into two subcategories: marketing of individual practitioners or eye-care products (n=72) and marketing of multiple eye-care products or professional services. CONCLUSIONS: The most extensive subcategory pertaining to eye care consisted of apps for use by lay people, especially for conducting self-tests (n=236). This study revealed a previously uncharacterized category of apps intended for use by doctors and patients, of which the primary goal is marketing of eye-care services and products (n=80).