Optimal correction of infeasible equations system as Ax + B|x|= b using ℓ p-norm regularization

Optimal correction of an infeasible equations system as Ax + B|x|= b leads into a non-convex fractional problem. In this paper, a regularization method(ℓp-norm, 0 < p < 1), is presented to solve mentioned fractional problem. In this method, the obtained problem can be formulated as a non-convex and nonsmooth optimization problem which is not Lipschitz. The objective function of this problem can be decomposed as a difference of convex functions (DC). For this reason, we use a special smoothing technique based on DC programming. The numerical results obtained for generated problem show high performance and the effectiveness of the proposed method.

Comparative characteristics of changes in visual acuity according to test lighting in healthy people and in patients with myopia

The objective of the work consisted of comparing the characteristics of the changes in visual acuity as a function of the illumination of the tests in healthy individuals and in patients with myopia, examining two groups (50 people each): a control group of healthy individuals and patients with high myopia with visual acuity with optimal correction above 1.0. Visual acuity was determined under different lighting conditions (from 50Lx to 400Lx) using optotype tables with a small step of 0.05, and increasing the function δ, which is the difference between these values. δ in healthy individuals is 0.7, and in individuals with myopia it is equal to 0.55, which is a fairly high indicator and confirms the absence of contraindications to attract this category of patients to various types of visually strenuous work, including driving.

Occipitofrontal switch for correction of anterior plagiocephaly planned through virtual mock surgery

Background: Unilateral coronal synostosis causing anterior plagiocephaly can result in restricted brain development and severe facial deformities. Various surgical procedures have been described for the correction of this deformity. Cranial vault remodeling, however, is associated with several complications. Occipitofrontal switching is a novel technique which utilizes a part of the contralateral occipital bone to reconstruct the frontal area. This is the first such case reported from India and first report where virtual mock surgery has been utilized for precision and improving outcome in this elegant procedure. Case Description: A 5-year-old girl presented with left anterior plagiocephaly. 3D image of her skull was reconstructed using Geomagic Freeform software (3D Systems, Rock Hill, SC). Measurements were accurately drawn and the procedure was practised virtually before performing the occipitofrontal switch on the patient. There were minimal blood loss and postoperative morbidity. One year follow-up of the patient showed optimal correction of the defect in the forehead region, symmetrical shape of the frontal and occipital region and symmetrical brows. Conclusion: The technique of occipitofrontal switch for correction of anterior plagiocephaly is an elegant procedure with good functional and aesthetic outcome.

TAKE THE RISK OR LOSE THE CHANCE!

The hallmark of keratoconus is central or paracentral stromal thinning, accompanied by apical protrusion and irregular astigmatism. Patients typically experience variable reductions in visual acuity, image distortion, and increased sensitivity to glare and light. The latter becomes of major interest when patients with keratoconus present with a cataract which contributes to a further visual decline. PURPOSE: To present a case report of a patient who underwent cataract surgery, with implantation of an intraocular implant called pinhole and correction of an irregular corneal astigmatism as a result of keratoconus. METHODS: A report of a rare case, the first implantation of XtraFocus implant in Bulgaria for the correction of keratoconus combined with cataract. RESULTS: All necessary measurements were performed using an iTrace aberrometer and IOL Master 700. The cataract removal was performed by standard phacoemulsification followed by implantation of a pinhole implant in the capsular bag. No complications related to the position of the implant were observed in the postoperative period. Optimal correction of the distance vision and near vision was achieved, and the results were monitored within six months after surgery. CONCLUSION: The pinhole implant was securely positioned in the capsular bag. Well tolerated by the patient, the implant played a key role in effectively overcoming the irregular corneal astigmatism. There is a significant improvement in visual acuity with results satisfying the patient's high expectations.

C7 extension crosswise osteotomy: a novel osteotomy for correction of chin-on-chest deformity in a patient with ankylosing spondylitis

Extension crosswise osteotomy at C7 (C7 ECO) was developed for the correction of forward gaze in patients with chin-on-chest deformity due to ankylosing spondylitis. A modification of cervicothoracic extension osteoclasis (C/T EO), C7 ECO replaces osteoclasis of the anterior column with a crosswise cut of the C7 vertebral body to eliminate the risks of unintended dislocation of the cervical spine. C7 ECO also eliminates the risks of C7 and T1 pedicle subtraction osteotomies (C/T PSOs), in which a posteriorly based wedge excision may lead to stretching injuries of the lower cervical roots and/or failure to achieve the exact angle of excision required for an optimal correction. Furthermore, opening the osteotomy anteriorly, as in the authors’ method, instead of closing it posteriorly, as in PSO, eliminates the risks related to shortening of the posterior column, such as buckling of the dura, kinking of the spinal cord, and stretching of the lower cervical nerve roots. Here, the authors report the use of C7 ECO for the surgical treatment of a 69-year-old man with severe compromise of his forward gaze due to chin-on-chest deformity in the course of ankylosing spondylitis. After uneventful correction surgery, the patient regained the ability to see objects, namely faces of people, at the level of his head while standing and to perform work tasks at a desk.

Application of Machine Learning for the in-Field Correction of a PM2.5 Low-Cost Sensor Network

Many low-cost sensors (LCSs) are distributed for air monitoring without any rigorous calibrations. This work applies machine learning with PM2.5 from Taiwan monitoring stations to conduct in-field corrections on a network of 39 PM2.5 LCSs from July 2017 to December 2018. Three candidate models were evaluated: Multiple linear regression (MLR), support vector regression (SVR), and random forest regression (RFR). The model-corrected PM2.5 levels were compared with those of GRIMM-calibrated PM2.5. RFR was superior to MLR and SVR in its correction accuracy and computing efficiency. Compared to SVR, the root mean square errors (RMSEs) of RFR were 35% and 85% lower for the training and validation sets, respectively, and the computational speed was 35 times faster. An RFR with 300 decision trees was chosen as the optimal setting considering both the correction performance and the modeling time. An RFR with a nighttime pattern was established as the optimal correction model, and the RMSEs were 5.9 ± 2.0 μg/m3, reduced from 18.4 ± 6.5 μg/m3 before correction. This is the first work to correct LCSs at locations without monitoring stations, validated using laboratory-calibrated data. Similar models could be established in other countries to greatly enhance the usefulness of their PM2.5 sensor networks.