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EXPERIMENTAL AND NUMERICAL INVESTIGATION OF RAILRAOD VEHICLE BRAKING DYNAMICS

One of the important issues associated with the use of trajectory coordinates in railroad vehicle dynamic algorithms is the ability of such coordinates to deal with braking and traction scenarios. In these algorithms, track coordinate systems that travel with constant speeds are introduced. As a result of using a prescribed motion for these track coordinate systems, the simulation of braking and/or traction scenarios becomes difficult or even impossible. The assumption of the prescribed motion of the track coordinate systems can be relaxed, thereby allowing the trajectory coordinates to be effectively used in modelling braking and traction dynamics. One of the objectives of this investigation is to demonstrate that by using track coordinate systems that can have an arbitrary motion, the trajectory coordinates can be used as the basis for developing computer algorithms for modelling braking and traction conditions. To this end, a set of six generalized trajectory coordinates is used to define the configuration of each rigid body in the railroad vehicle system. This set of coordinates consists of an arc length that represents the distance travelled by the body, and five relative coordinates that define the configuration of the body with respect to its track coordinate system. The independent non-linear state equations of motion associated with the trajectory coordinates are identified and integrated forward in time in order to determine the trajectory coordinates and velocities. The results obtained in this study show that when the track coordinate systems are allowed to have an arbitrary motion, the resulting set of trajectory coordinates can be used effectively in the study of braking and traction conditions. The results obtained using the trajectory coordinates are compared with the results obtained using the absolute Cartesian-coordinate-based formulations, which allow modelling braking and traction dynamics. In addition to this numerical validation of the trajectory coordinate formulation in braking scenarios, an experimental validation is also conducted using a roller test rig. The comparison presented in this study shows a good agreement between the obtained experimental and numerical results

Keratoconus progression in patients with allergy and elevated surface matrix metalloproteinase 9 Point-of-Care Test

PURPOSE: To assess keratoconus (KC) progression in patients with allergies who also tested positive to surface matrix metalloproteinase 9 (MMP-9) point-of-care test. METHODS: Prospective comparative study including 100 stage I-II keratoconic patients, mean age 16.7±4.6 years. All patients underwent an anamnestic questionnaire for concomitant allergic diseases and were screened with the MMP-9 point-of-care test. Patients were divided into two groups: patients KC with allergies (KC AL) and patients KC without allergies (KC NAL). Severity of allergy was established by papillary subtarsal response grade and KC progression assessed by Scheimpflug corneal tomography, corrected distance visual acuity (CDVA) measurement in a 12-month follow-up. RESULTS: The KC AL group included 52 patients and the KC NAL group 48. In the KC AL group, 42/52 of patients (81%) were positive to MMP-9 point-of-care test versus two positive patients in the KC NAL group (4%). The KC AL group data showed a statistically significant decrease of average CDVA, from 0.155±0.11 to 0.301±0.2 logarithm of the minimum angle of resolution (P<0.005) at 12 months; Kmax value increased significantly, from 50.2 D±2.7 to 55.2 D±1.9 on average. The KC NAL group revealed a slight KC progression without statistically significant changes. Pearson correlation test showed a high correlation between Kmax worsening and severity of PSR in the KC AL group. CONCLUSIONS: The study demonstrated a statistically significant progression of KC in patients with concomitant allergies, positive to MMP-9 point-of-care test versus negative. A high correlation between severity of allergy and KC progression was documented

Are adverse events related to the completeness of clinical records? Results from a retrospective records review using the Global Trigger Tool

Clinical record (CR) is a tool for recording details about the patient and the most commonly used source of information for detecting adverse events (AEs). Its completeness is an indicator of the quality of care provided and may provide clues for improving professional practice. The primary aim of this study was to estimate the prevalence of AEs. The secondary aims were to determine the completeness of CRs and to examine the relationship between the two variables. We retrospectively reviewed randomly selected CRs of patients discharged from the Academic Hospital of Udine (Italy) in the departments of general surgery, internal medicine, and obstetrics between July and September 2020. Evaluation was performed using the Global Trigger Tool and a checklist to evaluate the completeness of CRs. The relationship between the occurrence of AEs and the completeness of CRs was analyzed using nonparametric tests. A binomial logistic regression analysis was also performed. We reviewed 291 CRs and identified 368 triggers and 56 AEs. Among them, 16.2% of hospitalizations were affected by at least one AE, with a higher percentage in general surgery. The most common AEs were surgical injuries (42.6%; 24) and care related (26.8%; 15). A significant positive correlation was found between the length of hospital stay and the number of AEs. The average completeness of CRs was 72.9% and was lower in general surgery. The decrease in CR completeness correlated with the increase in the total number of AEs (R = -0.14; P = .017), although this was not confirmed by regression analysis by individual departments. Our results seem to suggest that completeness of CRs may benefit patient safety, so ongoing education and involvement of health professionals are needed to maintain professional adherence to CRs