Graphical modeling for item difficulty in medical faculty exams

Background: There are different indexes used in the evaluation of exam results. One important index is the difficulty level of the item that is also used in this study to obtain control charts. This article offers  some suggestions for the improvement of multiple-choice tests using item analysis statistics.Materials and Methods: The graphical modeling is important for the rapid and comparative evaluation of test results. The control chart is a tool that can be used to sharpen our teaching and testing skills by inspecting the weaknesses of measurements and producing reliable items. The research data for the application of control charts were obtained using the results of the fourth and fifth.grade studentfs exams at Ondokuz Mayis University, Faculty of Medicine. I.chart or moving range chart (MR) is preferred for whole variable data.Results: It is seen that all observations are within control limits for I.chart, but three points on MR.chart are settled on the LCL. Using x̄-chart with subgroups, it was determined that control measurements were within the upper and lower limits in both charts. The difficulty levels of items were examined by obtaining different variable control charts. The difficulty level of the two items exceeded the upper control limit in R-and S-charts.Conclusion: The control charts have the advantage for classifying items as acceptable or unacceptable based on item difficulty criteria.Key words: Item difficulty, quality control, statistical process control, variable control chart

Label-Free Nanometer-Resolution Imaging of Biological Architectures through Surface Enhanced Raman Scattering

Label free imaging of the chemical environment of biological specimens would readily bridge the supramolecular and the cellular scales, if a chemical fingerprint technique such as Raman scattering can be coupled with super resolution imaging. We demonst

Label-free nanometer-resolution imaging of biological architectures through surface enhanced raman scattering

Label free imaging of the chemical environment of biological specimens would readily bridge the supramolecular and the cellular scales, if a chemical fingerprint technique such as Raman scattering can be coupled with super resolution imaging. We demonstrate the possibility of label-free super-resolution Raman imaging, by applying stochastic reconstruction to temporal fluctuations of the surface enhanced Raman scattering (SERS) signal which originate from biomolecular layers on large-area plasmonic surfaces with a high and uniform hot-spot density (>1011/cm2, 20 to 35 nm spacing). A resolution of 20 nm is demonstrated in reconstructed images of self-assembled peptide network and fibrilated lamellipodia of cardiomyocytes. Blink rate density is observed to be proportional to the excitation intensity and at high excitation densities (>10 kW/cm2) blinking is accompanied by molecular breakdown. However, at low powers, simultaneous Raman measurements show that SERS can provide sufficient blink rates required for image reconstruction without completely damaging the chemical structure

Microsurgery can cure most intracranial dural arteriovenous fistulae of the sinus and non-sinus type

There is consensus that intracranial dural arteriovenous fistulae (dAVF) with direct (non-sinus-type) or indirect (sinus-type) retrograde filling of a leptomeningeal vein should be treated due to the high risk of neurological deficits and hemorrhage. No consensus exists on treatment modality (surgery and/or embolization) and, if surgery is performed, on the best surgical strategy. This series aims to evaluate the role of surgery in the management of aggressive dAVFs. Forty-two patients underwent surgery. Opening and packing the sinus with thrombogenic material was performed in 9 of the 12 sinus-type dAVFs. In two sinus-type fistulae of the cavernous sinus and 1 of the torcular, microsurgery was used as prerequisite for subsequent embolization by providing access to the sinus. In the 30 non-sinus-type dAVFs, surgery consisted of interruption of the draining vein at the intradural entry point. In 41 patients undergoing 43 operations, elimination of the dAVF was achieved (97.6%). In one case, a minimal venous drainage persisted after surgery. The transient surgical morbidity was 11.9% (n = 5) and the permanent surgical morbidity 7.1% (n = 3). Our surgical strategy was to focus on the arterialized leptomeningeal vein in the non-sinus-type and on the arterialized sinus segment in the sinus-type dAVFs allowing us to obliterate all but one dAVF with a low morbidity rate. We therefore propose that microsurgery should be considered early in the treatment of both types of aggressive dAVFs. In selected cases of cavernous sinus dAVFs, the role of microsurgery is reduced to that of an adjunct to endovascular therapy

Co-infection and ICU-acquired infection in COIVD-19 ICU patients: a secondary analysis of the UNITE-COVID data set

Background: The COVID-19 pandemic presented major challenges for critical care facilities worldwide. Infections which develop alongside or subsequent to viral pneumonitis are a challenge under sporadic and pandemic conditions; however, data have suggested that patterns of these differ between COVID-19 and other viral pneumonitides. This secondary analysis aimed to explore patterns of co-infection and intensive care unit-acquired infections (ICU-AI) and the relationship to use of corticosteroids in a large, international cohort of critically ill COVID-19 patients.Methods: This is a multicenter, international, observational study, including adult patients with PCR-confirmed COVID-19 diagnosis admitted to ICUs at the peak of wave one of COVID-19 (February 15th to May 15th, 2020). Data collected included investigator-assessed co-infection at ICU admission, infection acquired in ICU, infection with multi-drug resistant organisms (MDRO) and antibiotic use. Frequencies were compared by Pearson's Chi-squared and continuous variables by Mann-Whitney U test. Propensity score matching for variables associated with ICU-acquired infection was undertaken using R library MatchIT using the "full" matching method.Results: Data were available from 4994 patients. Bacterial co-infection at admission was detected in 716 patients (14%), whilst 85% of patients received antibiotics at that stage. ICU-AI developed in 2715 (54%). The most common ICU-AI was bacterial pneumonia (44% of infections), whilst 9% of patients developed fungal pneumonia; 25% of infections involved MDRO. Patients developing infections in ICU had greater antimicrobial exposure than those without such infections. Incident density (ICU-AI per 1000 ICU days) was in considerable excess of reports from pre-pandemic surveillance. Corticosteroid use was heterogenous between ICUs. In univariate analysis, 58% of patients receiving corticosteroids and 43% of those not receiving steroids developed ICU-AI. Adjusting for potential confounders in the propensity-matched cohort, 71% of patients receiving corticosteroids developed ICU-AI vs 52% of those not receiving corticosteroids. Duration of corticosteroid therapy was also associated with development of ICU-AI and infection with an MDRO.Conclusions: In patients with severe COVID-19 in the first wave, co-infection at admission to ICU was relatively rare but antibiotic use was in substantial excess to that indication. ICU-AI were common and were significantly associated with use of corticosteroids

Clinical and organizational factors associated with mortality during the peak of first COVID-19 wave: the global UNITE-COVID study

Purpose: To accommodate the unprecedented number of critically ill patients with pneumonia caused by coronavirus disease 2019 (COVID-19) expansion of the capacity of intensive care unit (ICU) to clinical areas not previously used for critical care was necessary. We describe the global burden of COVID-19 admissions and the clinical and organizational characteristics associated with outcomes in critically ill COVID-19 patients. Methods: Multicenter, international, point prevalence study, including adult patients with SARS-CoV-2 infection confirmed by polymerase chain reaction (PCR) and a diagnosis of COVID-19 admitted to ICU between February 15th and May 15th, 2020. Results: 4994 patients from 280 ICUs in 46 countries were included. Included ICUs increased their total capacity from 4931 to 7630 beds, deploying personnel from other areas. Overall, 1986 (39.8%) patients were admitted to surge capacity beds. Invasive ventilation at admission was present in 2325 (46.5%) patients and was required during ICU stay in 85.8% of patients. 60-day mortality was 33.9% (IQR across units: 20%–50%) and ICU mortality 32.7%. Older age, invasive mechanical ventilation, and acute kidney injury (AKI) were associated with increased mortality. These associations were also confirmed specifically in mechanically ventilated patients. Admission to surge capacity beds was not associated with mortality, even after controlling for other factors. Conclusions: ICUs responded to the increase in COVID-19 patients by increasing bed availability and staff, admitting up to 40% of patients in surge capacity beds. Although mortality in this population was high, admission to a surge capacity bed was not associated with increased mortality. Older age, invasive mechanical ventilation, and AKI were identified as the strongest predictors of mortality

The management of cubitus varus and valgus using the Ilizarov method

Cubitus varus and valgus are the most common complications of supracondylar and lateral condylar fractures. Various combinations of osteotomy and fixation have been described to correct these deformities but each is associated with significant complications. In this study, we used distraction osteogenesis and Ilizarov frame fixation to treat 24 elbows in 23 patients with cubitus varus or valgus. Their clinical outcome was evaluated using the protocol of Bellemore et al. The mean time to follow-up was 18.3 months (10 to 36) and the mean time to frame removal was 13.5 weeks (8 to 20). The mean carrying angle was corrected from -18.7 degrees (-10 degrees to -30 degrees) to 6.1 degrees (2 degrees to 10 degrees) in patients with cubitus varus and from 36.5 degrees (25 degrees to 45 degrees) to 9.4 degrees (4 degrees to 15 degrees) in patients with cubitus valgus. There were 18 excellent and six good results

Item analysis and evaluation in the examinations in the faculty of medicine at Ondokuz Mayis University

Background: Item analysis is an effective method in the evaluation of multiple‑choice achievement tests. This study aimed to compare the classical and the latent class models used in item analysis, as well as their efficacy in the evaluation of the examinations of the medical faculty.Materials and Methods: The achievement tests in the medical faculty were evaluated using different methods. The two methods used were the classical and the latent class models. Among the classical methods, Cronbach’s alpha, split half methods, item discrimination, and item difficulty was investigated. On the other hand, various models of item response theory (IRT) and their statistics were compared in the group of latent class methods.Results: Reliability statistics had values above 0.87. Item no. 7 was found easy, item no. 45 difficult and item no. 64 fairly difficult according to the evaluations done by classical and item response theories. In terms of item discrimination, item no. 45 had lower, item no. 7 had middle and item no. 64 had high discrimination levels. The distribution graph shows that personal abilities are good enough to tick the correct choice.Conclusion: In this study, similar results were obtained by classical and latent methods. IRT can be considered perfect at a mathematical level, and if its assumptions are satisfied, it can easily perform assessments and measurements for most types of complex problems. Classical theory is easy to understand and to apply, while IRT is, on the contrary, sometimes rather difficult to understand and to implement.Key words: Classical test theory, item analysis, item difficulty, item discrimination, item response theory, reliabilit

Treatment of intertrochanteric fractures in geriatric patients with a modified external fixator

Forty-two geriatric patients who had an intertrochanteric fracture were treated with a semicircular modification of the Ilizarov frame designed by Cattaneo and Catagni between January 1997 and September 2001. Twenty-five of the patients were female, 17 mate. The average age of the patients was 77.5 years (range, 63-99). No intraoperative complication occurred. Deep pin-track infection was found in four patients and varus deformity was observed in two patients and shortening of less than 2 cm in 10 patients. Fixator removal was achieved in a mean time of 12 weeks (range, 10-18). No implant failure, refracture or stiffness of knee and hip joint movements was recorded. We concluded that the treatment of intertrochanteric fractures of the elderly patients with our modification provides significant advantages such as minimal operative and anaesthetic risks, no blood loss, early weight-bearing, short hospitalisation time and rapid union time. (c) 2004 Elsevier Ltd. All rights reserved

Treatment of humeral shaft non-unions by the Ilizarov method

Thirty-five humeral shaft non-unions treated by the Ilizarov external fixator were studied after an average of 39 months. Bone union was achieved in all but one. The mean time to union was 5.5 months (range: 3-10 months). Major pin tract problems leading to removal of the Schanz screws occurred in three patients. A. radial nerve palsy developed in three patients, two recovered spontaneously and one was treated with a triple tendon transfer