Artificial intelligence-based models for reconstructing the critical current and index-value surfaces of HTS tapes

For modelling superconductors, interpolation and analytical formulas are commonly used to consider the relationship between the critical current density and other electromagnetic and physical quantities. However, look-up tables are not available in all modelling and coding environments, and interpolation methods must be manually implemented. Moreover, analytical formulas only approximate real physics of superconductors and, in many cases, lack a high level of accuracy. In this paper, we propose a new approach for addressing this problem involving artificial intelligence (AI) techniques for reconstructing the critical surface of high temperature superconducting (HTS) tapes and predicting their index value known as n-value. Different AI models were proposed and implemented, relying on a public experimental database for electromagnetic specifications of HTS tapes, including artificial neural networks (ANN), eXtreme Gradient Boosting (XGBoost), and kernel ridge regressor (KRR). The ANN model was the most accurate in predicting the critical current of HTS materials, performing goodness of fit very close to 1 and extremely low root mean squared error. The XGBoost model proved to be the fastest method, with training computational times under 1 s; whilst KRR could be used as an alternative solution with intermediate performance

In vitro 2D and 3D roughness and spectrophotometric and gloss analyses of ceramic materials after polishing with different prophylactic pastes

Statement of problem: The effect of prophylactic polishing pastes on composite resin materials has been extensively investigated, but little is known about their effect on ceramic materials. Purpose: The purpose of this in vitro study was to evaluate the effect of prophylactic polishing pastes on the 2D and 3D roughness, translucency, and gloss of different ceramic materials. Material and methods: A total of 120 flat specimens (thickness: 2 mm) obtained from computer-aided design and computer-aided manufacturing (CAD-CAM) blocks of leucite glass-ceramic (Empress CAD), lithium disilicate glass-ceramic (e.max CAD), and zirconia (Zenostar MT) were glazed and sintered. Forty specimens from each material were then divided into 4 groups and polished with Cleanic fine, Nupro fine, or Proxyt fine pastes, leaving the control group untreated. The specimens were polished for 2 minutes with a prophylaxis cup mounted on a handpiece, applying a constant load of 3.9 N at 2000 rpm. Surface roughness was measured by using a contact profilometer and a 3D optical profilometer. The translucency parameter and gloss value were calculated by using a spectrophotometer and a glossmeter. One specimen per group was observed by scanning electron microscopy at 7200 magnification. Differences in means were compared by using 2-way ANOVA followed by the Tukey honestly significant difference (HSD) test (\u3b1=.05). Results: The 2D roughness of Empress was lower than that of e.max (P<.05) and was increased by using Cleanic fine and Nupro fine pastes (P<.05). The translucency parameter values of Empress and Zenostar decreased with the use of Nupro fine paste (P<.05). Zenostar showed the lowest translucency (P<.05). The effect of prophylactic polishing pastes on gloss was minimal (P>.05). The gloss of Empress was higher than that of Zenostar and e.max (P<.05). The Pearson correlation showed that gloss and surface roughness were correlated (P<.001). Conclusions: Polishing procedures can alter the surface of a ceramic restoration

Digital bar prototype technique for full-arch rehabilitation on implants

Background and Overview: The aim of the authors in this case report was to describe a new approach to using the digital bar prototype technique for complete digital full-arch implant rehabilitation. Two combinable structures were used during the same visit as prototypes to simultaneously test the implant locations and the prosthetic parameters. Then the structures were joined together to form the final prosthesis. Case Description: After the implant integration with the immediate provisional restoration, 3 sets of digital impressions were obtained to obtain a master digital model (MDM). A stereolithographic model with implant analogs was printed on the basis of the MDM. A titanium bar with implant connections and a functional resin structure were milled on the basis of the MDM and used as prototypes. To check the accuracy of the implant impression, the titanium prototype was tried in, and clinical and radiographic tests were performed. Then the resin prototype was slid into the positional prototype and fitted to the patient, and the esthetic and occlusal properties were evaluated and refined. Definitive restoration was obtained by luting the 2 prototypes together and finalizing the prosthesis with pink resin. Conclusions and Practical Implications: The prototypes allowed the clinician to simultaneously verify the accuracy of the digital impressions and test the prosthetic parameters in 1 visit. Moreover, they were used to create the final restoration. The digital bar prototype technique also allowed for the reduction of clinical and laboratory time in a full-arch rehabilitation on implants. Nevertheless, obtaining a full-arch impression in an edentulous arch can be challenging, and further studies are necessary to evaluate the long-term success of this technique

Effect of data leakage in brain MRI classification using 2D convolutional neural networks

In recent years, 2D convolutional neural networks (CNNs) have been extensively used to diagnose neurological diseases from magnetic resonance imaging (MRI) data due to their potential to discern subtle and intricate patterns. Despite the high performances reported in numerous studies, developing CNN models with good generalization abilities is still a challenging task due to possible data leakage introduced during cross-validation (CV). In this study, we quantitatively assessed the effect of a data leakage caused by 3D MRI data splitting based on a 2D slice-level using three 2D CNN models to classify patients with Alzheimer’s disease (AD) and Parkinson’s disease (PD). Our experiments showed that slice-level CV erroneously boosted the average slice level accuracy on the test set by 30% on Open Access Series of Imaging Studies (OASIS), 29% on Alzheimer’s Disease Neuroimaging Initiative (ADNI), 48% on Parkinson’s Progression Markers Initiative (PPMI) and 55% on a local de-novo PD Versilia dataset. Further tests on a randomly labeled OASIS-derived dataset produced about 96% of (erroneous) accuracy (slice-level split) and 50% accuracy (subject-level split), as expected from a randomized experiment. Overall, the extent of the effect of an erroneous slice-based CV is severe, especially for small datasets

Efficacy of different regimens of adjuvant radiochemotherapy for treatment of glioblastoma

Aims and background: We retrospectively analyzed the impact of different adjuvant chemotherapy regimens in a group of patients treated for glioblastoma compared to patients receiving only postoperative radiotherapy. Material and methods: Eighty-six consecutive patients underwent radiotherapy between January 2000 and December 2003: 52 patients received radiotherapy alone, 17 patients radiochemotherapy with low-dose temozolomide (20 mg/m(2)) + cyclooxygenase-2-inhibitors (200 mg), 6 patients radiochemotherapy with high-dose temozolomide (50 mg/m(2)). Eleven patients, with unfavorable prognostic factors, were treated with imatinib and 55/2.5 Gy. Results: The groups treated with high-and low-dose temozolomide showed the longest overall survival (median, 21 months and 17 months, respectively). Median overall survival was 9 months for radiation alone and 4 months for the imatinib-treated group. The same positive trend of temozolomide on prolonged overall survival was confirmed when only patients submitted to maximally radical resection or patients with KPS >70 were considered. Differences in progression-free survival were not statistically significant. Conclusions: Patients treated with adjuvant temozolomide either inside or outside of study protocols had survival times similar to other reports or randomized studies. The absence of a significant influence of temozolomide on progression-free survival could depend on the unavoidable drawbacks and biases of retrospective investigations or on the definition of relapse used. The unsatisfactory results of radiotherapy plus imatinib may have been due to a high prevalence of unfavorable prognostic factors in the respective patients. The ongoing controlled trial will further define the efficacy of adjuvant/concomitant imatinib