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Improving Pediatric Low-Grade Neuroepithelial Tumors Molecular Subtype Identification Using a Novel AUROC Loss Function for Convolutional Neural Networks

arXiv

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arXiv 2024年

作者： Namdar, Khashayar Wagner, Matthias W. Hawkins, Cynthia Tabori, Uri Ertl-Wagner, Birgit B. Khalvati, Farzad TorontoON Canada Neurosciences & Mental Health Research Program SickKids Research Institute TorontoON Canada Department of Medical Imaging University of Toronto TorontoON Canada Institute of Medical Science University of Toronto TorontoON Canada Department of Diagnostic and Interventional Neuroradiology University Hospital Augsburg Germany Department of Paediatric Laboratory Medicine Division of Pathology The Hospital for Sick Children University of Toronto Canada Department of Neurooncology The Hospital for Sick Children TorontoON Canada Department of Computer Science University of Toronto TorontoON Canada Department of Mechanical and Industrial Engineering University of Toronto TorontoON Canada Vector Institute TorontoON Canada

Pediatric Low-Grade Neuroepithelial Tumors (PLGNT) are the most common pediatric cancer type, accounting for 40% of brain tumors in children, and identifying PLGNT molecular subtype is crucial for treatment planning. However, the gold standard to determine the PLGNT subtype is biopsy, which can be impractical or dangerous for patients. This research improves the performance of Convolutional Neural Networks (CNNs) in classifying PLGNT subtypes through MRI scans by introducing a loss function that specifically improves the model's Area Under the Receiver Operating Characteristic (ROC) Curve (AUROC), offering a non-invasive diagnostic alternative. In this study, a retrospective dataset of 339 children with PLGNT (143 BRAF fusion, 71 with BRAF V600E mutation, and 125 non-BRAF) was curated. We employed a CNN model with Monte Carlo random data splitting. The baseline model was trained using binary cross entropy (BCE), and achieved an AUROC of 86.11% for differentiating BRAF fusion and BRAF V600E mutations, which was improved to 87.71% using our proposed AUROC loss function (p-value 0.045). With multiclass classification, the AUROC improved from 74.42% to 76.59% (p-value 0.0016). Copyright © 2024, The Authors. All rights reserved.

关键词： Pediatrics

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Numerical study of piezoelectric energy harvester utilizing motorcycle vibrations

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AIP Conference Proceedings 2024年第1期3215卷

作者： Mujahid Abdurrahim Radon Dhelika Mohammad Akita Indianto Mechanical Engineering Department Faculty of Engineering Universitas Indonesia Kampus Baru UI Depok Indonesia 16424 Energy Systems Engineering Graduate Program Faculty of Engineering Universitas Indonesia Kampus Baru UI Depok Indonesia 16424 Tropical Renewable Energy Center Faculty of Engineering Universitas Indonesia Kampus Baru UI Depok Indonesia 16424

A numerical study of the piezoelectric energy harvester is performed to see its visibility for application in harvesting motorcycle vibration. The target vibration of 40-70 Hz is the requirement as it is the frequent vibration during motorcycle operations. A composite cantilever structure of SU-8/Al/PVDF/Al is set as the main body of the structure with a thickness of 200/0.3/5/0.3 µm. The length is set as the study point to see the suitable structure for the application. The study found that by designing the correct length, the cantilever’s resonance frequency can match the target vibration frequency; on the other hand longer cantilever results in higher deflection and energy generation of the piezoelectric structure. The study concludes that the length of 33 mm is suitable for covering the 40-70 Hz target vibration with a resonance frequency of 54.3 Hz. The voltage generated is 24.8 mV. This finding is one important step to developing an energy harvester device that can be used in wide applications.

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A unified bi-directional model for natural and artificial trust in human-robot collaboration

arXiv

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arXiv 2021年

作者： Azevedo-Sa, Hebert Yang, X. Jessie Robert, Lionel P. Tilbury, Dawn M. Robotics Institute University of Michigan Ann ArborMI48109 United States Department of Industrial and Operations Engineering University of Michigan Ann Arbor United States School of Information University of Michigan Ann Arbor United States Department of Mechanical Engineering University of Michigan Ann Arbor United States

We introduce a novel capabilities-based bidirectional multi-task trust model that can be used for trust prediction from either a human or a robotic trustor agent. Tasks are represented in terms of their capability requirements, while trustee agents are characterized by their individual capabilities. Trustee agents' capabilities are not deterministic;they are represented by belief distributions. For each task to be executed, a higher level of trust is assigned to trustee agents who have demonstrated that their capabilities exceed the task's requirements. We report results of an online experiment with 284 participants, revealing that our model outperforms existing models for multi-task trust prediction from a human trustor. We also present simulations of the model for determining trust from a robotic trustor. Our model is useful for control authority allocation applications that involve human-robot teams. © 2021, CC BY-NC-ND.

关键词： robotics

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Development of structural type mortars reinforced with corn fiber (Zea Mays)

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Journal of engineering Science and Technology Review 2019年第4期12卷 69-77页

作者： Monsalve, Mónica Higuera, Oscar Estrada, Pedro Orozco, Marlyn Pedraza, Cristian Department of Mechanical and Mechatronic Engineering National University of Colombia Cr 45 # 26-85 Bogotá Colombia CONFORMAT Research Group Mechanical Engineering program University of Atlántico Km 7 Antigua vía Puerto Colombia Colombia

In this investigation, structural type mortars reinforced with corn fibers were elaborated;these fibers were previously treated with flaxseed oil and paraffin, cut to lengths of 1, 2 and 5 cm, and weighed, in order to obtain a ratio of 0.5% and 1% by weight with respect to the quantity of cement. The fibers were physic chemically characterized by Thermogravimetric Analysis (TGA), Derivative Thermogravimetry (DTG) and Fourier Transform Infrared Spectrometry (FTIR), and their chemical resistance was evaluated by exposing them to a concentrated solution of Ca(OH)2 that simulated the alkaline medium of the cement. The fiber-reinforced mortars were mechanically characterized by compression and bending tests, which were performed 7, 21 and 28 days after processing. The results show that after 28 days the paraffin-coated corn fiber reinforced mortars, with 1 cm in length and 0.5% in weight presented the best results, an increase in the compressive and flexural strength of 16.92% and 38.51% respectively was noted, compared to the unreinforced mortar. © 2019 School of Science, IHU.

关键词： Bending strength

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Left Atrial Appendage Occlusion: Current Stroke Prevention Strategies and a Shift Toward Data-Driven, Patient-Specific Approaches

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Journal of the Society for Cardiovascular Angiography and Interventions 2022年第5期1卷 100405-100405页

作者： Mendez, Keegan Kennedy, Darragh G. Wang, Dee Dee Roche, Ellen T. Harvard/MIT Health Sciences and Technology Program Massachusetts Institute of Technology Cambridge MA United States Institute for Medical Engineering and Science Massachusetts Institute of Technology Cambridge MA United States Department of Biomedical Engineering Columbia University New York NY United States Henry Ford Health Detroit MI United States Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge MA United States

The left atrial appendage (LAA) is a complex structure with unknown physiologic function protruding from the main body of the left atrium. In patients with atrial fibrillation, the left atrium does not contract effectively. Insufficient atrial and LAA contractility predisposes the LAA morphology to hemostasis and thrombus formation, leading to an increased risk of cardioembolic events. Oral anticoagulation therapies are the mainstay of stroke prevention options for patients;however, not all patients are candidates for long-term oral anticoagulation. Percutaneous occlusion devices are an attractive alternative to long-term anticoagulation therapy, although they are not without limitations, such as peri-implant leakage and device-related thrombosis. Although efforts have been made to reduce these risks, significant interpatient heterogeneity inevitably yields some degree of device-anatomy mismatch that is difficult to resolve using current devices and can ultimately lead to insufficient occlusion and poor patient outcomes. In this state-of-the-art review, we evaluated the anatomy of the LAA as well as the current pathophysiologic understanding and stroke prevention strategies used in the management of the risk of stroke associated with atrial fibrillation. We highlighted recent advances in computed tomography imaging, preprocedural planning, computational modeling, and novel additive manufacturing techniques, which represent the tools needed for a paradigm shift toward patient-centric LAA occlusion. Together, we envisage that these techniques will facilitate a pipeline from the imaging of patient anatomy to patient-specific computational and bench-top models that enable customized, data-driven approaches for LAA occlusion that are engineered specifically to meet each patient's unique needs. © 2022 The Authors

关键词： computed tomography imaging left atrial appendage left atrial appendage occlusion stroke

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Comparative study on mechanical characteristics of functionally graded and Coreshell nanospheres: An atomistic approach

arXiv

引用

arXiv 2021年

作者： Malakar, Prottay Anan, Md Al Rifat Islam, Mahmudul Thakur, Md Shajedul Hoque Mojumder, Satyajit Department of Mechanical Engineering Bangladesh University of Engineering and Technology Dhaka1000 Bangladesh Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States Theoretical and Applied Mechanics Program Northwestern University EvanstonIL60208 United States

Functionally Graded Material (FGM) is a type of advanced material consisting of two (or more) distinct substances with a constantly changing composition profile. FGM technologies have moved from their traditional use to advanced micro and nanoscale electronics and energy conversion systems along with the advent of nanotechnology. MD simulations are used in this analysis to examine the effect of compressive load on Ag-Au FGM and Coreshell nanospheres. The plasticity process is often started by the nucleation of partial dislocations from the contact surfaces, and these dislocations spread towards the nanosphere’s center. Also, we have found the formation of pyramidal-shaped partial dislocations on the pseudo-plastic regime. For a given wt% range of Ag in Au, Coreshell nanospheres have stronger mechanical strength than FGM nanospheres, and we have also observed two distinct patterns in ultimate stress variation for FGM and Coreshell nanospheres. The dislocation analysis suggests a correlation between this stress variation and the Shockley & Hirth partial dislocation density. © 2021, CC BY.

关键词： Nanospheres

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Heat treatment effects and grain refinement analysis on hypoeutectic Al-Si alloys

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AIP Conference Proceedings 2022年第1期2527卷

作者： Baskaran Jaganathan Suresh Mylsamy Satish Selvaraj Gowtham Govindaraj Balaadithiyan Ponniah Gokulnath Saraboji 1Department of Mechanical Engineering Sri Krishna College of Engineering and Technology Coimbatore Tamilnadu India 2Department of Robotics and Automation Engineering PSG College of Technology Coimbatore Tamilnadu India 3Department of Mechanical Engineering Sri Ramakrishna Engineering College Coimbatore Tamilnadu India

Modified grain refinement influences much enriched properties in Aluminum Metal Matrix composite materials. This paper is analyzed the heat treatment which causes major changes in the eutectic matrix with reinforcement. Wide range of researches are available on the heat treatment of alloy materials, have been reviewed. Even though the microporosity in unavoidable, modified microstructure reveals that spherodization rate of eutectic silicon (Mg2Si) particles are more than ordinary as cast samples. The extent of structural change shows that some parameters like mean diameter, globular shape particles count and secondary dendrite arm spacing are strongly influenced the functional behavior of the material. This research paper investigates the microstructure refinement of Al-Si alloys with various heat treatment holding time.

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An investigation on end milling behaviour of glass fiber reinforced polymer composites

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AIP Conference Proceedings 2024年第1期3178卷

作者： Pratap Shivaji Garudkar Raju Kumar Thakur Santosh Haribhau Pawar Monali Jayram Kshirsagar Vishal Vasant Shinde Kalyan Kumar Singh Department of Automation & Robotics Sandip Institute of Technology & Research Centre Nashik India Brahma Valley College of Engineering & Research Institute Nashik Maharashtra India K. K. Wagh Institute of Engineering Education & Research Nashik Maharashtra India M.V.P.s KBT College of Engineering Nashik Maharashtra India Department of Mechanical Engineering IIT (ISM) Dhanbad India

Glass fibers are frequently utilized as reinforcing polymers. Glass fiber reinforced composites (GFRP) are unique due to their outstanding mechanical and physical characteristics that are useful in industrial applications. In order to mill these composites with good results, minimal fiber delamination and surface quality must be achieved. The current study aimed to improve the two critical milling parameters, feed rate and spindle speed, on performance attributes such as surface roughness (SR) and delamination factor (DF). The experimental design was planned using a Taguchi L9 orthogonal array. ANOVA was utilized to determine the impact of each parameter taken into consideration on performance characteristics. To achieve the lowest DF and SR values, the combination of the ideal parameters was determined to be higher spindle speed (SS) and lower feed rate (FR). Utilizing FESEM, the surface morphology was studied.

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Unraveling the Cr₂N Precipitation and Its Negative Effect on the Corrosion Resistance of Friction Stir Welded UNS S32760 Super Duplex Stainless Steel

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Surfaces and Interfaces 2025年 71卷

作者： Vacchi, G.S. de Carvalho, W.S. Meinhardt, C.P. Bergmann, L.A. Amancio-Filho, S.T. Rovere, C.A.D. Munir Rachid Corrosion Laboratory Department of Materials Engineering Federal University of São Carlos Rodovia Washington Luis Km 235 SP São Carlos 13565-905 Brazil Graduate Program in Materials Science and Engineering Federal University of São Carlos Brazil Institute of Materials Science Joining and Forming BMK Endowed Professorship for Aviation Graz University of Technology – TU Graz Kopernikusgasse 24/1 Graz 8010 Austria Department of Mechanical Engineering Federal University of Pampa Avenida Tiarajú 810 RS Alegrete Brazil Helmholtz-Zentrum Hereon Institute of Materials Mechanics Solid State Materials Processing Max-Planck-Straße 1 Geesthacht Germany

The root surface of a friction stir welded super duplex stainless steel (UNS S32760) was thoroughly characterized in this study. The findings revealed a refined grain structure and a conspicuous increase of 50 HV_0.3 in the Root's hardness. Interestingly, the volume fraction of the ferrite phase remained largely unchanged. Rapid cooling in the welding process led to the Cr₂N precipitation at the ferrite/ferrite grain boundaries in the root area, significantly increasing sensitization, reducing localized corrosion resistance under high electrode potentials in a neutral pH saline environment, and adversely affecting root passivity in a hydrochloric acid environment compared to the base metal. © 2025

关键词： Friction stir welding Localized corrosion Polarization Sensitization Super duplex stainless steel

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Thermal and pH Sensitive Blends Formed by Chitosan and Poly(N-Vinylcaprolactam)

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ChemistrySelect 2025年第23期10卷

作者： Djalma A. Oliveira Maria E. G. Barros Grazielle R. Cerqueira Yêda M. B. Almeida Carolina L. Morelli Materials Science Program Federal University of Pernambuco (UFPE) Recife 50740-600 Brazil Department of Mechanical Engineering Federal University of Pernambuco (UFPE) Recife 50740-600 Brazil Department of Chemical Engineering Federal University of Pernambuco (UFPE) Recife 50740-600 Brazil

The development of smart polymeric films capable of responding to external and internal stimuli is of great interest in the biomedical and industrial fields for applications that require controlled drug release through pH variation, thermal stimuli, or both. This study aimed to develop and characterize polymeric blends composed by chitosan (CS) and poly( N -vinylcaprolactam) (PNVCL) with dual thermal and pH responsiveness. The films were prepared by solution casting using different CS/PNVCL ratios (90/10, 70/30, and 50/50) and characterized by ATR-FTIR, TGA, DSC, SEM, s-SNOM, contact angle, opacification, and swelling tests. FTIR and s-SNOM confirmed interaction and partial miscibility between the polymers. The films exhibited thermoresponsiveness, changing from transparent to opaque in temperatures from 25 °C to 32 °C, depending on composition. The pH responsiveness analysis indicated that the films demonstrated a greater increase in diameter (more than 80%), when subjected to acidic solution. The blend films presented Tg values of 72.38 °C, 140.41 °C, and 142.22 °C for the CS/PNVCL compositions 90/10, 30/70, and 50/50, respectively, intermediate to those observed for the pure precursor polymers (68.74 °C for CS and 182.39 °C for PNVCL). To the best of our knowledge, studies on solid polymeric systems responsive to pH and temperature, like those developed in this work, have not been performed.

关键词： Chitosan CS/PNVCL blends Nano-FTIR Poly(N-vinylcaprolactam) s-SNOM Thermo-pH responsive blends Thermoresponsive blends

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