100 research outputs found
ISIC2018_Task1-2_Training_Input.zip
No full text To comply with the attribution requirements of the CC-BY-NC license , the aggregate "ISIC 2018: Training" data must be cited as:
HAM10000 Dataset: (c) by ViDIR Group, Department of Dermatology, Medical University of Vienna; https://doi.org/10.1038/sdata.2018.161
MSK Dataset: (c) Anonymous; https://arxiv.org/abs/1710.05006; https://arxiv.org/abs/1902.03368
When referencing this dataset in your own manuscripts and publications, please use the following full citations:
[1] Noel Codella, Veronica Rotemberg, Philipp Tschandl, M. Emre Celebi, Stephen Dusza, David Gutman, Brian Helba, Aadi Kalloo, Konstantinos Liopyris, Michael Marchetti, Harald Kittler, Allan Halpern: "Skin Lesion Analysis Toward Melanoma Detection 2018: A Challenge Hosted by the International Skin Imaging Collaboration (ISIC)", 2018; https://arxiv.org/abs/1902.03368
[2] Tschandl, P., Rosendahl, C. & Kittler, H. The HAM10000 dataset, a large collection of multi-source dermatoscopic images of common pigmented skin lesions. Sci. Data 5, 180161 doi:10.1038/sdata.2018.161 (2018).</blockquote
Ultrasonic Investigation of Hepatic Mechanical Properties: Quantifying Tissue Stiffness and Deformation with Increasing Portal Venous Pressure
No full textIn this work, I investigate the mechanical response of the liver to increasing pressure in the portal vein using ultrasonic approaches. In advancing liver disease, portal venous pressure increases lead to severe clinical problems and death. Monitoring these pressure increases can predict patient outcomes and guide treatment. Current methods for measurement of portal venous pressure are invasive, expensive, and therefore are rarely repeated. Ultrasonic methods show promise because they are noninvasive, but traditional ultrasound images and doppler measurements do not yield accurate repeatable measures of hepatic pressure. However, increases in portal venous pressure have been associated with higher estimates of liver stiffness using ultrasound-based shear wave speed estimation algorithms. These quantitative estimates of shear wave speed may provide a mechanism for noninvasive hepatic pressure characterization, but they cannot currently be distinguished from the increases in shear wave speed estimates that are also observed in patients with normal portal venous pressures with advancing liver diseases. Thus, a better understanding of the mechanisms by which hepatic pressure modulates estimates of liver stiffness could provide information needed to distinguish increasing hepatic pressure from advancing brosis stage. This work is devoted to identifying and characterizing the underlying mechanism behind the observed increases in hepatic shear wave speed with pressurization.Two experiments were designed in order to dene the mechanical properties of liver tissue that underlie the observed increase in shear wave speeds with increasing portal venous pressure. First, the behavior of the liver was shown to be nonlinear (or strain-dependent) by comparing stiness estimates in livers that were free to expand and constrained from expansion at increasing hepatic pressures. Shear wave speeds were observed to increase only in the unconstrained case in which the liver was observed to qualitatively deform. Second, the deformation of the liver was quantied using a clinical scanner and 3-D transducer to generate estimates of axial strain during pressurization. Axial strain was found to increase with elevation in portal venous pressure. This axial expansion of the liver also corresponded to increases in shear wave speed estimates with portal venous pressure.The techniques developed herein were used to elucidate mechanical properties of the pressurized liver by concurrent ultrasound-based quantication of hepatic deformation and stiffness. This work shows that increasing shear wave speed estimates with hepatic pressurization are associated with increases in hepatic axial strain measurements. These results provide the basis for quantifying the relationship between pressurization and hepatic strain, laying the foundation for hyperelastic material modeling of the liver. Such nonlinear mechanical models can provide the basis for noninvasive characterization of hepatic pressure using stiffness metrics in the future.</p
The Scope for Exchange Rate Pass-through in an Oligopoly
No full textThis paper represents one of the first analyses of exchange rate pass-through in a dynamic context. It explores the impact of exchange rate fluctuations in a duopoly where firms interact over an indifinite period of time.exchange rate; oligopoly
Agreement Between Experts and an Untrained Crowd for Identifying Dermoscopic Features Using a Gamified App: Reader Feasibility Study
No full textBackground: Dermoscopy is commonly used for the evaluation of pigmented lesions, but agreement between experts for identification of dermoscopic structures is known to be relatively poor. Expert labeling of medical data is a bottleneck in the development of machine learning (ML) tools, and crowdsourcing has been demonstrated as a cost- and time-efficient method for the annotation of medical images. Objective: The aim of this study is to demonstrate that crowdsourcing can be used to label basic dermoscopic structures from images of pigmented lesions with similar reliability to a group of experts. Methods: First, we obtained labels of 248 images of melanocytic lesions with 31 dermoscopic “subfeatures” labeled by 20 dermoscopy experts. These were then collapsed into 6 dermoscopic “superfeatures” based on structural similarity, due to low interrater reliability (IRR): dots, globules, lines, network structures, regression structures, and vessels. These images were then used as the gold standard for the crowd study. The commercial platform DiagnosUs was used to obtain annotations from a nonexpert crowd for the presence or absence of the 6 superfeatures in each of the 248 images. We replicated this methodology with a group of 7 dermatologists to allow direct comparison with the nonexpert crowd. The Cohen κ value was used to measure agreement across raters. Results: In total, we obtained 139,731 ratings of the 6 dermoscopic superfeatures from the crowd. There was relatively lower agreement for the identification of dots and globules (the median κ values were 0.526 and 0.395, respectively), whereas network structures and vessels showed the highest agreement (the median κ values were 0.581 and 0.798, respectively). This pattern was also seen among the expert raters, who had median κ values of 0.483 and 0.517 for dots and globules, respectively, and 0.758 and 0.790 for network structures and vessels. The median κ values between nonexperts and thresholded average–expert readers were 0.709 for dots, 0.719 for globules, 0.714 for lines, 0.838 for network structures, 0.818 for regression structures, and 0.728 for vessels. Conclusions: This study confirmed that IRR for different dermoscopic features varied among a group of experts; a similar pattern was observed in a nonexpert crowd. There was good or excellent agreement for each of the 6 superfeatures between the crowd and the experts, highlighting the similar reliability of the crowd for labeling dermoscopic images. This confirms the feasibility and dependability of using crowdsourcing as a scalable solution to annotate large sets of dermoscopic images, with several potential clinical and educational applications, including the development of novel, explainable ML tools. ©Jonathan Kentley, Jochen Weber, Konstantinos Liopyris, Ralph P Braun, Ashfaq A Marghoob, Elizabeth A Quigley, Kelly Nelson, Kira Prentice, Erik Duhaime, Allan C Halpern, Veronica Rotemberg
A reinforcement learning model for AI-based decision support in skin cancer
No full text: We investigated whether human preferences hold the potential to improve diagnostic artificial intelligence (AI)-based decision support using skin cancer diagnosis as a use case. We utilized nonuniform rewards and penalties based on expert-generated tables, balancing the benefits and harms of various diagnostic errors, which were applied using reinforcement learning. Compared with supervised learning, the reinforcement learning model improved the sensitivity for melanoma from 61.4% to 79.5% (95% confidence interval (CI): 73.5-85.6%) and for basal cell carcinoma from 79.4% to 87.1% (95% CI: 80.3-93.9%). AI overconfidence was also reduced while simultaneously maintaining accuracy. Reinforcement learning increased the rate of correct diagnoses made by dermatologists by 12.0% (95% CI: 8.8-15.1%) and improved the rate of optimal management decisions from 57.4% to 65.3% (95% CI: 61.7-68.9%). We further demonstrated that the reward-adjusted reinforcement learning model and a threshold-based model outperformed naïve supervised learning in various clinical scenarios. Our findings suggest the potential for incorporating human preferences into image-based diagnostic algorithms
Macroeconomic implications of rational expectations for various OECD countries
No full textThe focus of the dissertation is to investigate wage behavior for various OECD countries under the hypothesis of rational expectations. In particular, it focuses on the pattern of instability of wages with implications to model the labor market, combining and institutional approach with an econometric investigation of the data. The body of this dissertation consists of six chapters. Chapter 2 is a review of the literature. It traces the development of the labor market from simple static models to the most complicated dynamic models. Chapter 3 examines the two oil shocks themselves and the aggregate effects on macroeconomic variables in selected OECD countries. Chapter 4 begins with the analysis of the concepts of nominal wage stickiness and real wage stickiness and the establishes the main differences between the two. Additionally, the same chapter develops a model of aggregate supply and demand to explain the important characteristics of the international macroeconomic adjustment in the 1970s. Both models follow the spirit of Branson and Rotemberg (1980) and Sachs (1979) in the assumption of partial wage adjustment to a stochastic target wage. Additionally, extensions and empirical tests of the models are presented. This section investigates whether macroeconomic time series are consistent with time trend decomposition usually employed, and discusses the statistical issues involved in testing for deterministic trends and presents testing unit roots. There is enormous literature on this problem but one of the most commonly used tests is the Dickey-Fuller test. Furthermore, modified log differences transformations were presented and estimated. They show that the U.S. is not the only country in which nominal wages are rigid as pointed out by Branson and Rotemberg. In addition, the chapter looks at the VAR model with impulse response functions and confirms that real wages and nominal wages are not very responsive to changes in unemployment. Finally, cointegration tests between real wages and unemployment as well as nominal wages and unemployment are analyzed. Chapter 5 summarizes the Branson-Rotemberg model and introduces a dynamic version of their model. Chapter 6 concludes the study with the results of the dynamic models with theoretical application or justification and proposes further research. (Abstract shortened with permission of author.
Empirical Models of General Economic Equilibrium
No full textThe article considers possibilities and limitations of empirical models of general economic equilibrium and gives their classification. The author divides computable models of general economic equilibrium into two groups: the first one is based on a model of equilibrium prices (G. Scarf’s approach) and the second one - on a multisectorial model of economic growth (L. Johansen’s approach). The researcher also divides models of dynamic stochastic general equilibrium into two groups: the first one is based on a model of the real business cycle (F. Kydland and E. Prescott’s approach) and the second one - on a model of different behavior of firms under monopolistic competition (J. Rotemberg and M. Woodford’s approach). Within each group the study demarcates empirical models with the help of following criteria: an economy’s scale and its openness; application to current and future assessments; analyzed socio-economic phenomeno
Climate Policy and Border Tax Adjustments: Some New Wine Mixed with Old Wine in New Green Bottles?
No full textCurrent policy discussions are making a very clear connection between domestic climate policies and international trade. In this article, the economic, legal and implementation issues relating to border tax adjustments for climate policies are discussed. The overall conclusion drawn is that the connection between trade and the environment is not new, having been discussed in considerable detail since the early 1990s, and reflected in an extensive economics literature. In addition, the legal aspects of border tax adjustments are not particularly new, although only a WTO ruling on their use in the presence of domestic climate policies will resolve any legal uncertainty about their use. However, there are some new issues concerning the determination and implementation of border tax adjustments for domestic climate polices that do present additional layers of complexity.climate policy, competitiveness, border tax adjustment, Environmental Economics and Policy, Financial Economics, Political Economy,
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