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Fernando Núñez

Publications and source records attributed to Fernando Núñez.

3 recordsLinked to original sources

Data Augmentation with Diffusion Models for Colon Polyp Localization on the Low Data Regime: How much real data is enough?

The scarcity of data in medical domains hinders the performance of Deep Learning models. Data augmentation techniques can alleviate that problem, but they usually rely on functional transformations of the data that do not guarantee to preserve the original tasks. To approximate the distribution of the data using generative models is a way of reducing that problem and also to obtain new samples that resemble the original data. Denoising Diffusion models is a promising Deep Learning technique that can learn good approximations of different kinds of data like images, time series or tabular data. Automatic colonoscopy analysis and specifically Polyp localization in colonoscopy videos is a task that can assist clinical diagnosis and treatment. The annotation of video frames for training a deep learning model is a time consuming task and usually only small datasets can be obtained. The fine tuning of application models using a large dataset of generated data could be an alternative to improve their performance. We conduct a set of experiments training different diffusion models that can generate jointly colonoscopy images with localization annotations using a combination of existing open datasets. The generated data is used on various transfer learning experiments in the task of polyp localization with a model based on YOLO v9 on the low data regime.

cs.CV↗

The Iberian Exception: An overview of its effects over its first 100 days

This paper offers an independent assessment of certain key economic effects of the Iberian Exception (IE). Their stated aim was to reduce the major component of electricity prices for most Iberian consumers, a component which was indexed to Iberian wholesale power market spot prices power market prices that were rising alarmingly due to extremely tight international markets for natural gas. The Spanish Government estimates that, during its first 100 days, the IE provided substantial benefits for consumers affected by the IE, which included over 10 million small consumers as well as many large ones, but the authors of this study question that estimate. The authors of this paper argue that the estimated effect of the IE on retail prices depends critically on the assumptions about what would have occurred in the absence of the IE, i.e., in a counterfactual scenario. Although counterfactuals are always difficult to construct, the government s counterfactual ignores demand elasticity, and this inflates their estimate of immediate consumer benefits. Using hourly data on the wholesale electricity market for the first 100 days of the IE, this paper s analysis of alternative counterfactuals that reflect the effects of demand elasticity shows substantially lower benefits of the IE for consumers than the Spanish government estimates. Indeed, this paper s analysis suggests that affected consumers would have paid somewhat less for electricity in the first 100 days of the IE had it not been introduced. The authors identify several other potential short and longterm effects of the IE that deserve further study. These include increased margins for fossil fired generators, reduced margins for some decarbonized inframarginal plant, heightened investor perceptions of regulatory risk, weakened incentives for efficient consumption, and higher carbon emissions and gas prices.

econ.GN↗

An assessment of European electricity arbitrage using storage systems

This study analyses the current viability of this business based on a sample of European countries in the year 2019; countries where electricity prices (day-ahead market) and financial conditions show a certain degree of heterogeneity. We basically follow a sequence of three analyses in our study. Firstly, a Linear Mixed-Integrated Programming model has been developed to optimize the arbitrage strategy for each country in the sample. Secondly, using the cash-flows from the optimization model, we calculate two financial indicators (NPV and IRR) in order to select the optimal converter size for each country. Tax and discount rates specific to each country have been used with the calculation of this second rate following the methodology proposed by the Spanish regulator. Thirdly, a mixed linear regression model is proposed in order to investigate the importance of observed and unobserved heterogeneity (at country level) in explaining the business profitability.

econ.GN↗