3D Masked Autoencoders with Application to Anomaly Detection in Non-Contrast Enhanced Breast MRI

Self-supervised models allow (pre-)training on unlabeled data and therefore have the potential to overcome the need for large annotated cohorts. One leading self-supervised model is the masked autoencoder (MAE) which was developed on natural imaging data. The MAE is masking out a high fraction of visual transformer (ViT) input patches, to then recover the uncorrupted images as a pretraining task. In this work, we extend MAE to perform anomaly detection on breast magnetic resonance imaging (MRI). This new model, coined masked autoencoder for medical imaging (MAEMI) is trained on two non-contrast enhanced MRI sequences, aiming at lesion detection without the need for intravenous injection of contrast media and temporal image acquisition. During training, only non-cancerous images are presented to the model, with the purpose of localizing anomalous tumor regions during test time. We use a public dataset for model development. Performance of the architecture is evaluated in reference to subtraction images created from dynamic contrast enhanced (DCE)-MRI

Influence of Substrate Temperature on Structural and Morphological Properties of SnO2 Nanostructured Thin Films

SnO2 nanostructures thin films with thickness of 500 nm were prepared by electron beam-physical vapor deposition on glass substrate at temperature of 300, 373, 443, and 583 K. Structural and morphological properties of these nanostructured thin films were studied by Scanning and Transmission Electron Microscopy (SEM, TEM) and Atomic Force Microscope (AFM) methods. The changes in structural and morphological properties are found at different temperatures. Increase temperature causes important change of the structural and morphological properties. The sample prepared at 300 K has crystalline structure and the sample prepared at 583 K has amorphous structure. Roughness parameters have low values at 300, 373, 443 K as opposed to the values obtained at 583 K. This different behavior may be due to the amorphous structure of the sample that was observed in the TEM analysis

Equilibrium swelling and universal ratios in dilute polymer solutions: Exact Brownian dynamics simulations for a delta function excluded volume potential

A narrow Gaussian excluded volume potential, which tends to a delta-function repulsive potential in the limit of a width parameter d* going to zero, has been used to examine the universal consequences of excluded volume interactions on the equilibrium and linear viscoelastic properties of dilute polymer solutions. Brownian dynamics simulations data, acquired for chains of finite length, has been extrapolated to the limit of infinite chain length to obtain model independent predictions. The success of the method in predicting well known aspects of static solution properties suggests that it can be used as a systematic means by which the influence of solvent quality on both equilibrium and non-equilibrium properties can be studied.Comment: Revised version submitted to Physical Review Letters. 4 pages, 2 figures (revised with additional data

Technology Transfers and the Clean Development Mechanism in a North-South General Equilibrium Model

This paper analyzes the potential welfare gains of introducing a technology transfer from Annex I to non-Annex I in order to mitigate greenhouse gas emissions. Our analysis is based on a numerical general equilibrium model for a world economy comprising two regions, North (Annex I) and South (non-Annex I). As our model allows for labor mobility between the formal and informal sectors in the South, we are also able to capture additional aspects of how the transfer influences the Southern economy. In a cooperative equilibrium, a technology transfer from the North to the South is clearly desirable from the perspective of a global social planner, since the welfare gain for the South outweighs the welfare loss for the North. However, if the regions do not cooperate, then the incentives to introduce the technology transfer appear to be relatively weak from the perspective of the North; at least if we allow for Southern abatement in the pre-transfer Nash equilibrium. Finally, by adding the emission reductions associated with the Kyoto agreement to an otherwise uncontrolled market economy, the technology transfer leads to higher welfare in both regions

Cost Effectiveness in River Management: Evaluation of Integrated River Policy System in Tidal Ouse

The River Ouse forms a significant part of Humber river system, which drains about one fifth the land area of England and provides the largest fresh water source to the North Sea from UK. The river quality in the tidal river suffered from sag of dissolved oxygen (DO) during last few decades, deteriorated by the effluent discharges. The Environment Agency (EA) proposed to increase the water quality of Ouse by implementing more potent environmental policies. This paper explores the cost effectiveness of water management in the Tidal Ouse through various options by taking into account the variation of assimilative capacity of river water, both in static and dynamic scope of time. Reduction in both effluent discharges and water abstraction were considered along side with choice of effluent discharge location. Different instruments of environmental policy, the emission tax-subsidy (ETS) scheme and tradable pollution permits (TPP) systems were compared with the direct quantitative control approach. This paper at the last illustrated an empirical example to reach a particular water quality target in the tidal Ouse at the least cost, through a solution of constrained optimisation problem. The results suggested significant improvement in the water quality with less cost than current that will fail the target in low flow year

Marginal Cost versus Average Cost Pricing with Climatic Shocks in Senegal: A Dynamic Computable General Equilibrium Model Applied to Water

The model simulates on a 20-year horizon, a first phase of increase in the water resource availability taking into account the supply policies by the Senegalese government and a second phase with hydrologic deficits due to demand evolution (demographic growth). The results show that marginal cost water pricing (with a subsidy ensuring the survival of the water production sector) makes it possible in the long term to absorb the shock of the resource shortage, GDP, investment and welfare increase. Unemployment drops and the sectors of rain rice, market gardening and drinking water distribution grow. In contrast, the current policy of average cost pricing of water leads the long-term economy in a recession with an agricultural production decrease, a strong degradation of welfare and a rise of unemployment. This result questions the basic tariff (average cost) on which block water pricing is based in Senegal

The Role of Risk Aversion and Lay Risk in the Probabilistic Externality Assessment for Oil Tanker Routes to Europe

Oil spills are a major cause of environmental concern, in particular for Europe. However, the traditional approach to the evaluation of the expected external costs of these accidents fails to take into full account the implications of their probabilistic nature. By adapting a methodology originally developed for nuclear accidents to the case of oil spills, we extend the traditional approach to the assessment of the welfare losses borne by potentially affected individuals for being exposed to the risk of an oil spill. The proposed methodology differs from the traditional approach in three respects: it allows for risk aversion; it adopts an ex-ante rather than an ex-post perspective; it allows for subjective oil spill probabilities (held by the lay public) higher than those assessed by the experts in the field. In order to illustrate quantitatively this methodology, we apply it to the hypothetical (yet realistic) case of an oil spill in the Aegean Sea. We assess the risk premiums that potentially affected individuals would be willing to pay in order to avoid losses to economic activities such as tourism and fisheries, and non-use damages resulting from environmental impacts on the Aegean coasts. In the scenarios analysed, the risk premiums on expected losses for tourism and fisheries turn out to be substantial when measured as a percentage of expected losses; by contrast, they are quite small for the case of damages to the natural environment

Recent experimental probes of shear banding

Recent experimental techniques used to investigate shear banding are reviewed. After recalling the rheological signature of shear-banded flows, we summarize the various tools for measuring locally the microstructure and the velocity field under shear. Local velocity measurements using dynamic light scattering and ultrasound are emphasized. A few results are extracted from current works to illustrate open questions and directions for future research.Comment: Review paper, 23 pages, 11 figures, 204 reference

Quality of Available Mates, Education and Intra-Household Bargaining Power

This paper further explores the role of sex ratios on spouses bargaining power, by focusing on educational attainment in order to capture the qualitative aspect of mate availability. Using Census and Current Population Survey data for U.S. metropolitan areas in year 2000, a quality sex ratio is constructed by education brackets to test the effect on the intra-household bargaining power of couples in the corresponding education bracket. We argue that a relative shortage of suitably educated women in the spouses potential marriage market increases wives bargaining power in the household while it lowers their husbands. Additionally, we test the prediction that this bargaining power effect is greater as the assortative mating order by education increases. We consider a collective labor supply household model, in which each spouses labor supply is negatively related to their level of bargaining power. We find that higher relative shortage of comparably educated women in the couples metropolitan area reduces wives labor supply and increases their husbands. Also, the labor supply impact is stronger for couples in higher education groups. No such effects are found for unmarried individuals, which is consistent with bargaining theory