Learning an Interactive Segmentation System

Many successful applications of computer vision to image or video manipulation are interactive by nature. However, parameters of such systems are often trained neglecting the user. Traditionally, interactive systems have been treated in the same manner as their fully automatic counterparts. Their performance is evaluated by computing the accuracy of their solutions under some fixed set of user interactions. This paper proposes a new evaluation and learning method which brings the user in the loop. It is based on the use of an active robot user - a simulated model of a human user. We show how this approach can be used to evaluate and learn parameters of state-of-the-art interactive segmentation systems. We also show how simulated user models can be integrated into the popular max-margin method for parameter learning and propose an algorithm to solve the resulting optimisation problem.Comment: 11 pages, 7 figures, 4 table

Learning Less is More - 6D Camera Localization via 3D Surface Regression

Popular research areas like autonomous driving and augmented reality have renewed the interest in image-based camera localization. In this work, we address the task of predicting the 6D camera pose from a single RGB image in a given 3D environment. With the advent of neural networks, previous works have either learned the entire camera localization process, or multiple components of a camera localization pipeline. Our key contribution is to demonstrate and explain that learning a single component of this pipeline is sufficient. This component is a fully convolutional neural network for densely regressing so-called scene coordinates, defining the correspondence between the input image and the 3D scene space. The neural network is prepended to a new end-to-end trainable pipeline. Our system is efficient, highly accurate, robust in training, and exhibits outstanding generalization capabilities. It exceeds state-of-the-art consistently on indoor and outdoor datasets. Interestingly, our approach surpasses existing techniques even without utilizing a 3D model of the scene during training, since the network is able to discover 3D scene geometry automatically, solely from single-view constraints.Comment: CVPR 201

Fiscal policy and inflation volatility

Among the harmful effects of inflation, the negative consequences of inflation volatility are of particular concern. These include higher risk premia, hedging costs and unforeseen redistribution of wealth. This paper presents panel estimations for a sample of OECD countries which suggest that activist fiscal policies may have an important impact on CPI inflation volatility. Major results are robust for unconditional and conditional inflation volatility, the latter derived from country-specific GARCH models, and across different data frequencies, time periods and econometric methodologies. From a policy perspective, these results point to the possibility of further destabilising effects of discretionary fiscal policies, in addition to their potential to destabilise output. JEL Classification: E31, E62Fiscal Policy, inflation volatility

The impact of high and growing government debt on economic growth: an empirical investigation for the euro area

This paper investigates the average impact of government debt on per-capita GDP growth in twelve euro area countries over a period of about 40 years starting in 1970. It finds a non-linear impact of debt on growth with a turning point—beyond which the government debt-to-GDP ratio has a deleterious impact on long-term growth—at about 90-100% of GDP. Confidence intervals for the debt turning point suggest that the negative growth effect of high debt may start already from levels of around 70-80% of GDP, which calls for even more prudent indebtedness policies. At the same time, there is evidence that the annual change of the public debt ratio and the budget deficit-to-GDP ratio are negatively and linearly associated with per-capita GDP growth. The channels through which government debt (level or change) is found to have an impact on the economic growth rate are: (i) private saving; (ii) public investment; (iii) total factor productivity (TFP) and (iv) sovereign long-term nominal and real interest rates. From a policy perspective, the results provide additional arguments for debt reduction to support longer-term economic growth prospects. JEL Classification: H63, O40, E62, E43Economic Growth, Fiscal Policy, public debt, sovereign long-term interest rates

Major public debt reductions: Lessons from the past, lessons for the future

The financial crisis of 2008/2009 has left European economies with a sizeable public debt stock bringing back the question what factors help to reduce these fiscal imbalances. Using data for the period 1985-2009 this paper identifies factors determining major public debt reductions. On average, the total debt reduction per country amounted to almost 37 percentage points of GDP. We estimate several specifications of a logistic probability model. Our findings suggest that, first, major debt reductions are mainly driven by decisive and lasting (rather than timid and short-lived) fiscal consolidation efforts focused on reducing government expenditure, in particular, cuts in social benefits and public wages. Second, robust real GDP growth also increases the likelihood of a major debt reduction because it helps countries to "grow their way out" of indebtedness. Third, high debt servicing costs play a disciplinary role strengthened by market forces and require governments to set up credible plans to stop and reverse the increasing debt ratios. JEL Classification: C35, E62, H6binary choice models, Fiscal Policy, public debt

Selenocysteine, pyrrolysine and the unique energy metabolism of methanogenic archaea

Methanogenic archaea are a group of strictly anaerobic microorganisms characterized by their strict dependence on the process of methanogenesis for energy conservation. Among the archaea, they are also the only known group synthesizing proteins containing selenocysteine or pyrrolysine. All but one of the known archaeal pyrrolysine-containing and all but two of the confirmed archaeal selenocysteine-containing protein are involved in methanogenesis. Synthesis of these proteins proceeds through suppression of translational stop codons but otherwise the two systems are fundamentally different. This paper highlights these differences and summarizes the recent developments in selenocysteine- and pyrrolysine-related research on archaea and aims to put this knowledge into the context of their unique energy metabolism

What “Hides” Behind Sovereign Debt Ratings?

In this paper we study the determinants of sovereign debt credit ratings using rating notations from the three main international rating agencies, for the period 1995-2005. We employ panel estimation and random effects ordered probit approaches to assess the explanatory power of several macroeconomic and public governance variables. Our results point to a good performance of the estimated models, across agencies and across the time dimension, as well as a good overall prediction power. Relevant explanatory variables for a country's credit rating are: GDP per capita, GDP growth, government debt, government effectiveness indicators, external debt, external reserves, and default history.credit ratings; sovereign debt; rating agencies; panel data; random effects ordered probit.

The impact of numerical expenditure rules on budgetary discipline over the cycle

We study the impact of numerical expenditure rules on the propensity of governments to deviate from expenditure targets in response to surprises in cyclical conditions. Theoretical considerations suggest that due to political fragmentation in the budgetary process expenditure policy might be prone to a pro-cyclical bias. However, this tendency may be mitigated by numerical expenditure rules. These hypotheses are tested against data from a panel of EU Member States. Our key findings are that (i) deviations between actual and planned government expenditure are positively related to unanticipated changes in the output gap, and (ii) numerical expenditure rules reduce this pro-cyclical bias. Moreover, the pro-cyclical spending bias is found to be particularly pronounced for spending items with a high degree of budgetary flexibility. JEL Classification: C23, E62, H50expenditure rules, fiscal discipline, spending bias, stabilisation