A new Database of Parliamentary Debates in Ireland, 1922--2008

We present a new database of parliamentary debates and written answers in Dáil Éireann for the entire time period from the third Dáil in 1922 to the thirtieth Dáil in 2008. This database was built from the Official Records of the Houses of the Oireachtas. Unlike its original version, our database integrates information about debates and information about deputies into a single database. This database therefore allows to search and retrieve contributions from individual deputies of the Dáil (Teachta Dála or TD) and to combine information about TDs' parties and constituencies with the history of political speeches and written answers. In addition, our database facilitates the application of content analysis software such as Wordscore (Laver, Benoit and Garry, 2003) or Wordfish (Slapin and Proksch, 2008) and makes it possible to estimate TDs' policy preferences from speeches. In this paper we document the structure of the database and how it was generated. We furthermore demonstrate how political debates can be used in social science research through a series of examples. These include an analysis of the policy agenda in all budget speeches from 1922 to today, the estimation of speakers' policy positions in the 2008 budget debate, and the estimation of ministers' policy positions in the 26th government in 2002.parliamentary debates, policy point estimation, budget speeches, text analysis

Estimating Government Discretion in Fiscal Policy Making

Varieties of Capitalism (VoC) is a relatively new approach to describe macroeconomic differences across countries, classifying them into coordinated market economies (CMEs) and liberal market economies (LMEs). VoC already had a significant impact on the field but has been criticised for its lack of linkage to political systems. Recent studies focused on the similarities between CMEs and the Lijphartian consensus political systems, and LMEs and majoritarian political systems. One of the practical consequences of this classification is that governments in LMEs should enjoy more discretion over fiscal policy while governments in CMEs are more constrained in their decisions. In this paper we evaluate this proposition in two LME states -- Ireland and the UK -- where the latter is an example of a pure majoritarian state while the former bares several institutional characteristics of the consensus state (e.g. electoral system and coalition governments). We show that governments in both states enjoy relatively high degrees of discretion over fiscal policy, but that in Ireland policy outcomes are more well balanced in respect to interests represented by social partners. We thus provide empirical evidence that supports the classification proposed in the VoC approach. However, we also demonstrate that the context of decision-making has a crucial impact on the discretionary power of government, and that such context effects can change over time, even within the same system type.fiscal policy, computerised text analysis, EU Structural Funds, budgetary process

Games of Status and Discrininatory Contract

Following recent empirical evidence which indicates the importance of rank for the determination of workers’ wellbeing, this paper introduces status seeking preferences in the form of rank-dependent utility functions into a moral hazard framework with one firm and multiple workers, but no correlation in production. Workers’ concern for the rank of their wage in the firm’s wage distribution may induce the firm to offer discriminatory wage contracts when its aim is to induce all workers to expend effort.

Transfer Topic Labeling with Domain-Specific Knowledge Base: An Analysis of UK House of Commons Speeches 1935-2014

Topic models are widely used in natural language processing, allowing researchers to estimate the underlying themes in a collection of documents. Most topic models use unsupervised methods and hence require the additional step of attaching meaningful labels to estimated topics. This process of manual labeling is not scalable and suffers from human bias. We present a semi-automatic transfer topic labeling method that seeks to remedy these problems. Domain-specific codebooks form the knowledge-base for automated topic labeling. We demonstrate our approach with a dynamic topic model analysis of the complete corpus of UK House of Commons speeches 1935-2014, using the coding instructions of the Comparative Agendas Project to label topics. We show that our method works well for a majority of the topics we estimate; but we also find that institution-specific topics, in particular on subnational governance, require manual input. We validate our results using human expert coding

Learning a Structured Neural Network Policy for a Hopping Task

In this work we present a method for learning a reactive policy for a simple dynamic locomotion task involving hard impact and switching contacts where we assume the contact location and contact timing to be unknown. To learn such a policy, we use optimal control to optimize a local controller for a fixed environment and contacts. We learn the contact-rich dynamics for our underactuated systems along these trajectories in a sample efficient manner. We use the optimized policies to learn the reactive policy in form of a neural network. Using a new neural network architecture, we are able to preserve more information from the local policy and make its output interpretable in the sense that its output in terms of desired trajectories, feedforward commands and gains can be interpreted. Extensive simulations demonstrate the robustness of the approach to changing environments, outperforming a model-free gradient policy based methods on the same tasks in simulation. Finally, we show that the learned policy can be robustly transferred on a real robot.Comment: IEEE Robotics and Automation Letters 201

Trajectory generation for multi-contact momentum-control

Simplified models of the dynamics such as the linear inverted pendulum model (LIPM) have proven to perform well for biped walking on flat ground. However, for more complex tasks the assumptions of these models can become limiting. For example, the LIPM does not allow for the control of contact forces independently, is limited to co-planar contacts and assumes that the angular momentum is zero. In this paper, we propose to use the full momentum equations of a humanoid robot in a trajectory optimization framework to plan its center of mass, linear and angular momentum trajectories. The model also allows for planning desired contact forces for each end-effector in arbitrary contact locations. We extend our previous results on LQR design for momentum control by computing the (linearized) optimal momentum feedback law in a receding horizon fashion. The resulting desired momentum and the associated feedback law are then used in a hierarchical whole body control approach. Simulation experiments show that the approach is computationally fast and is able to generate plans for locomotion on complex terrains while demonstrating good tracking performance for the full humanoid control

Humanoid Momentum Estimation Using Sensed Contact Wrenches

This work presents approaches for the estimation of quantities important for the control of the momentum of a humanoid robot. In contrast to previous approaches which use simplified models such as the Linear Inverted Pendulum Model, we present estimators based on the momentum dynamics of the robot. By using this simple yet dynamically-consistent model, we avoid the issues of using simplified models for estimation. We develop an estimator for the center of mass and full momentum which can be reformulated to estimate center of mass offsets as well as external wrenches applied to the robot. The observability of these estimators is investigated and their performance is evaluated in comparison to previous approaches.Comment: Submitted to the 15th IEEE RAS Humanoids Conference, to be held in Seoul, Korea on November 3 - 5, 201

Exploring the properties of titin spring elements in whole myofibrils

INTRODUCTIONTitin is the largest protein in animals and is primarily found in the sarcomeres of myofibrils. Titin acts as a spring anchored by actin at the z-line and holding myosin filaments centred in sarcomeres. Titin has long been accepted as a major contributor to passive force in myofibrils. The most ground-breaking work on titin was done by Kellermayer et al. who found that at short and long lengths titin behaved elastically while at intermediate lengths it behaved visco-elastically which they attributed to the unfolding of Immunoglobulin (Ig) domains (1).While many studies have examined the passive stretching of whole myofibrils, there is little examining titin’s properties within its natural environment, the sarcomere. Because titin contributes up to 95% of the passive force in myofibrils, its  properties are reflected in whole myofibrils (2). The purpose of this study was to test the idea that titin is elastic at long length when Ig domain unfolding and refolding is prevented.METHODSMuscle tissue was collected from rabbit psoas. Connective tissues were digested and myofibrils were mechanically separated. Isolated myofibrils were then attached to a rigid glass needle at one end to control lengths, while the other end of the myofibril was attached to a silicon nitrate lever with a stiffness of 68nN/um to measure the force.Myofibrils were set at a length of 2.7um/sarcomere and then stretched at 0.1um/(sarcomere x seconds) to 4.7um/sarcomere. The myofibrils were then held at that length for 120 seconds to allow Ig domain unfolding to reach a steady state. The myofibril was the stretched and relaxed in 10 cycles of 0.5um/sarcomere at a speed of 0.1um/(sarcomere x seconds). A total of 9 myofibrils were tested and analyzed.RESULTSAll nine myofibrils showed the same consistent behaviour (Figure 1). During the initial stretch force rose as length increased, and then gradually decreased during the 120 second stress relaxation. During the ten stretch-relaxation cycles a visco-elastic behaviour was observed as each cycle showed a small but distinct hysteresis. The force during stretch was always greater than the force during shortening, and forces were at a near steady-state for all ten cycles. It should also be noted that the force during the first relaxation cycle was much lower at the same length as the relaxation of all of the subsequent cycles. Figure 1. Graph typical of the tests, with force graphed versus length. A) initial stretch. B) the stress relaxation as force decreases and length increases over 120 seconds. C)  shows the cycles of stretch relaxation in that order.DISCUSSION AND CONCLUSIONSThe results that we observed contradict our initial hypothesis as the elastic behaviour described by Kellermayer was not observed. This could be due to some unforeseen myofibrilar protein that contributes to the stiffness of the myofibril, however due to the long length, high force and quick period of recovery of stiffness seen in the myofibril other sarcomeric protiens are likely not responsible. We can also rule out refolding of Ig domains as work done by Kellermayer and our lab in the past corroborates their finding that this occurs slowly at shorter sarcomere lengths with little to no passive force. The work done by Kellermayer is very sound however and cannot just be dismissed. Therefore we are led to believe that this visco-elastic behaviour observed at long lengths in myofibrils is due to titin properties that present themselves in whole myofibrils. This may be caused by quick interactions between titin and other myofibrilar proteins that leads to a increase in stiffness at long lengths and high forces.REFERENCES1.    M. S. Z. Kellermayer, S. B. Smith, H. L. M. Granzier, C. Bustamante, Science 276, 1112 (1997).2.    J. A. Herzog, T. R. Leonard, A. Jinha, W. Herzog, J. Biomech. 45, 1893 (2012)

Balancing experiments on a torque-controlled humanoid with hierarchical inverse dynamics

Recently several hierarchical inverse dynamics controllers based on cascades of quadratic programs have been proposed for application on torque controlled robots. They have important theoretical benefits but have never been implemented on a torque controlled robot where model inaccuracies and real-time computation requirements can be problematic. In this contribution we present an experimental evaluation of these algorithms in the context of balance control for a humanoid robot. The presented experiments demonstrate the applicability of the approach under real robot conditions (i.e. model uncertainty, estimation errors, etc). We propose a simplification of the optimization problem that allows us to decrease computation time enough to implement it in a fast torque control loop. We implement a momentum-based balance controller which shows robust performance in face of unknown disturbances, even when the robot is standing on only one foot. In a second experiment, a tracking task is evaluated to demonstrate the performance of the controller with more complicated hierarchies. Our results show that hierarchical inverse dynamics controllers can be used for feedback control of humanoid robots and that momentum-based balance control can be efficiently implemented on a real robot.Comment: appears in IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 201

Pattern Generation for Walking on Slippery Terrains

In this paper, we extend state of the art Model Predictive Control (MPC) approaches to generate safe bipedal walking on slippery surfaces. In this setting, we formulate walking as a trade off between realizing a desired walking velocity and preserving robust foot-ground contact. Exploiting this formulation inside MPC, we show that safe walking on various flat terrains can be achieved by compromising three main attributes, i. e. walking velocity tracking, the Zero Moment Point (ZMP) modulation, and the Required Coefficient of Friction (RCoF) regulation. Simulation results show that increasing the walking velocity increases the possibility of slippage, while reducing the slippage possibility conflicts with reducing the tip-over possibility of the contact and vice versa.Comment: 6 pages, 7 figure