Do reductions of standard hours affect employment transitions? : Evidence from Chile

This study exploits the reduction of weekly working hours from 48 to 45 occured in Chile in January 2005. We use this pure and exogenous policy change to identify the employment effects of such a policy. Our main contribution is that we overcome the problems of previous studies such as : selection between hours and employment, lack of identification strategy due to the joint implementation of policies and lack of crucial variables (like hourly wages and usual hours). Our results suggest no significant effects of a reduction of standard hours on employment transitions and a significant effect on hourly wages (i.e. wage compensation). These results are robust to several specifiations.

Mesoscopic Coulomb drag, broken detailed balance and fluctuation relations

When a biased conductor is put in proximity with an unbiased conductor a drag current can be induced in the absence of detailed balance. This is known as the Coulomb drag effect. However, even in this situation far away from equilibrium where detailed balance is explicitly broken, theory predicts that fluctuation relations are satisfied. This surprising effect has, to date, not been confirmed experimentally. Here we propose a system consisting of a capacitively coupled double quantum dot where the nonlinear fluctuation relations are verified in the absence of detailed balance.Comment: 4 pages, 3 figure

Dark Bell states in tunnel-coupled spin qubits

We investigate the dynamical purification of maximally entangled electron states by transport through coupled quantum dots. Under resonant ac driving and coherent tunneling, even-parity Bell states perform Rabi oscillations that decouple from the environment, leading to a dark state. The two electrons remain spatially separated, one in each quantum dot. We propose configurations where this effect will prove as antiresonances in transport spectroscopy experiments.Comment: 5 pages, 4 figures + supplementary information. Published versio

Detection of single-electron heat transfer statistics

We consider a quantum dot system whose charge fluctuations are monitored by a quantum point contact allowing for the detection of both charge and transferred heat statistics. Our system consists of two nearby conductors that exchange energy via Coulomb interaction. In interfaces consisting of capacitively coupled quantum dots, energy transfer is discrete and can be measured by charge counting statistics. We investigate gate dependent deviations away from a charge fluctuation theorem in the presence of local temperature gradients (hot spots). Non universal relations are found for state dependent charge counting. A fluctuation theorem holds for coupled dot configurations with heat exchange and no net particle flow.Comment: 6 pages, 3 figures. Published version. Corrected after erratum publicatio

Light-induced effects on Spiro-OMeTAD films and hybrid lead halide perovskite solar cells

Perovskite (PS) solar cells have emerged as a promising technology for low-cost and efficient photovoltaics. However, the main limiting factors are related to their low long-term stability. The loss of performance of these devices is commonly attributed to degradation of the PS itself. In order to further explore the origins of such limited stability, we have developed UV–vis spectroscopy studies that clearly demonstrate that PS layers remain unalterable under the working conditions. On the contrary, significant variations in the absorption spectra of the Spiro-OMeTAD layer (Spiro), a commonly used hole transporting material (HTM), indicate that the loss of performance over the irradiation time are attributed to the degradation of Spiro. UV–vis measurements evidence a photo-induced oxidation of Spiro, both under air and inert atmosphere. This photo-oxidation is accelerated by the commonly employed additives of the Spiro (LiTFSI and tBP), as well as by the interfacial contact with the electron injecting layer (TiO2). Therefore, our results point to the Spiro degradation as the main mechanism that induces the limited functioning of the PS solar cells. Consequently, focusing on the development of alternative HTMs stable under the working conditions is one of the critical issues to be overcome for a suitable progress of PS solar cells and related opto-electronic devices

MIMO PID Controller Tuning Method for Quadrotor Based on LQR/LQG Theory

In this work, a new pre-tuning multivariable PID (Proportional Integral Derivative) controllers method for quadrotors is put forward. A procedure based on LQR/LQG (Linear Quadratic Regulator/Gaussian) theory is proposed for attitude and altitude control, which suposes a considerable simplification of the design problem due to only one pretuning parameter being used. With the aim to analyze the performance and robustness of the proposed method, a non-linear mathematical model of the DJI-F450 quadrotor is employed, where rotors dynamics, together with sensors drift/bias properties and noise characteristics of low-cost commercial sensors typically used in this type of applications are considered. In order to estimate the state vector and compensate bias/drift effects in the measures, a combination of filtering and data fusion algorithms (Kalman filter and Madgwick algorithm for attitude estimation) are proposed and implemented. Performance and robustness analysis of the control system is carried out by employing numerical simulations, which take into account the presence of uncertainty in the plant model and external disturbances. The obtained results show the proposed controller design method for multivariable PID controller is robust with respect to: (a) parametric uncertainty in the plant model, (b) disturbances acting at the plant input, (c) sensors measurement and estimation errors

Dynamical Coulomb blockade of thermal transport

The role of energy exchange between a quantum system and its environment is investigated from the perspective of the Onsager conductance matrix. We consider the thermoelectric linear transport of an interacting quantum dot coupled to two terminals under the influence of an electrical potential and a thermal bias. We implement in our model the effect of coupling to electromagnetic environmental modes created by nearby electrons within the P(E)-theory of dynamical Coulomb blockade. Our findings relate the lack of some symmetries among the Onsager matrix coefficients with an enhancement of the efficiency at maximum power and the occurrence of the heat rectification phenomenon.Comment: 9 pages, 7 figure