What Explains Fertility? Evidence from Italian Pension Reforms

Why do people have kids in developed societies? We propose an empirical test of two alternative theories — children as “consumption” vs. “investment” good. We use as a natural experiment the Italian pension reforms of the 90s that introduced a clear discontinuity in the treatment across workers. This policy experiment is particularly well suited, since the “consumption” motive predicts lower future pensions to reduce fertility, while the “old-age security” to increase it. Our empirical analysis identifies a clear and robust positive effect of less generous future pensions on post-reform fertility. These findings are consistent with “old-age security” even for contemporary fertility.old-age security, public pension systems, fertility, altruism

Transformer Networks for Trajectory Forecasting

Most recent successes on forecasting the people motion are based on LSTM models and all most recent progress has been achieved by modelling the social interaction among people and the people interaction with the scene. We question the use of the LSTM models and propose the novel use of Transformer Networks for trajectory forecasting. This is a fundamental switch from the sequential step-by-step processing of LSTMs to the only-attention-based memory mechanisms of Transformers. In particular, we consider both the original Transformer Network (TF) and the larger Bidirectional Transformer (BERT), state-of-the-art on all natural language processing tasks. Our proposed Transformers predict the trajectories of the individual people in the scene. These are "simple" model because each person is modelled separately without any complex human-human nor scene interaction terms. In particular, the TF model without bells and whistles yields the best score on the largest and most challenging trajectory forecasting benchmark of TrajNet. Additionally, its extension which predicts multiple plausible future trajectories performs on par with more engineered techniques on the 5 datasets of ETH + UCY. Finally, we show that Transformers may deal with missing observations, as it may be the case with real sensor data. Code is available at https://github.com/FGiuliari/Trajectory-Transformer.Comment: 18 pages, 3 figure

MX-LSTM: mixing tracklets and vislets to jointly forecast trajectories and head poses

Recent approaches on trajectory forecasting use tracklets to predict the future positions of pedestrians exploiting Long Short Term Memory (LSTM) architectures. This paper shows that adding vislets, that is, short sequences of head pose estimations, allows to increase significantly the trajectory forecasting performance. We then propose to use vislets in a novel framework called MX-LSTM, capturing the interplay between tracklets and vislets thanks to a joint unconstrained optimization of full covariance matrices during the LSTM backpropagation. At the same time, MX-LSTM predicts the future head poses, increasing the standard capabilities of the long-term trajectory forecasting approaches. With standard head pose estimators and an attentional-based social pooling, MX-LSTM scores the new trajectory forecasting state-of-the-art in all the considered datasets (Zara01, Zara02, UCY, and TownCentre) with a dramatic margin when the pedestrians slow down, a case where most of the forecasting approaches struggle to provide an accurate solution.Comment: 10 pages, 3 figures to appear in CVPR 201

Modellizzazione di polaroni in DFT: TiO2 Rutilo

Lo scopo di questa tesi è quello di introdurre alcuni concetti base di Density Functional Theory (DFT) e presentare, attraverso una breve trattazione teorica e una simulazione in VASP, il problema dei polaroni. Nel primo capitolo si delineano i punti fondamentali dei metodi di DFT (DFT standard e DFT+U), mentre nel secondo capitolo viene descritta la formazione di polaroni secondo le formulazioni di Frölich e Holstein, presentando quindi le differenze tra i due approcci. Nei successivi capitoli si descrive la simulazione di un polarone di Holstein in un cristallo di Rutilo (TiO2), un ossido di un metallo di transizione. Inizialmente vengono elencati i metodi computazionali usati per trattare la DFT in modellizzazioni di questo tipo e si presenta VASP (Vienna Ab-initio Simulation Package), il software usato per tutte le simulazioni in questa tesi. Vengono quindi descritti, e discussi a livello qualitativo, i passaggi effettuati nella simulazione: preparazione di una "supercella" del cristallo, localizzazione di un elettrone in eccesso e formazione del polarone. Alla fine della modellizzazione è stata analizzata la densità di stati del cristallo ed è stato trovato uno stato localizzato compatibile con la formazione del polarone. Altri valori stimati nella simulazione sono la distorsione media del reticolo intorno al polarone, la magnetizzazione del sito interessato e l'energia di formazione del polarone

When Should We Adopt EUS-Guided Radiofrequency Ablation in Pancreatic Neuroendocrine Tumors?

Pancreatic neuroendocrine neoplasms (PanNENs) are rare and heterogeneous diseases that account for less than 2% of all cases of pancreatic cancer and only 30% of digestive neuroendocrine neoplasia, even if their incidence and prevalence continue to rise globally [...]

Forecasting People Trajectories and Head Poses by Jointly Reasoning on Tracklets and Vislets

In this work, we explore the correlation between people trajectories and their head orientations. We argue that people trajectory and head pose forecasting can be modelled as a joint problem. Recent approaches on trajectory forecasting leverage short-term trajectories (aka tracklets) of pedestrians to predict their future paths. In addition, sociological cues, such as expected destination or pedestrian interaction, are often combined with tracklets. In this paper, we propose MiXing-LSTM (MX-LSTM) to capture the interplay between positions and head orientations (vislets) thanks to a joint unconstrained optimization of full covariance matrices during the LSTM backpropagation. We additionally exploit the head orientations as a proxy for the visual attention, when modeling social interactions. MX-LSTM predicts future pedestrians location and head pose, increasing the standard capabilities of the current approaches on long-term trajectory forecasting. Compared to the state-of-the-art, our approach shows better performances on an extensive set of public benchmarks. MX-LSTM is particularly effective when people move slowly, i.e. the most challenging scenario for all other models. The proposed approach also allows for accurate predictions on a longer time horizon.Comment: Accepted at IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE 2019. arXiv admin note: text overlap with arXiv:1805.0065

Efficient calibration of four wheel industrial AGVs

In this paper, we propose a novel method for extrinsic and intrinsic automatic calibration of four wheel industrial Automated Guided Vehicles (AGVs) compliant with Ackermann and Dual Drive kinematics. For each kinematic model the algorithm estimates the trajectories measured by an on-board sensor and the expected ones given the state of the wheels. The estimation exploits the model equations derived in this work which constrain calibration parameters and measurements from wheel encoders and sensor odometry. The parameter values are computed through closed-form solutions of least-square estimation. The method has been implemented on Programmable Logic Controllers and tested on industrial AGVs. The developed procedure computes the parameters in about 10−15 minutes, a significant improvement compared with one hour or more required by manual AGV calibration. Experiments with AGVs of various sizes in a warehouse have assessed the accuracy and stability of the proposed approach. The position accuracy achieved by AGVs calibrated with the proposed method is higher than the one achieved by manual calibration

(2662) Proposal to reject the name Hypochaeris urens (Asteraceae)

In order to avoid a disadvantageous nomenclatural change (Art. 56.1 of the ICN) entailed by the strict application of the rules, and to promote nomenclatural stability in the most parsimonious way, we here propose the rejection, under Art. 56, of the name Hypochaeris urens

Seismic Performance of Dual Systems with BRBs under Mainshock-Aftershock Sequences

Buckling-restrained braces (BRBs) are employed in new constructions and in the retrofitting of existing frames. They provide additional strength and stiffness to buildings, together with high and stable energy dissipation capacity. BRBs can fail due to excessive maximum and/or cumulative ductility demands. In addition, the use of BRBs can result in large residual drifts in the structure due to their low post-elastic hardening. Moreover, in seismic-prone regions, structures are usually subjected to mainshock-aftershocks (MS-AS) earthquake sequences, often leaving no time for repair or retrofit between events. Ductility demand accumulation and/or residual drifts induced by the MS can affect the structural performance during the following AS. The present study addressed the abovementioned issues by first investigating an optimal design procedure for steel dual systems in which conventional BRB frames are combined with moment-resisting frames. The latter are designed to behave elastically to enhance the self-centering capability of the structure and limit soft-story mechanisms. The design procedure is first presented and applied to a case-study building. The seismic performance of the latter is assessed by means of sequential Cloud Analysis. Both real and artificial MS-AS sequences are used to derive system fragility curves. Results show that the BRBs capacity can be potentially affected by multiple earthquakes, which cause accumulation of plastic strains within the devices. However, the preliminary results show that when accounting for real MS-AS sequences, ASs do not significantly increase the cumulative ductility demands in BRBs.The support of Prof. Katsuichiro Goda that provided real MS-AS sequences, as well as the fruitful discussions on the detailed BRBs OpenSees modeling with Prof. Alessandro Zona and Prof. Quan Gu are gratefully acknowledged

Bioprosthetic Valve Fracture After TAVR Complicated by Balloon Rupture: Bail-Out TAVR in TAVR in SAVR

Transcatheter aortic valve replacement in surgical aortic valve is a safe and effective procedure to treat patients with failed bioprosthetic surgical valves at high risk for reoperation. Performing bioprosthetic valve fracture has been shown to improve postprocedural hemodynamics of TAVR in surgical aortic valve replacement. However, specific complications related to valve fracture are becoming more common. (Level of Difficulty: Advanced.)