Deep Neuroevolution of Recurrent and Discrete World Models

Neural architectures inspired by our own human cognitive system, such as the recently introduced world models, have been shown to outperform traditional deep reinforcement learning (RL) methods in a variety of different domains. Instead of the relatively simple architectures employed in most RL experiments, world models rely on multiple different neural components that are responsible for visual information processing, memory, and decision-making. However, so far the components of these models have to be trained separately and through a variety of specialized training methods. This paper demonstrates the surprising finding that models with the same precise parts can be instead efficiently trained end-to-end through a genetic algorithm (GA), reaching a comparable performance to the original world model by solving a challenging car racing task. An analysis of the evolved visual and memory system indicates that they include a similar effective representation to the system trained through gradient descent. Additionally, in contrast to gradient descent methods that struggle with discrete variables, GAs also work directly with such representations, opening up opportunities for classical planning in latent space. This paper adds additional evidence on the effectiveness of deep neuroevolution for tasks that require the intricate orchestration of multiple components in complex heterogeneous architectures

Tuning the crystalline phases of poly(vinylidene fluoride) for capacitive energy storage applications

Radars, defibrillators, high energy lasers, power inverters in electric vehicles are all applications that require highly efficient capacitors having large discharged energy densities in their electronic circuits. Utilizing advanced plastics instead of ceramics as dielectric medium in capacitors offer unique advantages such as flexibility, ease of processing, reliability and, moreover, the ability to withstand high voltages. In this respect, poly(vinylidene fluoride) (PVDF) is an excellent choice to serve as dielectric medium due to its high dielectric constant and high electrical strength, both contributing to high energy density materials. However, at high electric fields PVDF crystals transform irreversible to the ferroelectric crystalline phase, leading to drastically reduced discharged energy densities due to ferroelectric losses. Nevertheless, literature prescribes that these ferroelectric crystals can be beneficial for capacitive energy storage applications when they are well-isolated in nanodomains. In this dissertation, distinct polymeric architectures based on (PVDF) are investigated to optimize the crystallization behavior of PVDF for enhanced dielectric properties. As such, block copolymer self-assembly proves to be a viable method to obtain isolated ferroelectric crystals in nanospheres, while also the temperature dependent crystalline phase transformations of poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-co-TrFE)) copolymers are studied. In the second part of the dissertation, it is discussed that vinyl alcohol (VA) can be incorporated in the PVDF and P(VDF-co-TrFE) backbone, giving ferroelectric P(VDF-co-VA) copolymers and relaxor ferroelectric P(VDF-ter-TrFE-ter-VA) terpolymers. The introduction of VA in the polymer backbone allows these polymers to be crosslinked, leading to novel polymers with appealing dielectric properties. Concerns regarding ferroelectric losses are mitigated, while the discharge energy densities and efficiencies are increased, highlighting the high potential of these materials for capacitive energy storage applications

Model-based optimisation and control strategy for the primary drying phase of a lyophilisation process

The standard operation of a batch freeze-dryer is protocol driven. All freeze-drying phases (i.e., freezing, primary and secondary drying) are programmed sequentially at fixed time points and within each phase critical process parameters (CPPs) are typically kept constant or linearly interpolated between two setpoints. This way of operating batch freeze-dryers is shown to be time consuming and inefficient. A model-based optimisation and real-time control strategy that includes model output uncertainty could help in accelerating the primary drying phase while controlling the risk of failure of the critical quality attributes (CQAs). In each iteration of the real-time control strategy, a design space is computed to select an optimal set of CPPs. The aim of the control strategy is to avoid product structure loss, which occurs when the sublimation interface temperature (Ti) exceeds the the collapse temperature (Tc) common during unexpected disturbances, while preventing the choked flow conditions leading to a loss of pressure control. The proposed methodology was experimentally verified when the chamber pressure and shelf fluid system were intentionally subjected to moderate process disturbances. Moreover, the end of the primary drying phase was predicted using both uncertainty analysis and a comparative pressure measurement technique. Both the prediction of Ti and end of primary drying were in agreement with the experimental data. Hence, it was confirmed that the proposed real-time control strategy is capable of mitigating the effect of moderate disturbances during batch freeze-drying

Innovations in Sub-National Government in Europe

Improvement in government is often rooted in decentralised layers of government. In this article the authors discuss the recent history of innovations in sub-national government in Europe. They focus on two general trends and developments. Cases of interesting practices and developments illustrate the general trends. For each general trend a distinction is made between two kinds of innovations: structural reforms and new ways of working within existing institutional settings. The first trend concerns changing relations between government, civil society and citizens, in response to the increased contestation of the nature of traditional representative democracy. Examples of structural reforms are: increased citizen participation, the expanded use of referenda and the introduction of the directly elected mayor. New ways of working are: forms of coproduction between the public sector and the third sector. The second trend described in this article is change within government itself, mainly the rise of ‘governance’ and changing administrative scales. Structural reforms take several forms: scale enlargement to enhance system capacity, scale reduction to enhance system capacity, scale enlargement to enhance citizen effectiveness, and scale reduction to enhance citizen effectiveness. Next to them, new ways of working can be observed within governments: cross-boarder co-operations, inter-municipal co-operations, and new forms of performance assessment and fiscal management. The authors conclude the article with a few challenges to both academics and governments.La mejora del gobierno se encuentra arraigada con frecuencia en los niveles descentralizados. En este artículo es el cambio dentro del gobierno mismo, principalmente la emergencia de la “gobernanza” y el cambio en el tamaño administrativo. Las reformas estructurales adoptan formas diversas: el aumento del tamaño para mejorar la capacidad del sistema, el aumento del tamaño para favorecer la participación ciudadana, y la reducción del tamaño para favorecer asimismo la participación ciudadana. Además, se advierten nuevas formas de acción dentro de los mismos gobiernos: cooperación transfronteriza, cooperación intermunicipal y nuevas formas de evaluación del rendimiento y de la gestión financiera. Los autores concluyen el artículo mencionando algunos desafíos para los académicos y para los gobiernos

Lithium and magnesium polymeric electrolytes prepared using poly(glycidyl ether)-based polymers with short grafted chains

Recently, poly(allyl glycidyl ether) (PAGE) has attracted great interest as a polymer electrolyte for Li-ion transport with conductivity values well above that of the benchmark polyethylene oxide polymer at temperatures below 60 °C. Here, we prepared lithium and magnesium polyelectrolytes by using two novel PAGE-based matrixes containing thioether and sulfone functionalities located in a short side chain inserted by the chemical post-functionalization of PAGE. The synthesized PAGEs, poly(2-(ethyl thio) propyl glycidyl ether) (PEthioPGE) and poly(2-(ethyl sulfone) propyl glycidyl ether) (PEsulfoPGE), were all amorphous at any temperature with Tg between-80 °C and-30 °C. These polymers were used to formulate electrolytes with different Li and Mg salts. The impact of the side chain, used salt and temperature on the ionic conductivity was studied in detail. Ionic conductivities as high as 5.1 × 10-4 S cm-1 at 90 °C can be achieved using PAGE-LiTFSI and PEthioPGE-LiTFSI, values comparable to that achieved using PEO-LiTFSI with identical salt loading. When LiCl is used, PEthioPGE outperforms all other polymers including PEO with the highest conductivity value at 90 °C (1.1 × 10-5 S cm-1). Moreover, the studied complexes with magnesium salts showed promising ionic conductivities, comparable to those achieved using lithium and up to 4.1 × 10-4 S cm-1 at 90 °C for PAGE-Mg(TFSI)2. The results presented here highlight the possibility of tuning the structures and the complexation properties of poly(glycidyl ether)-based electrolytes towards both lithium and magnesium ions

DNA looping by FokI: the impact of twisting and bending rigidity on protein-induced looping dynamics

Protein-induced DNA looping is crucial for many genetic processes such as transcription, gene regulation and DNA replication. Here, we use tethered-particle motion to examine the impact of DNA bending and twisting rigidity on loop capture and release, using the restriction endonuclease FokI as a test system. To cleave DNA efficiently, FokI bridges two copies of an asymmetric sequence, invariably aligning the sites in parallel. On account of the fixed alignment, the topology of the DNA loop is set by the orientation of the sites along the DNA. We show that both the separation of the FokI sites and their orientation, altering, respectively, the twisting and the bending of the DNA needed to juxtapose the sites, have profound effects on the dynamics of the looping interaction. Surprisingly, the presence of a nick within the loop does not affect the observed rigidity of the DNA. In contrast, the introduction of a 4-nt gap fully relaxes all of the torque present in the system but does not necessarily enhance loop stability. FokI therefore employs torque to stabilise its DNA-looping interaction by acting as a ‘torsional’ catch bond