We propose an alternative generator architecture for generative adversarialnetworks, borrowing from style transfer literature. The new architecture leadsto an automatically learned, unsupervised separation of high-level attributes(e.g., pose and identity when trained on human faces) and stochastic variationin the generated images (e.g., freckles, hair), and it enables intuitive,scale-specific control of the synthesis. The new generator improves thestate-of-the-art in terms of traditional distribution quality metrics, leads todemonstrably better interpolation properties, and also better disentangles thelatent factors of variation. To quantify interpolation quality anddisentanglement, we propose two new, automated methods that are applicable toany generator architecture. Finally, we introduce a new, highly varied andhigh-quality dataset of human faces.
The dotnet aspnet-codegenerator command runs the ASP.NET Core scaffolding engine. Running the dotnet aspnet-codegenerator command is required to scaffold from the command line or when using Visual Studio Code. The command isn't required to use scaffolding with Visual Studio, which includes the scaffolding engine by default.
By default the architecture of the .NET binaries to install represents the currently running OS architecture. To specify a different OS architecture, see dotnet tool install, --arch option.For more information, see GitHub issue dotnet/AspNetCore.Docs #29262.
It may be necessary to uninstall the ASP.NET Core code generator tool to resolve problems. For example, if you installed a preview version of the tool, uninstall it before installing the released version.
The logical architecture model describes the behavior of the mobile robot system for simulation: trajectory generator, trajectory follower, motor controller, sensor algorithm, and robot and environment. The connections represent the interactions in the system. Open the logical architecture model without any behaviors, double-click the file or run this command.
The architecture model describes the behavior of the robot, but no behavior is actually added to the architecture yet. By adding Simulink or Stateflow behavior, the logical architecture can also be simulated.
Create a new behavior based on the interface of a component. If a model or subsystem file already exists for the behavior, use Link To Model to link to the exisiting model or subsystem. To create new subsystem reference behavior for the Motor Controller component, right-click and select Create Simulink Behavior, or, on the toolstrip, click Create Simulink Behavior. For more information, see Implement Component Behavior Using Simulink.
You can create Simulink behaviors using mulitiple methods: Subsystem, Subsystem Reference, and Model Reference. Use Subsystem to create a subsystem component behavior that is part of the parent architecture model. Use the Subsystem Reference or Model Reference option to save the behavior as a separate artifact and reuse the behavior. Physical ports can only cross subsystem boundaries, so for physical systems, Subsystem Reference or Subsystem are recommended.
If you already have a behavior defined in a model file or subsystem file, use Link To Model to link a component to the corresponding file. On the toolstrip, click Link to Model, or right-click the Environment component and select Link to Model to link to the Environment.slx subsystem file.
The Robot Body and Environment are Simulink subsystem reference components that support physical ports. The Trajectory Generator is a Simulink subsystem component that also supports physical ports. The Trajectory Follower and Motion Controller components are represented as Simulink models linked to the components as referenced models.
A behavior algorithm is created based on port information only. When designing a logical architecture, you can set the interface of the port to define the information in more detail. For example, if you know that 800 x 600 RGB images captured at 24 frames per second are transferred from the camera sensor, then you can set the corresponding port interfaces accordingly to ensure efficient data transfer. For more information about setting interfaces, see Define Port Interfaces Between Components.
Once behavior models are linked, you can simulate the architecture model just like any other Simulink model by clicking Run. Simulation verifies requirements such as Transportation, Collision Avoidance, and Path Generation.
Finding molecules with desired characteristics is a key aspect of drug discovery [1]. Advances in the field have led to a variety of approaches for discovering promising compounds [2]. Specifically, methods like enumerated virtual libraries and de novo drug design are gaining attention, as they expand the search into a larger chemical space than existing physical compound libraries. This enhances the probability of finding drug candidates with specific desired properties and increases chemical diversity.
Over the past decade, a variety of generative models for de novo drug design have been published [3]. These models are trained to generate molecules based on a training set and are sampled to create new molecules. When reinforcement learning is incorporated into generative models, they can also be used to generate compounds that fulfill specific objectives. For the majority of de novo generators, molecules are represented by the Simplified Molecular-Input Line-Entry System (SMILES) [4, 5]. This is the case because SMILES and other molecular line notations are linear and therefore compatible with well-established generative models from the field of natural language processing (NLP) [6]. Previous research has shown the applicability of recurrent neural networks (RNNs), autoencoders, generative adversarial networks (GANs), and other generative models [7, 8].
A disadvantage of using SMILES and similar molecular line notations is that the generated sequences can be invalid. A valid SMILES sequence needs to adhere to specific syntax rules and also be chemically correct. The validity of different generative models has been compared in the GuacaMol benchmark, a standardized evaluation framework for generative models [9]. This showed that a general RNN-based model has a percentage of invalid outputs of around 4%. For generative autoencoders, the invalid rate was higher with around 15% invalid SMILES. With regards to generative variational autoencoders (VAE), the validity of outputs has also been reported to vary more, exemplifying the difficulty of sampling a continuous space [10]. The main disadvantage of these invalid outputs is that they cannot be progressed, therefore random samples of the chemical space will be absent or a bias might even be introduced towards molecules that are easier to correctly generate.
Therefore, considerable efforts have been made to increase the validity of generated molecules. To this end, different molecular line representations like DeepSMILES and SELF-referencing Embedded Strings (SELFIES) have been designed, but not widely adopted [11, 12]. In addition to this, graph representations can be used that directly represent molecules as graphs [13]. An advantage of graph-based models is that they almost exclusively generate valid outputs [14]. However, graph-based models are more challenging to apply because they have a higher computational cost and a lower generation speed [15,16,17]. Another approach that has been used to increase the number of valid outputs of VAEs, is to apply context-free grammar and attribute grammar [18, 19]. However, these approaches have the disadvantage that they reduce the search space. Theoretically, invalid SMILES sequences could also be corrected using translator models as used in the field of grammatical error correction (GEC) [20]. These types of models have an encoder-decoder architecture and can be trained to translate sequences into other sequences. Interestingly, Zheng et al. already showed that the principles from this field can be applied to correct syntax mistakes in short SMILES sequences, in the context of molecular building blocks [21]. In other SMILES-based tasks, translator models have also been successfully applied [22,23,24].
Although extensive research has been carried out on reducing the number of invalid outputs, no previous study has investigated the potential of these incorrect outputs. These outputs could be a useful source for the generation of new molecules and increase generator efficiency. In addition to this, it is probable that errors occur more frequently in more complex or longer sequences [25]. Therefore, the objective of this study is to fix these incorrect sequences and analyze the resulting molecules. Additionally, SMILES correction could offer a new approach to de novo drug design, in which the chemical space around existing molecules is expanded by introducing and fixing errors.
To train the SMILES corrector, a data set with pairs of invalid and valid SMILES was created. The number of errors introduced into the valid SMILES was varied to explore the potential benefits of training with multiple errors. The best-performing SMILES corrector was then used to correct invalid outputs from four de novo generation case studies: a general RNN, a VAE, a GAN and a conditional RNN model. Using chemical similarity and property distributions, the resulting fixed molecules were then compared to the training set and to molecules originally generated by the four de novo models. Lastly, the SMILES corrector was used to correct mistakes introduced into selective Aurora kinase B inhibitors to evaluate if local sequence exploration can be used to expand the nearby chemical space. Taken together, the work presented here provides the first exploration of the potential of invalid molecular representations for de novo drug design.
For the target-directed case study, a data set was created to train and evaluate the predictor models. To this end, high and medium-quality activity data was collected for human Aurora kinase A (AURKA) (UniProt accession O14965) and human Aurora kinase B (AURKB) (UniProt accession Q96GD4) from the Papyrus data set. The data set for AURKA consisted of 1232 bioactivity data points with pChEMBL values ranging from 3.4 to 11.0. The data set for AURKB consisted of 1131 bioactivity data points with pChEMBL values ranging from 4.1 to 11.0. For the selectivity window model, an additional data set was created with compounds with experimental Ki values for both of the targets [35]. This data set consisted of 849 relative affinity values ranging from -1.6 (indicating selectivity towards AURKA) to 3.0 (indicating selectivity towards AURKB).
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