255 research outputs found
Interpretable Sequence Classification Via Prototype Trajectory
We propose a novel interpretable recurrent neural network (RNN) model, called
ProtoryNet, in which we introduce a new concept of prototype trajectories.
Motivated by the prototype theory in modern linguistics, ProtoryNet makes a
prediction by finding the most similar prototype for each sentence in a text
sequence and feeding an RNN backbone with the proximity of each of the
sentences to the prototypes. The RNN backbone then captures the temporal
pattern of the prototypes, to which we refer as prototype trajectories. The
prototype trajectories enable intuitive, fine-grained interpretation of how the
model reached to the final prediction, resembling the process of how humans
analyze paragraphs. Experiments conducted on multiple public data sets reveal
that the proposed method not only is more interpretable but also is more
accurate than the current state-of-the-art prototype-based method. Furthermore,
we report a survey result indicating that human users find ProtoryNet more
intuitive and easier to understand, compared to the other prototype-based
methods
Federated Learning on Adaptively Weighted Nodes by Bilevel Optimization
We propose a federated learning method with weighted nodes in which the
weights can be modified to optimize the model's performance on a separate
validation set. The problem is formulated as a bilevel optimization where the
inner problem is a federated learning problem with weighted nodes and the outer
problem focuses on optimizing the weights based on the validation performance
of the model returned from the inner problem. A communication-efficient
federated optimization algorithm is designed to solve this bilevel optimization
problem. Under an error-bound assumption, we analyze the generalization
performance of the output model and identify scenarios when our method is in
theory superior to training a model only locally and to federated learning with
static and evenly distributed weights
Error Compensation of Single-Qubit Gates in a Surface Electrode Ion Trap Using Composite Pulses
The fidelity of laser-driven quantum logic operations on trapped ion qubits
tend to be lower than microwave-driven logic operations due to the difficulty
of stabilizing the driving fields at the ion location. Through stabilization of
the driving optical fields and use of composite pulse sequences, we demonstrate
high fidelity single-qubit gates for the hyperfine qubit of a
ion trapped in a microfabricated surface electrode ion
trap. Gate error is characterized using a randomized benchmarking protocol, and
an average error per randomized Clifford group gate of is
measured. We also report experimental realization of palindromic pulse
sequences that scale efficiently in sequence length
Biochemical Characterization of Enzyme Fidelity of Influenza A Virus RNA Polymerase Complex
It is widely accepted that the highly error prone replication process of influenza A virus (IAV), together with viral genome assortment, facilitates the efficient evolutionary capacity of IAV. Therefore, it has been logically assumed that the enzyme responsible for viral RNA replication process, influenza virus type A RNA polymerase (IAV Pol), is a highly error-prone polymerase which provides the genomic mutations necessary for viral evolution and host adaptation. Importantly, however, the actual enzyme fidelity of IAV RNA polymerase has never been characterized.Here we established new biochemical assay conditions that enabled us to assess both polymerase activity with physiological NTP pools and enzyme fidelity of IAV Pol. We report that IAV Pol displays highly active RNA-dependent RNA polymerase activity at unbiased physiological NTP substrate concentrations. With this robust enzyme activity, for the first time, we were able to compare the enzyme fidelity of IAV Pol complex with that of bacterial phage T7 RNA polymerase and the reverse transcriptases (RT) of human immunodeficiency virus (HIV-1) and murine leukemia virus (MuLV), which are known to be low and high fidelity enzymes, respectively. We observed that IAV Pol displayed significantly higher fidelity than HIV-1 RT and T7 RNA polymerase and equivalent or higher fidelity than MuLV RT. In addition, the IAV Pol complex showed increased fidelity at lower temperatures. Moreover, upon replacement of Mg(++) with Mn(++), IAV Pol displayed increased polymerase activity, but with significantly reduced processivity, and misincorporation was slightly elevated in the presence of Mn(++). Finally, when the IAV nucleoprotein (NP) was included in the reactions, the IAV Pol complex exhibited enhanced polymerase activity with increased fidelity.Our study indicates that IAV Pol is a high fidelity enzyme. We envision that the high fidelity nature of IAV Pol may be important to counter-balance the multiple rounds of IAV genome amplification per infection cycle, which provides IAV Pol with ample opportunities to generate and amplify genomic founder mutations, and thus achieve optimal viral mutagenesis for its evolution
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