75 research outputs found
Anomalous magnetohydrodynamics with temperature-dependent electric conductivity and application to the global polarization
We have derived the solutions of the relativistic anomalous
magnetohydrodynamics with longitudinal Bjorken boost invariance and transverse
electromagnetic fields in the presence of temperature or energy density
dependent electric conductivity. We consider the equations of states in a high
temperature limit or in a high chiral chemical potential limit. We obtain both
perturbative analytic solutions up to the order of \hbar and numerical
solutions in our configurations of initial electromagnetic fields and Bjorken
flow velocity. Our results show that the temperature or energy density
dependent electric conductivity plays an important role to the decaying of the
energy density and electromagnetic fields. We also implement our results to the
splitting of global polarization for \Lambda and \bar{\Lambda} hyperons induced
by the magnetic fields. Our results for the splitting of global polarization
disagree with the experimental data in low energy collisions, which implies
that the contribution from gradient of chemical potential may dominate in the
low energy collisions
Simulation Design of a Tomato Picking Manipulator
Simulation is an important way to verify the feasibility of design parameters and schemes for robots. Through simulation, this paper analyzes the effectiveness of the design parameters selected for a tomato picking manipulator, and verifies the rationality of the manipulator in motion planning for tomato picking. Firstly, the basic parameters and workspace of the manipulator were determined based on the environment of a tomato greenhouse; the workspace of the lightweight manipulator was proved as suitable for the picking operation through MATLAB simulation. Next, the maximum theoretical torque of each joint of the manipulator was solved through analysis, the joint motors were selected reasonably, and SolidWorks simulation was performed to demonstrate the rationality of the material selected for the manipulator and the strength design of the joint connectors. After that, the trajectory control requirements of the manipulator in picking operation were determined in view of the operation environment, and the feasibility of trajectory planning was confirmed with MATLAB. Finally, a motion control system was designed for the manipulator, according to the end trajectory control requirements, followed by the manufacturing of a prototype. The prototype experiment shows that the proposed lightweight tomato picking manipulator boasts good kinematics performance, and basically meets the requirements of tomato picking operation: the manipulator takes an average of 21 s to pick a tomato, and achieves a success rate of 78.67%
ReRoGCRL: Representation-based Robustness in Goal-Conditioned Reinforcement Learning
While Goal-Conditioned Reinforcement Learning (GCRL) has gained attention,
its algorithmic robustness against adversarial perturbations remains
unexplored. The attacks and robust representation training methods that are
designed for traditional RL become less effective when applied to GCRL. To
address this challenge, we first propose the Semi-Contrastive Representation
attack, a novel approach inspired by the adversarial contrastive attack. Unlike
existing attacks in RL, it only necessitates information from the policy
function and can be seamlessly implemented during deployment. Then, to mitigate
the vulnerability of existing GCRL algorithms, we introduce Adversarial
Representation Tactics, which combines Semi-Contrastive Adversarial
Augmentation with Sensitivity-Aware Regularizer to improve the adversarial
robustness of the underlying RL agent against various types of perturbations.
Extensive experiments validate the superior performance of our attack and
defence methods across multiple state-of-the-art GCRL algorithms. Our tool
ReRoGCRL is available at https://github.com/TrustAI/ReRoGCRL.Comment: This paper has been accepted in AAAI24
(https://aaai.org/aaai-conference/
Mitochondrial Genome of an 8,400-Year-Old Individual from Northern China Reveals a Novel Sub-Clade under C5d
Ancient DNA studies have always refreshed our understanding of the human past that can’t be tracked by modern DNA alone. Until recently, ancient mitochondrial genomic studies in East Asia are still very limited. Here, we retrieved the whole mitochondrial genome of an 8,400-year- old individual from Inner Mongolia, China. Phylogenetic analyses show that the individual belongs to a previously undescribed clade under haplogroup C5d that was most probably originated in northern Asia and may have a very low frequency in extant populations that is not yet sampled. We further characterized the demographic history of mitochondrial haplogroups C5 and C5d, and found that C5 experienced a sharp increase in population size starting from around 4,000 years before present (BP). The time when intensive millet farming was built by populations who are associated with the lower Xiajiadian culture and was widely adopted in northern China. We caution that people related to haplogroup C5 may added this farming technology to their original way of life and that the various subsistence may provide abundant food sources and may further contribute to the increase of the population size
Ancient mitochondrial genomes reveal extensive genetic influence of the steppe pastoralists in Western Xinjiang
The population prehistory of Xinjiang has been a hot topic among geneticists, linguists, and archaeologists. Current ancient DNA studies in Xinjiang exclusively suggest an admixture model for the populations in Xinjiang since the early Bronze Age. However, almost all of these studies focused on the northern and eastern parts of Xinjiang; the prehistoric demographic processes that occurred in western Xinjiang have been seldomly reported. By analyzing complete mitochondrial sequences from the Xiabandi (XBD) cemetery (3,500–3,300 BP), the up-to-date earliest cemetery excavated in western Xinjiang, we show that all the XBD mitochondrial sequences fall within two different West Eurasian mitochondrial DNA (mtDNA) pools, indicating that the migrants into western Xinjiang from west Eurasians were a consequence of the early expansion of the middle and late Bronze Age steppe pastoralists (Steppe_MLBA), admixed with the indigenous populations from Central Asia. Our study provides genetic links for an early existence of the Indo-Iranian language in southwestern Xinjiang and suggests that the existence of Andronovo culture in western Xinjiang involved not only the dispersal of ideas but also population movement.Introduction Materials and methods - Archaeological Background, Sampling, and Sequencing - Sequence Mapping and Mitochondrial DNA Haplogroup Determination - Analysis of Xiabandi Mitochondrial DNA Genomes Results - Mitochondrial DNA Authentication and Contamination Assessment - Major Bronze Age Steppe Pastoralist Origin of the Xiabandi Mitochondrial Haplogroups - Expansion of the Bronze Age Steppe Pastoralists as a Dynamic Process to Form the Genetic Landscape of Xiabandi Individuals Discussion Conclusion
Adaptive Deep Neural Network Inference Optimization with EENet
Well-trained deep neural networks (DNNs) treat all test samples equally
during prediction. Adaptive DNN inference with early exiting leverages the
observation that some test examples can be easier to predict than others. This
paper presents EENet, a novel early-exiting scheduling framework for multi-exit
DNN models. Instead of having every sample go through all DNN layers during
prediction, EENet learns an early exit scheduler, which can intelligently
terminate the inference earlier for certain predictions, which the model has
high confidence of early exit. As opposed to previous early-exiting solutions
with heuristics-based methods, our EENet framework optimizes an early-exiting
policy to maximize model accuracy while satisfying the given per-sample average
inference budget. Extensive experiments are conducted on four computer vision
datasets (CIFAR-10, CIFAR-100, ImageNet, Cityscapes) and two NLP datasets
(SST-2, AgNews). The results demonstrate that the adaptive inference by EENet
can outperform the representative existing early exit techniques. We also
perform a detailed visualization analysis of the comparison results to
interpret the benefits of EENet
GeoGauss: Strongly Consistent and Light-Coordinated OLTP for Geo-Replicated SQL Database
Multinational enterprises conduct global business that has a demand for
geo-distributed transactional databases. Existing state-of-the-art databases
adopt a sharded master-follower replication architecture. However, the
single-master serving mode incurs massive cross-region writes from clients, and
the sharded architecture requires multiple round-trip acknowledgments (e.g.,
2PC) to ensure atomicity for cross-shard transactions. These limitations drive
us to seek yet another design choice. In this paper, we propose a strongly
consistent OLTP database GeoGauss with full replica multi-master architecture.
To efficiently merge the updates from different master nodes, we propose a
multi-master OCC that unifies data replication and concurrent transaction
processing. By leveraging an epoch-based delta state merge rule and the
optimistic asynchronous execution, GeoGauss ensures strong consistency with
light-coordinated protocol and allows more concurrency with weak isolation,
which are sufficient to meet our needs. Our geo-distributed experimental
results show that GeoGauss achieves 7.06X higher throughput and 17.41X lower
latency than the state-of-the-art geo-distributed database CockroachDB on the
TPC-C benchmark
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