302 research outputs found
Quasi-B-mode generated by high-frequency gravitational waves and corresponding perturbative photon fluxes
Interaction of very low-frequency primordial(relic) gravitational waves(GWs)
to cosmic microwave background(CMB) can generate B-mode polarization. Here, for
the first time we point out that the electromagnetic(EM) response to
high-frequency GWs(HFGWs) would produce quasi-B-mode distribution of the
perturbative photon fluxes, and study the duality and high complementarity
between such two B-modes. Based on this quasi-B-mode in HFGWs, it is shown that
the distinguishing and observing of HFGWs from the braneworld would be quite
possible due to their large amplitude, higher frequency and very different
physical behaviors between the perturbative photon fluxes and background
photons, and the measurement of relic HFGWs may also be possible though face to
enormous challenge.Comment: 22 pages, 6 figures, research articl
Experimental and physical model of the melting zone in the interface of the explosive cladding bar
AbstractLocal melting zone encountered in sections of the cladding interface is a distinguished phenomenon of the explosive cladding technique. The thickness and morphology of the melting zone in the Ti/NiCr explosive cladding bar are investigated by means of optical microscopy. Results show that the distribution of the melting zone in the interface of the Ti/NiCr explosive cladding bar is uniform and axisymmetric, and boundaries of the melting zone are circular arcs, whose center points to the center of the NiCr bar. The bamboo-shaped cracks generate in the melting zone. The thickness of the melting zone decreases with reducing of the stand-off distance and the thickness of the explosive. A physical model of the melting zone in the interface of the explosive cladding bar is proposed
Phalanx: A Practical Byzantine Ordered Consensus Protocol
Byzantine fault tolerance (BFT) consensus is a fundamental primitive for
distributed computation. However, BFT protocols suffer from the ordering
manipulation, in which an adversary can make front-running. Several protocols
are proposed to resolve the manipulation problem, but there are some
limitations for them. The batch-based protocols such as Themis has significant
performance loss because of the use of complex algorithms to find strongly
connected components (SCCs). The timestamp-based protocols such as Pompe have
simplified the ordering phase, but they are limited on fairness that the
adversary can manipulate the ordering via timestamps of transactions. In this
paper, we propose a Byzantine ordered consensus protocol called Phalanx, in
which transactions are committed by anchor-based ordering strategy. The
anchor-based strategy makes aggregation of the Lamport logical clock of
transactions on each participant and generates the final ordering without
complex detection for SCCs. Therefore, Phalanx has achieved satisfying
performance and performs better in resisting ordering manipulation than
timestamp-based strategy
HAL: Improved Text-Image Matching by Mitigating Visual Semantic Hubs
The hubness problem widely exists in high-dimensional embedding space and is
a fundamental source of error for cross-modal matching tasks. In this work, we
study the emergence of hubs in Visual Semantic Embeddings (VSE) with
application to text-image matching. We analyze the pros and cons of two widely
adopted optimization objectives for training VSE and propose a novel
hubness-aware loss function (HAL) that addresses previous methods' defects.
Unlike (Faghri et al.2018) which simply takes the hardest sample within a
mini-batch, HAL takes all samples into account, using both local and global
statistics to scale up the weights of "hubs". We experiment our method with
various configurations of model architectures and datasets. The method exhibits
exceptionally good robustness and brings consistent improvement on the task of
text-image matching across all settings. Specifically, under the same model
architectures as (Faghri et al. 2018) and (Lee at al. 2018), by switching only
the learning objective, we report a maximum R@1improvement of 7.4% on MS-COCO
and 8.3% on Flickr30k.Comment: AAAI-20 (to appear
Composing MPC with LQR and Neural Network for Amortized Efficiency and Stable Control
Model predictive control (MPC) is a powerful control method that handles
dynamical systems with constraints. However, solving MPC iteratively in real
time, i.e., implicit MPC, remains a computational challenge. To address this,
common solutions include explicit MPC and function approximation. Both methods,
whenever applicable, may improve the computational efficiency of the implicit
MPC by several orders of magnitude. Nevertheless, explicit MPC often requires
expensive pre-computation and does not easily apply to higher-dimensional
problems. Meanwhile, function approximation, although scales better with
dimension, still requires pre-training on a large dataset and generally cannot
guarantee to find an accurate surrogate policy, the failure of which often
leads to closed-loop instability. To address these issues, we propose a
triple-mode hybrid control scheme, named Memory-Augmented MPC, by combining a
linear quadratic regulator, a neural network, and an MPC. From its standard
form, we further derive two variants of such hybrid control scheme: one
customized for chaotic systems and the other for slow systems. The proposed
scheme does not require pre-computation and can improve the amortized running
time of the composed MPC with a well-trained neural network. In addition, the
scheme maintains closed-loop stability with any neural networks of proper input
and output dimensions, alleviating the need for certifying optimality of the
neural network in safety-critical applications.Comment: 13 pages, 10 figures, 2 table
Genetic Polymorphisms of Molecules Associated with Innate Immune Responses, TRL2 and MBL2 Genes in Japanese Subjects with Functional Dyspepsia
Inflammatory changes in the gastric mucosa are commonly observed in Japanese patients with functional dyspepsia (FD). However, detailed data regarding the possible association between the genetic factors of inflammation related molecules and FD are not available. Toll like receptor 2 (TLR2) and mannan-binding lectin (MBL) protein play important roles in the innate immune activation. We aimed to clarify the association between common polymorphisms of TLR2 and MBL2 genes with FD in Japanese subjects. TLR2 −196 to −174 del and MBL2 codon54 G/A polymorphisms were genotyped in 111 FD patients according to Rome III criteria and 106 asymptomatic controls. Non-significant correlation was found between TLR2 and MBL2 polymorphisms with FD. However, in Helicobacter pylori (H. pylori) positives, we found significant inverse association between TLR2 −196 to −174 del carrier and FD among H. pylori positive subjects (Adjusted odds ratio (OR) = 0.48, 95% confidence interval (CI) = 0.23–0.996, p = 0.0488). We also found significant inverse association between the same genotype with postprandial distress syndrome (PDS) among H. pylori positive subjects (Adjusted OR = 0.22, 95% CI = 0.07–0.69, p = 0.0099). Our data suggest that TLR2 −196 to −174 del carriers’s status but not MBL2 codon54 G/A is inversely related to the risk with FD in H. pylori-infected subjects
Comprehensive Analysis of Codon Usage Patterns in Chinese Porcine Circoviruses Based on Their Major Protein-Coding Sequences
Porcine circoviruses (PCVs) are distributed in swine herds worldwide and represent a threat to the health of domestic pigs and the profits of the swine industry. Currently, four PCV species, including PCV-1, PCV-2, PCV-3 and PCV-4, have been identified in China. Considering the ubiquitous characteristic of PCVs, the new emerged PCV-4 and the large scale of swine breeding in China, an overall analysis on codon usage bias for Chinese PCV sequences was performed by using the major proteins coding sequences (ORF1 and ORF2) to better understand the relationship of these viruses with their host. The data from genome nucleotide frequency composition and relative synonymous codon usage (RSCU) analysis revealed an overrepresentation of AT pair and the existence of a certain codon usage bias in all PCVs. However, the values of an effective number of codons (ENC) revealed that the bias was of low magnitude. Principal component analysis, ENC-plot, parity rule two analysis and correlation analysis suggested that natural selection and mutation pressure were both involved in the shaping of the codon usage patterns of PCVs. However, a neutrality plot revealed a stronger effect of natural selection than mutation pressure on codon usage patterns. Good host adaptation was also shown by the codon adaptation index analysis for all these viruses. Interestingly, obtained data suggest that PCV-4 might be more adapted to its host compared to other PCVs. The present study obtained insights into the codon usage pattern of PCVs based on ORF1 and ORF2, which further helps the understanding the molecular evolution of these swine viruses.info:eu-repo/semantics/publishedVersio
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