Synchronizing noisy nonidentical oscillators by transient uncoupling

Synchronization is the process of achieving identical dynamics among coupled identical units. If the units are different from each other, their dynamics cannot become identical; yet, after transients, there may emerge a functional relationship between them -- a phenomenon termed "generalized synchronization." Here, we show that the concept of transient uncoupling, recently introduced for synchronizing identical units, also supports generalized synchronization among nonidentical chaotic units. Generalized synchronization can be achieved by transient uncoupling even when it is impossible by regular coupling. We furthermore demonstrate that transient uncoupling stabilizes synchronization in the presence of common noise. Transient uncoupling works best if the units stay uncoupled whenever the driven orbit visits regions that are locally diverging in its phase space. Thus, to select a favorable uncoupling region, we propose an intuitive method that measures the local divergence at the phase points of the driven unit's trajectory by linearizing the flow and subsequently suppresses the divergence by uncoupling

Defining and identifying the optimal embedding dimension of networks

Network embedding is a general-purpose machine learning technique that encodes network structure in vector spaces with tunable dimension. Choosing an appropriate embedding dimension -- small enough to be efficient and large enough to be effective -- is challenging but necessary to generate embeddings applicable to a multitude of tasks. Unlike most existing strategies that rely on performance maximization in downstream tasks, here we propose a principled method for the identification of an optimal dimension such that all structural information of a network is parsimoniously encoded. The method is validated on various embedding algorithms and a large corpus of real-world networks. Estimated values of the optimal dimension in real-world networks suggest that efficient encoding in low-dimensional spaces is usually possible.Comment: 9 pages, 5 figures + Suppl. Ma

Numerical investigation of the effect of bed height and coefficient of restitution on the minimum fluidization velocity of a cylindrical fluidized bed.

Numerical simulation for 4 different ratios of initial bed heights (H) to base diameter (D), were performed; viz. 0.5, 1, 2 and 3. Glass beads of density 2600kg/m3 and with an average diameter of 550μm were used for all the simulations. Simulations were performed using the commercial CFD software, STAR-CCM+. The minimum fluidization velocity was identified by measuring pressure drop across the entire domain and found to remain same for all the above mentioned ratios. The present CFD results show excellent agreement with the experimental findings of Escudero & Heindel (2010)

Simulation of rectangular fluidised bed with Geldart D particles.

In this study, simulations are carried out using the Euler-Euler granular model in STAR-CCM+ for a gas-solid flow in a rectangular bubbling fluidized bed. The problem studied was announced as Small Scale Challenge Problem (SSCP-I) in 2013. Experiments for this problem were conducted by The Department of Energy's (DOE) National Energy Technology Laboratory (NETL). The objective of this numerical study is to evaluate the reliability of the kinetic theory based granular model (KTGF) in predicting the hydrodynamics of gas-solid flows. The experimental measurements of the bubbling fluidized bed investigated in this numerical study are 3"x9"x48". The bed material for the experiment is Geldart group D particles of uniform size and high sphericity. Simulations were performed for all the three gas superficial velocities (U = 2.19, 3.28 and 4.38 m/s) for which experiments were conducted. Results from numerical simulations are validated for vertical component of particle velocity, horizontal component of particle velocity, granular temperature and the mean axial pressure gradient. The effect of the treatment at wall boundaries and coefficient of restitution (particle-particle interactions) is studied on the results

An Eulerian–Eulerian formulation for erosion modelling: an alternate approach.

Sand is commonly produced besides petroleum fluids and it presents a major erosional hazard leading to pipe failures. Particle erosion is a complex process in which material is removed due to the repeated particle impacts. Conventionally, a CFD flow solver and computationally intensive lagrangian particle tracking sub–routines, known as Eulerian–Lagrangian (E–L) model, along with empirical erosion equations are used to predict the erosion rates. The present work introduces an Eulerian–Eulerian (E–E) approach in which the multiphase granular model resolves the solid phase and obviates the need of particles tracking. Particle–laden turbulent flow across a flow restrictor, based on an experimental study, is chosen for validation. Numerical experiments are done in Simcenter STAR–CCM+. Comparison with the experimental data demonstrate a good agreement and in particular, the E–E model yields reliable predictions of impact wear locations, erosion rates as those of E–L model. A 90° square bend is also simulated and comparison of erosion rates on the concave wall demonstrate that E–E model can be used as an alternate to computationally expensive approaches

Recency predicts bursts in the evolution of author citations

The citations process for scientific papers has been studied extensively. But while the citations accrued by authors are the sum of the citations of their papers, translating the dynamics of citation accumulation from the paper to the author level is not trivial. Here we conduct a systematic study of the evolution of author citations, and in particular their bursty dynamics. We find empirical evidence of a correlation between the number of citations most recently accrued by an author and the number of citations they receive in the future. Using a simple model where the probability for an author to receive new citations depends only on the number of citations collected in the previous 12-24 months, we are able to reproduce both the citation and burst size distributions of authors across multiple decades.Comment: 12 pages, 7 figure

Genome wide association study of uric acid in Indian population and interaction of identified variants with type 2 diabetes

Abnormal level of Serum Uric Acid (SUA) is an important marker and risk factor for complex diseases including Type 2 diabetes. Since genetic determinant of uric acid in Indians is totally unexplored, we tried to identify common variants associated with SUA in Indians using Genome Wide Association Study (GWAS). Association of five known variants in SLC2A9 and SLC22A11 genes with SUA level in 4,834 normoglycemics (1,109 in discovery and 3,725 in validation phase) was revealed with different effect size in Indians compared to other major ethnic population of the world. Combined analysis of 1,077 T2DM subjects (772 in discovery and 305 in validation phase) and normoglycemics revealed additional GWAS signal in ABCG2 gene. Differences in effect sizes of ABCG2 and SLC2A9 gene variants were observed between normoglycemics and T2DM patients. We identified two novel variants near long non-coding RNA genes AL356739.1 and AC064865.1 with nearly genome wide significance level. Meta-analysis and in silico replication in 11,745 individuals from AUSTWIN consortium improved association for rs12206002 in AL356739.1 gene to sub-genome wide association level. Our results extends association of SLC2A9, SLC22A11 and ABCG2 genes with SUA level in Indians and enrich the assemblages of evidence for SUA level and T2DM interrelationship

Common variants in CLDN2 and MORC4 genes confer disease susceptibility in patients with chronic pancreatitis

A recent Genome-wide Association Study (GWAS) identified association with variants in X-linked CLDN2 and MORC4 and PRSS1-PRSS2 loci with Chronic Pancreatitis (CP) in North American patients of European ancestry. We selected 9 variants from the reported GWAS and replicated the association with CP in Indian patients by genotyping 1807 unrelated Indians of Indo-European ethnicity, including 519 patients with CP and 1288 controls. The etiology of CP was idiopathic in 83.62% and alcoholic in 16.38% of 519 patients. Our study confirmed a significant association of 2 variants in CLDN2 gene (rs4409525—OR 1.71, P = 1.38 x 10-09; rs12008279—OR 1.56, P = 1.53 x 10-04) and 2 variants in MORC4 gene (rs12688220—OR 1.72, P = 9.20 x 10-09; rs6622126—OR 1.75, P = 4.04x10-05) in Indian patients with CP. We also found significant association at PRSS1-PRSS2 locus (OR 0.60; P = 9.92 x 10-06) and SAMD12-TNFRSF11B (OR 0.49, 95% CI [0.31–0.78], P = 0.0027). A variant in the gene MORC4 (rs12688220) showed significant interaction with alcohol (OR for homozygous and heterozygous risk allele -14.62 and 1.51 respectively, P = 0.0068) suggesting gene-environment interaction. A combined analysis of the genes CLDN2 and MORC4 based on an effective risk allele score revealed a higher percentage of individuals homozygous for the risk allele in CP cases with 5.09 fold enhanced risk in individuals with 7 or more effective risk alleles compared with individuals with 3 or less risk alleles (P = 1.88 x 10-14). Genetic variants in CLDN2 and MORC4 genes were associated with CP in Indian patients