Steady States of Sheared Active Nematics

2014 ◽  
Vol 6 (01) ◽  
pp. 75-86 ◽  
Author(s):  
Zhenlu Cui ◽  
Xiaoming Zeng ◽  
Jianbing Su
Keyword(s):  
Asymptotic Analysis ◽  
Numerical Simulations ◽  
Hydrodynamic Model ◽  
System Size ◽  
Complete Characterization ◽  
Steady States ◽  
Steady Shear

AbstractA continuum hydrodynamic model has been used to characterize flowing active nematics. The behavior of such a system subjected to a weak steady shear is analyzed. We explore the director structures and flow behaviors of the system in flow-aligning and flow tumbling regimes. Combining asymptotic analysis and numerical simulations, we extend previous studies to give a complete characterization of the steady states for both contractile and extensile particles in flow-aligning and flow-tumbling regimes. Another key prediction of this work is the role of the system size on the steady states of an active nematic system: if the system size is small, the velocity and the director angle files for both flow-tumbling contractile and extensile systems are similar to those of passive nematics; if the system is big, the velocity and the director angle files for flow-aligning contractile systems and tumbling extensile systems are akin to sheared passive cholesterics while they are oscillatory for flow-aligning extensile and tumbling contractile systems.

Aortic disease: Aneurysm and dissection—role of MSCT

2021 ◽  
pp. 771-780
Author(s):  
Rocío Hinojar ◽  
Raimund Erbel
Keyword(s):  
Aortic Disease ◽  
Complete Characterization ◽  
Unexpected Finding ◽  
Aortic Diseases ◽  
Aortic Pathology ◽  
Life Threatening ◽  
Excellent Spatial Resolution ◽  
Widespread Availability

Multislice computed tomography (MSCT) is currently the preferred modality for diagnosis and complete characterization of aortic pathology because of its widespread availability, rapidity, excellent spatial resolution, and excellent accuracy for all aortic segments and different aortic diseases. Aortic disease often remains undiagnosed until a life-threatening complication occurs or the disease is an unexpected finding on imaging studies performed for other purposes. MSCT allows the measurement of the aortic wall and dimension and the evaluation of morphologic features and surrounding structures, even in very sick or unstable patients. It provides not only accurate and highly reproducible aortic measurements but also the evaluation of the wall and contents of an aneurysm, including thrombus, and surrounding structures.

scholarly journals Complexity and polymorphisms for digraph constraint problems under some basic constructions

2016 ◽  
Vol 26 (07) ◽  
pp. 1395-1433 ◽  
Author(s):  
Marcel Jackson ◽  
Tomasz Kowalski ◽  
Todd Niven
Keyword(s):  
Directed Graphs ◽  
Complete Characterization ◽  
Constraint Satisfaction Problems ◽  
Local Consistency ◽  
First Order ◽  
Graph Theoretic ◽  
The Stability ◽  
Basic Graph

The role of polymorphisms in determining the complexity of constraint satisfaction problems is well established. In this context, we study the stability of CSP complexity and polymorphism properties under some basic graph theoretic constructions. As applications we observe a collapse in the applicability of algorithms for CSPs over directed graphs with both a total source and a total sink: the corresponding CSP is solvable by the “few subpowers algorithm” if and only if it is solvable by a local consistency check algorithm. Moreover, we find that the property of “strict width” and solvability by few subpowers are unstable under first-order reductions. The analysis also yields a complete characterization of the main polymorphism properties for digraphs whose symmetric closure is a complete graph.

DLTS: A Promising Technique for Understanding the Physics and Engineering of the Point Defects in Si and III-V Alloys

2007 ◽  
Vol 994 ◽  
Author(s):  
Aurangzeb Khan ◽  
Masafumi Yamaguchi
Keyword(s):  
Point Defects ◽  
Deep Level ◽  
Complete Characterization ◽  
Cell Parameters ◽  
Transient Spectroscopy ◽  
Almost All ◽  
Device Properties ◽  
Compound Materials

AbstractDeep level transient spectroscopy (DLTS) is the best technique for monitoring and characterizing deep levels introduced intentionally or occurring naturally in semiconductor materials and complete devices. DLTS has the advantage over all the techniques used to-date in that it fulfils almost all the requirements for a complete characterization of a deep centre and their correlation with the device properties. In particular the method can determine the activation energy of a deep level, its capture cross-section and concentration and can distinguish between traps and recombination centers.In this invited paper we provide an overview of the extensive R & D work that has been carrier out by the authors on the identification of the recombination and compensator centers in Si and III-V compound materials for space solar cells. In addition, we present an overview of key problems that remain in the understanding of the role of the point defects and their correlation with the solar cell parameters.

Networks, Shocks, and Systemic Risk

2016 ◽  
pp. 568-608 ◽  
Author(s):  
Daron Acemoglu ◽  
Asuman Ozdaglar ◽  
Alireza Tahbaz-Salehi
Keyword(s):  
Systemic Risk ◽  
Complete Characterization ◽  
Unified Framework ◽  
Macroeconomic Risk ◽  
Prior Literature

This chapter develops a unified framework for the study of how network interactions can function as a mechanism for propagation and amplification of microeconomic shocks. The framework nests various classes of games over networks, models of macroeconomic risk originating from microeconomic shocks, and models of financial interactions. Under the assumption that shocks are small, the authors provide a fairly complete characterization of the structure of equilibrium, clarifying the role of network interactions in translating microeconomic shocks into macroeconomic outcomes. This characterization provides a ranking of different networks in terms of their aggregate performance. It also sheds light on several seemingly contradictory results in the prior literature on the role of network linkages in fostering systemic risk.

scholarly journals Sperm Differentiation: The Role of Trafficking of Proteins

2020 ◽  
Vol 21 (10) ◽  
pp. 3702 ◽  
Author(s):  
Maria Teves ◽  
Eduardo Roldan ◽  
Diego Krapf ◽  
Jerome Strauss III ◽  
Virali Bhagat ◽  
...  
Keyword(s):  
Protein Trafficking ◽  
Morphological Changes ◽  
Chromatin Condensation ◽  
Complete Characterization ◽  
Transport Mechanisms ◽  
Spatial Processes ◽  
Nuclear Shaping ◽  
Temporal And Spatial

Sperm differentiation encompasses a complex sequence of morphological changes that takes place in the seminiferous epithelium. In this process, haploid round spermatids undergo substantial structural and functional alterations, resulting in highly polarized sperm. Hallmark changes during the differentiation process include the formation of new organelles, chromatin condensation and nuclear shaping, elimination of residual cytoplasm, and assembly of the sperm flagella. To achieve these transformations, spermatids have unique mechanisms for protein trafficking that operate in a coordinated fashion. Microtubules and filaments of actin are the main tracks used to facilitate the transport mechanisms, assisted by motor and non-motor proteins, for delivery of vesicular and non-vesicular cargos to specific sites. This review integrates recent findings regarding the role of protein trafficking in sperm differentiation. Although a complete characterization of the interactome of proteins involved in these temporal and spatial processes is not yet known, we propose a model based on the current literature as a framework for future investigations.

scholarly journals Polysome-Associated lncRNAs during Cardiomyogenesis of hESCs

2019 ◽  
Author(s):  
Isabela Tiemy Pereira ◽  
Lucia Spangenberg ◽  
Guillermo Cabrera ◽  
Bruno Dallagiovanna
Keyword(s):  
Gene Expression ◽  
Translational Regulation ◽  
Expression Patterns ◽  
Complete Characterization ◽  
Differential Association ◽  
Gene Expression Patterns ◽  
Biological Processes ◽  
Non Coding Rnas

Long non-coding RNAs (lncRNAs) have been found to be involved in many biological processes, including the regulation of cell differentiation, but a complete characterization of lncRNA is still lacking. Additionally, there is evidence that lncRNAs interact with ribosomes, raising questions about their functions in cells. Here, we used a developmentally staged protocol to induce cardiogenic commitment of hESCs and then investigated the differential association of lncRNAs with polysomes. Our results identified lncRNAs in both the ribosome-free and polysome-bound fractions during cardiogenesis and showed a very well-defined temporal lncRNA association with polysomes. Clustering of lncRNAs was performed according to the gene expression patterns during the five timepoints analyzed. In addition, differential lncRNA recruitment to polysomes was observed when comparing the differentially expressed lncRNAs in the ribosome-free and polysome-bound fractions or when calculating the polysome-bound vs ribosome-free ratio. The association of lncRNAs with polysomes could represent an additional cytoplasmic role of lncRNAs, e.g., in translational regulation of mRNA expression.

scholarly journals A large majority of awake hippocampal sharp-wave ripples feature spatial trajectories with momentum

2021 ◽  
Author(s):  
Emma L Krause ◽  
Jan Drugowitsch
Keyword(s):  
Temporal Dynamics ◽  
Probabilistic Approach ◽  
Complete Characterization ◽  
Sharp Wave ◽  
Natural Movement ◽  
Spatio Temporal ◽  
Almost All ◽  
Spatial Trajectories

During periods of rest, hippocampal place cells feature bursts of activity called sharp-wave ripples (SWRs). Heuristic approaches to their analysis have revealed that a small fraction of SWRs appear to "simulate" trajectories through the environment - called awake hippocampal replay - while the functional role of a majority of these SWRs remains unclear. Applying a novel probabilistic approach to characterize the spatio-temporal dynamics embedded in SWRs, we instead show that almost all SWRs of foraging rodents simulate such trajectories through the environment. Furthermore, these trajectories feature momentum, that is, inertia in their velocities, that mirrors the animals' natural movement. This stands in contrast to replay events during sleep which seem to follow Brownian motion without such momentum. Lastly, interpreting the replay trajectories in the context of navigational planning revealed that similar past analyses were biased by the heuristic SWR sub-selection. Overall, our approach provides a more complete characterization of the spatio-temporal dynamics within SWRs, highlights qualitative differences between sleep and awake replay, and ought to support future, more detailed, and less biased analysis of the role of awake replay in navigational planning.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

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