scholarly journals Statistics of work and orthogonality catastrophe in discrete level systems: an application to fullerene molecules and ultra-cold trapped Fermi gases

2015 ◽  
Vol 6 ◽  
pp. 755-766 ◽  
Author(s):  
Antonello Sindona ◽  
Michele Pisarra ◽  
Mario Gravina ◽  
Cristian Vacacela Gomez ◽  
Pierfrancesco Riccardi ◽  
...  
Keyword(s):  
Fullerene Molecule ◽  
Numerical Approach ◽  
Fermi Gases ◽  
Primary Role ◽  
Fundamental Physics ◽  
Work Distribution ◽  
Photoemission Data ◽  
Trapped Fermions ◽  
Work Done ◽  
Photo Ionization

The sudden introduction of a local impurity in a Fermi sea leads to an anomalous disturbance of its quantum state that represents a local quench, leaving the system out of equilibrium and giving rise to the Anderson orthogonality catastrophe. The statistics of the work done describe the energy fluctuations produced by the quench, providing an accurate and detailed insight into the fundamental physics of the process. We present here a numerical approach to the non-equilibrium work distribution, supported by applications to phenomena occurring at very diverse energy ranges. One of them is the valence electron shake-up induced by photo-ionization of a core state in a fullerene molecule. The other is the response of an ultra-cold gas of trapped fermions to an embedded two-level atom excited by a fast pulse. Working at low thermal energies, we detect the primary role played by many-particle states of the perturbed system with one or two excited fermions. We validate our approach through the comparison with some photoemission data on fullerene films and previous analytical calculations on harmonically trapped Fermi gases.

Motion Decay Simulations of a Moored Wave Energy Converter

2020 ◽  
Author(s):  
Changqing Jiang ◽  
Ould el Moctar ◽  
Thomas E. Schellin ◽  
Guilherme Moura Paredes
Keyword(s):  
Wave Energy ◽  
Stokes Equations ◽  
Numerical Approach ◽  
Offshore Structures ◽  
Primary Role ◽  
Viscous Effects ◽  
Restoring Force ◽  
System A ◽  
Cost Reductions ◽  
Catenary System

Abstract Significant cost reductions are required for marine renewable energy to become competitive. Aside from the deployment of arrays, one key area that has been identified as having potential for cost reductions is the mooring system. A challenge, therefore, is to design mooring systems which can satisfy their primary role of station keeping while being affordable and durable. This paper presents the effects of three different mooring configurations on the motion behavior of a buoy type wave energy convertor, considering nonlinear mooring-induced fluid-structure interactions, such as the associated viscous effects. To simulate motion decay, an overset mesh method that coupled a dynamic mooring model with the Navier-Stokes equations flow solver OpenFOAM was adopted. The mooring configurations comprised an all catenary system, a catenary system with buoys, and a catenary system with buoys and clump weights. The favorable agreement between the simulations and experimental measurements validated the coupled numerical approach for simulating different mooring configurations. The mooring systems influenced not only restoring force characteristics, but also total damping of the system, which demonstrated the importance of considering mooring-induced damping when investigating moored offshore structures.

Brief Communication: The Use of Various Models of Work Distribution in the Analysis of the Czech System of Evaluation of Research

2020 ◽  
Vol 47 (4) ◽  
pp. 357-363
Author(s):  
Roman Solc
Keyword(s):  
Czech Republic ◽  
Evaluation System ◽  
Research Evaluation ◽  
Original Study ◽  
The Czech Republic ◽  
Work Distribution ◽  
Research Evaluation System ◽  
Work Done ◽  
The Relationship

This article builds on our previous work, when we critically analyzed some aspects of the research evaluation system valid in the Czech Republic until 2017. This article also focuses on the evaluation of articles in journals with IF, but develops the relationship between so-called RIV-points allocated by the system and the amount of work done, using different models of work distribution. The results generally support the conclusions of the original study.

Determination of Creep Force, Moment, and Work Distribution in Rolling Contact With Slip

1989 ◽  
Vol 111 (4) ◽  
pp. 711-718 ◽  
Author(s):  
Bor-Tsuen Wang ◽  
Robert H. Fries
Keyword(s):  
Rolling Contact ◽  
Wear Model ◽  
Contact Patch ◽  
Rail Wear ◽  
Work Distribution ◽  
Force Moment ◽  
Creep Force ◽  
Rigid Body Motions ◽  
Work Done

Investigators interested in the wear of wheels and rails frequently use a wear model that postulates wear is proportional to the work done in the contact patch. Most investigators compute the work using the rigid body motions of the wheel and the total creepage at the contact patch. Such an approach gives an overall or integrated measure of the wear in the contact patch. In previous wheel/rail wear work, we have assumed the wear to be distributed parabolically across the contact patch. In order to check this assumption and to permit refinement of our wear modeling technique, we desired to know the distribution of work within the contact patch. In order to compute the work distribution within the contact patch, we must be able to compute the distributions of both the creep force and the creepage. This paper describes a method of computing lateral and longitudinal creep force and creep moment distributions within the contact patch for combined rolling and slip conditions. It also describes the computations of creep distributions within the contact patch. The work distribution is computed from the dot product of force and creepage. The method uses Kalker’s simplified theory to determine the force and creepage distributions. The actual computations are made using a modification of Kalker’s program FASTSIM. A by-product of the work is the determination of the adhesion and slip regions for arbitrary creepage conditions.

Unsteady Work Processes Within a Low Pressure Turbine Vane Passage

2013 ◽  
Author(s):  
Martin Marx ◽  
Martin Lipfert ◽  
Martin G. Rose ◽  
Stephan Staudacher ◽  
Detlef Korte
Keyword(s):  
Pressure Fluctuations ◽  
Low Pressure ◽  
Numerical Approach ◽  
Test Facility ◽  
Work Processes ◽  
Unsteady Pressure ◽  
Low Pressure Turbine ◽  
Stator Vane ◽  
Aero Engines ◽  
Work Done

A two-stage low pressure turbine is tested within the co-operation project between the Institute of Aircraft Propulsion Systems (ILA) and MTU Aero Engines GmbH. With experimental data taken in the altitude test facility this study aims to analyze the origin and effect of unsteady pressure fluctuations causing unsteady work in the second stator vane. Measurements at aerodynamic design conditions cover steady and unsteady surface pressure data on the mid span streamline position. Unsteady pressure fluctuations are identified close to the throat plane area, which are influenced by both upstream and downstream events such as wake and potential field interaction. Upstream moving static pressure waves can be identified. To support the experimental results, URANS CFD predictions of the whole turbine configuration were performed. The numerical approach is suitable to reproduce the observed phenomena and allows a deeper investigation. The observed pressure pulsations influence the local unsteady work done to and by the fluid. An evaluation of particle paths in the second stator vane indicates an isentropic energy transfer from free stream to wake fluid. Due to this unsteady energy exchange the momentum deficit of the wake gets reduced, resulting in a potential benefit on the mixing loss.

ON THE MECHANICS OF ELLIPSOIDAL FULLERENES INSIDE OPEN CARBON NANOCONES: A NOVEL NUMERICAL APPROACH

NANO ◽  
2014 ◽  
Vol 09 (03) ◽  
pp. 1450034 ◽  
Author(s):  
R. ANSARI ◽  
F. SADEGHI ◽  
M. FAGHIH SHOJAEI
Keyword(s):  
Potential Energy ◽  
Fullerene Molecule ◽  
Interaction Force ◽  
Numerical Approach ◽  
Continuum Approximation ◽  
Vertex Angle ◽  
Geometrical Parameters ◽  
Operational Matrices ◽  
Carbon Nanocones ◽  
Open Cnc

In this research, mechanics of concentric ellipsoidal fullerenes inside open carbon nanocones (CNCs) is investigated. To this end, using continuum approximation in conjunction with Lennard-Jones (LJ) potential function, quadruple-integral expressions associated with van der Waals (vdW) potential energy and interaction force are first derived. For determination of these expressions, it is assumed that the fullerene molecule enters the open CNC through the small end or wide end. Thereafter, an efficient approach based on the differential quadrature (DQ) method is proposed to numerically evaluate the obtained quadruple integrals. The proposed method takes advantage of computing multidimensional integrals efficiently with using appropriate number of grid points. By introducing DQ-based operational matrices of differentiation and integration, the quadruple-integral expressions are estimated over their domains. Moreover, new semianalytical expressions are introduced in terms of triple integrals to evaluate vdW interactions. The validity and accuracy of the introduced numerical method are proved by comparing the results obtained through this method with ones achieved via the semianalytical expressions. The ease of implementation and quick answer of the demonstrated numerical solution enable us to comprehensively examine the effects of different geometrical parameters such as small end radius wide end radius and vertex angle of nanocone on the distributions of vdW potential energy and interaction force. The results reveal that the ellipsoidal fullerene undergoes an asymmetrical motion along the axis of open CNC.

Structure of Myosin Subfragment-1 from Electron Microscopy and Crystallography

1988 ◽  
Vol 46 ◽  
pp. 156-157
Author(s):  
Donald A. Winkelmann
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Actin Filaments ◽  
Light Chains ◽  
Myosin Filament ◽  
Primary Role ◽  
Heavy Chains ◽  
Myosin Subfragment ◽  
Myosin Subfragment 1 ◽  
Globular Head

The primary role of the interaction of actin and myosin is the generation of force and motion as a direct consequence of the cyclic interaction of myosin crossbridges with actin filaments. Myosin is composed of six polypeptides: two heavy chains of molecular weight 220,000 daltons and two pairs of light chains of molecular weight 17,000-23,000. The C-terminal portions of the myosin heavy chains associate to form an α-helical coiled-coil rod which is responsible for myosin filament formation. The N-terminal portion of each heavy chain associates with two different light chains to form a globular head that binds actin and hydrolyses ATP. Myosin can be fragmented by limited proteolysis into several structural and functional domains. It has recently been demonstrated using an in vitro movement assay that the globular head domain, subfragment-1, is sufficient to cause sliding movement of actin filaments.The discovery of conditions for crystallization of the myosin subfragment-1 (S1) has led to a systematic analysis of S1 structure by x-ray crystallography and electron microscopy. Image analysis of electron micrographs of thin sections of small S1 crystals has been used to determine the structure of S1 in the crystal lattice.

Immunogold localization of calmodulin in root caps of the maize Cultivar Merit

1990 ◽  
Vol 48 (3) ◽  
pp. 674-675
Author(s):  
P.T. Nguyen ◽  
C. Uphoff ◽  
C.L. Stinemetz
Keyword(s):  
Calcium Binding ◽  
Calcium Transport ◽  
Primary Role ◽  
Immunogold Localization ◽  
Root Tips ◽  
Electrical Currents ◽  
Considerable Evidence ◽  
Maize Cultivar ◽  
Gravity Response ◽  
Induced Changes

Considerable evidence suggest that the calcium-binding protein calmodulin (CaM) may mediate calcium action and/or transport important in the gravity response of plants. Calmodulin is present in both shoots and roots and is capable of regulating calcium transport in plant vesicles. In roots calmodulin is concentrated in the tip, the gravisensing region of the root; and is reported to be closely associated with amyloplasts, organelles suggested to play a primary role in gravi-perception. Inhibitors of CaM such as chlorpromazine, calmidazolium, and compound 48/80 interfere with the gravitropic response of both snoots and roots. The magnitude of the inhibition corresponded well with the extent to which the drug binds to endogenous CaM. Compound 48/80 and calmidazolium block gravi-induced changes in electrical currents across root tips, a phenomenon thought to be associated with the sensing of the gravity stimulus.In this study, we have investigated the subcellular distribution of CaM in graviresponsive and non-graviresponsive root caps of the maize cultivar Merit.

The Psychosocial Aspects of Feeding in the Neonatal Intensive Care Unit and Beyond

2019 ◽  
Vol 4 (6) ◽  
pp. 1507-1515
Author(s):  
Lauren L. Madhoun ◽  
Robert Dempster
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Neonatal Intensive Care Unit ◽  
Hospital Discharge ◽  
Neonatal Intensive Care ◽  
Oral Feeding ◽  
Medical Attention ◽  
Primary Role ◽  
Speech Language Pathologists ◽  
The Family

Purpose Feeding challenges are common for infants in the neonatal intensive care unit (NICU). While sufficient oral feeding is typically a goal during NICU admission, this can be a long and complicated process for both the infant and the family. Many of the stressors related to feeding persist long after hospital discharge, which results in the parents taking the primary role of navigating the infant's course to ensure continued feeding success. This is in addition to dealing with the psychological impact of having a child requiring increased medical attention and the need to continue to fulfill the demands at home. In this clinical focus article, we examine 3 main areas that impact psychosocial stress among parents with infants in the NICU and following discharge: parenting, feeding, and supports. Implications for speech-language pathologists working with these infants and their families are discussed. A case example is also included to describe the treatment course of an infant and her parents in the NICU and after graduation to demonstrate these points further. Conclusion Speech-language pathologists working with infants in the NICU and following hospital discharge must realize the family context and psychosocial considerations that impact feeding progression. Understanding these factors may improve parental engagement to more effectively tailor treatment approaches to meet the needs of the child and family.

Social Cognition in Gilles de la Tourette Syndrome

2019 ◽  
Vol 30 (4) ◽  
pp. 243-249
Author(s):  
Ronja Weiblen ◽  
Melanie Jonas ◽  
Sören Krach ◽  
Ulrike M. Krämer
Keyword(s):  
Tourette Syndrome ◽  
Social Cognitive ◽  
Mirror Neuron System ◽  
Mirror Neuron ◽  
Theoretical Work ◽  
Neural Processes ◽  
The Social ◽  
Decision Making System ◽  
Social Decision Making ◽  
Work Done

Abstract. Research on the neural mechanisms underlying Gilles de la Tourette syndrome (GTS) has mostly concentrated on abnormalities in basal ganglia circuits. Recent alternative accounts, however, focused more on social and affective aspects. Individuals with GTS show peculiarities in their social and affective domain, including echophenomena, coprolalia, and nonobscene socially inappropriate behavior. This article reviews the experimental and theoretical work done on the social symptoms of GTS. We discuss the role of different social cognitive and affective functions and associated brain networks, namely, the social-decision-making system, theory-of-mind functions, and the so-called “mirror-neuron” system. Although GTS affects social interactions in many ways, and although the syndrome includes aberrant social behavior, the underlying cognitive, affective, and neural processes remain to be investigated.

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