Experiments and Numerical Simulations of Electrodynamic Tether
Iki, Kentaro; Kawamoto, Satomi; Takahashi, Ayaka; Ishimoto, Tomori; Yanagida, Atsushi; Toda, Susumu
As an effective means of suppressing space debris growth, the Aerospace Research and Development Directorate of the Japan Aerospace Exploration Agency (JAXA) has been investigating an active space debris removal system that employs highly efficient electrodynamic tether (EDT) technology for orbital transfer. This study investigates tether deployment dynamics by means of on-ground experiments and numerical simulations of an electrodynamic tether system. Some key parameters used in the numerical simulations, such as the elastic modulus and damping ratio of the tether, the spring constant of the coiling of the tether, and deployment friction, must be estimated, and various experiments are conducted to determine these values. As a result, the following values were obtained: The elastic modulus of the tether was 40 GPa, and the damping ratio of the tether was 0.02. The spring constant and the damping ratio of the tether coiling were 10-4 N/m and 0.025 respectively. The deployment friction was 0.038ν + 0.005 N. In numerical simulations using a multiple mass tether model, tethers with lengths of several kilometers are deployed and the attitude dynamics of satellites attached to the end of the tether and tether libration are calculated. As a result, the simulations confirmed successful deployment of the tether with a length of 500 m using the electrodynamic tether system.
The PROPEL Electrodynamic Tether Demonstration Mission
Bilen, Sven G.; Johnson, C. Les; Wiegmann, Bruce M.; Alexander, Leslie; Gilchrist, Brian E.; Hoyt, Robert P.; Elder, Craig H.; Fuhrhop, Keith P.; Scadera, Michael
2012-01-01
The PROPEL ("Propulsion using Electrodynamics") mission will demonstrate the operation of an electrodynamic tether propulsion system in low Earth orbit and advance its technology readiness level for multiple applications. The PROPEL mission has two primary objectives: first, to demonstrate the capability of electrodynamic tether technology to provide robust and safe, near-propellantless propulsion for orbit-raising, de-orbit, plane change, and station keeping, as well as to perform orbital power harvesting and formation flight; and, second, to fully characterize and validate the performance of an integrated electrodynamic tether propulsion system, qualifying it for infusion into future multiple satellite platforms and missions with minimal modification. This paper provides an overview of the PROPEL system and design reference missions; mission goals and required measurements; and ongoing PROPEL mission design efforts.
Passivity-Based Control of a Rigid Electrodynamic Tether
DEFF Research Database (Denmark)
Larsen, Martin Birkelund; Blanke, Mogens
2011-01-01
Electrodynamic tethers provide actuation for performing orbit correction of spacecrafts. When an electrodynamic tether system is orbiting the Earth in an inclined orbit, periodic changes in the magnetic field result in a family of unstable periodic solutions in the attitude motion. This paper shows...... how these periodic solutions can be stabilized by controlling only the current through the tether. A port-controlled Hamiltonian formulation is employed to describe the tethered satellite system and a passive input-output connection is utilized in the control design. The control law consists of two...
Lyapunov Orbits in the Jupiter System Using Electrodynamic Tethers
Bokelmann, Kevin; Russell, Ryan P.; Lantoine, Gregory
2013-01-01
Various researchers have proposed the use of electrodynamic tethers for power generation and capture from interplanetary transfers. The effect of tether forces on periodic orbits in Jupiter-satellite systems are investigated. A perturbation force is added to the restricted three-body problem model and a series of simplifications allows development of a conservative system that retains the Jacobi integral. Expressions are developed to find modified locations of equilibrium positions. Modified families of Lyapunov orbits are generated as functions of tether size and Jacobi integral. Zero velocity curves and stability analyses are used to evaluate the dynamical properties of tether-modified orbits.
Implementation Options for the PROPEL Electrodynamic Tether Demonstration Mission
Bilen, Sven G.; Johnson, C. Les; Gilchrist, Brian E.; Hoyt, Robert P.; Elder, Craig H.; Fuhrhop, Keith P.; Scadera, Michael; Stone, Nobie
2014-01-01
The PROPEL ("Propulsion using Electrodynamics") flight demonstration mission concept will demonstrate the use of an electrodynamic tether (EDT) for generating thrust, which will allow the propulsion system to overcome the limitations of the rocket equation. The mission concept has been developed by a team of government, industry, and academia partners led by NASA Marshall Space Flight Center (MSFC). PROPEL is being designed for versatility of the EDT system with multiple end users in mind and to be flexible with respect to platform. Previously, we reported on a comprehensive mission design for PROPEL with a mission duration of six months or longer with multiple mission goals including demonstration of significant boost, deboost, inclination change, and drag make-up activities. To explore a range of possible configurations, primarily driven by cost considerations, other mission concept designs have been pursued. In partnership with the NASA's Office of Chief Technologist (OCT) Game Changing Program, NASA MSFC Leadership, and the MSFC Advanced Concepts Office, a mission concept design was developed for a near-term EDT propulsion flight validation mission. The Electrodynamic Tether Propulsion Study (ETPS) defined an EDT propulsion system capable of very large delta-V for use on future missions developed by NASA, DoD, and commercial customers. To demonstrate the feasibility of an ETPS, the study focused on a space demonstration mission concept design with configuration of a pair of tethered satellite busses, one of which is the Japanese H-II Transfer Vehicle (HTV). The HTV would fly its standard ISS resupply mission. When resupply mission is complete, the ISS reconfigures and releases the HTV to perform the EDT experiment at safe orbital altitudes below the ISS. Though the focus of this particular mission concept design addresses a scenario involving the HTV or a similar vehicle, the propulsion system's capability is relevant to a number of applications, as noted above
Modeling and Control of Electrodynamic Tethers - an Energy and Topology Approach
DEFF Research Database (Denmark)
Larsen, Martin Birkelund
A space tether is a cable used to connect spacecrafts in an orbiting structure. If an electrical current is lead through the tether, it can be utilized to provide propulsion for the spacecraft. In this case the cable is referred to as an electrodynamic tether. The system utilizes the magnetic field...... of the Earth for creating a Lorentz force along the tether which occur when a current carrying wire operates in a magnetic field. The use of electrodynamic tethers are interesting since they operate solely on electrical energy, which can be provided by solar panels of the spacecrafts. In this way the amount...... when using electrodynamic tethers is that the force created along the tether is based on an external uncontrollable condition, namely the magnetic field. Even whit a known model of the magnetic field, limitations to the creation of the Lorentz force still exists, since the force can only be generated...
Electron Emitter for small-size Electrodynamic Space Tether using MEMS Technology
DEFF Research Database (Denmark)
Fleron, René A. W.; Blanke, Mogens
2004-01-01
Adjustment of the orbit of a spacecraft using the forces created by an electro-dynamic space-tether has been shown as a theoretic possibility in recent literature. Practical implementation is being pursued for larger scale missions where a hot filament device controls electron emission...... and the current flowing in the electrodynamic space tether. Applications to small spacecraft, or space debris in the 1–10 kg range, possess difficulties with electron emission technology, as low power emitting devices are needed. This paper addresses the system concepts of a small spacecraft electrodynamic tether...... system with focus on electron emitter design and manufacture using micro-electro-mechanical- system (MEMS) technology. The paper addresses the system concepts of a small size electrodynamic tether mission and shows a novel electron emitter for the 1-2 mA range where altitude can be effectively affected...
Investigation of electrodynamic stabilization and control of long orbiting tethers
Colombo, G.; Arnold, D.
1984-01-01
The state-of-the-art in tether modelling among participants in the Tethered Satellite System (TSS) Program, the slack tether and its behavior, and certain advanced applications of the tether to problems in orbital mechanics are identified. The features and applications of the TSS software set are reviewed. Modelling the slack tether analytically with as many as 50 mass points and the application of this new model to a study of the behavior of a broken tether near the Shuttle are described. A reel control algorithm developed by SAO and examples of its use are described, including an example which also demonstrates the use of the tether in transferring a heavy payload from a low-orbiting Shuttle to a high circular orbit. Capture of a low-orbiting payload by a Space Station in high circular orbit is described. Energy transfer within a dumbbell-type spacecraft by cyclical reeling operations or gravitational effects on the natural elasticity of the connecting tether, it is shown, can circularize the orbit of the spacecraft.
Adams, Mitzi; HabashKrause, Linda
2012-01-01
Recent interest in using electrodynamic tethers (EDTs) for orbital maneuvering in Low Earth Orbit (LEO) has prompted the development of the Marshall ElectroDynamic Tether Orbit Propagator (MEDTOP) model. The model is comprised of several modules which address various aspects of EDT propulsion, including calculation of state vectors using a standard orbit propagator (e.g., J2), an atmospheric drag model, realistic ionospheric and magnetic field models, space weather effects, and tether librations. The natural electromotive force (EMF) attained during a radially-aligned conductive tether results in electrons flowing down the tether and accumulating on the lower-altitude spacecraft. The energy that drives this EMF is sourced from the orbital energy of the system; thus, EDTs are often proposed as de-orbiting systems. However, when the current is reversed using satellite charged particle sources, then propulsion is possible. One of the most difficult challenges of the modeling effort is to ascertain the equivalent circuit between the spacecraft and the ionospheric plasma. The present study investigates the use of the NASA Charging Analyzer Program (NASCAP) to calculate currents to and from the tethered satellites and the ionospheric plasma. NASCAP is a sophisticated set of computational tools to model the surface charging of three-dimensional (3D) spacecraft surfaces in a time-varying space environment. The model's surface is tessellated into a collection of facets, and NASCAP calculates currents and potentials for each one. Additionally, NASCAP provides for the construction of one or more nested grids to calculate space potential and time-varying electric fields. This provides for the capability to track individual particles orbits, to model charged particle wakes, and to incorporate external charged particle sources. With this study, we have developed a model of calculating currents incident onto an electrodynamic tethered satellite system, and first results are shown
Advanced Electrodynamic Tether Systems: Modeling of Scattering and Unsteady Effects
2008-06-06
spacecraft and satellites. A high altitude nuclear detonation would likely create a new high energy electron belt and increase the radiation risk to...our tether has no reason to roll, making O=0, and thus cosO =1. The y-component of the torque is thus expressed: < = < =< = FF cossin3 222 ’ (S...ions from the integral limits to manageable levels. Our goal is to isolate the permutations of initial velocities and impact parameters such that
Estes, Robert D.
1989-01-01
A method is presented for calculating the electromagnetic wave field on the earth's surface associated with the operation of an electrodynamic tethered satellite system of constant or slowly varying current in the upper ionosphere. The wave field at the ionospheric boundary and on the earth's surface is obtained by numerical integration. The results suggest that the ionospheric waves do not propagate into the atmosphere and that the image of the Alfven wings from a steady-current tether should be greatly broadened on the earth's surface.
Electrodynamic Tethers and E-Sails as Active Experiment Testbeds and Technologies in Space
Gilchrist, B. E.; Wiegmann, B.; Johnson, L.; Bilen, S. G.; Habash Krause, L.; Miars, G.; Leon, O.
2017-12-01
The use of small-to-large flexible structures in space such as tethers continues to be studied for scientific and technology applications. Here we will consider tether electrodynamic and electrostatic interactions with magneto-plasmas in ionospheres, magnetospheres, and interplanetary space. These systems are enabling fundamental studies of basic plasma physics phenomena, allowing direct studies of the space environment, and generating technological applications beneficial for science missions. Electrodynamic tethers can drive current through the tether based on the Lorenz force adding or extracting energy from its orbit allowing for the study of charged bodies or plasma plumes moving through meso-sonic magnetoplasmas [1]. Technologically, this also generates propulsive forces requiring no propellant and little or no consumables in any planetary system with a magnetic field and ionosphere, e.g., Jupiter [2]. Further, so called electric sails (E-sails) are being studied to provide thrust through momentum exchange with the hypersonic solar wind. The E-sail uses multiple, very long (10s of km) charged, mostly bare rotating conducting tethers to deflect solar wind protons. It is estimated that a spacecraft could achieve a velocity over 100 km/s with time [3,4]. 1. Banks, P.M., "Review of electrodynamic tethers for space plasma science," J. Spacecraft and Rockets, vol. 26, no. 4, pp. 234-239, 1989. 2. Talley, C., J. Moore, D. Gallagher, and L. Johnson, "Propulsion and power from a rotating electrodynamic tether at Jupiter," 38th AIAA Aerospace Sciences Meeting and Exhibit, January 2000. 3. Janhunen, P., "The electric sail—A new propulsion method which may enable fast missions to the outer solar system," J. British Interpl. Soc., vol. 61, no. 8, pp. 322-325, 2008. 4. Wiegman, B., T. Scheider, A. Heaton, J. Vaughn, N. Stone, and K. Wright, "The Heliopause Electrostatic Rapid Transit System (HERTS)—Design, trades, and analyses performed in a two-year NASA investigation
Control by damping Injection of Electrodynamic Tether System in an Inclined Orbit
DEFF Research Database (Denmark)
Larsen, Martin Birkelund; Blanke, Mogens
2009-01-01
dynamical system. Based on this model, a nonlinear controller is designed that will make the system asymptotically stable around its open-loop equilibrium. The control scheme handles the time-varying nature of the system in a suitable manner resulting in a large operational region. The performance...... of the closed loop system is treated using Floquet theory, investigating the closed loop properties for their dependency of the controller gain and orbit inclination.......Control of a satellite system with an electrodynamic tether as actuator is a time-periodic and underactuated control problem. This paper considers the tethered satellite in a Hamiltonian framework and determines a port-controlled Hamiltonian formulation that adequately describes the nonlinear...
Arnold, D. A.; Dobrowolny, M.
1981-01-01
An algorithm for using electric currents to control pendular oscillations induced by various perturbing forces on the Skyhook wire is considered. Transverse and vertical forces on the tether; tether instability modes and causes during retrieval by space shuttle; simple and spherical pendulum motion and vector damping; and current generation and control are discussed. A computer program for numerical integration of the in-plane and out-of-plane displacements of the tether vs time was developed for heuristic study. Some techniques for controlling instabilities during payload retrieval and methods for employing the tether for launching satellites from the space shuttle are considered. Derivations and analyses of a general nature used in all of the areas studied are included.
Nonlinear model of short-scale electrodynamics in the auroral ionosphere
Directory of Open Access Journals (Sweden)
J.-M. A. Noël
Full Text Available The optical detection of auroral subarcs a few tens of m wide as well as the direct observation of shears several m/s per m over km to sub km scales by rocket instrumentation both indicate that violent and highly localized electrodynamics can occur at times in the auroral ionosphere over scales 100 m or less in width. These observations as well as the detection of unstable ion-acoustic waves observed by incoherent radars along the geomagnetic field lines has motivated us to develop a detailed time-dependent two-dimensional model of short-scale auroral electrodynamics that uses current continuity, Ohm's law, and 8-moment transport equations for the ions and electrons in the presence of large ambient electric fields to describe wide auroral arcs with sharp edges in response to sharp cut-offs in precipitation (even though it may be possible to describe thin arcs and ultra-thin arcs with our model, we have left such a study for future work. We present the essential elements of this new model and illustrate the model's usefulness with a sample run for which the ambient electric field is 100 mV/m away from the arc and for which electron precipitation cuts off over a region 100 m wide. The sample run demonstrates that parallel current densities of the order of several hundred µA m^{-2} can be triggered in these circumstances, together with shears several m/s per m in magnitude and parallel electric fields of the order of 0.1 mV/m around 130 km altitude. It also illustrates that the local ionospheric properties like densities, temperature and composition can strongly be affected by the violent localized electrodynamics and vice-versa.
Key words: Ionosphere (auroral ionosphere, electric fields and currents, ionosphere-magnetosphere interactions
Stabilized platform for tethered balloon soundings of broadband long- and short-wave radiation
International Nuclear Information System (INIS)
Alzheimer, J.M.; Anderson, G.A.; Whiteman, C.D.
1993-01-01
Changes in the composition of trace gases in the earth's atmosphere have been reported by many observers, and a general concern has been expressed regarding possible changes to the earth's climate that may be caused by radiatively active gases introduced into the earth's atmosphere by man's activities. Radiatively active trace gases produce temperature changes in the earth's atmosphere through changes in radiative flux divergence. Our knowledge of and means of measuring radiative flux divergence is very limited. A few observations of vertical radiative flux divergences have been reported from aircraft from radiometersondes from towers and from large tethered balloons. These measurement techniques suffers from one or more drawbacks, including shallow sounding depths (towers), high cost (aircraft), complicated logistics (large tethered balloons), and limitation to nighttime hours (radiometersondes). Changes in radiative flux divergence caused by anthropogenic trace gases are expected to be quite small, and will be difficult to measure with existing broadband radiative flux instruments. The emphasis of present research in global climate change is thus being focused on improving radiative transfer algorithms in global climate models. The radiative parameterizations in these models are at an early stage of development and information is needed regarding their performance, especially in cloudy conditions. The impetus for the research reported in this paper is the need for a device that can supplement existing means of measuring vertical profiles of long- and short-wave irradiance and radiative flux divergence. We have designed a small tethered-balloon-based system that can make radiometric soundings through the atmospheric boundary layer. This paper discusses the concept, the design considerations, and the design and construction of this sounding system. The performance of the system will be tested in a series of balloon flights scheduled for the fall and winter of 1992
Stone, Noble H.
2007-01-01
The Tethered Satellite System Space Shuttle missions, TSS-1 in 1993 and TSS-1R in 1996, were the height of space tether technology development. Since NASA's investment of some $200M and two Shuttle missions in those two pioneering missions, there have been several smaller tether flight experiments, but interest in this promising technology has waned within NASA as well as the DOD agencies. This is curious in view of the unique capabilities of space tether systems and the fact that they have been flight validated and shown to perform as, or better than, expected in earth orbit. While it is true that the TSS-1, TSS-1R and SEDS-2 missions experienced technical difficulties, the causes of these early developmental problems are now known to be design or materials flaws that are (1) unrelated to the basic viability of space tether technology, and (2) they are readily corrected. The purpose of this paper is to review the dynamic and electrodynamic fundamentals of space tethers and the unique capabilities they afford (that are enabling to certain types of space missions); to elucidate the nature, cause, and solution of the early developmental problems; and to provide an update on progress made in development of the technology. Finally, it is shown that (1) all problems experienced during early development of the technology now have solutions; and (2) the technology has been matured by advances made in strength and robustness of tether materials, high voltage engineering in the space environment, tether health and status monitoring, and the elimination of the broken tether hazard. In view of this, it is inexplicable why this flight-validated technology has not been utilized in the past decade, considering the powerful and unique capabilities that space tethers can afford that are, not only required to carryout, otherwise, unobtainable missions, but can also greatly reduce the cost of certain on-going space operations.
Space Environmental Effects on Coated Tether Materials
Gittemeier, Keith A.; Hawk, Clark W.; Finckenor, Miria M.; Watts, Ed
2005-01-01
The University of Alabama in Huntsville s Propulsion Research Center has teamed with NASA's Marshall Space Flight Center (MSFC) to research the effects of atomic oxygen (AO) bombardment on coated tether materials. Tethers Unlimited Inc. has provided several candidate tether materials with various coatings for AO exposure in MSFC s Atomic Oxygen Beam Facility. Additional samples were exposed to ultraviolet (UV) radiation at MSFC. AO erodes most organic materials, and ultraviolet radiation embrittles polymers. This test series was performed to determine the effect of AO and UV on the mechanical integrity of tether materials that were treated with AO-protective coatings, such as polyhedral oligomeric silsesquioxane (POSS) or metallization. Both TUI's Multi-Application Survivable Tether (MAST) Experiment and Marshall Space Flight Center s Momentum Exchange Electrodynamic Reboost (MXER) programs will benefit from this research by helping to determine tether materials and coatings that give the longest life with the lowest mass penalty.
International Nuclear Information System (INIS)
Akhiezer, A.I.
1983-01-01
Basic ideas of quantum electrodynamics history of its origination and its importance are outlined. It is shown low the notion of the field for each kind of particles and the notion of vacuum for such field had originated and been affirmed how a new language of the Feynman diagrams had appeared without which it is quite impossible to described complex processes of particle scattering and mutual transformation. The main problem of the quantum electrodynamics is to find a scattering matrix, which solution comes to the determination of the Green electrodynamic functions. A review is given of papers on clarifying the asymptotic behaviour of the Green electrodynamic functions in the range of high pulses, on studying the Compton effect, bremsstrahlung irradiation Raman light scattering elastic scattering during channeling of charged particles in a crystal
International Nuclear Information System (INIS)
Volland, H.
1984-01-01
The book Atmospheric Electrodynamics, by Hans Voland is reviewed. The book describes a wide variety of electrical phenomena occurring in the upper and lower atmosphere and develops the mathematical models which simulate these processes. The reviewer finds that the book is of interest to researchers with a background in electromagnetic theory but is of only limited use as a reference work
Greiner, Walter
2009-01-01
This textbook on Quantum Electrodynamics is a thorough introductory text providing all necessary mathematical tools together with many examples and worked problems. In their presentation of the subject the authors adopt a heuristic approach based on the propagator formalism. The latter is introduced in the first two chapters in both its nonrelativistic and relativistic versions. Subsequently, a large number of scattering and radiation processes involving electrons, positrons, and photons are introduced and their theoretical treatment is presented in great detail. Higher order processes and renormalization are also included. The book concludes with a discussion of two-particle states and the interaction of spinless bosons. This completely revised and corrected new edition provides several additions to enable deeper insight in formalism and application of quantum electrodynamics.
Zangwill, Andrew
2013-01-01
An engaging writing style and a strong focus on the physics make this comprehensive, graduate-level textbook unique among existing classical electromagnetism textbooks. Charged particles in vacuum and the electrodynamics of continuous media are given equal attention in discussions of electrostatics, magnetostatics, quasistatics, conservation laws, wave propagation, radiation, scattering, special relativity and field theory. Extensive use of qualitative arguments similar to those used by working physicists makes Modern Electrodynamics a must-have for every student of this subject. In 24 chapters, the textbook covers many more topics than can be presented in a typical two-semester course, making it easy for instructors to tailor courses to their specific needs. Close to 120 worked examples and 80 applications boxes help the reader build physical intuition and develop technical skill. Nearly 600 end-of-chapter homework problems encourage students to engage actively with the material. A solutions manual is availa...
1990-01-01
Quantum electrodynamics is an essential building block and an integral part of the gauge theory of unified electromagnetic, weak, and strong interactions, the so-called standard model. Its failure or breakdown at some level would have a most profound impact on the theoretical foundations of elementary particle physics as a whole. Thus the validity of QED has been the subject of intense experimental tests over more than 40 years of its history. This volume presents an up-to-date review of high precision experimental tests of QED together with comprehensive discussion of required theoretical wor
Materials for advancement of MXER tether design (1000-371), Phase I
National Aeronautics and Space Administration — There exist a need to develop, identify, and classify various materials that can be used in the fabrication of electrodynamic tethers for various applications. These...
UV-Curable Hybrid Nanocomposite Coating to Protect Tether Polymer Materials, Phase I
National Aeronautics and Space Administration — To address the NASA need for coatings to protect and strengthen tether materials for Momentum-exchange Electrodynamic Reboost (MXER) technology, Luminit, LLC,...
Analytical investigation of the dynamics of tethered constellations in Earth orbit, phase 2
Lorenzini, Enrico C.; Gullahorn, Gordon E.; Cosmo, Mario L.; Estes, Robert D.; Grossi, Mario D.
1994-01-01
This final report covers nine years of research on future tether applications and on the actual flights of the Small Expendable Deployment System (SEDS). Topics covered include: (1) a description of numerical codes used to simulate the orbital and attitude dynamics of tethered systems during station keeping and deployment maneuvers; (2) a comparison of various tethered system simulators; (3) dynamics analysis, conceptual design, potential applications and propagation of disturbances and isolation from noise of a variable gravity/microgravity laboratory tethered to the Space Station; (4) stability of a tethered space centrifuge; (5) various proposed two-dimensional tethered structures for low Earth orbit for use as planar array antennas; (6) tethered high gain antennas; (7) numerical calculation of the electromagnetic wave field on the Earth's surface on an electrodynamically tethered satellite; (8) reentry of tethered capsules; (9) deployment dynamics of SEDS-1; (10) analysis of SEDS-1 flight data; and (11) dynamics and control of SEDS-2.
Tether dynamics and control results for tethered satellite system's initial flight
Chapel, Jim D.; Flanders, Howard
The recent Tethered Satellite System-1 (TSS-1) mission has provided a wealth of data concerning the dynamics of tethered systems in space and has demonstrated the effectiveness of operational techniques designed to control these dynamics. In this paper, we review control techniques developed for managing tether dynamics, and discuss the results of using these techniques for the Tethered Satellite System's maiden flight on STS-46. In particular, the flight results of controlling libration dynamics, string dynamics, and slack tether are presented. These results show that tether dynamics can be safely managed. The overall stability of the system was found to be surprisingly good even at relatively short tether lengths. In fact, the system operated in passive mode at a tether length of 256 meters for over 9 hours. Only monitoring of the system was required during this time. Although flight anomalies prevented the planned deployment to 20 km, the extended operations at shorter tether lengths have proven the viability of using tethers in space. These results should prove invaluable in preparing for future missions with tethered objects in space.
Impact of quantum electrodynamics
International Nuclear Information System (INIS)
Brodsky, S.J.
1975-12-01
A review is given of recent developments in quantum electrodynamics, particularly those involving tests of muon dynamics as well as quantum electrodynamics tests. A new limit on possible muon composite structure is also given. The impact of quantum electrodynamics and its generalizations, the gauge theories, to other areas of physics, including the weak and strong interactions and the atomic spectrum of new particles. The consequences of scale invariance in hadron, atomic, and nuclear physics are reviewed. 119 references
Vierling, L.A.; Fersdahl, M.; Chen, X.; Li, Z.; Zimmerman, P.
2006-01-01
We describe a new remote sensing system called the Short Wave Aerostat-Mounted Imager (SWAMI). The SWAMI is designed to acquire co-located video imagery and hyperspectral data to study basic remote sensing questions and to link landscape level trace gas fluxes with spatially and temporally appropriate spectral observations. The SWAMI can fly at altitudes up to 2 km above ground level to bridge the spatial gap between radiometric measurements collected near the surface and those acquired by other aircraft or satellites. The SWAMI platform consists of a dual channel hyperspectral spectroradiometer, video camera, GPS, thermal infrared sensor, and several meteorological and control sensors. All SWAMI functions (e.g. data acquisition and sensor pointing) can be controlled from the ground via wireless transmission. Sample data from the sampling platform are presented, along with several potential scientific applications of SWAMI data.
Introduction to Electrodynamics
Griffiths, David J.
2017-06-01
1. Vector analysis; 2. Electrostatics; 3. Potentials; 4. Electric fields in matter; 5. Magnetostatics; 6. Magnetic fields in matter; 7. Electrodynamics; 8. Conservation laws; 9. Electromagnetic waves; 10. Potentials and fields; 11. Radiation; 12. Electrodynamics and relativity; Appendix A. Vector calculus in curvilinear coordinates; Appendix B. The Helmholtz theorem; Appendix C. Units; Index.
Kumar, Vinay
2016-01-01
The present book entitled Concepts of Electrodynamics meets the demand of students of all engineering, graduate, honours and postgraduate courses in a single volume. This book covers all the topics on electrodynamics as per the new syllabus prescribed by UGC and AICTE and we do hope that this book will revive interest in the study of various topics on electrodynamics which will carries the reader to a high level of understanding. The text is enriched with a large number of solved examples apart from appropriate illustrations and examples in each chapter.
Tethering sockets and wrenches
Johnson, E. P.
1990-01-01
The tethering of sockets and wrenches was accomplished to improve the safety of working over motor segments. To accomplish the tethering of the sockets to the ratchets, a special design was implemented in which a groove was machined into each socket. Each socket was then fitted with a snap ring that can spin around the machined groove. The snap ring is tethered to the handle of the ratchet. All open end wrenches are also tethered to the ratchet or to the operator, depending upon the type. Tests were run to ensure that the modified tools meet torque requirements. The design was subsequently approved by Space Safety.
Tethering sockets and wrenches
Johnson, E. P.
1990-07-01
The tethering of sockets and wrenches was accomplished to improve the safety of working over motor segments. To accomplish the tethering of the sockets to the ratchets, a special design was implemented in which a groove was machined into each socket. Each socket was then fitted with a snap ring that can spin around the machined groove. The snap ring is tethered to the handle of the ratchet. All open end wrenches are also tethered to the ratchet or to the operator, depending upon the type. Tests were run to ensure that the modified tools meet torque requirements. The design was subsequently approved by Space Safety.
Foundations of electrodynamics
Moon, Parry
2013-01-01
Advanced undergraduate text presupposes some knowledge of electricity and magnetism, making substantial use of vector analysis. A serious development of electrodynamics on a postulational basis that clearly defines each concept. 1960 edition.
Propagator of stochastic electrodynamics
International Nuclear Information System (INIS)
Cavalleri, G.
1981-01-01
The ''elementary propagator'' for the position of a free charged particle subject to the zero-point electromagnetic field with Lorentz-invariant spectral density proportionalω 3 is obtained. The nonstationary process for the position is solved by the stationary process for the acceleration. The dispersion of the position elementary propagator is compared with that of quantum electrodynamics. Finally, the evolution of the probability density is obtained starting from an initial distribution confined in a small volume and with a Gaussian distribution in the velocities. The resulting probability density for the position turns out to be equal, to within radiative corrections, to psipsi* where psi is the Kennard wave packet. If the radiative corrections are retained, the present result is new since the corresponding expression in quantum electrodynamics has not yet been found. Besides preceding quantum electrodynamics for this problem, no renormalization is required in stochastic electrodynamics
Quantum electrodynamics of strong fields
International Nuclear Information System (INIS)
Greiner, W.
1983-01-01
Quantum Electrodynamics of Strong Fields provides a broad survey of the theoretical and experimental work accomplished, presenting papers by a group of international researchers who have made significant contributions to this developing area. Exploring the quantum theory of strong fields, the volume focuses on the phase transition to a charged vacuum in strong electric fields. The contributors also discuss such related topics as QED at short distances, precision tests of QED, nonperturbative QCD and confinement, pion condensation, and strong gravitational fields In addition, the volume features a historical paper on the roots of quantum field theory in the history of quantum physics by noted researcher Friedrich Hund
Orbital Propagation of Momentum Exchange Tether Systems
Westerhoff, John
2002-01-01
An advanced concept in in-space transportation currently being studied is the Momentum-Exchange/Electrodynamic Reboost Tether System (MXER). The system acts as a large momentum wheel, imparting a Av to a payload in low earth orbit (LEO) at the expense of its own orbital energy. After throwing a payload, the system reboosts itself using an electrodynamic tether to push against Earth's magnetic field and brings itself back up to an operational orbit to prepare for the next payload. The ability to reboost itself allows for continued reuse of the system without the expenditure of propellants. Considering the cost of lifting propellant from the ,ground to LEO to do the same Av boost at $10000 per pound, the system cuts the launch cost of the payload dramatically, and subsequently, the MXER system pays for itself after a small number of missions.1 One of the technical hurdles to be overcome with the MXER concept is the rendezvous maneuver. The rendezvous window for the capture of the payload is on the order of a few seconds, as opposed to traditional docking maneuvers, which can take as long ets necessary to complete a precise docking. The payload, therefore, must be able to match its orbit to meet up with the capture device on the end of the tether at a specific time and location in the future. In order to be able to determine that location, the MXER system must be numerically propagated forward in time to predict where the capture device will be at that instant. It should be kept in mind that the propagation computation must be done faster than real-time. This study focuses on the efforts to find and/or build the tools necessary to numerically propagate the motion of the MXER system as accurately as possible.
Youngbluth, Otto; Owens, Thomas L.; Storey, Richard W.
1990-01-01
Systems take meteorological measurements for variety of research projects. Report describes work done by NASA Langley Research Center in atmospheric research using tethered balloon systems composed of commercially available equipment. Two separate tethered balloon systems described in report have payloads and configurations tailored to requirements of specific projects. Each system capable of measuring atmospheric parameter or species in situ and then telemetering this data in real time to ground station. Meteorological data and concentration of ozone typically measured. Indicates instrumented tethered balloon systems have distinct advantages over other systems for gathering data on troposphere.
Molecular quantum electrodynamics
Craig, D P
1998-01-01
This systematic introduction to quantum electrodynamics focuses on the interaction of radiation with outer electrons and nuclei of atoms and molecules, answering the long-standing need of chemists and physicists for a comprehensive text on this highly specialized subject.Geared toward postgraduate students in the chemical sciences who require an understanding of quantum electrodynamics as applied to the interpretation of optical experiments on atoms and molecules, the text offers a detailed explanation of the quantum theory of electromagnetic radiation and its interaction with matter. It feat
Electrodynamic thermogravimetric analyzer
International Nuclear Information System (INIS)
Spjut, R.E.; Bar-Ziv, E.; Sarofim, A.F.; Longwell, J.P.
1986-01-01
The design and operation of a new device for studying single-aerosol-particle kinetics at elevated temperatures, the electrodynamic thermogravimetric analyzer (EDTGA), was examined theoretically and experimentally. The completed device consists of an electrodynamic balance modified to permit particle heating by a CO 2 laser, temperature measurement by a three-color infrared-pyrometry system, and continuous weighing by a position-control system. In this paper, the position-control, particle-weight-measurement, heating, and temperature-measurement systems are described and their limitations examined
Carroll, Joseph A.; Alexander, Charles M.
1993-01-01
Design concept promises speed, control, and reliability. Scheme for deploying tether provides for fast, free, and snagless payout and fast, dependable braking. Developed for small, expendable tethers in outer space, scheme also useful in laying transoceanic cables, deploying guidance wires to torpedoes and missiles, paying out rescue lines from ship to ship via rockets, deploying antenna wires, releasing communication and power cables to sonobuoys and expendable bathythermographs, and in reeling out lines from fishing rods.
Limits of electrodynamics: paraphotons
International Nuclear Information System (INIS)
Okun, L.B.
1982-01-01
The paper discusses the accuracy with which electromagnetic interaction is studied at large distances. Possible deviations from standard electrodynamics are investigated. The consideration is carried out the framework of a model which contains two (para) photons, the mass of one of them being non-negligible
Problems of hadron electrodynamics
International Nuclear Information System (INIS)
Rekalo, M.P.
1989-01-01
Certain directions of hadron electrodynamics referring to testing symmetry properties relatively to C-, P- and T-transformations; determination of fundamental electromagnetic characteristics of hadrons as well as to clarifying the dynamics of electromagnetic processes in which hadrons participate are analyzed briefly. 52 refs
Causality in Classical Electrodynamics
Savage, Craig
2012-01-01
Causality in electrodynamics is a subject of some confusion, especially regarding the application of Faraday's law and the Ampere-Maxwell law. This has led to the suggestion that we should not teach students that electric and magnetic fields can cause each other, but rather focus on charges and currents as the causal agents. In this paper I argue…
Johnson, Les; Bilén, Sven G.; Gilchrist, Brian E.; Krause, Linda Habash
2017-09-01
This Special Section of Acta Astronautica contains several peer-reviewed papers selected from among those presented at the Fifth International Conference on Tethers in Space (TiS2016). After a hiatus of 21 years since the last Conference on Tethers in Space, TiS2016 brought together experts, practitioners, and other interested in space tethers and related fields. TiS2016 was held May 24-26, 2016 at The University of Michigan in Ann Arbor, Michigan, U.S.A. Leveraging the hard work of a great many volunteers, the conference co-chairs Prof. Brian Gilchrist and Prof. Sven Bilén welcomed an international contingent with authors from the U.S., Canada, Japan, Spain, China, Finland, Estonia, and Italy. The community provided updates on what has transpired since their last gathering by providing lessons learned; describing new technologies and subsystems; and proposing new tether missions and applications. Papers overviewed de-orbit systems, power generation, orbital maneuvering, momentum capture, debris removal, space tugs, space elevators, collision avoidance, and tether dynamics, among others.
Theoretical physics 3 electrodynamics
Nolting, Wolfgang
2016-01-01
This textbook offers a clear and comprehensive introduction to electrodynamics, one of the core components of undergraduate physics courses. It follows on naturally from the previous volumes in this series. The first part of the book describes the interaction of electric charges and magnetic moments by introducing electro- and magnetostatics. The second part of the book establishes deeper understanding of electrodynamics with the Maxwell equations, quasistationary fields and electromagnetic fields. All sections are accompanied by a detailed introduction to the math needed. Ideally suited to undergraduate students with some grounding in classical and analytical mechanics, the book is enhanced throughout with learning features such as boxed inserts and chapter summaries, with key mathematical derivations highlighted to aid understanding. The text is supported by numerous worked examples and end of chapter problem sets. About the Theoretical Physics series Translated from the renowned and highly successful Germa...
No drama quantum electrodynamics?
International Nuclear Information System (INIS)
Akhmeteli, Andrey
2013-01-01
This article builds on recent work (Akhmeteli in Int. J. Quantum Inf. 9(Supp01):17, 2011; J. Math. Phys. 52:082303, 2011), providing a theory that is based on spinor electrodynamics, is described by a system of partial differential equations in 3+1 dimensions, but reproduces unitary evolution of a quantum field theory in the Fock space. To this end, after introduction of a complex four-potential of electromagnetic field, which generates the same electromagnetic fields as the initial real four-potential, the spinor field is algebraically eliminated from the equations of spinor electrodynamics. It is proven that the resulting equations for electromagnetic field describe independent evolution of the latter and can be embedded into a quantum field theory using a generalized Carleman linearization procedure. The theory provides a simple and at least reasonably realistic model, valuable for interpretation of quantum theory. The issues related to the Bell theorem are discussed. (orig.)
Quantum mechanics and electrodynamics
Zamastil, Jaroslav
2017-01-01
This book highlights the power and elegance of algebraic methods of solving problems in quantum mechanics. It shows that symmetries not only provide elegant solutions to problems that can be solved exactly, but also substantially simplify problems that must be solved approximately. Furthermore, the book provides an elementary exposition of quantum electrodynamics and its application to low-energy physics, along with a thorough analysis of the role of relativistic, magnetic, and quantum electrodynamic effects in atomic spectroscopy. Included are essential derivations made clear through detailed, transparent calculations. The book’s commitment to deriving advanced results with elementary techniques, as well as its inclusion of exercises will enamor it to advanced undergraduate and graduate students.
Electrodynamics an intensive course
Chaichian, Masud; Radu, Daniel; Tureanu, Anca
2016-01-01
This book is devoted to the fundamentals of classical electrodynamics, one of the most beautiful and productive theories in physics. A general survey on the applicability of physical theories shows that only few theories can be compared to electrodynamics. Essentially, all electric and electronic devices used around the world are based on the theory of electromagnetism. It was Maxwell who created, for the first time, a unified description of the electric and magnetic phenomena in his electromagnetic field theory. Remarkably, Maxwell’s theory contained in itself also the relativistic invariance of the special relativity, a fact which was discovered only a few decades later. The present book is an outcome of the authors’ teaching experience over many years in different countries and for different students studying diverse fields of physics. The book is intended for students at the level of undergraduate and graduate studies in physics, astronomy, engineering, applied mathematics and for researchers working ...
Nonlinear electrodynamics and cosmology
International Nuclear Information System (INIS)
Breton, Nora
2010-01-01
Nonlinear electrodynamics (NLED) generalizes Maxwell's theory for strong fields. When coupled to general relativity NLED presents interesting features like the non-vanishing of the trace of the energy-momentum tensor that leads to the possibility of violation of some energy conditions and of acting as a repulsive contribution in the Raychaudhuri equation. This theory is worth to study in cosmological and astrophysical situations characterized by strong electromagnetic and gravitational fields.
Directory of Open Access Journals (Sweden)
Catherine eRabouille
2016-01-01
Full Text Available Originally identified as Golgi stacking factors in vitro, the Golgi reassembly stacking protein (GRASP family has been shown to act as membrane tethers with multiple cellular roles. As an update to previous comprehensive reviews of the GRASP family (Vinke et al., 2011 (Giuliani et al., 2011;Jarvela and Linstedt, 2012, we outline here the latest findings concerning their diverse roles. New insights into the mechanics of GRASP-mediated tethering come from recent crystal structures. The models of how GRASP65 and GRASP55 tether membranes relate directly to their role in Golgi ribbon formation in mammalian cells and the unlinking of the ribbon at the onset of mitosis. However, it is also clear that GRASPs act outside the Golgi with roles at the ER and ER exit sites (ERES. Furthermore, the proteins of this family display other roles upon cellular stress, especially in mediating unconventional secretion of both transmembrane proteins (Golgi bypass and cytoplasmic proteins (through secretory autophagosomes.
Kékedy-Nagy, László; Shipovskov, Stepan; Ferapontova, Elena E
2016-08-16
Charges of redox species can critically affect both the interfacial state of DNA and electrochemistry of DNA-conjugated redox labels and, as a result, the electroanalytical performance of those systems. Here, we show that the kinetics of electron transfer (ET) between the gold electrode and methylene blue (MB) label conjugated to a double-stranded (ds) DNA tethered to gold strongly depend on the charge of the MB molecule, and that affects the performance of genosensors exploiting MB-labeled hairpin DNA beacons. Positively charged MB binds to dsDNA via electrostatic and intercalative/groove binding, and this binding allows the DNA-mediated electrochemistry of MB intercalated into the duplex and, as a result, a complex mode of the electrochemical signal change upon hairpin hybridization to the target DNA, dominated by the "on-off" signal change mode at nanomolar levels of the analyzed DNA. When MB bears an additional carboxylic group, the negative charge provided by this group prevents intimate interactions between MB and DNA, and then the ET in duplexes is limited by the diffusion of the MB-conjugated dsDNA (the phenomenon first shown in Farjami , E. ; Clima , L. ; Gothelf , K. ; Ferapontova , E. E. Anal. Chem. 2011 , 83 , 1594 ) providing the robust "off-on" nanomolar DNA sensing. Those results can be extended to other intercalating redox probes and are of strategic importance for design and development of electrochemical hybridization sensors exploiting DNA nanoswitchable architectures.
T-Rex: A Japanese Space Tether Experiment
Johnson, Les
2009-01-01
Electrodynamic tether (EDT) thrusters work by virtue of the force a magnetic field exerts on a wire carrying an electrical current. The force, which acts on any charged particle moving through a magnetic field (including the electrons moving in a current-carrying wire), were concisely expressed by Lorentz in 1895 in an equation that now bears his name. The force acts in a direction perpendicular to both the direction of current flow and the magnetic field vector. Electric motors make use of this force: a wire loop in a magnetic field is made to rotate by the torque the Lorentz Force exerts on it due to an alternating current in the loop times so as to keep the torque acting in the same sense. The motion of the loop is transmitted to a shaft, thus providing work. Although the working principle of EDT thrusters is not new, its application to space transportation may be significant. In essence, an EDT thruster is just a clever way of getting an electrical current to flow in a long orbiting wire (the tether) so that the Earth s magnetic field will accelerate the wire and, consequently the payload attached to the wire. The direction of current flow in the tether, either toward or away from the Earth along the local vertical, determines whether the magnetic force will raise or lower the orbit. The bias voltage of a vertically deployed metal tether, which results just from its orbital motion (assumed eastward) through Earth s magnetic field, is positive with respect to the ambient plasma at the top and negative at the bottom. This polarization is due to the action of the Lorentz force on the electrons in the tether. Thus, the natural current flow is the result of negative electrons being attracted to the upper end and then returned to the plasma at the lower end. The magnetic force in this case has a component opposite to the direction of motion, and thus leads to a lowering of the orbit and eventually to re-entry. In this generator mode of operation the Lorentz Force
The Science and Applications Tethered Platform (SATP) project
Merlina, P.
1986-01-01
The capabilities of tether systems in orbit are going to be demonstrated by the first planned flights of the Tethered Satellite System (TSS). These test flights will investigate the properties of tether systems as low altitude atmospheric research facilities and as electric power generators. Studies are being conducted with the purpose of testing a variety of concepts and approaches. A comparative analysis of results will allow the choosing of the most promising ideas for further development. The broad range of applications presently under study include applications in electrodynamics, transportation, microgravity in addition to basic research. The SATP project definition study is now about midway through its first phase. The analyses conducted have led to an appraisal of users interest in the project and to a deeper understanding of the problems associated with large, long-lived tether systems in space. In addition, two specialized platform designs, devoted to microgravity and precise pointing applications, are being studied because of their potential usefulness and the promise of technical feasibility.
Implications of rail electrodynamics
International Nuclear Information System (INIS)
Rolader, G.E.; Jamison, K.A.
1990-01-01
A model is developed to investigate possible effects of rail electrodynamics on the performance of railguns. This model describes the oscillatory nature of the rail motion in response to the Lorentz force and the compressive restoration force of material which is behind the rails. In this simple model the rails are found to oscillate with a frequency of β. The rail dynamic behavior induces local electric fields. The authors investigate the significance of these electric fields on stationary particles (lab frame) and on particles moving at the velocity of the plasma/projectile system (projectile frame)
Eringen, A C
1990-01-01
The electrodynamics of continua is a branch ofthe physical sciences concerned with the interaction of electromagnetic fields with deformable bodies. De formable bodies are considered to be continua endowed with continuous distributions of mass and charge. The theory of electromagnetic continua is concerned with the determination of deformations, motions, stress, and elec tromagnetic fields developed in bodies upon the applications of external loads. External loads may be of mechanical origin (e.g., forces, couples, constraints placed on the surface of the body, and initial and boundary conditions arising from thermal and other changes) and/or electromagnetic origin (e.g., electric, magnetic, and current fields). Because bodies of different constitutions respond to external stimuli in a different way, it is imperative to characterize properly the response functions relevant to a given class of continua. This is done by means of the constitutive theory. For example, an elastic dielectric responds to electro...
International Nuclear Information System (INIS)
Waldron, R.A.
1979-01-01
An account is given of Ritz's electrodynamics. Ritz's paper is divided into two parts. In the first he criticises the Lorentz-Maxwell theory based on fields, and comments on alternative theories based on particle interactions. In the second he develops his own theory, also based on particle interactions. He starts from a force law which is analogous to a force law derived by Schwarzschild from the Lorentz theory. While the approach is interesting, it leads to results which do not agree with experimental results obtained several decades later, after Ritz's death. A similar approach is applied to gravitation and is shown to be capable of explaining the anomalous precession of the planet Mercury. (Auth.)
Space tether dynamics: an introduction
Denny, Mark
2018-05-01
The dynamics of orbiting tethers (space elevators and skyhooks) is developed from an unusual direction: Lagrangian rather than Newtonian mechanics. These basic results are derived among others: space elevator required length with and without counterweight, location and magnitude of maximum tether tension, skyhook orbital parameters and tether tension. These conceptual devices are being increasingly discussed as technologically feasible; here they make an interesting pedagogical application of Lagrangian mechanics suitable for undergraduate physics students.
Experimental status of quantum electrodynamics
International Nuclear Information System (INIS)
Drell, S.D.
1978-10-01
This review of the experimental status of quantum electrodynamics covers the fine structure constant, the muon g-2 value, the Lamb shift in hydrogen, the finite proton radius, progress in muonium, and positronium. 37 references
Born-Infeld Nonlinear Electrodynamics
International Nuclear Information System (INIS)
Bialynicki-Birula, I.
1999-01-01
This is only a summary of a lecture delivered at the Infeld Centennial Meeting. In the lecture the history of the Born-Infeld nonlinear electrodynamics was presented and some general features of the theory were discussed. (author)
The propagator of stochastic electrodynamics
Cavalleri, G.
1981-01-01
The "elementary propagator" for the position of a free charged particle subject to the zero-point electromagnetic field with Lorentz-invariant spectral density ~ω3 is obtained. The nonstationary process for the position is solved by the stationary process for the acceleration. The dispersion of the position elementary propagator is compared with that of quantum electrodynamics. Finally, the evolution of the probability density is obtained starting from an initial distribution confined in a small volume and with a Gaussian distribution in the velocities. The resulting probability density for the position turns out to be equal, to within radiative corrections, to ψψ* where ψ is the Kennard wave packet. If the radiative corrections are retained, the present result is new since the corresponding expression in quantum electrodynamics has not yet been found. Besides preceding quantum electrodynamics for this problem, no renormalization is required in stochastic electrodynamics.
Advanced action in classical electrodynamics
Boozer, A. D.
2008-01-01
The time evolution of a charged point particle is governed by a second-order integro-differential equation that exhibits advanced effects, in which the particle responds to an external force before the force is applied. In this paper we give a simple physical argument that clarifies the origin and physical meaning of these advanced effects, and we compare ordinary electrodynamics with a toy model of electrodynamics in which advanced effects do not occur.
BRST Quantisation of Histories Electrodynamics
Noltingk, D.
2001-01-01
This paper is a continuation of earlier work where a classical history theory of pure electrodynamics was developed in which the the history fields have \\emph{five} components. The extra component is associated with an extra constraint, thus enlarging the gauge group of histories electrodynamics. In this paper we quantise the classical theory developed previously by two methods. Firstly we quantise the reduced classical history space, to obtain a reduced quantum history theory. Secondly we qu...
Electrodynamics of Magnetoactive Media
International Nuclear Information System (INIS)
Browning, P K
2004-01-01
'Electrodynamics of Magnetoactive Media' is an unusual book in that it cuts across conventional physics discipline boundaries. The unifying theme allowing this is, quite simply, the physics of magnetic fields in various media. I believe the authors are correct in stating that the book is unique in specifically covering electrodynamic phenomena associated with magnetic fields, though of course some of the more elementary aspects are covered in the classical textbooks on electromagnetism, which are duly acknowledged. This interdisciplinarity makes the book very interesting to people with a range of backgrounds. For example, as a plasma physicist, I was familiar with most of the material on plasmas, but liquid crystals and superconductors were entirely new territory for me. These chapters were indeed both accessible and interesting, and it was surprising for me to see how much commonality there is in the physics of these various media. The first part of the book covers some fundamentals of electrodynamics and magnetostatics, and of electromagnetic waves. Most of this material is covered in textbooks on electromagnetism, and some of it is very basic (for example, LRC circuit theory, surely covered in most first year physics courses, is included) but it is perhaps a useful prelude for what is to come. The generic topic of charged particle motion in electromagnetic fields is well covered. Three main magnetoactive media are then discussed: plasmas (focusing on waves), liquid crystals and superconductors. It is all too easy to criticise a book on the grounds of omitted material, but I do feel that a chapter on magnetostatics in plasmas would have been very helpful, covering force-free fields and so on. Some interesting analogies could then have been exploited. For example, I was intrigued to discover an equation for magnetic fields in superconductors (equation (9.36)) which, apart from a change of sign, is identical to the Helmholtz equation used to model linear force
Molecular Structure of Membrane Tethers
Baoukina, Svetlana; Marrink, Siewert J.; Tieleman, D. Peter
2012-01-01
Membrane tethers are nanotubes formed by a lipid bilayer. They play important functional roles in cell biology and provide an experimental window on lipid properties. Tethers have been studied extensively in experiments and described by theoretical models, but their molecular structure remains
Space Station tethered elevator system
Haddock, Michael H.; Anderson, Loren A.; Hosterman, K.; Decresie, E.; Miranda, P.; Hamilton, R.
1989-01-01
The optimized conceptual engineering design of a space station tethered elevator is presented. The tethered elevator is an unmanned, mobile structure which operates on a ten-kilometer tether spanning the distance between Space Station Freedom and a platform. Its capabilities include providing access to residual gravity levels, remote servicing, and transportation to any point along a tether. The report discusses the potential uses, parameters, and evolution of the spacecraft design. Emphasis is placed on the elevator's structural configuration and three major subsystem designs. First, the design of elevator robotics used to aid in elevator operations and tethered experimentation is presented. Second, the design of drive mechanisms used to propel the vehicle is discussed. Third, the design of an onboard self-sufficient power generation and transmission system is addressed.
Cavity quantum electrodynamics
International Nuclear Information System (INIS)
Walther, Herbert; Varcoe, Benjamin T H; Englert, Berthold-Georg; Becker, Thomas
2006-01-01
This paper reviews the work on cavity quantum electrodynamics of free atoms. In recent years, cavity experiments have also been conducted on a variety of solid-state systems resulting in many interesting applications, of which microlasers, photon bandgap structures and quantum dot structures in cavities are outstanding examples. Although these phenomena and systems are very interesting, discussion is limited here to free atoms and mostly single atoms because these systems exhibit clean quantum phenomena and are not disturbed by a variety of other effects. At the centre of our review is the work on the one-atom maser, but we also give a survey of the entire field, using free atoms in order to show the large variety of problems dealt with. The cavity interaction can be separated into two main regimes: the weak coupling in cavity or cavity-like structures with low quality factors Q and the strong coupling when high-Q cavities are involved. The weak coupling leads to modification of spontaneous transitions and level shifts, whereas the strong coupling enables one to observe a periodic exchange of photons between atoms and the radiation field. In this case, atoms and photons are entangled, this being the basis for a variety of phenomena observed, some of them leading to interesting applications in quantum information processing. The cavity experiments with free atoms reached a new domain with the advent of experiments in the visible spectral region. A review on recent achievements in this area is also given
Energy Technology Data Exchange (ETDEWEB)
Munehiro, H
1980-05-29
When driving the carriage of a printer through a rotating motor, there are problems regarding the limited accuracy of the carriage position due to rotation or contraction and ageing of the cable. In order to solve the problem, a direct drive system was proposed, in which the printer carriage is driven by a linear motor. If one wants to keep the motor circuit of such a motor compact, then the magnetic flux density in the air gap must be reduced or the motor travel must be reduced. It is the purpose of this invention to create an electrodynamic linear motor, which on the one hand is compact and light and on the other hand has a relatively high constant force over a large travel. The invention is characterised by the fact that magnetic fields of alternating polarity are generated at equal intervals in the magnetic field, and that the coil arrangement has 2 adjacent coils, whose size corresponds to half the length of each magnetic pole. A logic circuit is provided to select one of the two coils and to determine the direction of the current depending on the signals of a magnetic field sensor on the coil arrangement.
Eringen, A C
1990-01-01
This is the second volume of a two-volume set presenting a unified approach to the electrodynamics of continua, based on the principles of contemporary continuum of physics. The first volume was devoted mainly to the development of the theory and applications to deformable solid media. This volume extends the developments of the first volume to richer and newer grounds. It contains discussions on fluid media, magnetohydrodynamics, eletrohydrodynamics and media with more complicated structures. With the discussion, in the last two chapters, of memory-dependent materials and non-local E-M theory, the authors account for the nonlocal effects arising from motions and fields of material points at past times and at spatially distant points. This discussion is included here to stimulate further research in these important fields, which are presently in development stages. The second volume is self-contained and can be studied without the help of volume I. A section summarizing the constitutive equations and the unde...
The Relation between Classical and Quantum Electrodynamics
Directory of Open Access Journals (Sweden)
Mario Bacelar Valente
2011-01-01
Full Text Available Quantum electrodynamics presents intrinsic limitations in the description of physical processes that make it impossible to recover from it the type of description we have in classical electrodynamics. Hence one cannot consider classical electrodynamics as reducing to quantum electrodynamics and being recovered from it by some sort of limiting procedure. Quantum electrodynamics has to be seen not as an more fundamental theory, but as an upgrade of classical electrodynamics, which permits an extension of classical theory to the description of phenomena that, while being related to the conceptual framework of the classical theory, cannot be addressed from the classical theory.
The effects of tether placement on antibody stability on surfaces
Grawe, Rebecca W.; Knotts, Thomas A.
2017-06-01
Despite their potential benefits, antibody microarrays have fallen short of performing reliably and have not found widespread use outside of the research setting. Experimental techniques have been unable to determine what is occurring on the surface of an atomic level, so molecular simulation has emerged as the primary method of investigating protein/surface interactions. Simulations of small proteins have indicated that the stability of the protein is a function of the residue on the protein where a tether is placed. The purpose of this research is to see whether these findings also apply to antibodies, with their greater size and complexity. To determine this, 24 tethering locations were selected on the antibody Protein Data Bank (PDB) ID: 1IGT. Replica exchange simulations were run on two different surfaces, one hydrophobic and one hydrophilic, to determine the degree to which these tethering sites stabilize or destabilize the antibody. Results showed that antibodies tethered to hydrophobic surfaces were in general less stable than antibodies tethered to hydrophilic surfaces. Moreover, the stability of the antibody was a function of the tether location on hydrophobic surfaces but not hydrophilic surfaces.
Long-term evaluation of intraoperative neurophysiological monitoring-assisted tethered cord surgery
Dulfer, S E; Drost, G; Lange, F; Journee, H L; Wapstra, F H; Hoving, E W
2017-01-01
PURPOSE: Patients with tethered spinal cord have been investigated for short-term effects after tethered spinal cord surgery in the past. However, little is known about the long-term effects in this patient group. In this retrospective, longitudinal, observational study, a patient sample of a
Tether Elevator Crawler Systems (TECS)
Swenson, Frank R.
1987-01-01
One of the needs of the experimenters on the space station is access to steady and controlled-variation microgravity environments. A method of providing these environments is to place the experiment on a tether attached to the space station. This provides a high degree of isolation from structural oscillations and vibrations. Crawlers can move these experiments along the tethers to preferred locations, much like an elevator. This report describes the motion control laws developed for these crawlers and the testing of laboratory models of these tether elevator crawlers.
Scalar formalism for quantum electrodynamics
International Nuclear Information System (INIS)
Hostler, L.C.
1985-01-01
A set of Feynman rules, similar to the rules of scalar electrodynamics, is derived for a full quantum electrodynamics based on the relativistic Klein--Gordon--type wave equation ]Pi/sub μ/Pi/sub μ/+m 2 +ie sigma x (E +iB)]phi = 0, Pi/sub μ/ equivalent-i partial/sub μ/-eA/sub μ/, for spin- 1/2 particles [J. Math. Phys. 23, 1179 (1982); J. Math. Phys. 24, 2366 (1983)]. In this equation, phi is a 2 x 1 Pauli spinor and sigma/sub a/, a = 1,2,3, are the usual 2 x 2 Pauli spin matrices. The irreducible self-energy parts are compared to those of conventional quantum electrodynamics
Electrodynamic Dust Shield Demonstrator
Stankie, Charles G.
2013-01-01
The objective of the project was to design and manufacture a device to demonstrate a new technology developed by NASA's Electrostatics and Surface Physics Laboratory. The technology itself is a system which uses magnetic principles to remove regolith dust from its surface. This project was to create an enclosure that will be used to demonstrate the effectiveness of the invention to The Office of the Chief Technologist. ONE of the most important challenges of space exploration is actually caused by something very small and seemingly insignificant. Dust in space, most notably on the moon and Mars, has caused many unforeseen issues. Dirt and dust on Earth, while a nuisance, can be easily cleaned and kept at bay. However, there is considerably less weathering and erosion in space. As a result, the microscopic particles are extremely rough and abrasive. They are also electrostatically charged, so they cling to everything they make contact with. This was first noted to be a major problem during the Apollo missions. Dust would stick to the spacesuits, and could not be wiped off as predicted. Dust was brought back into the spacecraft, and was even inhaled by astronauts. This is a major health hazard. Atmospheric storms and other events can also cause dust to coat surfaces of spacecraft. This can cause abrasive damage to the craft. The coating can also reduce the effectiveness of thermal insulation and solar panels.' A group of engineers at Kennedy Space Center's Electrostatics and Surface Physics Laboratory have developed a new technology, called the Electrodynamic Dust Shield, to help alleviate these problems. It is based off of the electric curtain concept developed at NASA in 1967. "The EDS is an active dust mitigation technology that uses traveling electric fields to transport electrostatically charged dust particles along surfaces. To generate the traveling electric fields, the EDS consists of a multilayer dielectric coating with an embedded thin electrode grid
Radiation damping and decoherence in quantum electrodynamics
International Nuclear Information System (INIS)
Breuer, H.P.
2000-01-01
The processes of radiation damping and decoherence in quantum electrodynamics are studied from an open system's point of view. Employing functional techniques of field theory, the degrees of freedom of the radiation field are eliminated to obtain the influence phase functional which describes the reduced dynamics of the matter variables. The general theory is applied to the dynamics of a single electron in the radiation field. From a study of the wave packet dynamics a quantitative measure for the degree of decoherence, the decoherence function, is deduced. The latter is shown to describe the emergence of decoherence through the emission of bremsstrahlung caused by the relative motion of interfering wave packets. It is argued that this mechanism is the most fundamental process in quantum electrodynamics leading to the destruction of coherence, since it dominates for short times and because it is at work even in the electromagnetic field vacuum at zero temperature. It turns out that decoherence trough bremsstrahlung is very small for single electrons but extremely large for superpositions of many-particle states. (orig.)
Cosmological effects of nonlinear electrodynamics
International Nuclear Information System (INIS)
Novello, M; Goulart, E; Salim, J M; Bergliaffa, S E Perez
2007-01-01
It will be shown that a given realization of nonlinear electrodynamics, used as a source of Einstein's equations, generates a cosmological model with interesting features, namely a phase of current cosmic acceleration, and the absence of an initial singularity, thus pointing to a way of solving two important problems in cosmology
Reassessment of Bohm's quantum electrodynamics
International Nuclear Information System (INIS)
Baumann, K.
1986-01-01
Bohm's interpretation of quantum theory is reexamined, with emphasis on quantum electrodynamics. Subjects of the discussion are the observability of 'hidden' variables, the applicability of Bohm's theory to spinor QED, the violation of Lorentz invariance, and variants of Bohm's theory. A formulation of causal quantum field theory in terms of distributions is also presented. (Author)
Spectral ansatz in quantum electrodynamics
International Nuclear Information System (INIS)
Atkinson, D.; Slim, H.A.
1979-01-01
An ansatz of Delbourgo and Salam for the spectral representation of the vertex function in quantum electrodynamics. The Ward-Takahashi identity is respected, and the electron propagator does not have a ghost. The infra-red and ultraviolet behaviours of the electron propagator in this theory are considered, and a rigorous existence theorem for the propagator in the Yennie gauge is presented
Position Control of an X4-Flyer Using a Tether
Directory of Open Access Journals (Sweden)
, Keigo Watanabe
2014-10-01
Full Text Available In Japan, aging of infrastructures, such as roads, bridges, and water and sewer services, etc. poses a problem, and it is required to extend the life-span of such infrastructures by maintenance. Among infrastructures, especially bridges are periodically inspected by short range visual observations, which check the damage and deterioration of the surface. However, since there are some cases where the short range visual observation is difficult, an alternative method is required so as to replace the short range visual observation with it. So, "X4-Flyer" is very attractive because of realizing a movement at high altitude easily. The objective of this study is to develop a tethered X4- Flyer, so that the conventional short range visual observation of bridges is replaced by it. In this paper, a method for the measurement and control of the position is described by using a tether for controlling the position of the X4-Flyer. In addition, it is checked whether the tethered X4-Flyer can control the position using the proposed method or not, letting it fly in a state in which a tether is being attached.
Tether applications for space station
Nobles, W.
1986-01-01
A wide variety of space station applications for tethers were reviewed. Many will affect the operation of the station itself while others are in the category of research or scientific platforms. One of the most expensive aspects of operating the space station will be the continuing shuttle traffic to transport logistic supplies and payloads to the space station. If a means can be found to use tethers to improve the efficiency of that transportation operation, it will increase the operating efficiency of the system and reduce the overall cost of the space station. The concept studied consists of using a tether to lower the shuttle from the space station. This results in a transfer of angular momentum and energy from the orbiter to the space station. The consequences of this transfer is studied and how beneficial use can be made of it.
Zahnle, Kevin; Lupu, Roxana Elena; Dubrovolskis, A. R.
2014-01-01
that the Moon's orbit evolves is limited by the modest radiative cooling rate of Earth's atmosphere, which in effect tethers the Moon to the Earth. Consequently the Moon's orbit evolves orders of magnitude more slowly than in conventional models. Slow orbital evolution promotes capture by orbital resonances that may have been important in the Earth-Moon system
Quantum electrodynamics with compensating current
Energy Technology Data Exchange (ETDEWEB)
Bechler, A [Warsaw Univ. (Poland). Instytut Fizyki Teoretycznej
1974-01-01
A formulation of quantum electrodynamics is proposed in which all the propagators and field operators are gauge invariant. It is based on an old idea of Heisenberg and Euler which consists in the introduction of the linear integrals of potentials as arguments of the exponential functions. This method is generalized by an introduction of the so-called ''compensating currents'', which ensure local, i.e. in every point of space-time, charge conservation. The linear integral method is a particular case of that proposed in this paper. As the starting point we use quantum electrodynamics with a non-zero, small photon mass (Proca theory). It is shown that, due to the presence of the compensating current, the theory is fully renormalizable in Hilbert space with positive definite scalar product. The problem of the definition of the current operator is also briefly discussed.
Electrodynamics and Spacetime Geometry: Foundations
Cabral, Francisco; Lobo, Francisco S. N.
2017-02-01
We explore the intimate connection between spacetime geometry and electrodynamics. This link is already implicit in the constitutive relations between the field strengths and excitations, which are an essential part of the axiomatic structure of electromagnetism, clearly formulated via integration theory and differential forms. We review the foundations of classical electromagnetism based on charge and magnetic flux conservation, the Lorentz force and the constitutive relations. These relations introduce the conformal part of the metric and allow the study of electrodynamics for specific spacetime geometries. At the foundational level, we discuss the possibility of generalizing the vacuum constitutive relations, by relaxing the fixed conditions of homogeneity and isotropy, and by assuming that the symmetry properties of the electro-vacuum follow the spacetime isometries. The implications of this extension are briefly discussed in the context of the intimate connection between electromagnetism and the geometry (and causal structure) of spacetime.
Accelerator and Electrodynamics Capability Review
International Nuclear Information System (INIS)
Jones, Kevin W.
2010-01-01
Los Alamos National Laboratory (LANL) uses capability reviews to assess the science, technology and engineering (STE) quality and institutional integration and to advise Laboratory Management on the current and future health of the STE. Capability reviews address the STE integration that LANL uses to meet mission requirements. The Capability Review Committees serve a dual role of providing assessment of the Laboratory's technical contributions and integration towards its missions and providing advice to Laboratory Management. The assessments and advice are documented in reports prepared by the Capability Review Committees that are delivered to the Director and to the Principal Associate Director for Science, Technology and Engineering (PADSTE). Laboratory Management will use this report for STE assessment and planning. LANL has defined fifteen STE capabilities. Electrodynamics and Accelerators is one of the seven STE capabilities that LANL Management (Director, PADSTE, technical Associate Directors) has identified for review in Fiscal Year (FY) 2010. Accelerators and electrodynamics at LANL comprise a blend of large-scale facilities and innovative small-scale research with a growing focus on national security applications. This review is organized into five topical areas: (1) Free Electron Lasers; (2) Linear Accelerator Science and Technology; (3) Advanced Electromagnetics; (4) Next Generation Accelerator Concepts; and (5) National Security Accelerator Applications. The focus is on innovative technology with an emphasis on applications relevant to Laboratory mission. The role of Laboratory Directed Research and Development (LDRD) in support of accelerators/electrodynamics will be discussed. The review provides an opportunity for interaction with early career staff. Program sponsors and customers will provide their input on the value of the accelerator and electrodynamics capability to the Laboratory mission.
Compton Operator in Quantum Electrodynamics
International Nuclear Information System (INIS)
Garcia, Hector Luna; Garcia, Luz Maria
2015-01-01
In the frame in the quantum electrodynamics exist four basic operators; the electron self-energy, vacuum polarization, vertex correction, and the Compton operator. The first three operators are very important by its relation with renormalized and Ward identity. However, the Compton operator has equal importance, but without divergence, and little attention has been given it. We have calculated the Compton operator and obtained the closed expression for it in the frame of dimensionally continuous integration and hypergeometric functions
Electrodynamics on extrasolar giant planets
Energy Technology Data Exchange (ETDEWEB)
Koskinen, T. T.; Yelle, R. V. [Lunar and Planetary Laboratory, University of Arizona, 1629 East University Boulevard, Tucson, AZ 85721-0092 (United States); Lavvas, P. [Groupe de Spectroscopie Moléculaire et Atmosphérique UMR CNRS 7331, Université Reims Champagne-Ardenne, F-51687 Reims (France); Cho, J. Y-K., E-mail: tommi@lpl.arizona.edu [Astronomy Unit, School of Mathematical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom)
2014-11-20
Strong ionization on close-in extrasolar giant planets (EGPs) suggests that their atmospheres may be affected by ion drag and resistive heating arising from wind-driven electrodynamics. Recent models of ion drag on these planets, however, are based on thermal ionization only and do not include the upper atmosphere above the 1 mbar level. These models are also based on simplified equations of resistive magnetohydrodynamics that are not always valid in extrasolar planet atmospheres. We show that photoionization dominates over thermal ionization over much of the dayside atmosphere above the 100 mbar level, creating an upper ionosphere dominated by ionization of H and He and a lower ionosphere dominated by ionization of metals such as Na, K, and Mg. The resulting dayside electron densities on close-in exoplanets are higher than those encountered in any planetary ionosphere of the solar system, and the conductivities are comparable to the chromosphere of the Sun. Based on these results and assumed magnetic fields, we constrain the conductivity regimes on close-in EGPs and use a generalized Ohm's law to study the basic effects of electrodynamics in their atmospheres. We find that ion drag is important above the 10 mbar level where it can also significantly alter the energy balance through resistive heating. Due to frequent collisions of the electrons and ions with the neutral atmosphere, however, ion drag is largely negligible in the lower atmosphere below the 10 mbar level for a reasonable range of planetary magnetic moments. We find that the atmospheric conductivity decreases by several orders of magnitude in the night side of tidally locked planets, leading to a potentially interesting large-scale dichotomy in electrodynamics between the day and night sides. A combined approach that relies on UV observations of the upper atmosphere, phase curve and Doppler measurements of global dynamics, and visual transit observations to probe the alkali metals can potentially
Quantum electrodynamics and light rays
International Nuclear Information System (INIS)
Sudarshan, E.C.G.
1978-11-01
Light is a quantum electrodynamic entity and hence bundles of rays must be describable in this framework. The duality in the description of elementary optical phenomena is demonstrated in terms of two-point correlation functions and in terms of collections of light rays. The generalizations necessary to deal with two-slit interference and diffraction by a rectangular slit are worked out and the usefulness of the notion of rays of darkness illustrated. 10 references
Accelerator and electrodynamics capability review
Energy Technology Data Exchange (ETDEWEB)
Jones, Kevin W [Los Alamos National Laboratory
2010-01-01
Los Alamos National Laboratory (LANL) uses capability reviews to assess the science, technology and engineering (STE) quality and institutional integration and to advise Laboratory Management on the current and future health of the STE. Capability reviews address the STE integration that LANL uses to meet mission requirements. The Capability Review Committees serve a dual role of providing assessment of the Laboratory's technical contributions and integration towards its missions and providing advice to Laboratory Management. The assessments and advice are documented in reports prepared by the Capability Review Committees that are delivered to the Director and to the Principal Associate Director for Science, Technology and Engineering (PADSTE). Laboratory Management will use this report for STE assessment and planning. LANL has defined fifteen STE capabilities. Electrodynamics and Accelerators is one of the seven STE capabilities that LANL Management (Director, PADSTE, technical Associate Directors) has identified for review in Fiscal Year (FY) 2010. Accelerators and electrodynamics at LANL comprise a blend of large-scale facilities and innovative small-scale research with a growing focus on national security applications. This review is organized into five topical areas: (1) Free Electron Lasers; (2) Linear Accelerator Science and Technology; (3) Advanced Electromagnetics; (4) Next Generation Accelerator Concepts; and (5) National Security Accelerator Applications. The focus is on innovative technology with an emphasis on applications relevant to Laboratory mission. The role of Laboratory Directed Research and Development (LDRD) in support of accelerators/electrodynamics will be discussed. The review provides an opportunity for interaction with early career staff. Program sponsors and customers will provide their input on the value of the accelerator and electrodynamics capability to the Laboratory mission.
Enabling Tethered Exploration on Mars, Phase I
National Aeronautics and Space Administration — Strong science motivations exist for exploring hard to reach terrain on Mars and the leading systems proposed to do so require tethers. While tethers are used...
Selected Tether Applications Cost Model
Keeley, Michael G.
1988-01-01
Diverse cost-estimating techniques and data combined into single program. Selected Tether Applications Cost Model (STACOM 1.0) is interactive accounting software tool providing means for combining several independent cost-estimating programs into fully-integrated mathematical model capable of assessing costs, analyzing benefits, providing file-handling utilities, and putting out information in text and graphical forms to screen, printer, or plotter. Program based on Lotus 1-2-3, version 2.0. Developed to provide clear, concise traceability and visibility into methodology and rationale for estimating costs and benefits of operations of Space Station tether deployer system.
Atmospheric Electricity and Tethered Aerostats, Volume 1
1976-05-11
CATALOG NUMBER AFETR -TR-76-07 __ 4. TITLE (and Subtitle) -. TYPE OF REPORT & PERIOD COVERED ATMOSPHERIC ELECTRICITY AND TETHERED AEROSTATS, FINAL. 1...Electricity Faraday Capes Balloons Lightning Effects , Protection, Warning Systems Conducting and Non-Conducting ’Tethers Potential Geadient Anomalies...and identifying feasible protective systems. After a brief introductory section math models of effects of tethered balloons on surrounding
ELECTRODYNAMIC STABILITY COMPUTATIONS FOR FLEXIBLE CONDUCTORS OF THE AERIAL LINES
Directory of Open Access Journals (Sweden)
I. I. Sergey
2015-01-01
Full Text Available In aerial transmission lines aluminium multiwire conductors are in use. Owing to their flexible design the electrodynamic effect of short circuit currents may lead to intolerable mutual rendezvous and even cross-whipping of the phase conductors. The increasing motion of the conductors caused by effect of the short-circuit electrodynamic force impulse is accompanied by the dynamic load impact affecting the conductors, insulating and supporting constructions of the aerial lines. Intensity of the short-circuit currents electrodynamic impact on the flexible conductors depends on the short circuit current magnitude. For research into electrodynamic endurance of the conductors of the aerial lines located at the vertices of arbitrary triangle with spans of a large length, the authors assume the conductor analytical model in the form of a flexible tensile thread whose mass is distributed evenly lengthwise the conductor. With this analytical model, by the action of the imposed forces the conductor assumes the form conditioned by the diagram of applied external forces, and resists neither bending nor torsion. The initial conditions calculation task reduces to solving the flexible thread statics equations. The law of motion of the conductor marginal points comes out of the conjoint solution of dynamic equations of the conductor and structural components of the areal electric power lines. Based on the proposed algorithm, the researchers of the Chair of the Electric Power Stations of BNTU developed a software program LINEDYS+, which in its characteristics yields to no foreign analogs, e. g. SAMSEF. To calculate the initial conditions they modified a software program computing the flexible conductor mechanics named MR 21. The conductor short-circuit electrodynamic interaction estimation considers structural elements of the areal lines, ice and wind loads, objective parameters of the short circuit. The software programs are accommodated with the simple and
Viking investigations of auroral electrodynamical processes
International Nuclear Information System (INIS)
Marklund, G.
1993-01-01
Recent results from the Viking electric field experiment and their contribution to a better understanding of the aurora and of associated ionosphere-magnetosphere processes are briefly reviewed. The high-resolution electric field data have provided new and important results in a number of different areas, including auroral electrodynamics both on the arc scale size and on the global scale, the auroral acceleration process, the current-voltage relationship, substorms, and the dynamics of the polar cusp. After a short introduction presenting some of the characteristic features of the high-altitude electric field data the remainder of this paper focuses on the role of the electric field in auroral electrodynamics and in the auroral acceleration process. The relationships between the auroral emissions and the associated electric field, current, particle, and conductivity distributions are discussed for both small-scale and large-scale auroral distributions on the basis of results from Viking event studies and from numerical model studies. Particular attention is paid to ionospheric convection and field- aligned current signatures associated with northward interplanetary magnetic field (IMF) auroral distributions, such as the theta aurora or those characterized by extended auroral activity poleward of the classical auroral oval. The role of dc electric fields for the auroral acceleration process has been further investigated and clarified. Intense low-frequency electric field fluctuations (< l Hz) have been shown to play an important role in the auroral acceleration process. In this frequency range the electric field appears static for the electrons but not for the ions, giving rise to a selective acceleration. Estimates of the acceleration potential based on a number of different methods generally show good agreement, providing convincing evidence of the role of dc electric fields in the auroral acceleration process
Electrodynamics of the event horizon
International Nuclear Information System (INIS)
Punsly, B.; Coroniti, F.V.
1989-01-01
This paper is an investigation of the electrodynamics of the event horizon of a Kerr black hole. It is demonstrated that the event horizon behaves quite generally as an asymptotic vacuum infinity for axisymmetric, charge-neutral, accreting electromagnetic sources. This is in contrast with the general notion that the event horizon can be treated as an imperfect conductive membrane with a surface impedance of 4π/c. The conductive-membrane model has been incorporated into the more sophisticated membrane paradigm of Thorne, Price, and Macdonald by supplementing the model with the full equations of general relativity. In certain situations (in particular those of astrophysical interest), the conductive-membrane interpretation forms the appropriate set of pictures and images in the membrane paradigm. In this paper we reevaluate the specific gedanken experiments that were originally used to motivate the paradigm. We find that great care must be exercised if the detailed interaction of a black hole's external gravitational field with a magnetized plasma is modeled by the electrodynamics of the conductive horizon membrane. For ingoing flows of plasma or electromagnetic waves (when the hole is passively accepting information), the interpretation of the horizon as a vacuum infinity is equivalent to an imperfect conductor with a surface impedance of 4π/c (the impedance of the vacuum). In situations when an imperfect conductor should radiate information (such as a Faraday wheel) the event horizon cannot, since it is an infinity. The event horizon does not behave quite generally as an imperfect conductor, but has electrodynamic properties unique to itself
Electrodynamics at the highest energies
International Nuclear Information System (INIS)
Klein, Spencer R.
2002-01-01
At very high energies, the bremsstrahlung and pair production cross sections exhibit complex behavior due to the material in which the interactions occur. The cross sections in dense media can be dramatically different than for isolated atoms. This writeup discusses these in-medium effects, emphasizing how the cross section has different energy and target density dependencies in different regimes. Data from SLAC experiment E-146 will be presented to confirm the energy and density scaling. Finally, QCD analogs of the electrodynamics effects will be discussed
Quantum electrodynamics with unstable vacuum
Energy Technology Data Exchange (ETDEWEB)
Fradkin, E.S. (P.N. Lebedev Physical Inst., USSR Academy of Sciences, Moscow (USSR)); Gitman, D.M. (Moscow Inst. of Radio Engineering Electronics and Automation (USSR)); Shvartsman, Sh.M. (Tomsk State Pedagogical Inst. (USSR))
1991-01-01
Intense external fields destabilize vacuum inducing the creation of particle pairs. In this book the formalism of quantum electrodynamics (QED), using a special perturbation theory with matrix propagators, is systematically analyzed for such systems. The developed approach is, however, general for any quantum field with unstable vacuum. The authors propose solutions for real pair-creating fields. They discuss the general form for the causal function and many other Green's functions, as well as methods for finding them. Analogies to the optical theorem and rules for computing total probabilities are given, as are solutions for non-Abelian theories. (orig.).
Excited states in stochastic electrodynamics
International Nuclear Information System (INIS)
Franca, H.M.; Marshall, T.W.
1987-12-01
It is shown that the set of Wigner functions associated with the excited states of the harmonic oscillator constitute a complete set of functions over the phase space. An arbitraty distribution can be expanded in terms of these Wigner functions. By studying the time evolution, according to Stochastic Electrodynamics, of the expansion coefficients, becomes feasible to separate explicity the contributionsof the radiative reaction and the vaccuum field to the Einsten. A coefficients for this system. A simple semiclassical explanation of the Weisskopf-Heitler phenomenon in resonance fluorescence is also supplied. (author) [pt
Some problems of relativistic electrodynamics
International Nuclear Information System (INIS)
Strel'tsov, V.N.
1991-01-01
Some problems of electrodynamics are considered from the point of view of the radar formulation of relativity theory. This formulation is based on light or retarded distances, the increasing of longitudinal sizes of moving objects is its consequence ( e longation formula ) . Based of Lienard-Wiechert potentials it is shown that in terms of retarded distances equipotential surfaces take the form of rotation ellipsoids, stretched in the direction of electric charge motion. The difficulty connected with the appearance of charge in a moving (neutral) current-carrying conductor is overcome. 23 refs.; 4 figs
Minimal theory of quantum electrodynamics
International Nuclear Information System (INIS)
Berrondo, M.; Jauregui, R.
1986-01-01
Within the general framework of the Lehmann-Symanzik-Zimmermann axiomatic field theory, we obtain a simple and coherent formulation of quantum electrodynamics. The definitions of the current densities fulfill the one-particle stability condition, and the commutation relations for the interacting fields are obtained rather than being postulated a priori, thus avoiding the inconsistencies which appear in the canonical formalism. This is possible due to the fact that we use the integral form of the equations of motion in order to compute the propagators and the S matrix. The resulting spectral representations automatically fulfill the correct boundary conditions thus fixing the ubiquitous quasilocal operators in a unique fashion
Position Control of an X4-Flyer Using a Tether
Directory of Open Access Journals (Sweden)
Yusuke Ouchi
2016-05-01
Full Text Available In Japan, aging of infrastructures, such as roads,bridges, and water and sewer services, etc. poses a problem, andit is required to extend the life-span of such infrastructures bymaintenance. Among infrastructures, especially bridges areperiodically inspected by short range visual observations, whichcheck the damage and deterioration of the surface. However,since there are some cases where the short range visualobservation is difficult, an alternative method is required so as toreplace the short range visual observation with it. So, "X4-Flyer"is very attractive because of realizing a movement at high altitudeeasily. The objective of this study is to develop a tethered X4-Flyer, so that the conventional short range visual observation ofbridges is replaced by it. In this paper, a method for themeasurement and control of the position is described by using atether for controlling the position of the X4-Flyer. In addition, itis checked whether the tethered X4-Flyer can control the positionusing the proposed method or not, letting it fly in a state in whicha tether is being attached
Electrodynamics of quantum spin liquids
Dressel, Martin; Pustogow, Andrej
2018-05-01
Quantum spin liquids attract great interest due to their exceptional magnetic properties characterized by the absence of long-range order down to low temperatures despite the strong magnetic interaction. Commonly, these compounds are strongly correlated electron systems, and their electrodynamic response is governed by the Mott gap in the excitation spectrum. Here we summarize and discuss the optical properties of several two-dimensional quantum spin liquid candidates. First we consider the inorganic material herbertsmithite ZnCu3(OH)6Cl2 and related compounds, which crystallize in a kagome lattice. Then we turn to the organic compounds -EtMe3Sb[Pd(dmit)2]2, κ-(BEDT-TTF)2Ag2(CN)3 and κ-(BEDT-TTF)2Cu2(CN)3, where the spins are arranged in an almost perfect triangular lattice, leading to strong frustration. Due to differences in bandwidth, the effective correlation strength varies over a wide range, leading to a rather distinct behavior as far as the electrodynamic properties are concerned. We discuss the spinon contributions to the optical conductivity in comparison to metallic quantum fluctuations in the vicinity of the Mott transition.
Tethered Satellite System Contingency Investigation Board
1992-11-01
The Tethered Satellite System (TSS-1) was launched aboard the Space Shuttle Atlantis (STS-46) on July 31, 1992. During the attempted on-orbit operations, the Tethered Satellite System failed to deploy successfully beyond 256 meters. The satellite was retrieved successfully and was returned on August 6, 1992. The National Aeronautics and Space Administration (NASA) Associate Administrator for Space Flight formed the Tethered Satellite System (TSS-1) Contingency Investigation Board on August 12, 1992. The TSS-1 Contingency Investigation Board was asked to review the anomalies which occurred, to determine the probable cause, and to recommend corrective measures to prevent recurrence. The board was supported by the TSS Systems Working group as identified in MSFC-TSS-11-90, 'Tethered Satellite System (TSS) Contingency Plan'. The board identified five anomalies for investigation: initial failure to retract the U2 umbilical; initial failure to flyaway; unplanned tether deployment stop at 179 meters; unplanned tether deployment stop at 256 meters; and failure to move tether in either direction at 224 meters. Initial observations of the returned flight hardware revealed evidence of mechanical interference by a bolt with the level wind mechanism travel as well as a helical shaped wrap of tether which indicated that the tether had been unwound from the reel beyond the travel by the level wind mechanism. Examination of the detailed mission events from flight data and mission logs related to the initial failure to flyaway and the failure to move in either direction at 224 meters, together with known preflight concerns regarding slack tether, focused the assessment of these anomalies on the upper tether control mechanism. After the second meeting, the board requested the working group to complete and validate a detailed integrated mission sequence to focus the fault tree analysis on a stuck U2 umbilical, level wind mechanical interference, and slack tether in upper tether
Sanger, George F.
1994-01-01
Safety-tether device enables crewmembers on spacecraft to retrieve crewmember drifting away from spacecraft. Alternatively, drifting crewmember who carries device uses it to grasp and return to spacecraft. Also used on Earth. For example, rescuer on vessel or pier uses it to retrieve and haul drowning or unconscious person to safety; drifting person or rescuer in water uses it to grasp and hold onto support.
Membrane tethering complexes in the endosomal system
Directory of Open Access Journals (Sweden)
Anne eSpang
2016-05-01
Full Text Available Vesicles that are generated by endocytic events at the plasma membrane are destined to early endosomes. A prerequisite for proper fusion is the tethering of two membrane entities. Tethering of vesicles to early endosomes is mediated by the CORVET complex, while fusion of late endosomes with lysosomes depends on the HOPS complex. Recycling through the TGN and to the plasma membrane is facilitated by the GARP and EARP complexes, respectively. However, there are other tethering functions in the endosomal system as there are multiple pathways through which proteins can be delivered from endosomes to either the TGN or the plasma membrane. Furthermore, complexes that may be part of novel tethering complexes have been recently identified. Thus it is likely that more tethering factors exist. In this review, I will provide an overview of different tethering complexes of the endosomal system and discuss how they may provide specificity in membrane traffic.
Membrane Tethering Complexes in the Endosomal System
Spang, Anne
2016-01-01
Vesicles that are generated by endocytic events at the plasma membrane are destined to early endosomes. A prerequisite for proper fusion is the tethering of two membrane entities. Tethering of vesicles to early endosomes is mediated by the class C core vacuole/endosome tethering (CORVET) complex, while fusion of late endosomes with lysosomes depends on the homotypic fusion and vacuole protein sorting (HOPS) complex. Recycling through the trans-Golgi network (TGN) and to the plasma membrane is...
Atmospheric Electricity and Tethered Aerostats, Volume 2
1976-05-11
EASTERN TEST RANGE PATRICK AIR FORCE BASE, FLORIDA 11 MAY 1976 028 099 AFETR -TR-76-07 ATMOSPHERIC ELECTRICITY AND ~TETHERED AEROSTATS, VOLUME 11 Range...number) Atmospheric Electricity Lightning- Effects , Protection, Warning Balloons Systems Conducting & Nonconducting Tethers Potential Gradient Anomalies...if necessary and Identify by block number) Part A, "Atmospheric Electrical Effects of and on Tethered Balloon Systems," by Latham includes airborne
Radiative corrections in bumblebee electrodynamics
Directory of Open Access Journals (Sweden)
R.V. Maluf
2015-10-01
Full Text Available We investigate some quantum features of the bumblebee electrodynamics in flat spacetimes. The bumblebee field is a vector field that leads to a spontaneous Lorentz symmetry breaking. For a smooth quadratic potential, the massless excitation (Nambu–Goldstone boson can be identified as the photon, transversal to the vacuum expectation value of the bumblebee field. Besides, there is a massive excitation associated with the longitudinal mode and whose presence leads to instability in the spectrum of the theory. By using the principal-value prescription, we show that no one-loop radiative corrections to the mass term is generated. Moreover, the bumblebee self-energy is not transverse, showing that the propagation of the longitudinal mode cannot be excluded from the effective theory.
Potentialities of Revised Quantum Electrodynamics
Directory of Open Access Journals (Sweden)
Lehnert B.
2013-10-01
Full Text Available The potentialities of a revised quantum electrodynamic theory (RQED earlier established by the author are reconsidered, also in respect to other fundamental theories such as those by Dirac and Higgs. The RQED theory is characterized by intrinsic linear symmetry breaking due to a nonzero divergence of the electric field strength in the vacuum state, as supported by the Zero Point Energy and the experimentally confirmed Casimir force. It includes the results of electron spin and antimatter by Dirac, as well as the rest mass of elementary particles predicted by Higgs in terms of spontaneous nonlinear symmetry breaking. It will here be put into doubt whether the approach by Higgs is the only theory which becomes necessary for explaining the particle rest masses. In addition, RQED theory leads to new results beyond those being available from the theories by Dirac, Higgs and the Standard Model, such as in applications to leptons and the photon.
Experimental status of quantum electrodynamics
International Nuclear Information System (INIS)
Drell, S.D.
1980-01-01
The speech of Drell S. on the symposium dedicated to 60th anniversary of Schwinger J. is presented. The fundamental status of the hero of the day in quantum field theory, which turned into quantum electrodynamics, are stated. The theory has been perfectly experimentally confirmed and now is the main model permitting to explain weak and strong interactions. The attention is paid on the difference between theoretical and experimental values of the electron anomalous magnetic moment (asub(e)) obtained in the sixth order of perturbation theory. It is necessary to carry out calculations in the octic order of the perturbation theory in order to obtain more precise value of asub(e). The theory and the experimental difference is demonstrated on the example of estimation of fine and hyperfine structure of hydrogen, muonium, and positronium
On causal nonrelativistic classical electrodynamics
International Nuclear Information System (INIS)
Goedecke, G.H.
1984-01-01
The differential-difference (DD) motion equations of the causal nonrelativistic classical electrodynamics developed by the author in 1975 are shown to possess only nonrunaway, causal solutions with no discontinuities in particle velocity or position. As an example, the DD equation solution for the problem of an electromagnetic shock incident on an initially stationary charged particle is contrasted with the standard Abraham-Lorentz equation solution. The general Cauchy problem for these DD motion equations is discussed. In general, in order to uniquely determine a solution, the initial data must be more detailed than the standard Cauchy data of initial position and velocity. Conditions are given under which the standard Cauchy data will determine the DD equation solutions to sufficient practical accuracy
Notes on Born-Infeld-type electrodynamics
Kruglov, S. I.
2017-11-01
We propose a new model of nonlinear electrodynamics (NLED) with three parameters. Born-Infeld (BI) electrodynamics and exponential electrodynamics are particular cases of this model. The phenomenon of vacuum birefringence in the external magnetic field is studied. We show that there is no singularity of the electric field at the origin of point-like charged particles. The corrections to Coulomb’s law at r →∞ are obtained. We calculate the total electrostatic energy of charges, for different parameters of the model, which is finite.
Remarks on Heisenberg-Euler-type electrodynamics
Kruglov, S. I.
2017-05-01
We consider Heisenberg-Euler-type model of nonlinear electrodynamics with two parameters. Heisenberg-Euler electrodynamics is a particular case of this model. Corrections to Coulomb’s law at r →∞ are obtained and energy conditions are studied. The total electrostatic energy of charged particles is finite. The charged black hole solution in the framework of nonlinear electrodynamics is investigated. We find the asymptotic of the metric and mass functions at r →∞. Corrections to the Reissner-Nordström solution are obtained.
Triumphs and failures of quantum electrodynamics
International Nuclear Information System (INIS)
Bialynicki-Birula, I.
1996-01-01
Quantum electrodynamics, after more than sixty years since its discovery, still presents challenges and offers rewards to inquiring minds. This presentation describes some theoretical intricacies of this beautiful theory. (author)
REDUCE in elementary particle physics. Quantum electrodynamics
International Nuclear Information System (INIS)
Grozin, A.G.
1990-01-01
This preprint is the second part of the problem book on using REDUCE for calculations of cross sections and decay probabilities in elementary particle physics. It contains examples of calculations in quantum electrodynamics. 5 refs
Electrodynamic energy harvester for electrical transformer's ...
Indian Academy of Sciences (India)
Electrical transformer; electrodynamic; energy harvester; self-powered ...... Kennedy S P and Gordner T 2013 Hot spot studies for sheet wound transformer wind- ... and Lambert F 2011 Powering low-cost utility sensors using energy harvesting.
Relativization of phases in quantum electrodynamics
International Nuclear Information System (INIS)
Lesche, B.
1981-01-01
The idea of relativism is applied to gauge theories in order to eliminate nonphysical degrees of freedom. Spinor electrodynamics is taken as an example to show how this program might be put into practice. (author)
Mobile tethering: Overview, perspectives and challengess
Constantinescu, M.; Onur, E.; Durmus, Y.; Nikou, S.; Reuver, M. de; Bouwman, H.; Djurica, M.; Glatz, P.M.
2014-01-01
Purpose: The purpose of this paper is to analyze mobile tethering from technological and social perspectives. Mobile tethering allows us to share cellular data connection with others over WiFi, Bluetooth or USB. Although the technology is ready and has promising outcomes, service providers and the
Telleman, Gerdien; den Hartog, Laurens
2013-01-01
Aim: This systematic review assessed the implant survival rate of short (<10 mm) dental implants installed in partially edentulous patients. A case report of a short implant in the posterior region have been added. Materials and methods: A search was conducted in the electronic databases of MEDLINE
Axiomatic electrodynamics and microscopic mechanics
International Nuclear Information System (INIS)
Yussouff, M.
1981-04-01
A new approach to theoretical physics, along with the basic formulation of a new MICROSCOPIC MECHANICS for the motion of small charged particles is described in this set of lecture notes. Starting with the classical (Newtonian) mechanics and classical fields, the important but well known properties of Classical Electromagnetic field are discussed up to section 4. The next nection describes the usual radiation damping theory and its difficulties. It is argued that the usual treatment of radiation damping is not valid for small space and time intervals and the true description of motion requires a new type of mechanics - the MICROSCOPIC MECHANICS: Section 6 and 7 are devoted to showing that not only the new microscopic mechanics goes over to Newtonian mechanics in the proper limit, but also it is closely connected with Quantum Mechanics. All the known results of the Schroedinger theory can be reproduced by microscopic mechanics which also gives a clear physical picture. It removes Einstein's famous objections against Quantum Theory and provides a clear distinction between classical and Quantum behavior. Seven Axioms (three on Classical Mechanics, two for Maxwell's theory, one for Relativity and a new Axiom on Radiation damping) are shown to combine Classical Mechanics, Maxwellian Electrodynamics, Relativity and Schroedinger's Quantum Theory within a single theoretical framework under Microscopic Mechanics which awaits further development at the present time. (orig.)
Nonlinear electrodynamics and CMB polarization
Energy Technology Data Exchange (ETDEWEB)
Cuesta, Herman J. Mosquera [Departmento de Física Universidade Estadual Vale do Acaraú, Avenida da Universidade 850, Campus da Betânia, CEP 62.040-370, Sobral, Ceará (Brazil); Lambiase, G., E-mail: herman@icra.it, E-mail: lambiase@sa.infn.it [Dipartimento di Fisica ' ' E.R. Caianiello' ' , Università di Salerno, 84081 Baronissi (Italy)
2011-03-01
Recently WMAP and BOOMERanG experiments have set stringent constraints on the polarization angle of photons propagating in an expanding universe: Δα = (−2.4±1.9)°. The polarization of the Cosmic Microwave Background radiation (CMB) is reviewed in the context of nonlinear electrodynamics (NLED). We compute the polarization angle of photons propagating in a cosmological background with planar symmetry. For this purpose, we use the Pagels-Tomboulis (PT) Lagrangian density describing NLED, which has the form L ∼ (X/Λ{sup 4}){sup δ−1} X, where X = ¼F{sub αβ}F{sup αβ}, and δ the parameter featuring the non-Maxwellian character of the PT nonlinear description of the electromagnetic interaction. After looking at the polarization components in the plane orthogonal to the (x)-direction of propagation of the CMB photons, the polarization angle is defined in terms of the eccentricity of the universe, a geometrical property whose evolution on cosmic time (from the last scattering surface to the present) is constrained by the strength of magnetic fields over extragalactic distances.
Thermodynamic potential in quantum electrodynamics
International Nuclear Information System (INIS)
Morley, P.D.
1978-01-01
The thermodynamic potential, Ω, in quantum electrodynamics (QED) is derived using the path-integral formalism. Renormalization of Ω is shown by proving the following theorem: Ω/sub B/(e/sub B/,m/sub B/,T,μ) - Ω/sub B/(e/sub B/,m/sub B/,T = 0,μ = 0) = Ω/sub R/(e/sub R/,m/sub R/,T,μ,S), where B and R refer to bare and renormalized quantities, respectively, and S is the Euclidean subtraction momentum squared. This theorem is proved explicitly to e/sub R/ 4 order and could be analogously extended to any higher order. Renormalization-group equations are derived for Ω/sub R/, and it is shown that perturbation theory in a medium is governed by effective coupling constants which are functions of the density. The behavior of the theory at high densities is governed by the Euclidean ultraviolet behavior of the theory in the vacuum
Tethered Lubricants for Small Systems
Energy Technology Data Exchange (ETDEWEB)
Lynden A. Archer
2006-01-09
The objective of this research project is two-fold. First, to fundamentally understand friction and relaxation dynamics of polymer chains near surfaces; and second, to develop novel self-lubricated substrates suitable for MEMS devices. During the three-year performance period of this study the PI and his students have shown using theory and experiments that systematic introduction of disorder into tethered lubricant coatings (e.g. by using self-assembled monolayer (SAM) mixtures or SAMs with nonlinear, branched architectures) can be used to significantly reduce the friction coefficient of a surface. They have also developed a simple procedure based on dielectric spectroscopy for quantifying the effect of surface disorder on molecular relaxation in lubricant coatings. Details of research accomplishments in each area of the project are described in the body of the report.
Theseus: tethered distributed robotics (TDR)
Digney, Bruce L.; Penzes, Steven G.
2003-09-01
The Defence Research and Development Canada's (DRDC) Autonomous Intelligent System's program conducts research to increase the independence and effectiveness of military vehicles and systems. DRDC-Suffield's Autonomous Land Systems (ALS) is creating new concept vehicles and autonomous control systems for use in outdoor areas, urban streets, urban interiors and urban subspaces. This paper will first give an overview of the ALS program and then give a specific description of the work being done for mobility in urban subspaces. Discussed will be the Theseus: Thethered Distributed Robotics (TDR) system, which will not only manage an unavoidable tether but exploit it for mobility and navigation. Also discussed will be the prototype robot called the Hedgehog, which uses conformal 3D mobility in ducts, sewer pipes, collapsed rubble voids and chimneys.
Dynamic multibody modeling for tethered space elevators
Williams, Paul
2009-08-01
This paper presents a fundamental modeling strategy for dealing with powered and propelled bodies moving along space tethers. The tether is divided into a large number of discrete masses, which are connected by viscoelastic springs. The tether is subject to the full range of forces expected in Earth orbit in a relatively simple manner. Two different models of the elevator dynamics are presented. In order to capture the effect of the elevator moving along the tether, the elevator dynamics are included as a separate body in both models. One model treats the elevator's motion dynamically, where propulsive and friction forces are applied to the elevator body. The second model treats the elevator's motion kinematically, where the distance along the tether is determined by adjusting the lengths of tether on either side of the elevator. The tether model is used to determine optimal configurations for the space elevator. A modal analysis of two different configurations is presented which show that the fundamental mode of oscillation is a pendular one around the anchor point with a period on the order of 160 h for the in-plane motion, and 24 h for the out-of-plane motion. Numerical simulation results of the effects of the elevator moving along the cable are presented for different travel velocities and different elevator masses.
The space station tethered elevator system
Anderson, Loren A.
1989-01-01
The optimized conceptual engineering design of a space station tethered elevator is presented. The elevator is an unmanned mobile structure which operates on a ten kilometer tether spanning the distance between the Space Station and a tethered platform. Elevator capabilities include providing access to residual gravity levels, remote servicing, and transportation to any point along a tether. The potential uses, parameters, and evolution of the spacecraft design are discussed. Engineering development of the tethered elevator is the result of work conducted in the following areas: structural configurations; robotics, drive mechanisms; and power generation and transmission systems. The structural configuration of the elevator is presented. The structure supports, houses, and protects all systems on board the elevator. The implementation of robotics on board the elevator is discussed. Elevator robotics allow for the deployment, retrieval, and manipulation of tethered objects. Robotic manipulators also aid in hooking the elevator on a tether. Critical to the operation of the tethered elevator is the design of its drive mechanisms, which are discussed. Two drivers, located internal to the elevator, propel the vehicle along a tether. These modular components consist of endless toothed belts, shunt-wound motors, regenerative power braking, and computer controlled linear actuators. The designs of self-sufficient power generation and transmission systems are reviewed. Thorough research indicates all components of the elevator will operate under power provided by fuel cells. The fuel cell systems will power the vehicle at seven kilowatts continuously and twelve kilowatts maximally. A set of secondary fuel cells provides redundancy in the unlikely event of a primary system failure. Power storage exists in the form of Nickel-Hydrogen batteries capable of powering the elevator under maximum loads.
Ampere-Neumann electrodynamics of metals
International Nuclear Information System (INIS)
Graneau, P.
1985-01-01
Maxwell described Ampere's force law as the cardinal formula of electrodynamics. This law predicts longitudinal mechanical forces along current streamlines in metallic conductors. The Ampere forces set up tension in wires and busbars and compression in liquid metal. At normal current densities they are negligible but, increasing with the square of current, they become dominant in pulse power circuits. Ampere tension and compression have been revealed by exploding wire experiments, in liquid metal jets at solid - liquid interfaces, and with an electrodynamic pendulum. Ampere stresses are already playing an important role in the development of railguns, fuses, current limiters, opening switches, pulse magnets, and a host of other pulse-power devices. This book outlines the electrodynamic action-at-a-distance theory developed by Ampere, Neumann, Weber and, to some extent, by Maxwell. One chapter describes the 20th century extensions of the theory by Graneau and others
Renormalizable Electrodynamics of Scalar and Vector Mesons. Part II
Salam, Abdus; Delbourgo, Robert
1964-01-01
The "gauge" technique" for solving theories introduced in an earlier paper is applied to scalar and vector electrodynamics. It is shown that for scalar electrodynamics, there is no {lambda}φ*2φ2 infinity in the theory, while with conventional subtractions vector electrodynamics is completely finite. The essential ideas of the gauge technique are explained in section 3, and a preliminary set of rules for finite computation in vector electrodynamics is set out in Eqs. (7.28) - (7.34).
Phobos L1 Operational Tether Experiment (PHLOTE)
National Aeronautics and Space Administration — A sensor package that “floats” just above the surface of Phobos, suspended by a tether from a small spacecraft operating at the Mars/Phobos Lagrange 1 (L1) Point...
Review on Electrodynamic Energy Harvesters—A Classification Approach
Directory of Open Access Journals (Sweden)
Roland Lausecker
2013-04-01
Full Text Available Beginning with a short historical sketch, electrodynamic energy harvesters with focus on vibration generators and volumes below 1dm3 are reviewed. The current challenges to generate up to several milliwatts of power from practically relevant flows and vibrations are addressed, and the variety of available solutions is sketched. Sixty-seven different harvester concepts from more than 130 publications are classified with respect to excitation, additional boundary conditions, design and fabrication. A chronological list of the harvester concepts with corresponding references provides an impression about the developments. Besides resonant harvester concepts, the review includes broadband approaches and mechanisms to harvest from flow. Finally, a short overview of harvesters in applications and first market ready concepts is given.
Quantum classical correspondence in nonrelativistic electrodynamics
International Nuclear Information System (INIS)
Ritchie, B.; Weatherford, C.A.
1999-01-01
A form of classical electrodynamic field exists which gives exact agreement with the operator field of quantum electrodynamics (QED) for the Lamb shift of a harmonically bound point electron. Here it is pointed out that this form of classical theory, with its physically acceptable interpretation, is the result of an unconventional resolution of a mathematically ambiguous term in classical field theory. Finally, a quantum classical correspondence principle is shown to exist in the sense that the classical field and expectation value of the QED operator field are identical, if retardation is neglected in the latter
Numerical modelling of elastic space tethers
DEFF Research Database (Denmark)
Kristiansen, Kristian Uldall; Palmer, P. L.; Roberts, R. M.
2012-01-01
In this paper the importance of the ill-posedness of the classical, non-dissipative massive tether model on an orbiting tether system is studied numerically. The computations document that via the regularisation of bending resistance a more reliable numerical integrator can be produced. Furthermo....... It is also shown that on the slow manifold the dynamics of the satellites are well-approximated by the finite dimensional slack-spring model....
Trace gas measurements from tethered balloon platforms
Bandy, Alan R.; Bandy, Terese L.; Youngbluth, Otto; Owens, Thomas L.
1987-01-01
Instrumentation and chemical sampling and analysis procedures are described for making measurements of atmospheric carbon disulfide in the concentration range 1-1000 pptv from tethered balloon platforms. Results of a study on the CS2 composition of air downward of a saltwater marsh are reported. A method for obtaining the necessary data for solving the budget equations for surface fluxes, chemical formation rates and chemical destruction rates using data acquired from tethered balloon platforms is presented.
Atmosphere-Ionosphere Electrodynamic Coupling
Sorokin, V. M.; Chmyrev, V. M.
observed effects as excitation of plasma density inhomogeneities, field-aligned currents, and ULF/ELF emissions and the modification of electron and ion altitude profiles in the upper ionosphere. The electrodynamic model of the ionosphere modification under the influence of some natural and man-made processes in the atmosphere is also discussed. The model is based on the satellite and ground measurements of electromagnetic field and plasma perturbations and on the data on atmospheric radioactivity and soil gas injection into the atmosphere.
Brownian motion of tethered nanowires.
Ota, Sadao; Li, Tongcang; Li, Yimin; Ye, Ziliang; Labno, Anna; Yin, Xiaobo; Alam, Mohammad-Reza; Zhang, Xiang
2014-05-01
Brownian motion of slender particles near a boundary is ubiquitous in biological systems and in nanomaterial assembly, but the complex hydrodynamic interaction in those systems is still poorly understood. Here, we report experimental and computational studies of the Brownian motion of silicon nanowires tethered on a substrate. An optical interference method enabled direct observation of microscopic rotations of the slender bodies in three dimensions with high angular and temporal resolutions. This quantitative observation revealed anisotropic and angle-dependent hydrodynamic wall effects: rotational diffusivity in inclined and azimuth directions follows different power laws as a function of the length, ∼ L(-2.5) and ∼ L(-3), respectively, and is more hindered for smaller inclined angles. In parallel, we developed an implicit simulation technique that takes the complex wire-wall hydrodynamic interactions into account efficiently, the result of which agreed well with the experimentally observed angle-dependent diffusion. The demonstrated techniques provide a platform for studying the microrheology of soft condensed matters, such as colloidal and biological systems near interfaces, and exploring the optimal self-assembly conditions of nanostructures.
Two-dimensional Yukawa interactions from nonlocal Proca quantum electrodynamics
Alves, Van Sérgio; Macrı, Tommaso; Magalhães, Gabriel C.; Marino, E. C.; Nascimento, Leandro O.
2018-05-01
We derive two versions of an effective model to describe dynamical effects of the Yukawa interaction among Dirac electrons in the plane. Such short-range interaction is obtained by introducing a mass term for the intermediate particle, which may be either scalar or an abelian gauge field, both of them in (3 +1 ) dimensions. Thereafter, we consider that the fermionic matter field propagates only in (2 +1 ) dimensions, whereas the bosonic field is free to propagate out of the plane. Within these assumptions, we apply a mechanism for dimensional reduction, which yields an effective model in (2 +1 ) dimensions. In particular, for the gauge-field case, we use the Stueckelberg mechanism in order to preserve gauge invariance. We refer to this version as nonlocal-Proca quantum electrodynamics (NPQED). For both scalar and gauge cases, the effective models reproduce the usual Yukawa interaction in the static limit. By means of perturbation theory at one loop, we calculate the mass renormalization of the Dirac field. Our model is a generalization of Pseudo quantum electrodynamics (PQED), which is a gauge-field model that provides a Coulomb interaction for two-dimensional electrons. Possibilities of application to Fermi-Bose mixtures in mixed dimensions, using cold atoms, are briefly discussed.
Dyson-Schwinger equations in quantum electrodynamics
International Nuclear Information System (INIS)
Slim, H.A.
1981-01-01
A quantum field theory is completely determined by the knowledge of its Green functions and this thesis is concerned with the Salam and Delbourgo approximation method for the determination of the Green functions. In chapter 2 a Lorentz covariant, canonical formulation for quantum electrodynamics is described. In chapter 3 the definition of the Green functions in quantum electrodynamics is given with a derivation of the Dyson-Schwinger equations. The Ward-Takahashi identities, which are a consequence of current conservation, are derived and finally renormalization is briefly mentioned and the equations for the renormalized quantities are given. The gauge transformations, changing the gauge-parameter, a, discussed in Chapter 2 for the field operators, also have implications for the Green functions, and these are worked out in Chapter 4 for the electron propagator, which is not gauge-invariant. Before developing the main approximation, a simple, non-relativistic model is studied in Chapter 5. It has the feature of being exactly solvable in a way which closely resembles the approximation method of Chapter 6 for relativistic quantum electrodynamics. There the Dyson-Schwinger equations for the electron and photon propagator are studied. In chapter 7, the Johnson-Baker-Willey program of finite quantum electrodynamics is considered, in connection with the Ansatz of Salam and Delbourgo, and the question of a possible fixed point of the coupling constant is considered. In the last chapter, some remarks are made about how the results of the approximation scheme can be improved. (Auth.)
Quantum Hall effect in quantum electrodynamics
International Nuclear Information System (INIS)
Penin, Alexander A.
2009-01-01
We consider the quantum Hall effect in quantum electrodynamics and find a deviation from the quantum-mechanical prediction for the Hall conductivity due to radiative antiscreening of electric charge in an external magnetic field. A weak dependence of the universal von Klitzing constant on the magnetic field strength, which can possibly be observed in a dedicated experiment, is predicted
Electrodynamics of the semiconductor band edge
International Nuclear Information System (INIS)
Stahl, A.; Balslev, I.
1987-01-01
The book is a presentation of an approach to electrodynamics in semiconductors. It describes in detail the coherence phenomena appearing when the electromagnetic wavelength, the electron-hole coherence length and the single-particle wavelength are of the same order of magnitude
Massless quantum electrodynamics: a variational study
International Nuclear Information System (INIS)
Piquini, P.C.
1990-01-01
The variational method was used to study the probable existence of a compound vacuum in quantum electrodynamics. An Ansatz containing a condensate of electron-positron pairs was investigated and an optimization equation for the condensate wave function found. (L.C.J.A.)
Mathematical aspects of field quantization. Quantum electrodynamics
International Nuclear Information System (INIS)
Bongaarts, P.J.M.
1983-01-01
Fundamental mathematical aspects of quantum field theory are discussed. A brief review of various approaches to mathematical problems of quantum electrodynamics is given, preceded by a more extensive account of the development of ideas on the mathematical nature of quantum fields in general, providing an appropriate historical context. (author)
Composed particle model in stochastic electrodynamics
International Nuclear Information System (INIS)
Brunini, S.A.
1985-01-01
We analyse the statistical properties of the non-relativistic motion of a particle that has two constituents having finite nasses and charges. The main interaction is in contact with thermal and zero point radiation of Stochastic Electrodynamics. (M.W.O.) [pt
Bogolyubov axiomatic method in quantum electrodynamics
International Nuclear Information System (INIS)
Bazhanov, V.V.; Pron'ko, G.P.; Solov'ev, L.D.
1979-01-01
A number of problems of quantum electrodynamics are reviewed which permit an exact solution for both strong and electromagnetic interactions. The solutions have been obtained in the framework of the S-matrix method based on the Bogolyubov axiomatic approach supplemented with some axioms which make it possible to extended the field of application of the Bogolyubov approach for quantum electrodynamics. Infrared ''renormalization'' of axioms and fundamental equations of the S-matrix electrodynamics is discussed. Low-energy theorems for matrix elements of radiative operators have been obtained as solutions of fundamental equations. The low-energy theorems are used for describing the electrodynamic phenomena of soft photons. The bremsstrahlung amplitude is found. A generalized threshold theorem is formulated for the Compton scattering amplitude. The results of examining the infrared asymptotics of the charged particle Green functions, the small-angle scattering of charged particles and electromagnetic effects on heavy narrow resonance production are presented. The problems discussed show that the consequences of general principles of the relativistic quantum theory supplemented with requirements on gauge invariance are essentially nontrivial
Quantum-electrodynamics corrections in pionic hydrogen
Schlesser, S.; Le Bigot, E. -O.; Indelicato, P.; Pachucki, K.
2011-01-01
We investigate all pure quantum-electrodynamics corrections to the np --> 1s, n = 2-4 transition energies of pionic hydrogen larger than 1 meV, which requires an accurate evaluation of all relevant contributions up to order alpha 5. These values are needed to extract an accurate strong interaction
Minimal resonator loss for circuit quantum electrodynamics
Barends, R.; Vercruyssen, N.; Endo, A.; De Visser, P.J.; Zijlstra, T.; Klapwijk, T.M.; Diener, P.; Yates, S.J.C.; Baselmans, J.J.A.
2010-01-01
We report quality factors of up to 500x10³ in superconducting resonators at the single photon levels needed for circuit quantum electrodynamics. This result is achieved by using NbTiN and removing the dielectric from regions with high electric fields. As demonstrated by a comparison with Ta, the
Testing Born-Infeld Electrodynamics in Waveguides
International Nuclear Information System (INIS)
Ferraro, Rafael
2007-01-01
Waveguides can be employed to test nonlinear effects in electrodynamics. We solve Born-Infeld equations for TE waves in a rectangular waveguide. We show that the energy velocity acquires a dependence on the amplitude, and harmonic components appear as a consequence of the nonlinear behavior
Hilbert space theory of classical electrodynamics
Indian Academy of Sciences (India)
Hilbert space; Koopman–von Neumann theory; classical electrodynamics. PACS No. 03.50. ... The paper is divided into four sections. Section 2 .... construction of Sudarshan is to be contrasted with that of Koopman and von Neumann. ..... ture from KvN and [16] in this formulation is to define new momentum and coordinate.
Lamb Shift in Nonrelativistic Quantum Electrodynamics.
Grotch, Howard
1981-01-01
The bound electron self-energy or Lamb shift is calculated in nonrelativistic quantum electrodynamics. Retardation is retained and also an interaction previously dropped in other nonrelativistic approaches is kept. Results are finite without introducing a cutoff and lead to a Lamb shift in hydrogen of 1030.9 MHz. (Author/JN)
Students' Difficulties with Vector Calculus in Electrodynamics
Bollen, Laurens; van Kampen, Paul; De Cock, Mieke
2015-01-01
Understanding Maxwell's equations in differential form is of great importance when studying the electrodynamic phenomena discussed in advanced electromagnetism courses. It is therefore necessary that students master the use of vector calculus in physical situations. In this light we investigated the difficulties second year students at KU Leuven…
Atomic physics tests of quantum electrodynamics
International Nuclear Information System (INIS)
Mohr, P.J.
1976-08-01
The tests of quantum electrodynamics derived from bound systems and the free electron and muon magnetic moments are reviewed. The emphasis is on the areas in which recent developments in theory or experiment have taken place. Also determinations of the fine structure constant from the Josephson effect and the fine structure of helium are discussed
Fundamental length, bubble electrons and non-local quantum electrodynamics
International Nuclear Information System (INIS)
Hsu, J.P.; Mac, E.
1977-06-01
Based on the concept of a bubble electron and the approach of Pais and Uhlenbeck, one constructs a finite quantum electrodynamics which is relativistically invariant, macro-causal and unitary. In this model, fields and their interaction are local, but the action function of free fields is nonlocal. The propagators are modified so that a fundamental length L is naturally introduced to physics. The modified static potential is given by V(r) = e/r for r greater than L and V(r) = 0 for r less than L, which is produced by the bubble source r -1 ddelta(r-L)/dr rather than a point source. It is found that L less than 4 x 10 -15 cm. Experimental consequences and modifications of strict causality at short distances, vertical bars 2 vertical bar approximately L 2 , are discussed
The investigation of tethered satellite system dynamics
Lorenzini, E. C.
1986-01-01
The analysis of the rotational dynamics of the satellite was focused on the rotational amplitude increase of the satellite, with respect to the tether, during retrieval. The dependence of the rotational amplitude upon the tether tension variation to the power 1/4 was thoroughly investigated. The damping of rotational oscillations achievable by reel control was also quantified while an alternative solution that makes use of a lever arm attached with a universal joint to the satellite was proposed. Comparison simulations between the Smithsonian Astrophysical Observatory and the Martin Marietta (MMA) computer code of reteival maneuvers were also carried out. The agreement between the two, completely independent, codes was extremely close, demonstrating the reliability of the models. The slack tether dynamics during reel jams was analytically investigated in order to identify the limits of applicability of the SLACK3 computer code to this particular case. Test runs with SLACK3 were also carried out.
Tension waves in tethered satellite cables
Lallman, F. J.
1984-01-01
A one-degree-of-freedom simulation of the Tethered Satellite System (TSS) was programmed using a distributed system model of the tether based on the one-dimensional wave equation. This model represents the time varying tension profile along the tether as the sum of two traveling waves of tension moving in opposite directions. A control loop was devised which combines a deployment rate command with the measured tension at the deployer to produce a smooth, stable rate of deployment of the subsatellite. Simulation results show a buildup of periodic bursts of high frequency oscillation in tension. This report covers the mathematical modelling and simulation results and explains the reason for the observed oscillations. The design of a possible vibration damping device is discussed.
NASA Langley Research Center tethered balloon systems
Owens, Thomas L.; Storey, Richard W.; Youngbluth, Otto
1987-01-01
The NASA Langley Research Center tethered balloon system operations are covered in this report for the period of 1979 through 1983. Meteorological data, ozone concentrations, and other data were obtained from in situ measurements. The large tethered balloon had a lifting capability of 30 kilograms to 2500 meters. The report includes descriptions of the various components of the balloon systems such as the balloons, the sensors, the electronics, and the hardware. Several photographs of the system are included as well as a list of projects including the types of data gathered.
International Nuclear Information System (INIS)
Boyer, T.H.
1975-01-01
The theory of classical electrodynamics with classical electromagnetic zero-point radiation is outlined here under the title random electrodynamics. The work represents a reanalysis of the bounds of validity of classical electron theory which should sharpen the understanding of the connections and distinctions between classical and quantum theories. The new theory of random electrodynamics is a classical electron theory involving Newton's equations for particle motion due to the Lorentz force, and Maxwell's equations for the electromagnetic fields with point particles as sources. However, the theory departs from the classical electron theory of Lorentz in that it adopts a new boundary condition on Maxwell's equations. It is assumed that the homogeneous boundary condition involves random classical electromagnetic radiation with a Lorentz-invariant spectrum, classical electromagnetic zero-point radiation. The implications of random electrodynamics for atomic structure, atomic spectra, and particle-interference effects are discussed on an order-of-magnitude or heuristic level. Some detailed mathematical connections and some merely heuristic connections are noted between random electrodynamics and quantum theory. (U.S.)
The chronicle of the classical electrodynamics
International Nuclear Information System (INIS)
Bassalo, J.M.F.
1984-01-01
In this Chronicle of the classical electrodynamics it is shown how this important branch of classical physics was developed since the mathematical formulation of the electromagnetism empiric laws carried by Maxwell, mainly the laws of Coulomb, Oersted, Ampere, Biot-Savart, Faraday, Henry and Lenz, up to the settlement of the radiation theory, scientific background for the technological development of the wireless telegraphy. Through this chronicle, it is also seen how Maxwell got one of the main results of the past century classical physics - the electromagnetic theory of light -, and how the experimental production of an electromagnetic wave by Hertz, unchained a collection of theoretical papers which explained many experimental results such as dispersion of light, thermical radiation, X-rays and its scattering through the matter. At last, it is still seen that the study of electrodynamics of moving bodies led to the relativity theory, presented by Einstein's famous paper about such subject. (Author) [pt
Foundations of classical and quantum electrodynamics
Toptygin, Igor N
2014-01-01
This advanced textbook covers many fundamental, traditional and new branches of electrodynamics, as well as the related fields of special relativity, quantum mechanics and quantum electrodynamics. The book introduces the material at different levels, oriented towards 3rd–4th year bachelor, master, and PhD students. This is so as to describe the whole complexity of physical phenomena. The required mathematical background is collated in Chapter 1, while the necessary physical background is included in the main text of the corresponding chapters and also given in appendices. It contains approximately 800 examples and problems, many of which are described in detail. Some of these problems are designed for students to work on their own with only the answers and descriptions of results, and may be solved selectively. Equally suitable as a reference for researchers specialized in science and engineering.
Investigation on regulators in quantum electrodynamics
Stora, Raymond Félix
We present in this work three models which are able to suppress the divergences of approximate versions of Quantum Electrodynamics.It is indeed argued that, in view of the smallness of the fine structure constant, not only the first terms of a perturbation expansion, or of an expansion according to the number of particles involved in intermediate states, gives a fair approximattonbut furthermore, that it is in these terms that a breakdown of electrodynamics should be sought. Our goal is to connect the high energy behaviour of relevant physical processes with the suppression of the divergences. Our goal is to connect the high energy behaviour of relevant physical processes with the suppression of the divergences. The first model assumes the existence of a photon cut off, whose observable consequences are clearly stated, and of a fermion out off which, although unable to give a satisfactory ...
Quantum electrodynamics of particles with arbitrary spin
International Nuclear Information System (INIS)
Green, H.S.
1978-01-01
A generalization of quantum electrodynamics is developed for particles of higher spin, with careful attention to the requirements of consistency, causality, unitarity and renormalizability. It is shown that field equations studied previously by the author are expressible in arbitrarily many different forms, which are equivalent in the absence of electromagnetic interactions, but not when electromagnetic coupling is introduced in a gauge-invariant way. A form is chosen which satisfies the requirements of casuality. It is shown how to define a particle density, which is positive-definite in the subspace spanned by solutions of the field equation, and satisifies a Lorentz-invariant conservation law. The quantization and renormalization of the resulting electrodynamics is studied, and is found to require only minor modifications of the existing theory for particles of spin 1/2
On generalized Born-Infeld electrodynamics
International Nuclear Information System (INIS)
Kruglov, S I
2010-01-01
The generalized Born-Infeld electrodynamics with two parameters is investigated. In this model the propagation of a linearly polarized laser beam in the external transverse magnetic field is considered. It was shown that there is the effect of vacuum birefringence, and we evaluate induced ellipticity. The upper bounds on the combination of parameters introduced from the experimental data of BRST and PVLAS Collaborations were obtained. When two parameters are equal to each other, we arrive at Born-Infeld electrodynamics and the effect of vacuum birefringence vanishes. We find the canonical and symmetrical Belinfante energy-momentum tensors. The trace of the energy-momentum tensor is not zero and the dilatation symmetry is broken. The four-divergence of the dilatation current is equal to the trace of the Belinfante energy-momentum tensor and is proportional to the parameter (with the dimension of the field strength) of the model. The dual symmetry is also broken in the model considered.
Conceptual assessment tool for advanced undergraduate electrodynamics
Baily, Charles; Ryan, Qing X.; Astolfi, Cecilia; Pollock, Steven J.
2017-12-01
As part of ongoing investigations into student learning in advanced undergraduate courses, we have developed a conceptual assessment tool for upper-division electrodynamics (E&M II): the Colorado UppeR-division ElectrodyNamics Test (CURrENT). This is a free response, postinstruction diagnostic with 6 multipart questions, an optional 3-question preinstruction test, and accompanying grading rubrics. The instrument's development was guided by faculty-consensus learning goals and research into common student difficulties. It can be used to gauge the effectiveness of transformed pedagogy, and to gain insights into student thinking in the covered topic areas. We present baseline data representing 500 students across 9 institutions, along with validity, reliability, and discrimination measures of the instrument and scoring rubric.
Maxwell equations in conformal invariant electrodynamics
International Nuclear Information System (INIS)
Fradkin, E.S.; AN SSSR, Novosibirsk. Inst. Avtomatiki i Ehlektrometrii); Kozhevnikov, A.A.; Palchik, M.Ya.; Pomeransky, A.A.
1983-01-01
We consider a conformal invariant formulation of quantum electrodynamics. Conformal invariance is achieved with a specific mathematical construction based on the indecomposable representations of the conformal group associated with the electromagnetic potential and current. As a corolary of this construction modified expressions for the 3-point Green functions are obtained which both contain transverse parts. They make it possible to formulate a conformal invariant skeleton perturbation theory. It is also shown that the Euclidean Maxwell equations in conformal electrodynamics are manifestations of its kinematical structure: in the case of the 3-point Green functions these equations follow (up to constants) from the conformal invariance while in the case of higher Green functions they are equivalent to the equality of the kernels of the partial wave expansions. This is the manifestation of the mathematical fast of a (partial) equivalence of the representations associated with the potential, current and the field tensor. (orig.)
Conceptual assessment tool for advanced undergraduate electrodynamics
Directory of Open Access Journals (Sweden)
Charles Baily
2017-09-01
Full Text Available As part of ongoing investigations into student learning in advanced undergraduate courses, we have developed a conceptual assessment tool for upper-division electrodynamics (E&M II: the Colorado UppeR-division ElectrodyNamics Test (CURrENT. This is a free response, postinstruction diagnostic with 6 multipart questions, an optional 3-question preinstruction test, and accompanying grading rubrics. The instrument’s development was guided by faculty-consensus learning goals and research into common student difficulties. It can be used to gauge the effectiveness of transformed pedagogy, and to gain insights into student thinking in the covered topic areas. We present baseline data representing 500 students across 9 institutions, along with validity, reliability, and discrimination measures of the instrument and scoring rubric.
Recent advances in bound state quantum electrodynamics
International Nuclear Information System (INIS)
Brodsky, S.J.; Lepage, G.P.
1977-06-01
Recent developments are reviewed in four areas of computational quantum electrodynamics: a new relativistic two-body formalism equal in rigor to the Bethe-Salpeter formalism but with strong calculational advantages is discussed; recent work on the computation of the decay rate of bound systems (positronium in particular) is presented; limits on possible composite structure of leptons are discussed; a new multidimensional integration program ('VEGAS') suitable for higher order calculations is presented
Problems of Technical Electrodynamics (Selected Articles),
1984-04-11
copy available. ii DC 83143001 PAGE 1 PROBLEMS OF TECHNICAL ELECTRODYNAMICS. DOC - 83143001 PAGE 2 In the collector /collection are connected the...composite/ compound reliable in mechanical sense forgings of rotors with a weight of 250 t and it is more and rotor binding bands. These K forgings must be...go - calculated coefficient, which considers the character of temperature field. With a linear change in temperature .=1, with parabolic =3
Ward-Takahashi identities in quantum electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Nishijima, K; Sasaki, R [Tokyo Univ. (Japan). Dept. of Physics
1975-03-01
The Ward-Takahashi identities are derived for connected Green's functions in quantum electrodynamics without recourse to equal-time commutation relations, field equations and the Feynman-Dyson perturbation expansions. The argument is based on the dispersion formulation of field theories and only finite expressions are used throughout this derivation. These identities are shown to be consequences of the subtraction conditions imposed upon the 2-, 3- and 4-point Green's functions.
Topological solitons in 8-spinor mie electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Rybakov, Yu. P., E-mail: soliton4@mail.ru [Peoples' Friendship University of Russia, Department of Theoretical Physics (Russian Federation)
2013-10-15
We investigate the effective 8-spinor field model suggested earlier as the generalization of nonlinear Mie electrodynamics. We first study in pure spinorial model the existence of topological solitons endowed with the nontrivial Hopf invariant Q{sub H}, which can be interpreted as the lepton number. Electromagnetic field being included as the perturbation, we estimate the energy and the spin of the localized charged configuration.
Some basic problems of quantum electrodynamics
International Nuclear Information System (INIS)
Steinmann, O.
1981-01-01
QED (= quantum electrodynamics) is often said to be one of the most successful theories, if not 'the' most successful one, that we possess in physics. That it is a theory is, however, not yet established beyond possible doubt. In this talk I report on the present state of this problem. The question is whether the computational rules of QED, which stand up so well to all practical tests, can be founded logically in a consistent, exactly formulizable, theory. (orig./HSI)
Self-energy quantum electrodynamics: Multipole radiation
International Nuclear Information System (INIS)
Salamin, Y.I.
1993-01-01
Within the context of Barut's self-field approach to quantum electrodynamics, it is shown that the exact relativistic expression for the Einstein A-coefficient of atomic spontaneous emission reduces, in the long wavelength approximation, to a form containing electric- and magnetic-like multipole contributions related to the transition charge and current distributions of the relativistic electron. A number of interesting features of the expressions involved are discussed, and their generalization to interacting composite systems is also pointed out. 10 refs
On the equation of motion in electrodynamics
International Nuclear Information System (INIS)
Papas, C.H.
1975-01-01
A new vector equation of motion in electrodynamics is proposed by replacing the Schott term in the Lorentz-Dirac equation by an expression depending on the electro-magnetic field vectors E and B and the velocity vector V. It is argued that several conceptual difficulties in the Lorentz-Dirac equation disappear while the results remain the same except for extreme high fields and velocities as could be encountered in astrophysics
Electrodynamics of a Cosmic Dark Fluid
Directory of Open Access Journals (Sweden)
Alexander B. Balakin
2016-06-01
Full Text Available Cosmic Dark Fluid is considered as a non-stationary medium, in which electromagnetic waves propagate, and magneto-electric field structures emerge and evolve. A medium-type representation of the Dark Fluid allows us to involve in its analysis the concepts and mathematical formalism elaborated in the framework of classical covariant electrodynamics of continua, and to distinguish dark analogs of well-known medium-effects, such as optical activity, pyro-electricity, piezo-magnetism, electro- and magneto-striction and dynamo-optical activity. The Dark Fluid is assumed to be formed by a duet of a Dark Matter (a pseudoscalar axionic constituent and Dark Energy (a scalar element; respectively, we distinguish electrodynamic effects induced by these two constituents of the Dark Fluid. The review contains discussions of 10 models, which describe electrodynamic effects induced by Dark Matter and/or Dark Energy. The models are accompanied by examples of exact solutions to the master equations, correspondingly extended; applications are considered for cosmology and space-times with spherical and pp-wave symmetries. In these applications we focused the attention on three main electromagnetic phenomena induced by the Dark Fluid: first, emergence of Longitudinal Magneto-Electric Clusters; second, generation of anomalous electromagnetic responses; third, formation of Dark Epochs in the Universe history.
Relativistic electrodynamics of dissipative elastic media
International Nuclear Information System (INIS)
Kranys, M.
1980-01-01
A phenomenological general relativistic electrodynamics is proposed for a dissipative elastic solid which is polarizable and magnetizable and whose governing equations form a hyperbolic system. Non-stationary transport equations are proposed for dissipative fluxes (and constitutive equations of electrodynamics) containing new cross-effect terms, as required for compatibility with an entropy principle expressed by a new balance equation (including a new Gibbs equation). The dynamic equations are deduced from the unified Minkowski-Abraham-Eckart energy-momentum tensor. The theory, formed by a set of 29 (reducible to 23) partial differential equations (in special relativity) governing the material behaviour of the system characterized by generalizing the constitutive equations of quasineutral media, together with Maxwell's equations, may be referred to as the electrodynamics of dissipative elastic media (or fluid). The proposed transport laws for polarization and magnetization generalize the well-known Debye law for relaxation and show the influence of shear and bulk viscosity on polarization and magentization. Besides the form of the entropy function, the free energy function in the non-stationary regime is also formulated. (auth)
Ionic-Liquid-Tethered Nanoparticles: Hybrid Electrolytes
Moganty, Surya S.
2010-10-22
A new class of solventless electrolytes was created by tethering ionic liquids to hard inorganic ZrO2 nanostructures (see picture; NIM=nanoscale ionic material). These hybrid fluids exhibit exceptional redox stability windows, excellent thermal stability, good lithium transference numbers, long-term interfacial stability in the presence of a lithium anode and, when doped with lithium salt, reasonable ionic conductivities.
Cooperative networks : The mobile tethering game
Constantinescu, M.; Bouwman, H.; Djurica, M.; Durmus, Y.; Onur, E.; Reuver, M. de
2012-01-01
We propose an analysis of cooperation for data sharing and the behavioral aspects involved in the process of decision making. Starting with the tethering capabilities of recent devices we apply game theoretical principles and models, inquire what makes the cooperation work, and what are the
Tethered "kiteplane" design for the Laddermill project
Breukels, J.; Ockels, W.
2005-01-01
The Laddermill is an innovative concept for generating energy from wind using large kite-like wings on a tether. The wings are able to fly in both the regime of airplanes and kites. We therefore call these structures "kiteplanes". By providing a recurring motion with a large lift during ascending
STICS: surface-tethered iterative carbohydrate synthesis.
Pornsuriyasak, Papapida; Ranade, Sneha C; Li, Aixiao; Parlato, M Cristina; Sims, Charles R; Shulga, Olga V; Stine, Keith J; Demchenko, Alexei V
2009-04-14
A new surface-tethered iterative carbohydrate synthesis (STICS) technology is presented in which a surface functionalized 'stick' made of chemically stable high surface area porous gold allows one to perform cost efficient and simple synthesis of oligosaccharide chains; at the end of the synthesis, the oligosaccharide can be cleaved off and the stick reused for subsequent syntheses.
Calculating Payload for a Tethered Balloon System
Charles D. Tangren
1980-01-01
A graph method to calculate payload for a tethered balloon system, with the supporting helium lift and payload equations. is described. The balloon system is designed to collect emissions data during the convective-lift and no-convective-lift phases of a forest fire. A description of the balloon system and a list of factors affecting balloon selection are included....
Tethered Aerostat Effects on Nearby Seismometers
Energy Technology Data Exchange (ETDEWEB)
Bowman, Daniel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2017-12-01
This report assesses seismic interference generated by a tethered aerostat. The study was motivated by a planned aerostat deployment within the footprint of the Dry Alluvium Geology seismic network. No evidence was found for seismic interference generated by the aerostat, and thus the e ects on the Dry Alluvium Geology sensors will be negligible.
Hong, Aaron Aw Teik; Varatharajoo, Renuganth
2015-12-01
The authors would like to thank Dr. N.A. Ismail for some of the discussions found in her thesis as these discussions have facilitated to achieve some of the results published in this article. Therefore, Ismail, N.A., "The Dynamics of a Flexible Motorised Momentum Exchange Tether (MMET)", PhD. thesis, University of Glasgow, UK, pp. 26-41, 2012 is cited accordingly herein. The thesis was missed out from the reference list in the original version of this article due to an oversight with no other intention. Similarly the thesis by Stevens, R.E., "Optimal Control of Electrodynamic Tether Satellites", PhD. thesis, Air Force Institute of Technology, USA, pp. 87-96, 2008 is referred for a further readership completeness.
Transitions of tethered chain molecules under tension.
Luettmer-Strathmann, Jutta; Binder, Kurt
2014-09-21
An applied tension force changes the equilibrium conformations of a polymer chain tethered to a planar substrate and thus affects the adsorption transition as well as the coil-globule and crystallization transitions. Conversely, solvent quality and surface attraction are reflected in equilibrium force-extension curves that can be measured in experiments. To investigate these effects theoretically, we study tethered chains under tension with Wang-Landau simulations of a bond-fluctuation lattice model. Applying our model to pulling experiments on biological molecules we obtain a good description of experimental data in the intermediate force range, where universal features dominate and finite size effects are small. For tethered chains in poor solvent, we observe the predicted two-phase coexistence at transitions from the globule to stretched conformations and also discover direct transitions from crystalline to stretched conformations. A phase portrait for finite chains constructed by evaluating the density of states for a broad range of solvent conditions and tensions shows how increasing tension leads to a disappearance of the globular phase. For chains in good solvents tethered to hard and attractive surfaces we find the predicted scaling with the chain length in the low-force regime and show that our results are well described by an analytical, independent-bond approximation for the bond-fluctuation model for the highest tensions. Finally, for a hard or slightly attractive surface the stretching of a tethered chain is a conformational change that does not correspond to a phase transition. However, when the surface attraction is sufficient to adsorb a chain it will undergo a desorption transition at a critical value of the applied force. Our results for force-induced desorption show the transition to be discontinuous with partially desorbed conformations in the coexistence region.
TMBM: Tethered Micro-Balloons on Mars
Sims, M. H.; Greeley, R.; Cutts, J. A.; Yavrouian, A. H.; Murbach, M.
2000-01-01
The use of balloons/aerobots on Mars has been under consideration for many years. Concepts include deployment during entry into the atmosphere from a carrier spacecraft, deployment from a lander, use of super-pressurized systems for long duration flights, 'hot-air' systems, etc. Principal advantages include the ability to obtain high-resolution data of the surface because balloons provide a low-altitude platform which moves relatively slowly. Work conducted within the last few years has removed many of the technical difficulties encountered in deployment and operation of balloons/aerobots on Mars. The concept proposed here (a tethered balloon released from a lander) uses a relatively simple approach which would enable aspects of Martian balloons to be tested while providing useful and potentially unique science results. Tethered Micro-Balloons on Mars (TMBM) would be carried to Mars on board a future lander as a stand-alone experiment having a total mass of one to two kilograms. It would consist of a helium balloon of up to 50 cubic meters that is inflated after landing and initially tethered to the lander. Its primary instrumentation would be a camera that would be carried to an altitude of up to tens of meters above the surface. Imaging data would be transmitted to the lander for inclusion in the mission data stream. The tether would be released in stages allowing different resolutions and coverage. In addition during this staged release a lander camera system may observe the motion of the balloon at various heights above he lander. Under some scenarios upon completion of the primary phase of TMBM operations, the tether would be cut, allowing TMBM to drift away from the landing site, during which images would be taken along the ground.
Tethering factors as organizers of intracellular vesicular traffic.
Yu, I-Mei; Hughson, Frederick M
2010-01-01
Intracellular trafficking entails the budding, transport, tethering, and fusion of transport vesicles and other membrane carriers. Here we review recent progress toward a mechanistic understanding of vesicle tethering. The known tethering factors are large complexes important for one or more intracellular trafficking pathways and are capable of interacting directly with many of the other principal components of the cellular trafficking machinery. Our review emphasizes recent developments in the in vitro reconstitution of vesicle tethering and the structural characterization of multisubunit tethering factors. The combination of these and other approaches has led to exciting progress toward understanding how these essential nanomachines work.
Quantum Electrodynamical Shifts in Multivalent Heavy Ions.
Tupitsyn, I I; Kozlov, M G; Safronova, M S; Shabaev, V M; Dzuba, V A
2016-12-16
The quantum electrodynamics (QED) corrections are directly incorporated into the most accurate treatment of the correlation corrections for ions with complex electronic structure of interest to metrology and tests of fundamental physics. We compared the performance of four different QED potentials for various systems to access the accuracy of QED calculations and to make a prediction of highly charged ion properties urgently needed for planning future experiments. We find that all four potentials give consistent and reliable results for ions of interest. For the strongly bound electrons, the nonlocal potentials are more accurate than the local potential.
Quantum electrodynamics in strong external fields
International Nuclear Information System (INIS)
Mueller, B.; Rafelski, J.; Kirsch, J.
1981-05-01
We review the theoretical description of quantum electrodynamics in the presence of strong and supercritical fields. In particular, the process of the spontaneous vacuum decay accompanied by the observable positron emission in heavy ion collisions is described. Emphasis is put on the proper formulation of many-body aspects in the framework of quantum field theory. The extension of the theory to the description of Bose fields and many-body effects is presented, and the Klein paradox is resolved. Some implications of the theoretical methods developed here are presented concerning non-abelian gauge theories and the quark confinement puzzle. (orig.)
Indefinite metric and regularization of electrodynamics
International Nuclear Information System (INIS)
Gaudin, M.
1984-06-01
The invariant regularization of Pauli and Villars in quantum electrodynamics can be considered as deriving from a local and causal lagrangian theory for spin 1/2 bosons, by introducing an indefinite metric and a condition on the allowed states similar to the Lorentz condition. The consequences are the asymptotic freedom of the photon's propagator. We present a calcultion of the effective charge to the fourth order in the coupling as a function of the auxiliary masses, the theory avoiding all mass divergencies to this order [fr
Electrodynamics in scale-covariant gravity theory
International Nuclear Information System (INIS)
Mansfield, V.N.; Malin, S.
1980-01-01
Utilizing the inherent scale-invariance of Maxwell's Equations, classical electrodynamics is incorporated into the theory of scale-invariant gravity. In this incorporation the gravitational constant G is shown to transform like β -2 (β is the gauge function), the generalized Lorentz Force Law is derived, the electric charge is shown to be invariant under gauge transformation, and matter creation is shown to be a necessity. In all nontrivial gauges a modified version of QED is obtained. The deviation from standard QED, however, is shown to be beyond the range of experimental detection when G α β -2 . (orig.)
Does quantum electrodynamics have an arrow of time?
Atkinson, David
Quantum electrodynamics is a time-symmetric theory that is part of the electroweak interaction, which is invariant under a generalized form of this symmetry, the PCT transformation. The thesis is defended that the arrow of time in electrodynamics is a consequence of the assumption of an initial
Quantum electrodynamics with arbitrary charge on a noncommutative space
International Nuclear Information System (INIS)
Zhou Wanping; Long Zhengwen; Cai Shaohong
2009-01-01
Using the Seiberg-Witten map, we obtain a quantum electrodynamics on a noncommutative space, which has arbitrary charge and keep the gauge invariance to at the leading order in theta. The one-loop divergence and Compton scattering are reinvestigated. The noncommutative effects are larger than those in ordinary noncommutative quantum electrodynamics. (authors)
Electrodynamical Model of Quasi-Efficient Financial Markets
Ilinski, Kirill N.; Stepanenko, Alexander S.
The modelling of financial markets presents a problem which is both theoretically challenging and practically important. The theoretical aspects concern the issue of market efficiency which may even have political implications [1], whilst the practical side of the problem has clear relevance to portfolio management [2] and derivative pricing [3]. Up till now all market models contain "smart money" traders and "noise" traders whose joint activity constitutes the market [4, 5]. On a short time scale this traditional separation does not seem to be realistic, and is hardly acceptable since all high-frequency market participants are professional traders and cannot be separated into "smart" and "noisy." In this paper we present a "microscopic" model with homogenuous quasi-rational behaviour of traders, aiming to describe short time market behaviour. To construct the model we use an analogy between "screening" in quantum electrodynamics and an equilibration process in a market with temporal mispricing [6, 7]. As a result, we obtain the time-dependent distribution function of the returns which is in quantitative agreement with real market data and obeys the anomalous scaling relations recently reported for both high-frequency exchange rates [8], S&P500 [9] and other stock market indices [10, 11].
Nonlinear quantum electrodynamic and electroweak processes in strong laser fields
Energy Technology Data Exchange (ETDEWEB)
Meuren, Sebastian
2015-06-24
Various nonlinear electrodynamic and electroweak processes in strong plane-wave laser fields are considered with an emphasis on short-pulse effects. In particular, the momentum distribution of photoproduced electron-positron pairs is calculated numerically and a semiclassical interpretation of its characteristic features is established. By proving the optical theorem, compact double-integral expressions for the total pair-creation probability are obtained and numerically evaluated. The exponential decay of the photon wave function in a plane wave is included by solving the Schwinger-Dyson equations to leading-order in the quasistatic approximation. In this respect, the polarization operator in a plane wave is investigated and its Ward-Takahashi identity verified. A classical analysis indicates that a photoproduced electron-positron pair recollides for certain initial conditions. The contributions of such recollision processes to the polarization operator are identified and calculated both analytically and numerically. Furthermore, the existence of nontrivial electron-spin dynamics induced by quantum fluctuations is verified for ultra-short laser pulses. Finally, the exchange of weak gauge bosons is considered, which is essential for neutrino-photon interactions. In particular, the axial-vector-vector coupling tensor is calculated and the so-called Adler-Bell-Jackiw (ABJ) anomaly investigated.
A Process Algebra Approach to Quantum Electrodynamics
Sulis, William
2017-12-01
The process algebra program is directed towards developing a realist model of quantum mechanics free of paradoxes, divergences and conceptual confusions. From this perspective, fundamental phenomena are viewed as emerging from primitive informational elements generated by processes. The process algebra has been shown to successfully reproduce scalar non-relativistic quantum mechanics (NRQM) without the usual paradoxes and dualities. NRQM appears as an effective theory which emerges under specific asymptotic limits. Space-time, scalar particle wave functions and the Born rule are all emergent in this framework. In this paper, the process algebra model is reviewed, extended to the relativistic setting, and then applied to the problem of electrodynamics. A semiclassical version is presented in which a Minkowski-like space-time emerges as well as a vector potential that is discrete and photon-like at small scales and near-continuous and wave-like at large scales. QED is viewed as an effective theory at small scales while Maxwell theory becomes an effective theory at large scales. The process algebra version of quantum electrodynamics is intuitive and realist, free from divergences and eliminates the distinction between particle, field and wave. Computations are carried out using the configuration space process covering map, although the connection to second quantization has not been fully explored.
Electrodynamics of spin currents in superconductors
International Nuclear Information System (INIS)
Hirsch, J.E.
2008-01-01
In recent work we formulated a new set of electrodynamic equations for superconductors as an alternative to the conventional London equations, compatible with the prediction of the theory of hole superconductivity that superconductors expel negative charge from the interior towards the surface. Charge expulsion results in a macroscopically inhomogeneous charge distribution and an electric field in the interior, and because of this a spin current is expected to exist. Furthermore, we have recently shown that a dynamical explanation of the Meissner effect in superconductors leads to the prediction that a spontaneous spin current exists near the surface of superconductors (spin Meissner effect). In this paper we extend the electrodynamic equations proposed earlier for the charge density and charge current to describe also the space and time dependence of the spin density and spin current. This allows us to determine the magnitude of the expelled negative charge and interior electric field as well as of the spin current in terms of other measurable properties of superconductors. We also provide a 'geometric' interpretation of the difference between type I and type II superconductors, discuss how superconductors manage to conserve angular momentum, discuss the relationship between our model and Slater's seminal work on superconductivity, and discuss the magnitude of the expected novel effects for elemental and other superconductors. (Abstract Copyright [2008], Wiley Periodicals, Inc.)
A reformulation of mechanics and electrodynamics.
Pinheiro, Mario J
2017-07-01
Classical mechanics, as commonly taught in engineering and science, are confined to the conventional Newtonian theory. But classical mechanics has not really changed in substance since Newton formulation, describing simultaneous rotation and translation of objects with somewhat complicate drawbacks, risking interpretation of forces in non-inertial frames. In this work we introduce a new variational principle for out-of-equilibrium, rotating systems, obtaining a set of two first order differential equations that introduces a thermodynamic-mechanistic time into Newton's dynamical equation, and revealing the same formal symplectic structure shared by classical mechanics, fluid mechanics and thermodynamics. The results is a more consistent formulation of dynamics and electrodynamics, explaining natural phenomena as the outcome from a balance between energy and entropy, embedding translational with rotational motion into a single equation, showing centrifugal and Coriolis force as derivatives from the transport of angular momentum, and offering a natural method to handle variational problems, as shown with the brachistochrone problem. In consequence, a new force term appears, the topological torsion current, important for spacecraft dynamics. We describe a set of solved problems showing the potential of a competing technique, with significant interest to electrodynamics as well. We expect this new approach to have impact in a large class of scientific and technological problems.
δ expansion applied to quantum electrodynamics
International Nuclear Information System (INIS)
Bender, C.M.; Boettcher, S.; Milton, K.A.
1992-01-01
A recently proposed technique known as the δ expansion provides a nonperturbative treatment of a quantum field theory. The δ-expansion approach can be applied to electrodynamics in such a way that local gauge invariance is preserved. In this paper it is shown that for electrodynamic processes involving only external photon lines and no external electron lines the δ expansion is equivalent to a fermion loop expansion. That is, the coefficient of δ n in the δ expansion is precisely the sum of all n-electron-loop Feynman diagrams in a conventional weak-coupling approximation. This equivalence does not extend to processes having external electron lines. When external electron lines are present, the δ expansion is truly nonperturbative and does not have a simple interpretation as a resummation of conventional Feynman diagrams. To illustrate the nonperturbative character of the δ expansion we perform a speculative calculation of the fermion condensate in the massive Schwinger model in the limit of large coupling constant
Rail electrodynamics in a plasma armature railgun
International Nuclear Information System (INIS)
Rolader, G.E.; Jamison, K.A.; Villecco, R.A.; Graham, F.R.
1991-01-01
A model is developed to investigate rail electrodynamics in a plasma armature railgun. This model describes the rail motion in response to the transitory Lorentz force and the compressive restoration force from the material which is between the rails and the containment structure. In this model the distance between the rails is found to oscillate with a frequency of β. The magnetic field and the dynamic behavior of the rails induce local electric fields. We investigate the significance of these electric fields in the laboratory frame and in the projectile frame. In the lab frame, rail electrodynamics induces local electric fields which have maximums spaced behind the projectile at locations where βt p is an odd multiple of π, where t p is the time since the projectile has passed an axial location on the rails. When the projectile is accelerating, rail dynamics induce electric fields in the projectile frame which have maximums where βt p is an even multiple of π. As the projectile velocity increases, the locations of the peak voltages move farther behind the projectile. For the CHECMATE railgun, calculations indicate that the rail displacement is on the order of 2 mm, the rail velocity is on the order of 50 m/s, and the voltages induced in the projectile frame are on the order of 20--40 V
Electrodynamics with a Future Conformal Horizon
International Nuclear Information System (INIS)
Ibison, Michael
2010-01-01
We investigate the impact of singularities occurring at future times in the Friedmann equations expressed in conformal coordinates to determine the consequences of extending the time coordinate through the singularity for the physics of matter and radiation occupying just one side. Mostly this involves investigation of the relationship between the metric with line element ds 2 a 2 (t)(dt 2 -dx 2 ) and time reversal symmetry within electrodynamics. It turns out compatibility between these two is possible only if there is a singular physical event at the time of the singularity or if the topology is not trivial. In both cases the singularity takes on the appearance of a time-like mirror. We are able to demonstrate a relationship between the broken time symmetry in electrodynamics characterized by retarded radiation and radiation reaction and the absolute conformal time relative to the time of the singularity, i.e. between the Electromagnetic and Cosmological arrows of time. It is determined that the Wheeler-Feynman reasoning but with the future absorber replaced by the Cosmological mirror leads to a conflict with observation unless matter is strongly bound electromagnetically to the environment.
On the electrodynamics of spinning particles
International Nuclear Information System (INIS)
Holten, J.W. van
1990-01-01
The electrodynamics of spinning point particles is considered. A modification of the Lorentz force law is introduced which can be interpreted as a classical limit of the Dirac-Klein-Gordon equation. An improved version of the inhomogeneous Maxwell equations is constructed to describe the classical fields of spinning particles. Both classical and quantum electrodynamics are shown to predict relativistic time-dilatation effects for spinning particles in an electromagnetic field, even in the limit of zero velocity. The life-time of unstable charged particles moving in a Coulomb field is computed for both spin-zero and spin-half particles. Comparison shows spin effects to be present but relatively small. The magnitude of further spin-dependent correction from hyperfine interactions is computed. A measurement of the life-time of muons in atomic bound states separated by such spin-dependent hyperfine interactions would provide a clean test for the effect predicted. Similar effects are shown to arise in non-abelian gauge theories such as QCD. (author). 18 refs
Covariant electrodynamics in linear media: Optical metric
Thompson, Robert T.
2018-03-01
While the postulate of covariance of Maxwell's equations for all inertial observers led Einstein to special relativity, it was the further demand of general covariance—form invariance under general coordinate transformations, including between accelerating frames—that led to general relativity. Several lines of inquiry over the past two decades, notably the development of metamaterial-based transformation optics, has spurred a greater interest in the role of geometry and space-time covariance for electrodynamics in ponderable media. I develop a generally covariant, coordinate-free framework for electrodynamics in general dielectric media residing in curved background space-times. In particular, I derive a relation for the spatial medium parameters measured by an arbitrary timelike observer. In terms of those medium parameters I derive an explicit expression for the pseudo-Finslerian optical metric of birefringent media and show how it reduces to a pseudo-Riemannian optical metric for nonbirefringent media. This formulation provides a basis for a unified approach to ray and congruence tracing through media in curved space-times that may smoothly vary among positively refracting, negatively refracting, and vacuum.
Tethered Forth system for FPGA applications
Goździkowski, Paweł; Zabołotny, Wojciech M.
2013-10-01
This paper presents the tethered Forth system dedicated for testing and debugging of FPGA based electronic systems. Use of the Forth language allows to interactively develop and run complex testing or debugging routines. The solution is based on a small, 16-bit soft core CPU, used to implement the Forth Virtual Machine. Thanks to the use of the tethered Forth model it is possible to minimize usage of the internal RAM memory in the FPGA. The function of the intelligent terminal, which is an essential part of the tethered Forth system, may be fulfilled by the standard PC computer or by the smartphone. System is implemented in Python (the software for intelligent terminal), and in VHDL (the IP core for FPGA), so it can be easily ported to different hardware platforms. The connection between the terminal and FPGA may be established and disconnected many times without disturbing the state of the FPGA based system. The presented system has been verified in the hardware, and may be used as a tool for debugging, testing and even implementing of control algorithms for FPGA based systems.
Coat/Tether Interactions—Exception or Rule?
Schröter, Saskia; Beckmann, Sabrina; Schmitt, Hans Dieter
2016-01-01
Coat complexes are important for cargo selection and vesicle formation. Recent evidence suggests that they may also be involved in vesicle targeting. Tethering factors, which form an initial bridge between vesicles and the target membrane, may bind to coat complexes. In this review, we ask whether these coat/tether interactions share some common mechanisms, or whether they are special adaptations to the needs of very specific transport steps. We compare recent findings in two multisubunit tethering complexes, the Dsl1 complex and the HOPS complex, and put them into context with the TRAPP I complex as a prominent example for coat/tether interactions. We explore where coat/tether interactions are found, compare their function and structure, and comment on a possible evolution from a common ancestor of coats and tethers. PMID:27243008
Coat/Tether Interactions-Exception or Rule?
Schroeter, Saskia; Beckmann, Sabrina; Schmitt, Hans Dieter
2016-01-01
Coat complexes are important for cargo selection and vesicle formation. Recent evidence suggests that they may also be involved in vesicle targeting. Tethering factors, which form an initial bridge between vesicles and the target membrane, may bind to coat complexes. In this review, we ask whether these coat/tether interactions share some common mechanisms, or whether they are special adaptations to the needs of very specific transport steps. We compare recent findings in two multisubunit tethering complexes, the Dsl1 complex and the HOPS complex, and put them into context with the TRAPP I complex as a prominent example for coat/tether interactions. We explore where coat/tether interactions are found, compare their function and structure, and comment on a possible evolution from a common ancestor of coats and tethers.
Review of deployment technology for tethered satellite systems
Yu, B. S.; Wen, H.; Jin, D. P.
2018-03-01
Tethered satellite systems (TSSs) have attracted significant attention due to their potential and valuable applications for scientific research. With the development of various launched on-orbit missions, the deployment of tethers is considered a crucial technology for operation of a TSS. Both past orbiting experiments and numerical results have shown that oscillations of the deployed tether due to the Coriolis force and environmental perturbations are inevitable and that the impact between the space tether and end-body at the end of the deployment process leads to complicated nonlinear phenomena. Hence, a set of suitable control methods plays a fundamental role in tether deployment. This review article summarizes previous work on aspects of the dynamics, control, and ground-based experiments of tether deployment. The relevant basic principles, analytical expressions, simulation cases, and experimental results are presented as well.
Models of dynamic extraction of lipid tethers from cell membranes
International Nuclear Information System (INIS)
Nowak, Sarah A; Chou, Tom
2010-01-01
When a ligand that is bound to an integral membrane receptor is pulled, the membrane and the underlying cytoskeleton can deform before either the membrane delaminates from the cytoskeleton or the ligand detaches from the receptor. If the membrane delaminates from the cytoskeleton, it may be further extruded and form a membrane tether. We develop a phenomenological model for this process by assuming that deformations obey Hooke's law up to a critical force at which the cell membrane locally detaches from the cytoskeleton and a membrane tether forms. We compute the probability of tether formation and show that tethers can be extruded only within an intermediate range of force loading rates and pulling velocities. The mean tether length that arises at the moment of ligand detachment is computed as are the force loading rates and pulling velocities that yield the longest tethers
Coat/tether interactions – exceptions or rule?
Directory of Open Access Journals (Sweden)
Saskia eSchroeter
2016-05-01
Full Text Available Coat complexes are important for cargo selection and vesicle formation. Recent evidence suggests that they may also be involved in vesicle targeting. Tethering factors, which form an initial bridge between vesicles and the target membrane, may bind to coat complexes. In this review, we ask whether these coat/tether interactions share some common mechanisms, or whether they are special adaptations to the needs of very specific transport steps. We compare recent findings in two multisubunit tethering complexes, the Dsl1 complex and the HOPS complex, and put them into context with the TRAPP I complex as a prominent example for coat/tether interactions. We explore where coat/tether interactions are found, compare their function and structure, and comment on a possible evolution from a common ancestor of coats and tethers.
The stochastic dynamics of tethered microcantilevers in a viscous fluid
Energy Technology Data Exchange (ETDEWEB)
Robbins, Brian A.; Paul, Mark R. [Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Radiom, Milad; Ducker, William A. [Department of Chemical Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Walz, John Y. [Department of Chemical Engineering, University of Kentucky, Lexington, Kentucky 40506 (United States)
2014-10-28
We explore and quantify the coupled dynamics of a pair of micron scale cantilevers immersed in a viscous fluid that are also directly tethered to one another at their tips by a spring force. The spring force, for example, could represent the molecular stiffness or elasticity of a biomolecule or material tethered between the cantilevers. We use deterministic numerical simulations with the fluctuation-dissipation theorem to compute the stochastic dynamics of the cantilever pair for the conditions of experiment when driven only by Brownian motion. We validate our approach by comparing directly with experimental measurements in the absence of the tether which shows excellent agreement. Using numerical simulations, we quantify the correlated dynamics of the cantilever pair over a range of tether stiffness. Our results quantify the sensitivity of the auto- and cross-correlations of equilibrium fluctuations in cantilever displacement to the stiffness of the tether. We show that the tether affects the magnitude of the correlations which can be used in a measurement to probe the properties of an attached tethering substance. For the configurations of current interest using micron scale cantilevers in water, we show that the magnitude of the fluid coupling between the cantilevers is sufficiently small such that the influence of the tether can be significant. Our results show that the cross-correlation is more sensitive to tether stiffness than the auto-correlation indicating that a two-cantilever measurement has improved sensitivity when compared with a measurement using a single cantilever.
Parametric resonance in quantum electrodynamics vacuum birefringence
Arza, Ariel; Elias, Ricardo Gabriel
2018-05-01
Vacuum magnetic birefringence is one of the most interesting nonlinear phenomena in quantum electrodynamics because it is a pure photon-photon result of the theory and it directly signalizes the violation of the classical superposition principle of electromagnetic fields in the full quantum theory. We perform analytical and numerical calculations when an electromagnetic wave interacts with an oscillating external magnetic field. We find that in an ideal cavity, when the external field frequency is around the electromagnetic wave frequency, the normal and parallel components of the wave suffer parametric resonance at different rates, producing a vacuum birefringence effect growing in time. We also study the case where there is no cavity and the oscillating magnetic field is spatially localized in a region of length L . In both cases we find also a rotation of the elliptical axis.
The Earth's ionosphere plasma physics and electrodynamics
Kelley, Michael C
2007-01-01
Although interesting in its own right, due to the ever-increasing use of satellites for communication and navigation, weather in the ionosphere is of great concern. Every such system uses trans-ionospheric propagation of radio waves, waves which must traverse the commonly turbulent ionosphere. Understanding this turbulence and predicting it are one of the major goals of the National Space Weather program. Acquiring such a prediction capability will rest on understanding the very topics of this book, the plasma physics and electrodynamics of the system. Fully updated to reflect advances in the field in the 20 years since the first edition published Explores the buffeting of the ionosphere from above by the sun and from below by the lower atmosphere Unique text appropriate both as a reference and for coursework.
Plasma physics and fusion plasma electrodynamics
Bers, Abraham
2016-01-01
Plasma is a ubiquitous state of matter at high temperatures. The electrodynamics of plasmas encompasses a large number of applications, from understanding plasmas in space and the stars, to their use in processing semiconductors, and their role in controlled energy generation by nuclear fusion. This book covers collective and single particle dynamics of plasmas for fully ionized as well as partially ionized plasmas. Many aspects of plasma physics in current fusion energy generation research are addressed both in magnetic and inertial confinement plasmas. Linear and nonlinear dynamics in hydrodynamic and kinetic descriptions are offered, making both simple and complex aspects of the subject available in nearly every chapter. The approach of dividing the basic aspects of plasma physics as "linear, hydrodynamic descriptions" to be covered first because they are "easier", and postponing the "nonlinear and kinetic descriptions" for later because they are "difficult" is abandoned in this book. For teaching purpose...
Magnetized black holes and nonlinear electrodynamics
Kruglov, S. I.
2017-08-01
A new model of nonlinear electrodynamics with two parameters is proposed. We study the phenomenon of vacuum birefringence, the causality and unitarity in this model. There is no singularity of the electric field in the center of pointlike charges and the total electrostatic energy is finite. We obtain corrections to the Coulomb law at r →∞. The weak, dominant and strong energy conditions are investigated. Magnetized charged black hole is considered and we evaluate the mass, metric function and their asymptotic at r →∞ and r → 0. The magnetic mass of the black hole is calculated. The thermodynamic properties and thermal stability of regular black holes are discussed. We calculate the Hawking temperature of black holes and show that there are first-order and second-order phase transitions. The parameters of the model when the black hole is stable are found.
Dual-keel electrodynamic maglev system
Energy Technology Data Exchange (ETDEWEB)
Jianlang, He [Argonne National Lab., IL (United States); Rote, D M [Argonne National Lab., IL (United States); Zian, Wang [Argonne National Lab., IL (United States); Coffey, H T [Argonne National Lab., IL (United States)
1996-12-31
This paper introduces a new concept for an electrodynamic-suspension maglev system that has a dual-keel arrangement. Each keel consists of a row of superconducting magnets aboard the vehicle. The keels move in troughs in the guideway that are each lined with pairs of figure-eight-shaped null-flux coils. Each pair of null-flux coils is cross-connected to produce null-flux suspension and guidance force. The cross-connected figure-eight null-flux coils in each trough are also energized by a three-phase power supply to produce propulsive force. Preliminary analysis shows that the new system has many advantages over other EDS systems in terms of system performance and dynamic stability. (orig.)
Quantum quincunx in cavity quantum electrodynamics
International Nuclear Information System (INIS)
Sanders, Barry C.; Bartlett, Stephen D.; Tregenna, Ben; Knight, Peter L.
2003-01-01
We introduce the quantum quincunx, which physically demonstrates the quantum walk and is analogous to Galton's quincunx for demonstrating the random walk by employing gravity to draw pellets through pegs on a board, thereby yielding a binomial distribution of final peg locations. In contradistinction to the theoretical studies of quantum walks over orthogonal lattice states, we introduce quantum walks over nonorthogonal lattice states (specifically, coherent states on a circle) to demonstrate that the key features of a quantum walk are observable albeit for strict parameter ranges. A quantum quincunx may be realized with current cavity quantum electrodynamics capabilities, and precise control over decoherence in such experiments allows a remarkable decrease in the position noise, or spread, with increasing decoherence
In-Depth Development of Classical Electrodynamics
Directory of Open Access Journals (Sweden)
Keilman Y. N.
2008-01-01
Full Text Available There is hope that a properly developed Classical Electrodynamics (CED will be able to play a role in a unified field theory explaining electromagnetism, quantum phenomena, and gravitation. There is much work that has to be done in this direction. In this article we propose a move towards this aim by refining the basic principles of an improved CED. Attention is focused on the reinterpretation of the E-M potential. We use these basic principles to obtain solutions that explain the interactions between a constant electromagnetic field and a thin layer of material continuum; between a constant electromagnetic field and a spherical configuration of material continuum (for a charged elementary particle; between a transverse electromagnetic wave and a material continuum; between a longitudinal aether wave (dummy wave and a material continuum.
Quantum Electrodynamics in Photonic Crystal Waveguides
DEFF Research Database (Denmark)
Nielsen, Henri Thyrrestrup
In this thesis we have performed quantum electrodynamics (QED) experiments in photonic crystal (PhC) waveguides and cavity QED in the Anderson localized regime in disordered PhC waveguides. Decay rate measurements of quantum dots embedded in PhC waveguides has been used to map out the variations...... in the local density of states (LDOS) in PhC waveguides. From decay rate measurements on quantum dot lines temperature tuned in the vicinity of the waveguide band edge, a β-factor for a single quantum dot of more then 85% has been extracted. Finite difference time domain simulations (FDTD) for disordered Ph...... is shown to increase from 3 − 7 um for no intentional disorder to 25 um for 6% disorder. A distribution of losses is seen to be necessary to explain the measured Q-factor distributions. Finally we have performed a cavity QED experiment between single quantum dots and an Anderson localized mode, where a β...
Electrodynamic Dust Shield for Space Applications
Mackey, Paul J.; Johansen, Michael R.; Olsen, Robert C.; Raines, Matthew G.; Phillips, James R., III; Cox, Rachel E.; Hogue, Michael D.; Pollard, Jacob R. S.; Calle, Carlos I.
2016-01-01
Dust mitigation technology has been highlighted by NASA and the International Space Exploration Coordination Group (ISECG) as a Global Exploration Roadmap (GER) critical technology need in order to reduce life cycle cost and risk, and increase the probability of mission success. The Electrostatics and Surface Physics Lab in Swamp Works at the Kennedy Space Center has developed an Electrodynamic Dust Shield (EDS) to remove dust from multiple surfaces, including glass shields and thermal radiators. Further development is underway to improve the operation and reliability of the EDS as well as to perform material and component testing outside of the International Space Station (ISS) on the Materials on International Space Station Experiment (MISSE). This experiment is designed to verify that the EDS can withstand the harsh environment of space and will look to closely replicate the solar environment experienced on the Moon.
Maxwell electrodynamics subjected to quantum vacuum fluctuations
International Nuclear Information System (INIS)
Gevorkyan, A. S.; Gevorkyan, A. A.
2011-01-01
The propagation of electromagnetic waves in the vacuum is considered taking into account quantum fluctuations in the limits of Maxwell-Langevin (ML) equations. For a model of “white noise” fluctuations, using ML equations, a second order partial differential equation is found which describes the quantum distribution of virtual particles in vacuum. It is proved that in order to satisfy observed facts, the Lamb Shift etc, the virtual particles should be quantized in unperturbed vacuum. It is shown that the quantized virtual particles in toto (approximately 86 percent) are condensed on the “ground state” energy level. It is proved that the extension of Maxwell electrodynamics with inclusion of the vacuum quantum field fluctuations may be constructed on a 6D space-time continuum with a 2D compactified subspace. Their influence on the refraction indexes of vacuum is studied.
Stochastic Electrodynamics and the Compton effect
International Nuclear Information System (INIS)
Franca, H.M.; Barranco, A.V.
1987-12-01
Some of the main qualitative features of the Compton effect are tried to be described within the realm of Classical Stochastic Electrodynamics (SED). It is found indications that the combined action of the incident wave (frequency ω), the radiation reaction force and the zero point fluctuating electromagnetic fields of SED, are able to given a high average recoil velocity v/c=α/(1+α) to the charged particle. The estimate of the parameter α gives α ∼ ℎω/mc 2 where 2Πℎ is the constant and mc 2 is the rest energy of the particle. It is verified that this recoil is just that necessary to explain the frequency shift, observed in the scattered radiation as due to a classical double Doppler shift. The differential cross section for the radiation scattered by the recoiling charge using classical electromagnetism also calculated. The same expression as obtained by Compton in his fundamental work of 1923 is found. (author) [pt
Flux Modulation in the Electrodynamic Loudspeaker
DEFF Research Database (Denmark)
Halvorsen, Morten; Tinggaard, Carsten; Agerkvist, Finn T.
2015-01-01
This paper discusses the effect of flux modulation in the electrodynamic loudspeaker with main focus on the effect on the force factor. A measurement setup to measure the AC flux modulation with static voice coil is explained and the measurements shows good consistency with FEA simulations....... Measurements of the generated AC flux modulation shows, that eddy currents are the main source to magnetic losses in form of phase lag and amplitude changes. Use of a copper cap shows a decrease in flux modulation amplitude at the expense of increased power losses. Finally, simulations show...... that there is a high dependency between the generated AC flux modulation from the voice coil and the AC force factor change....
Gravitational waves and electrodynamics: new perspectives.
Cabral, Francisco; Lobo, Francisco S N
2017-01-01
Given the recent direct measurement of gravitational waves (GWs) by the LIGO-VIRGO collaboration, the coupling between electromagnetic fields and gravity have a special relevance since it opens new perspectives for future GW detectors and also potentially provides information on the physics of highly energetic GW sources. We explore such couplings using the field equations of electrodynamics on (pseudo) Riemann manifolds and apply it to the background of a GW, seen as a linear perturbation of Minkowski geometry. Electric and magnetic oscillations are induced that propagate as electromagnetic waves and contain information as regards the GW which generates them. The most relevant results are the presence of longitudinal modes and dynamical polarization patterns of electromagnetic radiation induced by GWs. These effects might be amplified using appropriate resonators, effectively improving the signal to noise ratio around a specific frequency. We also briefly address the generation of charge density fluctuations induced by GWs and the implications for astrophysics.
Higher order corrections in quantum electrodynamics
International Nuclear Information System (INIS)
Rafael, E.
1977-01-01
Theoretical contributions to high-order corrections in purely leptonic systems, such as electrons and muons, muonium (μ + e - ) and positronium (e + e - ), are reviewed to establish the validity of quantum electrodynamics (QED). Two types of QED contributions to the anomalous magnetic moments are considered, from diagrams with one fermion type lines and those witn two fermion type lines. The contributions up to eighth order are compared to the data available with a different accuracy. Good agreement is stated within the experimental errors. The experimental accuracy of the muonium hyperfine structure and of the radiative corrections to the decay of positronium are compared to the one attainable in theoretical calculations. The need for a higher precision in both experimental data and theoretical calculations is stated
Gravitational waves and electrodynamics: new perspectives
Energy Technology Data Exchange (ETDEWEB)
Cabral, Francisco; Lobo, Francisco S.N. [Faculdade de Ciencias da Universidade de Lisboa, Instituto de Astrofisica e Ciencias do Espaco, Lisbon (Portugal)
2017-04-15
Given the recent direct measurement of gravitational waves (GWs) by the LIGO-VIRGO collaboration, the coupling between electromagnetic fields and gravity have a special relevance since it opens new perspectives for future GW detectors and also potentially provides information on the physics of highly energetic GW sources. We explore such couplings using the field equations of electrodynamics on (pseudo) Riemann manifolds and apply it to the background of a GW, seen as a linear perturbation of Minkowski geometry. Electric and magnetic oscillations are induced that propagate as electromagnetic waves and contain information as regards the GW which generates them. The most relevant results are the presence of longitudinal modes and dynamical polarization patterns of electromagnetic radiation induced by GWs. These effects might be amplified using appropriate resonators, effectively improving the signal to noise ratio around a specific frequency. We also briefly address the generation of charge density fluctuations induced by GWs and the implications for astrophysics. (orig.)
Quantum electrodynamics in curved space-time
International Nuclear Information System (INIS)
Buchbinder, I.L.; Gitman, D.M.; Fradkin, E.S.
1981-01-01
The lagrangian of quantum electrodynamics in curved space-time is constructed and the interaction picture taking into account the external gravitational field exactly is introduced. The transform from the Heisenberg picture to the interaction picture is carried out in a manifestly covariant way. The properties of free spinor and electromagnetic quantum fields are discussed and conditions under which initial and final creation and annihilation operators are connected by unitarity transformation are indicated. The derivation of Feynman's rules for quantum processes are calculated on the base of generalized normal product of operators. The way of reduction formula derivations is indicated and the suitable Green's functions are introduced. A generating functional for this Green's function is defined and the system of functional equations for them is obtained. The representation of different generating funcationals by means of functional integrals is introduced. Some consequences of S-matrix unitary condition are considered which leads to the generalization of the optic theorem
Fluidic electrodynamics: Approach to electromagnetic propulsion
International Nuclear Information System (INIS)
Martins, Alexandre A.; Pinheiro, Mario J.
2009-01-01
We report on a new methodological approach to electrodynamics based on a fluidic viewpoint. We develop a systematic approach establishing analogies between physical magnitudes and isomorphism (structure-preserving mappings) between systems of equations. This methodological approach allows us to give a general expression for the hydromotive force, thus re-obtaining the Navier-Stokes equation departing from the appropriate electromotive force. From this ground we offer a fluidic approach to different kinds of issues with interest in propulsion, e.g., the force exerted by a charged particle on a body carrying current; the magnetic force between two parallel currents; the Magnus's force. It is shown how the intermingle between the fluid vector fields and electromagnetic fields leads to new insights on their dynamics. The new concepts introduced in this work suggest possible applications to electromagnetic (EM) propulsion devices and the mastery of the principles of producing electric fields of required configuration in plasma medium.
Electrodynamics as a theory of interacting complex charges
International Nuclear Information System (INIS)
Akeyo Omolo, Joseph
2003-04-01
In this paper, we formulate a general theory of electrodynamics which incorporates both electric and magnetic charges. The mathematical origin of a second vector potential and magnetic charge is established. Electrodynamics is then reformulated in complex form as a theory of complex charges moving in a complex force field. This provides the framework for complex charged particle interactions as a generalization of Schwinger's theory of dyon-dyon interactions. The concept of duality transformation relating electric and magnetic charge spaces is developed within the general framework of electrodynamics in complex form. (author)
Self-assembled tethered bimolecular lipid membranes.
Sinner, Eva-Kathrin; Ritz, Sandra; Naumann, Renate; Schiller, Stefan; Knoll, Wolfgang
2009-01-01
This chapter describes some of the strategies developed in our group for designing, constructing and structurally and functionally characterizing tethered bimolecular lipid membranes (tBLM). We introduce this platform as a novel model membrane system that complements the existing ones, for example, Langmuir monolayers, vesicular liposomal dispersions and bimolecular ("black") lipid membranes. Moreover, it offers the additional advantage of allowing for studies of the influence of membrane structure and order on the function of integral proteins, for example, on how the composition and organization of lipids in a mixed membrane influence the ion translocation activity of integral channel proteins. The first strategy that we introduce concerns the preparation of tethered monolayers by the self-assembly of telechelics. Their molecular architecture with a headgroup, a spacer unit (the "tether") and the amphiphile that mimics the lipid molecule allows them to bind specifically to the solid support thus forming the proximal layer of the final architecture. After fusion of vesicles that could contain reconstituted proteins from a liposomal dispersion in contact to this monolayer the tethered bimolecular lipid membrane is obtained. This can then be characterized by a broad range of surface analytical techniques, including surface plasmon spectroscopies, the quartz crystal microbalance, fluorescence and IR spectroscopies, and electrochemical techniques, to mention a few. It is shown that this concept allows for the construction of tethered lipid bilayers with outstanding electrical properties including resistivities in excess of 10 MOmega cm2. A modified strategy uses the assembly of peptides as spacers that couple covalently via their engineered sulfhydryl or lipoic acid groups at the N-terminus to the employed gold substrate, while their C-terminus is being activated afterward for the coupling of, for example, dimyristoylphosphatidylethanol amine (DMPE) lipid molecules
Space webs based on rotating tethered formations
Palmerini, Giovanni B.; Sgubini, Silvano; Sabatini, Marco
2009-07-01
Several on-going studies indicate the interest for large, light orbiting structures, shaped as fish nets or webs: along the ropes of the web small spacecraft can move like spiders to position and re-locate, at will, pieces of hardware devoted to specific missions. The concept could be considered as an intermediate solution between the large monolithic structure, heavy and expensive to realize, but easy to control, and the formations of satellites, where all system members are completely free and should manoeuvre in order to acquire a desired configuration. Instead, the advantage of having a "hard-but-light" link among the different grids lays in the partition of the tasks among system components and in a possible overall reduction of the control system complexity and cost. Unfortunately, there is no stable configuration for an orbiting, two-dimensional web made by light, flexible tethers which cannot support compression forces. A possible solution is to make use of centrifugal forces to pull the net, with a reduced number of simple thrusters located at the tips of the tethers to initially acquire the required spin. In this paper a dynamic analysis of a simplified rotating web is performed, in order to evaluate the spinning velocity able to satisfy the requirement for the stability of the system. The model adopted overlaps simpler elements, each of them given by a tether (made up of a number of linear finite elements) connecting two extreme bodies accommodating the spinning thrusters. The combination of these "diameter-like" elements provides the web, shaped according to the specific requirements. The net is primarily considered as subjected to Keplerian attraction and J2 and drag perturbations only, but its behaviour under thermal inputs is also investigated.
Nuclear pore complex tethers to the cytoskeleton.
Goldberg, Martin W
2017-08-01
The nuclear envelope is tethered to the cytoskeleton. The best known attachments of all elements of the cytoskeleton are via the so-called LINC complex. However, the nuclear pore complexes, which mediate the transport of soluble and membrane bound molecules, are also linked to the microtubule network, primarily via motor proteins (dynein and kinesins) which are linked, most importantly, to the cytoplasmic filament protein of the nuclear pore complex, Nup358, by the adaptor BicD2. The evidence for such linkages and possible roles in nuclear migration, cell cycle control, nuclear transport and cell architecture are discussed. Copyright © 2017. Published by Elsevier Ltd.
RF electrodynamics in small particles of oxides - a review
CSIR Research Space (South Africa)
Srinivasu, VV
2008-01-01
Full Text Available RF electrodynamics, particularly, the low field rf absorption in small superconducting and manganite particles is reviewed and compared with their respective bulk counterparts. Experimental and theoretical aspects of the small particle...
Mixed fermion-photon condensate in strongly coupled quantum electrodynamics
International Nuclear Information System (INIS)
Gusynin, V.P.; Kushnir, V.A.
1989-01-01
The existence of a new mixed fermion-photon condensate breaking chiral symmetry in strongly coupled phase of quantum electrodynamics is shown. An analytical expression for the renormalized condensate is obtained. 20 refs.; 2 figs
Quantum electrodynamic effects for light and heavy nuclei
International Nuclear Information System (INIS)
Anon.
1973-01-01
The autoionization of positrons and the problem of vacuum polarization are discussed within the framework of quantum field theory. Various possible heavy ion experiments to check on the nonlinearity of electrodynamics are described. (8 figures) (U.S.)
Lorentz-violating electrodynamics and the cosmic microwave background.
Kostelecký, V Alan; Mewes, Matthew
2007-07-06
Possible Lorentz-violating effects in the cosmic microwave background are studied. We provide a systematic classification of renormalizable and nonrenormalizable operators for Lorentz violation in electrodynamics and use polarimetric observations to search for the associated violations.
Dimensional renormalization and comparison of renormalization schemes in quantum electrodynamics
International Nuclear Information System (INIS)
Coquereaux, R.
1979-02-01
The method of dimensional renormalization as applied to quantum electrodynamics is discussed. A general method is given which allows one to compare the various quantities like coupling constants and masses that appear in different renormalization schemes
Climber Motion Optimization for the Tethered Space Elevator
Williams, P.; Ockels, W.J.
The tethered space elevator could provide a revolutionary means for enabling cheap transportation to geostationary altitude and beyond. Assuming that such a system can be built, one of the dynamic design problems is determining a means of moving the elevator along the tether so as to minimize the
Modeling and Simulation of a Tethered Harpoon for Comet Sampling
Quadrelli, Marco B.
2014-01-01
This paper describes the development of a dynamic model and simulation results of a tethered harpoon for comet sampling. This model and simulation was done in order to carry out an initial sensitivity analysis for key design parameters of the tethered system. The harpoon would contain a canister which would collect a sample of soil from a cometary surface. Both a spring ejected canister and a tethered canister are considered. To arrive in close proximity of the spacecraft at the end of its trajectory so it could be captured, the free-flying canister would need to be ejected at the right time and with the proper impulse, while the tethered canister must be recovered by properly retrieving the tether at a rate that would avoid an excessive amplitude of oscillatory behavior during the retrieval. The paper describes the model of the tether dynamics and harpoon penetration physics. The simulations indicate that, without the tether, the canister would still reach the spacecraft for collection, that the tether retrieval of the canister would be achievable with reasonable fuel consumption, and that the canister amplitude upon retrieval would be insensitive to variations in vertical velocity dispersion.
Attitude control analysis of tethered de-orbiting
Peters, T. V.; Briz Valero, José Francisco; Escorial Olmos, Diego; Lappas, V.; Jakowski, P.; Gray, I.; Tsourdos, A.; Schaub, H.; Biesbroek, R.
2018-05-01
The increase of satellites and rocket upper stages in low earth orbit (LEO) has also increased substantially the danger of collisions in space. Studies have shown that the problem will continue to grow unless a number of debris are removed every year. A typical active debris removal (ADR) mission scenario includes launching an active spacecraft (chaser) which will rendezvous with the inactive target (debris), capture the debris and eventually deorbit both satellites. Many concepts for the capture of the debris while keeping a connection via a tether, between the target and chaser have been investigated, including harpoons, nets, grapples and robotic arms. The paper provides an analysis on the attitude control behaviour for a tethered de-orbiting mission based on the ESA e.Deorbit reference mission, where Envisat is the debris target to be captured by a chaser using a net which is connected to the chaser with a tether. The paper provides novel insight on the feasibility of tethered de-orbiting for the various mission phases such as stabilization after capture, de-orbit burn (plus stabilization), stabilization during atmospheric pass, highlighting the importance of various critical mission parameters such as the tether material. It is shown that the selection of the appropriate tether material while using simple controllers can reduce the effort needed for tethered deorbiting and can safely control the attitude of the debris/chaser connected with a tether, without the danger of a collision.
Three-dimensional quantum electrodynamics as an effective interaction
International Nuclear Information System (INIS)
Abdalla, E.; Carvalho Filho, F.M. de
1995-10-01
We obtain a Quantum Electrodynamics in 2 + 1 dimensions by applying a Kaluza-Klein type method of dimensional reduction to Quantum Electrodynamics in 3 + 1 dimensions rendering the model more realistic to application in solid-state systems, invariant under translations in one direction. We show that the model obtained leads to an effective action exhibiting an interesting phase structure and that the generated Chern-Simons term survives only in the broken phase. (author). 20 refs
Probing nonlinear electrodynamics in slowly rotating spacetimes through neutrino astrophysics
Cuesta, Herman J. Mosquera; Lambiase, Gaetano; Pereira, Jonas P.
2017-01-01
Huge electromagnetic fields are known to be present during the late stages of the dynamics of supernovae. Thus, when dealing with electrodynamics in this context, the possibility may arise to probe nonlinear theories (generalizations of the Maxwellian electromagnetism). We firstly solve Einstein field equations minimally coupled to an arbitrary (current-free) nonlinear Lagrangian of electrodynamics (NLED) in the slow rotation regime $a\\ll M$ (black hole's mass), up to first order in $a/M$. We...
Tethered Contactless Mobile Nuclear Environment Monitoring Robot
International Nuclear Information System (INIS)
Choi, S. Y.; Lee, E. S.; Lee, Kun J.; Kim, Su H.; Rim, C. T.
2013-01-01
In fact, the nuclear environment monitoring is significantly crucial for early detection of NPP accident, radiological emergency, the estimation of radiation exposure to nearby residents as well as the long term radioactivity. In the UAE, the nuclear environment monitoring is, however, quite challenging because sampling locations are far from NPPs and the outdoor temperature and humidity are very high for NPP workers to collect soil, air, and water samples. Therefore, nuclear environment monitoring robots (Nubos) are strongly needed for the NPPs in the UAE. The Nubos can be remotely controlled to collect samples in extreme environment instead of NPP workers. Moreover, the Nubos can be unmanned ground vehicles (UGVs), unmanned aerial vehicles (UAVs) and unmanned marine vehicles (UMVs) to collect soil, air, and water samples, respectively. In this paper, the prototype development of UGV type Nubos using power cable for a long distance power delivery, called Tethered contactless mobile Nubo is introduced and validated by experiments. In this paper, the prototype development of Tethered Contactless Mobile (TeCoM) Nubo, which can be powered continuously within several km distance and avoid tangled cable, and the indoor test are finished. As further works, outdoor demonstration and a grand scale R and D proposal of practical Nubo will be proceeded
Tethered Contactless Mobile Nuclear Environment Monitoring Robot
Energy Technology Data Exchange (ETDEWEB)
Choi, S. Y.; Lee, E. S.; Lee, Kun J.; Kim, Su H.; Rim, C. T. [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)
2013-05-15
In fact, the nuclear environment monitoring is significantly crucial for early detection of NPP accident, radiological emergency, the estimation of radiation exposure to nearby residents as well as the long term radioactivity. In the UAE, the nuclear environment monitoring is, however, quite challenging because sampling locations are far from NPPs and the outdoor temperature and humidity are very high for NPP workers to collect soil, air, and water samples. Therefore, nuclear environment monitoring robots (Nubos) are strongly needed for the NPPs in the UAE. The Nubos can be remotely controlled to collect samples in extreme environment instead of NPP workers. Moreover, the Nubos can be unmanned ground vehicles (UGVs), unmanned aerial vehicles (UAVs) and unmanned marine vehicles (UMVs) to collect soil, air, and water samples, respectively. In this paper, the prototype development of UGV type Nubos using power cable for a long distance power delivery, called Tethered contactless mobile Nubo is introduced and validated by experiments. In this paper, the prototype development of Tethered Contactless Mobile (TeCoM) Nubo, which can be powered continuously within several km distance and avoid tangled cable, and the indoor test are finished. As further works, outdoor demonstration and a grand scale R and D proposal of practical Nubo will be proceeded.
Electrodynamics in Arbitrary Reference Frames and in Arbitrary Material Media
International Nuclear Information System (INIS)
Horzela, A.; Kapuscik, E.; Widomski, M.
1999-01-01
Full text: The investigation of electromagnetic phenomena in material media still belongs to the most difficult tasks of electrodynamics. Complexity and variability of material media practically exclude effective applications of methods and computational techniques elaborated in the framework of standard microscopic electrodynamics with classical vacuum as a ground state. In order to obtain satisfactorily exact descriptions of electromagnetic properties of complex material media one is enforced to use methods and approximations which are difficult to control. Moreover, they usually break covariance properties and the results obtained are valid in one reference frame which choice remains subjective and model dependent. Some time ago we have proposed a reformulation of Maxwell electrodynamics which opens new ways in study of electromagnetic processes in material media. The formalism gets rid of assumptions characteristic for vacuum electrodynamics only and it avoids the usage of constitutive relations as primary relations put on quantities needed for a complete description of an electromagnetic system. Fundamental properties of all electromagnetic quantities are their uniquely defined transformation rules and their analysis allows to determine the possible relations between them. Within such a scheme it is possible to introduce constitutive relations which do not have analogies in macroscopic classical electrodynamics. They may be used in description of microscopic electromagnetic processes in a different way than it is done in the framework of quantum electrodynamics. (author)
Assessing tether anchor labeling and usability in pickup trucks.
Klinich, Kathleen D; Manary, Miriam A; Malik, Laura A; Flannagan, Carol A; Jermakian, Jessica S
2018-04-03
The objective of this study was to investigate vehicle factors associated with child restraint tether use and misuse in pickup trucks and evaluate 4 labeling interventions designed to educate consumers on proper tether use. Volunteer testing was performed with 24 subjects and 4 different pickup trucks. Each subject performed 8 child restraint installations among the 4 pickups using 2 forward-facing restraints: a Britax Marathon G4.1 and an Evenflo Triumph. Vehicles were selected to represent 4 different implementations of tether anchors among pickups: plastic loop routers (Chevrolet Silverado), webbing routers (Ram), back wall anchors (Nissan Frontier), and webbing routers plus metal anchors (Toyota Tundra). Interventions included a diagram label, Quick Response (QR) Code linked to video instruction, coordinating text label, and contrasting text tag. Subjects used the child restraint tether in 93% of trials. However, tether use was completely correct in only 9% of trials. An installation was considered functional if the subject attached the tether to a tether anchor and had a tight installation (ignoring routing and head restraint position); 28% of subjects achieved a functional installation. The most common installation error was attaching the tether hook to the anchor/router directly behind the child restraint (near the top of the seatback) rather than placing the tether through the router and attaching it to the anchor in the adjacent seating position. The Nissan Frontier, with the anchor located on the back wall of the cab, had the highest rate of correct installations but also had the highest rate of attaching the tether to components other than the tether anchor (seat adjustor, child restraint storage hook, around head restraint). None of the labeling interventions had a significant effect on correct installation; not a single subject scanned the QR Code to access the video instruction. Subjects with the most successful installations spent extensive time
A Way to Revised Quantum Electrodynamics
Directory of Open Access Journals (Sweden)
Lehnert B.
2012-04-01
Full Text Available In conventional theoretical physics and its Standard Model the guiding principle is that the equations are symmetrical. This limitation leads to a number of difficulties, because it does not permit masses for leptons and quarks, the electron tends to “explode” un- der the action of its self-charge, a corresponding photon model has no spin, and such a model cannot account for the “needle radiation” proposed by Einstein and observed in the photoelectric e ff ect and in two-slit experiments. This paper summarizes a revised Lorentz and gauge invariant quantum electrodynamic theory based on a nonzero electric field divergence in the vacuum and characterized by linear intrinsic broken symmetry. It thus provides an alternative to the Higgs concept of nonlinear spontaneous broken sym- metry, for solving the difficulties of the Standard Model. New results are obtained, such as nonzero and finite lepton rest masses, a point-charge-like behavior of the electron due to a revised renormalization procedure, a magnetic volume force which counteracts the electrostatic eigen-force of the electron, a nonzero spin of the photon and of light beams, needle radiation, and an improved understanding of the photoelectric effect, two-slit ex- periments, electron-positron pair formation, and cork-screw-shaped light beams.
Quantum electrodynamics with the spear magnetic detector
International Nuclear Information System (INIS)
Zipse, J.E.
1975-09-01
One makes a study of quantum electrodynamic processes which are present at the SPEAR colliding beam magnetic detector. We begin by describing the experiment performed by the SLAC-LBL collaboration and the results concerning the strong interaction. Then the interactions e + e - → e + e - and e + e - → μ + μ - are considered along with their third-order radiative corrections. These events, previously used to determine new limits for cutoff parameters in QED breakdown models, are further studied to show that the full distribution in coplanarity angle fits the theoretical prediction well. The major focus is on the fourth order two-photon process, e + e - → e + e - A + A - , which only recently has been realized to be significant in such experiments. Cross sections are derived and calculated exactly for this process and the results compared to a Weizacker-Williams equivalent photon calculation. The two-photon data are then isolated and fit to the calculation. A special experiment was done where the small-angle scattered electron or positron is ''tagged'' along with particles in the main detector. Cross sections and coplanarity distributions are measured and compared to calculation. Through these studies, one feels confident that one understand the nature of the two-photon process in the detector. One further explores the hadronic physics of the two-photon process, e + e - → e + e - hadrons, measuring pion cross sections, searching for resonances, and discussing future experiments
Fundamental tests in Cavity Quantum Electrodynamics
CERN. Geneva
2010-01-01
At the dawn of quantum physics, Einstein and Bohr had the dream to confine a photon in a box and to use this contraption in order to illustrate the strange laws of the quantum world. Cavity Quantum Electrodynamics has now made this dream real, allowing us to actually achieve in the laboratory variants of the thought experiments of the founding fathers of quantum theory. In our work at Ecole Normale Supérieure, we use a beam of Rydberg atoms to manipulate and probe non-destructively microwave photons trapped in a very high Q superconducting cavity. We realize ideal quantum non-demolition (QND) measurements of photon numbers, observe the radiation quantum jumps due to cavity relaxation and prepare non-classical fields such as Fock and Schrödinger cat states. Combining QND photon counting with a homodyne mixing method, we reconstruct the Wigner functions of these non-classical states and, by taking snapshots of these functions at increasing times, obtain movies of the decoherence process. These experiments ope...
Pole-factorization theorem in quantum electrodynamics
International Nuclear Information System (INIS)
Stapp, H.P.
1996-01-01
In quantum electrodynamics a classical part of the S-matrix is normally factored out in order to obtain a quantum remainder that can be treated perturbatively without the occurrence of infrared divergences. However, this separation, as usually performed, introduces spurious large-distance effects that produce an apparent breakdown of the important correspondence between stable particles and poles of the S-matrix, and, consequently, lead to apparent violations of the correspondence principle and to incorrect results for computations in the mesoscopic domain lying between the atomic and classical regimes. An improved computational technique is described that allows valid results to be obtained in this domain, and that leads, for the quantum remainder, in the cases studied, to a physical-region singularity structure that, as regards the most singular parts, is the same as the normal physical-region analytic structure in theories in which all particles have non-zero mass. The key innovations here are to define the classical part in coordinate space, rather than in momentum space, and to define there a separation of the photon-electron coupling into its classical and quantum parts that has the following properties: (1) The contributions from the terms containing only classical couplings can be summed to all orders to give a unitary operator that generates the coherent state that corresponds to the appropriate classical process, and (2) The quantum remainder can be rigorously shown to exhibit, as regards its most singular parts, the normal analytic structure. 22 refs
Circuit quantum electrodynamics with a spin qubit.
Petersson, K D; McFaul, L W; Schroer, M D; Jung, M; Taylor, J M; Houck, A A; Petta, J R
2012-10-18
Electron spins trapped in quantum dots have been proposed as basic building blocks of a future quantum processor. Although fast, 180-picosecond, two-quantum-bit (two-qubit) operations can be realized using nearest-neighbour exchange coupling, a scalable, spin-based quantum computing architecture will almost certainly require long-range qubit interactions. Circuit quantum electrodynamics (cQED) allows spatially separated superconducting qubits to interact via a superconducting microwave cavity that acts as a 'quantum bus', making possible two-qubit entanglement and the implementation of simple quantum algorithms. Here we combine the cQED architecture with spin qubits by coupling an indium arsenide nanowire double quantum dot to a superconducting cavity. The architecture allows us to achieve a charge-cavity coupling rate of about 30 megahertz, consistent with coupling rates obtained in gallium arsenide quantum dots. Furthermore, the strong spin-orbit interaction of indium arsenide allows us to drive spin rotations electrically with a local gate electrode, and the charge-cavity interaction provides a measurement of the resulting spin dynamics. Our results demonstrate how the cQED architecture can be used as a sensitive probe of single-spin physics and that a spin-cavity coupling rate of about one megahertz is feasible, presenting the possibility of long-range spin coupling via superconducting microwave cavities.
Directory of Open Access Journals (Sweden)
Alessandro Moura Zagatto
Full Text Available The purpose of the current study was to investigate the relationship between alternative anaerobic capacity method (MAODALT and a 30-s all-out tethered running test. Fourteen male recreational endurance runners underwent a graded exercise test, a supramaximal exhaustive effort and a 30-s all-out test on different days, interspaced by 48h. After verification of data normality (Shapiro-Wilk test, the Pearson's correlation test was used to verify the association between the anaerobic estimates from the MAODALT and the 30-s all-out tethered running outputs. Absolute MAODALT was correlated with mean power (r = 0.58; P = 0.03, total work (r = 0.57; P = 0.03, and mean force (r = 0.79; P = 0.001. In addition, energy from the glycolytic pathway (E[La-] was correlated with mean power (r = 0.58; P = 0.03. Significant correlations were also found at each 5s interval between absolute MAODALT and force values (r between 0.75 and 0.84, and between force values and E[La-] (r between 0.73 to 0.80. In conclusion, the associations between absolute MAODALT and the mechanical outputs from the 30-s all-out tethered running test evidenced the importance of the anaerobic capacity for maintaining force during the course of time in short efforts.
Fluid-membrane tethers: minimal surfaces and elastic boundary layers.
Powers, Thomas R; Huber, Greg; Goldstein, Raymond E
2002-04-01
Thin cylindrical tethers are common lipid bilayer membrane structures, arising in situations ranging from micromanipulation experiments on artificial vesicles to the dynamic structure of the Golgi apparatus. We study the shape and formation of a tether in terms of the classical soap-film problem, which is applied to the case of a membrane disk under tension subject to a point force. A tether forms from the elastic boundary layer near the point of application of the force, for sufficiently large displacement. Analytic results for various aspects of the membrane shape are given.
Resonator quantum electrodynamics on a microtrap chip
International Nuclear Information System (INIS)
Steinmetz, Tilo
2008-01-01
In the present dissertation experiments on resonator quantum electrodynamics on a microtrap chip are described. Thereby for the first time single atoms catched in a chip trap could be detected. For this in the framework of this thesis a novel optical microresonator was developed, which can because of its miniaturization be combined with the microtrap technique introduced in our working group for the manipulation of ultracold atoms. For this resonator glass-fiber ends are used as mirror substrates, between which a standing light wave is formed. With such a fiber Fabry-Perot resonator we obtain a finess of up to ∼37,000. Because of the small mode volumina in spite of moderate resonator quality the coherent interaction between an atom and a photon can be made so large that the regime of the strong atom-resonator coupling is reached. For the one-atom-one-photon coupling rate and the one-atom-one-photon cooperativity thereby record values of g 0 =2π.300 MHz respectively C 0 =210 are reached. Just so for the first time the strong coupling regime between a Bose-Einstein condensate (BEC) and the field of a high-quality resonator could be reached. The BEC was thereby by means of the magnetic microtrap potentials deterministically brought to a position within the resonator and totally transformed in a well defined antinode of an additionally optical standing-wave trap. The spectrum of the coupled atom-resonator system was measured for different atomic numbers and atom-resonator detunings, whereby a collective vacuum Rabi splitting of more than 20 GHz could be reached. [de
Structure an dynamics in cavity quantum electrodynamics
International Nuclear Information System (INIS)
Kimble, H.J.
1994-01-01
Much of the theoretical background related to the radiative processes for atoms in the presence of boundaries comes from two often disjoint areas, namely cavity quantum electrodynamics and optical bistability with two-state atoms. While the former of these areas has been associated to a large degree with studies in a perturbative domain of altered associated to a large degree with studies in a perturbative domain of altered emission processes in the presence of boundaries other than those of free space, the latter is often viewed from the perspective of hysteresis cycles and device applications. With the exception of the laser, however, perhaps the most extensive investigations of quantum statistical processes in quantum optics are to be found in the literature on bistability with two-state atoms and on cavity QED. Unfortunately, the degree of overlap of these two areas has not always been fully appreciated. This circumstance is perhaps due in part to the fact that the investigation of dynamical processes in cavity QED has had as its cornerstone the Jaynes-Cummings problem, with extensions to include, for example, small amounts of dissipation. On the other hand, a principle aspect of the bistability literature has been the study of quantum fluctuations in open systems for which dissipation plays a central role, but for which the coherent quantum dynamics of the Haynes-Cummings model are to a large measure lost due to the usual assumption of large system size and weak coupling (as in the standard theory of the laser). 132 refs., 26 figs., 1 tab
Nonrelativistic quantum electrodynamic approach to photoemission theory
International Nuclear Information System (INIS)
Fujikawa, Takashi; Arai, Hiroko
2005-01-01
A new nonrelativistic many-body theory to analyze X-ray photoelectron spectroscopy (XPS) spectra has been developed on the basis of quantum electrodynamic (QED) Keldysh Green's function approach. To obtain XPS current density we calculate electron Green's function g which partly includes electron-photon interactions. We first separate longitudinal and transverse parts of these Green's functions in the Coulomb gauge. The transverse electron selfenergy describes the electron-photon interaction, whereas the longitudinal electron selfenergy describes the electron-electron interaction. We derive the QED Hedin's equation from which we obtain systematic skeleton expansion in the power series of the screened Coulomb interaction W and the photon Green's function D kl . We show the present theory provides a sound theoretical tool to study complicated many-body processes such as the electron propagation damping, intrinsic, extrinsic losses and their interference, and furthermore, resonant photoemission processes. We have also found the importance of the mixed photon Green's functions D 0k and D k0 which have been supposed to be unimportant for the XPS analyses. They, however, directly describe the radiation field screening. In this work, photon field screening effects are discussed in one-step theory, where the electron-photon interaction operator Δ is proved to be replaced by ε -1 Δ beyond linear approximation. Beyond free photon Green's function approximation, photon scatterings from the electron density are incorporated within the present QED theory. These photon field effects can directly describe the microscopic photon field spatial variation specific to near the surface region and nanoparticle systems
Introduction to electrodynamics for microwave linear accelerators
International Nuclear Information System (INIS)
Whittum, D.H.
1998-04-01
This collection of notes and exercises is intended as a workbook to introduce the principles of microwave linear accelerators, starting with the underlying foundation in electrodynamics. The author reviewed Maxwell's equations, the Lorentz force law, and the behavior of fields near a conducting boundary. The author goes on to develop the principles of microwave electronics, including waveguide modes, circuit equivalence, shunt admittance of an iris, and voltage standing-wave ratio. The author constructed an elementary example of a waveguide coupled to a cavity, and examined its behavior during transient filling of the cavity, and in steady-state. He goes on to examine a periodic line. Then he examined the problem of acceleration in detail, studying first the properties of a single cavity-waveguide-beam system and developing the notions of wall Q, external Q, /Q shunt impedance, and transformer ratio. He then examined the behavior of such a system on and off resonance, on the bench, and under conditions of transient and steady-state beam-loading. This work provides the foundation for the commonly employed circuit equivalents and the basic scalings for such systems. Following this he examined the coupling of two cavities, powered by a single feed, and goes on to consider structures constructed from multiple coupled cavities. The basic scalings for constant impedance and constant gradient traveling-wave structures are set down, including features of steady-state beam-loading, and the coupled-circuit model. Effects of uniform and random detuning are derived. These notes conclude with a brief outline of some problems of current interest in accelerator research
Stationary Tether Device for Buoy Apparatus and System for Using
National Oceanic and Atmospheric Administration, Department of Commerce — A rigid, neutrally buoyant hydrodynamicaly-faired tether and associated fastening hardware that loosely holds a bathymetric float at a predetermined distance from a...
Hierarchical Structure in Semicrystalline Polymers Tethered to Nanospheres
Kim, Sung A; Archer, Lynden A.
2014-01-01
We report on structural and dynamic transitions of polymers tethered to nanoparticles. In particular, we use X-ray diffraction, vibrational spectroscopy, and thermal measurements to investigate multiscale structure and dynamic transitions of poly
Crowded, Confined, and Frustrated: Dynamics of Molecules Tethered to Nanoparticles
Agarwal, Praveen; Kim, Sung A.; Archer, Lynden A.
2012-01-01
Above a critical chemistry-dependent molecular weight, all polymer molecules entangle and, as a result, exhibit slow dynamics, enhanced viscosity, and elasticity. Herein we report on the dynamics of low molecular weight polymers tethered
FCAPD Protective Coating for Space Tethers, Phase I
National Aeronautics and Space Administration — Alameda Applied Sciences Corporation (AASC) proposes to demonstrate extended service lifetime of space tethers in the Low Earth Orbit (LEO) environment by using...
Relaxation Dynamics of Nanoparticle-Tethered Polymer Chains
Kim, Sung A; Mangal, Rahul; Archer, Lynden A.
2015-01-01
© 2015 American Chemical Society. Relaxation dynamics of nanoparticle-tethered cis-1,4-polyisoprene (PI) are investigated using dielectric spectroscopy and rheometry. A model system composed of polymer chains densely grafted to spherical SiO2
Tethered Nanoparticle–Polymer Composites: Phase Stability and Curvature
Srivastava, Samanvaya; Agarwal, Praveen; Archer, Lynden A.
2012-01-01
different small-angle X-ray scattering signatures in comparison to phase-separated composites comprised of bare or sparsely grafted nanoparticles. A general diagram for the dispersion state and phase stability of polymer tethered nanoparticle-polymer
Fiber Optic Shape Sensing for Tethered Marsupial Rovers, Phase II
National Aeronautics and Space Administration — Building upon the successful proof of concept work in Phase I, Luna Innovations Incorporated is proposing to design, build, and test a sensing tether for marsupial...
Topological vortices in generalized Born-Infeld-Higgs electrodynamics
International Nuclear Information System (INIS)
Casana, R.; Hora, E. da; Rubiera-Garcia, D.; Santos, C. dos
2015-01-01
A consistent BPS formalism to study the existence of topological axially symmetric vortices in generalized versions of the Born-Infeld-Higgs electrodynamics is implemented. Such a generalization modifies the field dynamics via the introduction of three nonnegative functions depending only in the Higgs field, namely,G(vertical stroke φ vertical stroke), w(vertical stroke φ vertical stroke), and V (vertical stroke φ vertical stroke). A set of first-order differential equations is attained when these functions satisfy a constraint related to the Ampere law. Such a constraint allows one to minimize the system's energy in such way that it becomes proportional to the magnetic flux. Our results provides an enhancement of the role of topological vortex solutions in Born-Infeld-Higgs electrodynamics. Finally, we analyze a set of models entailing the recovery of a generalized version of Maxwell-Higgs electrodynamics in a certain limit of the theory. (orig.)
Lumbosacral arachnoid cyst with tethered cord: A rare case report
Directory of Open Access Journals (Sweden)
S K Jain
2012-01-01
Full Text Available Arachnoid cysts are cerebrospinal fluid collections in the spine that can present with neurological symptoms or be discovered accidentally. Intradural location of such cysts especially in the lumbosacral region is relatively rare. The association of such cysts with other congenital anomalies such as tethered cord lends evidence to the developmental origin of arachnoid cysts. We report a case of lumbosacral arachnoid cyst with tethered cord in a 6-year-old male child and discuss the etiopathogenesis and management options.
Tethered catalysts for the hydration of carbon dioxide
Valdez, Carlos A; Satcher, Jr., Joe H; Aines, Roger D; Wong, Sergio E; Baker, Sarah E; Lightstone, Felice C; Stolaroff, Joshuah K
2014-11-04
A system is provided that substantially increases the efficiency of CO.sub.2 capture and removal by positioning a catalyst within an optimal distance from the air-liquid interface. The catalyst is positioned within the layer determined to be the highest concentration of carbon dioxide. A hydrophobic tether is attached to the catalyst and the hydrophobic tether modulates the position of the catalyst within the liquid layer containing the highest concentration of carbon dioxide.
Calculation of Flexible Bus-Bars Electrodynamic Stability with Application of Implicit Scheme
Directory of Open Access Journals (Sweden)
Y. G. Panamarenka
2008-01-01
Full Text Available A numerical method for calculation of open-air substations’ flexible bus-bars dynamic at short-circuit has been improved on equations of a flexible elastic string with application of an implicit scheme. On the basis of the numerical method a computer program FLEBUS for calculation of substations’ flexible bus-bars dynamic at short-circuit has been developed. An approbation and an estimation of calculation result reliability have been carried out in accordance with the program while using experimental data. On the basis of the obtained information it is possible to assert that the developed program is an independent tool for calculation of electrodynamic stability of substations’ flexible bus-bars.
On the Emergence of the Coulomb Forces in Quantum Electrodynamics
Directory of Open Access Journals (Sweden)
Jan Naudts
2017-01-01
Full Text Available A simple transformation of field variables eliminates Coulomb forces from the theory of quantum electrodynamics. This suggests that Coulomb forces may be an emergent phenomenon rather than being fundamental. This possibility is investigated in the context of reducible quantum electrodynamics. It is shown that states exist which bind free photon and free electron fields. The binding energy peaks in the long-wavelength limit. This makes it plausible that Coulomb forces result from the interaction of the electron/positron field with long-wavelength transversely polarized photons.
Quantum electrodynamics with 1D arti cial atoms
DEFF Research Database (Denmark)
Javadi, Alisa
A 1D atom, a single quantum emitter coupled to a single optical mode, exhibits rich quantum electrodynamic (QED) e_ects and is thought to be the key ingredient for many applications in quantuminformation processing. Single quantum dots (QD) in photonic-crystal waveguides (PCW) constitute a robust...... as expected from the theory. The value of g(2)(0) is around 1.08. The results con_rm the observation of an on-chip giant optical nonlinearity and the 1D atom behavior. Another direction in this thesis has been to investigate the e_ect of Anderson localization on the electrodynamics of QDs in PCWs. A large...
Gauge equivalence of the electrodynamics of charged bosons
International Nuclear Information System (INIS)
Sohn, R.; Haller, K.
1977-01-01
The quantum electrodynamics of charged scalar and vector bosons is formulated in the Lorentz gauge, and the effect of the charged particle--photon interaction on the subsidiary condition is explicitly taken into account. The results are extensions of earlier work on spinor quantum electrodynamics, but the presence of seagull vertices and anomalous current commutators in the case of the charged bosons make the extensions nontrivial. An operator gauge transformation that encompasses equations of motion as well as the commutator algebra of the field operators is developed; it is used to transform the theory from the Lorentz gauge to the Coulomb gauge
Wilson Fermions and Axion Electrodynamics in Optical Lattices
International Nuclear Information System (INIS)
Bermudez, A.; Martin-Delgado, M. A.; Mazza, L.; Rizzi, M.; Goldman, N.; Lewenstein, M.
2010-01-01
We show that ultracold Fermi gases in optical superlattices can be used as quantum simulators of relativistic lattice fermions in 3+1 dimensions. By exploiting laser-assisted tunneling, we find an analogue of the so-called naive Dirac fermions, and thus provide a realization of the fermion doubling problem. Moreover, we show how to implement Wilson fermions, and discuss how their mass can be inverted by tuning the laser intensities. In this regime, our atomic gas corresponds to a phase of matter where Maxwell electrodynamics is replaced by axion electrodynamics: a 3D topological insulator.
Electrodynamic forces and plasma conductivity inside the current sheet
International Nuclear Information System (INIS)
Bogdanov, S.Yu.; Frank, A.G.; Markov, V.S.
1985-01-01
The process of accumulation and explosive release of magnetic energy was studied in a current sheet of plasma of a high-current linear discharge. The distribution of current density and of electrodynamic forces were measured and the time evolution of these quantities was determined. The evolution of the plasma conductivity was also obtained. The measured and calculated electrodynamic forces may explain the plasma acceleration up to the velocities about 3x10 4 m/s only near the sheet edges. (D.Gy.)
Optical-lattice Hamiltonians for relativistic quantum electrodynamics
International Nuclear Information System (INIS)
Kapit, Eliot; Mueller, Erich
2011-01-01
We show how interpenetrating optical lattices containing Bose-Fermi mixtures can be constructed to emulate the thermodynamics of quantum electrodynamics (QED). We present models of neutral atoms on lattices in 1+1, 2+1, and 3+1 dimensions whose low-energy effective action reduces to that of photons coupled to Dirac fermions of the corresponding dimensionality. We give special attention to (2+1)-dimensional quantum electrodynamics (QED3) and discuss how two of its most interesting features, chiral symmetry breaking and Chern-Simons physics, could be observed experimentally.
Refractive index in generalized superconductors with Born-Infeld electrodynamics
Cheng, Jun; Pan, Qiyuan; Yu, Hongwei; Jing, Jiliang
2018-03-01
We investigate, in the probe limit, the negative refraction in the generalized superconductors with the Born-Infeld electrodynamics. We observe that the system has a negative Depine-Lakhtakia index in the superconducting phase at small frequencies and the greater the Born-Infeld corrections the larger the range of frequencies or the range of temperatures for which the negative refraction occurs. Furthermore, we find that the tunable Born-Infeld parameter can be used to improve the propagation of light in the holographic setup. Our analysis indicates that the Born-Infeld electrodynamics plays an important role in determining the optical properties of the boundary theory.
Time-dependent Kohn-Sham approach to quantum electrodynamics
International Nuclear Information System (INIS)
Ruggenthaler, M.; Mackenroth, F.; Bauer, D.
2011-01-01
We prove a generalization of the van Leeuwen theorem toward quantum electrodynamics, providing the formal foundations of a time-dependent Kohn-Sham construction for coupled quantized matter and electromagnetic fields. We circumvent the symmetry-causality problems associated with the action-functional approach to Kohn-Sham systems. We show that the effective external four-potential and four-current of the Kohn-Sham system are uniquely defined and that the effective four-current takes a very simple form. Further we rederive the Runge-Gross theorem for quantum electrodynamics.
Engineering squeezed states of microwave radiation with circuit quantum electrodynamics
International Nuclear Information System (INIS)
Li Pengbo; Li Fuli
2011-01-01
We introduce a squeezed state source for microwave radiation with tunable parameters in circuit quantum electrodynamics. We show that when a superconducting artificial multilevel atom interacting with a transmission line resonator is suitably driven by external classical fields, two-mode squeezed states of the cavity modes can be engineered in a controllable fashion from the vacuum state via adiabatic following of the ground state of the system. This scheme appears to be robust against decoherence and is realizable with present techniques in circuit quantum electrodynamics.
Flowing Plasma Interaction with an Electric Sail Tether Element
Schneider, Todd; Vaughn, Jason; Wright, Kenneth; Anderson, Allen; Stone, Nobie
2017-01-01
Harnessing the power of the solar wind, an Electric Sail, or E-sail, is a relatively new concept that promises to deliver high speed propellant-less propulsion. The electric sail is an invention made in 2006 at the Kumpula Space Centre in Finland by Pekka Janhunen [Janhunen and Sandroos, 2007]. At its core, an electric sail utilizes multiple positively biased tethers which exchange momentum with solar wind protons via the repelling electric field established around each tether, in other words, by reflecting the solar wind protons. Recognizing the solar wind is a plasma, the effective repelling area of each tether is increased significantly by the formation a plasma sheath around each tether. Fig. 1 shows schematically a spacecraft employing an electric sail. The positive voltage bias (greater than10kV) applied to each tether naturally results in electron collection. Therefore, the electric sail concept necessarily includes an electron source (electron gun) to return collected electrons to space and maintain the positive bias of the tether system.
DNA Electrochemistry with Tethered Methylene Blue
Pheeney, Catrina G.
2012-01-01
Methylene blue (MB′), covalently attached to DNA through a flexible C12 alkyl linker, provides a sensitive redox reporter in DNA electrochemistry measurements. Tethered, intercalated MB′ is reduced through DNA-mediated charge transport; the incorporation of a single base mismatch at position 3, 10, or 14 of a 17-mer causes an attenuation of the signal to 62 ± 3% of the well-matched DNA, irrespective of position in the duplex. The redox signal intensity for MB′–DNA is found to be least 3-fold larger than that of Nile blue (NB)–DNA, indicating that MB′ is even more strongly coupled to the π-stack. The signal attenuation due to an intervening mismatch does, however, depend on DNA film density and the backfilling agent used to passivate the surface. These results highlight two mechanisms for reduction of MB′ on the DNA-modified electrode: reduction mediated by the DNA base pair stack and direct surface reduction of MB′ at the electrode. These two mechanisms are distinguished by their rates of electron transfer that differ by 20-fold. The extent of direct reduction at the surface can be controlled by assembly and buffer conditions. PMID:22512327
Wall thickness tests by means of rotating electrodynamic transducers
International Nuclear Information System (INIS)
Hueschelrath, G.
1986-01-01
For about three years, the EROT system has been employed for measuring wall thicknesses on pipes of ferritic steels. The experience gathered and the degree of reliability reached up to now are definitely encouraging, so that an increased use of electrodynamic transducers can be expected for measuring pipes with outside diameters of up to 22 inches. (orig.) [de
On the New Symmetries in Electrodynamics and Quantum Theory
Kotel'nikov, G. A.
2004-01-01
The generalized definition of symmetry is formulated. Application of this definition for symmetric analysis of theoretical physics equations is considered. The version of electrodynamics is constructed permitting the faster-than-light motions of particles with real masses. Some elements of physical interpretation of the proposed theory are presented.
Causal approach to (2+1)-dimensional Quantum Electrodynamics
International Nuclear Information System (INIS)
Scharf, G.; Wreszinski, W.F.; Pimentel, B.M.; Tomazelli, J.L.
1993-05-01
It is shown that the causal approach to (2+1)-dimensional quantum electrodynamics yields a well-defined perturbative theory. In particular, and in contrast to renormalized perturbative quantum field theory, it is free of any ambiguities and ascribes a nonzero value to the dynamically generated, nonperturbative photon mass. (author). 12 refs
Infrared phenomena in quantum electrodynamics : II. Bremsstrahlung and compton scattering
Haeringen, W. van
The infrared aspects of quantum electrodynamics are discussed by treating two examples of scattering processes, bremsstrahlung and Compton scattering. As in the previous paper one uses a non-covariant diagram technique which gives very clear insight in the cancelling of infrared divergences between
Free-space quantum electrodynamics with a single Rydberg superatom
DEFF Research Database (Denmark)
Paris-Mandoki, Asaf; Braun, Christoph; Kumlin, Jan
2017-01-01
The interaction of a single photon with an individual two-level system is the textbook example of quantum electrodynamics. Achieving strong coupling in this system has so far required confinement of the light field inside resonators or waveguides. Here, we demonstrate strong coherent coupling...
Generalized noise terms for the quantized fluctuational electrodynamics
DEFF Research Database (Denmark)
Partanen, Mikko; Hayrynen, Teppo; Tulkki, Jukka
2017-01-01
position-dependent quantum models for the photon number in resonant structures have only been formulated very recently and only for dielectric media. Here we present a general position-dependent quantized fluctuational electrodynamics (QFED) formalism that extends the consistent field quantization...
Development of superconducting magnets for the Canadian electrodynamic Maglev vehicle
International Nuclear Information System (INIS)
Fife, A.A.; Ensing, H.J.; Tillotson, M.; Westera, W.
1986-01-01
A review is presented on the current status of superconducting magnet developments for the Canadian electrodynamic Maglev transportation system. Various design aspects of the levitation and linear synchronous motor magnets, appropriate for the current vehicle concepts, are discussed. In addition, recent experimental work is outlined on the development of a suitable epoxy impregnation technology for the superconducting coils
Charge-field formulation of quantum electrodynamics (QEMED)
International Nuclear Information System (INIS)
Leiter, D.
1980-01-01
By expressing classical electron theory in terms of 'charge-field' functional structures, it is shown that a finite formulation of the classical electrodynamics of point charges emerges in a simple and elegant fashion. This is used to construct a 'charge-field' quantum electrodynamic theory. It is found that interacting photon states are generated as a secondary manifestation of electron-positron quantization, and do not require the usual 'free' canonical quantization scheme. The possibility is discussed that this approach may lead to a better formulation of quantum electrodynamics in the Heisenberg picture and suggests a crucial experimental test to distinguish this new 'charge-field' quantum electrodynamics 'QEMED' from the standard QED formulation. Specifically QEMED predicts that the 'Einstein principle of separability' should be found to be valid for correlated photon polarization measurements, in which the polarizers are changed more rapidly than a characteristic photon travel time. Such an experiment (Aspect 1976) can distinguish between QEMED and QED in a complete and clear-cut fashion. (U.K.)
Electrodynamics, Differential Forms and the Method of Images
Low, Robert J.
2011-01-01
This paper gives a brief description of how Maxwell's equations are expressed in the language of differential forms and use this to provide an elegant demonstration of how the method of images (well known in electrostatics) also works for electrodynamics in the presence of an infinite plane conducting boundary. The paper should be accessible to an…
Rapidly rotating pulsar radiation in vacuum nonlinear electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Denisov, V.I.; Pimenov, A.B.; Sokolov, V.A. [Moscow State University, Physics Department, Moscow (Russian Federation); Denisova, I.P. [Moscow Aviation Institute (National Research University), Moscow (Russian Federation)
2016-11-15
In this paper we investigate the corrections of vacuum nonlinear electrodynamics on rapidly rotating pulsar radiation and spin-down in the perturbative QED approach (post-Maxwellian approximation). An analytical expression for the pulsar's radiation intensity has been obtained and analyzed. (orig.)
International Nuclear Information System (INIS)
Newman, B.; Bowen, A.; Albright, L.
1989-01-01
This paper reports on MR imaging and videotaped US spine examinations to evaluate cord tethering were retrospectively compared in 12 children with prior myelomeningocele repair and correlated with clinical and surgical findings. Although US did not delineate normal or abnormal anatomy as well as MR imaging, both types of studies confirmed the presence of tethering in 10 patients. One child with a normal US examination and abnormal MR images had tethering confirmed surgically. A second child had a US study suggestive of tethering with equivocal MR images. Postoperative studies in eight patients correlated less well; US suggested persistent tethering in five patients and MR imaging indicated tethering in two
Biogenic nonmethane hydrocarbon emissions estimated from tethered balloon observations
Davis, K. J.; Lenschow, D. H.; Zimmerman, P. R.
1994-01-01
A new technique for estimating surface fluxes of trace gases, the mixed-layer gradient technique, is used to calculate isoprene and terpene emissions from forests. The technique is applied to tethered balloon measurements made over the Amazon forest and a pine-oak forest in Alabama at altitudes up to 300 m. The observations were made during the dry season Amazon Boundary Layer Experiment (ABLE 2A) and the Rural Oxidants in the Southern Environment 1990 experiment (ROSE I). Results from large eddy simulations of scalar transport in the clear convective boundary layer are used to infer fluxes from the balloon profiles. Profiles from the Amazon give a mean daytime emission of 3630 +/- 1400 micrograms isoprene sq m/h, where the uncertainty represents the standard deviation of the mean of eight flux estimates. Twenty profiles from Alabama give emissions of 4470 +/- 3300 micrograms isoprene sq m/h, 1740 +/- 1060 micrograms alpha-pinene sq m/h, and 790 +/- 560 micrograms beta-pinene sq m/h, respectively. These results are in agreement with emissions derived from chemical budgets. The emissions may be overestimated because of uncertainty about how to incorporate the effects of the canopy on the mixed-layer gradients. The large variability in these emission estimates is probably due to the relatively short sampling times of the balloon profiles, though spatially heterogeneous emissions may also play a role. Fluxes derived using this technique are representative of an upwind footprint of several kilometers and are independent of hydrocarbon oxidation rate and mean advection.
A Simple Flight Mill for the Study of Tethered Flight in Insects.
Attisano, Alfredo; Murphy, James T; Vickers, Andrew; Moore, Patricia J
2015-12-10
Flight in insects can be long-range migratory flights, intermediate-range dispersal flights, or short-range host-seeking flights. Previous studies have shown that flight mills are valuable tools for the experimental study of insect flight behavior, allowing researchers to examine how factors such as age, host plants, or population source can influence an insects' propensity to disperse. Flight mills allow researchers to measure components of flight such as speed and distance flown. Lack of detailed information about how to build such a device can make their construction appear to be prohibitively complex. We present a simple and relatively inexpensive flight mill for the study of tethered flight in insects. Experimental insects can be tethered with non-toxic adhesives and revolve around an axis by means of a very low friction magnetic bearing. The mill is designed for the study of flight in controlled conditions as it can be used inside an incubator or environmental chamber. The strongest points are the very simple electronic circuitry, the design that allows sixteen insects to fly simultaneously allowing the collection and analysis of a large number of samples in a short time and the potential to use the device in a very limited workspace. This design is extremely flexible, and we have adjusted the mill to accommodate different species of insects of various sizes.
Tethered Nanoparticle–Polymer Composites: Phase Stability and Curvature
Srivastava, Samanvaya
2012-04-17
Phase behavior of poly(ethylene glycol) (PEG) tethered silica nanoparticles dispersed in PEG hosts is investigated using small-angle X-ray scattering. Phase separation in dispersions of densely grafted nanoparticles is found to display strikingly different small-angle X-ray scattering signatures in comparison to phase-separated composites comprised of bare or sparsely grafted nanoparticles. A general diagram for the dispersion state and phase stability of polymer tethered nanoparticle-polymer composites incorporating results from this as well as various other contemporary studies is presented. We show that in the range of moderate to high grafting densities the dispersion state of nanoparticles in composites is largely insensitive to the grafting density of the tethered chains and chemistry of the polymer host. Instead, the ratio of the particle diameter to the size of the tethered chain and the ratio of the molecular weights of the host and tethered polymer chains (P/N) are shown to play a dominant role. Additionally, we find that well-functionalized nanoparticles form stable dispersions in their polymer host beyond the P/N limit that demarcates the wetting/dewetting transition in polymer brushes on flat substrates interacting with polymer melts. A general strategy for achieving uniform nanoparticle dispersion in polymers is proposed. © 2012 American Chemical Society.
Tethered Pyrotechnic Apparatus for Acquiring a Ground Sample
Jones, Jack; Zimmerman, Wayne; Wu, Jiunn Jenq; Badescu, Mircea; Sherrit, Stewart
2009-01-01
A proposed alternative design for the balloon-borne ground-sampling system described in the immediately preceding article would not rely on free fall to drive a harpoonlike sample-collecting device into the ground. Instead, the harpoon-like sample-collecting device would be a pyrotechnically driven, tethered projectile. The apparatus would include a tripod that would be tethered to the gondola. A gun for shooting the projectile into the ground would be mounted at the apex of the tripod. The gun would include an electronic trigger circuit, a chamber at the breech end containing a pyrotechnic charge, and a barrel. A sabot would be placed in the barrel just below the pyrotechnic charge, and the tethered projectile would be placed in the barrel just below the sabot. The tripod feet would be equipped with contact sensors connected to the trigger circuit. In operation, the tripod would be lowered to the ground on its tether. Once contact with the ground was detected by the sensors on all three tripod feet, the trigger circuit would fire the pyrotechnic charge to drive the projectile into the ground. (Requiring contact among all three tripod feet and the ground would ensure that the projectile would be fired into the ground, rather than up toward the gondola or the balloon.) The tethered projectile would then be reeled back up to the gondola for analysis of the sample.
Numerical Simulation of Tethered Underwater Kites for Power Generation
Ghasemi, Amirmahdi; Olinger, David; Tryggvason, Gretar
2015-11-01
An emerging renewable energy technology, tethered undersea kites (TUSK), which is used to extract hydrokinetic energy from ocean and tidal currents, is studied. TUSK systems consist of a rigid-winged ``kite,'' or glider, moving in an ocean current which is connected by tethers to a floating buoy on the ocean surface. The TUSK kite is a current speed enhancement device since the kite can move in high-speed, cross-current motion at 4-6 times the current velocity, thus producing more power than conventional marine turbines. A computational simulation is developed to simulate the dynamic motion of an underwater kite and extendable tether. A two-step projection method within a finite volume formulation, along with an Open MP acceleration method, is employed to solve the Navier-Stokes equations. An immersed boundary method is incorporated to model the fluid-structure interaction of the rigid kite (with NACA 0012 airfoil shape in 2D and NACA 0021 airfoil shape in 3D simulations) and the fluid flow. PID control methods are used to adjust the kite angle of attack during power (tether reel-out) and retraction (reel-in) phases. Two baseline simulations (for kite motions in two and three dimensions) are studied, and system power output, flow field vorticity, tether tension, and hydrodynamic coefficients (lift and drag) for the kite are determined. The simulated power output shows good agreement with established theoretical results for a kite moving in two-dimensions.
The secret life of tethers: the role of tethering factors in SNARE complex regulation
Directory of Open Access Journals (Sweden)
Michelle L Dubuke
2016-05-01
Full Text Available Trafficking in eukaryotic cells is a tightly regulated process to ensure correct cargo delivery to the proper destination organelle or plasma membrane. In this review, we focus on how the vesicle fusion machinery, the SNARE complex, is regulated by the interplay of the multisubunit tethering complexes (MTC with the SNAREs and Sec1/Munc18 (SM proteins. Although these factors are used in different stages of membrane trafficking, e.g. Golgi to plasma membrane transport vs vacuolar fusion, and in a variety of diverse eukaryotic cell types, many commonalities between their functions are being revealed. We explore the various protein-protein interactions and findings from functional reconstitution studies in order to highlight both their common features and the differences in their modes of regulation. These studies serve as a starting point for mechanistic explorations in other systems.
Low Earth Orbit Environmental Effects on Space Tether Materials
Finckernor, Miria M.; Gitlemeier, Keith A.; Hawk, Clark W.; Watts, Ed
2005-01-01
Atomic oxygen (AO) and ultraviolet (UV) radiation erode and embrittle most polymeric materials. This research was designed to test several different materials and coatings under consideration for their application to space tethers, for resistance to these effects. The samples were vacuum dehydrated, weighed and then exposed to various levels of AO or UV radiation at the NASA Marshall Space Flight Center. They were then re-weighed to determine mass loss due to atomic oxygen erosion, inspected for damage and tensile tested to determine strength loss. The experiments determined that the Photosil coating process, while affording some protection, damaged the tether materials worse than the AO exposure. TOR-LM also failed to fully protect the materials, especially from UV radiation. The POSS and nickel coatings did provide some protection to the tethers, which survived the entire test regime. M5 was tested, uncoated, and survived AO exposure, though its brittleness prevented any tensile testing.
Tethered balloon-based measurements of meteorological variables and aerosols
Sentell, R. J.; Storey, R. W.; Chang, J. J. C.; Jacobsen, S. J.
1976-01-01
Tethered balloon based measurements of the vertical distributions of temperature, humidity, wind speed, and aerosol concentrations were taken over a 4-hour period beginning at sunrise on June 29, 1976, at Wallops Island, Virginia. Twelve consecutive profiles of each variable were obtained from ground to about 500 meters. These measurements were in conjuction with a noise propagation study on remotely arrayed acoustic range (ROMAAR) at Wallops Flight Center. An organized listing of these vertical soundings is presented. The tethered balloon system configuration utilized for these measurements is described.
Use of top tethers with forward-facing child restraints: observations and driver interviews.
Eichelberger, Angela H; Decina, Lawrence E; Jermakian, Jessica S; McCartt, Anne T
2014-02-01
Despite the safety benefits, many parents do not use top tethers with forward-facing child restraints. Detailed information was collected about why parents are not using tethers. The sample included 479 drivers who had forward-facing child restraints installed in passenger vehicles equipped with tether anchors. The survey was conducted primarily at shopping centers, recreation facilities, child care facilities, car seat check events, and health care facilities in mostly suburban areas surrounding Philadelphia, Washington, DC, Fredericksburg (VA), and Seattle. Drivers were surveyed about their knowledge and use of tethers and experience with child restraints. Tether use was observed to verify whether tethers were being used correctly. Fifty-six percent of forward-facing child restraints were installed with the tether; 39% were installed with the tether used correctly. The tether was used with 71% of LATCH lower anchor installations and 33% of seat belt installations. Drivers who installed child restraints without tethers most often said they did not know about the tether or how to use it. Although the tether use rate was slightly higher in the current research than in previous studies, many parents and caregivers still use forward-facing child restraints without attaching the tether. Because the main problem is lack of awareness of the tether or how to use it, public education should focus specifically on the safety benefits of tethers and how to use them. Information about why caregivers fail to use top tethers is potentially useful to child restraint manufacturers, child passenger safety technicians, and others who work with parents to improve motor vehicle safety. Copyright © 2013 Elsevier Ltd and National Safety Council. All rights reserved.
Becchi-Rouet-Stora-Tyutin quantization of histories electrodynamics
International Nuclear Information System (INIS)
Noltingk, Duncan
2002-01-01
This article is a continuation of earlier work where a classical history theory of pure electrodynamics was developed in which the history fields have five components. The extra component is associated with an extra constraint, thus enlarging the gauge group of histories electrodynamics. In this article we quantize the classical theory developed previously by two methods. First we quantize the reduced classical history space to obtain a reduced quantum history theory. Second we quantize the classical BRST-extended history space, and use the Becchi-Rouet-Stora-Tyutin charge to define a 'cohomological' quantum history theory. Finally, we show that the reduced history theory is isomorphic (as a history theory) to the cohomological history theory
Advances in FDTD computational electrodynamics photonics and nanotechnology
Oskooi, Ardavan; Johnson, Steven G
2013-01-01
Advances in photonics and nanotechnology have the potential to revolutionize humanity s ability to communicate and compute. To pursue these advances, it is mandatory to understand and properly model interactions of light with materials such as silicon and gold at the nanoscale, i.e., the span of a few tens of atoms laid side by side. These interactions are governed by the fundamental Maxwell s equations of classical electrodynamics, supplemented by quantum electrodynamics. This book presents the current state-of-the-art in formulating and implementing computational models of these interactions. Maxwell s equations are solved using the finite-difference time-domain (FDTD) technique, pioneered by the senior editor, whose prior Artech books in this area are among the top ten most-cited in the history of engineering. You discover the most important advances in all areas of FDTD and PSTD computational modeling of electromagnetic wave interactions. This cutting-edge resource helps you understand the latest develo...
Electrodynamic wireless power transmission to a torsional receiver
International Nuclear Information System (INIS)
McEachern, K M; Arnold, D P
2013-01-01
This paper presents a wireless power transmission (WPT) concept that uses electrodynamic coupling and torsional motion of a permanent magnet in the receiver. The system is shown to transfer an average power of 3.09 mW (power density equal to 143 μW/cm 3 ) over a distance of 1 cm, an average power of 1.98 mW over a distance of 2 cm, and an average power of 126 μW over a distance of 7 cm. We also demonstrate unaltered power transmission through conductive media, including a human hand and an aluminum plate, highlighting a key advantage of the electrodynamic wireless power transmission approach
Methods for accurate calculations in high-energy quantum electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Ericsson, K. E. [Institute of Theoretical Physics, Uppsala (Sweden)
1963-01-15
In this paper ''quantum electrodynamics'' (QED) will be used in the sense of a closed theory of point-like photons and electrons. Muons could then easily be included. We make the usual assumption that the perturbation expansion of renormalized QED gives at least an asymptotic expression of the exact theory, i.e. that the sum over a few terms in the beginning of the perturbation series is a good approximation of the exact theory. We expect QED in this sense to break down at small distances, i. e. at large momentum transfers, because of structure effects resulting from other kinds of interaction, primarily the interactions of the electromagnetic field with the current of strongly interacting particles. This will first show up as vacuum polarization through mesons. On the other hand we have no reason to believe that the fundamental theory of electrodynamics, i.e. the theory of a massless vector field interacting with a.conserved current, will break down.
On foundational and geometric critical aspects of quantum electrodynamics
International Nuclear Information System (INIS)
Prugovecki, E.
1994-01-01
The foundational difficulties encountered by the conventional formulation of quantum electrodynamics, and the criticism by Dirac Schwinger, Rohrlich, and others, aimed at some of the physical and mathematical premises underlying that formulation, are reviewed and discussed. The basic failings of the conventional methods of quantization of the electromagnetic field are pointed out, especially with regard to the issue of local (anti) commutativity of quantum fields as an embodiment of relativistic microcausality. A brief description is given of a recently advanced new type of approach to quantum electrodynamics, and to quantum field theory in general, which is epistemically based on intrinsically quantum ideas about the physical nature of spacetime, and is mathematically based on a fiber theoretical formulation of quantum geometries, aimed in part at removing the aforementioned difficulties and inconsistencies. It is shown that these ideas can be traced to a conceptualization of spacetime outlined by Einstein in the last edition of his well-known semipopular exposition of relativity theory. 57 refs
Fractal electrodynamics via non-integer dimensional space approach
Tarasov, Vasily E.
2015-09-01
Using the recently suggested vector calculus for non-integer dimensional space, we consider electrodynamics problems in isotropic case. This calculus allows us to describe fractal media in the framework of continuum models with non-integer dimensional space. We consider electric and magnetic fields of fractal media with charges and currents in the framework of continuum models with non-integer dimensional spaces. An application of the fractal Gauss's law, the fractal Ampere's circuital law, the fractal Poisson equation for electric potential, and equation for fractal stream of charges are suggested. Lorentz invariance and speed of light in fractal electrodynamics are discussed. An expression for effective refractive index of non-integer dimensional space is suggested.
Solid-state cavity quantum electrodynamics using quantum dots
International Nuclear Information System (INIS)
Gerard, J.M.; Gayral, B.; Moreau, E.; Robert, I.; Abram, I.
2001-01-01
We review the recent development of solid-state cavity quantum electrodynamics using single self-assembled InAs quantum dots and three-dimensional semiconductor microcavities. We discuss first prospects for observing a strong coupling regime for single quantum dots. We then demonstrate that the strong Purcell effect observed for single quantum dots in the weak coupling regime allows us to prepare emitted photons in a given state (the same spatial mode, the same polarization). We present finally the first single-mode solid-state source of single photons, based on an isolated quantum dot in a pillar microcavity. This optoelectronic device, the first ever to rely on a cavity quantum electrodynamics effect, exploits both Coulomb interaction between trapped carriers in a single quantum dot and single mode photon tunneling in the microcavity. (author)
Successive canonical transformation in model two-body electrodynamics
International Nuclear Information System (INIS)
Raha, S.
1978-10-01
The possibility is investigated of bypassing the no interaction theorum of Currie, Jordan and Sudarshan for direct action Lagrangians. Starting with the field theoretic description of a two-body electrodynamic problem, the field variable is solved for in terms of the particle variables, which paves the way to write an action-at-a-distance Hamiltonian for the problem. A suitable transformation is found which uncouples the field and the particle variables in the interaction up to order e 2 . It is shown that this transformation leaves the statement of Newton's 2nd law unchanged which also agrees with the standard results of electrodynamics. This allows for the identification of canonical variables for the proper action-at-a-distance problem. 19 references
Massive lepton pair production in massive quantum electrodynamics
International Nuclear Information System (INIS)
Raychaudhuri, P.
1976-01-01
The pp → l + +l - +x inclusive interaction has been studied at high energies in terms of the massive quantum electrodynamics. The differential cross-section (dsigma/dQ 2 ) is derived and proves to be proportional to Q -4 , where Q-mass of the lepton pair. Basic features of the cross-section are demonstrated to be consistent with the Drell-Yan model
Matsubara-Fradkin thermodynamical quantization of Podolsky electrodynamics
International Nuclear Information System (INIS)
Bonin, C. A.; Pimentel, B. M.
2011-01-01
In this work, we apply the Matsubara-Fradkin formalism and the Nakanishi's auxiliary field method to the quantization of the Podolsky electrodynamics in thermodynamic equilibrium. This approach allows us to write consistently the path integral representation for the partition function of gauge theories in a simple manner. Furthermore, we find the Dyson-Schwinger-Fradkin equations and the Ward-Fradkin-Takahashi identities for the Podolsky theory. We also write the most general form for the polarization tensor in thermodynamic equilibrium.
Logarithmic of mass singularities theorem in non massive quantum electrodynamics
International Nuclear Information System (INIS)
Mares G, R.; Luna, H.
1997-01-01
We give an explicit example of the use of dimensional regularization to calculate in a unified approach, all the ultraviolet, infrared and mass singularities, by considering the LMS (logarithms of mass singularities) theorem in the frame of massless QED (Quantum electrodynamics). In the calculation of the divergent part of the cross section, all singularities are found to cancel provided soft and hard photon emission are both taken into account. (Author)
Few Issues Related to an Electrodynamic Exciter Control
Čala, M.
2015-01-01
There are multiple problems to solve when controlling an electromagnetic exciter for vibrations generation. Main challenge is to straighten a frequency response of an exciter which is normally not uniform due to resonances resulting from the mechanical construction of an exciter, specimen to test, or mounting fixture. This paper describes number of aspects to consider, which arose during implementation of the control system for small electrodynamic exciter on the Department of Control and Ins...
Quantum electrodynamics and light rays. [Two-point correlation functions
Energy Technology Data Exchange (ETDEWEB)
Sudarshan, E.C.G.
1978-11-01
Light is a quantum electrodynamic entity and hence bundles of rays must be describable in this framework. The duality in the description of elementary optical phenomena is demonstrated in terms of two-point correlation functions and in terms of collections of light rays. The generalizations necessary to deal with two-slit interference and diffraction by a rectangular slit are worked out and the usefulness of the notion of rays of darkness illustrated. 10 references.
Clothed Particles in Quantum Electrodynamics and Quantum Chromodynamics
Directory of Open Access Journals (Sweden)
Shebeko Alexander
2016-01-01
Full Text Available The notion of clothing in quantum field theory (QFT, put forward by Greenberg and Schweber and developed by M. Shirokov, is applied in quantum electrodynamics (QED and quantum chromodynamics (QCD. Along the guideline we have derived a novel analytic expression for the QED Hamiltonian in the clothed particle representation (CPR. In addition, we are trying to realize this notion in QCD (to be definite for the gauge group SU(3 when drawing parallels between QCD and QED.
Quantized fluctuational electrodynamics for three-dimensional plasmonic structures
DEFF Research Database (Denmark)
Partanen, Mikko; Häyrynen, Teppo; Tulkki, Jukka
2017-01-01
We recently introduced a quantized fluctuational electrodynamics (QFED) formalism that provides a physically insightful definition of an effective position-dependent photon-number operator and the associated ladder operators. However, this far the formalism has been applicable only for the normal...... formalism, we apply it to study the local steady-state photon numbers and field temperatures in a light-emitting near-surface InGaN quantum-well structure with a metallic coating supporting surface plasmons....
Fixed point structure of quenched, planar quantum electrodynamics
International Nuclear Information System (INIS)
Love, S.T.
1986-07-01
Gauge theories exhibiting a hierarchy of fermion mass scales may contain a pseudo-Nambu-Boldstone boson of spontaneously broken scale invariance. The relation between scale and chiral symmetry breaking is studied analytically in quenched, planar quantum electrodynamics in four dimensions. The model possesses a novel nonperturbative ultraviolet fixed point governing its strong coupling phase which requires the mixing of four fermion operators. 12 refs
Progress in quantum electrodynamics theory of highly charged ions
Volotka, A. V.; Glazov, D. A.; Plunien, G.; Shabaev, V. M.
2013-01-01
Recent progress in quantum electrodynamics (QED) calculations of highly charged ions is reviewed. The theoretical predictions for the binding energies, the hyperfine splittings, and the g factors are presented and compared with available experimental data. Special attention is paid to tests of bound-state QED at strong field regime. Future prospects for tests of QED at the strongest electric and magnetic fields as well as for determination of the fine structure constant and the nuclear magnet...
GENERALIZED p-FORMS ELECTRODYNAMICS IN CLIFFORD SPACES
Castro, C
2003-01-01
Using Clifford algebraic methods we describe how to generalize Maxwell theory of Electrodynamics asociated with ordinary point-charges to a generalized Maxwell theory in Clifford spaces involving extended-charges and p-forms of arbitrary rank. Clifford algebras contain the appropriate algebraic-geometric features to implement the principle of polydimensional transformations (branes of different dimensionality are rotated into each other) that could possibly lead to a proper formulation of string and M theory.
Non-US electrodynamic launchers research and development
Energy Technology Data Exchange (ETDEWEB)
Parker, J.V.; Batteh, J.H.; Greig, J.R.; Keefer, D.; McNab, I.R.; Zabar, Z.
1994-11-01
Electrodynamic launcher research and development work of scientists outside the United States is analyzed and assessed by six internationally recognized US experts in the field of electromagnetic and electrothermal launchers. The assessment covers five broad technology areas: (1) Experimental railguns; (2) Railgun theory and design; (3) Induction launchers; (4) Electrothermal guns; (5) Energy storage and power supplies. The overall conclusion is that non-US work on electrodynamic launchers is maturing rapidly after a relatively late start in many countries. No foreign program challenges the US efforts in scope, but it is evident that the United States may be surpassed in some technologies within the next few years. Until recently, published Russian work focused on hypervelocity for research purposes. Within the last two years, large facilities have been described where military-oriented development has been underway since the mid-1980s. Financial support for these large facilities appears to have collapsed, leaving no effective effort to develop practical launchers for military or civilian applications. Electrodynamic launcher research in Europe is making rapid progress by focusing on a single application, tactical launchers for the military. Four major laboratories, in Britain, France, Germany, and the Netherlands, are working on this problem. Though narrower in scope than the US effort, the European work enjoys a continuity of support that has accelerated its progress. The next decade will see the deployment of electrodynamic launcher technology, probably in the form of an electrothermal-chemical upgrade for an existing gun system. The time scale for deployment of electromagnetic launchers is entirely dependent on the level of research-and-development effort. If resources remain limited, the advantage will lie with cooperative efforts that have reasonably stable funding such as the present French-German program.
Dimensional regularization and infrared divergences in quantum electrodynamics
International Nuclear Information System (INIS)
Marculescu, S.
1979-01-01
Dimensional continuation was devised as a powerful regularization method for ultraviolet divergences in quantum field theories. Recently it was clear, at least for quantum electrodynamics, that such a method could be employed for factorizing out infrared divergences from the on-shell S-matrix elements. This provides a renormalization scheme on the electron mass-shell without using a gauge violating ''photon mass''. (author)
Abrikosov vortices from electrodynamics with c-number Dirac spinors
International Nuclear Information System (INIS)
Cabo, A.; Perez-Martinez, A.M.
1986-01-01
We obtain the solutions of the classical equations of motion in electrodynamics with c-number fermion fields in the presence of a uniform charge background. Translationally invariant and cylindrically symmetric exact solutions are found. We also find an approximate cylindrically symmetric solution similar to the Abrikosov vortex in a type-II superconductor. The corresponding value of the magnetic flux is hc/2e
Scale solutions and coupling constant in electrodynamics of vector particles
International Nuclear Information System (INIS)
Arbuzov, B.A.; Boos, E.E.; Kurennoy, S.S.
1980-01-01
A new approach in nonrenormalizable gauge theories is studied, the electrodynamics of vector particles being taken as an example. One and two-loop approximations in Schwinger-Dyson set of equations are considered with account for conditions imposed by gauge invariance. It is shown, that solutions with scale asymptotics can occur in this case but only for a particular value of coupling constant. This value in solutions obtained is close to the value of the fine structure constant α=1/137
Split Octonion electrodynamics and unified fields of dyons
International Nuclear Information System (INIS)
Bisht, P.S.
2004-01-01
Split octonion electrodynamics has been developed in terms of Zorn's vector matrix realization by reformulating electromagnetic potential, current, field tensor and other dynamical quantities. Corresponding field equation (Unified Maxwell's equations) and equation of motion have been reformulated by means of split octonion and its Zorn vector realization in unique, simpler and consistent manner. It has been shown that this theory reproduces the dyon field equations in the absence of gravito-dyons and vice versa
On the renormalization group equations of quantum electrodynamics
International Nuclear Information System (INIS)
Hirayama, Minoru
1980-01-01
The renormalization group equations of quantum electrodynamics are discussed. The solution of the Gell-Mann-Low equation is presented in a convenient form. The interrelation between the Nishijima-Tomozawa equation and the Gell-Mann-Low equation is clarified. The reciprocal effective charge, so to speak, turns out to play an important role to discuss renormalization group equations. Arguments are given that the reciprocal effective charge vanishes as the renormalization momentum tends to infinity. (author)
Problems of quantum electrodynamics with external field creating pairs
International Nuclear Information System (INIS)
Fradkin, E.S.; Gitman, D.M.
1979-11-01
This paper is a preliminary version of a review of the results obtained by the authors and their collaborators which mainly concern problems of quantum electrodynamics with the pair-creating external field. In this paper the Furry picture is constructed for quantum electrodynamics with the pair-creating external field. It is shown, that various Green functions in the external field arise in the theory in a natural way. Special features of usage of the unitarity conditions for calculating the total probabilities of transitions are discussed. Perturbation theory for determining the mean electromagnetic field is constructed. Effective Lagrangians for pair-creating fields are built. One of the possible ways to introduce external field in quantum electrodynamics is considered. All the Green functions arising in the theory suggested are calculated for a constant field and a plane wave field. For the case of the electric field the total probability of creation of pairs from the vacuum accompanied by the photon irradiation and the total probability of transition from a single-electron state accompanied by the photon irradiation and creation of pairs are obtained by using the formulated rules for calculating the total probabilities of transitions. (author)
Relative Contribution of Arms and Legs in 30 s Fully Tethered Front Crawl Swimming
Directory of Open Access Journals (Sweden)
Pedro G. Morouço
2015-01-01
Full Text Available The relative contribution of arm stroke and leg kicking to maximal fully tethered front crawl swimming performance remains to be solved. Twenty-three national level young swimmers (12 male and 11 female randomly performed 3 bouts of 30 s fully tethered swimming (using the whole body, only the arm stroke, and only the leg kicking. A load-cell system permitted the continuous measurement of the exerted forces, and swimming velocity was calculated from the time taken to complete a 50 m front crawl swim. As expected, with no restrictions swimmers were able to exert higher forces than that using only their arm stroke or leg kicking. Estimated relative contributions of arm stroke and leg kicking were 70.3% versus 29.7% for males and 66.6% versus 33.4% for females, with 15.6% and 13.1% force deficits, respectively. To obtain higher velocities, male swimmers are highly dependent on the maximum forces they can exert with the arm stroke (r=0.77, P<0.01, whereas female swimmers swimming velocity is more related to whole-body mean forces (r=0.81, P<0.01. The obtained results point that leg kicking plays an important role over short duration high intensity bouts and that the used methodology may be useful to identify strength and/or coordination flaws.
Constraining Born-Infeld-like nonlinear electrodynamics using hydrogen's ionization energy
Energy Technology Data Exchange (ETDEWEB)
Akmansoy, P.N. [Universidade Federal do Rio Grande do Norte, Departamento de Fisica Teorica e Experimental, Natal (Brazil); Medeiros, L.G. [Universidade Estadual Paulista, Instituto de Fisica Teorica, Sao Paulo, SP (Brazil); Universidade Federal do Rio Grande do Norte, Escola de Ciencia e Tecnologia, Natal, RN (Brazil)
2018-02-15
In this work, the hydrogen's ionization energy was used to constrain the free parameter b of three Born-Infeld-like electrodynamics namely Born-Infeld itself, Logarithmic electrodynamics and Exponential electrodynamics. An analytical methodology capable of calculating the hydrogen ground state energy level correction for a generic nonlinear electrodynamics was developed. Using the experimental uncertainty in the ground state energy of the hydrogen atom, the bound b > 5.37 x 10{sup 20}K(V)/(m), where K = 2, 4√(2)/3 and √(π) for the Born-Infeld, Logarithmic and Exponential electrodynamics respectively, was established. In the particular case of Born-Infeld electrodynamics, the constraint found for b was compared with other constraints present in the literature. (orig.)
Hierarchical Structure in Semicrystalline Polymers Tethered to Nanospheres
Kim, Sung A
2014-01-28
We report on structural and dynamic transitions of polymers tethered to nanoparticles. In particular, we use X-ray diffraction, vibrational spectroscopy, and thermal measurements to investigate multiscale structure and dynamic transitions of poly(ethylene glycol) (PEG) chains densely grafted to SiO2 nanoparticles. The approach used for synthesizing these hybrid particles leads to homogeneous SiO2-PEG composites with polymer grafting densities as high as 1.5 chains/nm2, which allows the hybrid materials to exist as self-suspended suspensions with distinct hierarchical structure and thermal properties. On angstrom and nanometer length scales, the tethered PEG chains exhibit more dominant TTG conformations and helix unit cell structure, in comparison to the untethered polymer. The nanoparticle tethered PEG chains are also reported to form extended crystallites on tens of nanometers length scales and to exhibit more stable crystalline structure on small dimensions. On length scales comparable to the size of each hybrid SiO 2-PEG unit, the materials are amorphous presumably as a result of the difficulty fitting the nanoparticle anchors into the PEG crystal lattice. This structural change produces large effects on the thermal transitions of PEG molecules tethered to nanoparticles. © 2014 American Chemical Society.
75 FR 47316 - Centennial Challenges 2010 Strong Tether Challenge
2010-08-05
... NATIONAL AERONAUTICS AND SPACE ADMINISTRATION Centennial Challenges 2010 Strong Tether Challenge... teams that wish to compete may register. Centennial Challenges is a program of prize competitions to..., please visit: http://www.spaceward.org/elevator2010-ts . For general information on the NASA Centennial...
Relaxation Dynamics of Nanoparticle-Tethered Polymer Chains
Kim, Sung A
2015-09-08
© 2015 American Chemical Society. Relaxation dynamics of nanoparticle-tethered cis-1,4-polyisoprene (PI) are investigated using dielectric spectroscopy and rheometry. A model system composed of polymer chains densely grafted to spherical SiO2 nanoparticles to form self-suspended suspensions facilitates detailed studies of slow global chain and fast segmental mode dynamics under surface and geometrical confinement-from experiments performed in bulk materials. We report that unentangled polymer molecules tethered to nanoparticles relax far more slowly than their tethered entangled counterparts. Specifically, at fixed grafting density we find, counterintuitively, that increasing the tethered polymer molecular weight up to values close to the entanglement molecular weight speeds up chain relaxation dynamics. Decreasing the polymer grafting density for a fixed molecular weight has the opposite effect: it dramatically slows down chain relaxation, increases interchain coupling, and leads to a transition in rheological response from simple fluid behavior to viscoelastic fluid behavior for tethered PI chains that are unentangled by conventional measures. Increasing the measurement temperature produces an even stronger elastic response and speeds up molecular relaxation at a rate that decreases with grafting density and molecular weight. These observations are discussed in terms of chain confinement driven by crowding between particles and by the existence of an entropic attractive force produced by the space-filling constraint on individual chains in a self-suspended material. Our results indicate that the entropic force between densely grafted polymer molecules couples motions of individual chains in an analogous manner to reversible cross-links in associating polymers.
Modelling a tethered mammalian sperm cell undergoing hyperactivation
Curtis, M.P.
2012-09-01
The beat patterns of mammalian sperm flagella can be categorised into two different types. The first involves symmetric waves propagating down the flagellum with a net linear propulsion of the sperm cell. The second, hyperactive, waveform is classified by vigorous asymmetric waves of higher amplitude, lower wavenumber and frequency propagating down the flagellum resulting in highly curved trajectories. The latter beat pattern is part of the capacitation process whereby sperm prepare for the prospective penetration of the zona pellucida and fusion with the egg. Hyperactivation is often observed to initiate as sperm escape from epithelial and ciliary bindings formed within the isthmic regions of the female oviducts, leading to a conjecture in the literature that this waveform is mechanically important for sperm escape. Hence, we explore the mechanical effects of hyperactivation on a tethered sperm, focussing on a Newtonian fluid. Using a resistive force theory model we demonstrate that hyperactivation can indeed generate forces that pull the sperm away from a tethering point and consequently a hyperactivated sperm cell bound to an epithelial surface need not always be pushed by its flagellum. More generally, directions of the forces generated by tethered flagella are insensitive to reductions in beat frequency and the detailed flagellar responses depend on the nature of the binding at the tethering point. Furthermore, waveform asymmetry and amplitude increases enhance the tendency for a tethered flagellum to start tugging on its binding. The same is generally predicted to be true for reductions in the wavenumber of the flagellum beat, but not universally so, emphasising the dynamical complexity of flagellar force generation. Finally, qualitative observations drawn from experimental data of human sperm bound to excised female reproductive tract are also presented and are found to be consistent with the theoretical predictions. © 2012 Elsevier Ltd.
Modelling a tethered mammalian sperm cell undergoing hyperactivation
Curtis, M.P.; Kirkman-Brown, J.C.; Connolly, T.J.; Gaffney, E.A.
2012-01-01
The beat patterns of mammalian sperm flagella can be categorised into two different types. The first involves symmetric waves propagating down the flagellum with a net linear propulsion of the sperm cell. The second, hyperactive, waveform is classified by vigorous asymmetric waves of higher amplitude, lower wavenumber and frequency propagating down the flagellum resulting in highly curved trajectories. The latter beat pattern is part of the capacitation process whereby sperm prepare for the prospective penetration of the zona pellucida and fusion with the egg. Hyperactivation is often observed to initiate as sperm escape from epithelial and ciliary bindings formed within the isthmic regions of the female oviducts, leading to a conjecture in the literature that this waveform is mechanically important for sperm escape. Hence, we explore the mechanical effects of hyperactivation on a tethered sperm, focussing on a Newtonian fluid. Using a resistive force theory model we demonstrate that hyperactivation can indeed generate forces that pull the sperm away from a tethering point and consequently a hyperactivated sperm cell bound to an epithelial surface need not always be pushed by its flagellum. More generally, directions of the forces generated by tethered flagella are insensitive to reductions in beat frequency and the detailed flagellar responses depend on the nature of the binding at the tethering point. Furthermore, waveform asymmetry and amplitude increases enhance the tendency for a tethered flagellum to start tugging on its binding. The same is generally predicted to be true for reductions in the wavenumber of the flagellum beat, but not universally so, emphasising the dynamical complexity of flagellar force generation. Finally, qualitative observations drawn from experimental data of human sperm bound to excised female reproductive tract are also presented and are found to be consistent with the theoretical predictions. © 2012 Elsevier Ltd.
Autonomous Vision-Based Tethered-Assisted Rover Docking
Tsai, Dorian; Nesnas, Issa A.D.; Zarzhitsky, Dimitri
2013-01-01
Many intriguing science discoveries on planetary surfaces, such as the seasonal flows on crater walls and skylight entrances to lava tubes, are at sites that are currently inaccessible to state-of-the-art rovers. The in situ exploration of such sites is likely to require a tethered platform both for mechanical support and for providing power and communication. Mother/daughter architectures have been investigated where a mother deploys a tethered daughter into extreme terrains. Deploying and retracting a tethered daughter requires undocking and re-docking of the daughter to the mother, with the latter being the challenging part. In this paper, we describe a vision-based tether-assisted algorithm for the autonomous re-docking of a daughter to its mother following an extreme terrain excursion. The algorithm uses fiducials mounted on the mother to improve the reliability and accuracy of estimating the pose of the mother relative to the daughter. The tether that is anchored by the mother helps the docking process and increases the system's tolerance to pose uncertainties by mechanically aligning the mating parts in the final docking phase. A preliminary version of the algorithm was developed and field-tested on the Axel rover in the JPL Mars Yard. The algorithm achieved an 80% success rate in 40 experiments in both firm and loose soils and starting from up to 6 m away at up to 40 deg radial angle and 20 deg relative heading. The algorithm does not rely on an initial estimate of the relative pose. The preliminary results are promising and help retire the risk associated with the autonomous docking process enabling consideration in future martian and lunar missions.
Learning characteristics of a space-time neural network as a tether skiprope observer
Lea, Robert N.; Villarreal, James A.; Jani, Yashvant; Copeland, Charles
1993-01-01
The Software Technology Laboratory at the Johnson Space Center is testing a Space Time Neural Network (STNN) for observing tether oscillations present during retrieval of a tethered satellite. Proper identification of tether oscillations, known as 'skiprope' motion, is vital to safe retrieval of the tethered satellite. Our studies indicate that STNN has certain learning characteristics that must be understood properly to utilize this type of neural network for the tethered satellite problem. We present our findings on the learning characteristics including a learning rate versus momentum performance table.
One kilometer (1 km) electric solar wind sail tether produced automatically.
Seppänen, Henri; Rauhala, Timo; Kiprich, Sergiy; Ukkonen, Jukka; Simonsson, Martin; Kurppa, Risto; Janhunen, Pekka; Hæggström, Edward
2013-09-01
We produced a 1 km continuous piece of multifilament electric solar wind sail tether of μm-diameter aluminum wires using a custom made automatic tether factory. The tether comprising 90,704 bonds between 25 and 50 μm diameter wires is reeled onto a metal reel. The total mass of 1 km tether is 10 g. We reached a production rate of 70 m/24 h and a quality level of 1‰ loose bonds and 2‰ rebonded ones. We thus demonstrated that production of long electric solar wind sail tethers is possible and practical.
Atmospheric solar tides and their electrodynamic effects
International Nuclear Information System (INIS)
Forbes, J.M.; Lindzen, R.S.
1977-01-01
In this final part of a three-part study, the polarization electric field generated by E-region dynamo action is considered, and its consistency with presently available experimental measurements is established. This serves as an independent check on some of the results and conclusions described in Parts I and II (Forbes and Lindzen, J. Atmos. Terr. Phys.; 38:897,911 (1976)). Incoherent scatter measurements of ionospheric drifts are reviewed from the point of view of determining the origin of the polarization electric field in the quiet-time ionosphere, and are compared with the theoretical dynamo electric fields which drive the current systems in Parts I and II. The analysis indicates that the polarization fields originating from E-region dynamo action are consistent with daytime F-region drift measurements, but are in poor agreement at night. This supports previous suggestions that electric fields generated by the plasmaspheric and F-region dynamos are short-circuited by the high E-region conductivity during the day, but contribite strongly to the night-time electric field. (author)
Hu, Zhongwei; Chulhai, Dhabih V; Jensen, Lasse
2016-12-13
Surface-enhanced hyper-Raman scattering (SEHRS) is the two-photon analogue of surface-enhanced Raman scattering (SERS), which has proven to be a powerful tool to study molecular structures and surface enhancements. However, few theoretical approaches to SEHRS exist and most neglect the atomistic descriptions of the metal surface and molecular resonance effects. In this work, we present two atomistic electrodynamics-quantum mechanical models to simulate SEHRS. The first is the discrete interaction model/quantum mechanical (DIM/QM) model, which combines an atomistic electrodynamics model of the nanoparticle with a time-dependent density functional theory description of the molecule. The second model is a dressed-tensors method that describes the molecule as a point-dipole and point-quadrupole object interacting with the enhanced local field and field-gradients (FG) from the nanoparticle. In both of these models, the resonance effects are treated efficiently by means of damped quadratic response theory. Using these methods, we simulate SEHRS spectra for benzene and pyridine. Our results show that the FG effects in SEHRS play an important role in determining both the surface selection rules and the enhancements. We find that FG effects are more important in SEHRS than in SERS. We also show that the spectral features of small molecules can be accurately described by accounting for the interactions between the molecule and the local field and FG of the nanoparticle. However, at short distances between the metal and molecule, we find significant differences in the SEHRS enhancements predicted using the DIM/QM and the dressed-tensors methods.
Tethered Ozonesonde Measurements During FRAPPE July-August 2014
Oltmans, S. J.; Johnson, B.; Sterling, C. W.; Cullis, P.; Hall, E. G.; Jordan, A. F.; Wendell, J.; Schnell, R. C.; McClure-Begley, A.; Thompson, A. M.
2015-12-01
O3 and temperature profiles were measured from tethered ozonesondes from surface to 400 m above ground level on 9 days during the summer of 2014 Colorado Front Range Air Pollution and Photochemistry Experiment (FRAPPE). The portable tethered ozonesonde system was set up at one of 3 sites located next to a Colorado Department of Public Health and Environment surface monitoring station. The day and site chosen were based on the previous day O3 and weather forecast. Measurements typically began at 8:30 AM and ended at 4:30 PM, averaging 40 profiles in one day. The ozonesonde when sampling at the surface consistently read within 0-3 ppbv of the surface monitor at each of the sites with a typical daytime range of 20-90 ppbv. The hourly values were averaged at 50 meter intervals showing O3 production rates were consistently around 8 ppbv per hour from 50 to 300 meters above ground level. On sunny, light wind days the O3 mixing ratio reached a maximum of 80-90 ppbv between 14:00 and 15:00 local time. The generally constant mixing ratio with height and highest mixing ratios above the surface indicate that photochemical O3 production was taking place throughout the profile. Continuous O3 profiles from a tall tower (5 and 300 m) and daily ozonesondes tracked O3 variability through the experiment. High O3 at each site was associated with different local wind directions. At Ft. Collins winds were generally out of the southeast, at Chatfield from the northeast, and at City Park Golf Course more variable. The tether system was developed at NOAA/ESRL to provide a cost effective method to measure O3 profiles on a continuous basis. The tether system consisted of a deep sea fishing pole, electric motor driving the reel with light-weight fishing line attached to the balloon ozonesonde, a tether control box, and laptop. The in house software package monitored data and controlled the tether speed and turn-around point based on real time GPS altitude from the transmitting radiosonde.
Guo, Zhong; Johnston, Wayne; Kovtun, Oleksiy; Mureev, Sergey; Bröcker, Cornelia; Ungermann, Christian; Alexandrov, Kirill
2013-01-01
Biochemical and structural analysis of macromolecular protein assemblies remains challenging due to technical difficulties in recombinant expression, engineering and reconstitution of multisubunit complexes. Here we use a recently developed cell-free protein expression system based on the protozoan Leishmania tarentolae to produce in vitro all six subunits of the 600 kDa HOPS and CORVET membrane tethering complexes. We demonstrate that both subcomplexes and the entire HOPS complex can be reconstituted in vitro resulting in a comprehensive subunit interaction map. To our knowledge this is the largest eukaryotic protein complex in vitro reconstituted to date. Using the truncation and interaction analysis, we demonstrate that the complex is assembled through short hydrophobic sequences located in the C-terminus of the individual Vps subunits. Based on this data we propose a model of the HOPS and CORVET complex assembly that reconciles the available biochemical and structural data. PMID:24312556
On the bosonization of the massless spinor electrodynamics
International Nuclear Information System (INIS)
Mikhov, S.G.; Stoyanov, D.Ts.
1979-01-01
A method for constructing a field transformed according to a linear representation of a Lie group out of fields transformed nonlinearly under the action of the same group is proposed. This procedure is used in order to construct spinor fields out of tensor ones. Such a ''bosonization'' of the spinor field is used to reformulate the massless spinor electrodynamics in terms of nonlinear tensor fields. It appears in this formulation that the Dirac equation is reduced to a definition of the electromagnetic vector potential in terms of the nonlinear tensor fields and to the current conservations playing the role of a consistency condition for this formulation
A space-time lattice version of scalar electrodynamics
International Nuclear Information System (INIS)
Kijowski, J.; Thielmann, A.
1993-10-01
A Minkowski-lattice version of quantum scalar electrodynamics is constructed. Quantum field is consequently described in a gauge-independent way, i.e. the algebra of quantum observables of the theory is generated by gauge-invariant operators assigned to zero-, one-, and two-dimensional elements of the lattice. The operators satisfy canonical commutation relations. Field dynamics is formulated in terms of difference equations imposed on the field operators. The dynamics is obtained from a discrete version of the path-integral. (author). 19 refs
On conformal invariance in gauge theories. Quantum electrodynamics
International Nuclear Information System (INIS)
Zaikov, R.P.
1983-01-01
In the present paper another nontrivial model of the conformal quantum electrodynamics is proposed. The main hypothesis is that the electromagnetic potential together with an additional zero scale, dimensional scalar field is transformed by a nonbasic and, consequently, nondecomposable representation of the conformal group. There are found nontrivial conformal covariant two-point functions and an invariant action from which equations of motion are derived. There is considered the covariant procedure of quantization and it is shown that the norm of one-particle physical states is positive definite
On a gauge invariant subtraction scheme for massive quantum electrodynamics
International Nuclear Information System (INIS)
Abdalla, E.; Gomes, M.; Koeberle, R.
A momentum-space subtraction scheme for massive quantum electrodynamics is proposed which respects gauge invariance, in contrast to ordinary normal product techniques. As a consequence the dependence of Green functions on the ghost mass becomes very simple and formally gauge invariant normal products of degree up to four, when subtracted according to the proposed scheme, are automatically gauge invariant. As an aplication we discuss the proof of the Adler-Bardeen theorem. Zero mass limits can be taken for Green function after the integration over intermediate states has been carried out [pt
Electrodynamic Wireless Power Transmission to Rotating Magnet Receivers
International Nuclear Information System (INIS)
Garraud, A; Jimenez, J D; Garraud, N; Arnold, D P
2014-01-01
This paper presents an approach for electrodynamic wireless power transmission (EWPT) using a synchronously rotating magnet located in a 3.2 cm 3 receiver. We demonstrate wireless power transmission up to 99 mW (power density equal to 31 mW/cm 3 ) over a 5-cm distance and 5 mW over a 20-cm distance. The maximum operational frequency, and hence maximal output power, is constrained by the magnetic field amplitude. A quadratic relationship is found between the maximal output power and the magnetic field. We also demonstrate simultaneous, power transmission to multiple receivers positioned at different locations
Dimensional regularization and renormalization of Coulomb gauge quantum electrodynamics
International Nuclear Information System (INIS)
Heckathorn, D.
1979-01-01
Quantum electrodynamics is renormalized in the Coulomb gauge with covariant counter terms and without momentum-dependent wave-function renormalization constants. It is shown how to dimensionally regularize non-covariant integrals occurring in this guage, and prove that the 'minimal' subtraction prescription excludes non-covariant counter terms. Motivated by the need for a renormalized Coulomb gauge formalism in certain practical calculations, the author introduces a convenient prescription with physical parameters. The renormalization group equations for the Coulomb gauge are derived. (Auth.)
Proposed experimental test of an alternative electrodynamic theory of superconductors
Energy Technology Data Exchange (ETDEWEB)
Hirsch, J.E., E-mail: jhirsch@ucsd.edu
2015-01-15
Highlights: • A new experimental test of electric screening in superconductors is proposed. • The electric screening length is predicted to be much larger than in normal metals. • The reason this was not seen in earlier experiments is explained. • This is not predicted by the conventional BCS theory of superconductivity. - Abstract: An alternative form of London’s electrodynamic theory of superconductors predicts that the electrostatic screening length is the same as the magnetic penetration depth. We argue that experiments performed to date do not rule out this alternative formulation and propose an experiment to test it. Experimental evidence in its favor would have fundamental implications for the understanding of superconductivity.
Space Environmental Testing of the Electrodynamic Dust Shield Technology
Calle, Carlos I.; Mackey, P. J.; Hogue, M. D.; Johansen, M .R.; Yim, H.; Delaune, P. B.; Clements, J. S.
2013-01-01
NASA's exploration missions to Mars and the moon may be jeopardized by dust that will adhere to surfaces of (a) Optical systems, viewports and solar panels, (b) Thermal radiators, (c) Instrumentation, and (d) Spacesuits. We have developed an active dust mitigation technology, the Electrodynamic Dust Shield, a multilayer coating that can remove dust and also prevents its accumulation Extensive testing in simulated laboratory environments and on a reduced gravity flight shows that high dust removal performance can be achieved Long duration exposure to the space environment as part of the MISSE-X payload will validate the technology for lunar missions.
Preliminary AD-Horn Thermomechanical and Electrodynamic Simulations
AUTHOR|(CDS)2095747; Horvath, David; Calviani, Marco
2016-01-01
As part of the Antiproton Decelerator (AD) target area consolidation activities planned for LS2, it has been necessary to perform a comprehensive study of the thermo-structural behaviour of the AD magnetic horn during operation, in order to detail specific requirements for the upgrade projects and testing procedures. The present work illustrates the preliminary results of the finite element analysis carried out to evaluate the thermal and structural behaviour of the device, as well as the methodology used to model and solve the thermomechanical and electrodynamic simulations performed in the AD magnetic horn.
Lectures on cosmology and action at a distance electrodynamics
Hoyle, Fred
1996-01-01
This book describes the subject of electrodynamics at classical as well as quantum level, developed as an interaction at a distance. Thus it has electric charges interacting with one another directly and not through the medium of a field. In general such an interaction travels forward and backward in time symmetrically, thus apparently violating the principle of causality. It turns out, however, that in such a description the cosmological boundary conditions become very important. The theory therefore works only in a cosmology with the right boundary conditions; but when it does work it is fre
Spin Pumping in Electrodynamically Coupled Magnon-Photon Systems.
Bai, Lihui; Harder, M; Chen, Y P; Fan, X; Xiao, J Q; Hu, C-M
2015-06-05
We use electrical detection, in combination with microwave transmission, to investigate both resonant and nonresonant magnon-photon coupling at room temperature. Spin pumping in a dynamically coupled magnon-photon system is found to be distinctly different from previous experiments. Characteristic coupling features such as modes anticrossing, linewidth evolution, peculiar line shape, and resonance broadening are systematically measured and consistently analyzed by a theoretical model set on the foundation of classical electrodynamic coupling. Our experimental and theoretical approach paves the way for pursuing microwave coherent manipulation of pure spin current via the combination of spin pumping and magnon-photon coupling.
Engineering electrodynamics electric machine, transformer, and power equipment design
Turowski, Janusz
2013-01-01
Due to a huge concentration of electromagnetic fields and eddy currents, large power equipment and systems are prone to crushing forces, overheating, and overloading. Luckily, power failures due to disturbances like these can be predicted and/or prevented.Based on the success of internationally acclaimed computer programs, such as the authors' own RNM-3D, Engineering Electrodynamics: Electric Machine, Transformer, and Power Equipment Design explains how to implement industry-proven modeling and design techniques to solve complex electromagnetic phenomena. Considering recent progress in magneti
Classical and quantum electrodynamics and the B(3) field
Evans, Myron W
2001-01-01
It is well known that classical electrodynamics is riddled with internal inconsistencies springing from the fact that it is a linear, Abelian theory in which the potentials are unphysical. This volume offers a self-consistent hypothesis which removes some of these problems, as well as builds a framework on which linear and nonlinear optics are treated as a non-Abelian gauge field theory based on the emergence of the fundamental magnetizing field of radiation, the B(3) field. Contents: Interaction of Electromagnetic Radiation with One Fermion; The Field Equations of Classical O (3) b Electrodyn
Long distance cell communication using spherical tether balloons
Manchanda, R. K.; Rajagopalan, Vasudevan; Vasudevan, Rajagopalan; Mehrotra, R. K.; Sreenivasan, S.; Pawaskar, M.; Subba Rao Jonnalagadda, Venkata; Buduru, Suneelkumar; Kulkarni, P. M.
A proof-of-concept experiment was conducted for long-range cell communication for rural tele-phony and internet. We designed and fabricated a spherical tether balloon to carry the con-ventional micro base transceiver station (BTS) along with three slotted antenna to cover 2-pi radius. AC power and optical fiber were anchored along with the tether line. A special fre-quency license was obtained from Wireless Planning Commission (WPC) wing of Department of Telecommunication (DoT), India for the period of experiment so as not to affect the opera-tional networks. The experiments were carried out for different BTS heights up to 500 meter. Signal measurement both in data mode and voice quality were done in different quadrant using mobile vans. This paper describes the methodology (under patenting) and utility of technique for operational application.
Tethered elevator: A unique opportunity for space processing
Monti, R.
1986-01-01
The latest fluid dynamic and material science experiments in the microgravity environment have emphasized the importance of the residual gravity level and of the g-jitter on fluid physics phenomena. The tethered elevator presents the possibility of providing variable g-levels (both steady and g-jitter) around a very low steady g-level (that can be realized when the elevator is near the center of mass of the space station-tether complex). When positioning a variable periodic oscillation to the payload a clean g-jitter disturbance can be obtained that would not be otherwise obtainable by other systems. These two possibilities make the elevator a facility to help resolve a number of still open questions that are preventing wider utilization of the space environment in the microgravity area.
Stability control of a flexible maneuverable tethered space net robot
Zhang, Fan; Huang, Panfeng
2018-04-01
As a promising solution for active space debris capture and removal, a maneuverable Tethered Space Net Robot (TSNR) is proposed as an improved Space Tethered Net (TSN). In addition to the advantages inherit to the TSN, the TSNR's maneuverability expands the capture's potential. However, oscillations caused by the TSNR's flexibility and elasticity of make higher requests of the control scheme. Based on the dynamics model, a modified adaptive super-twisting sliding mode control scheme is proposed in this paper for TSNR stability control. The proposed continuous control force can effectively suppress oscillations. Theoretical verification and numerical simulations demonstrate that the desired trajectory can be tracked steadily and efficiently by employing the proposed control scheme.
Synthesis and insertion chemistry of mixed tether uranium metallocene complexes
Energy Technology Data Exchange (ETDEWEB)
Siladke, Nathan A.; LeDuc, Jennifer; Ziller, Joseph W.; Evans, William J. [Department of Chemistry, University of California, Irvine, CA (United States)
2012-11-12
The synthesis of mixed tethered alkyl uranium metallocenes has been investigated by examining the reactivity of the bis(tethered alkyl) metallocene [(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}CH{sub 2}-κC){sub 2}U] (1) with substrates that react with only one of the U-C linkages. The effect of these mixed tether coordination environments on the reactivity of the remaining U-C bond has been studied by using CO insertion chemistry. One equivalent of azidoadamantane (AdN{sub 3}) reacts with 1 to yield the mixed tethered alkyl triazenido complex [(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}CH{sub 2}-κC)U(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}-CH{sub 2}NNN-Ad-κ{sup 2}N{sup 1,3})]. Similarly, a single equivalent of CS{sub 2} reacts with 1 to form the mixed tethered alkyl dithiocarboxylate complex [(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}CH{sub 2}-κC)U(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}- CH{sub 2}C(S){sub 2}-κ{sup 2}S,S{sup '})], a reaction that constitutes the first example of CS{sub 2} insertion into a U{sup 4+}-C bond. Complex 1 reacts with one equivalent of pyridine N-oxide by C-H bond activation of the pyridine ring to form a mixed tethered alkyl cyclometalated pyridine N-oxide complex [(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}CH{sub 2}-κC)(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 3})U(C{sub 6}H{sub 4}NO-κ{sup 2} C,O)]. The remaining (η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}CH{sub 2}-κC){sup 2-} ligand in each of these mixed tethered species show reactivity towards CO and tethered enolate ligands form by insertion. Subsequent rearrangement have been identified in [(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 3})U(C{sub 5}H{sub 4}NO-κ{sup 2}C,O)(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}C(=CH{sub 2})O- κO)] and [(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}CH{sub 2}NNN-Ad-κ{sup 2}N{sup 1,3})U(η{sup 5}-C{sub 5}Me{sub 4}SiMe{sub 2}C(=CH{sub 2})O-κO)]. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
A simplified tether model for molecular motor transporting cargo
International Nuclear Information System (INIS)
Fang-Zhen, Li; Li-Chun, Jiang
2010-01-01
Molecular motors are proteins or protein complexes which function as transporting engines in biological cells. This paper models the tether between motor and its cargo as a symmetric linear potential. Different from Elston and Peskin's work for which performance of the system was discussed only in some limiting cases, this study produces analytic solutions of the problem for general cases by simplifying the transport system into two physical states, which makes it possible to discuss the dynamics of the motor–cargo system in detail. It turns out that the tether strength between motor and cargo should be greater than a threshold or the motor will fail to transport the cargo, which was not discussed by former researchers yet. Value of the threshold depends on the diffusion coefficients of cargo and motor and also on the strength of the Brownian ratchets dragging the system. The threshold approaches a finite constant when the strength of the ratchet tends to infinity. (general)
Crowded, Confined, and Frustrated: Dynamics of Molecules Tethered to Nanoparticles
Agarwal, Praveen
2012-12-01
Above a critical chemistry-dependent molecular weight, all polymer molecules entangle and, as a result, exhibit slow dynamics, enhanced viscosity, and elasticity. Herein we report on the dynamics of low molecular weight polymers tethered to nanoparticles and find that even conventionally unentangled chains manifest dynamical features similar to entangled, long-chain molecules. Our findings are shown to imply that crowding and confinement of polymers on particles produce topological constraints analogous to those in entangled systems. © 2012 American Physical Society.
High-field MR imaging of tethered cord
International Nuclear Information System (INIS)
Sigal, R.; Bicetre, L.; Blass, C.; Doyon, D.; Pariente, D.
1986-01-01
MR imaging examinations of 12 patients with tethered cord syndrome have been performed on a 1.5-T MR imaging unit. Patients ranged in age from 3 to 60 years. MR findings were compared with those of myelography and metrizamide CT in all cases. Five patients underwent surgical control and postoperative MR imaging. Sagittal and axial sections were obtained using a spin-echo multisection, multiecho technique. T1-axial weighted images (SE 600/25) were sufficient to locate the position of the tip of the conus. They also allowed identification of extraspinal and intraspinal lipomas and clear-cut demarcation form associated tethered cord. Drawbacks of MR imaging were lack of precise depiction of the bone structures and the fact that clear identification of abnormal roots was problematic. The craniovertebral junction was always checked; two asymptomatic Chiari malformations were visualized. This study leads the authors to conclude that MR imaging should be used as the examination of first choice in the management of tethered cord syndrome
Results from a tethered rocket experiment (Charge-2)
Kawashima, N.; Sasaki, S.; Oyama, K. I.; Hirao, K.; Obayashi, T.; Raitt, W. J.; White, A. B.; Williamson, P. R.; Banks, P. M.; Sharp, W. F.
A tethered payload experiment (Charge-2) was carried out as an international program between Japan and the USA using a NASA sounding rocket at White Sands Missile Range. The objective of the experiment was to perform a new type of active experiment in space by injecting an electron beam from a mother-daughter rocket system connected with a long tether wire. The electron beam with voltage and current up to 1 kV and 80 mA (nominal) was injected from the mother payload. An insulated conductive wire of 426 m length connected the two payloads, the longest tether system flown so far. The electron gun system and diagnostic instruments (plasma, optical, particle and wave) functioned correctly throughout the flight. The potential rise of the mother payload during the electron beam emission was measured with respect to the daughter payload. The beam trajectory was detected by a camera onboard the mother rocket. Wave generation and current induction in the wire during the beam emission were also studied.
Structure of the vertex function in finite quantum electrodynamics
International Nuclear Information System (INIS)
Mannheim, P.D.
1975-01-01
We study the structure of the renormalized electromagnetic current vertes, GAMMA-tilde/sub μ/(p,p+q,q), in finite quantum electrodynamics. Using conformal invariance we find that GAMMA-tilde/sub μ/(p,p,0) takes the simple form of Z 1 γ/sub μ/ when the external fermions are far off the mass shell. We interpret this result as an old theorem on the structure of the vertex function due to Gell--Mann and Zachariasen. We give the general structure of the vertex for arbitrary momentum transfer parametrically, and discuss how the Bethe--Salpeter equation and the Federbush--Johnson theorem are satisfied. We contrast the meaning of pointlike in a finite field theory with the meaning understood in the parton model. We discuss to what extent the condition Z 1 = 0, which may hold in conformal theories other than finite quantum electrodynamics, may be interpreted as a bootstrap condition. We show that the vanishing of Z 1 prevents their being bound states in the Migdal--Polyakov bootstrap
Experimental Evaluation of Three Designs of Electrodynamic Flexural Transducers
Directory of Open Access Journals (Sweden)
Tobias J. R. Eriksson
2016-08-01
Full Text Available Three designs for electrodynamic flexural transducers (EDFT for air-coupled ultrasonics are presented and compared. An all-metal housing was used for robustness, which makes the designs more suitable for industrial applications. The housing is designed such that there is a thin metal plate at the front, with a fundamental flexural vibration mode at ∼50 kHz. By using a flexural resonance mode, good coupling to the load medium was achieved without the use of matching layers. The front radiating plate is actuated electrodynamically by a spiral coil inside the transducer, which produces an induced magnetic field when an AC current is applied to it. The transducers operate without the use of piezoelectric materials, which can simplify manufacturing and prolong the lifetime of the transducers, as well as open up possibilities for high-temperature applications. The results show that different designs perform best for the generation and reception of ultrasound. All three designs produced large acoustic pressure outputs, with a recorded sound pressure level (SPL above 120 dB at a 40 cm distance from the highest output transducer. The sensitivity of the transducers was low, however, with single shot signal-to-noise ratio ( SNR ≃ 15 dB in transmit–receive mode, with transmitter and receiver 40 cm apart.
Studies of nonlinear electrodynamics of high-temperature superconductors
International Nuclear Information System (INIS)
Lam, Q.H.
1991-01-01
Nonlinear electrodynamics of high-Tc superconductors are studied theoretically and experimentally. For powdered samples, a novel model is presented in which the metallographically observed superconducting grains in the powder are modeled as superconducting current loops of various areas with weak links. Surprising harmonic generation behavior in an ac field, H 1 cos(ωt), is predicted by the model; the power at high harmonics show sharp dips almost periodic in a super-posing dc magnetic field, revealing flux quantization in the prototype loops in the model. Such oscillation of the harmonic power in dc magnetic field, P nf (H dc ), is experimentally observed in powdered YBa 2 Cu 3 O 7 . For bulk sintered cylindrical samples, a generalized critical state model is presented. The nonlinear electrodynamics are due to flux-pinning. Experiments in ac and dc magnetic fields on a sintered cylindrical rod of YBa 2 Cu 3 O 7 yield unambiguous evidence of independent inter- and intragranular contributions to the complex harmonic permeability μ n = μ' n - iμ double-prime n . These data, together with P nf (H dc ), are explained quantitatively by the generalized critical state model, yielding a dependence on magnetic field of J c (H) ∼ H 02 local for the intergranular component, a steeper field dependence than for conventional type-II superconductors. Temperature-dependence measurements reveal that, while the intragranular supercurrents disappear at T c ≥ 91.2 K, the intergranular supercurrents disappear at T ≥ 86.6 K
Brain Electrodynamic and Hemodynamic Signatures Against Fatigue During Driving
Directory of Open Access Journals (Sweden)
Chun-Hsiang Chuang
2018-03-01
Full Text Available Fatigue is likely to be gradually cumulated in a prolonged and attention-demanding task that may adversely affect task performance. To address the brain dynamics during a driving task, this study recruited 16 subjects to participate in an event-related lane-departure driving experiment. Each subject was instructed to maintain attention and task performance throughout an hour-long driving experiment. The subjects' brain electrodynamics and hemodynamics were simultaneously recorded via 32-channel electroencephalography (EEG and 8-source/16-detector functional near-infrared spectroscopy (fNIRS. The behavior performance demonstrated that all subjects were able to promptly respond to lane-deviation events, even if the sign of fatigue arose in the brain, which suggests that the subjects were fighting fatigue during the driving experiment. The EEG event-related analysis showed strengthening alpha suppression in the occipital cortex, a common brain region of fatigue. Furthermore, we noted increasing oxygenated hemoglobin (HbO of the brain to fight driving fatigue in the frontal cortex, primary motor cortex, parieto-occipital cortex and supplementary motor area. In conclusion, the increasing neural activity and cortical activations were aimed at maintaining driving performance when fatigue emerged. The electrodynamic and hemodynamic signatures of fatigue fighting contribute to our understanding of the brain dynamics of driving fatigue and address driving safety issues through the maintenance of attention and behavioral performance.
Dispersion relations in quantum electrodynamics on the noncommutative Minkowski space
Energy Technology Data Exchange (ETDEWEB)
Zahn, J.W.
2006-12-15
We study field theories on the noncommutative Minkowski space with noncommuting time. The focus lies on dispersion relations in quantized interacting models in the Yang-Feldman formalism. In particular, we compute the two-point correlation function of the field strength in noncommutative quantum electrodynamics to second order. At this, we take into account the covariant coordinates that allow the construction of local gauge invariant quantities (observables). It turns out that this does not remove the well-known severe infrared problem, as one might have hoped. Instead, things become worse, since nonlocal divergences appear. We also show that these cancel in a supersymmetric version of the theory if the covariant coordinates are adjusted accordingly. Furthermore, we study the {phi}{sup 3} and the Wess-Zumino model and show that the distortion of the dispersion relations is moderate for parameters typical for the Higgs field. We also discuss the formulation of gauge theories on noncommutative spaces and study classical electrodynamics on the noncommutative Minkowski space using covariant coordinates. In particular, we compute the change of the speed of light due to nonlinear effects in the presence of a background field. Finally, we examine the so-called twist approach to quantum field theory on the noncommutative Minkowski space and point out some conceptual problems of this approach. (orig.)
Dispersion relations in quantum electrodynamics on the noncommutative Minkowski space
International Nuclear Information System (INIS)
Zahn, J.W.
2006-12-01
We study field theories on the noncommutative Minkowski space with noncommuting time. The focus lies on dispersion relations in quantized interacting models in the Yang-Feldman formalism. In particular, we compute the two-point correlation function of the field strength in noncommutative quantum electrodynamics to second order. At this, we take into account the covariant coordinates that allow the construction of local gauge invariant quantities (observables). It turns out that this does not remove the well-known severe infrared problem, as one might have hoped. Instead, things become worse, since nonlocal divergences appear. We also show that these cancel in a supersymmetric version of the theory if the covariant coordinates are adjusted accordingly. Furthermore, we study the Φ 3 and the Wess-Zumino model and show that the distortion of the dispersion relations is moderate for parameters typical for the Higgs field. We also discuss the formulation of gauge theories on noncommutative spaces and study classical electrodynamics on the noncommutative Minkowski space using covariant coordinates. In particular, we compute the change of the speed of light due to nonlinear effects in the presence of a background field. Finally, we examine the so-called twist approach to quantum field theory on the noncommutative Minkowski space and point out some conceptual problems of this approach. (orig.)
Electrodynamic modeling applied to micro-strip gas chambers
International Nuclear Information System (INIS)
Fang, R.
1998-01-01
Gas gain variations as functions of time, counting rate and substrate resistivity have been observed with Micro-Strip Gas Chambers (MSGC). Such a chamber is here treated as a system of 2 dielectrics, gas and substrate, with finite resistivities. Electric charging between their interface results in variations of the electric field and the gas gain. The electrodynamic equations (including time dependence) for such a system are proposed. A Rule of Charge Accumulation (RCA) is then derived which allows to determine the quantity and sign of charges accumulated on the surface at equilibrium. In order to apply the equations and the rule to MSGCs, a model of gas conductance induced by ionizing radiation is proposed, and a differential equation and some formulae are derived to calculate the rms dispersion and the spatial distribution of electrons (ions) in inhomogeneous electric fields. RCA coupled with a precise simulation of the electric fields gives the first quantitative explanation of gas gain variations of MSGCs. Finally an electrodynamic simulation program is made to reproduce the dynamic process of gain variation due to surface charging with an uncertainty of at most 15% relative to experimental data. As a consequence, the methods for stabilizing operation of MSGCs are proposed. (author)
Observers' measurements in premetric electrodynamics: Time and radar length
Gürlebeck, Norman; Pfeifer, Christian
2018-04-01
The description of an observer's measurement in general relativity and the standard model of particle physics is closely related to the spacetime metric. In order to understand and interpret measurements, which test the metric structure of the spacetime, like the classical Michelson-Morley, Ives-Stilwell, Kennedy-Thorndike experiments or frequency comparison experiments in general, it is necessary to describe them in theories, which go beyond the Lorentzian metric structure. However, this requires a description of an observer's measurement without relying on a metric. We provide such a description of an observer's measurement of the fundamental quantities time and length derived from a premetric perturbation of Maxwell's electrodynamics and a discussion on how these measurements influence classical relativistic observables like time dilation and length contraction. Most importantly, we find that the modification of electrodynamics influences the measurements at two instances: the propagation of light is altered as well as the observer's proper time normalization. When interpreting the results of a specific experiment, both effects cannot be disentangled, in general, and have to be taken into account.
Dynamic analysis of the tether transportation system using absolute nodal coordinate formulation
Sun, Xin; Xu, Ming; Zhong, Rui
2017-10-01
Long space tethers are becoming a rising concern as an alternate way for transportation in space. It benefits from fuel economizing. This paper focuses on the dynamics of the tether transportation system, which consists of two end satellites connected by a flexible tether, and a movable vehicle driven by the actuator carried by itself. The Absolute Nodal Coordinate Formulation is applied to the establishment of the equation of motion, so that the influence caused by the distributed mass and elasticity of the tether is introduced. Moreover, an approximated method for accelerating the calculation of the generalized gravitational forces on the tether is proposed by substituting the volume integral every step into summation of finite terms. Afterwards, dynamic evolutions of such a system in different configurations are illustrated using numerical simulations. The deflection of the tether and the trajectory of the crawler during the transportation is investigated. Finally, the effect on the orbit of the system due to the crawler is revealed.
International Nuclear Information System (INIS)
Lalanne, D.
1970-01-01
The experiment we have performed on the ACO (Orsay Collider Ring) is one of the most accurate tests of quantum electrodynamics over very short interaction distances (10 -14 cm). We have studied the electron-positron elastic scattering at very wide angle. This work is divided into 4 parts. The first part reviews recent tests of quantum electrodynamics and presents the electron-positron elastic scattering. The second part describes the measurement of brightness: the experimental device, data analysis and accuracy. The measurement of brightness has been performed by detecting the photons emitted in the double Bremsstrahlung reaction: e + e - → e + e - γγ. The third part deals with the measurement of the number of Bhabha events. The last part compares the experimental value of the Bhabha scattering with the theoretically expected value. We have got the following results: the number of Bhabha events: 757 events, the experimental value for Bhabha scattering cross-section: [1.97 ± 0.09 (stat.) ± 0.10 (syst.)]*10 -31 cm 2 . The comparison of this experimental value with the expected value has allowed us to set the lower limit of the cutting parameter Λ: Λ > 2 GeV
International Nuclear Information System (INIS)
Babson, J.F.
1989-01-01
The nineteen eighties has been a time in which Cosmology and Particle Physics have come together. This dissertation reflects that trend. It does so in two ways. First, in Chapters 1 through 3, there is a theoretical investigation into some aspects of generational universality. The consequences of a third lepton, namely the tauon, and an associated tau neutrino, are explored in terms of phenomenology (mass and V-A consistency) that may shed insight into questions of neutrino mass and increased symmetry at higher energies. Second, in Chapters 4 through 11, there is an experimental investigation in the form of constructing and operating the first stage of the DUMAND (Deep Underwater Muon and Neutrino Detection) project which was a ship suspended muon and neutrino telescope called the SPS (Short Prototype String). This detector is of the water Cherenkov type and is the first time such an instrument has been successfully built and tested for use in the ocean. Chapters 6 through 10 are devoted to the detailed documentation of the parts of the SPS and its technology integration that I designed, prototyped, and debugged. In particular, a complete description is given to the command and control communications system of the string, the digital control electronics and associated software for the Optical, Calibration, and Power modules as well as the fast digitizing electronics or String Bottom Controller (SBC). This includes the development of a microcontroller language UHPS (Underwater Hawai'i Programming System). Finally, Chapter 11 is an analysis of SPS data in terms of ascertaining a purely statistically based downward traveling muon rate at a depth of 4.0 Km yielding (2.06 ± 0.68) x 10 -2 Hz
1986-01-01
Several key concepts of the science and applications tethered platforms were studied. Some conclusions reached are herein listed. Tether elevator and platform could improve the space station scientific and applicative capabilities. The space elevator presents unique characteristics as microgravity facility and as a tethered platform servicing vehicle. Pointing platforms could represent a new kind of observation facility for large class of payloads. The dynamical, control and technological complexity of these concepts advised demonstrative experiments. The on-going tethered satellite system offers the opportunity to perform such experiments. And feasibility studies are in progress.
Dynamics Model for a Multi-Tethered Space-Based Interferometer
National Research Council Canada - National Science Library
Gates, Stephen
2000-01-01
.... Tether constitutive behavior is discussed. Prescribed motion of any system degrees of freedom is treated, and expressions for the corresponding constraint force/torque components are established.
A Fiber-Optic Tether for the Hull Search UUV System Documentation
National Research Council Canada - National Science Library
Buescher, J. G
2006-01-01
...) conducting ship hull inspection missions, defines the required specifications that will allow the integration and installation of a FO tether system on UUVs with ship hull inspection capability...
Filla, Nicholas; Ramasamy, Ramaraja; Wang, Xianqiao
2018-04-25
The strength and nature of the interactions between carbon nanotubes (CNTs) and molecular tethers plays a vital role in technology such as CNT-enzyme sensors. Tethers that attach noncovalently to CNTs are ideal for retaining the electrical properties of the CNTs since they do not degrade the CNT surface and effect its electrical conductivity. However, leaching due to weak CNT-tether attachment is very common when using noncovalent tethers, and this has limited their use in commercial products including biosensors. Thus, understanding the fundamental mechanics governing the strength of CNT-tether adhesion is crucial for the design of highly sensitive, viable sensors. Here, we computationally investigate the adhesion strength of CNT-tether complexes with 8 different tethering molecules designed to adhere noncovalently to the CNT surface. We study the effects of CNT diameter, CNT chirality, and the size/geometry of the tethering molecule on the adhesion energy and force. Our results show an asymptotic relationship between adhesion strength and CNT diameter. Calculations show that noncovalent tethers tested here can reach adhesion forces and energies that are up to 21% and 54% of the strength of the carbon-carbon single bond force and bond energy respectively. We anticipate our results will help guide CNT-enzyme sensor design to produce sensors with high sensitivity and minimal leaching.
Energy Technology Data Exchange (ETDEWEB)
Gu, Beom W.; Choi, Su Y.; Rim, Chun T. [Dept. of Nuclear and Quantum Engineering, KAIST, Daejeon (Korea, Republic of); Choi, Young Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Cai, Guowei; Seneviratne, Lakmal [Dept. of Aerospace Engineering, Khalifa University, Abu Dhabi (United Arab Emirates)
2016-08-15
In this paper, new tethered aerial robots including roaming tethered aerial robots (RTARs) for radioactive material sampling and stationary tethered aerial robots (STARs) for environment monitoring are proposed to meet extremely-long-endurance missions of nuclear power plants. The flight of the proposed tethered aerial robots may last for a few days or even a few months as long as the tethered cable provides continuous power. A high voltage AC or DC power system was newly adopted to reduce the mass of the tethered cable. The RTAR uses a tethered cable spooled from the aerial robot and an aerial tension control system. The aerial tension control system provides the appropriate tension to the tethered cable, which is accordingly laid down on the ground as the RTAR roams. The STAR includes a tethered cable spooled from the ground and a ground tension control system, which enables the STAR to reach high altitudes. Prototypes of the RTAR and STAR were designed and successfully demonstrated in outdoor environments, where the load power, power type, operating frequency, and flight attitude of the RTAR and STAR were: 180 W, AC 100 kHz, and 20 m; and 300 W, AC or DC 100 kHz, and 80 m, respectively.
Directory of Open Access Journals (Sweden)
Beom W. Gu
2016-08-01
Full Text Available In this paper, new tethered aerial robots including roaming tethered aerial robots (RTARs for radioactive material sampling and stationary tethered aerial robots (STARs for environment monitoring are proposed to meet extremely-long-endurance missions of nuclear power plants. The flight of the proposed tethered aerial robots may last for a few days or even a few months as long as the tethered cable provides continuous power. A high voltage AC or DC power system was newly adopted to reduce the mass of the tethered cable. The RTAR uses a tethered cable spooled from the aerial robot and an aerial tension control system. The aerial tension control system provides the appropriate tension to the tethered cable, which is accordingly laid down on the ground as the RTAR roams. The STAR includes a tethered cable spooled from the ground and a ground tension control system, which enables the STAR to reach high altitudes. Prototypes of the RTAR and STAR were designed and successfully demonstrated in outdoor environments, where the load power, power type, operating frequency, and flight attitude of the RTAR and STAR were: 180 W, AC 100 kHz, and 20 m; and 300 W, AC or DC 100 kHz, and 80 m, respectively.
The new topological sectors associated with quantum electrodynamics
International Nuclear Information System (INIS)
Marino, E.C.
1994-01-01
A formulation of Quantum Electrodynamics in terms of an antisymmetric-tensor gauge field is presented. In this formulation the topological current of this field appears as a source for the electromagnetic field and the topological charge therefore acts physically as an electric charge. These nontrivial, electrically charged, sectors contain massless states orthogonal to the vacuum which are created by a gauge invariant operator can be interpreted as coherent states of photons. The new states do interact with the charged states of QCD in the usual way. It is argued that if these new sectors are in fact realized in nature then a very intense background electromagnetic field is necessary for the experimental observation of them. The order of magnitude of the intensity threshold is presented. (author). 2 refs
Computational electrodynamics the finite-difference time-domain method
Taflove, Allen
2005-01-01
This extensively revised and expanded third edition of the Artech House bestseller, Computational Electrodynamics: The Finite-Difference Time-Domain Method, offers engineers the most up-to-date and definitive resource on this critical method for solving Maxwell's equations. The method helps practitioners design antennas, wireless communications devices, high-speed digital and microwave circuits, and integrated optical devices with unsurpassed efficiency. There has been considerable advancement in FDTD computational technology over the past few years, and the third edition brings professionals the very latest details with entirely new chapters on important techniques, major updates on key topics, and new discussions on emerging areas such as nanophotonics. What's more, to supplement the third edition, the authors have created a Web site with solutions to problems, downloadable graphics and videos, and updates, making this new edition the ideal textbook on the subject as well.
Discrete geometry: speculations on a new framework for classical electrodynamics
International Nuclear Information System (INIS)
Hemion, G.
1988-01-01
An attempt is made to describe the basic principles of physics in terms of discrete partially ordered sets. Geometric ideas are introduced by means of an action at a distance formulation of classical electrodynamics. The speculations are in two main directions: (i) Gravity, one of the four elementary forces of nature, seems to be fundamentally different from the other three forces. Could it be that gravity can be explained as a natural consequence of the discrete structure? (ii) The problem of the observer in quantum mechanics continues to cause conceptual problems. Can quantum statistics be explained in terms of finite ensembles of possible partially ordered sets? The development is guided at all stages by reference to the simplest, and most well-established principles of physics
Axiomatic field theory and quantum electrodynamics: the massive case
International Nuclear Information System (INIS)
Steinmann, O.
1975-01-01
Massive quantum electrodynamics of the electron is formulated as an LSZ theory of the electromagnetic field F(μν) and the electron-positron fields PSI. The interaction is introduced with the help of mathematically well defined subsidiary conditions. These are: 1) gauge invariance of the first kind, assumed to be generated by a conserved current j(μ); 2) the homogeneous Maxwell equations and a massive version of the inhomogeneous Maxwell equations; 3) a minimality condition concerning the high momentum behaviour of the theory. The inhomogeneous Maxwell equation is a linear differential equation connecting Fsub(μν) with the current Jsub(μ). No Lagrangian, no non-linear field equations, and no explicit expression of Jsub(μ) in terms of PSI, anti-PSI are needed. It is shown in perturbation theory that the proposed conditions fix the physically relevant (i.e. observable) quantities of the theory uniquely
Numerical Analysis for Dynamic Instability of Electrodynamic Maglev Systems
Directory of Open Access Journals (Sweden)
Y. Cai
1995-01-01
Full Text Available Suspension instabilities in an electrodynamic maglev system with three- and five-degrees-of-freedom DOF vehicles traveling on a double L-shaped set of guideway conductors were investigated with various experimentally measured magnetic force data incorporated into theoretical models. Divergence and flutter were obtained from both analytical and numerical solutions for coupled vibration of the three-DOF maglev vehicle model. Instabilities of five direction motion (heave, slip, roll, pitch, and yaw were observed for the five-DOF vehicle model. The results demonstrate that system parameters such as system damping, vehicle geometry, and coupling effects among five different motions play very important roles in the occurrence of dynamic instabilities of maglev vehicles.
Digital Quantum Simulation of Spin Models with Circuit Quantum Electrodynamics
Directory of Open Access Journals (Sweden)
Y. Salathé
2015-06-01
Full Text Available Systems of interacting quantum spins show a rich spectrum of quantum phases and display interesting many-body dynamics. Computing characteristics of even small systems on conventional computers poses significant challenges. A quantum simulator has the potential to outperform standard computers in calculating the evolution of complex quantum systems. Here, we perform a digital quantum simulation of the paradigmatic Heisenberg and Ising interacting spin models using a two transmon-qubit circuit quantum electrodynamics setup. We make use of the exchange interaction naturally present in the simulator to construct a digital decomposition of the model-specific evolution and extract its full dynamics. This approach is universal and efficient, employing only resources that are polynomial in the number of spins, and indicates a path towards the controlled simulation of general spin dynamics in superconducting qubit platforms.
Higgs-Like Particle due to Revised Quantum Electrodynamics
Directory of Open Access Journals (Sweden)
Lehnert B.
2013-07-01
Full Text Available A Higgs-like particle having zero net electric charge, zero spin, and a nonzero rest mass can be deduced from an earlier elaborated revised quantum electrodynamical theory which is based on linear symmetry breaking through a nonzero electric ﬁeld divergence in the vacuum state. This special particle is obtained from a composite longitudinal solution based on a zero magnetic ﬁeld strength and on a nonzero divergence but a vanishing curl of the electric ﬁeld strength. The present theory further diﬀers from that of the nonlinear spontaneously broken symmetry by Higgs, in which elementary particles obtain their masses through an interaction with the Higgs ﬁeld. An experimental proof of the basic features of a Higgs-like particle thus supports the present theory, but does not for certain conﬁrm the process which would generate massive particles through a Higgs ﬁeld
Cavity quantum electrodynamics with Anderson-localized modes
DEFF Research Database (Denmark)
Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren
2010-01-01
by a factor of 15 on resonance with the Anderson-localized mode, and 94% of the emitted single photons coupled to the mode. Disordered photonic media thus provide an efficient platform for quantum electrodynamics, offering an approach to inherently disorder-robust quantum information devices.......A major challenge in quantum optics and quantum information technology is to enhance the interaction between single photons and single quantum emitters. This requires highly engineered optical cavities that are inherently sensitive to fabrication imperfections. We have demonstrated a fundamentally...... different approach in which disorder is used as a resource rather than a nuisance. We generated strongly confined Anderson-localized cavity modes by deliberately adding disorder to photonic crystal waveguides. The emission rate of a semiconductor quantum dot embedded in the waveguide was enhanced...
Measurement of wall thickness with electrodynamic test heads
International Nuclear Information System (INIS)
Koch, R.; Maurer, A.
1993-01-01
Starting from the boundary conditions fixed by the physical properties of the electromagnetic/acoustic conversion and the operating limits which result from these for the sensors used, the use of electro-dynamic ultrasonic transducers for measuring wall thickness and double checks in plants for automatic production inspection and production control is shown. The sensor itself is the heart of a test system, but only the equipment and plant concepts surrounding the sensor make economic solution of the test problem possible. The quality of the signals which are supplied by a sensor, determines the quality of a test system. This can only be achieved by optimising all parts of a complex automatic test rig, such as the test head, mechanics, electronics and evaluation for the test problem concerned. (orig./HP) [de
Towards measuring quantum electrodynamic torque with a levitated nanorod
Xu, Zhujing; Bang, Jaehoon; Ahn, Jonghoon; Hoang, Thai M.; Li, Tongcang
2017-04-01
According to quantum electrodynamics, quantum fluctuations of electromagnetic fields give rise to a zero-point energy that never vanishes, even in the absence of electromagnetic sources. The interaction energy will not only lead to the well-known Casimir force but will also contribute to the Casimir torque for anisotropic materials. We propose to use an optically levitated nanorod in vacuum and a birefringent substrate to experimentally investigate the QED torque. We have previously observed the libration of an optically levitated non-spherical nanoparticle in vacuum and found it to be an ultrasensitive torque sensor. A nanorod with a long axis of 300nm and a diameter of 60nm levitated in vacuum at 10 (- 8) torr will have a remarkable torque detection sensitivity on the order of 10 (- 28) Nm/ √Hz, which will be sufficient to detect the Casimir torque. This work is partially supported by the National Science Foundation under Grant No.1555035-PHY.
Hydrodynamic view of electrodynamics: energy rays and electromagnetic effective stress
International Nuclear Information System (INIS)
Chou, Chia-Chun; Wyatt, Robert E
2011-01-01
Energy rays ('photon trajectories') based upon the hydrodynamic formulation of electrodynamics are presented for time-dependent electromagnetic wave propagation. We derive Cauchy's equation of motion for the electromagnetic effective force governing the dynamics of energy rays. The effective force generated by the electromagnetic effective stress provides a surface force acting on the energy fluid element. For the head-on collision of two electromagnetic Gaussian pulses, the electromagnetic effective force, analogous to the role played by the quantum force in Bohmian mechanics, guides these non-crossing energy rays. For an electromagnetic pulse traveling from free space to a dielectric medium, the energy rays guided by the electromagnetic effective stress display reflection and refraction at the interface.
A Uniﬁed Theory of Interaction: Gravitation and Electrodynamics
Directory of Open Access Journals (Sweden)
Wagener P.
2008-10-01
Full Text Available A theory is proposed from which the basic equations of gravitation and electromagnetism are derived from a single Lagrangian. The total energy of an atom can be expressed in a power series of the fine structure constant, $alpha$. Specific selections of these terms yield the relativistic correction to the Bohr values of the hydrogen spectrum and the Sommerfeld-Dirac equation for the fine structure spectrum of the hydrogen atom. Expressions for the classical electron radius and some of the Large Number Coincidences are derived. A Lorentz-type force equation is derived for both gravitation and electrodynamics. Electron spin is shown to be an effect of fourth order in $alpha$.
Black hole solution in the framework of arctan-electrodynamics
Kruglov, S. I.
An arctan-electrodynamics coupled with the gravitational field is investigated. We obtain the regular black hole solution that at r →∞ gives corrections to the Reissner-Nordström solution. The corrections to Coulomb’s law at r →∞ are found. We evaluate the mass of the black hole that is a function of the dimensional parameter β introduced in the model. The magnetically charged black hole was investigated and we have obtained the magnetic mass of the black hole and the metric function at r →∞. The regular black hole solution is obtained at r → 0 with the de Sitter core. We show that there is no singularity of the Ricci scalar for electrically and magnetically charged black holes. Restrictions on the electric and magnetic fields are found that follow from the requirement of the absence of superluminal sound speed and the requirement of a classical stability.
Infra-red finiteness in quantum electro-dynamics
International Nuclear Information System (INIS)
Kawai, Takahiro
1984-01-01
The authors report some mathematical aspects of a recent solution of the infra-red catastrophe in quantum electro-dynamics. A principal result is that the coordinate space Feynman function can be separated into two factors the first of which is a unitary operator in photon space representing the classical electro-magnetic contribution to the amplitude, and the second of which is a residual factor representing the quantum fluctuation about the classical contribution. The main objectives were to verify: (i) the residual factor is free of infra-red divergences, and (ii) the dominant part of the singularity of the residual factor on the positive-α Landau surface has the same analytic form as it would have if the photons were massive. (Auth.)
Rotating Dilaton Black Strings Coupled to Exponential Nonlinear Electrodynamics
Directory of Open Access Journals (Sweden)
Ahmad Sheykhi
2014-01-01
Full Text Available We construct a new class of charged rotating black string solutions coupled to dilaton and exponential nonlinear electrodynamic fields with cylindrical or toroidal horizons in the presence of a Liouville-type potential for the dilaton field. Due to the presence of the dilaton field, the asymptotic behaviors of these solutions are neither flat nor (AdS. We analyze the physical properties of the solutions in detail. We compute the conserved and thermodynamic quantities of the solutions and verify the first law of thermodynamics on the black string horizon. When the nonlinear parameter β2 goes to infinity, our results reduce to those of black string solutions in Einstein-Maxwell-dilaton gravity.
New technical solutions of using rolling stock electrodynamical braking
Directory of Open Access Journals (Sweden)
Leonas Povilas LINGAITIS
2009-01-01
Full Text Available The paper considers some theoretical and practical problems associated with the use of traction motor are operating in the generator mode (in braking. Mathematical and graphical relationships of electrodynamic braking, taking into account the requirements raised to braking systems in rail transport are presented. The latter include discontinuity of braking process, braking force regulation, depending on the locomotive speed, mass, type of railway and other parameters. Schematic diagrams of the locomotive braking and ways of controlling the braking force by varying electric circuit parameters are presented. The authors suggested contact-free regulation method of braking resistor for controlling braking force in rheostatic braking, and resistor parameters regulate with pulse regulation mode by semiconductor devices, such as new electrical components for rolling stock – IGBT transistors operating in the key mode. Presenting energy savings power systems, which are using regenerative braking-returning energy and diesel engine or any form of hybrid traction vehicles systems, circuit diagrams, electrical parameters curves.
Special relativity, electrodynamics, and general relativity from Newton to Einstein
Kogut, John B
2018-01-01
Special Relativity, Electrodynamics and General Relativity: From Newton to Einstein, Second Edition, is intended to teach (astro)physics, astronomy, and cosmology students how to think about special and general relativity in a fundamental, but accessible, way. Designed to render any reader a "master of relativity," everything on the subject is comprehensible and derivable from first principles. The book emphasizes problem solving, contains abundant problem sets, and is conveniently organized to meet the needs of both student and instructor. Fully revised, updated and expanded second edition Includes new chapters on magnetism as a consequence of relativity and electromagnetism Contains many improved and more engaging figures Uses less algebra resulting in more efficient derivations Enlarged discussion of dynamics and the relativistic version of Newton's second law
Entangling distant resonant exchange qubits via circuit quantum electrodynamics
Srinivasa, V.; Taylor, J. M.; Tahan, Charles
2016-11-01
We investigate a hybrid quantum system consisting of spatially separated resonant exchange qubits, defined in three-electron semiconductor triple quantum dots, that are coupled via a superconducting transmission line resonator. Drawing on methods from circuit quantum electrodynamics and Hartmann-Hahn double resonance techniques, we analyze three specific approaches for implementing resonator-mediated two-qubit entangling gates in both dispersive and resonant regimes of interaction. We calculate entangling gate fidelities as well as the rate of relaxation via phonons for resonant exchange qubits in silicon triple dots and show that such an implementation is particularly well suited to achieving the strong coupling regime. Our approach combines the favorable coherence properties of encoded spin qubits in silicon with the rapid and robust long-range entanglement provided by circuit QED systems.
Operator's Manual for SHEBA Powered Tether Balloon System
Lappen, Cara-Lyn; Randall, David A.
1998-01-01
The Surface Heat and Energy Budget of the Arctic (SHEBA) was an intensive field project which took place in the Arctic Ocean from October 1997 through October 1998. Its purpose was to measure as many facets of the Arctic environment as possible so that we would be able to better understand the interaction between the ice, atmosphere, and ocean and their interactions with global climate. One aspect of the atmospheric field component was launching tethered balloons to monitor the profiles of temperature, wind, pressure, and humidity, as well as examine the vertical structure of cloud droplet sizes and distributions. The tethered balloon that we used was one specially designed for use in freezing climates by SPEC Corporation in Boulder, Colorado. A special winch that was able to withstand Arctic temperature and weather became necessary when the testing of simple winch systems used in warmer climates failed under these extreme conditions. The purpose of this manual is to acquaint any new user to the powered tethered balloon system deployed at the The Surface Heat and Energy Budget of the Arctic (SHEBA ice camp. It includes a description of the preparations necessary to get ready for a launch, the mechanics of the actual launch, and an account of the proper procedure for taking down the equipment when finished. It will also include tips on how to minimize potential equipment failures, some trouble shooting, and some safety ideas. This manual is designed so that new operators can use the system with minimal previous training. At the end of this manual, the reader will find a quick checklist.
Cavity quantum electrodynamics in application to plasmonics and metamaterials
Directory of Open Access Journals (Sweden)
Pavel Ginzburg
2016-11-01
Full Text Available Frontier quantum engineering tasks require reliable control over light-matter interaction dynamics, which could be obtained by introducing electromagnetic structuring. Initiated by the Purcell's discovery of spontaneous emission acceleration in a cavity, the concept of electromagnetic modes' design have gained a considerable amount of attention due to development of photonic crystals, micro-resonators, plasmonic nanostructures and metamaterials. Those approaches, however, offer qualitatively different strategies for tailoring light-matter interactions and are based on either high quality factor modes shaping, near field control, or both. Remarkably, rigorous quantum mechanical description might address those processes in a different fashion. While traditional cavity quantum electrodynamics tools are commonly based on mode decomposition approach, few challenges rise once dispersive and lossy nanostructures, such as noble metals (plasmonic antennas or metamaterials, are involved. The primary objective of this review is to introduce key methods and techniques while aiming to obtain comprehensive quantum mechanical description of spontaneous, stimulated and higher order emission and interaction processes, tailored by nanostructured material environment. The main challenge and the complexity here are set by the level of rigorousity, up to which materials should be treated. While relatively big nanostructured features (10nm and larger could be addressed by applying fluctuation–dissipation theorem and corresponding Green functions' analysis, smaller objects will require individual approach. Effects of material granularity, spatial dispersion, tunneling over small gaps, material memory and others will be reviewed. Quantum phenomena, inspired and tailored by nanostructured environment, plays a key role in development of quantum information devices and related technologies. Rigorous analysis is required for both examination of experimental observations
Macroscopic quantum electrodynamics of high-Q cavities
International Nuclear Information System (INIS)
Khanbekyan, Mikayel
2009-01-01
In this thesis macroscopic quantum electrodynamics in linear media was applied in order to develop an universally valid quantum theory for the description of the interaction of the electromagnetic field with atomic sources in high-Q cavities. In this theory a complete description of the characteristics of the emitted radiation is given. The theory allows to show the limits of the applicability of the usually applied theory. In order to establish an as possible generally valid theory first the atom-field interaction was studied in the framework of macroscopic quantum electrodynamics in dispersive and absorptive media. In order to describe the electromagnetic field from Maxwell's equations was started, whereby the noise-current densities, which are connected with the absorption of the medium, were included. The solution of these equations expresses the electromagnetic field variables by the noise-current densities by means of Green's tensor of the macroscopic Maxwell equations. The explicit quantization is performed by means of the noise-current densities, whereby a diagonal Hamiltonian is introduced, which then guarantees the time development according to Maxwell's equation and the fulfillment of the fundamental simultaneous commutation relations of the field variables. In the case of the interaction of the medium-supported field with atoms the Hamiltonian must be extended by atom-field interactions energies, whereby the canonical coupling schemes of the minimal or multipolar coupling can be used. The dieelectric properties of the material bodies as well as their shape are coded in the Green tensor of the macroscopic Maxwell equations. As preparing step first the Green tensor was specified in order to derive three-dimensional input-output relations for the electromagnetic field operators on a plane multilayer structure. Such a general dewscription of the electromagnetic field allows the inclusion both of dispersion and absorption of the media and the possible
Tethered Transition Metals Promoted Photocatalytic System for Efficient Hydrogen Evolutions
Takanabe, Kazuhiro; Isimjan, Tayirjan; Yu, Weili; Del Gobbo, Silvano; Xu, Wei
2015-01-01
The present invention is directed, at least in part, to a process for improving the efficiency of a photocatalyst (a semiconductor photocatalyst) by tethering (depositing) a metal (e.g., metal ions of a late transition metal, such as nickel) to the semiconductor (photocatalyst) surface through the use of an organic ligand. More specifically, 1,2-ethanedithiol (EDT) functions as an excellent molecular linker (organic ligand) to attach a transition metal complex (e.g., nickel (Ni.sup.2+ ions)) to the semiconductor surface, which can be in the form of a cadmium sulfide surface. The photocatalyst has particular utility in generating hydrogen from H.sub.2S.
Tethered Transition Metals Promoted Photocatalytic System for Efficient Hydrogen Evolutions
Takanabe, Kazuhiro
2015-03-05
The present invention is directed, at least in part, to a process for improving the efficiency of a photocatalyst (a semiconductor photocatalyst) by tethering (depositing) a metal (e.g., metal ions of a late transition metal, such as nickel) to the semiconductor (photocatalyst) surface through the use of an organic ligand. More specifically, 1,2-ethanedithiol (EDT) functions as an excellent molecular linker (organic ligand) to attach a transition metal complex (e.g., nickel (Ni.sup.2+ ions)) to the semiconductor surface, which can be in the form of a cadmium sulfide surface. The photocatalyst has particular utility in generating hydrogen from H.sub.2S.
Fullerenic structures and such structures tethered to carbon materials
Goel, Anish; Howard, Jack B.; Vander Sande, John B.
2010-01-05
The fullerenic structures include fullerenes having molecular weights less than that of C.sub.60 with the exception of C.sub.36 and fullerenes having molecular weights greater than C.sub.60. Examples include fullerenes C.sub.50, C.sub.58, C.sub.130, and C.sub.176. Fullerenic structure chemically bonded to a carbon surface is also disclosed along with a method for tethering fullerenes to a carbon material. The method includes adding functionalized fullerene to a liquid suspension containing carbon material, drying the suspension to produce a powder, and heat treating the powder.
A tethered balloon system for observation of atmospheric temperature inversion
International Nuclear Information System (INIS)
Hayashi, Takashi; Kakuta, Michio
1979-05-01
In environmental assessment of near-shore nuclear plants, information is often required on the development of internal boundary layer (IBL) and associated fumigation condition. Single tower data is not sufficient to clarify the site-dependent IBL structure that affects the atmospheric diffusion in shoreline-stack-site boundary complex. A tethered balloon system has been developed, which comprises a fixed point kitoon and a car-borne small balloon. The system enables us to measure the detailed time-space distribution of temperature without much man-power. The system and example of field observations with it are described. (author)
Directory of Open Access Journals (Sweden)
Wei Hong eToh
2016-02-01
Full Text Available Membrane tethers have been identified throughout different compartments of the endomembrane system. It is now well established that a number of membrane tethers mediate docking of membrane carriers in anterograde and retrograde transport and in regulating the organization of membrane compartments. Much of our information on membrane tethers have been obtained from the analysis of individual membrane tethers in cultured cells. In the future it will be important to better appreciate the network of interactions mediated by tethers and the potential co-ordination of their collective functions in vivo. There are now a number of studies which have analyzed membrane tethers in tissues and organisms which are providing new insights into the role of this class of membrane protein at the physiological level. Here we review recent advances in the understanding of the function of membrane tethers from knock outs (or knock downs in whole organisms and from mutations in tethers associated with disease.
Acquisition of Ice-Tethered Profilers with Velocity (ITP-V) Instruments for Future Arctic Studies
2016-11-15
San Diego, CA, IEEE Xplore . Toole, J. M., R. A. Krishfield, M.-L. Timmennans, and A. Proshutinsky, 2011: The Ice-Tethered Profiler: Argo ofthe Arctic, Oceanogr., 24, 126-135. 4 ...observations from Ice-Tethered Profilers, MTS/ IEEE Oceans’ 2015, Washington DC, 1-10. Krishfield, R., J. Toole, A. Proshutinsky, and M.-L. Timmennans, 2008
Keiichiro Hara; Kazuo Osada; Takashi Yamanouchi
2007-01-01
The 46th Japanese Antarctic Research Expedition (JARE-46) carried out twenty seven tethered-balloon-borne aerosol measurements at Syowa Station for better understanding of aerosol chemical and physical properties in the lower troposphere from 6th January 2005 until 11 December 2005. This report summarizes the plan, preparation, field activities and some troubles/problems in the tethered-balloon observations.
Tethered spinal cord: the effect of neurosurgery on the lower urinary tract and male sexual function
Boemers, T. M.; van Gool, J. D.; de Jong, T. P.
1995-01-01
To determine the effect of neurosurgical untethering on the lower urinary tract and male sexual function, in patients with tethered spinal cord. Thirty-six children with tethered spinal cord due to neurospinal dysraphism were assessed clinically and urodynamically before and after surgical
Cholesterol tethered bioresponsive polycation as a candidate for gene delivery
Energy Technology Data Exchange (ETDEWEB)
Zhu Ying [Second Affiliated Hospital, Medical College, Zhejiang University, Hangzhou 310009 (China); Wang Youxiang, E-mail: yx_wang@zju.edu.cn [Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Key Laboratory of Macromolecular Synthesis and Functionalization, Ministry of Education, Zhejiang University, Hangzhou 310027 (China); Hu Qiaoling; Shen Jiacong [Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Key Laboratory of Macromolecular Synthesis and Functionalization, Ministry of Education, Zhejiang University, Hangzhou 310027 (China)
2009-04-30
The efficient unpacking of viral protein shell gave the inspiration for the synthesized vectors. In this research, novel cholesterol tethered bioresponsive polyethylenimine (PEI) was specially designed via disulfide-containing cross-linker. The cholesterol lipid had proved to increase the permeability of gene vector through cell membrane. The acid-base titration indicated that the synthesized polycation possessed efficient proton sponge effect, which was suggested to increase endosomal release of pDNA complexes into the cytoplasm. The cholesterol tethered polycation could effectively induce DNA condensation and form spherical particles with diameter about 200 nm at N/P ratio of 10. At glutathione concentration of 3 mM, the polyplexes were unpacked due to the bioresponsive cleavage of the disulfide bonds. The in-vitro experiment indicated that the polyplexes showed efficient transfection efficiency to HEK293T cells. All the results indicated that the bioresponsive polycation could be served as an effective trigger to control the release of DNA at the intracellular environment. The novel bioresponsive polycation might have great potential in non-viral gene delivery research and application.
Piperidinium tethered nanoparticle-hybrid electrolyte for lithium metal batteries
Korf, Kevin S.
2014-06-23
We report on the synthesis of novel piperidinium-based ionic liquid tethered nanoparticle hybrid electrolytes and investigate their physical and electrochemical properties. Hybrid electrolytes based on the ionic liquid 1-methyl-1-propylpiperidinium bis(trifluoromethanesulfone) imide covalently tethered to silica nanoparticles (SiO2-PP-TFSI) were blended with propylene carbonate-1 M lithium bis(trifluoromethanesulfone) imide (LiTFSI). We employed NMR analysis to confirm the successful creation of the hybrid material. Dielectric and rheological measurements show that these electrolytes exhibit exceptional room-temperature DC ionic conductivity (10-2 to 10 -3 S cm-1) as well as high shear mechanical moduli (105 to 106 Pa). Lithium transference numbers were found to increase with particle loading and to reach values as high as 0.22 at high particle loadings where the particle jam to form a soft glassy elastic medium. Analysis of lithium electrodeposits obtained in the hybrid electrolytes using SEM and EDX spectra show that the SiO2-PP-TFSI nanoparticles are able to smooth lithium deposition and inhibit lithium dendrite proliferation in Li metal batteries. LTOSiO2-PP-TFSI/PC in 1 M LiTFSILi half-cells based on the SiO2-PP-TFSI hybrid electrolytes exhibit attractive voltage profiles and trouble-free extended cycling behavior over more than 1000 cycles of charge and discharge. This journal is © the Partner Organisations 2014.
Isothermal pumping analysis for high-altitude tethered balloons.
Kuo, Kirsty A; Hunt, Hugh E M
2015-06-01
High-altitude tethered balloons have potential applications in communications, surveillance, meteorological observations and climate engineering. To maintain balloon buoyancy, power fuel cells and perturb atmospheric conditions, fluids could be pumped from ground level to altitude using the tether as a hose. This paper examines the pumping requirements of such a delivery system. Cases considered include delivery of hydrogen, sulfur dioxide (SO2) and powders as fluid-based slurries. Isothermal analysis is used to determine the variation of pressures and velocities along the pipe length. Results show that transport of small quantities of hydrogen to power fuel cells and maintain balloon buoyancy can be achieved at pressures and temperatures that are tolerable in terms of both the pipe strength and the current state of pumping technologies. To avoid solidification, transport of SO2 would require elevated temperatures that cannot be tolerated by the strength fibres in the pipe. While the use of particle-based slurries rather than SO2 for climate engineering can reduce the pipe size significantly, the pumping pressures are close to the maximum bursting pressure of the pipe.
THE CHOICE OF A RATIONAL STRUCTURAL DESIGN OF ELECTRODYNAMIC TRANSPORT SYSTEMS
Directory of Open Access Journals (Sweden)
M. O. Radchenko
2009-03-01
Full Text Available The design schemes of electrodynamic maglev systems with a plane track structure are developed and the results of investigation of levitating motion of such systems along rectilinear or curvilinear tracks are presented.
Applications of the infinite momentum method to quantum electrodynamics and bound state problem
International Nuclear Information System (INIS)
Brodsky, S.J.
1973-01-01
It is shown that the infinite momentum method is a valid and useful calculational alternative to standard perturbation theory methods. The most exciting future applications may be in bound state problems in quantum electrodynamics
Dynamics and stability of a tethered centrifuge in low earth orbit
Quadrelli, B. M.; Lorenzini, E. C.
1992-01-01
The three-dimensional attitude dynamics of a spaceborne tethered centrifuge for artificial gravity experiments in low earth orbit is analyzed using two different methods. First, the tethered centrifuge is modeled as a dumbbell with a straight viscoelastic tether, point tip-masses, and sophisticated environmental models such as nonspherical gravity, thermal perturbations, and a dynamic atmospheric model. The motion of the centrifuge during spin-up, de-spin, and steady-rotation is then simulated. Second, a continuum model of the tether is developed for analyzing the stability of lateral tether oscillations. Results indicate that the maximum fluctuation about the 1-g radial acceleration level is less than 0.001 g; the time required for spin-up and de-spin is less than one orbit; and lateral oscillations are stable for any practical values of the system parameters.
Non-existence of rest-frame spin-eigenstate spinors in their own electrodynamics
Fabbri, Luca; da Rocha, Roldão
2018-05-01
We assume a physical situation where gravity with torsion is neglected for an electrodynamically self-interacting spinor that will be taken in its rest-frame and spin-eigenstate: we demonstrate that under this circumstance no solution exists for the system of field equations. Despite such a situation might look artificial nevertheless it represents the instance that is commonly taken as the basis for all computations of quantum electrodynamics.
Forces and stresses in cryoturbogenerator rotor in presence of short circuit
International Nuclear Information System (INIS)
Kovarskii, M.E.; Rubinraut, A.M.; Tsyrlin, A.L.
1981-01-01
A method is presented for determining the electrodynamic forces, mechanical stresses, and strains in the shells of a cryogenic-turbogenerator cryostat in the presence of an abrupt short circuit. The physical pattern of occurrence of forces in a cryostat shell is considered for capacitive, inductive, and active armature-current cases. It is shown that in addition to the radial component, there is a tangential component of the electrodynamic forces, with the interaction of the two components governing the strength in the presence of short circuits. Results are reported for mechanical-strength calculations, based on the proposed method, for a 200 kw cryogenic turbogenerator
International Nuclear Information System (INIS)
Ritus, V.I.
1987-01-01
This chapter gives methods of formulating the Lagrangian function of an intense field and its asymptotic properties are investigated. Section 2 gives a derivation of the correction pounds to the Lagrangian function resulting from the change in the radiation interaction of the vacuum electrons induced by a constant external field. Section 3 is devoted to the renormalization of the external field as well as the charge and mass of the electron. Like charge renormalization, mass renormalization is performed within the scope of the calculation of the Lagrangian function of the electromagnetic field (without separate consideration of the mass operator or the position of the pole of the Green function of the electron) using a general physical renormalization principle requiring vanishing of the radiation corrections to the observed charge and mass when the field is switched off. This calculation process is performed explicitly in Section 4 where the imaginary part of the Lagrangian function is calculated for weak and strong fields. Here it is noted that the asymptotic behavior of the Lagrangian function with large fields coincides with logarithmic accuracy to the asymptotic behavior of a polarized function with large momenta
Spectral mixture analyses of hyperspectral data acquired using a tethered balloon
Chen, Xuexia; Vierling, Lee
2006-01-01
Tethered balloon remote sensing platforms can be used to study radiometric issues in terrestrial ecosystems by effectively bridging the spatial gap between measurements made on the ground and those acquired via airplane or satellite. In this study, the Short Wave Aerostat-Mounted Imager (SWAMI) tethered balloon-mounted platform was utilized to evaluate linear and nonlinear spectral mixture analysis (SMA) for a grassland-conifer forest ecotone during the summer of 2003. Hyperspectral measurement of a 74-m diameter ground instantaneous field of view (GIFOV) attained by the SWAMI was studied. Hyperspectral spectra of four common endmembers, bare soil, grass, tree, and shadow, were collected in situ, and images captured via video camera were interpreted into accurate areal ground cover fractions for evaluating the mixture models. The comparison between the SWAMI spectrum and the spectrum derived by combining in situ spectral data with video-derived areal fractions indicated that nonlinear effects occurred in the near infrared (NIR) region, while nonlinear influences were minimal in the visible region. The evaluation of hyperspectral and multispectral mixture models indicated that nonlinear mixture model-derived areal fractions were sensitive to the model input data, while the linear mixture model performed more stably. Areal fractions of bare soil were overestimated in all models due to the increased radiance of bare soil resulting from side scattering of NIR radiation by adjacent grass and trees. Unmixing errors occurred mainly due to multiple scattering as well as close endmember spectral correlation. In addition, though an apparent endmember assemblage could be derived using linear approaches to yield low residual error, the tree and shade endmember fractions calculated using this technique were erroneous and therefore separate treatment of endmembers subject to high amounts of multiple scattering (i.e. shadows and trees) must be done with caution. Including the
New theoretical and practical aspects regarding electrodynamic relativity
International Nuclear Information System (INIS)
Manea, Florin; Cazacu, Emil
2005-01-01
The relativity theory of Einstein and Minkowski, based on the principle of inertial systems equivalence and Lorentz's kinematics transformation, was born from the necessity of agreement between the theory of moving mediums and experimental observations. Although Lorentz's transformation was found in pre- relativistic electrodynamics, later the electrodynamics phenomena (and not only) were explained by kinematics relations. Faraday's experiences that rendered manifest importance of the relative movement between the inductor and the induced system, is well known today from the theory and practice of electrical machines. The tensor symbolic intrinsic 'manifest covariant' expressions of the state and evolution equations for the electromagnetic field used by the physicists are elegant but non-intuitive and unfriendly for engineers. The quadritensors of electromagnetic fields contain six independent Cartesian components: two absolute, parallel to the relative translation velocity vector of the inertial reference system and four relative components perpendicular to the velocity vector. That is way it is possible and didactically useful the split of quadritensors and quadrivectors in bitensors and bivectors for simplifying the tensor equations expressed in an explicit matrix form, which is covariant and intuitive. The Lorentz's transformation of space - temporal derivative operators and thus the transformation of proper coordinate of reference system is obtained as a consequence (and not as a premise) of the electromagnetic field properties. For non-relativistic velocities the moving in a magnetic field creates an important electric field but the moving in an electric field leads to an unimportant practically insignificant magnetic field. That is way, the hypothesis that magnetic field density as an absolute value and the constitutive relation B = μ 0 H also the magnetic fields intensity remains absolute, is practically justified. From the Maxwell homogeneous equations a
Effects of energetic electrons on the electrodynamics in the ionosphere
Directory of Open Access Journals (Sweden)
A. Aksnes
2004-01-01
Full Text Available From the observations by the PIXIE and UVI cameras on board the Polar satellite, we derive global maps of the precipitating electron energy spectra from less than 1keV to 100keV. Based on the electron spectra, we generate instantaneous global maps of Hall and Pedersen conductances. The UVI camera provides good coverage of the lower electron energies contributing most to the Pedersen conductance, while PIXIE captures the high energy component of the precipitating electrons affecting the Hall conductance. By characterizing the energetic electrons from some tens of keV and up to about 100keV using PIXIE X-ray measurements, we will, in most cases, calculate a larger electron flux at higher energies than estimated from a simple extrapolation of derived electron spectra from UVI alone. Instantaneous global conductance maps derived with and without inclusion of PIXIE data have been implemented in the Assimilative Mapping of Ionospheric Electrodynamics (AMIE procedure, to study the effects of energetic electrons on electrodynamical parameters in the ionosphere. We find that the improved electron spectral characterization using PIXIE data most often results in a larger Hall conductance and a smaller inferred electric field. In some localized regions the increase in the Hall conductance can exceed 100%. On the contrary, the Pedersen conductance remains more or less unaffected by the inclusion of the PIXIE data. The calculated polar cap potential drop may decrease more than 10%, resulting in a reduction of the estimated Joule heating integrated over the Northern Hemisphere by up to 20%. Locally, Joule heating may decrease more than 50% in some regions. We also find that the calculated energy flux by precipitating electrons increases around 5% when including the PIXIE data. Combined with the reduction of Joule heating, this results in a decrease in the ratio between Joule heating and energy flux, sometimes exceeding 25%. An investigation of the relationship
Implementing phase-covariant cloning in circuit quantum electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Zhu, Meng-Zheng [School of Physics and Material Science, Anhui University, Hefei 230039 (China); School of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Ye, Liu, E-mail: yeliu@ahu.edu.cn [School of Physics and Material Science, Anhui University, Hefei 230039 (China)
2016-10-15
An efficient scheme is proposed to implement phase-covariant quantum cloning by using a superconducting transmon qubit coupled to a microwave cavity resonator in the strong dispersive limit of circuit quantum electrodynamics (QED). By solving the master equation numerically, we plot the Wigner function and Poisson distribution of the cavity mode after each operation in the cloning transformation sequence according to two logic circuits proposed. The visualizations of the quasi-probability distribution in phase-space for the cavity mode and the occupation probability distribution in the Fock basis enable us to penetrate the evolution process of cavity mode during the phase-covariant cloning (PCC) transformation. With the help of numerical simulation method, we find out that the present cloning machine is not the isotropic model because its output fidelity depends on the polar angle and the azimuthal angle of the initial input state on the Bloch sphere. The fidelity for the actual output clone of the present scheme is slightly smaller than one in the theoretical case. The simulation results are consistent with the theoretical ones. This further corroborates our scheme based on circuit QED can implement efficiently PCC transformation.
Ten years of born and infeld electrodynamics investigations
Energy Technology Data Exchange (ETDEWEB)
Vellozo, Sergio O. [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil); Helayel Neto, Jose Abdala [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Assis, Leonardo P. G. De [Stanford University (United States); Gaete, Patricio [U.S.M. (Chile)
2013-07-01
Full text: In this year, our group celebrates ten years of incursions in four-dimensional (3+1) Born and Infeld Electrodynamics (BIE). As is well known, BIE is a classical and nonlinear theory and it predicts a maximum finite value for the electric field, preventing the occurrence of classical singularities. It gives also finite energy for a point-like electric charge. In this period, our main effort was on BIE magnetic sector and the most significant results were: 1. the finite and well behaved magnetostatic field solution for a point-like electric charge at rest, 2. the intrinsic angular momentum (spin) as a self interaction among electric and magnetic field, 3. the cohesive resultant force, using the same natural and simple mechanism, giving stability to the electric charge. Another BIE incursion line stands for three-dimensional (2+1). We investigated the consequences of the space-time dimensionality on the existence of magnetostatic fields generated by electric charges at rest in an inertial frame, which were present in our four-dimensional version. A magnetostatic field associated with an electric charge at rest does not appear in this case. Interestingly, the addition of the topological term (Chern-Simons) to BIE yields the appearance of the magnetostatic field. Finally, we are looking for the hydrogen-like atom spectrum under the BI electrostatic potential, as well the muonic atom spectrum. (author)
Thermodynamics of charged black holes with a nonlinear electrodynamics source
International Nuclear Information System (INIS)
Gonzalez, Hernan A.; Hassaiene, Mokhtar; Martinez, Cristian
2009-01-01
We study the thermodynamical properties of electrically charged black hole solutions of a nonlinear electrodynamics theory defined by a power p of the Maxwell invariant, which is coupled to Einstein gravity in four and higher spacetime dimensions. Depending on the range of the parameter p, these solutions present different asymptotic behaviors. We compute the Euclidean action with the appropriate boundary term in the grand canonical ensemble. The thermodynamical quantities are identified and, in particular, the mass and the charge are shown to be finite for all classes of solutions. Interestingly, a generalized Smarr formula is derived and it is shown that this latter encodes perfectly the different asymptotic behaviors of the black hole solutions. The local stability is analyzed by computing the heat capacity and the electrical permittivity and we find that a set of small black holes is locally stable. In contrast to the standard Reissner-Nordstroem solution, there is a first-order phase transition between a class of these nonlinear charged black holes and the Minkowski spacetime.
Conductivity of higher dimensional holographic superconductors with nonlinear electrodynamics
Sheykhi, Ahmad; Hashemi Asl, Doa; Dehyadegari, Amin
2018-06-01
We investigate analytically as well as numerically the properties of s-wave holographic superconductors in d-dimensional spacetime and in the presence of Logarithmic nonlinear electrodynamics. We study three aspects of this kind of superconductors. First, we obtain, by employing analytical Sturm-Liouville method as well as numerical shooting method, the relation between critical temperature and charge density, ρ, and disclose the effects of both nonlinear parameter b and the dimensions of spacetime, d, on the critical temperature Tc. We find that in each dimension, Tc /ρ 1 / (d - 2) decreases with increasing the nonlinear parameter b while it increases with increasing the dimension of spacetime for a fixed value of b. Then, we calculate the condensation value and critical exponent of the system analytically and numerically and observe that in each dimension, the dimensionless condensation get larger with increasing the nonlinear parameter b. Besides, for a fixed value of b, it increases with increasing the spacetime dimension. We confirm that the results obtained from our analytical method are in agreement with the results obtained from numerical shooting method. This fact further supports the correctness of our analytical method. Finally, we explore the holographic conductivity of this system and find out that the superconducting gap increases with increasing either the nonlinear parameter or the spacetime dimension.
Use of the classical approximation in quantum electrodynamics
International Nuclear Information System (INIS)
Brezin, Edouard
1970-01-01
Approximations commonly used in the study of the classical limit of quantum mechanics are applied, with justification, to quantum electrodynamics. First, the infrared divergence in the scattering of two charged particles is examined with the help of a remarkable series of Feynman diagrams, which in particular preserves gauge invariance and a correct static limit. Looking for the poles in energy of the scattering amplitude, a formula for the binding energies of two charged particles, which generalizes the Balmer formula and takes into account the correct relativistic kinematics, has been derived. A second type of applications concerns phenomena due to the interaction of the electromagnetic field with the vacuum current and charge fluctuations. For instance, when the intensities become very high, the theory predicts the creation of electron-positron pairs by the field. The creation rate is known in the limit of static fields, and the aim of these calculations was to demonstrate the role of frequency in the domain starting from the lowest frequencies up to X-rays. The pair production rate was found to be entirely negligible, even for the most intense laser beams. An increase in frequency, even up to several tens of keV, did not have any effect on the pair production. (author) [fr
A new electrodynamic balance design for low temperature studies
Tong, H.-J.; Ouyang, B.; Pope, F. D.; Kalberer, M.
2014-07-01
In this paper we describe a newly designed cold electrodynamic balance (CEDB) system, which was built to study the evaporation kinetics and freezing properties of supercooled water droplets. The temperature of the CEDB chamber at the location of the levitated water droplet can be controlled in the range: -40 to +40 °C, which is achieved using a combination of liquid nitrogen cooling and heating by positive temperature coefficient heaters. The measurement of liquid droplet radius is obtained by analyzing the Mie elastic light scattering from a 532 nm laser. The Mie scattering signal was also used to characterize and distinguish droplet freezing events; liquid droplets produce a regular fringe pattern whilst the pattern from frozen particles is irregular. The evaporation rate of singly levitated water droplets was calculated from time resolved measurements of the radii of evaporating droplets and a clear trend of the evaporation rate on temperature was measured. The statistical freezing probabilities of aqueous pollen extracts (pollen washing water) are obtained in the temperature range: -4.5 to -40 °C. It was found that that pollen washing water from water birch (Betula fontinalis occidentalis) pollen can act as ice nuclei in the immersion freezing mode at temperatures as warm as -22.45 (±0.65) °C.
Derivation and precision of mean field electrodynamics with mesoscale fluctuations
Zhou, Hongzhe; Blackman, Eric G.
2018-06-01
Mean field electrodynamics (MFE) facilitates practical modelling of secular, large scale properties of astrophysical or laboratory systems with fluctuations. Practitioners commonly assume wide scale separation between mean and fluctuating quantities, to justify equality of ensemble and spatial or temporal averages. Often however, real systems do not exhibit such scale separation. This raises two questions: (I) What are the appropriate generalized equations of MFE in the presence of mesoscale fluctuations? (II) How precise are theoretical predictions from MFE? We address both by first deriving the equations of MFE for different types of averaging, along with mesoscale correction terms that depend on the ratio of averaging scale to variation scale of the mean. We then show that even if these terms are small, predictions of MFE can still have a significant precision error. This error has an intrinsic contribution from the dynamo input parameters and a filtering contribution from differences in the way observations and theory are projected through the measurement kernel. Minimizing the sum of these contributions can produce an optimal scale of averaging that makes the theory maximally precise. The precision error is important to quantify when comparing to observations because it quantifies the resolution of predictive power. We exemplify these principles for galactic dynamos, comment on broader implications, and identify possibilities for further work.
Ultrafast terahertz electrodynamics of photonic and electronic nanostructures
Energy Technology Data Exchange (ETDEWEB)
Luo, Liang [Iowa State Univ., Ames, IA (United States)
2015-01-01
This thesis summarizes my work on using ultrafast laser pulses to study Terahertz (THz) electrodynamics of photonic and electronic nanostructures and microstructures. Ultrafast timeresolved (optical, NIR, MIR, THz) pump-probe spectroscopy setup has been successfully built, which enables me to perform a series of relevant experiments. Firstly, a novel high e ciency and compact THz wave emitter based on split-ring-resonators has been developed and characterized. The emitter can be pumped at any wavelength by tailoring the magnetic resonance and could generate gapless THz waves covering the entire THz band. Secondly, two kinds of new photonic structures for THz wave manipulation have been successfully designed and characterized. One is based on the 1D and 2D photo-imprinted di ractive elements. The other is based on the photoexcited double-split-ring-resonator metamaterials. Both structures are exible and can modulate THz waves with large tunability. Thirdly, the dark excitons in semiconducting singlewalled carbon nanotubes are studied by optical pump and THz probe spectroscopy, which provides the rst insights into the THz responses of nonequilibrium excitonic correlations and dynamics from the dark ground states in carbon nanotubes. Next, several on-going projects are brie y presented such as the study of ultrafast THz dynamics of Dirac fermions in topological insulator Bi_{2}Se_{3} with Mid-infrared excitation. Finally, the thesis ends with a summary of the completed experiments and an outlook of the future plan.
El Naschie's structures in the electrodynamics of polarizable media
International Nuclear Information System (INIS)
Agop, M.; Merches, I.; Enache, V.
2005-01-01
Using the concept of 'combined field', an electrodynamics of polarizable media on a fractal space-time is constructed. In this context, using the scale relativity theory, the permanent electric moment, the induced electric moment, the vacuum fluctuations, the paraelectrics, the diaelectrics, the electric Zeeman-type effect, the electric Einstein-de Haas-type effect, the electric Aharonov-Bohm-type effect, the superconductors in the 'combined field', the double layers as coherent structures, the magnetic Aharonov-Casher-type effect, are analyzed. Correspondence with the ε (∞) space-time is accomplished either by admitting an anomal electric Zeeman-type effect, or through a fractal string as in the case of a superconductor in 'combined field', or, by phase coherence of the electron-ion pairs from the electric double layers (El Naschie's coherence). Moreover, the electric double layer or multiple layer may be considered as two-dimensional projections of the same El Naschie's fractal strings (higher-dimensional strings in ε (∞) space-time)
Scale covariant physics: a 'quantum deformation' of classical electrodynamics
International Nuclear Information System (INIS)
Knoll, Yehonatan; Yavneh, Irad
2010-01-01
We present a deformation of classical electrodynamics, continuously depending on a 'quantum parameter', featuring manifest gauge, Poincare and scale covariance. The theory, dubbed extended charge dynamics (ECD), associates a certain length scale with each charge which, due to scale covariance, is an attribute of a solution, not a parameter of the theory. When the EM field experienced by an ECD charge is slowly varying over that length scale, the dynamics of the charge reduces to classical dynamics, its emitted radiation reduces to the familiar Lienard-Wiechert potential and the above length scale is identified as the charge's Compton length. It is conjectured that quantum mechanics describes statistical aspects of ensembles of ECD solutions, much like classical thermodynamics describes statistical aspects of ensembles of classical solutions. A unique 'remote sensing' feature of ECD, supporting that conjecture, is presented, along with an explanation for the illusion of a photon within a classical treatment of the EM field. Finally, a novel conservation law associated with the scale covariance of ECD is derived, indicating that the scale of a solution may 'drift' with time at a constant rate, much like translation covariance implies a uniform drift of the (average) position.
Circular Orbit Target Capture Using Space Tether-Net System
Directory of Open Access Journals (Sweden)
Guang Zhai
2013-01-01
Full Text Available The space tether-net system for on-orbit capture is proposed in this paper. In order to research the dynamic behaviors during system deployment, both free and nonfree deployment dynamics in circular orbit are developed; the system motion with respect to Local Vertical and Local Horizontal frame is also researched with analysis and simulation. The results show that in the case of free deployment, the capture net follows curve trajectories due to the relative orbit dynamic perturbation, and the initial deployment velocities are planned by state transformation equations for static and floating target captures; in the case of non-free deployment, the system undergoes an altitude libration along the Local Vertical, and the analytical solutions that describe the attitude libration are obtained by using variable separation and integration. Finally, the dynamics of postdeployment system is also proved marginally stable if the critical initial conditions are satisfied.
Kv7 channels can function without constitutive calmodulin tethering.
Directory of Open Access Journals (Sweden)
Juan Camilo Gómez-Posada
Full Text Available M-channels are voltage-gated potassium channels composed of Kv7.2-7.5 subunits that serve as important regulators of neuronal excitability. Calmodulin binding is required for Kv7 channel function and mutations in Kv7.2 that disrupt calmodulin binding cause Benign Familial Neonatal Convulsions (BFNC, a dominantly inherited human epilepsy. On the basis that Kv7.2 mutants deficient in calmodulin binding are not functional, calmodulin has been defined as an auxiliary subunit of Kv7 channels. However, we have identified a presumably phosphomimetic mutation S511D that permits calmodulin-independent function. Thus, our data reveal that constitutive tethering of calmodulin is not required for Kv7 channel function.
DOE Geothermal Data Repository - Tethering Data to Information: Preprint
Energy Technology Data Exchange (ETDEWEB)
Weers, J.; Anderson, A.
2014-02-01
Data are not inherently information. Without context, data are just numbers, figures, names, or points on a line. By assigning context to data, we can validate ideas, form opinions, and generate knowledge. This is an important distinction to information scientists, as we recognize that the context in which we keep our data plays a big part in generating its value. The mechanisms used to assign this context often include their own data, supplemental to the data being described and defining semantic relationships, commonly referred to as metadata. This paper provides the status of the DOE Geothermal Data Repository (DOE GDR), including recent efforts to tether data submissions to information, discusses the important distinction between data and information, outlines a path to generate useful knowledge from raw data, and details the steps taken in order to become a node on the National Geothermal Data System (NGDS).
Tethered and Polymer Supported Bilayer Lipid Membranes: Structure and Function
Directory of Open Access Journals (Sweden)
Jakob Andersson
2016-05-01
Full Text Available Solid supported bilayer lipid membranes are model systems to mimic natural cell membranes in order to understand structural and functional properties of such systems. The use of a model system allows for the use of a wide variety of analytical tools including atomic force microscopy, impedance spectroscopy, neutron reflectometry, and surface plasmon resonance spectroscopy. Among the large number of different types of model membranes polymer-supported and tethered lipid bilayers have been shown to be versatile and useful systems. Both systems consist of a lipid bilayer, which is de-coupled from an underlying support by a spacer cushion. Both systems will be reviewed, with an emphasis on the effect that the spacer moiety has on the bilayer properties.
Physisorbed Polymer-Tethered Lipid Bilayer with Lipopolymer Gradient
Directory of Open Access Journals (Sweden)
Christoph A. Naumann
2012-11-01
Full Text Available Physisorbed polymer-tethered lipid bilayers consisting of phospholipids and lipopolymers represent an attractive planar model membrane platform, in which bilayer fluidity and membrane elastic properties can be regulated through lipopolymer molar concentration. Herein we report a method for the fabrication of such a planar model membrane system with a lateral gradient of lipopolymer density. In addition, a procedure is described, which leads to a sharp boundary between regions of low and high lipopolymer molar concentrations. Resulting gradients and sharp boundaries are visualized on the basis of membrane buckling structures at elevated lipopolymer concentrations using epifluorescence microscopy and atomic force microscopy. Furthermore, results from spot photobleaching experiments are presented, which provide insight into the lipid lateral fluidity in these model membrane architectures. The presented experimental data highlight a planar, solid-supported membrane characterized by fascinating length scale-dependent dynamics and elastic properties with remarkable parallels to those observed in cellular membranes.
Heterobifunctional crosslinkers for tethering single ligand molecules to scanning probes
International Nuclear Information System (INIS)
Riener, Christian K.; Kienberger, Ferry; Hahn, Christoph D.; Buchinger, Gerhard M.; Egwim, Innocent O.C.; Haselgruebler, Thomas; Ebner, Andreas; Romanin, Christoph; Klampfl, Christian; Lackner, Bernd; Prinz, Heino; Blaas, Dieter; Hinterdorfer, Peter; Gruber, Hermann J.
2003-01-01
Single molecule recognition force microscopy (SMRFM) is a versatile atomic force microscopy (AFM) method to probe specific interactions of cognitive molecules on the single molecule level. It allows insights to be gained into interaction potentials and kinetic barriers and is capable of mapping interaction sites with nm positional accuracy. These applications require a ligand to be attached to the AFM tip, preferably by a distensible poly(ethylene glycol) (PEG) chain between the measuring tip and the ligand molecule. The PEG chain greatly facilitates specific binding of the ligand to immobile receptor sites on the sample surface. The present study contributes to tip-PEG-ligand tethering in three ways: (i) a convenient synthetic route was found to prepare NH 2 -PEG-COOH which is the key intermediate for long heterobifunctional crosslinkers; (ii) a variety of heterobifunctional PEG derivatives for tip-PEG-ligand linking were prepared from NH 2 -PEG-COOH; (iii) in particular, a new PEG crosslinker with one thiol-reactive end and one terminal nitrilotriacetic acid (NTA) group was synthesized and successfully used to tether His 6 -tagged protein molecules to AFM tips via noncovalent NTA-Ni 2+ -His 6 bridges. The new crosslinker was applied to link a recombinant His 6 -tagged fragment of the very-low density lipoprotein receptor to the AFM tip whereupon specific docking to the capsid of human rhinovirus particles was observed by force microscopy. In a parallel study, the specific interaction of the small GTPase Ran with the nuclear import receptor importin β1 was studied in detail by SMRFM, using the new crosslinker to link His 6 -tagged Ran to the measuring tip [Nat. Struct. Biol. (2003), 10, 553-557
Elasticity of Hard-Spheres-And-Tether Systems
International Nuclear Information System (INIS)
Farago, O.; Kantor, Y.
1999-01-01
Physical properties of a large class of systems ranging from noble gases to polymers and rubber are primarily determined by entropy, while the internal energy plays a minor role. Such systems can be conveniently modeled and numerically studied using ''hard' (i.e., ''infinity-or-zero'') potentials, such as hard sphere repulsive interactions, or inextensible (''tether'') bonds which limit the distance between the bonded monomers, but have zero energy at all permitted distances. The knowledge of elastic constants is very important for understanding the behavior of entropy-dominated systems. Computational methods for determination of the elastic constants in such systems are broadly classified into ''strain'' methods and (fluctuation methods. In the former, the elastic constants are extracted from stress-strain relations, while in the latter they are determined from measurements of stress fluctuations. The fluctuation technique usually enables more accurate and well-controlled determination of the elastic constants since in this method the elastic constants are computed directly from simulations of the un strained system with no need to deform the simulation cell and perform numerical differentiations. For central forces systems, the original ''fluctuation'' formalism can be applied provided the pair potential is twice differentiable. We have extended this formalism to apply to hard-spheres-and-tether models in which this requirement is not fulfilled. We found that for such models the components of the tensor of elastic constants can be related to (two-, three- and four-point) probability densities of contacts between hard spheres and stretched bonds. We have tested our formalism on simple (phantom networks and three-dimensional hard spheres systems
Minimally invasive tethered cord release in children: A technical note
Directory of Open Access Journals (Sweden)
S. Kağan Başarslan
2014-03-01
Full Text Available Tethered cord release is commonly performed in pediatric neurosurgery. Nowadays, minimally invasive procedures are created growing interest due to its highly tolerable nature for surgery. It has been main purpose a minimal damaging on access route and maximum protection of normal structures in surgery. We present a surgical treatment of tethered cord syndrome, by which is provided the cord releasing unlike the many methods being applied with tissue removal. The main advantage of performing this surgery through 2 cm hole is to avoid removing ligamentum flavum and bony structure like lamina in addition to reduce the length of the incision and the related scar tissue. J Clin Exp Invest 2014; 5 (1: 115-117 Technical note: the patient was taken on the operating table in the sitting-prone position, and L5-S1 distance was determined by fluoroscopy. The skin and subcutaneous tissues was passed via a 2 cm vertical incision settled in 0.5 cm laterally from midline. L5-S1 distance and its covering ligamentum flavum are displayed by the guidance of L5 lamina. Williams’s retractor was placed in the distance after fetching microscope. The foregoing procedures are the same with microdiscectomic surgery. By a vertical incision made on the flavum, its both layer was lifted up and hanged with simple suture on the back tissue for a comfortable exposure of the Dura. Thecal sac was opened by 0.5 cm long vertical incision on the Dura after obtaining secure CSF drainage with the help of yellow-tipped syringe needle. With finding by a nerve hook, the phylum was burned and released securely. Then the Dura was sutured primarily for the closure by means of microsurgery instruments, and flavum was laid on it again.
Experiments and simulation of a net closing mechanism for tether-net capture of space debris
Sharf, Inna; Thomsen, Benjamin; Botta, Eleonora M.; Misra, Arun K.
2017-10-01
This research addresses the design and testing of a debris containment system for use in a tether-net approach to space debris removal. The tether-net active debris removal involves the ejection of a net from a spacecraft by applying impulses to masses on the net, subsequent expansion of the net, the envelopment and capture of the debris target, and the de-orbiting of the debris via a tether to the chaser spacecraft. To ensure a debris removal mission's success, it is important that the debris be successfully captured and then, secured within the net. To this end, we present a concept for a net closing mechanism, which we believe will permit consistently successful debris capture via a simple and unobtrusive design. This net closing system functions by extending the main tether connecting the chaser spacecraft and the net vertex to the perimeter and around the perimeter of the net, allowing the tether to actuate closure of the net in a manner similar to a cinch cord. A particular embodiment of the design in a laboratory test-bed is described: the test-bed itself is comprised of a scaled-down tether-net, a supporting frame and a mock-up debris. Experiments conducted with the facility demonstrate the practicality of the net closing system. A model of the net closure concept has been integrated into the previously developed dynamics simulator of the chaser/tether-net/debris system. Simulations under tether tensioning conditions demonstrate the effectiveness of the closure concept for debris containment, in the gravity-free environment of space, for a realistic debris target. The on-ground experimental test-bed is also used to showcase its utility for validating the dynamics simulation of the net deployment, and a full-scale automated setup would make possible a range of validation studies of other aspects of a tether-net debris capture mission.
Xia, Guangqing; Han, Yajie; Chen, Liuwei; Wei, Yanming; Yu, Yang; Chen, Maolin
2018-06-01
The interaction between the solar wind plasma and the bias voltage of long tethers is the basic mechanism of the electric sail thruster. The momentum transfer process between the solar wind plasma and electric tethers was investigated using a 2D full particle PIC method. The coupled electric field distribution and deflected ion trajectory under different bias voltages were compared, and the influence of bias voltage on momentum transfer process was analyzed. The results show that the high potential of the bias voltage of long tethers will slow down, stagnate, reflect and deflect a large number of ions, so that ion cavities are formed in the vicinity of the tether, and the ions will transmit the axial momentum to the sail tethers to produce the thrust. Compared to the singe tether, double tethers show a better thrust performance.
Williamson, P. R.; Banks, P. M.
1976-01-01
The objectives of the Tethered Balloon Current Generator experiment are to: (1) generate relatively large regions of thermalized, field-aligned currents, (2) produce controlled-amplitude Alfven waves, (3) study current-driven electrostatic plasma instabilities, and (4) generate substantial amounts of power or propulsion through the MHD interaction. A large balloon (a diameter of about 30 m) will be deployed with a conducting surface above the space shuttle at a distance of about 10 km. For a generally eastward directed orbit at an altitude near 400 km, the balloon, connected to the shuttle by a conducting wire, will be positive with respect to the shuttle, enabling it to collect electrons. At the same time, the shuttle will collect positive ions and, upon command, emit an electron beam to vary current flow in the system.
Schubert, Wayne H.; Ciesielski, Paul E.; Guinn, Thomas A.; Cox, Stephen K.; Mckee, Thomas B.
1990-01-01
During the FIRE Marine Stratocumulus Program on San Nicolas Island, Colorado State University (CSU) and the British Meteorological Office (BMO) operated separate instrument packages on the NASA tethered balloon. The CSU package contained instrumentation for the measurement of temperature, pressure, humidity, cloud droplet concentration, and long and short wave radiation. Eight research flights, performed between July 7 and July 14, are summarized. An analysis priority to the July 7, 8 and 11 flights was assigned for the purposes of comparing the CSU and BMO data. Results are presented. In addition, CSU operated a laser ceilometer for the determination of cloud base, and a CLASS radiosonde site which launched 69 sondes. Data from all of the above systems are being analyzed.
Macroscopic quantum electrodynamics of high-Q cavities
Energy Technology Data Exchange (ETDEWEB)
Khanbekyan, Mikayel
2009-10-27
In this thesis macroscopic quantum electrodynamics in linear media was applied in order to develop an universally valid quantum theory for the description of the interaction of the electromagnetic field with atomic sources in high-Q cavities. In this theory a complete description of the characteristics of the emitted radiation is given. The theory allows to show the limits of the applicability of the usually applied theory. In order to establish an as possible generally valid theory first the atom-field interaction was studied in the framework of macroscopic quantum electrodynamics in dispersive and absorptive media. In order to describe the electromagnetic field from Maxwell's equations was started, whereby the noise-current densities, which are connected with the absorption of the medium, were included. The solution of these equations expresses the electromagnetic field variables by the noise-current densities by means of Green's tensor of the macroscopic Maxwell equations. The explicit quantization is performed by means of the noise-current densities, whereby a diagonal Hamiltonian is introduced, which then guarantees the time development according to Maxwell's equation and the fulfillment of the fundamental simultaneous commutation relations of the field variables. In the case of the interaction of the medium-supported field with atoms the Hamiltonian must be extended by atom-field interactions energies, whereby the canonical coupling schemes of the minimal or multipolar coupling can be used. The dieelectric properties of the material bodies as well as their shape are coded in the Green tensor of the macroscopic Maxwell equations. As preparing step first the Green tensor was specified in order to derive three-dimensional input-output relations for the electromagnetic field operators on a plane multilayer structure. Such a general dewscription of the electromagnetic field allows the inclusion both of dispersion and absorption of the media and the
Quantum-electrodynamic influences on the lifetime of metastable states
International Nuclear Information System (INIS)
Brenner, G.
2007-01-01
High-precision lifetime measurements of the metastable 1s 2 2s 2 2p 2 P 0 3/2 level in boronlike Ar XIV and the 3s 2 2p 2 P 0 3/2 level in aluminumlike Fe XIV were performed at the Heidelberg electron beam ion trap (HD-EBIT). The lifetimes were inferred by monitoring their optical decay curves resulting from the magnetic dipole (M1) transition 1s 2 2s 2 2p 2 P 0 3/2 - 2 P 0 1/2 and 3s 2 3p 2 P 0 3/2 - 2 P 0 1/2 to the ground state configuration with transition wavelengths of 441.256 nm and 530.29 nm, respectively. Possible systematic error sources were investigated by studying the dependence of the decay times of the curves on various trapping conditions with high statistical significance. A new trapping scheme for lifetime measurements at an EBIT has been applied and allowed to reach an unprecedented precision in the realm of lifetime determinations on highly charged ions. The results of 9.573(4)( +12 -5 ) ms (stat)(syst) for Ar XIV and 16.726(10)(+17) ms (stat)(syst) for Fe XIV with a relative accuracy of 0.14% and 0.13%, respectively, make these measurements for the first time sensitive to quantum electrodynamic effects like the electron anomalous magnetic moment (EAMM). The results, improving the accuracy of previous measurements by factors of 10 and 6, respectively, show a clear discrepancy of about 3σ and 4σ to the trend of existing theoretical models, which in almost all cases predict a shorter lifetime, when adjusted for the EAMM. The obvious disagreement between experimental results and the predictions points at the incompleteness of the theoretical models used. (orig.)
Random electrodynamics : a classical foundation for key quantum concepts
International Nuclear Information System (INIS)
Sachidanandam, S.
1981-01-01
The model of random electrodynamics, in which electromagnetic particles are subjected, in a classical manner, to the forces of radiation damping and the fluctuating zero-point fields provides the framework in which the following results are obtained: (1) The precession dynamics of a long-lived, non-relativistic particle with a magnetic moment proportional to its spin, leads to a self-consistent determination of the spin value as one-half. (2) The internal dynamic underlying the intrinsic magnetic moment of a Dirac particle yields a classically visualizable picture of the spin-magnetic moment. (3) The Bose correlation among indistinguishable, non-interacting, spin-zero Particles arises from the coupling through the common- zero point fields and the radiation reaction fields when the particles are close together in both the r vector and the energy spaces. (4) The (exclusion principle-induced) correlation among identical, non-interacting magnetic particles with spin 1/2 is brought about by the coupling, (through the common fields of radiation reaction and the vacuum fluctuations), of the spins as well as the translational motions when the particles are close together in r vector and the energy spaces. (5) A dilute gas of free electrons has a Maxwellian distribution of velocities and the correct value of the djamagnetic moment in the presence of a magnetic field. Considerations on the centre of mass motion of a composite neutral particle lead to a simple resolution of the foundational paradoxes of statistical mechanics. (6) An approximate treatment of the hydrogen atom leads to a description of the evolution to the ground state at absolute zero and an estimation of the mass frequency and the line-width of the radiation emitted when an excited atom decays. (author)
Higher order energy transfer. Quantum electrodynamical calculations and graphical representation
International Nuclear Information System (INIS)
Jenkins, R.D.
2000-01-01
In Chapter 1, a novel method of calculating quantum electrodynamic amplitudes is formulated using combinatorial theory. This technique is used throughout instead of conventional time-ordered methods. A variety of hyperspaces are discussed to highlight isomorphism between a number of A generalisation of Pascal's triangle is shown to be beneficial in determining the form of hyperspace graphs. Chapter 2 describes laser assisted resonance energy transfer (LARET), a higher order perturbative contribution to the well-known process resonance energy transfer, accommodating an off resonance auxiliary laser field to stimulate the migration. Interest focuses on energy exchanges between two uncorrelated molecular species, as in a system where molecules are randomly oriented. Both phase-weighted and standard isotropic averaging are required for the calculations. Results are discussed in terms of a laser intensity-dependent mechanism. Identifying the applied field regime where LARET should prove experimentally significant, transfer rate increases of up to 30% are predicted. General results for three-center energy transfer are elucidated in chapter 3. Cooperative and accretive mechanistic pathways are identified with theory formulated to elicit their role in a variety of energy transfer phenomena and their relative dominance. In multichromophoric the interplay of such factors is analysed with regard to molecular architectures. The alignments and magnitudes of donor and acceptor transition moments and polarisabilities prove to have profound effects on achievable pooling efficiency for linear configurations. Also optimum configurations are offered. In ionic lattices, although both mechanisms play significant roles in pooling and cutting processes, only the accretive is responsible for sensitisation. The local, microscopic level results are used to gauge the lattice response, encompassing concentration and structural effects. (author)
Development of a Tethered Formation Flight Testbed for ISS, Phase I
National Aeronautics and Space Administration — The development of a testbed for the development and demonstration of technologies needed by tethered formation flying satellites is proposed. Such a testbed would...
Significance of relative velocity in drag force or drag power estimation for a tethered float
Digital Repository Service at National Institute of Oceanography (India)
Vethamony, P.; Sastry, J.S.
There is difference in opinion regarding the use of relative velocity instead of particle velocity alone in the estimation of drag force or power. In the present study, a tethered spherical float which undergoes oscillatory motion in regular waves...
Vesicle fusion observed by content transfer across a tethered lipid bilayer.
Rawle, Robert J; van Lengerich, Bettina; Chung, Minsub; Bendix, Poul Martin; Boxer, Steven G
2011-10-19
Synaptic transmission is achieved by exocytosis of small, synaptic vesicles containing neurotransmitters across the plasma membrane. Here, we use a DNA-tethered freestanding bilayer as a target architecture that allows observation of content transfer of individual vesicles across the tethered planar bilayer. Tethering and fusion are mediated by hybridization of complementary DNA-lipid conjugates inserted into the two membranes, and content transfer is monitored by the dequenching of an aqueous content dye. By analyzing the diffusion profile of the aqueous dye after vesicle fusion, we are able to distinguish content transfer across the tethered bilayer patch from vesicle leakage above the patch. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.
The motion and control of a complex three-body space tethered system
Shi, Gefei; Zhu, Zhanxia; Chen, Shiyu; Yuan, Jianping; Tang, Biwei
2017-11-01
This paper is mainly devoted to investigating the dynamics and stability control of a three body-tethered satellite system which contains a main satellite and two subsatellites connected by two straight, massless and inextensible tethers. Firstly, a detailed mathematical model is established in the central gravitational field. Then, the dynamic characteristics of the established system are investigated and analyzed. Based on the dynamic analysis, a novel sliding mode prediction model (SMPM) control strategy is proposed to suppress the motion of the built tethered system. The numerical results show that the proposed underactuated control law is highly effective in suppressing the attitude/libration motion of the underactuated three-body tethered system. Furthermore, cases of different target angles are also examined and analyzed. The simulation results reveal that even if the final equilibrium states differ from different selections of the target angles, the whole system can still be maintained in acceptable areas.
An Effective Approach Control Scheme for the Tethered Space Robot System
Directory of Open Access Journals (Sweden)
Zhongjie Meng
2014-09-01
Full Text Available The tethered space robot system (TSR, which is composed of a platform, a gripper and a space tether, has great potential in future space missions. Given the relative motion among the platform, tether, gripper and the target, an integrated approach model is derived. Then, a novel coordinated approach control scheme is presented, in which the tether tension, thrusters and the reaction wheel are all utilized. It contains the open-loop trajectory optimization, the feedback trajectory control and attitude control. The numerical simulation results show that the rendezvous between TSR and the target can be realized by the proposed coordinated control scheme, and the propellant consumption is efficiently reduced. Moreover, the control scheme performs well in the presence of the initial state's perturbations, actuator characteristics and sensor errors.
Myocardial Infarction Alters Adaptation of the Tethered Mitral Valve
Dal-Bianco, Jacob P; Aikawa, Elena; Bischoff, Joyce; Guerrero, J Luis; Hjortnaes, Jesper; Beaudoin, Jonathan; Szymanski, Catherine; Bartko, Philipp E; Seybolt, Margo M; Handschumacher, Mark D; Sullivan, Suzanne; Garcia, Michael L; Mauskapf, Adam; Titus, James S; Wylie-Sears, Jill; Irvin, Whitney S; Chaput, Miguel; Messas, Emmanuel; Hagège, Albert A; Carpentier, Alain; Levine, Robert A
2016-01-01
BACKGROUND: In patients with myocardial infarction (MI), leaflet tethering by displaced papillary muscles induces mitral regurgitation (MR), which doubles mortality. Mitral valves (MVs) are larger in such patients but fibrosis sets in counterproductively. The investigators previously reported that
Todoroki, Chiaki; Takahashi, Yasutake; Nakamura, Takayuki
2015-01-01
This paper shows human skill acquisition systems to control the kite-based tethered flying robot. The kite-based tethered flying robot has been proposed as a flying observation system with long-term activity capability[1]. It is a relatively new system and aimed to complement other information gathering systems using a balloon or an air vehicle. This paper shows some approaches of human operation characteristics acquisition based on fuzzy learning controller, knearest neighbor algorithm, and ...
Directory of Open Access Journals (Sweden)
Keiichiro Hara
2007-03-01
Full Text Available The 46th Japanese Antarctic Research Expedition (JARE-46 carried out twenty seven tethered-balloon-borne aerosol measurements at Syowa Station for better understanding of aerosol chemical and physical properties in the lower troposphere from 6th January 2005 until 11 December 2005. This report summarizes the plan, preparation, field activities and some troubles/problems in the tethered-balloon observations.
Four-dimensional black holes with scalar hair in nonlinear electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Barrientos, Jose [Universidad de Concepcion, Departamento de Fisica, Concepcion (Chile); Universidad Catolica del Norte, Departamento de Ensenanza de las Ciencias Basicas, Coquimbo (Chile); Gonzalez, P.A. [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile); Vasquez, Yerko [Universidad de La Serena, Departamento de Fisica y Astronomia, Facultad de Ciencias, La Serena (Chile)
2016-12-15
We consider a gravitating system consisting of a scalar field minimally coupled to gravity with a self-interacting potential and a U(1) nonlinear electromagnetic field. Solving analytically and numerically the coupled system for both power-law and Born-Infeld type electrodynamics, we find charged hairy black hole solutions. Then we study the thermodynamics of these solutions and we find that at a low temperature the topological charged black hole with scalar hair is thermodynamically preferred, whereas the topological charged black hole without scalar hair is thermodynamically preferred at a high temperature for power-law electrodynamics. Interestingly enough, these phase transitions occur at a fixed critical temperature and do not depend on the exponent p of the nonlinear electrodynamics. (orig.)
Four-dimensional black holes with scalar hair in nonlinear electrodynamics
International Nuclear Information System (INIS)
Barrientos, Jose; Gonzalez, P.A.; Vasquez, Yerko
2016-01-01
We consider a gravitating system consisting of a scalar field minimally coupled to gravity with a self-interacting potential and a U(1) nonlinear electromagnetic field. Solving analytically and numerically the coupled system for both power-law and Born-Infeld type electrodynamics, we find charged hairy black hole solutions. Then we study the thermodynamics of these solutions and we find that at a low temperature the topological charged black hole with scalar hair is thermodynamically preferred, whereas the topological charged black hole without scalar hair is thermodynamically preferred at a high temperature for power-law electrodynamics. Interestingly enough, these phase transitions occur at a fixed critical temperature and do not depend on the exponent p of the nonlinear electrodynamics. (orig.)
Biomimicry enhances sequential reactions of tethered glycolytic enzymes, TPI and GAPDHS.
Directory of Open Access Journals (Sweden)
Chinatsu Mukai
Full Text Available Maintaining activity of enzymes tethered to solid interfaces remains a major challenge in developing hybrid organic-inorganic devices. In nature, mammalian spermatozoa have overcome this design challenge by having glycolytic enzymes with specialized targeting domains that enable them to function while tethered to a cytoskeletal element. As a step toward designing a hybrid organic-inorganic ATP-generating system, we implemented a biomimetic site-specific immobilization strategy to tether two glycolytic enzymes representing different functional enzyme families: triose phosphoisomerase (TPI; an isomerase and glyceraldehyde 3-phosphate dehydrogenase (GAPDHS; an oxidoreductase. We then evaluated the activities of these enzymes in comparison to when they were tethered via classical carboxyl-amine crosslinking. Both enzymes show similar surface binding regardless of immobilization method. Remarkably, specific activities for both enzymes were significantly higher when tethered using the biomimetic, site-specific immobilization approach. Using this biomimetic approach, we tethered both enzymes to a single surface and demonstrated their function in series in both forward and reverse directions. Again, the activities in series were significantly higher in both directions when the enzymes were coupled using this biomimetic approach versus carboxyl-amine binding. Our results suggest that biomimetic, site-specific immobilization can provide important functional advantages over chemically specific, but non-oriented attachment, an important strategic insight given the growing interest in recapitulating entire biological pathways on hybrid organic-inorganic devices.
Biomimicry enhances sequential reactions of tethered glycolytic enzymes, TPI and GAPDHS.
Mukai, Chinatsu; Gao, Lizeng; Bergkvist, Magnus; Nelson, Jacquelyn L; Hinchman, Meleana M; Travis, Alexander J
2013-01-01
Maintaining activity of enzymes tethered to solid interfaces remains a major challenge in developing hybrid organic-inorganic devices. In nature, mammalian spermatozoa have overcome this design challenge by having glycolytic enzymes with specialized targeting domains that enable them to function while tethered to a cytoskeletal element. As a step toward designing a hybrid organic-inorganic ATP-generating system, we implemented a biomimetic site-specific immobilization strategy to tether two glycolytic enzymes representing different functional enzyme families: triose phosphoisomerase (TPI; an isomerase) and glyceraldehyde 3-phosphate dehydrogenase (GAPDHS; an oxidoreductase). We then evaluated the activities of these enzymes in comparison to when they were tethered via classical carboxyl-amine crosslinking. Both enzymes show similar surface binding regardless of immobilization method. Remarkably, specific activities for both enzymes were significantly higher when tethered using the biomimetic, site-specific immobilization approach. Using this biomimetic approach, we tethered both enzymes to a single surface and demonstrated their function in series in both forward and reverse directions. Again, the activities in series were significantly higher in both directions when the enzymes were coupled using this biomimetic approach versus carboxyl-amine binding. Our results suggest that biomimetic, site-specific immobilization can provide important functional advantages over chemically specific, but non-oriented attachment, an important strategic insight given the growing interest in recapitulating entire biological pathways on hybrid organic-inorganic devices.
The mechanics of motorised momentum exchange tethers when applied to active debris removal from LEO
Energy Technology Data Exchange (ETDEWEB)
Caldecott, Ralph; Kamarulzaman, Dayangku N. S.; Kirrane, James P.; Cartmell, Matthew P.; Ganilova, Olga A. [Department of Mechanical Engineering, University of Sheffield, Mappin St., Sheffield, S1 3JD, England (United Kingdom)
2014-12-10
The concept of momentum exchange when applied to space tethers for propulsion is well established, and a considerable body of literature now exists on the on-orbit modelling, the dynamics, and also the control of a large range of tether system applications. The authors consider here a new application for the Motorised Momentum Exchange Tether by highlighting three key stages of development leading to a conceptualisation that can subsequently be developed into a technology for Active Debris Removal. The paper starts with a study of the on-orbit mechanics of a full sized motorised tether in which it is shown that a laden and therefore highly massasymmetrical tether can still be forced to spin, and certainly to librate, thereby confirming its possible usefulness for active debris removal (ADR). The second part of the paper concentrates on the modelling of the centripetal deployment of a symmetrical MMET in order to get it initialized for debris removal operations, and the third and final part of the paper provides an entry into scale modelling for low cost mission design and testing. It is shown that the motorised momentum exchange tether offers a potential solution to the removal of large pieces of orbital debris, and that dynamic methodologies can be implemented to in order to optimise the emergent design.
The mechanics of motorised momentum exchange tethers when applied to active debris removal from LEO
International Nuclear Information System (INIS)
Caldecott, Ralph; Kamarulzaman, Dayangku N. S.; Kirrane, James P.; Cartmell, Matthew P.; Ganilova, Olga A.
2014-01-01
The concept of momentum exchange when applied to space tethers for propulsion is well established, and a considerable body of literature now exists on the on-orbit modelling, the dynamics, and also the control of a large range of tether system applications. The authors consider here a new application for the Motorised Momentum Exchange Tether by highlighting three key stages of development leading to a conceptualisation that can subsequently be developed into a technology for Active Debris Removal. The paper starts with a study of the on-orbit mechanics of a full sized motorised tether in which it is shown that a laden and therefore highly massasymmetrical tether can still be forced to spin, and certainly to librate, thereby confirming its possible usefulness for active debris removal (ADR). The second part of the paper concentrates on the modelling of the centripetal deployment of a symmetrical MMET in order to get it initialized for debris removal operations, and the third and final part of the paper provides an entry into scale modelling for low cost mission design and testing. It is shown that the motorised momentum exchange tether offers a potential solution to the removal of large pieces of orbital debris, and that dynamic methodologies can be implemented to in order to optimise the emergent design
Yizengaw, E.; Moldwin, M.; Zesta, E.
2015-12-01
The currently funded African Meridian B-Field Education and Research (AMBER) magnetometer array comprises more than thirteen magnetometers stationed globally in the vicinity of geomagnetic equator. One of the main objectives of AMBER network is to understand the longitudinal variability of equatorial electrodynamics as function of local time, magnetic activity, and season. While providing complete meridian observation in the region and filling the largest land-based gap in global magnetometer coverage, the AMBER array addresses two fundamental areas of space physics: first, the processes governing electrodynamics of the equatorial ionosphere as a function of latitude (or L-shell), local time, longitude, magnetic activity, and season, and second, ULF pulsation strength at low/mid-latitude regions and its connection with equatorial electrojet and density fluctuation. The global AMBER network can also be used to augment observations from space-based instruments, such us the triplet SWARM mission and the upcoming ICON missions. Thus, in coordination with space-based and other ground-based observations, the AMBER magnetometer network provides a great opportunity to understand the electrodynamics that governs equatorial ionosphere motions. In this paper we present the longitudinal variability of the equatorial electrodynamics using the combination of instruments onboard SWARM and C/NOFS satellites and ground-based AMBER network. Both ground- and pace-based observations show stronger dayside and evening sector equatorial electrodynamics in the American and Asian sectors compared to the African sector. On the other hand, the African sector is home to stronger and year-round ionospheric bubbles/irregularities compared to the American and Asian sectors. This raises the question if the evening sector equatorial electrodynamics (vertical drift), which is believed to be the main cause for the enhancement of Rayleigh-Taylor (RT) instability growth rate, is stronger in the
Run-away electrons in relativistic spin (1) /(2) quantum electrodynamics
International Nuclear Information System (INIS)
Low, F.E.
1998-01-01
The existence of run-away solutions in classical and non-relativistic quantum electrodynamics is reviewed. It is shown that the less singular high energy behavior of relativistic spin (1) /(2) quantum electrodynamics precludes an analogous behavior in that theory. However, a Landau-like anomalous pole in the photon propagation function or in the electron-massive photon forward scattering amplitude would generate a new run-away, characterized by an energy scale ω∼m e thinspexp(1/α). This contrasts with the energy scale ω∼m e /α associated with the classical and non-relativistic quantum run-aways. copyright 1998 Academic Press, Inc
(2+1-dimensional regular black holes with nonlinear electrodynamics sources
Directory of Open Access Journals (Sweden)
Yun He
2017-11-01
Full Text Available On the basis of two requirements: the avoidance of the curvature singularity and the Maxwell theory as the weak field limit of the nonlinear electrodynamics, we find two restricted conditions on the metric function of (2+1-dimensional regular black hole in general relativity coupled with nonlinear electrodynamics sources. By the use of the two conditions, we obtain a general approach to construct (2+1-dimensional regular black holes. In this manner, we construct four (2+1-dimensional regular black holes as examples. We also study the thermodynamic properties of the regular black holes and verify the first law of black hole thermodynamics.
Flow structures around a beetle in a tethered flight
Lee, Boogeon; Oh, Sehyeong; Park, Hyungmin; Choi, Haecheon
2017-11-01
In the present study, through a wind-tunnel experiment, we visualize the flow in a tethered flight of a rhinoceros beetle using a smoke-wire visualization technique. Measurements are done at five side planes along the wind span while varying the body angle (angle between the horizontal and the body axis) to investigate the influence of the stroke plane angle that was observed to change depending on the flight mode such as hovering, forward and takeoff flights so on. Observing that a large attached leading-edge vortex is only found on the hindwing, it is inferred that most of the aerodynamic forces would be generated by hindwings (flexible inner wings) compared to the elytra (hard outer wings). In addition, it is observed to use unsteady lift-generating mechanisms such as clap-and-fling, wing-wing interaction and wake capture. Finally, we discuss the relation between the advance ratio and Strouhal number by adjusting free-stream velocity and the body angle (i.e., angle of wake-induced flow). Supported by a Grant to Bio-Mimetic Robot Research Center Funded by Defense Acquisition Program Administration, and by ADD, Korea (UD130070ID).
Lipoproteins tethered dendrimeric nanoconstructs for effective targeting to cancer cells
Jain, Anupriya; Jain, Keerti; Mehra, Neelesh Kumar; Jain, N. K.
2013-10-01
In the present investigation, poly (propylene imine) dendrimers up to fifth generation (PPI G5.0) were synthesized using ethylene diamine and acrylonitrile. Lipoproteins (high-density lipoprotein; HDL and low-density lipoprotein; LDL) were isolated from human plasma by discontinuous density gradient ultracentrifugation, characterized and tethered to G5.0 PPI dendrimers to construct LDL- and HDL-conjugated dendrimeric nanoconstructs for tumor-specific delivery of docetaxel. Developed formulations showed sustained release characteristics in in vitro drug release and in vivo pharmacokinetic studies. The cancer targeting potential of lipoprotein coupled dendrimers was investigated by ex vivo cytotoxicity and cell uptake studies using human hepatocellular carcinoma cell lines (HepG2 cells) and biodistribution studies in albino rats of Sprague-Dawley strain. Lipoprotein anchored dendrimeric nanoconstructs showed significant uptake by cancer cells as well as higher biodistribution of docetaxel to liver and spleen. It is concluded that these precisely synthesized engineered dendrimeric nanoconstructs could serve as promising drug carrier for fighting with the fatal disease, i.e., cancer, attributed to their defined targeting and therapeutic potential.
Lipoproteins tethered dendrimeric nanoconstructs for effective targeting to cancer cells
Energy Technology Data Exchange (ETDEWEB)
Jain, Anupriya; Jain, Keerti, E-mail: keertijain02@gmail.com; Mehra, Neelesh Kumar, E-mail: neelesh81mph@gmail.com; Jain, N. K., E-mail: dr.jnarendr@gmail.com [Dr. H. S. Gour University, Pharmaceutics Research Laboratory, Department of Pharmaceutical Sciences (India)
2013-10-15
In the present investigation, poly (propylene imine) dendrimers up to fifth generation (PPI G5.0) were synthesized using ethylene diamine and acrylonitrile. Lipoproteins (high-density lipoprotein; HDL and low-density lipoprotein; LDL) were isolated from human plasma by discontinuous density gradient ultracentrifugation, characterized and tethered to G5.0 PPI dendrimers to construct LDL- and HDL-conjugated dendrimeric nanoconstructs for tumor-specific delivery of docetaxel. Developed formulations showed sustained release characteristics in in vitro drug release and in vivo pharmacokinetic studies. The cancer targeting potential of lipoprotein coupled dendrimers was investigated by ex vivo cytotoxicity and cell uptake studies using human hepatocellular carcinoma cell lines (HepG2 cells) and biodistribution studies in albino rats of Sprague-Dawley strain. Lipoprotein anchored dendrimeric nanoconstructs showed significant uptake by cancer cells as well as higher biodistribution of docetaxel to liver and spleen. It is concluded that these precisely synthesized engineered dendrimeric nanoconstructs could serve as promising drug carrier for fighting with the fatal disease, i.e., cancer, attributed to their defined targeting and therapeutic potential.
Particle-like representation for the field of a moving point charge in nonlinear electrodynamics
International Nuclear Information System (INIS)
Gitman, D M; Shabad, A E; Shishmarev, A A
2017-01-01
In a simple nonlinear model stemming from quantum electrodynamics wherein the pointlike charge has finite field-self-energy, we demonstrate that the latter can be presented as a soliton with its energy–momentum vector satisfying the standard mechanical relation characteristic of a free moving massive relativistic particle. (paper)
Generating functional of the mean field in quantum electrodynamics with non-stable vacuum
International Nuclear Information System (INIS)
Gitman, D.M.; Kuchin, V.A.
1981-01-01
Generating functional for calculating a mean field, in the case of unstable vacuum, in quantum field theory has been suggested. Continual representation for the generating functional of the mean field has been found in the case of quantum electrodynamics with an external field. Generating electron-positron pairs from vacuum [ru
Gsponer, Andre
2009-01-01
The objective of this introduction to Colombeau algebras of generalized functions (in which distributions can be freely multiplied) is to explain in elementary terms the essential concepts necessary for their application to basic nonlinear problems in classical physics. Examples are given in hydrodynamics and electrodynamics. The problem of the…
Yang--Mills gauge theories and Baker--Johnson quantum electrodynamics
International Nuclear Information System (INIS)
Lemmon, J.; Mahanthappa, K.T.
1976-01-01
We show that the physical mass of a fermion in a symmetric asymptotically free non-Abelian vector gauge theory is dynamical in origin. We comment on the close analogy that exists between such a theory and the Baker--Johnson finite quantum electrodynamics. Comments are also made when there is spontaneous symmetry breaking
International Nuclear Information System (INIS)
Barykin, V.N.
1989-01-01
A physical interpretation of the early detected ambiguity of the electrodynamic material equations of isotropic, inertially moving media which mathematically manifests itself through complementarity of the equations invariant under the Galileo group in some cases and in other ones - under the Lorentz group that can be experimentally discovered in the aberration phenomenon and Doppler effect
Modeling the 3-DOF dynamics of an electrodynamic Maglev suspension system with a passive sled
Boeij, de J.; Gutierrez, H.M.; Agarwal, R.; Steinbuch, M.
2003-01-01
A model that describes the 3-DOF dynamics of a passively levitated electro-dynamic maglevsystem is presented. The model is based on the flux-current-force interactions and the geometricrelationships between the levitation coils and the permanent magnets on the sled. The model ispresented in a
Modeling the electromechanical interactions in a null-flux electrodynamic maglev system
Boeij, de J.; Steinbuch, M.; Gutierrez, H.M.
2005-01-01
The fundamental electromechanical interactions in a passive -flux electrodynamic maglev system (EDS) are mediated by the voltages induced in the levitation coils by the sled magnets, and by the forces exerted on the sled as a result of the induced currents. This work presents a reliable and compact
The positronium and the dipositronium in a Hartree-Fock approximation of quantum electrodynamics
DEFF Research Database (Denmark)
Sok, Jérémy Vithya
2016-01-01
The Bogoliubov-Dirac-Fock (BDF) model is a no-photon approximation of quantum electrodynamics. It allows to study relativistic electrons in interaction with the Dirac sea. A state is fully characterized by its one-body density matrix, an infinite rank non-negative projector. We prove the existence...
Quasi-potential approach to the problem of bound states in quantum electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Rizov, V A; Todorov, I T [Bylgarska Akademiya na Naukite, Sofia. Inst. za Yadrena Izsledvaniya i Yadrena Energetika
1975-07-01
The paper reviews two types of quasipotential equations. An equation with a non-local potential is derived from the equations of motion of quantum electrodynamics. It is also related to a Bethe-Salpeter type of equation for the retarded Green function. Most of the paper is devoted to a systematic study of a local version of the Logunov-Tavkhelidze quasipotential approach.
Haeringen, W. van
In view of remaining obscurities and difficulties in existing treatments of the infrared divergences in quantum electrodynamics this problem has been considered anew. The approximate model introduced in 1937 by Bloch and Nordsieck is rediscussed. It is explicitly shown to be a good substitute for
International Nuclear Information System (INIS)
Gorskij, A.S.; Ioffe, B.L.; Khodzhamiryan, A.Yu.
1989-01-01
It is shown that in massless electrodynamics (when the electron mass is strictly zero) the cross section of longitudinal photon interaction on mass shell is nonvanishing. The reasons of appearance of this effects and its possible consequences as well as analogous effects in other quantum field theories (especially non-Abelian gauge theories) are discussed. 7 refs.; 2 figs
Directory of Open Access Journals (Sweden)
A. P. Preobrazhensky
2017-02-01
Full Text Available This paper considers the problem of optimization of the characteristics of scattering of electromagnetic waves on periodic electrodynamic structure. The solution of the scattering problem is based on the method of integral equations, the optimization of the characteristics is based on the genetic algorithm. Recommendations on the parameters of the periodic structure under given angles are given.
International Nuclear Information System (INIS)
Galvao, C.A.P.; Mignaco, J.A.
1994-01-01
The classical electromagnetic theory is analysed which corresponds to the two-dimensional quantum electrodynamics with massless spinor fields (Schwinger model). The chiral anomaly is introduced as a currents property, which in the two-dimensional spinor fields are duality related. It is also shown that the resulting classical theory is consistent. (author). 5 refs
Two-dimensional quantum electrodynamics as a model in the constructive quantum field theory
International Nuclear Information System (INIS)
Ito, K.R.
1976-01-01
We investigate two-dimensional quantum electrodynamics((QED) 2 ) type models on the basis of the Hamiltonian formalism of a vector field. The transformation into a sine-Gordon equation is clarified as a generalized mass-shift transformation through canonical linear transformations. (auth.)
The potential in general linear electrodynamics. Causal structure, propagators and quantization
Energy Technology Data Exchange (ETDEWEB)
Siemssen, Daniel [Department of Mathematical Methods in Physics, Faculty of Physics, University of Warsaw (Poland); Pfeifer, Christian [Institute for Theoretical Physics, Leibniz Universitaet Hannover (Germany); Center of Applied Space Technology and Microgravity (ZARM), Universitaet Bremen (Germany)
2016-07-01
From an axiomatic point of view, the fundamental input for a theory of electrodynamics are Maxwell's equations dF=0 (or F=dA) and dH=J, and a constitutive law H=F, which relates the field strength 2-form F and the excitation 2-form H. In this talk we consider general linear electrodynamics, the theory of electrodynamics defined by a linear constitutive law. The best known application of this theory is the effective description of electrodynamics inside (linear) media (e.g. birefringence). We analyze the classical theory of the electromagnetic potential A before we use methods familiar from mathematical quantum field theory in curved spacetimes to quantize it. Our analysis of the classical theory contains the derivation of retarded and advanced propagators, the analysis of the causal structure on the basis of the constitutive law (instead of a metric) and a discussion of the classical phase space. This classical analysis sets the stage for the construction of the quantum field algebra and quantum states, including a (generalized) microlocal spectrum condition.
Processes of arbitrary order in quantum electrodynamics with a pair-creating external field
International Nuclear Information System (INIS)
Gitman, D.M.
1977-01-01
Dyson's perturbation theory analogue for quantum electrodynamical processes with arbitrary initial and final states in an external field creating pairs is discussed. The interaction with the field is taken into account exactly. The possibility of using Feynman diagrams, together with modified correspondence rules, for the representation of the above mentioned processes is demonstrated. (author)
Modeling, Design and Analysis of a Electrodynamic Levitation System by Considering the Skin Effect
Directory of Open Access Journals (Sweden)
Mohammad Rajabi Sabadani
2016-01-01
Full Text Available In this paper, lift and drag forces of permanent-magnet electrodynamic suspension (PMEDS System have been studied by considering the skin effect. Electrodynamic suspension is based on repulsive force between two magnetic fields with the same polarity. In this research the electrodynamic suspension system consists of a moving permanent magnet block levitated over a flat conducting plate with 2 mm thickness. At first, the analytical model of the PMEDS is proposed. For this propose, permanent magnet poles are modeled by the current sheets. Then the eddy current is calculated on aluminum sheet by considering the skin effect. Finally, the lift and drag forces are calculated in difference speed. The 2D finite element method is utilized to investigate the effect of speed variations on the performance of PMEDS at two different airgap. Two-dimensional finite element model, the accuracy of proposed analytical model is validated. The results of the finite element method are compared with results obtained by analytical model. It shows the accuracy of the analytical model in the estimation of the lift and drag forces of an electrodynamic suspension system.
Revisiting the tethered ureteral stents in children: a novel modification.
Kajbafzadeh, Abdol-Mohammad; Nabavizadeh, Behnam; Keihani, Sorena; Hosseini Sharifi, Seyed Hossein
2015-06-01
To propose a simple noninvasive method for ureteral stent retrieval using an extraction string sutured to the skin in children. A retrospective chart review was performed to gather relevant data from December 2005 to February 2013. After the surgeries, if indicated, a tethered double-J stent was placed in the ureter. A 5-0 non-absorbable Prolene stitch was used as an extraction string passing through the urethra and was sutured to subcoronal skin in boys or inner surface of labia majora in girls. For stent removal, a small amount of 2 % lidocaine jelly was pushed into the urethra 5 min before the procedure. The string was then pulled by continuous and gentle force until the entire stent was out. The suture was then cut to release the stent. No sedation or anesthesia was needed. A total of 378 double-J stents with extraction strings were inserted for a total of 325 patients (61.2 % male). Of the 53 patients with bilateral ureteral stents, one male patient (1.88 %) experienced early stent protrusion from urethral meatus. Two of 272 patients (0.73 %) with unilateral ureteral stent (one male and one female) encountered the same problem. All other stents were extracted successfully using the extraction string without any complications. No upward stent migration or suture site reaction was encountered. This method is a safe, easy-to-use, feasible and noninvasive alternative for cystoscopic stent removal with high success rate and minimal complications. This can lead to considerable saving in time and costs for patients, families and healthcare system.
Turbulence measurements using tethered balloon instrumentation during FIRE 1987
Hignett, Phillip
1990-01-01
As part of the surface-based observations conducted on San Nicolas Island, the U.K. Meteorological Office operated a set of turbulence probes attached to a balloon tether cable. Typically six probes were used, each capable of measuring momentum, heat, and humidity fluxes. Two probes were fitted with net radiometers, one positioned above cloud and the other below; a third probe carried a Lyman-alpha hygrometer fitted with a pre-heater for the measurement of total water content. Some preliminary results are presented from the 14th July describing the variation in structure of the cloudy boundary layer during the daytime. This day was characterized by a complete cloud cover, an inversion height of approximately 600 m. and north-westerly winds of approximately 6 m.s(-1). As an illustration the equivalent potential temperature derived from a profile ascent made between approximately 0830 and 0930 (PDT) is shown. The data has been smoothed to a height resolution of about 4 metres. At this time the cloud base was approximately 200 m. and very light drizzle was reaching the surface. The vertical velocity variance and potential temperature flux for two periods are shown; the first (shown by full lines) immediately follows the profile and the second (shown by dashed lines) is central around 1400 (PDT). The data have been normalized by their maximum values in the first period. Cloud base has now risen to approximately 300 m. There is a marked variation during the morning, particularly in sigma w. The net radiative flux above cloud top has by now reached its maximum value.
Low-Cost Propellant Launch From a Tethered Balloon
Wilcox, Brian
2006-01-01
A document presents a concept for relatively inexpensive delivery of propellant to a large fuel depot in low orbit around the Earth, for use in rockets destined for higher orbits, the Moon, and for remote planets. The propellant is expected to be at least 85 percent of the mass needed in low Earth orbit to support the NASA Exploration Vision. The concept calls for the use of many small ( 10 ton) spin-stabilized, multistage, solid-fuel rockets to each deliver 250 kg of propellant. Each rocket would be winched up to a balloon tethered above most of the atmospheric mass (optimal altitude 26 2 km). There, the rocket would be aimed slightly above the horizon, spun, dropped, and fired at a time chosen so that the rocket would arrive in orbit near the depot. Small thrusters on the payload (powered, for example, by boil-off gases from cryogenic propellants that make up the payload) would precess the spinning rocket, using data from a low-cost inertial sensor to correct for small aerodynamic and solid rocket nozzle misalignment torques on the spinning rocket; would manage the angle of attack and the final orbit insertion burn; and would be fired on command from the depot in response to observations of the trajectory of the payload so as to make small corrections to bring the payload into a rendezvous orbit and despin it for capture by the depot. The system is low-cost because the small rockets can be mass-produced using the same techniques as those to produce automobiles and low-cost munitions, and one or more can be launched from a U.S. territory on the equator (Baker or Jarvis Islands in the mid-Pacific) to the fuel depot on each orbit (every 90 minutes, e.g., any multiple of 6,000 per year).
Phenomenology of the vacuum in quantum electrodynamics and beyond
Energy Technology Data Exchange (ETDEWEB)
Doebrich, Babette
2011-09-30
Determining forces that arise by the restriction of the fluctuation modes of the vacuum by the insertion of boundaries or the observation of altered light propagation in external fields is a versatile means to investigate the vacuum structure of quantum electrodynamics. For these quantum vacuum probes, the vacuum can be understood and effectively modeled as a medium. Investigating the properties of this medium cannot only test and broaden our understanding of known interactions but can also be a valuable tool in the search for particles at low energy scales which arise in extensions of the standard model. In this thesis, we first study the geometry dependence of fluctuation modes in the Dirichlet-scalar analog of Casimir-Polder forces between an atom and a surface with arbitrary uniaxial corrugations. To this end we employ a technique which is fully nonperturbative in the height profile. We parameterize the differences to the distance dependencies in the planar limit in terms of an anomalous dimension quantifying the power-law deviation from the planar case. In numerical studies of experimentally relevant corrugations, we identify a universal regime of the anomalous dimension at larger distances. We argue that this universality arises as the relevant fluctuations average over corrugation structures smaller than the atom-wall distance. Turning to modified light propagation as a probe of the quantum vacuum, we show that a combination of strong, pulsed magnets and gravitational-wave interferometers can not only facilitate the detection of strong-field QED phenomena, but also significantly enlarges the accessible parameter space of hypothetical hidden-sector particles. We identify pulsed magnets as a suitable strong-field source to induce quantum nonlinearities, since their pulse frequency can be perfectly matched with the domain of highest sensitivity of modern gravitational-wave interferometers. Pushing current laboratory field-strengths to their limits, we suggest a
History and Flight Devleopment of the Electrodynamic Dust Shield
Johansen, Michael R.; Mackey, Paul J.; Hogue, Michael D.; Cox, Rachel E.; Phillips, James R., III; Calle, Carlos I.
2015-01-01
The surfaces of the moon, Mars, and that of some asteroids are covered with a layer of dust that may hinder robotic and human exploration missions. During the Apollo missions, for example, lunar dust caused a number of issues including vision obscuration, false instrument readings, contamination, and elevated temperatures. In fact, some equipment neared failure after only 75 hours on the lunar surface due to effects of lunar dust. NASA's Kennedy Space Center has developed an active technology to remove dust from surfaces during exploration missions. The Electrodynamic Dust Shield (EDS), which consists of a series of embedded electrodes in a high dielectric strength substrate, uses a low power, low frequency signal that produces an electric field wave that travels across the surface. This non-uniform electric field generates dielectrophoretic and electrostatic forces capable of moving dust out of these surfaces. Implementations of the EDS have been developed for solar radiators, optical systems, camera lenses, visors, windows, thermal radiators, and fabrics The EDS implementation for transparent applications (solar panels, optical systems, windows, etc.) uses transparent indium tin oxide electrodes on glass or transparent lm. Extensive testing was performed in a roughly simulated lunar environment (one-sixth gravity at 1 mPa atmospheric pressure) with lunar simulant dust. EDS panels over solar radiators showed dust removal that restored solar panel output reaching values very close to their initial output. EDS implementations for thermal radiator protection (metallic spacecraft surfaces with white thermal paint and reflective films) were also extensively tested at similar high vacuum conditions. Reflectance spectra for these types of implementations showed dust removal efficiencies in the 96% to 99% range. These tests indicate that the EDS technology is now at a Technology Readiness Level of 4 to 5. As part of EDS development, a flight version is being prepared for
Phenomenology of the vacuum in quantum electrodynamics and beyond
International Nuclear Information System (INIS)
Doebrich, Babette
2011-01-01
Determining forces that arise by the restriction of the fluctuation modes of the vacuum by the insertion of boundaries or the observation of altered light propagation in external fields is a versatile means to investigate the vacuum structure of quantum electrodynamics. For these quantum vacuum probes, the vacuum can be understood and effectively modeled as a medium. Investigating the properties of this medium cannot only test and broaden our understanding of known interactions but can also be a valuable tool in the search for particles at low energy scales which arise in extensions of the standard model. In this thesis, we first study the geometry dependence of fluctuation modes in the Dirichlet-scalar analog of Casimir-Polder forces between an atom and a surface with arbitrary uniaxial corrugations. To this end we employ a technique which is fully nonperturbative in the height profile. We parameterize the differences to the distance dependencies in the planar limit in terms of an anomalous dimension quantifying the power-law deviation from the planar case. In numerical studies of experimentally relevant corrugations, we identify a universal regime of the anomalous dimension at larger distances. We argue that this universality arises as the relevant fluctuations average over corrugation structures smaller than the atom-wall distance. Turning to modified light propagation as a probe of the quantum vacuum, we show that a combination of strong, pulsed magnets and gravitational-wave interferometers can not only facilitate the detection of strong-field QED phenomena, but also significantly enlarges the accessible parameter space of hypothetical hidden-sector particles. We identify pulsed magnets as a suitable strong-field source to induce quantum nonlinearities, since their pulse frequency can be perfectly matched with the domain of highest sensitivity of modern gravitational-wave interferometers. Pushing current laboratory field-strengths to their limits, we suggest a
Directory of Open Access Journals (Sweden)
David G Nickens
Full Text Available BACKGROUND: In vitro selection of kinase ribozymes for small molecule metabolites, such as free nucleosides, will require partition systems that discriminate active from inactive RNA species. While nucleic acid catalysis of phosphoryl transfer is well established for phosphorylation of 5' or 2' OH of oligonucleotide substrates, phosphorylation of diffusible small molecules has not been demonstrated. METHODOLOGY/PRINCIPAL FINDINGS: This study demonstrates the ability of T4 DNA ligase to capture RNA strands in which a tethered monodeoxynucleoside has acquired a 5' phosphate. The ligation reaction therefore mimics the partition step of a selection for nucleoside kinase (deoxyribozymes. Ligation with tethered substrates was considerably slower than with nicked, fully duplex DNA, even though the deoxynucleotides at the ligation junction were Watson-Crick base paired in the tethered substrate. Ligation increased markedly when the bridging template strand contained unpaired spacer nucleotides across from the flexible tether, according to the trends: A(2>A(1>A(3>A(4>A(0>A(6>A(8>A(10 and T(2>T(3>T(4>T(6 approximately T(1>T(8>T(10. Bridging T's generally gave higher yield of ligated product than bridging A's. ATP concentrations above 33 microM accumulated adenylated intermediate and decreased yields of the gap-sealed product, likely due to re-adenylation of dissociated enzyme. Under optimized conditions, T4 DNA ligase efficiently (>90% joined a correctly paired, or TratioG wobble-paired, substrate on the 3' side of the ligation junction while discriminating approximately 100-fold against most mispaired substrates. Tethered dC and dG gave the highest ligation rates and yields, followed by tethered deoxyinosine (dI and dT, with the slowest reactions for tethered dA. The same kinetic trends were observed in ligase-mediated capture in complex reaction mixtures with multiple substrates. The "universal" analog 5-nitroindole (dNI did not support ligation when
Thrust Control During Towing of Space Debris using an Elastic Tether
Directory of Open Access Journals (Sweden)
A. D. Ledkov
2014-01-01
Full Text Available The paper considers a maneuver for deorbiting the large space debris using an active spacecraft connected with the debris by an elastic tether. Tether slacking during the maneuver can lead to the tether rupture, kinking, and winding on the descending object. Therefore it is important to prevent slacking. The objective of this work is to find the law of thrust force control of the active spacecraft to ensure a continuously strained tether during the maneuver.Using Lagrange formalism a mathematical model to describe the system plane motion is developed. This model considers the active spacecraft as a mass point, the space debris as a rigid body, and the tether as a weightless elastic rod. A thrust force is directed along the local horizon of the spacecraft. Linearization of nonlinear differential equation describing longitudinal oscillations of the tether length is performed. Its phase portrait is analyzed. An approximate expression describing the position of the center on the phase portrait is obtained. A time-optimal control with full feedback to ensure that the tether is in the strained state is found by solving the Bellman equation. To use the obtained optimal law it is necessary to set the measuring equipment on the spacecraft, which is capable of accurate measuring a distance to the space debris and its relative velocity. An alternative control law, which is simpler in terms of the practical implementation, is proposed. As an example, the descent from an orbit of nonfunctioning Soviet satellite Meteor-2 is considered. It is shown that both proposed laws provide continuous strain of the tether during deorbiting of the satellite. Moreover, slack does not occur even at the first period of oscillation of the tether length. It is shown that the use of the proposed control laws leads to slight increase of deorbiting time as compared to the case of using the constant thrust.The results can be used to develop the control systems of small spacecrafts
A tethering complex drives the terminal stage of SNARE-dependent membrane fusion
D'Agostino, Massimo; Risselada, Herre Jelger; Lürick, Anna; Ungermann, Christian; Mayer, Andreas
2017-11-01
Membrane fusion in eukaryotic cells mediates the biogenesis of organelles, vesicular traffic between them, and exo- and endocytosis of important signalling molecules, such as hormones and neurotransmitters. Distinct tasks in intracellular membrane fusion have been assigned to conserved protein systems. Tethering proteins mediate the initial recognition and attachment of membranes, whereas SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) protein complexes are considered as the core fusion engine. SNARE complexes provide mechanical energy to distort membranes and drive them through a hemifusion intermediate towards the formation of a fusion pore. This last step is highly energy-demanding. Here we combine the in vivo and in vitro fusion of yeast vacuoles with molecular simulations to show that tethering proteins are critical for overcoming the final energy barrier to fusion pore formation. SNAREs alone drive vacuoles only into the hemifused state. Tethering proteins greatly increase the volume of SNARE complexes and deform the site of hemifusion, which lowers the energy barrier for pore opening and provides the driving force. Thereby, tethering proteins assume a crucial mechanical role in the terminal stage of membrane fusion that is likely to be conserved at multiple steps of vesicular traffic. We therefore propose that SNAREs and tethering proteins should be considered as a single, non-dissociable device that drives fusion. The core fusion machinery may then be larger and more complex than previously thought.
Yu, Guihua; Kushwaha, Amit; Lee, Jungkyu K; Shaqfeh, Eric S G; Bao, Zhenan
2011-01-25
DNA has been recently explored as a powerful tool for developing molecular scaffolds for making reproducible and reliable metal contacts to single organic semiconducting molecules. A critical step in the process of exploiting DNA-organic molecule-DNA (DOD) array structures is the controlled tethering and stretching of DNA molecules. Here we report the development of reproducible surface chemistry for tethering DNA molecules at tunable density and demonstrate shear flow processing as a rationally controlled approach for stretching/aligning DNA molecules of various lengths. Through enzymatic cleavage of λ-phage DNA to yield a series of DNA chains of various lengths from 17.3 μm down to 4.2 μm, we have investigated the flow/extension behavior of these tethered DNA molecules under different flow strengths in the flow-gradient plane. We compared Brownian dynamic simulations for the flow dynamics of tethered λ-DNA in shear, and found our flow-gradient plane experimental results matched well with our bead-spring simulations. The shear flow processing demonstrated in our studies represents a controllable approach for tethering and stretching DNA molecules of various lengths. Together with further metallization of DNA chains within DOD structures, this bottom-up approach can potentially enable efficient and reliable fabrication of large-scale nanoelectronic devices based on single organic molecules, therefore opening opportunities in both fundamental understanding of charge transport at the single molecular level and many exciting applications for ever-shrinking molecular circuits.
Alsamhi, Saeed H; Samar Ansari, Mohd; Rajput, Navin S
2018-04-01
A disaster is a consequence of natural hazards and terrorist acts, which have significant potential to disrupt the entire wireless communication infrastructure. Therefore, the essential rescue squads and recovery operations during a catastrophic event will be severely debilitated. To provide efficient communication services, and to reduce casualty mortality and morbidity during the catastrophic events, we proposed the Tethered Balloon technology for disaster preparedness, detection, mitigation, and recovery assessment. The proposed Tethered Balloon is applicable to any type of disaster except for storms. The Tethered Balloon is being actively researched and developed as a simple solution to improve the performance of rescues, facilities, and services of emergency medical communication in the disaster area. The most important requirement for rescue and relief teams during or after the disaster is a high quality of service of delivery communication services to save people's lives. Using our proposed technology, we report that the Tethered Balloon has a large disaster coverage area. Therefore, the rescue and research teams are given higher priority, and their performance significantly improved in the particular coverage area. Tethered Balloon features made it suitable for disaster preparedness, mitigation, and recovery. The performance of rescue and relief teams was effective and efficient before and after the disaster as well as can be continued to coordinate the relief teams until disaster recovery. (Disaster Med Public Health Preparedness. 2018;12:222-231).
Poirier, Luke A; Gilbert, Shane T C; St-Hilaire, Sophie; Davidson, Jeff; Cox, Ruth; Quijón, Pedro A
2018-02-01
Tethering assays, or the physical restraint of test organisms, has been used in the past to measure selected organisms' response to stressors while removing the observer from the experimental setting. Although informative for monitoring and hypothesis testing, these assays often used microfilaments that have been found to be too invasive or prone to biases given their effects on test organisms' behavior. Here, we describe a new variation of tethering using American oysters (Crassostrea virginica) and illustrate its use in the study of their mortality rates as a result of two stressors: siltation and predation by a non-indigenous species. Our protocol identified a resistant (non-toxic) glue that could be used to attach oysters to stone slabs, thus partially mimicking the natural cementation of the shell to natural substrates. This variation of tethering was harmless and maintained oysters' body position and natural ability to filter feed. Using tethered oysters in separate two-week field cage experiments, we also show how siltation and predation by a non-indigenous species (the European green crab, Carcinus maenas), caused a gradual, easily measurable increase in oyster mortality rates. We argue that this variation of tethering is a cost-effective and advantageous way to monitor or test the effects of these and other stressors on oysters and similar species. Copyright © 2017 Elsevier Ltd. All rights reserved.
Observing Formation of Flux Rope by Tether-cutting Reconnection in the Sun
Energy Technology Data Exchange (ETDEWEB)
Xue, Zhike; Yan, Xiaoli; Yang, Liheng; Wang, Jincheng; Zhao, Li, E-mail: zkxue@ynao.ac.cn [Yunnan Observatories, Chinese Academy of Sciences, Kunming Yunnan 650216 (China)
2017-05-10
Tether-cutting reconnection is considered as one mechanism for the formation of a flux rope. It has been proposed for more than 30 years; however, so far, direct observations of it are very rare. In this Letter, we present observations of the formation of a flux rope via tether-cutting reconnection in NOAA AR 11967 on 2014 February 2 by combining observations with the New Vacuum Solar Telescope and the Solar Dynamic Observatory . The tether-cutting reconnection occurs between two sets of highly sheared magnetic arcades. Comprehensive observational evidence of the reconnection is as follows: changes of the connections between the arcades, brightenings at the reconnection site, hot outflows, formation of a flux rope, slow-rise motion of the flux rope, and flux cancelation. The outflows are along three directions from the reconnection site to the footpoints with the velocities from 24 ± 1 km s{sup −1} to 69 ± 5 km s{sup −1}. Additionally, it is found that the newly formed flux rope connects far footpoints and has a left-handed twisted structure with many fine threads and a concave-up-shape structure in the middle. All the observations are in agreement with the tether-cutting model and provide evidence that tether-cutting reconnection leads to the formation of the flux rope associated with flux shear flow and cancelation.
Energy Technology Data Exchange (ETDEWEB)
Sund, James B., E-mail: jim@jamessund.com [Department of Electrical and Computer Engineering, Duke University, Durham, NC (United States); Causey, Corey P. [Departments of Chemistry and Biochemistry, Duke University, Durham, NC (United States); Wolter, Scott D. [Department of Physics, Elon University, Elon, NC 27244 (United States); Parker, Charles B., E-mail: charles.parker@duke.edu [Department of Electrical and Computer Engineering, Duke University, Durham, NC (United States); Stoner, Brian R. [Department of Electrical and Computer Engineering, Duke University, Durham, NC (United States); Research Triangle Institute (RTI) International, Research Triangle Park, NC (United States); Toone, Eric J. [Departments of Chemistry and Biochemistry, Duke University, Durham, NC (United States); Glass, Jeffrey T. [Department of Electrical and Computer Engineering, Duke University, Durham, NC (United States)
2014-05-01
Highlights: • Diamond surfaces were functionalized with organic molecules using a novel approach. • Used biomimicry to select a molecule to bind NO, similar to the human body. • Molecular orbital theory predicted the molecule-analyte oxidation behavior. • A thiol moiety was attached to an amine surface tether on the diamond surface. • XPS analysis verified each surface functionalization step. - Abstract: The surface of conducting diamond was functionalized with a terminal thiol group that is capable of binding and detecting nitrogen–oxygen species. The functionalization process employed multiple steps starting with doped diamond films grown by plasma enhanced chemical vapor deposition followed by hydrogen termination and photochemical attachment of a chemically protected amine alkene. The surface tether was deprotected to reveal the amine functionality, which enabled the tether to be extended with surface chemistry to add a terminal thiol moiety for electrochemical sensing applications. Each step of the process was validated using X-ray photoelectron spectroscopy analysis.
International Nuclear Information System (INIS)
Sund, James B.; Causey, Corey P.; Wolter, Scott D.; Parker, Charles B.; Stoner, Brian R.; Toone, Eric J.; Glass, Jeffrey T.
2014-01-01
Highlights: • Diamond surfaces were functionalized with organic molecules using a novel approach. • Used biomimicry to select a molecule to bind NO, similar to the human body. • Molecular orbital theory predicted the molecule-analyte oxidation behavior. • A thiol moiety was attached to an amine surface tether on the diamond surface. • XPS analysis verified each surface functionalization step. - Abstract: The surface of conducting diamond was functionalized with a terminal thiol group that is capable of binding and detecting nitrogen–oxygen species. The functionalization process employed multiple steps starting with doped diamond films grown by plasma enhanced chemical vapor deposition followed by hydrogen termination and photochemical attachment of a chemically protected amine alkene. The surface tether was deprotected to reveal the amine functionality, which enabled the tether to be extended with surface chemistry to add a terminal thiol moiety for electrochemical sensing applications. Each step of the process was validated using X-ray photoelectron spectroscopy analysis
Measurement of calcium influx in tethered rings of rabbit aorta under tension
International Nuclear Information System (INIS)
Gleason, M.M.; Ratz, P.H.; Flaim, S.F.
1985-01-01
Calcium (Ca) influx in vascular smooth muscle is routinely measured in untethered preparations not under passive stretch, and Ca influx data are correlated with data for steady-state isometric tension obtained under parallel conditions from tethered preparations under passive stretch. The validity of this method was tested by simultaneous measurement of Ca influx and tension in tethered rings of rabbit thoracic aorta. Ca influx ( 45 Ca 3-min pulse) and tension were measured at 3 and 30 min after norepinephrine (NE) or KCl and under control (no agonist) conditions. Active tension was significantly altered by variations in passive tension. Ca influx was unaffected by passive tension under control, NE, or KCl conditions, and results were similar at 3 and 30 min. The results confirm the validity of correlating Ca influx data from untethered rings with steady-state contractile response data obtained from tethered rings under similar experimental conditions
Manipulating neuronal circuits with endogenous and recombinant cell-surface tethered modulators
Directory of Open Access Journals (Sweden)
Mandë Holford
2009-10-01
Full Text Available Neuronal circuits depend on the precise regulation of cell-surface receptors and ion channels. An ongoing challenge in neuroscience research is deciphering the functional contribution of specific receptors and ion channels using engineered modulators. A novel strategy, termed “tethered toxins”, was recently developed to characterize neuronal circuits using the evolutionary derived selectivity of venom peptide toxins and endogenous peptide ligands, such as lynx1 prototoxins. Herein, the discovery and engineering of cell-surface tethered peptides is reviewed, with particular attention given to their cell-autonomy, modular composition, and genetic targeting in different model organisms. The relative ease with which tethered peptides can be engineered, coupled with the increasing number of neuroactive venom toxins and ligand peptides being discovered, imply a multitude of potentially innovative applications for manipulating neuronal circuits and tissue-specific cell networks, including treatment of disorders caused by malfunction of receptors and ion channels.
Stability analysis and trend study of a balloon tethered in a wind, with experimental comparisons
Redd, L. T.; Bland, S. R.; Bennett, R. M.
1973-01-01
A stability analysis and trend study for a balloon tethered in a steady wind are presented. The linearized, stability-derivative type analysis includes balloon aerodynamics, buoyancy, mass (including apparent mass), and static forces resulting from the tether cable. The analysis has been applied to a balloon 7.64 m in length, and the results are compared with those from tow tests of this balloon. This comparison shows that the analysis gives reasonable predictions for the damping, frequencies, modes of motion, and stability boundaries exhibited by the balloon. A trend study for the 7.64-m balloon was made to illustrate how the stability boundaries are affected by changes in individual stability parameters. The trends indicated in this study may also be applicable to many other tethered-balloon systems.
Bennett, R. M.; Bland, S. R.; Redd, L. T.
1973-01-01
Computer programs for calculating the stability characteristics of a balloon tethered in a steady wind are presented. Equilibrium conditions, characteristic roots, and modal ratios are calculated for a range of discrete values of velocity for a fixed tether-line length. Separate programs are used: (1) to calculate longitudinal stability characteristics, (2) to calculate lateral stability characteristics, (3) to plot the characteristic roots versus velocity, (4) to plot the characteristic roots in root-locus form, (5) to plot the longitudinal modes of motion, and (6) to plot the lateral modes for motion. The basic equations, program listings, and the input and output data for sample cases are presented, with a brief discussion of the overall operation and limitations. The programs are based on a linearized, stability-derivative type of analysis, including balloon aerodynamics, apparent mass, buoyancy effects, and static forces which result from the tether line.
Lawson, P.; Stamnes, K.; Stamnes, J.; Zmarzly, P.; O'Connor, D.; Koskulics, J.; Hamre, B.
2008-12-01
A tethered balloon system specifically designed to collect microphysical data in mixed-phase clouds was deployed in Arctic stratus clouds during May 2008 near Ny-Alesund, Svalbard, at 79 degrees North Latitude. This is the first time a tethered balloon system with a cloud particle imager (CPI) that records high-resolution digital images of cloud drops and ice particles has been operated in cloud. The custom tether supplies electrical power to the instrument package, which in addition to the CPI houses a 4-pi short-wavelength radiometer and a met package that measures temperature, humidity, pressure, GPS position, wind speed and direction. The instrument package was profiled vertically through cloud up to altitudes of 1.6 km. Since power was supplied to the instrument package from the ground, it was possible to keep the balloon package aloft for extended periods of time, up to 9 hours at Ny- Ålesund, which was limited only by crew fatigue. CPI images of cloud drops and the sizes, shapes and degree of riming of ice particles are shown throughout vertical profiles of Arctic stratus clouds. The images show large regions of mixed-phase cloud from -8 to -2 C. The predominant ice crystal habits in these regions are needles and aggregates of needles. The amount of ice in the mixed-phase clouds varied considerably and did not appear to be a function of temperature. On some occasions, ice was observed near cloud base at -2 C with supercooled cloud above to - 8 C that was devoid of ice. Measurements of shortwave radiation are also presented. Correlations between particle distributions and radiative measurements will be analyzed to determine the effect of these Arctic stratus clouds on radiative forcing.
Differential Regulation of Synaptic Vesicle Tethering and Docking by UNC-18 and TOM-1.
Gracheva, Elena O; Maryon, Ed B; Berthelot-Grosjean, Martine; Richmond, Janet E
2010-01-01
The assembly of SNARE complexes between syntaxin, SNAP-25 and synaptobrevin is required to prime synaptic vesicles for fusion. Since Munc18 and tomosyn compete for syntaxin interactions, the interplay between these proteins is predicted to be important in regulating synaptic transmission. We explored this possibility, by examining genetic interactions between C. elegans unc-18(Munc18), unc-64(syntaxin) and tom-1(tomosyn). We have previously demonstrated that unc-18 mutants have reduced synaptic transmission, whereas tom-1 mutants exhibit enhanced release. Here we show that the unc-18 mutant release defect is associated with loss of two morphologically distinct vesicle pools; those tethered within 25 nm of the plasma membrane and those docked with the plasma membrane. In contrast, priming defective unc-13 mutants accumulate tethered vesicles, while docked vesicles are greatly reduced, indicating tethering is UNC-18-dependent and occurs in the absence of priming. C. elegans unc-64 mutants phenocopy unc-18 mutants, losing both tethered and docked vesicles, whereas overexpression of open syntaxin preferentially increases vesicle docking, suggesting UNC-18/closed syntaxin interactions are responsible for vesicle tethering. Given the competition between vertebrate tomosyn and Munc18, for syntaxin binding, we hypothesized that C. elegans TOM-1 may inhibit both UNC-18-dependent vesicle targeting steps. Consistent with this hypothesis, tom-1 mutants exhibit enhanced UNC-18 plasma membrane localization and a concomitant increase in both tethered and docked synaptic vesicles. Furthermore, in tom-1;unc-18 double mutants the docked, primed vesicle pool is preferentially rescued relative to unc-18 single mutants. Together these data provide evidence for the differential regulation of two vesicle targeting steps by UNC-18 and TOM-1 through competitive interactions with syntaxin.
Unilateral pedicle screws asymmetric tethering: an innovative method to create idiopathic deformity
Directory of Open Access Journals (Sweden)
Zhang Xuesong
2007-10-01
Full Text Available Abstract Objective To evaluate the feasibility of the method that unilateral pedicle screws asymmetric tethering in concave side in combination with convex rib resection for creating idiopathic deformity. Summary of background data Various methods are performed to create idiopathic deformity. Among these methods, posterior asmmetric tethering of the spine shows satisfying result, but some drawbacks related to the current posterior asymmetric tether were still evident. Materials and methods Unilateral pedicle screws asymmetric tethering was performed to 14 female goats (age: 5–8 week-old, weight: 6–8 kg in concave side in combination with convex rib resection. Dorsoventral and lateral plain radiographs were taken of each thoracic spine in the frontal and sagittal planes right after the surgery and later every 4 weeks. Results All animals ambulated freely after surgery. For technical reasons, 2 goats were excluded (one animal died for anesthetic during the surgery, and one animal was lost for instrumental fail due to postoperative infection. Radiography showed that 11 goats exhibited scoliosis with convex toward to the right side, and as the curve increased with time, only 1 goat showed nonprogressive. The initial scoliosis generated in the progressors after the procedures measured 29.0° on average (range 23.0°–38.5° and increased to 43.0° on average (range 36.0°–58.0° over 8 to 10 weeks. The average progression of 14.0° was measured. The curvature immediately after tethering surgery (the initial Cobb angle did have a highly significant correlation with the final curvature (p Conclusion Unilateral pedicle screws asymmetric tethering is a practical method to create experimental scoliosis, especially for those who would like to study the correction of this deformity.
Differential regulation of synaptic vesicle tethering and docking by UNC-18 and TOM-1
Directory of Open Access Journals (Sweden)
Elena O Gracheva
2010-10-01
Full Text Available The assembly of SNARE complexes between syntaxin, SNAP-25 and synaptobrevin is required to prime synaptic vesicles for fusion. Since Munc18 and tomosyn compete for syntaxin interactions, the interplay between these proteins is predicted to be important in regulating synaptic transmission. We explored this possibility, by examining genetic interactions between C. elegans unc-18(Munc18, unc-64(syntaxin and tom-1(tomosyn. We have previously demonstrated that unc-18 mutants have reduced synaptic transmission, whereas tom-1 mutants exhibit enhanced release. Here we show that the unc-18 mutant release defect is associated with loss of two morphologically distinct vesicle pools; those tethered within 25nm of the plasma membrane and those docked with the plasma membrane. In contrast, priming defective unc-13 mutants accumulate tethered vesicles, while docked vesicles are greatly reduced, indicating tethering is UNC-18-dependent and occurs in the absence of priming. C. elegans unc-64 mutants phenocopy unc-18 mutants, losing both tethered and docked vesicles, whereas overexpression of open syntaxin preferentially increases vesicle docking, suggesting UNC-18/closed syntaxin interactions are responsible for vesicle tethering. Given the competition between vertebrate tomosyn and Munc18, for syntaxin binding, we hypothesized that C. elegans TOM-1 may inhibit both UNC-18-dependent vesicle targeting steps. Consistent with this hypothesis, tom-1 mutants exhibit enhanced UNC-18 plasma membrane localization and a concomitant increase in both tethered and docked synaptic vesicles. Furthermore, in tom-1;unc-18 double mutants the docked, primed vesicle pool is preferentially rescued relative to unc-18 single mutants. Together these data provide evidence for the differential regulation of two vesicle targeting steps by UNC-18 and TOM-1 through competitive interactions with syntaxin
BOU: Development of a low-cost tethered balloon sensing system for monitoring the lower atmosphere
Picos, Rodrigo; Lopez-Grifol, Alvaro; Martinez-Villagrassa, Daniel; Simó, Gemma; Wenger, Burkhard; Dünnermann, Jens; Jiménez, Maria Antonia; Cuxart, Joan
2016-04-01
The study of the atmospheric boundary layer, the lowest part of the atmosphere, and the processes that occur therein often requires the observation of vertical profiles of the main meteorological variables, i.e. air temperature and humidity, wind vector and barometric pressure. In particular, when the interest is focused on the air-surface interactions, a high vertical resolution over the first 500 m is required for the observations to describe the physical processes that occur immediately above the surface. Typically, these needs are covered with the use of captive balloons, which are helium-filled balloons tethered to a winch on the ground and a sensor package suspended a short distance below the balloon. Since the commercial version of such instrumental platforms are scarce and expensive, a new low-cost device has been developed in the last years: BOU (tethered Balloon sonde OWL-UIB). In this paper, we focus on the sensor package and data acquisition system part, that is able to fulfill the low-cost requirements. The system uses a low-cost Arduino Mega board as the processor, and stores all the data in a SD card, though an RF connection is also possible but more unreliable. The system has been configured to sample temperature, humidity, air pressure, wind speed, having also a magnetometer and an accelerometer. Sampling time was 1 second, though it was possible to set it faster. It is worth mentioning that the system is easily reconfigurable, and more sensors can be added. The system is powered by a Polymer battery of 1800mA , allowing the system to run continously for more than 6 hours. The temperature is acquired using three different sensors (a HYT 271 calibrated sensor with an accuracy of ±0.2 °C, plus the internal temperature sensors of the wind and pressure sensors, with accuracies around ±0.5 °C). The humidity is also sensed using the calibrated HYT 271 sensor, which features an accuracy of ±1.8%. Air pressure is sensed using a BMP080 sensor, which
Sund, James B.; Causey, Corey P.; Wolter, Scott D.; Parker, Charles B.; Stoner, Brian R.; Toone, Eric J.; Glass, Jeffrey T.
2014-05-01
The surface of conducting diamond was functionalized with a terminal thiol group that is capable of binding and detecting nitrogen-oxygen species. The functionalization process employed multiple steps starting with doped diamond films grown by plasma enhanced chemical vapor deposition followed by hydrogen termination and photochemical attachment of a chemically protected amine alkene. The surface tether was deprotected to reveal the amine functionality, which enabled the tether to be extended with surface chemistry to add a terminal thiol moiety for electrochemical sensing applications. Each step of the process was validated using X-ray photoelectron spectroscopy analysis.
Electromechanical engineering in SnO2 nanoparticle tethered hybrid ionic liquid
Deb, Debalina; Bhattacharya, Subhratanu
2017-05-01
Challenge of developing electrolytes comprising synergic properties of high mechanical strength with superior electrical and electrochemical properties has so far been unmet towards the application of secondary storage devices. In this research, we have engineered the electromechanical properties of 2-(trimethylamino) ethyl methacrylate bis(trifluoromethylsulfonyl) imide [TMEM]TFSI ionic liquid by tethering silane modified SnO2 nanoparticles within it. Different percentages of tethering are employed to achieve improved ionic conductivity, better discharge/ charging ratio (40%) along with gel like mechanical properties. Our findings appear to provide an optimal solution towards the future prospects in application in a number of areas, notably in energy-related technologies.