scholarly journals Unfolding conformal geometry

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Euihun Joung ◽  
Min-gi Kim ◽  
Yujin Kim
Keyword(s):  
Conformal Geometry ◽  
Type B ◽  
Nonlinear Structure ◽  
First Order ◽  
Gravitational Systems ◽  
Algebraic Constraints ◽  
Invariant Densities

Abstract Conformal geometry is studied using the unfolded formulation à la Vasiliev. Analyzing the first-order consistency of the unfolded equations, we identify the content of zero-forms as the spin-two off-shell Fradkin-Tseytlin module of $$ \mathfrak{so}\left(2,d\right) $$ so 2 d . We sketch the nonlinear structure of the equations and explain how Weyl invariant densities, which Type-B Weyl anomaly consist of, could be systematically computed within the unfolded formulation. The unfolded equation for conformal geometry is also shown to be reduced to various on-shell gravitational systems by requiring additional algebraic constraints.

An inertial piezoelectric hybrid actuator with large angular velocity and high resolution

2019 ◽  
Vol 30 (14) ◽  
pp. 2099-2111 ◽  
Author(s):  
Huilu Bao ◽  
Jianming Wen ◽  
Kang Chen ◽  
Jijie Ma ◽  
Dan Lei ◽  
...  
Keyword(s):  
High Resolution ◽  
Angular Velocity ◽  
Natural Frequencies ◽  
Angular Displacement ◽  
High Accuracy ◽  
Laser Vibrometer ◽  
Type B ◽  
First Order ◽  
Offset Distance ◽  
Hybrid Actuator

This article proposes an inertial piezoelectric actuator with hybrid design of asymmetrically clamping structures and a bias unit for the achievement of large angular velocity and high resolution. To investigate the influence of asymmetrical clamp and bias unit on the driving performance, two types of actuators were fabricated and tested. Combined effects from asymmetrical clamp and bias unit contribute to type A, while their subtractive effect is applied to type B. Using a scanning laser vibrometer, experiments were conducted to analyze the characteristics of the angular displacement and corresponding velocity. It is indicated that the measured first-order natural frequencies for above two types are 13.828 and 14.141 Hz, which agrees well with the simulation results of 16.666 and 17.379 Hz, respectively. Besides, compared with the actuators with simple asymmetrical clamping structure or bias unit, this hybrid actuator can obtain an angular velocity 6.87 rad/s at 80 V and 16 Hz and a resolution of 2.80 μrad under a square signal of 20 V and 1 Hz and an offset distance of −22 mm. As a result, the proposed actuators can achieve large angular velocity and high resolution, which is potentially applicable to quick positioning with high accuracy.

Transonic equivalence rule: a nonlinear problem involving lift

1975 ◽  
Vol 72 (1) ◽  
pp. 161-187 ◽  
Author(s):  
H. K. Cheng ◽  
M. M. Hafez
Keyword(s):  
Transonic Flow ◽  
Line Source ◽  
Sectional Area ◽  
Small Disturbance ◽  
Cross Sectional ◽  
Outer Flow ◽  
Nonlinear Structure ◽  
First Order ◽  
Lift Control ◽  
Area Rule

The inviscid transonic flow past a thin wing having swept leading edges, with smooth lift and thickness distributions, is shown to possess an outer nonlinear structure determined principally by a line source and a line doublet. Three domains (the thickness-dominated, the intermediate, and the lift-dominated), representing different degrees of lift control of the outer flow, are identified; a transonic equivalence rule valid in all three domains is established. Except in one domain, departure from the Whitcomb-Oswatitsch area rule is significant; the equivalent body corresponding to the source effect has an increased cross-sectional area depending nonlinearly on the lift. This nonlinear lift contribution results from the second-order corrections to the inner (Jones) solution, but produces effects of first-order importance in the outer flow. Of interest is an afterbody effect dependent on the vortex drag, which is not accounted for by the classical transonic small-disturbance theory.

scholarly journals Semiclassical bosonic D-brane boundary states in curved spacetime

Open Physics ◽  
2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Ion Vancea
Keyword(s):  
Gravitational Field ◽  
Center Of Mass ◽  
Quantization Method ◽  
Strong Gravitational Field ◽  
First Order ◽  
Boundary States ◽  
Spacetime Metric ◽  
Algebraic Constraints ◽  
Semiclassical State ◽  
First Order Perturbation

AbstractIn this paper we discuss the existence of quantum D-brane states in the strong gravitational field and in the presence of a constant Kalb-Ramond field. A semiclassical string quantization method in which the spacetime metric g AB and the constant antisymmetric Kalb-Ramond field b AB are treated exactly is employed. In this framework, the semiclassical D-branes are defined at the first order perturbation around the trajectory of the center-of-mass of a string. The set of equations the semiclassical D-branes must satisfy in a general strong gravitational field are given. These equations are solved in the AdS background where it is shown that a D-brane coherent state exists if the operators that project the string fields onto the corresponding Neumann and Dirichlet directions satisfy a set of algebraic constraints. A second set of equations that should be satisfied by the projectors in order that the semiclassical state be compatible with the global structure of the D-brane are derived in the particle limit of a string in the torsionless AdS background.

FIRST ORDER ACTIONS FOR GRAVITATIONAL SYSTEMS, STRINGS AND MEMBRANES

1988 ◽  
Vol 03 (10) ◽  
pp. 2401-2416 ◽  
Author(s):  
U. LINDSTRÖM
Keyword(s):  
Lagrange Multipliers ◽  
Two Dimensions ◽  
First Order ◽  
Gravitational Theories ◽  
Gravitational Systems

We discuss first order actions in general and the construction of first order actions by eliminating Lagrange multipliers in particular. A number of first order actions for gravitational theories are presented. Part of the article reviews first order actions, some of them well-known and some lesser known. New examples of first order actions include Weyl-invariant actions for membranes, with and without rigidity terms, as well as for Abelian and non-Abelian Born-Infeld actions in two dimensions.

scholarly journals Explicitly solvable systems of two autonomous first-order Ordinary Differential Equations with homogeneous quadratic right-hand sides

2021 ◽  
Author(s):  
Francesco Calogero ◽  
Farrin Payandeh
Keyword(s):  
Differential Equations ◽  
Ordinary Differential Equations ◽  
A Priori ◽  
Nonlinear Odes ◽  
First Order ◽  
Right Hand ◽  
Algebraic Constraints ◽  
Special Case

After tersely reviewing the various meanings that can be given to the property of a system of nonlinear ODEs to be solvable, we identify a special case of the system of two first-order ODEs with homogeneous quadratic right-hand sides which is explicitly solvable. It is identified by 2 explicit algebraic constraints on the 6 a priori arbitrary parameters that characterize this system. Simple extensions of this model to cases with nonhomogeneous quadratic right-hand sides are also identified, including isochronous cases

Dual systems for all: Higher-order, role-based relational reasoning as a uniquely derived feature of human cognition

2019 ◽  
Vol 42 ◽  
Author(s):  
Daniel J. Povinelli ◽  
Gabrielle C. Glorioso ◽  
Shannon L. Kuznar ◽  
Mateja Pavlic
Keyword(s):  
Temporal Reasoning ◽  
Higher Order ◽  
Important Case ◽  
Human Cognition ◽  
Relational Reasoning ◽  
Dual Systems ◽  
First Order ◽  
Reasoning System ◽  
Role Based

Abstract Hoerl and McCormack demonstrate that although animals possess a sophisticated temporal updating system, there is no evidence that they also possess a temporal reasoning system. This important case study is directly related to the broader claim that although animals are manifestly capable of first-order (perceptually-based) relational reasoning, they lack the capacity for higher-order, role-based relational reasoning. We argue this distinction applies to all domains of cognition.

Stochasting modeling of planetary ring systems

1984 ◽  
Vol 75 ◽  
pp. 461-469 ◽  
Author(s):  
Robert W. Hart
Keyword(s):  
Maximum Entropy ◽  
Ring System ◽  
The Sun ◽  
Ultimate State ◽  
Interparticle Interactions ◽  
Ring Systems ◽  
First Order ◽  
Planetary Ring ◽  
Insight Into

ABSTRACTThis paper models maximum entropy configurations of idealized gravitational ring systems. Such configurations are of interest because systems generally evolve toward an ultimate state of maximum randomness. For simplicity, attention is confined to ultimate states for which interparticle interactions are no longer of first order importance. The planets, in their orbits about the sun, are one example of such a ring system. The extent to which the present approximation yields insight into ring systems such as Saturn's is explored briefly.

Biological and Morphological Studies on Low-Leukemia-Strain Mice with Hodgkin's-Like Neoplasia Induced by Serial Cell-Free Transmission of Leukemic Organs of SJL/J Strain Mice

1968 ◽  
Vol 26 ◽  
pp. 210-211
Author(s):  
S. Fujinaga ◽  
K. Maruyama ◽  
C.W. Williams ◽  
K. Sekhri ◽  
L. Dmochowski
Keyword(s):  
Tissue Culture ◽  
Type A ◽  
Reticulum Cell ◽  
Type B ◽  
Viral Origin ◽  
Serial Transfer ◽  
Strain Mouse ◽  
Morphological Studies ◽  
Cell Neoplasm ◽  
Free Material

Yumoto and Dmochowski (Cancer Res.27, 2098 (1967)) reported the presence of mature and immature type C leukemia virus particles in leukemic organs and tissues such as lymph nodes, spleen, thymus, liver, and kidneys of SJL/J strain mice with Hodgki's-like disease or reticulum cell neoplasm (type B). In an attempt to ascertain the possibility that this neoplasia may be of viral origin, experiments with induction and transmission of this neoplasm were carried out using cell-free extracts of leukemic organs from an SJL/J strain mouse with spontaneous disease.It has been possible to induce the disease in low-leukemia BALB/c and C3HZB strain mice and serially transfer the neoplasia by cell-free extracts of leukemic organs of these mice. Histological examination revealed the neoplasia to be of either reticulum cell-type A or type B. Serial transfer is now in its fifth passage. In addition leukemic spleen from another SJL/J strain mouse with spontaneous reticulum cell neoplasm (type A) was set up in tissue culture and is now in its 141st serial passage in vitro. Preliminary results indicate that cell-free material of 39th tissue culture passage can reproduce neoplasia in BALB/c mice.

Cryo-electron microscopy of two-dimensional crystals of reduced type B botulinum neurotoxin

1992 ◽  
Vol 50 (1) ◽  
pp. 530-531
Author(s):  
P. F. Flicker ◽  
V.S. Kulkarni ◽  
J. P. Robinson ◽  
G. Stubbs ◽  
B. R. DasGupta
Keyword(s):  
Disulfide Bonds ◽  
Clostridium Botulinum ◽  
Structural Changes ◽  
Two Dimensional ◽  
Type B ◽  
Single Chain ◽  
Muscle Paralysis ◽  
Cryo Electron Microscopy ◽  
Disulfide Linkages ◽  
Intracellular Action

Botulinum toxin is a potent neurotoxin produced by Clostridium botulinum. The toxin inhibits release of neurotransmitter, causing muscle paralysis. There are several serotypes, A to G, all of molecular weight about 150,000. The protein exists as a single chain or or as two chains, with two disulfide linkages. In a recent investigation on intracellular action of neurotoxins it was reported that type B neurotoxin can inhibit the release of Ca++-activated [3H] norepinephrine only if the disulfide bonds are reduced. In order to investigate possible structural changes in the toxin upon reduction of the disulfide bonds, we have prepared two-dimensional crystals of reduced type B neurotoxin. These two-dimensional crystals will be compared with those of the native (unreduced) type B toxin.

Morphological studies of linear (AB)n multiblock copolymers and their blends

1992 ◽  
Vol 50 (1) ◽  
pp. 384-385
Author(s):  
Richard J. Spontak ◽  
Steven D. Smith ◽  
Arman Ashraf
Keyword(s):  
Electron Microscopy ◽  
Microphase Separation ◽  
Multiblock Copolymers ◽  
First Order ◽  
Morphological Studies ◽  
Transmission Electron ◽  
First Order Phase Transition ◽  
Covalently Bonded ◽  
Total Molecular Weight ◽  
First Order Phase

Block copolymers are composed of sequences of dissimilar chemical moieties covalently bonded together. If the block lengths of each component are sufficiently long and the blocks are thermodynamically incompatible, these materials are capable of undergoing microphase separation, a weak first-order phase transition which results in the formation of an ordered microstructural network. Most efforts designed to elucidate the phase and configurational behavior in these copolymers have focused on the simple AB and ABA designs. Few studies have thus far targeted the perfectly-alternating multiblock (AB)n architecture. In this work, two series of neat (AB)n copolymers have been synthesized from styrene and isoprene monomers at a composition of 50 wt% polystyrene (PS). In Set I, the total molecular weight is held constant while the number of AB block pairs (n) is increased from one to four (which results in shorter blocks). Set II consists of materials in which the block lengths are held constant and n is varied again from one to four (which results in longer chains). Transmission electron microscopy (TEM) has been employed here to investigate the morphologies and phase behavior of these materials and their blends.

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