Physics Commons^™

Menagerie Of Ads2 Boundary Conditions, Daniel Grumiller, Robert A. Mcnees Iv, Jakob Salzer, Carlos Valcárcel, Dmitri Vassilevich

Physics: Faculty Publications and Other Works

We consider different sets of AdS2 boundary conditions for the Jackiw-Teitelboim model in the linear dilaton sector where the dilaton is allowed to fluctuate to leading order at the boundary of the Poincaré disk. The most general set of boundary conditions is easily motivated in the gauge theoretic formulation as a Poisson sigma model and has an sl(2)" role="presentation" style="box-sizing: inherit; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">𝔰𝔩(2)sl(2) current algebra as asymptotic symmetries. Consistency of the …

Galileo's Contribution To Mechanics, Asim Gangopadhyaya

Physics: Faculty Publications and Other Works

Asim Gangopadhyaya writes about Galileo's contributions to mechanics and physics in this chapter in Where Have All the Heavens Gone? Galileo's Letter to the Grand Duchess Christina edited by John P. McCarthy and Edmondo F. Lupieri.

Can Newton’S Third Law Be “Derived” From The Second?, Asim Gangopadhyaya, James T. Harrington

Physics: Faculty Publications and Other Works

Newton’s laws1 have engendered much discussion over several centuries.2,3 Today, the internet is awash with a plethora of information on this topic. We find many references to Newton’s laws, often discussions of various types of misunderstandings and ways to explain them. Here we present an intriguing example that shows an assumption hidden in Newton’s third law that is often overlooked. As is well known, the first law defines an inertial frame of reference and the second law determines the acceleration of a particle in such a frame due to an external force. The third law describes forces exerted …

Higher-Order Power Harmonics Of Pulsed Electrical Stimulation Modulates Corticospinal Contribution Of Peripheral Nerve Stimulation, Chiun-Fan Chen, Marom Bikson, Li-Wei Chou, Chunlei Shan, Niranjan Khadka, Wen-Shiang Chen, Felipe Fregni

Engineering Science Faculty Publications

It is well established that electrical-stimulation frequency is crucial to determining the scale of induced neuromodulation, particularly when attempting to modulate corticospinal excitability. However, the modulatory effects of stimulation frequency are not only determined by its absolute value but also by other parameters such as power at harmonics. The stimulus pulse shape further influences parameters such as excitation threshold and fiber selectivity. The explicit role of the power in these harmonics in determining the outcome of stimulation has not previously been analyzed. In this study, we adopted an animal model of peripheral electrical stimulation that includes an amplitude-adapted pulse train …

Deformation But Not Migration And Rotation – A Model Study On Vesicle Biomechanics In A Uniform Dc Electric Field, Hui Ye, Austen Curcuru

Biology: Faculty Publications and Other Works

Background: Biological cells migrate, deform and rotate in various types of electric fields, which have significant impact on the normal cellular physiology. To investigate electrically-induced deformation, researchers have used artificial giant vesicles that mimic the phospholipid bilayer cell membrane. Containing primarily the neutral molecule phosphatidylcholine, these vesicles deformed under evenly distributed, strong direct current (DC) electric fields. Interestingly, they did not migrate or rotate. A biophysical mechanism underlying the kinematic differences between the biological cells and the vesicles under electric stimulation has not been worked out.

Methods: We modeled the vesicle as a leaky, dielectric sphere and computed …