3,852 research outputs found
Effect of dissociation pulse circuit inductance on the CuCl laser
The performance of the double-pulsed CuCI laser is improved by a decrease in the inductance of the dissociation pulse circuit. Higher efficiency is obtained due to a larger ground state copper atom population and lower optimum dissociation energy
Nonlinear Dynamics of Capacitive Charging and Desalination by Porous Electrodes
The rapid and efficient exchange of ions between porous electrodes and
aqueous solutions is important in many applications, such as electrical energy
storage by super-capacitors, water desalination and purification by capacitive
deionization (or desalination), and capacitive extraction of renewable energy
from a salinity difference. Here, we present a unified mean-field theory for
capacitive charging and desalination by ideally polarizable porous electrodes
(without Faradaic reactions or specific adsorption of ions) in the limit of
thin double layers (compared to typical pore dimensions). We illustrate the
theory in the case of a dilute, symmetric, binary electrolyte using the
Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae
are available for salt adsorption and capacitive charging of the diffuse part
of the double layer. We solve the full GCS mean-field theory numerically for
realistic parameters in capacitive deionization, and we derive reduced models
for two limiting regimes with different time scales: (i) In the
"super-capacitor regime" of small voltages and/or early times where the porous
electrode acts like a transmission line, governed by a linear diffusion
equation for the electrostatic potential, scaled to the RC time of a single
pore. (ii) In the "desalination regime" of large voltages and long times, the
porous electrode slowly adsorbs neutral salt, governed by coupled, nonlinear
diffusion equations for the pore-averaged potential and salt concentration
Negative phase time for Scattering at Quantum Wells: A Microwave Analogy Experiment
If a quantum mechanical particle is scattered by a potential well, the wave
function of the particle can propagate with negative phase time. Due to the
analogy of the Schr\"odinger and the Helmholtz equation this phenomenon is
expected to be observable for electromagnetic wave propagation. Experimental
data of electromagnetic wells realized by wave guides filled with different
dielectrics confirm this conjecture now.Comment: 10 pages, 6 figure
Nonlocal reflection by photonic barriers
The time behaviour of microwaves undergoing partial reflection by photonic
barriers was measured in the time and in the frequency domain. It was observed
that unlike the duration of partial reflection by dielectric layers, the
measured reflection duration of barriers is independent of their length. The
experimental results point to a nonlocal behaviour of evanescent modes at least
over a distance of some ten wavelengths. Evanescent modes correspond to
photonic tunnelling in quantum mechanics.Comment: 8 pages, 5 figure
A point mutation in the hair cell nicotinic cholinergic receptor prolongs cochlear inhibition and enhances noise protection
The transduction of sound in the auditory periphery, the cochlea, is inhibited by efferent cholinergic neurons projecting from the brainstem and synapsing directly on mechanosensory hair cells. One fundamental question in auditory neuroscience is what role(s) this feedback plays in our ability to hear. In the present study, we have engineered a genetically modified mouse model in which the magnitude and duration of efferent cholinergic effects are increased, and we assess the consequences of this manipulation on cochlear function. We generated the Chrna9L9âČT of knockin mice with a threonine for leucine change (L9âČT) at position 9âČ of the second transmembrane domain of the α9 nicotinic cholinergic subunit, rendering α9-containing receptors that were hypersensitive to acetylcholine and had slower desensitization kinetics. The Chrna9L9âČT allele produced a 3-fold prolongation of efferent synaptic currents in vitro. In vivo, Chrna9L9âČT mice had baseline elevation of cochlear thresholds and efferent-mediated inhibition of cochlear responses was dramatically enhanced and lengthened: both effects were reversed by strychnine blockade of the α9α10 hair cell nicotinic receptor. Importantly, relative to their wild-type littermates, Chrna9L9âČT/L9âČT mice showed less permanent hearing loss following exposure to intense noise. Thus, a point mutation designed to alter α9α10 receptor gating has provided an animal model in which not only is efferent inhibition more powerful, but also one in which sound-induced hearing loss can be restrained, indicating the ability of efferent feedback to ameliorate sound trauma.Fil: Taranda, Julian. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; Argentina. Tufts University School of Medicine; Estados UnidosFil: Maison, StĂ©phane F.. Massachusetts Eye and Ear Infirmary; Estados UnidosFil: Ballestero, Jimena Andrea. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Katz, Eleonora. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Savino, Jessica. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; ArgentinaFil: Vetter, Douglas E.. Tufts University School of Medicine; Estados UnidosFil: Boulter, Jim. University of California at Los Angeles; Estados UnidosFil: Liberman, M. Charles. Massachusetts Eye and Ear Infirmary; Estados UnidosFil: Fuchs, Paul A.. The Johns Hopkins University School of Medicine; Estados UnidosFil: Elgoyhen, Ana Belen. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Investigaciones en IngenierĂa GenĂ©tica y BiologĂa Molecular "Dr. HĂ©ctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de FarmacologĂa; Argentin
Youth and Adult Education in the Context of Student Movements: The Cases of Egypt, Puerto Rico, and Chile
Participants of the student movements in Egypt, Puerto Rico, and Chile present on their experiential learning in the context of the social movements that took place between 2005 and 2019
Vlasov Description Of Dense Quark Matter
We discuss properties of quark matter at finite baryon densities and zero
temperature in a Vlasov approach. We use a screened interquark Richardson's
potential consistent with the indications of Lattice QCD calculations.
We analyze the choices of the quark masses and the parameters entering the
potential which reproduce the binding energy (B.E.) of infinite nuclear matter.
There is a transition from nuclear to quark matter at densities 5 times above
normal nuclear matter density. The transition could be revealed from the
determination of the position of the shifted meson masses in dense baryonic
matter. A scaling form of the meson masses in dense matter is given.Comment: 15 pages 4 figure
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