Physics Commons^™

Changing Mutual Perception Of Television News Viewers And Program Makers In India- A Case Study Of Cnn-Ibn And Its Unique Initiative Of Citizen Journalism, Ratnesh Dwivedi Mr

Ratnesh Dwivedi

The Indian television system is one of the most extensive systems in the world. Terrestrial broadcasting, which has been the sole preserve of the government, provides television coverage to over 90% of India's 900 million people. By the end of 1996 nearly 50 million households had television sets. International satellite broadcasting, introduced in 1991, has swept across the country because of the rapid proliferation of small scale cable systems. By the end of 1996, Indians could view dozens of foreign and local channels and the competition for audiences and advertising revenues was one of the hottest in the world. In …

Source Attribution Of Ozone In Southeast Texas Before And After The Deepwater Horizon Accident Using Satellite, Sonde, Surface Monitor, And Air Mass Trajectory Data, Gary A. Morris, Barry Lefer, Bernhard Rappenglueck, Christine Haman, Marc Taylor, Mark R. Schoeberl

Gary A. Morris

Since the summer of 2004, over 300 ozonesondes have been launched from Rice University (29.7 N, 95.4 W) or the University of Houston (29.7 N, 95.3 W), each < 5 km from downtown Houston. The Texas Commission on Environmental Quality maintains a large database of hourly surface ozone observations in Southeast Texas. In this study, we identify the contributions to surface ozone pollution levels from natural and anthropogenic sources, both local and remote in nature. This source identification is performed two ways: 1) through an analysis of sonde data, including ozone concentrations, wind speed and direction, and relative humidity data, and 2) through an analysis that combines trajectory calculations with surface monitor data. We also examine regional changes in Ozone Monitoring Instrument (OMI) measurements of formaldehyde and ozone from 2004 – 2010. In particular, we compare the 2010 sonde, surface monitor, and satellite data after the Deepwater Horizon accident with data from previous years to determine the impact, if any, of the large source of hydrocarbons in the Gulf of Mexico on air quality in Southeast Texas.

All-Optical Control Of Nonlinear Self-Focusing In Plasmas Using Non-Resonantly Driven Plasma Wave, Serguei Y. Kalmykov, Bradley A. Shadwick, Michael C. Downer

Serge Youri Kalmykov

Excitation of plasma density perturbations by an initially bi-color laser pulse helps to control nonlinear refraction in the plasma and enables various types of laser self-guiding. In this report we consider a setup that not only makes possible the transport of laser energy over cm-long relatively dense plasmas (n_0 = 10^{18} cm^{−3}) but also transforms the pulse into the unique format inaccessible to the conventional amplification techniques (relativistically intense periodic trains of few-cycle spikes). This well focusable pulse train is a novel light source interesting for ultra-fast high-field science applications. The opposite case of suppression of nonlinear self-focusing and dynamical …

Electron Self-Injection Into An Evolving Plasma Bubble: The Way To A Dark Current Free Gev-Scale Laser Accelerator, Serguei Y. Kalmykov, Arnaud Beck, Sunghwan A. Yi, Vladimir N. Khudik, Bradley A. Shadwick, Erik Lefebvre, Michael C. Downer

Serge Youri Kalmykov

A time-varying electron density bubble created by the radiation pressure of a tightly focused petawatt laser pulse traps electrons of ambient rarefied plasma and accelerates them to a GeV energy over a few-cm distance. Expansion of the bubble caused by the shape variation of the self-guided pulse is the primary cause of electron self-injection in strongly rarefied plasmas (n_0 ~ 10^{17} cm^{−3}). Stabilization and contraction of the bubble extinguishes the injection. After the bubble stabilization, longitudinal non-uniformity of the accelerating gradient results in a rapid phase space rotation that produces a quasi-monoenergetic bunch well before the de-phasing limit. Combination of …

Determination Of The Axial-Vector Weak Coupling Constant With Ultracold Neutrons., J. Liu, Michael P. Mendenhall, Anthony T. Holley, Henning O. Back, Thomas J. Bowles, Leah J. Broussard, Richard Carr, Stephen Clayton, Scott Currie, Bradley W. Filippone, A. Garcı́A, Peter Geltenbort, Kevin P. Hickerson, J. Todd Hoagland, Gary E. Hogan, B. Hona, Takeyasu M. Ito, Chenyu Liu, Mark Makela, Russell R. Mammei, J.W. Martin, Daneil Melconian, Charles L. Morris, Robert W. Pattie, A. Pérez Galván, Margaret L. Pitt, Bradley Plaster, John C. Ramsey, R. Rios, R. Russell, Andy Saunders, Susan J. Seestrom, Walter E. Sondheim, E. Tatar, Robert B. Vogelaar, Brittany Vorndick, Christopher Wrede, H. Yan, Albert R. Young

Robert W. Pattie Jr.

Community Radio:History,Growth,Challenges And Current Status Of It With Special Reference To India, Ratnesh Dwivedi Mr

Ratnesh Dwivedi

Community radio is a type of radio service that caters to the interests of a certain area, broadcasting content that is popular to a local audience but which may often be overlooked by commercial or mass-media broadcasters. Modern-day community radio stations often serve their listeners by offering a variety of content that is not necessarily provided by the larger commercial radio stations. Community radio outlets may carry news and information programming geared toward the local area, particularly immigrant or minority groups that are poorly served by other major media outlets. Philosophically two distinct approaches to community radio can be discerned, …

Unidirectional Nonlinear Pt-Symmetric Optical Structures, Hamidreza Ramezani, Tsampikos Kottos, Ramy El-Ganainy, Demetrios N. Christodoulides

Ramy El-Ganainy

We show that nonlinear optical structures involving a balanced gain-loss profile can act as unidirectional optical valves. This is made possible by exploiting the interplay between the fundamental symmetries of parity (P) and time (T), with optical nonlinear effects. This unidirectional dynamics is specifically demonstrated for the case of an integrable PT -symmetric nonlinear system.

History Of Communication And Its Application In Multicultaral,Multilingual Social System In India Across Ages, Ratnesh Dwivedi Mr

Ratnesh Dwivedi

The history of communication dates back to the earliest signs of cavemen.Communication can range from very subtle processes of exchange, to full conversations and mass communication. Human communication was revolutionized with speech perhaps 200,000 years ago, Symbols were developed about 30,000 years ago and writing about 7,000. On a much shorter scale, there have been major developments in the field of telecommunication in the past few centuries.

Short-Range Smectic Order In Bent-Core Nematic Liquid Crystals, S. H. Hong, R. Verduzco, J. C. Williams, R. J. Twieg, E. Dimasi, R. Pindak, Antal Jakli, J. T. Gleeson, Samuel Sprunt

Antal Jakli

Small angle X-ray diffraction from the uniaxial nematic phase of certain bent-core liquid crystals is shown to be consistent with the presence of molecular clusters possessing short-range tilted smectic (smectic-C) order. Persistence of these clusters throughout the nematic phase, and even into the isotropic state, likely accounts for the unusual macroscopic behavior previously reported in bent-core nematics, including an anomalously large flexoelectric effect (similar to 1000 times that of conventional calamitic nematics), very large orientational and flow viscosities (similar to 10 100 and similar to 100 1000 times, respectively, typical values for calamitics), and an extraordinary flow birefringence observed in …

Absolute Ground-State Nitrogen Atom Density In A N2/Ch4 Late Afterglow: Talif Experiments And Modelling Studies, Et. Es-Sebbar, M.-C. Gazeau, Y. Benilan, A. Jolly, C D. Pintassilgo

Dr. Et-touhami Es-sebbar

Following a first study on a late afterglow in flowing pure nitrogen post discharge, we report new two-photon absorption laser-induced fluorescence (TALIF) measurements of the absolute ground-state atomic nitrogen density N(4S) and investigate the influence of methane introduced downstream from the discharge by varying the CH4 mixing ratio from 0% up to 50%. The N (4S) maximum density is about 2.2 × 1015 cm−3 in pure N2 for a residence time of 22 ms and does not change significantly for methane mixing ratio up to ~15%, while above, a drastic decrease is observed. The influence of the residence time has …

Hydration Dynamics At Fluorinated Protein Surfaces, Oh-Hoon Kwon, Tae Hyeon Yoo, Christina M. Othon, James A. Van Deventer, David A. Tirrell, Ahmed H. Zewail

Christina M Othon

Water-protein interactions dictate many processes crucial to protein function including folding, dynamics, interactions with other biomolecules, and enzymatic catalysis. Here we examine the effect of surface fluorination on water-protein interactions. Modification of designed coiled-coil proteins by incorporation of 5,5,5-trifluoroleucine or (4S)-2-amino-4-methylhexanoic acid enables systematic examination of the effects of side-chain volume and fluorination on solvation dynamics. Using ultrafast fluorescence spectroscopy, we find that fluorinated side chains exert electrostatic drag on neighboring water molecules, slowing water motion at the protein surface.

Effect Of Particle Properties And Light Polarization On The Plasmonic Resonances In Metallic Nanoparticles, U. Guler, R. Turan

U. Guler

The resonance behavior of localized surface plasmons in silver and gold nanoparticles was studied in the visible and near-infrared regions of the electromagnetic spectrum. Arrays of nano-sized gold (Au) and silver (Ag) particles with different properties were produced with electron-beam lithography technique over glass substrates. The effect of the particle size, shape variations, period, thickness, metal type, substrate type and sulfidation were studied via transmission and reflectance measurements. The results are compared with the theoretical calculations based on the DDA simulations performed by software developed in this study. We propose a new intensity modulation technique based on localized surface plasmons …

Multirelational Organization Of Large-Scale Social Networks In An Online World, Renaud Lambiotte

Renaud Lambiotte

The capacity to collect fingerprints of individuals in online media has revolutionized the way researchers explore human society. Social systems can be seen as a nonlinear superposition of a multitude of complex social networks, where nodes represent individuals and links capture a variety of different social relations. Much emphasis has been put on the network topology of social interactions, however, the multidimensional nature of these interactions has largely been ignored, mostly because of lack of data. Here, for the first time, we analyze a complete, multirelational, large social network of a society consisting of the 300,000 odd players of a …

Experimental And Theoretical Studies On Nitrogen Plasma And Methane Photolysis: Implications For Laboratory Simulations Of Titan’S Atmosphere, M-C. Gazeau, Y. Benilan, E. Arzoumanian, Et. Es-Sebbar, A. Jolly

Dr. Et-touhami Es-sebbar

No abstract provided.

Spectroscopic Studies Applied To Uvis Observations Of Titan, Y. Benilan, F. Capalbo, Et. Es-Sebbar, N. Fray, A. Jolly, M-C. Gazeau, J-C. Guillemin, M. Schwell

Dr. Et-touhami Es-sebbar

No abstract provided.

Talif Investigation And Modelling Of The Absolute N(4s) Density In A N2-Ch4 Late Afterglow, C.D. Pintassilgo, Et. Es-Sebbar, Y. Benilan, M-C. Gazeau, A. Jolly

Dr. Et-touhami Es-sebbar

The purpose of the present work is the experimental and numerical study of the absolute ground-state nitrogen atoms density N(4S) in the late afterglow of a pure N2 flowing microwave discharge in which different amounts of CH4 have been injected at 25 cm downstream from the nitrogen discharge. The absolute N(4S) concentrations have been measured using Two-photon Absorption Laser-Induced Fluorescence (TALIF), while a detailed kinetic model has been developed to simulate both the discharge and the post-discharge regions. Theoretical predictions are then compared to experimental measurements.

Combined Experimental And Theoretical Studies On Methane Photolysis At 121.6 Nm And 248 Nm- Implications On A Program Of Laboratory Simulations Of Titan’S Atmosphere, C. Romanzin, E. Arzoumanian, Et. Es-Sebbar, A. Jolly, S. Perrier, M.-C. Gazeau, Y. Bénilan

Dr. Et-touhami Es-sebbar

Methane is, together with N2, the main precursor of Titan’s atmospheric chemistry. In our laboratory, we are currently developing a program of laboratory simulations of Titan’s atmosphere, where methane is intended to be dissociated by multiphotonic photolysis at 248 nm. A preliminary study has shown that multiphotonic absorption of methane at 248 nm is efficient and leads to the production of hydrocarbons such as C2H2 (Romanzin et al., 2008). Yet, at this wavelength, little is known about the branching ratios of the hydrocarbon radicals (CH3, CH2 and CH) and their following photochemistry. This paper thus aims at investigating methane photochemistry …

Algebraic Characteristics And Satisfiability Threshold Of Random Boolean Equations, Binghui Guo Dr, Wei Wei Dr, Yifan Sun Dr, Zhiming Zheng Dr

Yifan Sun

No abstract provided.

Application Of Asymptotic Expansions For Maximum Likelihood Estimators Errors To Gravitational Waves From Binary Mergers: The Single Interferometer Case, M. Zanolin, S. Vitale, N. Makris

Michele Zanolin

Temperature-Dependent Photoabsorption Cross-Section Of Cyano-Diacetylene In The Vacuum Uv, N. Fray, Y. Bénilan, M.-C. Gazeau, A. Jolly, M. Schwell, E. Arzoumanian, Et. Es-Sebbar, T. Ferradaz, J.- C. Guillemin

Dr. Et-touhami Es-sebbar

Using synchrotron radiation as a tunable VUV light source, we have measured, for the first time, the absolute photoabsorption cross sections of HC5N with a spectral resolution of 0.05 nm in the region between 80 and 205 nm from 233 to 298 K. The measured cross sections are used to predict the HC5N photodestruction rate in the solar system and to model a transmission spectrum in Titan's atmosphere. Comparing the latter with that acquired by the Ultraviolet Imaging Spectrograph on board the Cassini spacecraft, we have determined an upper limit of 2.7 × 10−5 on the HC5N abundance at 1100 …

Pt-Symmetric Optical Lattices, Konstantinos G. Makris, Ramy El-Ganainy, Demetrios N. Christodoulides, Z. H. Musslimani

Ramy El-Ganainy

The basic properties of Floquet-Bloch (FB) modes in parity-time (PT )-symmetric optical lattices are examined in detail. Due to the parity-time symmetry of such complex periodic potentials, the corresponding FB modes are skewed (nonorthogonal) and nonreciprocal. The conjugate pairs of these FB modes are obtained by reflecting both the spatial coordinate and the Bloch momentum number itself. The orthogonality conditions are analytically derived for a single cell, for both a finite and an infinite lattice. Some of the peculiarities associated with the diffraction dynamics in PT lattices such as nonreciprocity, power oscillations, and phase dislocations, are also examined.

A Tutorial On The Basic Physics Of Climate Change, David W. Hafemeister, Peter V. Schwartz

Peter V. Schwartz

In this paper, we have used several basic atmospheric–physics models to show that additional carbon dioxide will warm the surface of Earth. We also show that observed solar variations cannot account for observed global temperature increase.

Light-Induced Self-Synchronizing Flow Patterns, Elad Greenfield, Carmel Rotschild, Alexander Szameit, Jonathan Nemirovsky, Ramy El-Ganainy, Demetrios N. Christodoulides, Meirav Saraf, Efrat Lifshitz, Mordechai Segev

Ramy El-Ganainy

In this paper, we present the observation of light-induced self-synchronizing flow patterns in a light–fluid system. A light beam induces local flow patterns in a fluid, which oscillate periodically or chaotically in time. The oscillations within different regions of the fluid interact with each other through heat- and surface-tension-induced fluid waves, and they become synchronized. We demonstrate optical control over the state of synchronization and over the temporal correlation between different parts of the flow field. Finally, we provide a model to elucidate these results and we suggest further ideas on light controlling flow and vice versa.

Co And H3 + Toward Mwc 1080, Mwc 349, And Lkhα 101, Erika Gibb, S. D. Brittain, T W. Rettig, M Troutman, Theodore Simon, C Kulesa

Erika Gibb

Numerical Modelling Of A 10-Cm-Long Multi-Gev Laser Wakefield Accelerator Driven By A Self-Guided Petawatt Pulse, Serguei Y. Kalmykov, Sunghwan A. Yi, Arnaud Beck, Agustin F. Lifschitz, Xavier Davoine, Erik Lefebvre, Alexander Pukhov, Vladimir N. Khudik, Gennady Shvets, Steven A. Reed, Peng Dong, Xiaoming Wang, Dongsu Du, Stefan Bedacht, Rafal B. Zgadzaj, Watson Henderson, Aaron Bernstein, Gilliss Dyer, Mikael Martinez, Erhard Gaul, Todd Ditmire, Michael C. Downer

Serge Youri Kalmykov

Holographic Visualization Of Laser Wakefields, Peng Dong, Steven A. Reed, Sunghwan A. Yi, Serguei Y. Kalmykov, Zhengyan Y. Li, Gennady Shvets, Nicholas H. Matlis, Christopher Mcguffey, Stepan S. Bulanov, Vladimir Chvykov, Galina Kalintchenko, Karl Krushelnick, Anatoly Maksimchuk, Takeshi Matsuoka, Alexander G. R. Thomas, Victor Yanovsky, Michael C. Downer

Serge Youri Kalmykov

We report ‘snapshots’ of laser-generated plasma accelerator structures acquired by frequency domain holography (FDH) and frequency domain shadowgraphy (FDS), techniques for visualizing quasi-static objects propagating near the speed of light. FDH captures images of sinusoidal wakes in mm-length plasmas of density 1 < n_{e} < 5 x 10^{18} cm^{−3} from phase modulations they imprint on co-propagating probe pulses. Changes in the wake structure (such as the curvature of the wavefront), caused by the laser and plasma parameter variations from shot to shot, were observed. FDS visualizes lasergenerated electron density bubbles in mm-length plasmas of density n_{e} > 10^{19} cm^{−3} using amplitude modulations they imprint on co-propagating probe pulses. Variations in the spatio-temporal structure of bubbles are inferred from corresponding variations in the shape of ‘bullets’ of probe light trapped inside them and correlated with mono-energetic electron generation. Both FDH and FDS average over structural variations that occur during propagation through the plasma medium. We explore …

Formation Of Optical Bullets In Laser-Driven Plasma Bubble Accelerators, Peng Dong, Steven A. Reed, Sunghwan A. Yi, Serguei Y. Kalmykov, Gennady Shvets, Michael C. Downer, Nicholas H. Matlis, Wim P. Leemans, Christopher Mcguffey, Stepan S. Bulanov, Vladimir Chvykov, Galina Kalintchenko, Karl Krushelnick, Anatoly Maksimchuk, Takeshi Matsuoka, Alexander G. R. Thomas, Victor Yanovsky

Serge Youri Kalmykov

Electron density bubbles—wake structures generated in plasma of density n_{e} ~ 10^{19} cm^{-3} by the light pressure of intense ultrashort laser pulses—are shown to reshape weak copropagating probe pulses into optical ‘‘bullets.’’ The bullets are reconstructed using frequency-domain interferometric techniques in order to visualize bubble formation. Bullets are confined in three dimensions to plasma-wavelength size, and exhibit higher intensity, broader spectrum and flatter temporal phase than surrounding probe light, evidence of their compression by the bubble. Bullets observed at 0.8 < n_{e} < 1.2 x 10^{19} cm^{-3} provide the first observation of bubble formation below the electron capture threshold. At higher n_{e}, bullets appear with high shot-to-shot stability together with relativistic electrons that vary widely in spectrum, and help relate bubble formation to fast electron generation.

Electrically Switched Color With Polymer-Stabilized Blue-Phase Liquid Crystals, Shin-Ying Lu, Liang-Chy Chien

Liang-Chy Chien

We report an electrical-field switched color device using a polymer-stabilized blue-phase ( PSBP) liquid crystal in which the Bragg-reflected color of the blue phase ( BP) can be switched to reflect a second color. The phase-separated three-dimensional polymer network transcribes the cubic structure of a BP liquid crystal and restrains the deformation of cubic lattice by the external electric field. The new wide-range electric-field switched colors with PSBP may be an important step toward ecofriendly color reflective displays. (C) 2010 Optical Society of America

Dynamics Of A Liquid-Crystal Variable Optical Prism Based On Pancharatnam Phase, Lei Shi, Paul F. Mcmanamon, Douglas Bryant, Ke Zhang, Philip J. Bos

Philip J. Bos

We consider the dynamics of a variable optical prism based on Pancharatnam phase. The device basics, using liquid crystals (LCs) as the electro-optical material, have been previously proposed. In this paper, we study the dynamics of discrete changes in the phase profile, and also continuous changes in the phase profile through acquired data and numerical modeling. We show that a design based on LCs whose dielectric anisotropy can change sign (as a function of frequency) allows continuous tuning with reasonable response times.

Design Considerations For High Efficiency Liquid Crystal Decentered Microlens Arrays For Steering Light, Lei Shi, Jianru Shi, Paul F. Mcmanamon, Philip J. Bos

Philip J. Bos

We have investigated the causes of low efficiency for optical beam steering devices based on liquid crystal decentered microlens arrays (DLAs). We show that the efficiency is effected by the relative phase of light exiting the individual lenses, the imperfect focusing of small lenses due to diffraction, the aberrations related to off-axis light going through a lens, and the diffraction spreading of light beams going through the DLA structure. A high steering efficiency of over 94.4% is demonstrated by modeling the transmitted light through the DLA with scalar diffraction theory. We also propose modified phase profiles for the lenses that …