K. Papadopoulos

Aristotle University of Thessaloniki

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G. M. Milikh

University of Maryland, College Park

A. S. Sharma

University of Maryland, College Park

C. C. Goodrich

University of Maryland, College Park

B. Eliasson

University of Strathclyde

X. Shao

Jinhua Academy of Agricultural Sciences

Xi Shao

University of Maryland, College Park

P. J. Palmadesso

United States Naval Research Laboratory

Walter Gekelman

University of California, Los Angeles

J. G. Lyon

Dartmouth College

M. Wiltberger

High Altitude Observatory

Cooperative Institutions

University of Maryland, College Park

124

United States Naval Research Laboratory

University of California, Los Angeles

Goddard Space Flight Center

Naval Research Laboratory Plasma Physics Division

Aristotle University of Thessaloniki

Tulane University

Science Applications International Corporation (United States)

System Science Applications (United States)

Johns Hopkins University Applied Physics Laboratory

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Spontaneous Magnetic Fields in Laser-Produced Plasmas

Physical Review Letters (1971)

J. A. Stamper K. Papadopoulos R. N. Sudan Stephen O. Dean E. A. McLean

Spontaneously generated magnetic fields of the order of a kilogauss have been observed in a laser-produced plasma, using a variety of targets and background pressures. The generation of these magnetic fields is explained in terms of thermoelectric currents associated with large temperature gradients near the target.

10.1103/physrevlett.26.1012

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Citations (528)

Reply [to “Comment on ‘Generation of electron plasma waves in the upstream solar wind’ By S. F. Fung, K. Papadopoulos, and C. S. Wu”]

Journal of Geophysical Research Atmospheres (1983)

Shing F. Fung K. Papadopoulos Chao Wu

10.1029/ja088ia09p07255

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Citations (1)

Tunable, bandwidth controllable source of THz radiation

IEE Proceedings - Optoelectronics (2002)

A. Zigler D. Hashimshony K. Papadopoulos

Tunable radiation in the range from 0.1 to a few THz by the interaction of a superluminous photoconducting front with an electrostatic ‘frozen wave’ configuration in a semiconductor is reported. The interaction converts the energy contained in the ‘frozen wave’ into THz radiation, whose frequency depends on the energy in the laser pulse creating the superluminous front and the wavelength of the static wave. Use of two-photon absorption leads to a volume interaction, creating a superluminous photoconducting front. Tunability was achieved by varying the laser pulse energy from 0.1 to 1 mJ. Power scaling as a function of the electrostatic ‘frozen wave’ energy was obtained. The capability of the concept to act as a narrow or wideband, tunable and powerful THz source is demonstrated.

Wideband

10.1049/ip-opt:20020535

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Citations (1)

Modeling substorm dynamics of the magnetosphere: From self-organization and self-organized criticality to nonequilibrium phase transitions

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics (2001)

M. I. Sitnov A. S. Sharma K. Papadopoulos D. Vassiliadis

Earth's magnetosphere during substorms exhibits a number of characteristic features such as the signatures of low effective dimension, hysteresis, and power-law spectra of fluctuations on different scales. The largest substorm phenomena are in reasonable agreement with low-dimensional magnetospheric models and in particular those of inverse bifurcation. However, deviations from the low-dimensional picture are also quite considerable, making the nonequilibrium phase transition more appropriate as a dynamical analog of the substorm activity. On the other hand, the multiscale magnetospheric dynamics cannot be limited to the features of self-organized criticality (SOC), which is based on a class of mathematical analogs of sandpiles. Like real sandpiles, during substorms the magnetosphere demonstrates features, that are distinct from SOC and are closer to those of conventional phase transitions. While the multiscale substorm activity resembles second-order phase transitions, the largest substorm avalanches are shown to reveal the features of first-order nonequilibrium transitions including hysteresis phenomena and a global structure of the type of a temperature-pressure-density diagram. Moreover, this diagram allows one to find a critical exponent, that reflects the multiscale aspect of the substorm activity, different from the power-law frequency and scale spectra of autonomous systems, although quite consistent with second-order phase transitions. In contrast to SOC exponents, this exponent relates input and output parameters of the magnetosphere. Using an analogy to the dynamical Ising model in the mean-field approximation, we show the connection between the data-derived exponent of nonequilibrium transitions in the magnetosphere and the standard critical exponent beta of equilibrium second-order phase transitions.

Substorm

10.1103/physreve.65.016116

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Citations (88)

Mobilization of n-hexadecane in porous media using food grade amphiphiles

Colloids and Surfaces A Physicochemical and Engineering Aspects (2018)

Chike G. Ezeh Chia‐Yu Chen K. Papadopoulos

Hexadecane

Aqueous two-phase system

10.1016/j.colsurfa.2018.08.061

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Citations (7)

Effect of anomalous electron heating on the transpolar potential in the LFM global MHD model

Geophysical Research Letters (2005)

V. G. Merkin G. M. Milikh K. Papadopoulos J. G. Lyon Y. S. Dimant

The tendency of global MHD models to overestimate the transpolar potential in simulations of strong geomagnetic storms and evidence of an adverse feedback of the ionospheric conductance on the potential suggest that these models lack important physics leading to the conductance enhancement. Farley‐Buneman instability in the auroral ionosphere provides this lacking physics. This instability is believed to cause strong anomalous electron heating which affects the ionospheric conductivity. We use an earlier developed model of anomalous electron heating to estimate the ionospheric conductance disturbance as a function of the local electric field. This result is used to modify the ionospheric conductance in the LFM model to study its effect on the simulated transpolar potential. An idealized and a real‐case simulations are accomplished. In both cases a considerable drop in the simulated transpolar potential is found. The latter is in a good agreement with AMIE model and DMSP data.

10.1029/2005gl023315

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Citations (28)

Excitation of the earth‐ionosphere waveguide by an ELF source in the ionosphere

Radio Science (1982)

V. K. Tripathi C. L. Chang K. Papadopoulos

It is shown that for polar regions, where the conductivity is predominantly reactive, the wave functions for the transverse electromagnetic mode of the earth‐ionosphere waveguide are Hankel functions of the first kind with real argument; therefore they extend up to large heights over the polar ionosphere. A Green's function for the excitation of the waveguide by extended current or field sources in the ionosphere is obtained for an exponential ionosphere. The potential of ELF waveguide excitation by wireless antennas is discussed.

Earth–ionosphere waveguide

Waveguide

Schumann resonances

10.1029/rs017i005p01321

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Citations (25)

Breakdown of magnetic insulation in semiconductor plasmas

IEEE Transactions on Plasma Science (1996)

K. Papadopoulos A. Zigler David Book C. M. S. Cohen D. Hashimshony

A theoretical analysis of the current response of strongly magnetized electrically biased photoconductors to short laser pulses, with emphasis on the breakdown of magnetic insulation, is presented. There are two regimes that result in breaking of the magnetic insulation during the "on" time of the pulse: (1) the collisionless regime, applicable to pulses with duration /spl tau//sub 0/<1//spl nu/, where /spl nu/ is the collision frequency, in which the magnetic insulation is broken by a polarization-like current induced by the fast rate of increase of the carriers, and (2) the collisional regime, applicable to pulses with /spl tau//sub 0/>1//spl nu/, where the magnetic insulation is broken at high carrier density due to the nonlinear dependence of the collision frequency on the carrier density. A simple experiment was performed which confirms the physics of the collisional regime. It is shown that the presence of the magnetic field can significantly reduce the response time of photoconductors. Response times shorter than a picosecond can be achieved in the collisionless regime.

Picosecond

Collision frequency

10.1109/27.533117

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Citations (0)

Immunoengineering via Chimeric Antigen Receptor-T Cell Therapy: Reprogramming Nanodrug Delivery

Pharmaceutics (2023)

Theodora Katopodi Savvas Petanidis Doxakis Anestakis Charalampos Charalampidis Ioanna P. Chatziprodromidou

Following its therapeutic effect in hematological metastasis, chimeric antigen receptor (CAR) T cell therapy has gained a great deal of attention during the last years. However, the effectiveness of this treatment has been hampered by a number of challenges, including significant toxicities, difficult access to tumor locations, inadequate therapeutic persistence, and manufacturing problems. Developing novel techniques to produce effective CARs, administer them, and monitor their anti-tumor activity in CAR-T cell treatment is undoubtedly necessary. Exploiting the advantages of nanotechnology may possibly be a useful strategy to increase the efficacy of CAR-T cell treatment. This study outlines the current drawbacks of CAR-T immunotherapy and identifies promising developments and significant benefits of using nanotechnology in order to introduce CAR transgene motifs into primary T cells, promote T cell expansion, enhance T cell trafficking, promote intrinsic T cell activity and rewire the immunosuppressive cellular and vascular microenvironments. Therefore, the development of powerful CART cells can be made possible with genetic and functional alterations supported by nanotechnology. In this review, we discuss the innovative and possible uses of nanotechnology for clinical translation, including the delivery, engineering, execution, and modulation of immune functions to enhance and optimize the anti-tumor efficacy of CAR-T cell treatment.

Reprogramming

Cell therapy

Cancer Immunotherapy

10.3390/pharmaceutics15102458

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Citations (1)

Solar Terrestrial Physics: Present and Future

D. M. Butler K. Papadopoulos

The following topics relating to solar-terrestrial interactions are considered: (1) reconnection of magnetic fields; (2) particle acceleration; (3) solar magnetic flux; (4) magnetohydrodynamic waves and turbulence in the Sun and interplanetary medium; (5) coupling of the solar wind to the magnetosphere; (6) coronal transients; (7) the connection between the magnetosphere and ionosphere; (8) substorms in the magnetosphere; (9) solar flares and the solar terrestrial environment; (10) shock waves in the solar terrestrial environment; (11) plasma transport and convection at high latitudes; and (12) high latitude ionospheric structure.

Nanoflares

Solar flare

Polar wind

Corona (planetary geology)

Magnetosphere of Jupiter

Coronal hole

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Citations (121)