776 research outputs found
DC-assisted microwave quenching of YBa2Cu3O7-{\delta} coplanar waveguide to a highly dissipative state
The paper reports on finding the effect of a strong change in the microwave
losses in an HTS-based coplanar waveguide (CPW) at certain values of the input
power Pin and direct current Idc. CPW on the basis of 150 nm thick
YBa2Cu3O7-{\delta} epitaxial film on a single crystal MgO substrate was studied
experimentally. A sharp and reversible transition of the CPW into a strongly
dissipative state at the certain meanings of Pin and Idc depending on
temperature was observed. Apparently the effect can be explained by
self-heating of HTS structure caused by magnetic flux flow under the joint
influence of MW and DC.Comment: 9 pages, 5 figures, 17 reference
Aneurysm of a paraumbilical collateral vein.
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135619/1/jum1988711639.pd
HuR overexpression in MB231 breast cancer cells
Abstract only availableCancer cells share acquired capabilities necessary for their malignant transformation. These "hallmarks of cancer" include increased proliferation, self-sufficiency in growth signals, insensitivity to antigrowth signals, evasion of apoptosis, angiogenesis and metastasis (Hanahan and Weinberg 2000). HuR is a RNA-binding protein which has been implicated in regulating mRNAs involved in each of these characteristics. We hypothesize that HuR maintains the growth characteristics of malignant cancer cells through the stabilization and increased translation of cancer relevant genes. If HuR does enhance malignancy then the overexpression of HuR would amplify the capabilites of malignant cancer cells and increase cell proliferation. This hypothesis was tested by creating a breast cancer cell line that stably overexpresses HuR. A vector overexpressing HuR was created by ligating a PCR amplified insert containing HuR and a HA hemagluttin tag into a Zeocin resistant episomal plasmid. Cells normally express HuR, so the tag was used to distinguish the overexpressed HuR from endogenous HuR. This plasmid was used to transfect MB-231 estrogen receptor-negative breast cancer cells. After transfection, Zeocin selected against the cells that did not incorporate the plasmid. Western Blots for the surviving cells revealed that HA HuR was expressed, implying that the cells were overexpressing HuR. Proliferation assays of heterogenous populations of both HA HuR-containing and normal MB231 cells yield no difference in cell division. Further experiments will use homogenous populations that highly overexpress HuR to see if HuR overexpression alters the proliferation and cell cycle capabilities of these cells. References: "Hallmarks of Cancer" Hanahan, Douglas and Weinberg, Robert A. Cell. Vol. 100, 57-70. 200
The Features of Surface Plasmon-Polariton Pulses Generation Via Cooperative Effects in Waveguide Spaser
The problem of sub-picosecond plasmon-polariton pulse formation in metal/dielectric interface due to collective decay of excited quantum dots, placed in the dielectric layer near the metal surface, is considered. Theoretical approach to selection of semiconductor quantum dots and dielectric host medium to increase the energy transmission of quantum dot collective excitations into surface plasmon-polariton modes of waveguide spaser is developed
Quantum chaos: an introduction via chains of interacting spins-1/2
We introduce aspects of quantum chaos by analyzing the eigenvalues and the
eigenstates of quantum many-body systems. The properties of quantum systems
whose classical counterparts are chaotic differ from those whose classical
counterparts are not chaotic. The spectrum of the first exhibits repulsion of
the energy levels. This is one of the main signatures of quantum chaos. We show
how level repulsion develops in one-dimensional systems of interacting spins
1/2 which are devoid of random elements and involve only two-body interactions.
In addition to the statistics of the eigenvalues, we analyze how the structure
of the eigenstates may indicate chaos. The programs used to obtain the data are
available online.Comment: 7 pages, 3 figure
Noise-induced topological transformations of vortex solitons in optical fibers filled with a cold atomic gas
We consider the influence of optical and temperature-dependent atomic
fluctuations on the formation and propagation of optical vortex solitons in
dense media realized as hollow-core optical fibers filled with a cold atomic
gas in presence of optical pumping. We show different perturbation-induced
scenaria of complete destruction and smooth transformations of the topological
characteristics of localized optical structures in hollow-core fiber. The
maximum levels of optical and atomic fluctuations at which the soliton regime
can be maintained has been determined. The estimates for these levels show an
opportunity to observe the optical vortex solitions in the core-filling gas of
the fiber for temperatures smaller than the critical temperature for
Bose-Einstein condensate.Comment: 12 pages, 10 EPS figures, submitted to Physical Review
Multiresonances of quasi-trapped modes in metasurfaces based on nanoparticles of transition metal dichalcogenides
The features of polarization control of multiple multiresonances for
quasi-trapped modes excited by synchronization of bianisotropic dipole
responses in MoS disks with a hole are considered. Using the numerical
calculations with analytical multipole analysis, we showed that the presence of
a strong optical anisotropy of MoS nanoparticles provides an additional
degree of freedom and allows to observe several resonances of electric and
magnetic dipoles at once in a narrow spectral range. Based on the simulation
results, we obtained the frequency dependences for the dipole polarizabilities
of the MoS disk with a hole, which allow one to distinguish the
contributions of the nonlocal and bianisotropic dipole responses and possessing
several features in the near infrared range. Using the polarizability spectra
of single nanoparticles and applying the tuning strategy, the design of the
MoS metasurface supporting three resonances of quasi-trapped modes at once
in a narrow spectral range was developed. One of these resonances corresponds
to the telecom wavelength of 1550 nm. The spectrum of light reflection for
MoS metasurface is characterized by three narrowband dips corresponding to
the wavelengths of the quasi-trapped modes. It was shown that a change in the
polarization of a wave normally incident on the metasurface to orthogonal one
leads to a change in the type of bianisotropic response excited in each MoS
disk and to the excitation of three other features in the reflection spectra of
the metasurface at wavelengths close to the initial values.Comment: 8 pages, 5 figure
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