2,337 research outputs found
Non-homogeneous random walks, subdiffusive migration of cells and anomalous chemotaxis
This paper is concerned with a non-homogeneous in space and non-local in time
random walk model for anomalous subdiffusive transport of cells. Starting with
a Markov model involving a structured probability density function, we derive
the non-local in time master equation and fractional equation for the
probability of cell position. We show the structural instability of fractional
subdiffusive equation with respect to the partial variations of anomalous
exponent. We find the criteria under which the anomalous aggregation of cells
takes place in the semi-infinite domain.Comment: 18 pages, accepted for publicatio
Metamaterial with polarization and direction insensitive resonant transmission response mimicking electromagnetically induced transparency
We report on a planar metamaterial, the resonant transmission frequency of which does not depend on the polarization and angle of incidence of electromagnetic waves. The resonance results from the excitation of high-Q antisymmetric trapped current mode and shows sharp phase dispersion characteristic to Fano-type resonances of the electromagnetically induced transparency phenomenon
Metamaterials: optical activity without chirality
We report that the classical phenomenon of optical activity, which is traditionally associated with chirality (helicity) of organic molecules, proteins, and inorganic structures, can be observed in artificial planar media which exhibit neither 3D nor 2D chirality. We observe the effect in the microwave and optical parts of the spectrum at oblique incidence to regular arrays of nonchiral subwavelength metamolecules in the form of strong circular dichroism and birefringence indistinguishable from those of chiral three-dimensional media
Beam test results of 3D fine-grained scintillator detector prototype for a T2K ND280 neutrino active target
An upgrade of the long baseline neutrino experiment T2K near detector ND280
is currently being developed with the goal to reduce systematic uncertainties
in the prediction of number of events at the far detector Super-Kamiokande. The
upgrade program includes the design and construction of a new highly granular
fully active scintillator detector with 3D WLS fiber readout as a neutrino
target. The detector of about in size and a mass
of 2.2~tons will be assembled from about plastic
scintillator cubes of . Each cube is read out by three
orthogonal Kuraray Y11 Wave Length Shifting (WLS) fibers threaded through the
detector. A detector prototype made of 125 cubes was assembled and tested in a
charged particle test beam at CERN in the fall of 2017. This paper presents the
results obtained on the light yield and timing as well as on the optical
cross-talk between the cubes.Comment: 5 pages, 8 figure
A toy model of fractal glioma development under RF electric field treatment
A toy model for glioma treatment by a radio frequency electric field is
suggested. This low-intensity, intermediate-frequency alternating electric
field is known as the tumor-treating-field (TTF). In the framework of this
model the efficiency of this TTF is estimated, and the interplay between the
TTF and the migration-proliferation dichotomy of cancer cells is considered.
The model is based on a modification of a comb model for cancer cells, where
the migration-proliferation dichotomy becomes naturally apparent. Considering
glioma cancer as a fractal dielectric composite of cancer cells and normal
tissue cells, a new effective mechanism of glioma treatment is suggested in the
form of a giant enhancement of the TTF. This leads to the irreversible
electroporation that may be an effective non-invasive method of treating brain
cancer.Comment: Submitted for publication in European Physical Journal
Consistent alpha-cluster description of the 12C (0^+_2) resonance
The near-threshold 12C (0^+_2) resonance provides unique possibility for fast
helium burning in stars, as predicted by Hoyle to explain the observed
abundance of elements in the Universe. Properties of this resonance are
calculated within the framework of the alpha-cluster model whose two-body and
three-body effective potentials are tuned to describe the alpha - alpha
scattering data, the energies of the 0^+_1 and 0^+_2 states, and the
0^+_1-state root-mean-square radius. The extremely small width of the 0^+_2
state, the 0_2^+ to 0_1^+ monopole transition matrix element, and transition
radius are found in remarkable agreement with the experimental data. The
0^+_2-state structure is described as a system of three alpha-particles
oscillating between the ground-state-like configuration and the elongated chain
configuration whose probability exceeds 0.9
Application of bent crystals at IHEP 70-GeV accelerator to enhance the efficiency of its usage
Bent crystal was extracting 70-GeV protons with average intensity 4*10^11 (as
measured in external beamline) per spill of 1.6 s duration, in parallel to the
simultaneous work of two internal targets in the accelerator ring. An
additional crystal, placed in the external beamline, was deflecting a small
part of the extracted beam with intensity 10^7 protons toward another physics
experiment. Crystal-extracted beam had a typical size of 4 mm by 4 mm fwhm at
the end of the external beamline. Measurements for the extraction efficiency
and other characteristics at the simultaneous work of four experimental set-ups
are presented. With crystal working in the above-said regime during one month,
no degradation of channeling was observed. The studies of extraction efficiency
have been continued with new crystals.Comment: 6pp. Presented at EPAC 200
Evaluating transport in irregular pore networks
A general approach for investigating transport phenomena in porous media is presented. This approach has the capacity to represent various kinds of irregularity in porous media without the need for excessive detail or computational effort. The overall method combines a generalized effective medium approximation (EMA) with a macroscopic continuum model in order to derive a transport equation with explicit analytical expressions for the transport coefficients. The proposed form of the EMA is an anisotropic and heterogeneous extension of Kirkpatrick's EMA which allows the overall model to account for microscopic alterations in connectivity (with the locations of the pores and the orientation and length of the throat) as well as macroscopic variations in transport properties. A comparison to numerical results for randomly generated networks with different properties is given, indicating the potential for this methodology to handle cases that would pose significant difficulties to many other analytical models
The Investigations Of Beam Extraction And Collimation At U-70 Proton Synchrotron Of IHEP By Using Short Silicon Crystals
The new results of using short (2-4mm) bent crystals for extraction and
collimation of proton beam at IHEP 70 Gev proton synchrotron are reported. A
broad range of energies from 6 to 65 GeV has been studied in the same crystal
collimation set-up. The efficiency of extraction more than 85% and intensity
more than 10E12 were obtained by using crystal with the length 2-mm and the
angle 1 mrad. The new regime of extraction is applied now at the accelerator to
deliver the beam for different experimental setups within the range of
intensity 10E7-10E12ppp.Comment: Presented at EPAC 2002 (Paris, June 3-7), 3p
- …