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

Energy-efficient adjustable speed double inverter-fed woundrotor induction motor drive

The mathematical and analytical models of adjustable speed electric drive based on double inverter-fed induction motor are considered and analyzed in the article, the main equations which describe energy performances of such type of AC electric drive system are determined. The influence of excitation frequency on energy performances of double inverter-fed induction motor in steady-state at orthogonal flux vector control is considered in the article. The condition ensures minimum of stator steel losses at a predetermined rotor speed and can operate at speeds up to double rated without the magnetic flux reducing is presented. This possibility is one of the most important advantages of this type of electric drive over others types of AC drives for many technological processes.Keywords: power, double-fed wound-rotor induction motor drive, steel and total losses, efficiency, energy-efficient control algorith

Space-Charge and resonance considerations for choosing the SNS ring working points

The beam power of the SNS is an order of magnitude higher than that of existing accelerator facilities. This imposes a strict requirement on the uncontrolled beam loss at a $10^{-4}$ level. The major source of beam loss is associated with machine resonances. Thus, the first step towards reaching low beam loss is to find the best suitable working points on the tune diagram. In this note, we explore the tune space by considering machine resonances and the effect of space charge, which can drive particles into these excited resonances.In addition, space charge itself can induce resonances. Our present studies were driven by these facts and by the fact that previous working points [1] were identified for the shorter ring with 220 m circumference. Also, the combined effects of space charge and magnet errors raised concern for the nominal working point [2-3]

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

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

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 $200\times 180\times 60~cm^3$ in size and a mass of $\sim$2.2~tons will be assembled from about $2\times10^6$ plastic scintillator cubes of $1\times1\times1~cm^3$. 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