Andjelija Ž. Ilić

Hematological parameters' changes in mice subchronically exposed to static magnetic fields of different orientations.

Static magnetic fields (SMFs) are time independent fields whose intensity can be spatially dependent. This study investigates influence of subchronic continuous exposure to upward and downward directed SMF on hematological parameters and spleen cellularity in mice. The experiment is performed on the Northern hemisphere; consequently, the vertical component of geomagnetic field is directed downward. Male, Swiss-Webster, 6 weeks old mice were exposed to the vertically declining SMF. Mice were divided in three groups and continuously exposed or not exposed for 28 days to the SMF characterized by the averaged field of 16 mT and averaged field gradient of 10 mT/cm. Differently oriented SMF did not alter hemoglobin and hematocrit content among the groups. However, the groups exposed to the upward and downward fields had statistically significant higher levels of serum transferrin compared to the control. Moreover, spleen cellularity in animals in the downward group was significantly higher compared to the upward and control group. In addition, spleen lymphocytes in both of the exposed groups were significantly higher than in the control group. In contrast, spleen granulocytes in the exposed groups were significantly lower than in the control group. Significant decrease was also observed in brain and liver iron content with concomitant increase of iron in serum and spleen in exposed animals. Subchronic continuous exposure to 16 mT SMF caused lymphocyte and granulocyte redistribution between spleen and blood. This distribution is typical for stress induced hematological changes. These results suggest that observed changes were not due to an unspecific stress response, but that they were rather caused by specific adaptation to subchronic SMF exposure.

Subchronic exposure to static magnetic field differently affects zinc and copper content in murine organs

Abstract Purpose Static magnetic fields (SMF) have been widely used in research, medicine and industry. Since zinc and copper play an important role in biological systems, we studied the effects of the subchronic continuous SMF exposure on their distribution in murine tissues. Materials and methods For 30 days, mice were exposed to inhomogeneous, vertical, downward or upward oriented SMF of 1 mT averaged intensity with spatial gradient in vertical direction. Results SMF decreased the amount of copper and zinc in liver. In brain, zinc levels were increased and copper levels were decreased. In spleen, zinc content was reduced, while copper amount remained unchanged. Conclusions Subchronic exposure to SMF differently affected copper and zinc content in examined organs, and the changes were more pronounced for the downward oriented field. The outcome could be attributed to the protective, rather than the harmful effect of SMF.

Higher-Order Frequency-Domain FEM Analysis of EM Scattering Off a Moving Dielectric Slab

A higher-order one-dimensional (1-D) finite element method for analysis of electromagnetic wave scattering off of a moving dielectric slab is proposed and developed. The numerical results are verified by comparison to analytical solutions.

Ion Beam Acceleration With Radio Frequency Powered Rainbow Lens

The electrostatic quadrupole lens, quadrupole accelerator and square rainbow lens as well as radio frequency quadrupole accelerator all have similar structure with four rod-like electrodes. Unlike the last one, which is powered by the alternating voltage, the first three are electrostatic devices. Each two adjacent electrodes of a common electrostatic lens have equal magnitude and opposite signs of their electric potentials, whereas, electric potentials of rainbow lenss electrodes are all equal in magnitude as well as in sign. If powered by the appropriate radio frequency instead of a DC voltage, the rainbow lens transforms into an ion beam accelerator which could cost-effectively broaden the available energy range of low energy ion beam facilities.

Role and Significance of Uniform Distribution in a Study of Ensemble of Particles

Dynamics of an ensemble of particles is often studied by tracking a large number of test particles from a chosen initial state to an adequately defined final state. Random distributions of particles over considered parameters are frequently used to describe an initial state of studied ensemble. Randomness of input data insures that there is no overlapping in test particles visualization; however, it hides the dependencies between various input and output parameters. If non-random, uniformly distributed input data is used, relationships between the input and output variables are revealed. Further, mapping of such an input into its output together with an appropriate interpolation scheme contains description of an output corresponding to any desired distribution of input data. A mapping of non-random uniformly distributed input into its output is combined with n -dimensional linear interpolation into a method for studying dynamics of an ensemble of particles. Advantages and efficiency of the method are illustrated using an ion beam interaction with two devices: the four parallel, equally spaced finite wires and the spiral inflector. The method is applicable if interactions between particles within an ensemble are negligible compared to other forces involved.

Constant Speed Parametrization Mapping of Curved Boundary Surfaces in Higher-Order Moment-Method Electromagnetic Modeling

A constant speed parametrization (CSP) mapping of boundary surfaces is proposed for moment-method analysis of antennas and scatterers, along with its approximation using large higher-order Lagrange-type curved quadrilateral patches. The importance of the proper placement of interpolation nodes that ensures minimum mapped parametric space distortion (arc-length parametrization) is explained and demonstrated on simple examples. The CSP mapping results in on average five times lower radar cross section (RCS) error for a spherical scatterer than with the ray casting (central projection) parametrization mapping. The extension of the CSP concept to arbitrary surfaces is illustrated in modeling of the double-ogive target.

Comparison of approximate and full-wave electromagnetic numerical modeling of microstrip matching networks

We consider several planar microstrip circuit elements, often appearing as parts of microwave matching networks, as well as discrete chip components with associated pads. We analyze all considered elements and components using a circuit-based solver and full-wave electromagnetic solvers and compare the analysis results with measurements on manufactured prototypes, discussing the obtained differences and giving specific recipes for good modeling practices using different methods.

Optimization of Equally Charged Quadrupole Parameters

A quadrupole with equally charged electrodes could be used to focus as well as to accelerate ion beams. The equality of electrode charges causes the driving electric field of this device to be qualitatively different from that of other devices with a similar structure composed of four rod-like electrodes. For the same reason, the area of strong field influence on the beam is shifted towards the entrance and exit of the device. Consequently, it is expected that the devices performance depends on the shapes of its entrance and exit regions. The device parameters whose influence is studied are aperture radius, gap size, and rod length. Performance of the device is quantified with accelerating and focusing potentials, which are obtained as integrals of axial and radial electric fields. These variables are further used to choose optimal values of the device parameters for desired operation of the device.

Enhancement of Ion Beam Acceleration Efficiency in Isochronous Cyclotrons

A novel method for efficient analysis of ion beam acceleration in an isochronous cyclotron is proposed. Numerical simulation is used to perform multiple beam dynamics analyses on the conveniently chosen subsets of data; consequently, the total quantity of studied data is significantly reduced. The obtained results provide direct insight into beam behavior and quality of acceleration. Therefore, the analysis is not only efficient, but detailed and systematic as well. It is used to assess the impact of the accelerated orbit optimization to the enhancement of acceleration efficiency when study is extended from a single test ion to the complete ion beam consideration.

Circuit-based versus full-wave modelling of active microwave circuits

ABSTRACT Modern full-wave computational tools enable rigorous simulations of linear parts of complex microwave circuits within minutes, taking into account all physical electromagnetic (EM) phenomena. Non-linear components and other discrete elements of the hybrid microwave circuit are then easily added within the circuit simulator. This combined full-wave and circuit-based analysis is a must in the final stages of the circuit design, although initial designs and optimisations are still faster and more comfortably done completely in the circuit-based environment, which offers real-time solutions at the expense of accuracy. However, due to insufficient information and general lack of specific case studies, practitioners still struggle when choosing an appropriate analysis method, or a component model, because different choices lead to different solutions, often with uncertain accuracy and unexplained discrepancies arising between the simulations and measurements. We here design a reconfigurable power amplifier, as a case study, using both circuit-based solver and a full-wave EM solver. We compare numerical simulations with measurements on the manufactured prototypes, discussing the obtained differences, pointing out the importance of measured parameters de-embedding, appropriate modelling of discrete components and giving specific recipes for good modelling practices.