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Aberrations of the eye and other image-forming systems are often analyzed by expanding the wavefront aberration function for a given pupil in Zernike polynomials. In previous articles explicit analytical formulae to transform Zernike coefficients of up to seventh order corresponding to wavefront aberrations for an original pupil into those related to a contracted transversally displaced new pupil are obtained. In the present paper, selection rules for the direct and inverse coefficients' transformation are given and missing modes associated with certain displacement directions are analyzed. Taking these rules into account, a graphical method to qualitatively identify which are the elements of the transformation matrix and their characteristic dependence on pupil parameters is presented. This method is applied to fictitious systems having only one non-zero original coefficient and, for completeness, the new coefficient values are also analytically evaluated. [ABSTRACT FROM AUTHOR]

The accuracy of the popular graphical method of Swanepoel (SGM) for the characterization of a thin film on a substrate specimen from its interference transmittance spectrum depends on the subjective choice of four characterization parameters: the slope of the graph, the order number for the longest wavelength extremum, and the two numbers of the extrema used for the calculation approximations of the average film thickness. Here, an error metric is introduced for estimating the accuracy of SGM characterization. An algorithm is proposed for the optimization of SGM, named the OGM algorithm, based on the minimization of this error metric. Its execution provides optimized values of the four characterization parameters, and the respective computation of the most accurate film characteristics achievable within the framework of SGM. Moreover, substrate absorption is accounted for, unlike in the classical SGM, which is beneficial when using modern UV/visible/NIR spectrophotometers due to the relatively larger amount of absorption in the commonly used glass substrates for wavelengths above 1700 nm. A significant increase in the accuracy of the film characteristics is obtained employing the OGM algorithm compared to the SGM algorithm for two model specimens. Such improvements in accuracy increase with increasing film absorption. The results of the film characterization by the OGM algorithm are presented for two specimens containing RF-magnetron-sputtered a-Si films with disparate film thicknesses. The computed average film thicknesses are within 1.1% of the respective film thicknesses measured by SEM for both films. Achieving such high film characterization accuracy is particularly significant for the film with a computed average thickness of 3934 nm, since we are not aware of any other film with such a large thickness that has been characterized by SGM. [ABSTRACT FROM AUTHOR]

Prompt loss of beam injected fast ions approaches 100% in lithium tokamak experiment-beta (LTX- β) discharges, though significantly improved confinement is expected for the higher current plasmas made available by a recent upgrade to the Ohmic heating power supply. Modeling of fast ions using TRANSP/NUBEAM finds a maximum coupled beam fraction of 76% at the near-term limits of the LTX- β operating space. The full ion orbit code POET is employed to validate NUBEAM results against possible non-adiabatic effects on fast ion orbits, but corrections to the prompt loss fraction due to collisionless transport are found to be small. The graphical method code CONBEAM is used to investigate the topology of fast ion phase space as it relates to neutral beam deposition, and counter-injected NBI is considered as a way to access a region of high field side beam deposition. A metric is developed within the CONBEAM using a beam filament model to estimate the prompt loss fraction and shown to agree well with both POET and NUBEAM, enabling near real-time analysis and potential feedback to operators between plasma discharges. [ABSTRACT FROM AUTHOR]

We study the thermodynamics of a self-gravitating system of neutral fermions at finite temperature and analyze its backreaction in an asymptotically AdS space. We evaluate numerically the free entropy as a function of temperature, and perform a stability analysis applying the simpler and powerful graphical method referred as the Katz criterion. We found that for highly-enough degenerate fermionic solutions, the onset of thermodynamic instability arises, though prior to the turning point on the mass as a function of the central density. Our results for finite temperature fermions provide a novel and more general way to study the confinement to deconfinement phase transition in the holographic field theory, generalizing former conclusions developed for systems at zero temperature. [ABSTRACT FROM AUTHOR]

These are exciting times for quantum physics as new quantum technologies are expected to soon transform computing at an unprecedented level. Simultaneously network science is flourishing proving an ideal mathematical and computational framework to capture the complexity of large interacting systems. Here we provide a comprehensive and timely review of the rising field of complex quantum networks. On one side, this subject is key to harness the potential of complex networks in order to provide design principles to boost and enhance quantum algorithms and quantum technologies. On the other side this subject can provide a new generation of quantum algorithms to infer significant complex network properties. The field features fundamental research questions as diverse as designing networks to shape Hamiltonians and their corresponding phase diagram, taming the complexity of many-body quantum systems with network theory, revealing how quantum physics and quantum algorithms can predict novel network properties and phase transitions, and studying the interplay between architecture, topology and performance in quantum communication networks. Our review covers all of these multifaceted aspects in a self-contained presentation aimed both at network-curious quantum physicists and at quantum-curious network theorists. We provide a framework that unifies the field of quantum complex networks along four main research lines: network-generalized, quantum-applied, quantum-generalized and quantum-enhanced. Finally we draw attention to the connections between these research lines, which can lead to new opportunities and new discoveries at the interface between quantum physics and network science. [ABSTRACT FROM AUTHOR]

Calibration of 22 gamma camera units was performed at 15 hospitals in southern and western Sweden to estimate 137Cs contamination in humans in a supine static geometry, with a new developed calibration protocol and phantom. The minimum detectable activities (MDAs) and the estimated committed effective doses (CEDs) were calculated for each calibration. Generic calibration factors were calculated for five predetermined groups based on the detector type and manufacturer. Group 1 and 2 included NaI-based gamma cameras from General Electrics (GEs) with a crystal thickness of 5/8′′ and 3/8′′ respectively. Group 3 and 4 included NaI-based gamma cameras from Siemens Healthineers with a crystal thickness of 3/8′′, with a similar energy window as the GE NaI-based cameras and a dual window respectively. Group 5 included semiconductor-based gamma cameras from GE with a CdZnTe (CZT) detector. The generic calibration factors were 60.0 cps kBq−1, 52.3 cps kBq−1, 50.3 cps kBq−1, 53.2 cps kBq−1 and 48.4 cps kBq−1 for group 1, 2, 3, 4, and 5 respectively. The MDAs ranged between 169 and 1130 Bq for all groups, with measurement times of 1–10 min, corresponding to a CED of 4.77–77.6 μ Sv. A dead time analysis was performed for group 1 and suggested a dead time of 3.17 μ s for 137Cs measurements. The dead time analysis showed that a maximum count rate of 232 kcps could be measured in the calibration geometry, corresponding to a CED of 108–263 mSv. It has been shown that semiconductor-based gamma cameras with CZT detectors are feasible for estimating 137Cs contamination. The generic calibration factors derived in this study can be used for gamma cameras of the same models in other hospitals, for measurements in the same measurement geometry. This will increase the measurement capability for estimating internal 137Cs contamination in the recovery phase following radiological or nuclear events. [ABSTRACT FROM AUTHOR]

Cone-beam computed tomography (CBCT) is widely used in dental imaging, small animal imaging, radiotherapy, and non-destructive industrial inspection. The quality of CBCT images depends on the precise knowledge of the CBCT system's alignment. We introduce a distinct procedure, 'precision alignment loop (PAL)', to calibrate any CBCT system with a circular trajectory. We describe the calibration procedure by using a line-beads phantom, and how PAL determines the misalignments from a CBCT system. PAL also yields the uncertainties in the simulated calibration to give an estimate of the errors in the misalignments. From the analytical simulations, PAL can precisely obtain the source-to-rotation axis distance, and the geometric center G, 'the point in z -axis meets the detector', where the z -axis is coincident with the line from the x-ray source that intersects the axis of the rotation orthogonally. The uncertainties of three misalignment angles of the detector are within ±0.05°, which is close to ±0.04° for the results of Yang et al (2017 Med. Phys. 44 1692), but our method is easy and simple to implement. Our distinct procedure, on the other hand, yields the calibration of a micro-CT system and an example of reconstructed images, showing our calibration method for the CBCT system to be simple, precise, and accurate. [ABSTRACT FROM AUTHOR]

After investigating the behavior of ions during the growth of conductive filaments, we suggested a model for the growth process and electrical characteristics of the conductive filament under current-driven mode. In this model, the ionic displacement equation is derived by Arrhenius law, and a differential equation for the conductive filament growth has been established. We have also proved that the dielectric layer with the leakage current under current-driven mode can be equivalent to a parallel plate capacitor, which has a the equivalent dielectric constant. Consequently, the forming/set time of the device is gotten. At the same time, the kinetics process of ion motion is analyzed in detail, so that many microscopic parameters of the ion motion, such as the height of the potential barrier, the jump step, mobility and diffusion coefficient, can be obtained. Due to divalent and monovalent copper ions all participate in conduction, an equivalent copper ion Cuz+ is used for replacing both Cu+ and Cu2+, solving the computational complexity problem caused by multivalent metal ions. Finally, an equivalent circuit is proposed to calculate output voltage versus time characteristic. The calculation results of the model are consistent with experimental data. [ABSTRACT FROM AUTHOR]

It is usually assumed that deep defect levels are responsible for the high resistivity in detector-grade CdTe, however, it has been recently reported that shallow defects alone can explain high resistivity. In order to resolve this contradiction we analyze different high-temperature compensation regimes and we particularly show that donor–acceptor self-compensation is not a sufficient condition for high resistivity. We also analyze the dependence of the Fermi level on shallow donor concentration at both high temperature and room temperature using analytical solution of the charge neutrality equation and the graphical method based on the formation energy diagrams. We derive the limits of the high-temperature Fermi level values that lead to the high resistivity at room temperature in a system with shallow defect levels only and find that it is theoretically possible to obtain high resistivity using only shallow defects, but only under an extremely narrow range of physical parameters that is unlikely to occur in practice. Finally, we show that the transition levels of cadmium vacancy acceptor are not deep enough to provide high resistivity. [ABSTRACT FROM AUTHOR]

During the last two decades, rapid advancements in RT oscillators that use resonant tunneling diodes (RTDs) have been reported, with operations approaching the limits of electronic device oscillators. Although RTD devices are known for HF operation, milliwatt-level high-output powers have been recently obtained using a single device. Moreover, interesting operations using feedback and injection locking phenomena are also emerging. This paper outlines the basic oscillation principles, oscillation characteristics, and applications of RTD devices. Unlike previous reviews, the basic parts include harmonic signal generation, the construction of resonators and antennas, and bias circuits, which have been newly summarized. A graphical method for determining oscillation is introduced, and the oscillator characteristics are summarized in terms of new indicators, such as power density. This paper also includes the modulation characteristics of the intrinsic part of the device, spectral changes owing to feedback, and the characteristics of the RTD device as a receiver.