bluuebunny/crossref_metadata_2025_split huggingface dataset:
Built-in wavelet-induced smoothness to reduce plan complexity in intensity modulated radiation therapy (IMRT)
Authors: Tefagh Mojtaba , Zarepisheh Masoud 
Published: February 2023

Abstract

Objective. Reducing plan complexity in intensity modulated radiation therapy (IMRT) to ensure dosimetric accuracy and delivery efficiency of the radiation treatment plans. We propose a novel approach by representing the beamlet intensities using an incomplete wavelet basis that explicitly excludes fluctuating intensity maps from the decision space (explicit hard constraint). This technique provides a built-in wavelet-induced smoothness that improves both dosimetric plan quality and delivery efficiency. Approach. The beamlet intensity maps need to be especially smooth in the leaf travel direction (referred to as the X-direction). We treat the intensity map of each beam as a 2D image and represent it using the wavelets corresponding to low-frequency changes in the X-direction (i.e. approximation and horizontal). The absence of wavelets corresponding to high-frequency changes (i.e. vertical and diagonal) induces built-in smoothness. We still utilize a regularization term in the objective function to promote smoothness in the Y-direction (perpendicular to the X-direction) and further possible smoothness in the X-direction. This technique has been tested on three patient cases of different disease sites (paraspinal, lung, prostate) and all final evaluations and comparisons have been performed on an FDA-approved commercial treatment planning system (Varian EclipseTM). Main results. Wavelet-induced smoothness reduced monitor units by about 10%, 45%, and 14% for paraspinal, lung, and prostate cases, respectively. It also improved organ at risk sparing, especially on the complex paraspinal case where it resulted in about 7%, 13%, and 14% less mean dose to esophagus, lung, and cord, respectively. Moreover, built-in wavelet-induced smoothness desensitizes the results to changing the weight associated to the regularization term, and thereby mitigates the weight fine-tuning difficulty. Significance. Fluence smoothness is often achieved by smoothing the beamlet intensity maps using a proper regularization term in the objective function aiming at disincentivizing fluctuation in the beamlet intensities (implicit soft constraint). This work reports a novel application of wavelets in imposing an explicit smoothness hard constraint in the search space using an incomplete wavelet basis. This idea has been successfully applied to exclude complex and clinically irrelevant radiation plans from the search space. The code and pertained models along with a sample dataset are released on our LowDimRT GitHub (https://github.com/PortPy-Project/LowDimRT).
Multifunctional soft stretchable strain sensor for complementary optical and electrical sensing of fatigue cracks
Authors: Liu Han , Kollosche Matthias , Laflamme Simon , Clarke David R 
Published: February 2023

Abstract
Fatigue-induced cracking in steel components and other brittle materials of civil structures is one of the primary mechanisms of degrading structural integrity and can lead to sudden failures. However, these cracks are often difficult to detect during visual inspections, and off-the-shelf sensing technologies can generally only be used to monitor already identified cracks because of their spatial localization. A solution is to leverage advances in large area electronics to cover large surfaces with skin-type sensors. Here, the authors propose an elastic and stretchable multifunctional skin sensor that combines optical and capacitive sensing properties. The multifunctional sensor consists of a soft stretchable structural color film sandwiched between transparent carbon nanotube electrodes to form a parallel plate capacitor. The resulting device exhibits a reversible and repeatable structural color change from light blue to deep blue with an angle-independent property, as well as a measurable change in capacitance, under external mechanical strain. The optical function is passive and engineered to visually assist in localizing fatigue cracks, and the electrical function is added to send timely warnings to infrastructure operators. The performance of the device is characterized in a free-standing configuration and further extended to a fatigue crack monitoring application. A correlation coefficient-based image processing method is developed to quantify the strain measured by the optical color response. Results show that the sensor performs well in detecting and quantifying fatigue cracks using both the color and capacitive signals. In particular, the color signal can be measured with inexpensive cameras, and the electrical signal yields good linearity, resolution, and accuracy. Tests conducted on two steel specimens demonstrate a minimum detectable crack length of 0.84 mm.
Polarization and phase control of electron injection and acceleration in the plasma by a self-steepening laser pulse
Authors: Kim Jihoon , Wang Tianhong , Khudik Vladimir , Shvets Gennady 
Published: February 2023

Abstract
We describe an interplay between two injection mechanism of background electrons into an evolving plasma bubble behind an intense laser pulse: one due to the overall bubble expansion, and another due to its periodic undulation. The two mechanisms occur simultaneously when an intense laser pulse propagating inside a plasma forms a shock-like steepened front. Periodic undulations of the plasma bubble along the laser propagation path can either inhibit or conspire with electron injection due to bubble expansion. We show that carrier-envelope-phase (CEP) controlled plasma bubble undulation induced by the self-steepening laser pulse produces a unique electron injector—expanding phase-controlled undulating bubble (EPUB). The longitudinal structure of the electron bunch injected by the EPUB can be controlled by laser polarization and power, resulting in high-charge (multiple nano-Coulombs) high-current (tens of kilo-amperes) electron beams with ultra-short (femtosecond-scale) temporal structure. Generation of high-energy betatron radiation with polarization- and CEP-controlled energy spectrum and angular distribution is analyzed as a promising application of EPUB-produced beams.
Visualization of fast ion phase-space flow in plasmas well-below, near and well-above Alfvén eigenmode stability threshold in tokamak
Authors: Du X.D. , Heidbrink W.W. , Van Zeeland M.A. , Gonzalez-Martin J. , Austin M.E. , Yan Z. , McKee G.R. 
Published: February 2023

Abstract
Transport of fast ions along certain local phase space paths, referred to as fast ion phase-space flow, has been systematically measured by an imaging neutral particle analyzer (INPA) in three plasma regimes, which are well-below, near, and well-above the Alfvén eigenmode stability threshold (Du et al 2021 Phys. Rev. Lett.
127 235002). (1) In plasmas well-below the Alfvén eignenmodes (AE) stability threshold, fast ions are well-confined on passing particle orbits without noticeable transport over the phase space. The observed INPA images agree well with the synthetic INPA images, using the fast ion distribution predicted by neoclassical theory. (2) In plasmas near the AE stability threshold, INPA images in the presence of AE activity moderately deviate from those without AE activity. The image difference can be well interpreted by AE-driven, phase-space fast ion flow. Paths of this flow over the velocity space (or streamlines) are reconstructed by the intersection lines of curved Eʹ and µ surfaces, referred to as Eʹ and µ line (where

E

′

≡
E
−
(
ω

/

n
)

P

ζ

; E, P

ζ
and µ are the energy, canonical toroidal momentum and magnetic moment of ions; ω and n are the angular frequency and toroidal mode number of AEs, respectively). Resonant fast ions move radially inward by gaining energy and move radially outward by losing energy and the trajectory well aligns with the Eʹ and µ lines that pass through the mode resonances near the injection energy of neutral beams. (3) In plasmas well-above the AE stability threshold, fast ion phase-space dynamics shows additional features. Fast ions are transported out of the birth positions so promptly along the streamlines that the slowing-down process from the injection energy is not observable, exhibiting strong critical gradient behavior at local phase space. As a result, the increase of electron temperature is very small, in spite of an increase of beam power by

∼

45
%

. It should be emphasized that the directions of phase-space transport, induced by AEs with different frequencies, structures and mode numbers, do not largely differ.
Argon–seeded detachment during ELM control by RMPs in KSTAR
Authors: Shin H. , Hwang J. , Han Y. , Shin G. , Lee H. , Chai K.-B. , Choe Wonho 
Published: February 2023

Abstract
In this study, we demonstrate argon-seeded discharges that exhibited a detached divertor during the full suppression and mitigation of edge-localized modes (ELMs) by an International Thermonuclear Experimental Reactor-like, three-row resonant magnetic perturbation (RMP) configuration in KSTAR. During the ELM suppression phase, the peak heat flux on the divertor target was successfully reduced from 1.6 MW m−2–0.5 MW m−2 via argon seeding. Further, the ion saturation current densities corresponding to the particle fluxes on both targets were reduced by more than 50%. During the RMP grassy-ELM regime, a further reduction to 0.1 MW m−2 in the divertor heat load was successfully achieved. A highly localized radiation zone near the X-point was also observed during divertor detachment. The calculated degree of detachment based on the two-point model increased to levels of approximately 3 and 2.3 for the outer target and inner target cases, respectively. These results provide valuable information regarding the effect of mid-Z impurities on RMP-detachment-compatible discharges.
Theoretical evaluation of the tritium extraction from liquid metal flows through a free surface and through a permeable membrane
Authors: Urgorri F.R. , Garcinuño B. , Moreno C. , Rapisarda D. 
Published: February 2023

Abstract
Effective tritium extraction from PbLi flows is a requirement for the functioning of any PbLi based breeding blanket concept. For a continuous plant operation, the removal of the tritium dissolved in the PbLi has to be performed in line and sufficiently fast. Otherwise, tritium inventories in the liquid metal, start-up inventories and buffer inventories would be excessive from the safety point of view. Moreover, a slow response of the tritium extraction systems could also compromise the tritium self-sufficiency of the plant. A promising solution to this problem is to use highly permeable membranes in contact with the PbLi flow to promote the extraction via permeation. This technique is usually known as Permeation Against Vacuum (PAV). As an alternative, tritium could be extracted directly by permeation through a fluid free surface (FS) in contact with vacuum. In both configurations, the dynamics of tritium transport is ruled by a combination of convection, diffusion and surface recombination. In this paper, the tritium extraction processes in the FS and PAV configurations are studied in detail. For the first time, general analytical expressions for the extraction efficiency are derived for both techniques in a Cartesian geometry. These expressions are general in the sense that they do not impose any kind of assumption concerning the permeation regime of the membrane or the fluid boundary layer. The derived expressions have been used to analyze numerically the response of both configurations in a close loop system, such as the one of DEMO. The presented methodology allows comparing the FS and PAV configurations, assessing in which conditions one will be behave better than other.
Achievement of ion temperatures in excess of 100 million degrees Kelvin in the compact high-field spherical tokamak ST40
Authors: McNamara S.A.M. , Asunta O. , Bland J. , Buxton P.F. , Colgan C. , Dnestrovskii A. , Gemmell M. , Gryaznevich M. , Hoffman D. , Janky F. , Lister J.B. , Lowe H.F. , Mirfayzi R.S. , Naylor G. , Nemytov V. , Njau J. , Pyragius T. , Rengle A. , Romanelli M. , Romero C. , Sertoli M. , Shevchenko V. , Sinha J. , Sladkomedova A. , Sridhar S. , Takase Y. , Thomas P. , Varje J. , Vincent B. , Willett H.V. , Wood J. , Zakhar D. , Battaglia D.J. , Kaye S.M. , Delgado-Aparicio L.F. , Maingi R. , Mueller D. , Podesta M. , Delabie E. , Lomanowski B. , Marchuk O. ,   the ST40 Team
Published: February 2023

Abstract
Ion temperatures of over 100 million degrees Kelvin (8.6 keV) have been produced in the ST40 compact high-field spherical tokamak (ST). Ion temperatures in excess of 5 keV have not previously been reached in any ST and have only been obtained in much larger devices with substantially more plasma heating power. The corresponding fusion triple product is calculated to be

n

i
0

T

i
0

τ
E

≈
6
±
2
×

10

18

m

−
3

keVs

. These results demonstrate for the first time that ion temperatures relevant for commercial magnetic confinement fusion can be obtained in a compact high-field ST and bode well for fusion power plants based on the high-field ST.
An Introduction to PT-Symmetric Quantum Mechanics-Time-Dependent Systems
Authors: Fring A 
Published: February 2023

Abstract
I will provide a pedagogical introduction to non-Hermitian quantum systems that are PT-symmetric, that is they are left invariant under a simultaneous parity transformation (P) and time-reversal (T). I will explain how generalised versions of this antilinear symmetry can be utilised to explain that these type of systems possess real eigenvalue spectra in parts of their parameter spaces and how to set up a consistent quantum mechanical framework for them that enables a unitary time-evolution. In the second part I will explain how to extend this framework to explicitly time-dependent Hamiltonian systems and report in particular on recent progress made in this context. I will explain how to construct the essential key quantity in this framework, the time-dependent Dyson map and metric and solutions to the time-dependent Schrödinger equation, in an algebraic fashion, using time-dependent Darboux transformations, utilising Lewis-Riesenfeld invariants, point transformations and some approximation methods. I comment on the ambiguities of this metric and demonstrate that this can even lead to infinite series of metric operators. I conclude with some applications to PT-symmetrically coupled oscillators, demonstrate the equivalence of the time-dependent double wells and unstable anharmonic oscillators and show how the unphysical PT-symmetrically broken regions in the parameter space for the time-independent theory becomes physical in the explicitly time-dependent systems. I discuss how this leads to a prolongation of the otherwise rapidly decaying von Neumann entropy. The so-called sudden death of the entropy is stopped at a finite value.1
Optomechanical Simulation of a Parametric Oscillator
Authors: Onah F E , Ventura-Velázquez C , Maldonado-Villamizar F H , Jaramillo-Ávila B R , Rodríguez-Lara B M 
Published: February 2023

Abstract
We study an optomechanical device supporting at least three optical modes in the infrared telecommunication band and three mechanical vibration modes. We model the coherent driving of each optical mode, independently of each other, to obtain an effective Hamiltonian showing the different types of parametric processes allowed in the device. We propose a bichromatic driving scheme, in the lossy optical cavity regime, under a mean field approximation, that provides the quantum simulation of a parametric oscillator with optical control of its parameters.
Parameter Estimation via Indefinite Causal Structures
Authors: Procopio L M 
Published: February 2023

Abstract
Quantum Fisher information is the principal tool used to give the ultimate precision bound on the estimation of parameters for quantum channels. In this work, we present analytical expressions for the quantum Fisher information with three noisy channels for the case where the channels are in superposition of causal orders. We found that the quantum Fisher information increases as the number of causal orders increases for certain combinations. We also show that certain combinations of causal orders attain higher precision on bounds than others for the same number of causal orders. Based on our results, we chose the best combinations of causal orders with three channels for probing schemes using indefinite causal structures.
Symmetry Analysis of the Square Well Potential
Authors: Suárez E , Santiago-Acosta R D , Lemus R 
Published: February 2023

Abstract
Symmetry considerations are taken into account when a particle in a square well potential is studied. This system may display natural degeneracy, accidental degeneracy or systematic accidental degeneracy depending on the depth of the potential. In order to obtain the solutions associated with an arbitrary potential an algebraic discrete variable representation approach based on Pöschl-Teller functions is proposed. It is proved that the geometrical group C
4v
is the symmetry group of the system for the case of a finite potential barrier. A similar analysis is carried out for the rectangular square well potential with commensurate sides. In both cases the symmetry projection is crucial to simplify the calculations.
Dynamics of the Quantum Rabi Model in the Adiabatic Regime
Authors: Castanos-Cervantes L O 
Published: February 2023

Abstract
The quantum Rabi model in the adiabatic and ultrastrong and deep strong coupling regimes is considered. Some of the differences with the Jaynes-Cummings model are illustrated by considering the evolution of states and the expected values and root-mean-square deviations of several physical quantities of the qubit-oscillator system.
Modified Poisson-Gauss Single-Function to Describe the GRIN of the Human Lens
Authors: Jaimes-Nájera A 
Published: February 2023

Abstract
The human lens plays a crucial role in the vision process, since it is responsible for the accommodation mechanism and for the reduction of optical aberrations. Its modeling is important for the comprehension of the relationship between its physiological and optical properties, and ultimately for ophthalmic purposes. In this work we propose a modified version of the Poisson-Gauss function to construct a lens model that permits the fine-tuning of optical properties of the corresponding schematic eye. Particularly, we analyze how the refractive power of a schematic eye varies as the modification of the Poisson-Gauss function is induced. This can be useful in the modeling of personalized eyes with ophthalmic relevance.
Temperature Dependence of Entanglement and Coherence in Fenna-Matthews-Olson Complex
Authors: González-Soria B , Delgado F 
Published: February 2023

Abstract
The high efficiency in excitation energy transfer observed in the Fenna-Matthews-Olson light-harvesting complex in green sulfur bacteria is due to its arrange of photo-pigments, called bacteriochlorophylls. They are central for the photosynthetic process of those bacteria being controversially associated to long-lived coherence. The study of this protein complex and its energy dynamics continues, trying to understand the environmental factors affecting it. This work explores the temperature effects in the behaviour of entanglement and coherence among bacteriochlorophyll excitation energy transfer within the Fenna-Matthews-Olson complex, considering the latest pigment-protein monomer arrangement of 8 bacteriochlorophylls. An analysis for the system evolution using the Hierarchical Equations of Motion method, a non-Markovian approach, is performed to get the global and semi-local entanglement, as well as the coherence in the system.
Quantum Authentication Using Double Teleportation
Authors: Cardoso-Isidoro C , Delgado F 
Published: February 2023

Abstract
A process involving quantum teleportation to teleport a state to two parties in superposition is presented. Then, the process is applied to cryptography. Concretely in this work, we present the process of cryptography authentication using an undefined qubit state and the double quantum teleportation presented previously. Since quantum cryptography protocols are susceptible of eavesdropping, then such a process is considered through an eavesdropper trying to steal the information to supplant the user of authentication in order to quantify certain limits of applicability.
Groundwater shapes North American river floods
Authors: Berghuijs Wouter R , Slater Louise J 
Published: February 2023

Abstract
The importance of soil moisture in triggering river floods is increasingly recognized. However, soil moisture represents only a fraction of the water stored in the unsaturated zone. In contrast, groundwater from the deeper, saturated zone, may contribute a significant proportion of river flow, but its effects on flooding are poorly understood. Here we analyze hydroclimatic records of thousands of North American watersheds spanning 1981–2018 to show that baseflow (i.e. groundwater-sustained river flows) affects the magnitude of annual flooding at time scales from days to decades. Annual floods almost always arise through the co-occurrence of high precipitation (rainfall + snowmelt) and baseflow. Flood magnitudes are often more strongly related to variations in antecedent baseflow than antecedent soil moisture and short-term (⩽3-day) extreme precipitation. In addition, multi-decadal trends in flood magnitude and decadal flood variations tend to better align with groundwater storage and baseflow trends than with changing precipitation extremes and soil moisture. This reveals the importance of groundwater in shaping North American river floods and often decouples the spatial patterns of flood trends from those of shifting precipitation extremes and soil moisture.
Viscous flow through macroscopic spherical cavities in an arbitrary configuration in a granular material
Authors: Sano Osamu 
Published: February 2023

Abstract
Viscous flow through macroscopic spherical cavities in a granular material is theoretically investigated. Number, size and configuration of the cavities are arbitrary, except that cavities are sufficiently distant to allow asymptotic analysis on their interaction, which is taken into account up to

O
(
a

/

l

)
3

, where a and l are the characteristic radius and inter-cavity distance, respectively. Dependence of the flow field, flux into respective cavities and stress field etc on the cavity size, separation distance and orientation are analyzed. As further examples, 1D-, 2D-, and 3D-array of equal size cavities are examined, by which onset of the collapse of cavity and development of the collapsed region are elucidated. The latter may predict landslides and other flow-induced catastrophic changes in the material with quasi-equilibrium solid structure, as well as microscale waterway formation in human tissue known as angiogenesis.
On interfacial stress transmission of carbon nanotubes/alumina composites
Authors: Yang Yang , Xin Zhou , Gao-Feng Wei 
Published: February 2023

Abstract
The interface of carbon nanotube (CNTs)/alumina ceramic composites has a very important effect on their mechanical properties. In this study, an appropriate theoretical cell model was established to study the interfacial stress transmission in CNT/alumina composites. The stress transfer equation is derived as follows: The tensile stress of the CNTs and interfacial shear stress were simulated under an axial tension load, and the relationship between the stress transmission and the effective length of the CNTs was analyzed. The theoretical results were compared with the finite element method (FEM) results, and the results were found to be in good agreement. This study can provide a theoretical basis for adjusting the appropriate length of CNTs and interfacial interactions under different tension loads.