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Kramers–Kronig relations link the real and imaginary parts of the Fourier transform of a well-behaved causal transfer function describing a linear, time-invariant system. From the physical point of view, according to the Kramers–Kronig relations, absorption and dispersion become two sides of the same coin. Due to the simplicity of the assumptions underlying them, the relations are a cornerstone of physics. The rigorous mathematical proof was carried out by Titchmarsh in 1937 and just requires the transfer function to be square-integrable (L2), or equivalently that the impulse response of the system at hand has a finite energy. Titchmarsh's proof is definitely not easy, thus leading to crucial steps that are often overlooked by instructors and, occasionally, prompting some authors to attempt shaky shortcuts. Here, we share a rigorous mathematical proof that relies on the Laplace formalism and requires a slightly stronger assumption on the transfer function, namely it being Lebesgue-integrable (L1). While the result is not as general as Titchmarsh's proof, its enhanced simplicity makes a deeper knowledge of the mathematical aspects of the Kramers–Kronig relations more accessible to the audience of physicists. Editor's Note The Kramers–Kronig relations are fundamental to optics, linking dispersion to absorption. While incomplete proofs are found in many textbooks, the rigorous mathematical proof that requires the minimal assumption (that the transfer function is square-integrable) is quite challenging and, therefore, rarely taught. In this paper, the authors show that requiring a slightly stricter criterion for the transfer function (L1 = Lebesgue-integrable) allows the proof to be much more accessible. [ABSTRACT FROM AUTHOR]

Objective. Relative biological effectiveness (RBE) differs between radiation qualities. However, an RBE of 1.0 has been established for photons regardless of the wide range of photon energies used clinically, the lack of reproducibility in radiobiological studies, and outdated reference energies used in the experimental literature. Moreover, due to intrinsic radiosensitivity, different cancer types have different responses to radiation. This study aimed to characterize the RBE of clinically relevant high and low photon energies in vitro for three human cancer cell lines: HCT116 (colon), HeLa (cervix), and PC3 (prostate). Approach. Experiments were conducted following dosimetry protocols provided by the American Association of Physicists in Medicine. Cells were irradiated with 6 MV x-rays, an 192Ir brachytherapy source, 225 kVp and 50 kVp x-rays. Cell survival post-irradiation was assessed using the clonogenic assay. Survival fractions were fitted using the linear quadratic model, and survival curves were generated for RBE calculations. Main results. Cell killing was more efficient with decreasing photon energy. Using 225 kVp x-rays as the reference, the HCT116 RBESF0.1 for 6 MV x-rays, 192Ir, and 50 kVp x-rays were 0.89 ± 0.03, 0.95 ± 0.03, and 1.24 ± 0.04; the HeLa RBESF0.1 were 0.95 ± 0.04, 0.97 ± 0.05, and 1.09 ± 0.03, and the PC3 RBESF0.1 were 0.84 ± 0.01, 0.84 ± 0.01, and 1.13 ± 0.02, respectively. HeLa and PC3 cells had varying radiosensitivity when irradiated with 225 and 50 kVp x-rays. Significance. This difference supports the notion that RBE may not be 1.0 for all photons through experimental investigations that employed precise dosimetry. It highlights that different cancer types may not have identical responses to the same irradiation quality. Additionally, the RBE of clinically relevant photons was updated to the reference energy of 225 kVp x-rays. [ABSTRACT FROM AUTHOR]

Medical imaging is both valuable and essential in the care of patients. Much of this imaging depends on ionizing radiation with attendant responsibilities for judicious use when performing an examination. This responsibility applies in settings of both individual as well as multiple (recurrent) imaging with associated repeated radiation exposures. In addressing the roles and responsibilities of the medical communities in the paradigm of recurrent imaging, both the International Atomic Energy Agency (IAEA) and the American Association of Physicists in Medicine (AAPM) have issued position statements, each affirmed by other organizations. The apparent difference in focus and approach has resulted in a lack of clarity and continued debate. Aiming towards a coherent approach in dealing with radiation exposure in recurrent imaging, the IAEA convened a panel of experts, the purpose of which was to identify common ground and reconcile divergent perspectives. The effort has led to clarifying recommendations for radiation exposure aspects of recurrent imaging, including the relevance of patient agency and the provider-patient covenant in clinical decision-making. Clinical relevance statement: An increasing awareness, generating some lack of clarity and divergence in perspectives, with patients receiving relatively high radiation doses (e.g., ≥ 100 mSv) from recurrent imaging warrants a multi-stakeholder accord for the benefit of patients, providers, and the imaging community. Key Points: • Recurrent medical imaging can result in an accumulation of exposures which exceeds 100 milli Sieverts. • Professional organizations have different perspectives on roles and responsibilities for recurrent imaging. • An expert panel reconciles differing perspectives for addressing radiation exposure from recurrent medical imaging. [ABSTRACT FROM AUTHOR]

In the September 2022 issue of The Physics Teacher (TPT), Richard Kaufman and Harvey Leff showed the interdependence of the first and second laws of thermodynamics. Here, I go further and use the facts that the first law implies the second law, and that the second law implies the first law. This two-way implication establishes the logical equivalence of the first and second laws. Although the laws are logically equivalent (when one is true, then the other must be true), this does not mean that they are the same. The equivalence provides for a deeper and richer understanding of the laws of thermodynamics for students, teachers, and physicists. Surely, if we can know that the first and second laws are equivalent, then we should know. [ABSTRACT FROM AUTHOR]

The generalized mK(m,n) model is used to portray the movement of nonlinear waves by applying four mathematical methods with assistance of Mathematica software. These methods are called enhanced simple equation (SE) method, Exp(−Ψ(ξ))-expansion method, (G′∕G)-expansion method and modified F-expansion method. For physical behavior, few solutions are plotted graphically in the form of two-dimensional (2D) and three-dimensional (3D). The techniques and soliton solutions that are developed provide computational tools for additional research in this area. With this work, we have gained a better knowledge of soliton motion and how it is used in dynamical systems and other related technologies. Hence, this work will help physicists envision some new ideas and hypotheses in nonlinear science. [ABSTRACT FROM AUTHOR]

The magnetohydrodynamics system forced by space-time white noise has been studied by physicists for decades, and the rigorous proof of its solution theory was recently established by Yamazaki (2023, Electron. J. Probab., 28 , 1–66). When an equation is well-posed, and it is approximated by replacing the differentiation operator by reasonable discretization schemes, it is widely believed that a solution of the approximating equation should converge to the solution of the original equation as the discretization parameter approaches zero. We prove otherwise for the three-dimensional magnetohydrodynamics system forced by space-time white noise. Specifically, we prove that the limit of the solution to the approximating system with an additional 32 drift terms solves the original system. These 32 drift terms depend on the choice of approximations, can be calculated explicitly and essentially represent a spatial version of Itô-Stratonovich correction terms. [ABSTRACT FROM AUTHOR]

Introduction: Medical phantoms play a crucial role in medical imaging and therapy. However, the successful development of these phantoms heavily relies on a comprehensive understanding of the requirements specific to each application. Methods: In this paper, we emphasize the significance of requirement analysis in medical phantom development and develop a novel approach for gathering and classifying requirements specific for phantom development. Results: The implemented survey tool is designed to accommodate the diverse needs of stakeholders involved in phantom development, including medical staff, physicists, engineers, and product developers. To validate the effectiveness of the approach, we conduct the development of a multimodal deformable pelvic phantom, providing insights into the process and its applicability. Discussion: The results demonstrate the utility and reliability of our approach in systematically gathering, categorizing, and prioritizing requirements, thus facilitating the streamlined and efficient development of medical phantoms. [ABSTRACT FROM AUTHOR]

Backgrounds: When comparing the delivery of all beams per fraction (ABPF) to single beam per fraction (SBPF), it is observed that SBPF not only helps meet the FLASH dose threshold but also mitigates the uncertainty with beam switching in the FLASH effect. However, SBPF might lead to a higher biological equivalent dose in 2 Gy (EQD2) for normal tissues. Purpose: This study aims to develop an EQD2‐based integrated optimization framework (EQD2‐IOF), encompassing robust dose, delivery efficiency, and beam orientation optimization (BOO) for Bragg peak FLASH plans using the SBPF treatment schedule. The EQD2‐IOF aims to enhance both dose sparing and the FLASH effect. Methods: A superconducting gantry was employed for fast energy switching within 27 ms, while universal range shifters were utilized to improve beam current in the implementation of FLASH plans with five Bragg peak beams. To enhance dose delivery efficiency while maintaining plan quality, a simultaneous dose and spot map optimization (SDSMO) algorithm for single field optimization was incorporated into a Bayesian optimization‐based auto‐planning algorithm. Subsequently, a BOO algorithm based on Tabu search was developed to select beam angle combinations (BACs) for 10 lung cases. To simultaneously consider dose sparing and FLASH effect, a quantitative model based on dose‐dependent dose modification factor (DMF) was used to calculate FLASH‐enhanced dose distribution. The EQD2‐IOF plan was compared to the plan optimized without SDSMO using BAC selected by a medical physicist (Manual plan) in the SBPF treatment schedule. Meanwhile, the mean EQD2 in the normal tissue was evaluated for the EQD2‐IOF plan in both SBPF and ABPF treatment schedules. Results: No significant difference was found in D2% and D98% of the target between EQD2‐IOF plans and Manual Plans. When using a minimum DMF of 0.67 and a dose threshold of 4 Gy, EQD2‐IOF plans showed a significant reduction in FLASH‐enhanced EQD2mean of the ipsilateral lung and normal tissue by 10.5% and 11.5%, respectively, compared to Manual plans. For normal tissues that received a dose greater than 70% of the prescription dose, using a minimum DMF of 0.7 for FLASH sparing compensated for the increase in EQD2mean resulting from replacing ABPF with SBPF schedules. Conclusions: The EQD2‐IOF can automatically optimize SBPF FLASH‐RT plans to achieve optimal sparing of normal tissues. With an energy switching time of 27 ms, the loss of fractionate repairing using SBPF schedules in high‐dose regions can be compensated for by the FLASH effect. However, when an energy switching time of 500 ms is utilized, the SBPF schedule needs careful consideration, as the FLASH effect diminishes with longer irradiation time. [ABSTRACT FROM AUTHOR]

Background: Optically stimulated luminescent dosimeters (OSLDs) can be bleached and reused, but questions remain about the effects of repeated bleaching and fractionation schedules on OSLD performance. Purpose: The aim of this study was to investigate how light sources with different wavelengths and different fractionation schemes affect the performance of reused OSLDs. Methods: OSLDs (N = 240) were irradiated on a cobalt‐60 beam in different step sizes until they reached an accumulated dose of 50 Gy. Between irradiations they were bleached using light sources of different wavelengths: the Imaging and Radiation Oncology Core (IROC) bleaching system (our control); monochromatic red, green, yellow, and blue lights; and a polychromatic white light. Sensitivity and linearity‐based correction factors were determined as a function of dose step‐size. The rate of signal removal from different light sources was characterized by sampling these OSLDs at various time points during their bleaching process. Relative doses were calculated according to the American Association of Physicists in Medicine Task Group‐191. Signal repopulation was investigated by irradiating OSLDs (N = 300) to various delivered doses of 2, 10, 20, 30, 40, and 50 Gy in a single fraction, bleached with one of the colors, and read over time. Fractionation effects were evaluated by irradiating OSLDs up to 30 Gy in different size steps. After reading, the OSLDs were bleached following IROC protocol. OSLDs (N = 40) received irradiations in 5, 10, 15, 30 Gy fractions until they had an accumulated dose of 30 Gy; The sensitivity response of these OSLDs was compared with reference OSLDs that had no accumulated dose. Results: Light sources with polychromatic spectrums (IROC and white) bleached OSLDs faster than did sources with monochromatic spectra. Polychromatic light sources (white light and IROC system) provided the greatest dose stability for OSLDs that had larger amounts of accumulated dose. Signal repopulation was related to the choice of bleaching light source, timing of bleaching, and amount of accumulated dose. Changes to relative dosimetry were more pronounced in OSLDs that received larger fractions. At 5‐Gy fractions and above, all OSLDs had heightened sensitivity, with OSLDs exposed to 30‐Gy fractions being 6.4% more sensitive than reference dosimeters. Conclusions: The choice of bleaching light plays a role in how fast an OSLD is bleached and how much accumulated dose an OSLD can be exposed to while maintaining stable signal sensitivity. We have expanded upon investigations into signal repopulation to show that bleaching light plays a role in the migration of deep traps to dosimetric traps after bleaching. Our research concludes that the bleaching light source and fractionation need to be considered when reusing OSLD. [ABSTRACT FROM AUTHOR]

The quaternionic Schrödinger equation ∂ ∂ t | f ⟩ = - A | f ⟩ is the crucial part of the study of quaternionic quantum mechanics and plays indispensable roles in related fields. One of the practical and special cases that has received more attention from mathematicians and physicists is that A is a Hermitian quaternion matrix. The problem can be equivalent to a Hermitian quaternion right eigenvalue problem A α = α λ by discretization. This paper, by means of a complex representation method, studies the Hermitian quaternion Schrödinger equation problem, and proposes a novel algebraic method (complex structure-preserving method) for right eigenvalue problems of Hermitian quaternion matrices. Moreover, the complex structure-preserving method is superior and formally simple compared to previous methods, and numerical experiments also demonstrate the effectiveness of the method. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to show the framework of the six‐sigma methodology (SSM) that can be used to determine the limits of QC tests for the linear accelerator (Linac). Limits for QC tests are individually determined using the SSM. Methods and Materials: The SSM is based on the define‐measure‐analyze‐improve‐control (DMAIC) stages to improve the process. In the "define" stage, the limits of QC tests were determined. In the "measure" stage, a retrospective collection of daily QC data using a Machine Performance Check platform was performed from January 2020 to December 2022. In the "analyze" stage, the process of determining the limits was proposed using statistical analyses and process capability indices. In the "improve" stage, the capability index was used to calculate the action limits. The tolerance limit was established using the larger one of the control limits in the individual control chart (I‐chart). In the "control" stage, daily QC data were collected prospectively from January 2023 to May 2023 to monitor the effect of action limits and tolerance limits. Results: A total of 798 sets of QC data including beam, isocenter, collimation, couch, and gantry tests were collected and analyzed. The Collimation Rotation offset test had the min‐Cp, min‐Cpk, min‐Pp, and min‐Ppk at 2.53, 1.99, 1.59, and 1.25, respectively. The Couch Rtn test had the max‐Cp, max‐Cpk, max‐Pp, and max‐Ppk at 31.5, 29.9, 23.4, and 22.2, respectively. There are three QC tests with higher action limits than the original tolerance. Some data on the I‐chart of the beam output change, isocenter KV offset, and jaw X1 exceeded the lower tolerance and action limit, which indicated that a system deviation occurred and reminded the physicist to take action to improve the process. Conclusions: The SSM is an excellent framework to use in determining the limits of QC tests. The process capability index is an important parameter that provides quantitative information on determining the limits of QC tests. [ABSTRACT FROM AUTHOR]

Interfacial solar water evaporation has emerged as an effective technique for converting solar energy to thermal energy, which can then be applied to clean water production and sewage treatment. This review discusses the primary characterization techniques used to evaluate the key aspects of interfacial solar water evaporators: the intrinsic and performance evaluation. Each technique is discussed with a brief explanation of its foundations, followed by carefully selected examples. This review is aimed at assisting materials chemists and physicists, particularly students, in choosing the most appropriate techniques for characterizing photothermal materials. [ABSTRACT FROM AUTHOR]

The Trinity test site was chosen, in part, for its supposed remove from human inhabitation. Yet nearly half-a-million people were living within a 150-mile radius of the explosion, with some as close as 12 miles away. None were warned or evacuated by the US government ahead of time. After the blast went off, fallout snowed down across the landscape for days, contaminating water and food sources. Children played with the hot flakes. Then pets and livestock began to die. Still, no one was told the truth, nor were government efforts made to evacuate the surrounding populations—despite warnings from Manhattan Project doctors and physicists that the radiation hazard for these civilians was, in their words, "very significant." Nearly eight decades later, Trinity test "downwinders" still await government recognition and restitution. [ABSTRACT FROM AUTHOR]

Keywords: Oppenheimer; Manhattan Project; Los Alamos; Trinity; atomic bomb; Roy Glauber EN Oppenheimer Manhattan Project Los Alamos Trinity atomic bomb Roy Glauber 221 231 11 07/19/23 20230701 NES 230701 During the middle of World War II, teenage physics major Roy Glauber found himself plucked out of college on the East Coast and assigned to work at a mysterious new government research center in the far-off deserts of New Mexico. In this interview, one of the last surviving eyewitnesses from the effort to build the first atomic bomb gives his impressions of that project's driving force - and of the director of the Los Alamos lab, J. Robert Oppenheimer. Oppenheimer, Manhattan Project, Los Alamos, Trinity, atomic bomb, Roy Glauber. [Extracted from the article]

In 1954, Robert Oppenheimer was subjected to what was rightly called "an extraordinary American inquisition" under the name of a security hearing. Despite having served his country so devotedly in heading the atomic bomb project at Los Alamos, he was now publicly humiliated, condemned as a security risk, stripped of his security clearance, and forced to step down from his government consultancies. Those hearings were skewed and manipulated in McCarthyite fashion. But while extremely harmful professionally and personally, the hearings were not Oppenheimer's greatest tragedy. His greatest tragedy was the success of his leadership in the creation of the weapon. His remarkable gifts as a physicist and as a human being were most realized in the building of a weapon that could lead to the destruction of humankind. We should make Oppenheimer's legacy to us the recognition that our only form of what has been called "nuclear ethics" is abolition. [ABSTRACT FROM AUTHOR]

Pulsars are believed to be one of the most important celestial objects in the universe. The emission mechanism of pulsars is still a big paradox for physicists, as no completely acceptable theory can reach a suitable consensus with observation. Some complicated coherent plasma processes and acceleration-based mechanisms in the pulsar magnetosphere generate a powerful radio beam. There have been dedicated theories such as the geometrical and relativistic phase shift (RPS) methods. The relativistic phase shift method is owing to the combined effects of aberration-retardation (A/R) and polar cap current effect (PCC), etc., and by implementing this method, we make quantitative inspections to deduce the emission altitude of the pulsar's radio emission components. Here, we have shown the estimation of the emission height of pulsar PSR B2111+46 for both core and conal components at 925 MHz, 1.25 GHz, 1.65 GHz, and 4.85 GHz. Moreover, we have estimated the foot point, normalized with the last open field line constant, corresponding to pulse edges at multiple bands. Current analysis of the paper shows that at least for PSR B2111+46, the full polar cap is not sensitive to radio emission for most of the cases in the given stretch of radio frequency. [ABSTRACT FROM AUTHOR]

Women remain underrepresented in medical physics in the United States, and determinants of persisting disparities remain unclear. Here, we performed a detailed investigation of American Association of Physicists in Medicine (AAPM) membership trajectories to evaluate trends in Full membership with respect to gender, age, and highest degree. Membership data, including gender, date of birth, highest degree, membership type, and years of active membership for 1993 to 2023 were obtained from AAPM. Group 1 included Full members who joined AAPM in 1993 or later. A subset of group 1 including only members who joined and left AAPM since 1993 (former members, group 1 F) was used to calculate age at membership cessation and duration. Results were compared by gender and highest degree. A Kaplan-Meier analysis was also used to evaluate membership "survival" by age and highest degree. Complete data were available for 6647 current and former Full members (group 1), including 2211 former members (group 1 F). On average, women became Full members at a significantly younger age than men (34.6 vs 37.5 years of age, P <.001) and ended their memberships (if applicable) at a significantly younger age than men (46.1 vs 50.1 years of age, P <.001). The Kaplan-Meier "survival" analysis showed that for a given age, women were at a significantly greater risk of membership cessation than men, and women with master's degrees had the lowest membership survival of any gender/degree subgroup. When analyzing by membership duration, there was no difference in survival by gender alone. Still, women with PhDs were found to have the greatest membership survival among gender/degree subgroups. Both gender and degree type influenced AAPM membership trajectories. Although we have offered a discussion of possible explanations, qualitative data collected from both continuing and departing AAPM members will be critical in the ongoing journey toward gender parity in the profession of medical physics. [ABSTRACT FROM AUTHOR]

In an article in this journal [Verheest, Am. J. Phys. 90, 425–429 (2022)], Frank Verheest presented a proof for the linearity of the Lorentz transformation. We fill in some gaps in his derivation and analyze the role of the light postulate that some physicists, including Verheest, have criticized as a necessary hypothesis for formulating the theory of relativity. Editor's Note: This Comment expands on a recent article on the Lorentz transformation, clearly explaining the roles in the transformation of the light principle, the limiting speed c, and linearity. [ABSTRACT FROM AUTHOR]

Whether there exist elementary particles having Majorana nature is a fundamental open question that has persisted since the 1930s. The only practical experiments to test the Majorana nature of neutrinos is the search for neutrinoless double-beta decay, which has been a major challenge for nuclear and particle physicists. In the 2000s, a number of experiments using advanced technologies were planned, some of which have already achieved significant improvements in the search sensitivity. In this article, the current status of the neutrinoless double-beta decay searches is summarized, reviewing the progress of KamLAND-Zen, which recorded the world's best sensitivity in the effective Majorana neutrino mass limit. [ABSTRACT FROM AUTHOR]

In this article I will focus on the debate on the causality principle that originated in the light of quantum mechanics concerning Moritz Schlick and Karl Popper. The discovery of quantum mechanics led to a broad debate on the interpretation of the principle of causality. Schlick proposed that it should be understood as an empirically verifiable postulate, and therefore with limits regarding causal indeterminacy in quantum physics. This approach had an influence on some scientists, especially Werner Heisenberg. However, Popper would develop a different way of understanding science because of the role played by unverifiable elements in theories that can nevertheless be falsified. It is precisely the discussion around the principle of causality that opens up different ways of understanding science. I will first try to analyse Schlick’s argument in the context of the debate that was taking place in the late 1920s in the light of the new quantum mechanics; secondly, I will look at the reception that Schlick’s idea of causality had in Heisenberg and the Copenhagen Interpretation; thirdly, I will analyse Popper’s argument against Schlick’s interpretation; finally, I will try to see the resonances of this debate in Heisenberg and other physicists. [ABSTRACT FROM AUTHOR]

Peter Higgs was a British theoretical physicist, renowned for his 1964 work in which he proposed a mechanism capable of generating masses for elementary particles while conforming to gauge symmetry. Half a century later, two experiments at CERN confirmed that this mechanism is realized in nature. On April 8th, we received the sad news of the passing of this great pioneer in elementary particle physics. This article is dedicated to his memory, and to the mechanism and particle that bear his name. [ABSTRACT FROM AUTHOR]

Machine learning (ML) methodologies, in recent years, have carved a significant niche within the realm of neutrino physics. These tools are not just ancillary but pivotal to the success of emerging experimental endeavors in the field. An overwhelming portion of current neutrino experiments rely heavily on an array of state-of-the-art machine learning tools. These sophisticated ML tools have empowered researchers to derive physical insights of unparalleled depth and clarity, significantly outpacing the potential of traditional data analytics approaches. Central to this achievement are the advanced neural network designs being employed. With the rapid evolution of machine learning techniques across diverse sectors, it is of paramount importance for neutrino physicists to remain updated and adapt these innovations seamlessly into their research workflows. The pace and vigor of advancements in machine learning, especially its applications in neutrino research, are nothing short of remarkable. Given this dynamic landscape, there's a continuous imperative to periodically distill, synthesize, and keep tabs on emerging trends. This paper, in essence, is an endeavor to provide such a synthesized overview, capturing the zeitgeist of ML applications in neutrino physics. [ABSTRACT FROM AUTHOR]

The highly heterogeneous dose delivery of spatially fractionated radiation therapy (SFRT) is a profound departure from standard radiation planning and reporting approaches. Early SFRT studies have shown excellent clinical outcomes. However, prospective multi-institutional clinical trials of SFRT are still lacking. This NRG Oncology/American Association of Physicists in Medicine working group consensus aimed to develop recommendations on dosimetric planning, delivery, and SFRT dose reporting to address this current obstacle toward the design of SFRT clinical trials. Working groups consisting of radiation oncologists, radiobiologists, and medical physicists with expertise in SFRT were formed in NRG Oncology and the American Association of Physicists in Medicine to investigate the needs and barriers in SFRT clinical trials. Upon reviewing the SFRT technologies and methods, this group identified challenges in several areas, including the availability of SFRT, the lack of treatment planning system support for SFRT, the lack of guidance in the physics and dosimetry of SFRT, the approximated radiobiological modeling of SFRT, and the prescription and combination of SFRT with conventional radiation therapy. Recognizing these challenges, the group further recommended several areas of improvement for the application of SFRT in cancer treatment, including the creation of clinical practice guidance documents, the improvement of treatment planning system support, the generation of treatment planning and dosimetric index reporting templates, and the development of better radiobiological models through preclinical studies and through conducting multi-institution clinical trials. [ABSTRACT FROM AUTHOR]

This article presents an unpublished manuscript by Alfred M. Bork that was written in 1976 as an introduction to a collection of Maxwell's papers on electromagnetism which was never published. It provides encouragement to the reader to study the original works of Maxwell on electromagnetism, and this encouragement is as timely today as in 1976. Editor's note: Maxwell's papers on electromagnetism are foundational to physics, and modern physicists have much to learn from reading them. This paper shares a nearly 50-year-old introduction to the papers written by Alfred Bork but never published. The manuscript was transcribed and edited by Kirk McDonald, who also added extensive footnotes and citations. The paper will help both students and faculty who wish to read and learn from Maxwell's original papers. [ABSTRACT FROM AUTHOR]

Professor Bimla Buti, affectionately known as Buti Ji to our generation, embarked on her research career in plasma physics in the late 1950s, a period when the field was still in its infancy. Previously referred to as the 'physics of electrical discharges', plasma physics was undergoing a transformative evolution, with foundational concepts being developed by esteemed pioneers. It was during this pivotal phase that Prof. Buti fearlessly chose to delve into this uncharted realm, making several seminal contributions along the way. One of her notable achievements is in the area of relativistic effects on plasma waves, where she has made a fundamental contribution by estimating the damping rate of relativistic plasma waves due to finite temperature effects. This is a significant endeavor that holds particular relevance in the realm of plasma-based particle accelerators today. Professor Buti's enduring dedication to her work continues to serve as a beacon of inspiration for aspiring physicists, captivating them not only with her scholarly contributions but also with her remarkable persona. [ABSTRACT FROM AUTHOR]

Color and shape, being inseparable, are the essential elements of human optical perception. In painting, color is the main tool of expression and the most significant element. The meaning of colors depends on a complex of physiological, psychological and cultural-social factors. Psychologists see color not as a simple sensation, but as a complex and multilateral perception, inextricably linked to socio-cultural and aesthetic aspects. The phenomenon of color has been studied by many artists, painters, researchers, psychologists, philosophers, physicists, who over time, through various researches regarding the influence of colors on the human psyche, have come to the conclusion that color exists both in the external, objective world of reality, as well as in the inner, subjective world of human, generating multiple emotional, psychological and intimate effects in the human personality. [ABSTRACT FROM AUTHOR]

Background: Particle accelerators, manufactured for delivering patient radiation treatment, require numerous and frequent quality assurance measures. One of those is the periodic check for electron energy stability. The American Association of Physicists in Medicine has established requirements for this procedure. The current recommendation is to perform a ratio of two ionization points, one at Dmax and another at a point approximately to the 50% depth, compared to a baseline as a relative check. Purpose: This ratio method is a sensitive measurement and sometimes produces results that are difficult to interpret or relate to acceptable tolerances. We sought to find a simple method that gives more stable results, which can be interpreted and related to energy changes. Method: We propose a method that takes two measurements on the descending portion of the shifted percent depth ionization (PDI) curves to calculate the slope, tangent to the I50 point, the point at which the ionization falls to 50% of its maximum value. We then used the slope measurement, compared to an established baseline, to relate energy. Results: After collecting data over a 3‐year period, we saw that standard deviations for the slope method have much less variability than the traditional ratio method. We were also able to correlate the slope results to ionization scans performed in water and found they were in better agreement than the traditional ratio method. Conclusion: The slope method does not require precise positioning since the slope remains relatively constant over the descending portion of the curve. Our data show that this results in an easier interpretative test of electron energy stability and delivers reliable feedback for quality assurance. [ABSTRACT FROM AUTHOR]

A number of recent papers or monographs have examined Susan Stebbing's criticisms of Arthur Eddington's scientific-philosophical writing. These papers focus on Stebbing's critique of Eddington's attempt to infer philosophical conclusions from developments in modern physics, his view that there is a discrepancy between the world of science and the world of common sense (best encapsulated by his famous ‘two tables’ metaphor), and his use of ‘inexact language’ to try and convey modern scientific insights to his readers. On November 10th 1938, Eddington presented a paper at the Moral Sciences Club in Cambridge entitled “Prof. Stebbing's ‘Philosophy and the Physicists'”. Eddington did not go on to publish this paper and it is not discussed in relevant scholarship. However, the details of Eddington’s talk are outlined in the minutes of that meeting. I argue that these minutes provide new insights into both the Stebbing-Eddington debate and developments in Eddington's late philosophical views. A full transcription of the minutes is included as an Appendix to this paper. [ABSTRACT FROM AUTHOR]

The onset and the development of the concept of exchange force in quantum physics are historically reconstructed, starting from Heisenberg's seminal contributions in 1926 and going through the great developments in nuclear physics, which allowed the emergence of the idea of force mediating virtual quanta. Although most of such work was performed in Europe, the last and decisive effort in this long path was carried out by Japanese scientists in the 1930s. This is the main focus of the present work, which retraces the achievements of Yukawa and Tomonaga, whose results and mutual interactions are carefully analyzed and related to those of European physicists. [ABSTRACT FROM AUTHOR]

Perturbation theory (PT) might be one of the most powerful and fruitful tools for both physicists and chemists, which has led to a wide variety of applications. Over the past decades, advances in quantum computing provide opportunities for alternatives to classical methods. Recently, a general quantum circuit estimating the low order PT corrections has been proposed. In this article, we revisit the quantum circuits for PT calculations, and develop the methods for higher order PT corrections of eigenenergy, especially the 3rd and 4th order corrections. We present the feasible quantum circuit to estimate each term in these PT corrections. There are two the fundamental operations in the proposed circuit. One approximates the perturbation terms, the other approximates the inverse of unperturbed energy difference. The proposed method can be generalized to higher order PT corrections. [ABSTRACT FROM AUTHOR]

We scan Paul K. Feyerabend's work in philosophy of physics and of science more generally for insights that could be useful for the contemporary debate on the foundations of quantum mechanics. We take as our starting point what Feyerabend has actually written about quantum mechanics, but we extend our analysis to his general views on realism, objectivity, pluralism, and the relation between physics and philosophy, finding that these more general views could in fact offer many interesting insights for physicists and philosophers working on quantum foundations. [ABSTRACT FROM AUTHOR]

Ferroelectricity, which has diverse important applications such as memory elements, capacitors, and sensors, was first discovered in a molecular compound, Rochelle salt, in 1920 by Valasek. Owing to their superiorities of lightweight, biocompatibility, structural tunability, mechanical flexibility, etc., the past decade has witnessed the renaissance of molecular ferroelectrics as promising complementary materials to commercial inorganic ferroelectrics. Thus, on the 100th anniversary of ferroelectricity, it is an opportune time to look into the future, specifically into how to push the boundaries of material design in molecular ferroelectric systems and finally overcome the hurdles to their commercialization. Herein, we present a comprehensive and accessible review of the appealing development of molecular ferroelectrics over the past 10 years, with an emphasis on their structural diversity, chemical design, exceptional properties, and potential applications. We believe that it will inspire intense, combined research efforts to enrich the family of high-performance molecular ferroelectrics and attract widespread interest from physicists and chemists to better understand the structure–function relationships governing improved applied functional device engineering. [ABSTRACT FROM AUTHOR]

Wittgenstein said in the Investigations, 'A philosophical problem has the form: "I don't know my way about"' (§ 123). The problem of mirror reversal—specifically the twentieth‐century transatlantic controversy between the psychologist Richard Gregory, the mathematical columnist Martin Gardner, the physicist Richard Feynman and various analytic philosophers, including David Pears, Ned Block and Don Locke—is presented here as an instructive case of our not knowing our way about. 'Why do mirrors reverse left and right but not up and down?' We discover that our perplexity disappears as we get clearer about the employment of the familiar oppositions left and right, up and down, back and front, and others. Finding our way about in these logico‐grammatical fells, we see connections with our troubles in more vertiginous landscapes. Our disquietude may not be deep (§ 111) but the 'battle against the bewitchment of our intelligence' (§ 109) is surprisingly severe. [ABSTRACT FROM AUTHOR]

Brachytherapy utilizes a multitude of radioactive sources and treatment techniques that often exhibit widely different spatial and temporal dose delivery patterns. Biophysical models, capable of modeling the key interacting effects of dose delivery patterns with the underlying cellular processes of the irradiated tissues, can be a potentially useful tool for elucidating the radiobiological effects of complex brachytherapy dose delivery patterns and for comparing their relative clinical effectiveness. While the biophysical models have been used largely in research settings by experts, it has also been used increasingly by clinical medical physicists over the last two decades. A good understanding of the potentials and limitations of the biophysical models and their intended use is critically important in the widespread use of these models. To facilitate meaningful and consistent use of biophysical models in brachytherapy, Task Group 267 (TG‐267) was formed jointly with the American Association of Physics in Medicine (AAPM) and The Groupe Européen de Curiethérapie and the European Society for Radiotherapy & Oncology (GEC‐ESTRO) to review the existing biophysical models, model parameters, and their use in selected brachytherapy modalities and to develop practice guidelines for clinical medical physicists regarding the selection, use, and interpretation of biophysical models. The report provides an overview of the clinical background and the rationale for the development of biophysical models in radiation oncology and, particularly, in brachytherapy; a summary of the results of literature review of the existing biophysical models that have been used in brachytherapy; a focused discussion of the applications of relevant biophysical models for five selected brachytherapy modalities; and the task group recommendations on the use, reporting, and implementation of biophysical models for brachytherapy treatment planning and evaluation. The report concludes with discussions on the challenges and opportunities in using biophysical models for brachytherapy and with an outlook for future developments [ABSTRACT FROM AUTHOR]

Use of magnetic resonance (MR) imaging in radiation therapy has increased substantially in recent years as more radiotherapy centers are having MR simulators installed, requesting more time on clinical diagnostic MR systems, or even treating with combination MR linear accelerator (MR‐linac) systems. With this increased use, to ensure the most accurate integration of images into radiotherapy (RT), RT immobilization devices and accessories must be able to be used safely in the MR environment and produce minimal perturbations. The determination of the safety profile and considerations often falls to the medical physicist or other support staff members who at a minimum should be a Level 2 personnel as per the ACR. The purpose of this guidance document will be to help guide the user in making determinations on MR Safety labeling (i.e., MR Safe, Conditional, or Unsafe) including standard testing, and verification of image quality, when using RT immobilization devices and accessories in an MR environment. [ABSTRACT FROM AUTHOR]

This article analytically reviews the character of Sofia Petrovna in the novel Sofia Petrovna (Lidia, Chukovskaya, 1967/1988) in the context of the police persecutions carried out by the Stalinist regime between 1935 and 1938 known as the Great Terror. This novel, written clandestinely during that period, recounts Sofia's struggle to find out the whereabouts of her son Kolia, arrested for no apparent reason; the sterile determination of this mother from Leningrad in the face of the monstrous Soviet bureaucracy and her own stigmatization as a relative of an enemy of the people, are factors that constitute not only the fictional plot of this work, but also the silenced chronicle of millions of Soviet women. martyred to the point of destitution or death by the judicial and police bodies of the USSR, including the author herself, who lost her husband, the physicist Matvei Bronstein, during the purges. [ABSTRACT FROM AUTHOR]