Potential Problems Research Articles

Inverse problem in energy-dependent potentials using semiclassical methods

Wave equations with energy-dependent potentials appear in many areas of physics, ranging from nuclear physics to black hole perturbation theory. In this work, we use the semiclassical Wentzel-Kramers-Brillouin (WKB) method to first revisit the computation of bound states of potential wells and reflection/transmission coefficients in terms of the Bohr-Sommerfeld rule and the Gamow formula. We then discuss the inverse problem, in which the latter observables are used as a starting point to reconstruct the properties of the potentials. By extending known inversion techniques to energy-dependent potentials, we demonstrate that so-called width-equivalent or WKB-equivalent potentials are not isospectral anymore. Instead, we explicitly demonstrate that constructing quasi-isospectral potentials with the inverse techniques is still possible. Those reconstructed, energy-independent potentials share key properties with the width-equivalent potentials. We report that including energy-dependent terms allows for a rich phenomenology, particularly for the energy-independent equivalent potentials. Published by the American Physical Society 2024

Revisiting O(N) σ model at unphysical pion masses and high temperatures

Roy-equation analysis on lattice data of ππ scattering phase shifts at mπ=391 MeV reveals that the lowest f0 meson becomes a bound state under this condition. In addition, there is a pair of complex poles below threshold generated by crossing symmetry [X.-H. Cao , ]. We use the N/D method to partially recover crossing symmetry of the O(N) σ model amplitude at leading order of 1/N expansion, and qualitatively reproduce the pole structure and pole trajectories with varying pion masses as revealed by Roy-equation analyses. The σ pole trajectory with varying temperature is also discussed and found to be similar to its properties when varying mπ. As the temperature increases, the complex σ poles firstly move from the second Riemann sheet to the real axis becoming two virtual state poles, and then one virtual state pole moves to the first sheet turning into a bound state pole and finally tends to the pion pole position at high temperature which is as expected from the chiral symmetry restoration. Our results provide further evidence that the lowest f0 state extracted from experiments and lattice data plays the role of the σ meson in the spontaneous breaking of chiral symmetry. Finally, we also briefly discuss the problems of the effective potential in the situation when mπ and the temperature become large. Published by the American Physical Society 2024

Determination of the Energy Eigenvalues of the Varshni-Hellmann Potential

In this paper, we solve the bound state problem for the Varshni-Hellmann potential via a useful technique. In our technique, we obtain the bound state solution of the Schrödinger equation for the Varshni-Hellmann potential via ansatz method. We obtain the energy eigenvalues and the corresponding eigenfunctions. Also, the behavior of the energy spectra for both the ground and the excited state of the two body systems is illustrated graphically. The similarity of our results to the accurate numerical values is indicative of the efficiency of our technique.

Accounting and silence: The unspeakable, the unsaid, and the inaudible

AbstractThis paper studies accounting and silence. Building on studies of accounting talk and introducing theories of “silencing,” we highlight the role of accounting silences in the production of engaging organizational conversations. Through a qualitative case study, we identify three forms of silence—the unspeakable, the unsaid, and the inaudible—and their links to accounting. Silences create motivations to engage in further accounting talk, but they also deny certain groups a voice in those conversations. An impression of participation, openness, and transparency emerges despite unequal access and the silencing of certain groups. Accounting itself can be silenced to avoid uncomfortable topics, potential problems, and anxiety‐inducing uncertainties. This silencing may serve to preserve a useful ignorance, avoid being in the know, and build alluring narratives and engaging conversations. Accounting silences sustain such conversations by protecting them from alternative voices, unsettling knowledge, and narratives that are incompatible with the organization's preferred story.

Binary Graph Convolutional Network With Capacity Exploration.

The current success of Graph Neural Networks (GNNs) usually relies on loading the entire attributed graph for processing, which may not be satisfied with limited memory resources, especially when the attributed graph is large. This paper pioneers to propose a Binary Graph Convolutional Network (Bi-GCN), which binarizes both the network parameters and input node attributes and exploits binary operations instead of floating-point matrix multiplications for network compression and acceleration. Meanwhile, we also propose a new gradient approximation based back-propagation method to properly train our Bi-GCN. According to the theoretical analysis, our Bi-GCN can reduce the memory consumption by an average of ∼31x for both the network parameters and input data, and accelerate the inference speed by an average of ∼51x, on three citation networks, i.e., Cora, PubMed, and CiteSeer. Besides, we introduce a general approach to generalize our binarization method to other variants of GNNs, and achieve similar efficiencies. Although the proposed Bi-GCN and Bi-GNNs are simple yet efficient, these compressed networks may also possess a potential capacity problem, i.e., they may not have enough storage capacity to learn adequate representations for specific tasks. To tackle this capacity problem, an Entropy Cover Hypothesis is proposed to predict the lower bound of the width of Bi-GNN hidden layers. Extensive experiments have demonstrated that our Bi-GCN and Bi-GNNs can give comparable performances to the corresponding full-precision baselines on seven node classification datasets and verified the effectiveness of our Entropy Cover Hypothesis for solving the capacity problem.

Consistency, precision, and accuracy assessment of the collocation boundary element method for two-dimensional problems of potential and elasticity

Consistency, precision, and accuracy assessment of the collocation boundary element method for two-dimensional problems of potential and elasticity

Approaching certain central-field Schrödinger problems through the harmonic oscillator green's function

We propose a method to analytically solve the Schrödinger equation with central potentials. By means of Sturm–Liouville expansion, the Green's function (GF) of the Schrödinger differential operator can be represented in the GF of the isotropic harmonic oscillator. Applying this straightforward approach, we solve the Schrödinger problem for the Coulomb potential, for the Morse potential, and for the respective inverted potentials. Using the obtained results, we formulate a method to analytically solve Schrodinger equations for multi-well potentials, demonstrating that classically forbidden regions can be treated as inverted harmonic oscillators, whereas harmonic oscillators or Morse potentials can approximate the wells.

Regulating Autonomy in Civilian Drones: Towards a Spectral Approach

AbstractCivilian drones are becoming more functionally independent from human involvement which sets them on a path towards “autonomous” status. When defining “autonomy,” the European Union (EU) regulations, among other jurisdictions, employ an all-or-nothing approach, according to which a drone is either able to operate fully autonomously or not at all. This dichotomous approach disregards the various levels of drone autonomy and fails to capture the complexity of civilian drone operation. Within the EU, this has regulatory implications, such as regulatory lag, hindrance in better safety regulation, and incoherence with the Union’s regulatory approach towards Artificial Intelligence (AI). This article argues that understanding autonomy as a spectrum, rather than in a dichotomous way, would be more coherent with the technical functioning of drone and would avoid potential regulatory problems caused by the current dichotomous approach. In delineating this spectral approach, this article (1) analyses manifestations of autonomy in drone operations, (2) delineates efforts in the technical literatures and drone standardization to conceptualize “autonomy”, and (3) explores definitional attempts for autonomy made in three other technologies: self-driving cars, autonomous weapon systems, and autonomous maritime ships.

A Numerical Study of Quantum Entropy and Information in the Wigner-Fokker-Planck Equation for Open Quantum Systems.

Kinetic theory provides modeling of open quantum systems subject to Markovian noise via the Wigner-Fokker-Planck equation, which is an alternate of the Lindblad master equation setting, having the advantage of great physical intuition as it is the quantum equivalent of the classical phase space description. We perform a numerical inspection of the Wehrl entropy for the benchmark problem of a harmonic potential, since the existence of a steady state and its analytical formula have been proven theoretically in this case. When there is friction in the noise terms, no theoretical results on the monotonicity of absolute entropy are available. We provide numerical results of the time evolution of the entropy in the case with friction using a stochastic (Euler-Maruyama-based Monte Carlo) numerical solver. For all the chosen initial conditions studied (all of them Gaussian states), up to the inherent numerical error of the method, one cannot disregard the possibility of monotonic behavior even in the case under study, where the noise includes friction terms.

Measuring health-related quality of life in children with suspected genetic conditions: validation of the PedsQL proxy-report versions.

Measuring health-related quality of life (HRQoL) of children with suspected genetic conditions is important for understanding the effect of interventions such as genomic sequencing (GS). The Pediatric Quality of Life Inventory (PedsQL) is a widely used generic measure of HRQoL in pediatric patients, but its psychometric properties have not yet been evaluated in children undergoing diagnostic GS. In this cross-sectional study, we surveyed caregivers at the time of their child's enrollment into GS research studies as part of the Clinical Sequencing Evidence Generating Research (CSER)consortium. To evaluate structural validity of the PedsQL 4.0 Generic Core Scales and PedsQL Infant Scales parent proxy-report versions, we performed a confirmatory factor analysis of the hypothesized factor structure. To evaluate convergent validity, we examined correlations between caregivers' reports of their child's health, assessed using the EQ VAS, and PedsQL scores by child age. We conducted linear regression analyses to examine whether age moderated the association between caregiver-reported child health and PedsQL scores. We assessed reliability using Cronbach's alpha. We analyzed data for 766 patients across all PedsQL age group versions (1-12months through 13-18years). Model fit failed to meet criteria for good fit, even after modification. Neither age group (categorical) nor age (continuous) significantly moderated associations between PedsQL scores and caregiver-reported child health. Cronbach's alphas indicated satisfactory internal consistency for most PedsQL scales. The PedsQL Generic Core Scales and Infant Scales may be appropriate to measure HRQoL in pediatric patients with suspected genetic conditions across a wide age range. While we found evidence of acceptable internal consistency and preliminary convergent validity in this sample, there were some potential problems with structural validity and reliability that require further attention.

A dual-reciprocity boundary element method based transient seepage model with nonlinear distributed point source dual-porosity gas reservoir

As a result of advancements in gas reservoir development technologies and a deeper understanding of seepage theory, numerous nonlinear seepage problems have emerged. Consequently, conventional analytical solution models are no longer applicable. Moreover, existing semi-analytical and numerical solution models suffer from issues like high computational complexity and limited flexibility, significantly constraining their practical utility. For this purpose, a gas reservoir transient seepage model is established based on the dual-reciprocity boundary element method (DRBEM). This model couples the wellbore storage coefficients with skin factor and introduces a novel dual-porosity transient interporosity seepage algorithm, enabling the resolution of transient seepage problems in dual-porosity gas reservoirs with nonlinear point source distributions. Additionally, it investigates the dynamic behavior of bottomhole pressure during the early production stage of gas wells, while capturing the dynamic pressure distribution within the seepage field. This approach offers the advantages of semi-analyticity, meshless, and eliminates the need for Laplace transforms, resulting in a significant reduction in computational complexity. Ultimately, the application of our model to well-pattern production with the production system transition issues, in conjunction with the log-log type curves of bottomhole pressure, and the dynamics of gas reservoir pressure, enables the analysis of interference characteristics between injection-production wells. This showcases the practical advantages of the model's application. The findings of this study provide valuable assistance for modeling and solving transient seepage problems in dual-porosity oil and gas reservoirs production. The application of DRBEM in unsteady-state diffusion, heat conduction, stress fields, and other potential field problems is relevant for reference.

Optimal inverse problems of potentials for two given eigenvalues of Sturm–Liouville problems

The present paper is concerned with the infimum of the norm of potentials for Sturm–Liouville eigenvalue problems with Dirichlet boundary condition such that the first two eigenvalues are known. The explicit quantity of the infimum is given by the two eigenvalues.

Three-Dimension Calculation for the Scattering Problem for Non-Spherical Potential

The interaction of the 238U with a neutron is studied. Correct accounting for the non-spherical shape of the uranium nucleus is in focus. The optical potential is used as a model. It is shown that the spherically symmetric and non-spherical potentials give different scattering patterns, in particular different resonance features of the cross-section. The possibility of using the method as an extension of the particle–rotor model of the nucleus is illustrated.

Inverse Resonance Problems for Energy-Dependent Potentials on the Half-Line

Inverse Resonance Problems for Energy-Dependent Potentials on the Half-Line

A global study on knowledge and perception of HPV and HPV vaccination among young obstetricians and gynecologists.

Our goal is to improve the understanding of human papillomavirus (HPV) and its vaccination among obstetrics and gynecology trainees and young specialists worldwide. This cross-sectional study was conducted through an online survey consisting of 28 questions by the World Association of Trainees in Obstetrics and Gynecology between February and August 2023. The questionnaire collected demographic data of the study participants and assessed the respondents' knowledge and perception of HPV, HPV vaccines, and vaccine dosing schedule. Two hundred five Ob/Gyn trainees and young Ob/Gyns from 52 countries completed the survey. The majority of respondents were trainees (158, 77.1%). Most trainees and young Ob/Gyns learned about HPV for the first time during medical school (149, 72.6%). Almost all (204, 99.5%) Ob/Gyns responded that HPV was sexually transmitted. More than half of the respondents had not received HPV vaccination (110, 53.7%). The vaccine was recommended for respondents mostly by their Ob/Gyn senior colleagues (110, 53.7%). Most of the respondents knew how to manage HPV-positive patients (179, 87.3%). This study suggests that even though knowledge on HPV and its vaccination is satisfactory among trainees and young Ob/Gyns, HPV vaccination remains deficient. There is a need to understand, educate, and address the potential problem that lies underneath.

Exact tunneling solutions in multi-field potentials

The tunneling potential formalism makes it easy to construct exact solutions to the vacuum decay problem in potentials with multiple fields. While some exact solutions for single-field decays were known, we present the first nontrivial analytic examples with two and three scalar fields, and show how the method can be generalized to include gravitational corrections. Our results illuminate some analytic properties of the tunneling potential functions and can have a number of uses, among others: to serve as simple approximations to realistic potentials; to learn about parametric dependencies of decay rates; to check conjectures on vacuum decay; as benchmarks for multi-field numerical codes; or to study holographic interpretations of vacuum decay.

Symptom-specific improvement across therapies and their putative mediators: A mediation network intervention analysis

Objective We evaluated differential treatment effects on specific symptoms and their mediators for Cognitive Behavioral Analysis System of Psychotherapy (CBASP) and Supportive Psychotherapy (SP) in persistently depressed patients. Method We conducted a Bayesian mediation network intervention analysis with data from a randomized controlled trial comparing CBASP and SP. Three networks were calculated to investigate (1) differential treatment effects on specific symptoms, (2) differential treatment effects on the potential mediators interpersonal problems and social functioning, and (3) associations between change in symptoms and change in the potential mediators. Results First, we found no evidence that CBASP more strongly improves most depressive symptoms specifically, except minimal evidence of symptom-specific effects on sleeping problems and self-esteem. Second, no and minimal evidence for differential treatment effects on interpersonal problems and social functioning was shown, respectively. Third, interpersonal problems and social functioning were strongly related to depressive symptoms. Conclusion While CBASP showed superior treatment effects for overall symptom severity, this treatment might not be superior in improving specific symptoms and the potential mediators interpersonal problems and social functioning. Still, interpersonal problems and social functioning seem to play an important role for depression symptoms. Future research needs to further investigate potential working mechanisms of CBASP. Trial registration: ClinicalTrials.gov identifier: NCT00970437

Historical defects in buildings – No. 5: Wood-wool formwork

In this latest note, Hugh Docherty discusses the use of wood-wool slabs as permanent formwork to reinforced concrete slabs and the potential problems that can arise in this form of construction.

Effects of topographical disturbances on flexural wave motion in a viscous fluid

Main causes of ground disturbances are geological events such as earthquakes, underwater gravity mass flows, volcanic eruptions, and bottom explosions. This paper investigates the effects of transitory ground disturbance on the generation of flexural waves in the presence of a thin floating elastic plate. The problem is formulated using the Stokes stream function and wave potential boundary value problems in a viscous fluid. The expression of the plate deflection is obtained as multiple infinite integrals using the Fourier and Laplace transforms, which is further solved by the steepest descent method. Three types of ground disturbances such as H0(x)=e(−x2/2), H0(x)=e−|x|, and H0(x)=δ(x) are considered. The deflection of the floating elastic plate is investigated in connection to ground disturbances, fluid viscosity, and structural parameters such as mass per unit length of the plate and flexural rigidity. The study reveals that with higher viscosity and flexural rigidity, the amplitude of the plate deflection is reduced. Moreover, these two parameters play a great role in the reduction of plate deflection.

Perturbing masses: A study of centered co-circular central configurations in power-law n-body problems

This research investigates centered co-circular central configurations in the general power-law potential n-body problem. Firstly, there are no centered co-circular central configurations exist when precisely n−2 of the masses are equal; secondly, unless all masses are equal, no such configurations exist when masses can be divided into two sets of equal masses; thirdly, no such configurations exist when masses is a mix of equal masses and some heavier (lighter) ones, arranged such that the heavier (lighter) ones are non-adjacent.