Miracle-dz/UniFAR-FTUs huggingface dataset:
Study of Classical and Quantum Open Systems

This thesis covers various aspects of open systems in classical and quantum mechanics. In the first part, we deal with classical systems. The bath-of-oscillators formalism is used to describe an open system, and the phenomenological Langevin equation is recovered. The Fokker-Planck equation is derived from its corresponding Langevin equation. The Fokker-Planck equation for a particle in a periodic potential in the high-friction limit is solved using the continued-fraction method. The equilibrium and time-dependent solutions are obtained. Under strong periodic driving, we observe significant non-linear effects in the dynamical hysteresis loops. Shapiro steps appear in the time-average of the drift velocity curves. Similar study is carried out for a dipole in an electric field. In the second part of the thesis, we begin the study of open quantum systems by re-deriving the quantum master equation using perturbation theory. The master equation is then applied to the bath-of-oscillators model. The subtleties and approximations of the master equation are discussed. We then use the master equation to solve the damped harmonic oscillator. The equilibrium solution coincides with the canonical distribution. The steady state response to DC and AC forces is also studied. Driven systems are more challenging in quantum open systems, and we manage to solve the quantum master equation with the continued-fraction method. We obtain the frequency-dependent susceptibility curves, which exhibit typical absorption and dispersion profiles.
Equilibrium spin pulsars unite neutron star populations

Many pulsars are formed with a binary companion from which they can accrete matter. Torque exerted by accreting matter can cause the pulsar spin to increase or decrease, and over long times, an equilibrium spin rate is achieved. Application of accretion theory to these systems provides a probe of the pulsar magnetic field. We compare the large number of recent torque measurements of accreting pulsars with a high-mass companion to the standard model for how accretion affects the pulsar spin period. We find that many long spin period (P > 100 s) pulsars must possess either extremely weak (B 10^14 G) magnetic fields. We argue that the strong-field solution is more compelling, in which case these pulsars are near spin equilibrium. Our results provide evidence for a fundamental link between pulsars with the slowest spin periods and strong magnetic fields around high-mass companions and pulsars with the fastest spin periods and weak fields around low-mass companions. The strong magnetic fields also connect our pulsars to magnetars and strong-field isolated radio/X-ray pulsars. The strong field and old age of our sources suggests their magnetic field penetrates into the superconducting core of the neutron star.
A nonlinear evolution equation for pulsating detonations using Fickett's model with chain branching kinetics

The detonation wave stability is addressed using Fickett's equation, i.e., the reactive form of Burgers' equation. This serves as a simple analogue to the reactive Euler equations, permitting one to gain insight into the nonlinear dynamics of detonation waves. Chemical kinetics were modeled using a two-step reaction with distinct induction and reaction zones. An evolution equation for the detonation structure was derived using the method of matched asymptotics for large activation energy and slow rate of energy release. While the first order solution was found unconditionally unstable, the second order evolution equation predicted both stable and unstable solutions. The neutral stability boundary was found analytically, given by $\chi=4$, where $\chi$ is the product of activation energy and the ratio of induction to reaction time. This reproduces accurately what has been previously established for the reactive Euler equations and verified experimentally. The evolution equation also captures stable limit cycle oscillations in the unstable regime and offers unique insight into the instability mechanism. The mechanism amplifying the perturbations lies within the induction zone, where the Arrhenius-type rate equation provides a large change in induction times for small perturbations. The mechanism attenuating the perturbations arises from acoustic effects, which delays the amplification of the shock front. The longer the detonation wave, the more time it takes for the amplification from the reaction zone to reach the shock front, creating gradients that counter-act the amplification from the flame acceleration. The results agree with direct numerical simulation, as well as recovering many similarities with the reactive Euler equation.
Development and Practical Application of a Psychological Skill Training Program for National Wheelchair Curling Players -Frontal EEG Asymmetry 향상을 위한

The present study aimed to develop a sports psychological skill training program and to test its applicability to improve the performance of national wheelchair curling players. A total of 4 participants completed the study. Subjects have been to 12 sessions of 6 different psychological skills training programs (routine training, attentional focus training, writing practice training in diary, relation training, self-control training, and positive self-talk training). The effectiveness of psychological skills training has been evaluated with 6 questionnaires and EEG measurement. The result was that psychological skills training had improved coping with adversity, peaking under pressure, and concentration, self-management and reduced anxiety of Korean national wheelchair curling player. The result was that the EEG inter-hemispheric asymmetry index showed negative emotional states before psychological skill training but positive emotional states after. The result implies that psychological skill training plays an important mediating role in bringing about positive effects in the psychological elements and competitiveness in national wheelchair curling players.
DARK ENERGY FROM THE LOG-TRANSFORMED CONVERGENCE FIELD

A logarithmic transform of the convergence field improves “the information content,” i.e., the overall precision associated with the measurement of the amplitude of the convergence power spectrum, by improving the covariance matrix properties. The translation of this improvement in the information content to that in cosmological parameters, such as those associated with dark energy, requires knowing the sensitivity of the log-transformed field to those cosmological parameters. In this paper, we use N-body simulations with ray tracing to generate convergence fields at multiple source redshifts as a function of cosmology. The gain in information associated with the log-transformed field does lead to tighter constraints on dark energy parameters, but only if shape noise is neglected. The presence of shape noise quickly diminishes the advantage of the log-mapping, more quickly than we would expect based on the information content. With or without shape noise, using a larger pixel size allows for a more efficient log-transformation.
Boundary-aware feature and prediction refinement for polyp segmentation

ABSTRACT Polyp segmentation from colonoscopy videos is an essential task in medical image processing for detecting early cancer. However, segmenting a precise boundary is still challenging, even with powerful deep neural networks. We consider the difficulty can be caused by: (1) the ambiguity boundary and (2) some complicated shape makes polyps hard to segment. To address these problems, we propose the Boundary-aware Feature and Prediction Refinement framework (BaFPR) for polyp segmentation. Specifically, we design a segmentation decoder for representation learning with boundary prior and propose a novel consistency loss to learn clues from the polar coordinate. The decoder mainly consists of a boundary prior module (BPM) and a bi-directional fusion module (BiFM). BPM is designed to learn the boundary prior, while BiFM learns to fuse representations of BPM and multi-scale representations from an encoder. To handle these complicated shapes of polyps, we maintain an extra segmentation network that learns with polar transformations of data to provide extra clues for the main segmentation network by our proposed consistency loss. We evaluated BaFPR with five challenging datasets for polyp segmentation and the results showed that our proposal consistently improves the segmentation performance of polyps. Code available at: https://github.com/MoriLabNU/BaFPR.
How Do Employees Perceive Digital Transformation and its Effects? A Theory of the Smart Machine Perspective

Digital transformation continues to profoundly impact employees in organizations in many industries. While past research has extensively investigated the impact of digital transformation on organizations, we still lack a comprehensive understanding of the factors that are relevant to examine how employees perceive digital transformation and its effects. One theory that explicitly has been built to account for a digital transformation in the past is the theory of the smart machine. To provide insights about relevant factors, we apply the theory of the smart machine and develop and evaluate an instrument to measure several of its key concepts for the first time. We build on established research guidelines to provide a 36-item survey instrument to measure the concepts Introduction of IT, Effects of automation, and Effects of informating. Finally, we provide implications for practice and further research.
Identification of crashworthiness indicators of column energy absorbers with triggers in the form of cylindrical embossing on the lateral edges using artificial neural networks with in the on the using

on the lateral edges were considered. These variants differ in the diameter of the trigger, its depth and position. The geometrical parameters of the trigger are crucial for the energy absorption performance of the energy absorber. The following indicators are studied: PCF (Peak Crushing Force), MCF (Mean Crushing Force), CLE (Crash Load Effi -ciency), SE (Stroke Efficiency) and TE (Total Efficiency). On the basis of numerical studies validated by experimentation, a neural network has been created with the aim of predicting the above-mentioned indices with an acceptable error for an energy absorber with the trigger of specified geometrical parameters and position. The paper demonstrates that the use of an effective multilayer perceptron can successfully speed up the design process, saving time on multivariate time-consuming analyses. Abstract The possibility of using artificial neural networks • to identify the most advantageous variants of column energy is shown The considered design variants differ in geometric • parameters and the position of the trigger The research was carried out with the use of FEM, • and the models were validated by the experiment It has been shown that the use of neural networks • to predict the properties of the energy absorber is possible with a slight error in relation to the time-consuming multi-variant FEM analyzes. indicators triggers of cylindrical
STABILITY OF MAGNETIZED DISKS AND IMPLICATIONS FOR PLANET FORMATION

This paper considers gravitational perturbations in geometrically thin disks with rotation curves dominated by a central object, but with substantial contributions from magnetic pressure and tension. The treatment is general, but the application is to the circumstellar disks that arise during the gravitational collapse phase of star formation. We find the dispersion relation for spiral density waves in these generalized disks and derive the stability criterion for axisymmetric (m = 0) disturbances (the analog of the Toomre parameter QT) for any radial distribution of the mass-to-flux ratio λ. The magnetic effects work in two opposing directions: on one hand, magnetic tension and pressure stabilize the disk against gravitational collapse and fragmentation; on the other hand, they also lower the rotation rate making the disk more unstable. For disks around young stars the first effect generally dominates, so that magnetic fields allow disks to be stable for higher surface densities and larger total masses. These results indicate that magnetic fields act to suppress the formation of giant planets through gravitational instability. Finally, even if gravitational instability can form a secondary body, it must lose an enormous amount of magnetic flux in order to become a planet; this latter requirement represents an additional constraint for planet formation via gravitational instability and places a lower limit on the electrical resistivity.
RESIDUAL ENERGY IN MAGNETOHYDRODYNAMIC TURBULENCE

There is mounting evidence in solar wind observations and in numerical simulations that kinetic and magnetic energies are not in equipartition in magnetohydrodynamic (MHD) turbulence. The origin of their mismatch, the residual energy Er = Ev − Eb, is not understood well. In the present work this effect is studied analytically in the regime of weak MHD turbulence. We find that residual energy is spontaneously generated by turbulent dynamics, and it has a negative sign, in good agreement with the observations. We find that the residual energy condenses around k‖ = 0 with its k‖-spectrum broadening linearly with k⊥, where k‖ and k⊥ are the wavenumbers parallel and perpendicular to the background magnetic field, and the field-perpendicular spectrum of the residual energy has the scaling Er(k⊥)∝k−1⊥ in the inertial interval. These results are found to be in agreement with numerical simulations. We propose that residual energy plays a fundamental role in Alfvénic turbulence and it should be taken into account for the correct interpretation of observational and numerical data.
A HYBRID MODEL FOR THE EVOLUTION OF GALAXIES AND ACTIVE GALACTIC NUCLEI IN THE INFRARED

We present a comprehensive investigation of the cosmological evolution of the luminosity function of galaxies and active galactic nuclei (AGNs) in the infrared (IR). Based on the observed dichotomy in the ages of stellar populations of early-type galaxies on one side and late-type galaxies on the other, the model interprets the epoch-dependent luminosity functions at z ⩾ 1.5 using a physical approach for the evolution of proto-spheroidal galaxies and of the associated AGNs, while IR galaxies at z < 1.5 are interpreted as being mostly late-type “cold” (normal) and “warm” (starburst) galaxies. As for proto-spheroids, in addition to the epoch-dependent luminosity functions of stellar and AGN components separately, we have worked out, for the first time, the evolving luminosity functions of these objects as a whole (stellar plus AGN component), taking into account in a self-consistent way the variation with galactic age of the global spectral energy distribution. The model provides a physical explanation for the observed positive evolution of both galaxies and AGNs up to z ≃ 2.5 and for the negative evolution at higher redshifts, for the sharp transition from Euclidean to extremely steep counts at (sub-)millimeter wavelengths, as well as the (sub-)millimeter counts of strongly lensed galaxies that are hard to account for by alternative, physical or phenomenological, approaches. The evolution of late-type galaxies and z < 1.5 AGNs is described using a parametric phenomenological approach. The modeled AGN contributions to the counts and to the cosmic infrared background (CIB) are always sub-dominant. They are maximal at mid-IR wavelengths: the contribution to the 15 and 24 μm counts reaches 20% above 10 and 2 mJy, respectively, while the contributions to the CIB are of 8.6% and of 8.1% at 15 μm and 24 μm, respectively. The model provides a good fit to the multi-wavelength (from the mid-IR to millimeter waves) data on luminosity functions at different redshifts and on number counts (both global and per redshift slices). A prediction of the present model, useful to test it, is a systematic variation with wavelength of the populations dominating the counts and the contributions to the CIB intensity. This implies a specific trend for cross-wavelength CIB power spectra, which is found to be in good agreement with the data.
GAS ACCRETION IS DOMINATED BY WARM IONIZED GAS IN MILKY WAY MASS GALAXIES AT z ∼ 0

We perform high-resolution hydrodynamic simulations of a Milky Way mass galaxy in a fully cosmological setting using the adaptive mesh refinement code, Enzo, and study the kinematics of gas in the simulated galactic halo. We find that the gas inflow occurs mostly along filamentary structures in the halo. The warm-hot (105 K 106 K) ionized gases are found to dominate the overall mass accretion in the system (with –5 M☉ yr−1) over a large range of distances, extending from the virial radius to the vicinity of the disk. Most of the inflowing gas (by mass) does not cool, and the small fraction that manages to cool does so primarily close to the galaxy (R ≲ 100 kpc, with more pronounced cooling at smaller R), perhaps comprising the neutral gas that may be detectable as, e.g., high-velocity clouds. The neutral clouds are embedded within larger, accreting filamentary flows, and represent only a small fraction of the total mass inflow rate. The inflowing gas has relatively low metallicity (Z/Z☉ < 0.2). The outer layers of the filamentary inflows are heated due to compression as they approach the disk. In addition to the inflow, we find high-velocity, metal-enriched outflows of hot gas driven by supernova feedback. Our results are consistent with observations of halo gas at low z.
Comparing a large number of multivariate distributions

In this paper, we propose a test for the equality of multiple distributions based on kernel mean embeddings. Our framework provides a flexible way to handle multivariate or even high-dimensional data by virtue of kernel methods and allows the number of distributions to increase with the sample size. This is in contrast to previous studies that have been mostly restricted to classical low-dimensional settings with a fixed number of distributions. By building on Cramer-type moderate deviation for degenerate two-sample V-statistics, we derive the limiting null distribution of the test statistic and show that it converges to a Gumbel distribution. The limiting distribution, however, depends on an infinite number of nuisance parameters, which makes it infeasible for use in practice. To address this issue, the proposed test is implemented via the permutation procedure and is shown to be minimax rate optimal against sparse alternatives. During our analysis, an exponential concentration inequality for the permuted test statistic is developed which may be of independent interest.
The role of nuclear activity as the power source of ultraluminous infrared galaxies

We present the results of a 5–8 μm spectral analysis performed on the largest sample of local ultraluminous infrared galaxies (ULIRGs) selected so far, consisting of 164 objects up to a redshift of ∼0.35. The unprecedented sensitivity of the Infrared Spectrograph onboard Spitzer allowed us to develop an effective diagnostic method to quantify the active galactic nucleus (AGN) and starburst (SB) contribution to this class of objects. The large AGN over SB brightness ratio at 5–8 μm and the sharp difference between the spectral properties of AGN and SB galaxies in this wavelength range make it possible to detect even faint or obscured nuclear activity, and disentangle its emission from that of star formation. By defining a simple model we are also able to estimate the intrinsic bolometric corrections for both the AGN and SB components, and obtain the relative AGN/SB contribution to the total luminosity of each source. Our main results are the following. 1 The AGN detection rate among local ULIRGs amounts up to 70 per cent, with 113/164 convincing detections within our sample, while the global AGN/SB power balance is ∼1/3. 2 A general agreement is found with optical classification; however, among the objects with no spectral signatures of nuclear activity, our IR diagnostics find a subclass of elusive, highly obscured AGN. 3 We analyse the correlation between nuclear activity and IR luminosity, recovering the well-known trend of growing AGN significance as a function of the overall energy output of the system: the sources exclusively powered by star formation are mainly found at LIR < 1012.3 L⊙, while the average AGN contribution rises from ∼10 to ∼60 per cent across the ULIRG luminosity range. 4 From a morphological point of view, we confirm that the AGN content is larger in compact systems, but the link between activity and evolutionary stage is rather loose. 5 By analysing a control sample of IR-luminous galaxies around z∼ 1, we find evidence for only minor changes with redshift of the large-scale spectral properties of the AGN and SB components. This underlines the potential of our method as a straightforward and quantitative AGN/SB diagnostic tool for ULIRG-like systems at high redshift as well, and hints to possible photometric variants for fainter sources.
Black hole mergers: do gas discs lead to spin alignment?

In this Letter, we revisit arguments suggesting that the Bardeen–Petterson effect can coalign the spins of a central supermassive black hole binary accreting from a circumbinary (or circumnuclear) gas disc. We improve on previous estimates by adding the dependence on system parameters and noting that the non-linear nature of warp propagation in a thin viscous disc affects alignment. This reduces the disc’s ability to communicate the warp, and can severely reduce the effectiveness of disc-assisted spin alignment. We test our predictions with a Monte Carlo realization of random misalignments and accretion rates, and we find that the outcome depends strongly on the spin magnitude. We estimate a generous upper limit to the probability of alignment by making assumptions which favour it throughout. Even with these assumptions, about 40 per cent of black holes with a 0.5 do not have time to align with the disc. If the residual misalignment is not small and it is maintained down to the final coalescence phase, this can give a powerful recoil velocity to the merged hole. Highly spinning black holes are thus more likely being subject to strong recoils, the occurrence of which is currently debated.
Diode-pumped high-power continuous-wave intracavity frequency-doubled Pr3+:YLF ultraviolet lasers around 349 nm

Abstract High-power continuous-wave ultraviolet lasers are useful for many applications. As ultraviolet laser sources, the wavelength switching capability and compact structure are very important to extend the applicability and improve the flexibility in practical applications. In this work, we present two simple and relatively compact schemes by laser diode pumping to obtain a watt-level single-wavelength 348.7-nm laser and discrete wavelength tunable ultraviolet lasers around 349 nm (from 334.7 to 364.5 nm) by intracavity frequency doubling based on Pr3+:YLF and $\unicode{x3b2}$ -BBO crystals. The maximum output power of the single-wavelength 348.7-nm laser is 1.033 W. The output powers of the discrete wavelength tunable lasers are at the level of tens of milliwatts, except for two peaks at 348.7 and 360.3 nm with output powers of approximately 500 mW. In addition, simulations are carried out to explain the experimental results and clarify the tuning mechanisms.