S. Lee

Although valence electrons are clearly delocalized in molecular bonding frameworks, chemists and physicists have long debated the question of whether the core vacancy created in a homonuclear diatomic molecule by absorption of a single x-ray photon is localized on one atom or delocalized over both. We have been able to clarify this question with an experiment that uses Auger electron angular emission patterns from molecular nitrogen after inner-shell ionization as an ultrafast probe of hole localization. The experiment, along with the accompanying theory, shows that observation of symmetry breaking (localization) or preservation (delocalization) depends on how the quantum entangled Bell state created by Auger decay is detected by the measurement.

Journal Article On pointwise convergence of the solutions to Schrödinger equations in ℛ2 Get access Sanghyuk Lee Sanghyuk Lee School of Mathematical Sciences, Seoul National UniversitySeoul 151-742, South Korea E-mail address: shlee@math.snu.ac.kr Search for other works by this author on: Oxford Academic Google Scholar International Mathematics Research Notices, Volume 2006, 2006, 32597, https://doi.org/10.1155/IMRN/2006/32597 Published: 01 January 2006 Article history Published: 01 January 2006 Received: 16 August 2006 Revision received: 11 October 2006 Accepted: 22 October 2006

The concept of using short plasma sections several meters in length to double the energy of a linear collider just before the collision point is proposed and modeled. In this scenario the beams from each side of a linear collider are split into pairs of microbunches with the first driving a plasma wake that accelerates the second. The luminosity of the doubled collider is maintained by employing plasma lenses to reduce the spot size before collision.

We investigate photo-double-ionization of ${\mathrm{H}}_{2}$ by circular polarized photons at $h\ensuremath{\nu}=160\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. The previously observed two-center interference pattern in the angular distribution of the electron sum momentum is shown to depend strongly on the internuclear distance and the summed electron momenta.

Molecular chirality is represented as broken mirror symmetry in the structural orientation of constituent atoms and plays a pivotal role at every scale of nature. Since the discovery of the chiroptic property of chiral molecules, the characterization of molecular chirality is important in the fields of biology, physics, and chemistry. Over the centuries, the field of optical chiral sensing was based on chiral light–matter interactions between chiral molecules and polarized light. Starting from simple optics-based sensing, the utilization of plasmonic materials that could control local chiral light–matter interactions by squeezing light into molecules successfully facilitated chiral sensing into noninvasive, ultrasensitive, and accurate detection. In this Review, the importance of plasmonic materials and their engineering in chiral sensing are discussed based on the principle of chiral light–matter interactions and the theory of optical chirality and chiral perturbation; thus, this Review can serve as a milestone for the proper design and utilization of plasmonic nanostructures for improved chiral sensing.

Aim: The World Falls Guidelines (WFG) Task Force published a falls risk stratification algorithm in 2022. However, its adaptability is uncertain in low- and middle-income settings such as Malaysia due to different risk factors and limited resources. We evaluated the effectiveness of the WFG risk stratification algorithm in predicting falls among community-dwelling older adults in Malaysia.Methods: Data from the Malaysian Elders Longitudinal Research subset of the Transforming Cognitive Frailty into Later-Life Self-Sufficiency cohort study was utilized. From 2013-2015, participants aged ≥55 years were selected from the electoral rolls of three parliamentary constituencies in Klang Valley. Risk categorization used baseline data. Falls prediction values were determined using follow-up data from wave 2 (2015-2016), wave 3 (2019) and wave 4 (2020-2022).Results: Of 1,548 individuals recruited, 737 were interviewed at wave 2, 858 at wave 3, and 752 at wave 4. Falls were reported by 13.4%, 29.8% and 42.9% of the low-, intermediate- and high-risk groups at wave 2, 19.4%, 25.5% and 32.8% at wave 3, and 25.8%, 27.7% and 27.0% at wave 4, respectively. At wave 2, the algorithm generated a sensitivity of 51.3% (95%CI, 43.1-59.2) and specificity of 80.1% (95%CI, 76.6-83.2). At wave 3, sensitivity was 29.4% (95%CI, 23.1-36.6) and specificity was 81.6% (95%CI, 78.5-84.5). At wave 4, sensitivity was 26.0% (95%CI, 20.2-32.8) and specificity was 78.4% (95%CI, 74.7-81.8).Conclusion: The algorithm has high specificity and low sensitivity in predicting falls, with decreasing sensitivity over time. Therefore, regular reassessments should be made to identify individuals at risk of falling.

Results of the most sophisticated measurements in coincidence with the angular-resolved $K$-shell photoelectrons and Auger electrons and with two atomic ions produced by dissociation of ${\mathrm{N}}_{2}$ molecule are analyzed. Detection of photoelectrons at certain angles makes it possible to separate the Auger decay processes of the $1{\ensuremath{\sigma}}_{g}$ and $1{\ensuremath{\sigma}}_{u}$ core-hole states. The Auger electron angular distributions for each of these hole states are measured as a function of the kinetic-energy release of two atomic ions and are compared with the corresponding theoretical angular distributions. From that comparison one can disentangle the contributions of different repulsive doubly charged molecular ion states to the Auger decay. Different kinetic-energy-release values are directly related to the different internuclear distances. In this way one can trace experimentally the behavior of the potential energy curves of dicationic final states inside the Frank-Condon region. Presentation of the Auger-electron angular distributions as a function of kinetic-energy release of two atomic ions opens a new dimension in the study of Auger decay.

Theoretical two-center interference patterns produced (i) by the $K$-shell photoionization process of the ${\mathrm{N}}_{2}$ molecule and (ii) by the Auger decay process of the $K$-shell hole state of the ${\mathrm{N}}_{2}$ molecule are compared for the case of equal photo- and Auger-electron energies of about 360 eV. The comparison shows that both the angular distribution of the photoelectrons and the angular distribution of the Auger electrons of equal energy in the molecular frame are primarily defined by the Young interference. The experimental data for the angular resolved $K$-shell Auger electrons as a function of the kinetic-energy release (KER) obtained earlier [Phys. Rev. A 81, 043426 (2010)] have been renormalized in order to visualize the angular variation in the regions of low Auger-electron intensities. That renormalized data are compared with the corresponding theoretical results. From the known behavior of the potential energy curves, the connection between the KER and the internuclear distance can be established. Since the Young interference pattern is sensitive to the internuclear distance in the molecule, from the measured KER dependence of the Young interference pattern one can trace the behavior of the Auger-electron angular distribution for different molecular terms as a function of internuclear distance. The results of that analysis are in a good agreement with the corresponding theoretical predictions.

We report a kinematically complete experiment of carbon $1s$ photoionization of ${\text{CO}}_{2}$ including Auger decay and fragmentation. By measuring in coincidence of ${\text{CO}}_{2}$ $\text{C}(1s)$ photoelectrons and ion fragments using synchrotron light at several energies above the $\text{C}(1s)$ threshold, we determine photoelectron angular distributions as well as Auger-electron angular distributions with full solid angle in the molecular fixed frame. We confirm recent unexpected results showing an asymmetry of the photoelectron angular distribution along the molecular axis after ionization of the $\text{C}(1s)$ orbital. Our high statistics and high resolution measurement unveils asymmetric features in the photoelectron angular distribution which change as a function of the kinetic energy release. This finding provides strong evidence that varying C--O bondlengths are the main cause for these asymmetries. The Auger-electron angular distributions do not show strong correlation with the photoelectrons.

The Auger transitions to different repulsive doubly charged molecular ion states are separated by measuring the angular resolved photoelectrons and Auger electrons in coincidence in the molecular fixed frame. The separation is achieved by comparing the experimental Auger-electron angular distributions at different kinetic-energy release values with theoretical curves calculated for different final dicationic states.

We report the characterization of the forced damped harmonic oscillations of 133 Cs atoms in a magneto-optical trap, which was realized by modulating the intensity of the lasers counterpropagating along the anti-Helmholtz coil axis. Trap parameters such as trap frequency, damping coefficient, and magnitude of the driving force were determined from the resonant vibrational amplitude of the 133 Cs atomic cloud depending on the modulation frequency of the modulated laser intensity. The experimental results were compared with the theoretical ones based on the simple two-level and multi-level atom models, considering all possible transition lines used to trap the 133 Cs atom, and were found to be consistent with their theoretical counterparts. Furthermore, we theoretically examined the effect of the repumping laser on trap parameters.

We present a comprehensive description of the processes contributing to the electron capture/emission by bulk oxide traps, which allows for interpretation of RTS and 1/f noise data and extraction of the trap characteristics. It is shown that the electron capture/emission times could be controlled by the trap structural relaxation (caused by the trapped electrons) rather than by the electron tunneling to/from the trap as generally assumed. The extracted model parameters, in particular, relaxation energy, allow identifying defect nature.

We consider the mass concentration phenomenon for the L 2-critical nonlinear Schrödinger equations. We show the mass concentration of blow-up solutions contained in space near the finite time. The new ingredient in this paper is a refinement of Strichartz's estimates with the mixed norm for 2 < q ≤ r.

In this paper, MEMS devices for TPMS and exhaust monitoring of automobiles are investigated. To counteract to EURO6 regulation, particulate matter sensor for detecting DPF failure of diesel engine as well as accelerometers for calibrating centrifugal effect on pressure measurement and secondary energy harvesting device will have strong effect for car safety. Heater embedded PM sensor uses electro dynamic principle and achieves resolution of 0.25mg/km. The accelerometer for TPMS application focuses on simplicity and low cost using piezoresistive beams and anodic bonding. Electrostatic energy harvester uses only 3 masks and shows symmetrical output of up to 0.73uW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> .

In this paper, the mechanical and electrical characteristics of 3D microelectrode are presented to provide the long-term stability of the implanted microelectrode. As the dimensions of the microelectrode become smaller, the microelectrode can be easily damaged by mechanical pressure and over-injected electric charge. In order to avoid these destructions, allowable mechanical and electrical stress should be determined. Experiments for durability evaluation are set up and performed to measure the mechanical force and safe charge injection limit. The result of the experiments shows that the allowable mechanical force in vertical and horizontal direction is 0.8165 N and 0.2068 N, respectively. In the charge injection test, it is observed that the density of injected charge is a prior factor in microelectrode dissolution rather than the total amount of injected charge.

The radiation patterns of sound from a baffled, oscillating piston are studied via a numerical method. To investigate the effects of discontinuous boundary condition on the sound radiation from a piston, we introduce three piston models that have, respectively, definite characteristics at their own edges. Linearized Euler's equations in Cartesian co-ordinates are solved by the dispersion relation preserving finite difference scheme. The numerical results are compared with the analytic results derived from the Kirchhoff–Helmholtz integral theorem. Through the comparison of numerical results of each boundary condition, we find that discontinuity at the edge of the piston as well as the Helmholtz number of the vibrating piston is an important factor in determining the sound radiation pattern of the piston. The validity of numerical simulation for discontinuity effects is confirmed by comparison of the numerical and analytic results.

Learning and selecting important points on a point cloud is crucial for point cloud understanding in various applications. Most of early methods selected the important points on 3D shapes by analyzing the intrinsic geometric properties of every single shape, which fails to capture the importance of points that distinguishes a shape from objects of other classes, i.e., the distinction of points. To address this problem, we propose D-Net (Distinctive Network) to learn for distinctive point clouds based on a self-attentive point searching and a learnable feature fusion. Specifically, in the self-attentive point searching, we first learn the distinction score for each point to reveal the distinction distribution of the point cloud. After ranking the learned distinction scores, we group a point cloud into a high distinctive point set and a low distinctive one to enrich the fine-grained point cloud structure. To generate a compact feature representation for each distinctive point set, a stacked self-gated convolution is proposed to extract the distinctive features. Finally, we further introduce a learnable feature fusion mechanism to aggregate multiple distinctive features into a global point cloud representation in a channel-wise aggregation manner. The results also show that the learned distinction distribution of a point cloud is highly consistent with objects of the same class and different from objects of other classes. Extensive experiments on public datasets, including ModelNet and ShapeNet part dataset, demonstrate the ability to learn for distinctive point clouds, which helps to achieve the state-of-the-art performance in some shape understanding applications.

Recent studies on image super-resolution make use of Generative Adversarial Networks to generate the high-resolution image counterpart of the low-resolution input. However, while being able to generate sharp high-resolution images, Generative Adversarial Networks based super-resolution methods often fail to produce good results when tested on images having different degradation as the low-resolution images used in the training. Some recent works have tried to mitigate this failure by introducing a degradation network that can replicate the noise of real-world low-resolution images. However, even these methods can produce poor results if a real-world test image differs much from the real-world images in the training data set. This paper proposes the use of adversarial losses on the feature maps extracted by a pre-trained network with the generated high-resolution image as input. This is in contrast to all other Generative Adversarial Networks-based super-resolution methods that directly apply the adversarial loss to the generated high-resolution image. The rationale behind this idea is illustrated, and experimental results confirm that high-resolution images generated by the proposed method achieve better results in both quantitative and qualitative evaluations than methods that directly apply adversarial losses to generated high-resolution images.

A combined Computational Fluid Dynamics (CFD)–Kirchoff method is presented for predicting high-speed impulsive noise generated by a rotor in hover. Two types of Kirchoff integral formulas are used: one of them is a classical linear Kirchoff formulation and the other a non-linear Kirchoff formulation. An Euler finite-difference solver is executed first, from which a flow field is obtained to be used as an input to the Kirchoff formulation to predict the acoustic far-field. The calculations are performed at Mach numbers of 0·90 and 0·95 to investigate the effectiveness of the linear and non-linear Kirchoff formulas for delocalized flow. During these calculations, the retarded time equation is also carefully examined, in particular, for the cases where a control surface is located outside the sonic cylinder, for which multiple roots are obtained. Predicted results of acoustic far-field with the linear Kirchoff formulation agree well with the experimental data when the control surface is at a particular location (Rcs/R=1·46), but the correlation weakens as it moves away from this specific location of the control surface due to the delocalized non-linear aerodynamic flow field. Calculations based on the non-linear Kirchoff equation using the sonic cylinders as the control surfaces show reasonable agreements with the experimental data in the negative amplitudes for both tip Mach numbers of 0·90 and 0·95, except for some computational integration problems over a shock. It can be concluded that a non-linear formulation is necessary if the control surface is close to the blade and the flow is delocalized.

Solar prominences are relatively dense objects suspended in the hot and tenuous solar corona. It has long been speculated that prominence material is supported against gravity by the Lorentz force exerted by magnetic field whose line of force is locally concave upward forming a so-called ‘dip’. However, there has been no clear supporting observation mainly due to difficulty in determining 3D magnetic fields within prominences. We present a high-resolution Hα observation of a prominence in which time series of the filtergrams along with Dopplergrams reveals an oscillatory motion of the cool material along a concave upward magnetic dip structure across the main body of the prominence. The observed magnetic dip is an important clue to our understanding of the physics of solar prominences.

Linear theory for phonon scattering by discrete breathers in the discrete nonlinear Schroedinger equation using the transfer matrix approach is presented. Transmission and reflection coefficients are obtained as a function of the wave vector of the input phonon. The occurrence of a nonzero transmission, which in fact becomes perfect for a symmetric breather, is shown to be connected with localized eigenmodes thresholds. In the weak-coupling limit, perfect reflection are shown to exist, which requires two scattering channels. A necessary condition for a system to have a perfect reflection is also considered in a general context.

This paper describes the theoretical and experimental analy!is used to evaluate the performance of rolling piston type compressor. Thermodynamic properties of refrigerant in compression chamber are theoretically analysed using simple thermodynamic model which consists of 3-step processes that are adiabatic compression process, isochoric heat transfer process and leakage process. Also based upon this model, the coefficients of heat transfer for compression process are obtained by experimental results of a specially installed test compressor. INTRODUCTION Generally two approaches have been used for the performance analys_is of rotary compressors and modeling the thermodynamic behavior of the working fluid. One is polytropic process model and the other is the 1st law of thermodynamics model. In order to see the internal gas properties in compression chamber, it is necessary to study kinematic motion of compressor, leakage with oil flow and heat transfer etc .. But it is difficult to calculate its properties by theoretical analysis. In case of the polytropic process model with constant polytropic index n , some deviations occur between computation and corresponding experiment. Some experimental investigations show that polytropic index n varies with rotating angle of rolling piston, operating condition and geometry of compressor. It is too complicated to model and calculate the influence of several parameters on compression process and to do parametric study on its factors. So to gain a better description of the thermodynamic behavior of rotary compressors, many models about heat transfer during the compression process have been presented by applying the lst law of themodynamics. In most of these papers, the heat transfer model was made by an assumption, that is, heat transfer was proportional to the product of heat transfer area and temperature difference between cylinder wall and gas. But it is difficult and complex to evaluate a proper heat transfer coefficient according to the boundary condition such as oil film and leakage and to describe the accurate situation of compression chamber under the operation. The purpose of this paper is to present a model which can describe the compression process including the heat transfer, leakage and geometric effect of inner cylinder. In this model, real compression process is assumed to be divided into three simple independent processes. The first step of this model is adiabatic compression process with no heat transfer and no leakage. The second step is heat transfer process from/to cylinder wall with no volume change and no leakage. The last step is leakage process