resonance

摘要： The Purcell effect is commonly used to increase the spontaneous emission rate by modifying the local environment of a light emitter.Here,we propose a silicon dielectric cuboid nanoantenna for simultaneously enhancing electric dipole(ED),magnetic dipole(MD)and electric quadrupole(EQ)emission.We study the scattering cross section,polarization charge distribution,and electromagnetic field distribution for electromagnetic plane wave illuminating the silicon dielectric cuboid nanoantenna,from which we have identified simultaneous existence of ED,MD and EQ resonance modes in this nanoantenna.We have calculated the Purcell factor of ED,MD and EQ emitters with different moment orientations as a function of radiation wavelength by placing these point radiation source within the nanoantenna,respectively.We find that the resonances wavelengths of the Purcell factor spectrum are matching with the resonance modes in the nanoan-tenna.Moreover,the maximum Purcell factor of these ED,MD and EQ emitters is 18,150 and 118 respectively,occur-ring at the resonance wavelength of 475,750,and 562 nm,respectively,all within the visible range.The polarization charge distribution features allow us to clarify the excitation and radiation of these resonance modes as the physical ori-gin of large Purcell factor simultaneously occurring in this silicon cuboid nanoantenna.Our theoretical results might help to deeply explore and design the dielectric nanoantenna as an ideal candidate to enhance ED,MD and EQ emission simultaneously with very small loss in the visible range,which is superior than the more popular scheme of plasmonic nanoantenna.

摘要： Homeostasis creates self-organized synchrony of the body’s reactions, and despite the energetically open system with intensive external and internal interactions, it is robustly stable. Importantly the self-organized system has scaling behaviors in its allometry, internal structures, and dynamic processes. The system works stochastically. Deterministic reductionism has validity only by the great average of the probabilistic processes. The system’s dynamics have a characteristic distribution of signals, which may be characterized by their frequency distribution, creating a particular “noise” 1/f of the power density. The stochastic processes produce resonances pumped by various noise spectra. The chemical processes are mostly driven by enzymatic processes, which also have noise-dependent resonant optimizing. The resonance frequencies are as many as many enzymatic reactions exist in the target.

摘要： Superconducting linear accelerators(SCL)have a high acceleration gradient and are capable of operating in a high-duty factor mode.For high-power and high-intensity SCL,the design of beam dynamics generally follows the principle that the zero-current periodic phase advance(σ0)of each degree of freedom is less than 90°to avoid envelope instability caused by space charge.However,this principle is obtained under the condition of a completely periodic focusing channel,and it is ambiguous for pseudoperiodic structures,such as linear accelerators.Although transverse beam dynamics without acceleration have been studied by other researchers,it appears that there are some connections between pure 2D and 3D beam dynamics.Based on these two points,five focusing schemes for the solenoid and quadrupole doublet channels were designed to simulate the beam behavior with non-constantσ0.Among them,the four schemes follow the characteristics of variation in the zero-current longitudinal phase advance(σ0l)under a constant acceleration gradient and synchronous phase.The zero-current transverse phase advance(σ0t)is consistent withσ0l,based on the equipartition requirement.The initialσ0twas set to 120°,110°,100°,and 90°,and was then gradually decreased to approximately 40°at the end of the channel.The last scheme maintains the maximumσ0tof88°by reducing the acceleration gradient of the corresponding cavities,until the point at whichσ0tequals88°with a normal gradient.Using the stopbands obtained from the linearized envelope equations and multiparticle particle-in-cell(PIC)simulations,the transport properties of both continuous and 3D-bunched beams with the acceleration of the five focusing schemes were studied.It was found that for a CW beam,when tune depression>0.7,σ0tcan break through 90°when the beams were transported in both solenoid and quadrupole doublet periodic focusing channels.When tune depression<0.7,the conclusions were different.For the solenoid focusing system,σ0tcan partially break through 90°,and the beam quality is not significantly affected.For the quadrupole doublet focusing system,a partial breakthrough of 90°has a greater impact on the beam quality.The same conclusions were obtained for a bunched beam with acceleration.

摘要： It is important to look at the behaviour of a living system from the point of view of the biophysical paradigm. In fact, the chemical reactions, which allow us to understand how metabolic processes take place, are short-range and they are activated at a distance of one atomic or molecular diameter. 100,000 reactions/sec. take place in a cell, perfectly balanced in space and time, i.e. these happen at the right time and in the right place. So, it is chemically inexplicable how this can be possible, because it is absolutely necessary that molecules recognize each other at distances greater than a molecular diameter. The biophysical paradigm, through coherent resonance mechanisms, tries to explain how molecules can recognize each other “from afar”. It is a matter of beginning to understand that, probably, the same atoms and molecules are endowed with a kind of “intrinsic intelligence” that guides them in their interactions, and the key to understanding can only be of physical type. We can also hypothesize that a cellular information mechanism based on endogenous electromagnetic fields exists. In this way, DNA could play a role of in-out antenna, due to its double helix shape (resonant LC circuit). This paper speaks about these unexpected, but not too many, connections between Physics and Biology.

摘要： Sloshing is relevant in several applications like ship tanks,space and automotive industry and seiching in harbours.Due to the relationship between ship and sloshing motions and possibility of structural damage,it is important to represent this phenomenon accurately.This paper investigates sloshing at shallow liquid depths in a rectangular container using experiments and RANS simulations.Free and forced sloshing,with and without baffles,are studied at frequencies chosen specifically in proximity to the first mode natural frequency.The numerically calculated free surface elevation is in close agreement with observations from experiments.The upper limit of the resonance zone,sloshing under different filling depths and roll amplitudes and sloshing with one,two and four baffles are also investigated.The results show that the extent of the resonance zone is reduced for higher filling depth and roll amplitude.It is also found that the inclusion of baffles moves the frequency at which the maximum free surface elevation occurs,away from the fundamental frequency.Finally,a submerged baffle is found to dissipate more energy compared to a surface piercing baffle and that the effect of several submerged baffles is similar to that of a single submerged baffle.

摘要： Many applications of metasurfaces require an ability to dynamically change their properties in the time domain. Electrical tuning techniques are of particular interest, since they pave a way to on-chip integration of metasurfaces with optoelectronic devices.In this work, we propose and experimentally demonstrate an electro-optic lithium niobate(EO-LN) metasurface that shows dynamic modulations to phase retardation of transmitted light. Quasi-bound states in the continuum(QBIC) are observed from this metasurface. By applying external electric voltages, the refractive index of lithium niobate(LN) is changed by Pockels EO nonlinearity, leading to efficient phase modulations to the transmitted light around the QBIC wavelength. The EO-LN metasurface developed in this study opens up new routes for potential applications in the field of displaying, pulse shaping, and spatial light modulating.

摘要： High-magnetic-field nuclear magnetic resonance(NMR)has manifested itself as an indispensable tool in modern scientific research in the fields of physics,chemistry,materials science,biology,and medicine,among others,owing to its great advantages in both measurement sensitivity and quantum controllability.At present,the use of pulsed fields is the only controllable and nondestructive way to generate high magnetic fields of up to 100 T.NMRcombined with pulsed fields is therefore considered to have immense potential for application in multiple scientific and technical disciplines.Irrespective of the paramount technical challenges,including short duration of the pulsed fields,unstable plateaus,and poor field homogeneity and reproducibility,great progress has been made in a number of pulsed-field laboratories in Germany,France,and Japan.In this paper,we briefly review the status of the pulsed-field NMR technique,as well as its applications in multiple disciplines.We also discuss future trends with regard to the upgrading of pulsed-field NMR.

摘要： Today is a happy day for the community of magnetic resonance since it marks the birthday of the very first issue of Magnetic Resonance Letters(MRL),a new journal aiming to promote the multidisciplinary area.

摘要： Structural and dielectric properties of Ce-doped BaTi_(0.97)Y_(0.03)O_(3)powders,with the chemical formulation(Ba_(1−x)Ce_(x))(Ti(_(0.97−x/4))-Y_(0.03))O_(3)such as x=0%,1%,3%,5%,7%and 9%,produced by the sol-gel method,have been investigated.X-ray diffraction analysis showed that Ce^(3+)ions incorporated Ba sites until x=7%indicating that this concentration represents a solubility limit of Ce^(3+)ions in BaTi_(0.97)Y_(0.03)O_(3)matrix.Scanning electron microscopy(SEM)analysis showed a decrease in grain size down to the same concentration of 7%.Raman spectroscopy analysis showed the appearance of A_(1g) mode,which we attributed to the effect of incorporation of Ce^(3+)and Y^(3+)in BaTiO_(3)matrix.Dielectric measurements revealed that doping with cerium lowers the temperature of permittivity maximum at the ferroelectric-to-paraelectric transition(FPT)of the BaTi_(0.97)Y_(0.03)O_(3)sample,and reaches a value that should be below 40°C for x=9%.Moreover,the phenomenon of dielectric resonance was observed on all Ce-doped samples,which was not the case with other dopants as reported in the literature.

摘要： BACKGROUND Postoperative liver failure is the most severe complication in cirrhotic patients with hepatocellular carcinoma(HCC) after major hepatectomy. Current available clinical indexes predicting postoperative residual liver function are not sufficiently accurate.AIM To determine a radiomics model based on preoperative gadoxetic acid-enhanced magnetic resonance imaging for predicting liver failure in cirrhotic patients with HCC after major hepatectomy.METHODS For this retrospective study, a radiomics-based model was developed based on preoperative hepatobiliary phase gadoxetic acid-enhanced magnetic resonance images in 101 patients with HCC between June 2012 and June 2018. Sixty-one radiomic features were extracted from hepatobiliary phase images and selected by the least absolute shrinkage and selection operator method to construct a radiomics signature. A clinical prediction model, and radiomics-based model incorporating significant clinical indexes and radiomics signature were built using multivariable logistic regression analysis. The integrated radiomics-based model was presented as a radiomics nomogram. The performances of clinical prediction model, radiomics signature, and radiomics-based model for predicting post-operative liver failure were determined using receiver operating characteristics curve, calibration curve, and decision curve analyses.RESULTS Five radiomics features from hepatobiliary phase images were selected to construct the radiomics signature. The clinical prediction model, radiomics signature, and radiomics-based model incorporating indocyanine green clearance rate at 15 min and radiomics signature showed favorable performance for predicting postoperative liver failure(area under the curve: 0.809-0.894). The radiomics-based model achieved the highest performance for predicting liver failure(area under the curve: 0.894;95%CI: 0.823-0.964). The integrated discrimination improvement analysis showed a significant improvement in the accuracy of liver failure prediction when radiomics signature was added to the clinical prediction model(integrated discrimination improvement = 0.117, P =0.002). The calibration curve and an insignificant Hosmer-Lemeshow test statistic(P = 0.841) demonstrated good calibration of the radiomics-based model. The decision curve analysis showed that patients would benefit more from a radiomics-based prediction model than from a clinical prediction model and radiomics signature alone.CONCLUSION A radiomics-based model of preoperative gadoxetic acid–enhanced MRI can be used to predict liver failure in cirrhotic patients with HCC after major hepatectomy.

摘要： 为了提高在测量较高频率时的磁共振设备的灵敏度，射频发射一测量线圈（１０．３０）分成可以激励和可以输出的两个对称的绕组（３２，３４）。绕组中心接头的相互连接，可以利用平衡不平衡转换器（５４）。但其他对称的耦合器件，例如，高频变压器（７０），或合适的同轴电缆（６０，６２）也可以使用。