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Management of Conditions Associated With Aging and Older Adults Using Therapeutic Electromagnetic Energy
摘要： To assess the effectiveness of therapeutic electromagnetic energy in the management of conditions associated with an aging and older adult population. A systematic review of literature from 2008 to 2018 was completed in PubMed, CINAHL, and Science Direct. We also reviewed sources to identify additional relevant studies. Studies in this review were limited to randomized controlled trials that evaluated the effects of shortwave diathermy or pulsed electromagnetic energy units in treating conditions commonly experienced by adults older than 50 years. Study quality was determined using the Physiotherapy Evidence Database (PEDro) classification scale. Fifteen randomized controlled trials met our search criteria. Multiple pathologies were evaluated with the studies examining treatment effects of knee osteoarthritis (n = 12), frozen shoulder (n = 1), postoperative rotator cuff repair (n = 1), and postmenopausal osteoporosis (n = 1). Of the 12 studies that examined knee osteoarthritis, 2 compared pulsed electromagnetic field to placebo or sham, 2 compared the addition of shortwave diathermy to strengthening activities alone, 3 evaluated shortwave diathermy dosage, 3 compared shortwave diathermy to other modalities, and 2 reviewed the benefits of adding pulsed electromagnetic field to other modalities and exercise. Due to the high degree of variability in protocols and outcome measures among studies, meta-analysis was not appropriate. Studies on knee osteoarthritis reported that the use of pulsed electromagnetic field and shortwave diathermy provides statistically significant improvement in pain and function compared with placebo, sham, or control, although there appears to be no benefit in using either form of electromagnetic radiation in addition to or in place of another modality. It also appears that dosage does not significantly change short-term outcomes. These findings are similar to those identified in other recently published systematic reviews that focused exclusively on knee osteoarthritis. Subjects with shoulder pathologies showed improvements in pain, mobility (range of motion), function, activities of daily living, and pain medication usage with pulsed electromagnetic field or shortwave diathermy. Changes in postmenopausal bone density were similar when pulsed electromagnetic field was compared with medication. Conclusion: Shortwave diathermy and pulsed electromagnetic frequency demonstrate similar clinical benefits as other modalities for improving pain, function, and quality of life in the short-term. Further research is needed to better evaluate the parameters of electromagnetic energy and effects for other conditions commonly affecting aging and older adults and at other treatment sites on the body.
关键词： diathermy,electromagnetic energy,pulsed electromagnetic field,shortwave diathermy
更新于2025-09-23 15:23:52
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Non-Markovian evolution of a two-level system interacting with a fluctuating classical field via dipole interaction
摘要： We address memory effects in the dynamics of a two-level open quantum system interacting with a classical fluctuating field via dipole interaction. In particular, we study the backflow of information for a field with a Lorentzian spectrum, and reveal the existence of two working regimes, where memory effects are governed either by the energy gap of the two-level system, or by the interaction energy. Our results show that non-Markovianity increases with time, at variance with the results obtained for dephasing, and in spite of the dissipative nature of the interaction, thus suggesting that the corresponding memory effects might be observed in practical scenarios.
关键词： stochastic electromagnetic field,memory effects,non-Markovianity
更新于2025-09-23 15:23:52
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Two-state switchable plasmonic tweezers for dynamic manipulation of nano-objects
摘要： In this work, we present a plasmonic platform capable of trapping nano-objects in two different spatial configurations. The switch between the two trapping states, localized on the tip and on the outer wall of a vertical gold nanochannel, can be activated by varying the focusing position of the excitation laser along the main axis of the nanotube. We show that the switching of trapping site is induced by changes in the distribution of the electromagnetic field and of the trapping force. The 'inner' and 'outer' trapping states are characterized by a static and a dynamic behavior respectively, and their stiffness is measured by analyzing the positions of the trapped specimens as a function of time. In addition, we demonstrate that the stiffness of the static state is high enough to trap particles with diameter as small as 40 nm. These results show a simple, controllable way to generate a switchable two-state trapping regime, which could be used as a model for the study of dynamic trapping or as a mechanism for the development of nanofluidic devices.
关键词： gold nanochannel,nano-objects,plasmonic platform,trapping force,nanofluidic devices,electromagnetic field,dynamic behavior,trapping states
更新于2025-09-23 15:21:01
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Nonlinear Optics || Wave-Equation Description of Nonlinear Optical Interactions
摘要： We have seen in the last chapter how nonlinearity in the response of a material system to an intense laser field can cause the polarization of the medium to develop new frequency components not present in the incident radiation field. These new frequency components of the nonlinear polarization act as sources of new frequency components of the electromagnetic field. In the present chapter, we examine how Maxwell’s equations describe the generation of these new components, and more generally we see how the various frequency components of the field become coupled by the nonlinear interaction.
关键词： wave equation,electromagnetic field,frequency components,Maxwell’s equations,nonlinear optics,polarization
更新于2025-09-23 15:21:01
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Metallic Core-Shell Photonic Crystals for Surface-Enhanced Raman Scattering (SERS)
摘要： Metallic core-shell substrate is specially used to serve ultrasensitive molecular detection down to concentration of micromolar level based on surface-enhanced Raman spectroscopy (SERS). Calculations show that the amorphous poly(methyl methacrylate) (PMMA) photonic crystals incorporated with metal nanoparticles which is either gold or silver nanoparticles can significantly increase the electromagnetic fields at the air dielectric interface, leading to remarkable Raman enhancement. Corresponding experiments and characterizations show the characteristic and performance of core-shell structures which present an excellent sensitivity, reproducibility and stability to act as SERS substrate.
关键词： Silver nanoparticles,Electromagnetic field,Poly(methyl methacrylate),SERS,Gold nanoparticles,Core-shell
更新于2025-09-23 15:19:57
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Defining the Work Done on an Electromagnetic Field
摘要： The problem of defining work done on an electromagnetic field (EMF) via moving charges does not have a ready solution, because the standard Hamiltonian of an EMF—whose time derivative should define the work according to the first law—is not gauge invariant. This limits applications of statistical mechanics to an EMF. We obtained a new, explicitly gauge-invariant Hamiltonian for an EMF that depends only on physical observables. This Hamiltonian allows us to define work and to formulate the second law for an EMF. It also leads to a direct link between this law and the electrodynamic arrow of time, i.e., choosing retarded, and not advanced solutions of wave equations. Measuring the thermodynamic work can determine whether the photon mass is small but nonzero.
关键词： photon mass,work,second law,Hamiltonian,electromagnetic field,gauge invariance,electrodynamic arrow of time
更新于2025-09-23 15:19:57
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Quantum Coherence Behaviors for a Uniformly Accelerated Atom Immersed in Fluctuating Vacuum Electromagnetic Field with a Boundary
摘要： We investigate the dynamics of quantum coherence (QC) for a uniformly accelerated atom interacting with fluctuating electromagnetic field subject to a conductor boundary. We firstly derive the master equation that the atom evolution obeys. We find that without boundary, QC declines under the effect of Unruh thermal bath and vacuum fluctuation. However, with a boundary, the degradation, fluctuation, and preservation of QC are closely related to boundary effect, atomic polarization, and acceleration. Furthermore, in the presence of a boundary, QC can effectively be protected under the influence of the vacuum fluctuation and Unruh thermal effect when the atom is transversely polarizable and near this boundary, and the presence of boundary gives us more freedom of controlling the QC behaviors.
关键词： Dynamics,Unruh effect,Electromagnetic field,Quantum coherence
更新于2025-09-19 17:15:36
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Ehrenfest+R dynamics. I. A mixed quantum–classical electrodynamics simulation of spontaneous emission
摘要： The dynamics of an electronic system interacting with an electromagnetic field is investigated within mixed quantum–classical theory. Beyond the classical path approximation (where we ignore all feedback from the electronic system on the photon field), we consider all electron–photon interactions explicitly according to Ehrenfest (i.e., mean-field) dynamics and a set of coupled Maxwell–Liouville equations. Because Ehrenfest dynamics cannot capture certain quantum features of the photon field correctly, we propose a new Ehrenfest+R method that can recover (by construction) spontaneous emission while also distinguishing between electromagnetic fluctuations and coherent emission.
关键词： quantum electrodynamics,electromagnetic field,Ehrenfest dynamics,spontaneous emission,mixed quantum-classical theory
更新于2025-09-19 17:15:36
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Plasmonic Nanoparticle Film for Low-Power NIR-Enhanced Photocatalytic Reaction
摘要： Plasmonic metal nanostructures offer the unique ability to effectively enhance sunlight harvesting by localized surface plasmon resonance (LSPR), which can induce direct photocatalytic reactions. However, only metal nanoparticles with a relatively low magnitude of electromagnetic field enhancement usually require a high illumination intensity to ensure the catalytic performance, which greatly limits the solar photocatalytic efficiency. Herein, we designed plasmonic Au nanoparticle film with high electromagnetic field enhancement to achieve high-efficiency catalytic activity under low power NIR light illumination. This work minimized the influence of the photothermal effect on the reaction by using a low illumination intensity and further revealed the main contribution of plasmon-excited hot electrons to the photochemical reaction. This study provides important insights into the study of the mechanism of LSPR in photocatalytic reactions and further improves the efficiency of solar energy utilization.
关键词： Localized surface plasmon resonance,hot electrons,low power illumination,electromagnetic field enhancement,NIR photocatalysis
更新于2025-09-19 17:13:59
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Unidirectional and robust propagating surface magnetoplasmon in magneto-optical coaxial waveguides
摘要： In this paper, a novel coaxial waveguide constituted by a hollow cylinder made of a magneto-optical material and a metal wire at the axis is proposed. The surface magnetoplasmon and guided modes of the waveguide are studied. The results show that the dispersion relation and electromagnetic field distribution are highly sensitive to the operating frequency and physical dimensions of the structure. It is demonstrated that there exist three different types of modes, that is bulk-mode, surface mode, and regular mode. By adjusting the operating frequency and reducing the inner diameter of the hollow cylinder, the regular mode is suppressed and only the surface mode remains, which shows one-way propagating property. Moreover, the one-way surface mode is robust against backscattering at defect and surface roughness, which has a good potential in practice. The unique properties of this waveguide are demonstrated through mode analyses as well as numerical simulations.
关键词： electromagnetic field distribution,dispersion relation,surface magnetoplasmon,one-way propagation,magneto-optical coaxial waveguides
更新于2025-09-19 17:13:59