Cavity Radiation Research Articles

Dysphagia and Dysphonia After Head and Neck Cancer.

The purpose of this work is to synthesize the latest developments in diagnosis and management of acute and late dysphagia and dysphonia in oral cavity cancer. A literature search was conducted using PubMed, Web of Science, Embase and Google Scholar in May 2024 of articles published between 2021 and 2024. Keywords in the search terms included oral cavity cancer, dysphagia, dysphonia, deglutition, swallowing, voice, oral cavity cancer treatment, oral cavity radiation, chemotherapy, dysgeusia, xerostomia, swallow preservation. Twenty-seven pertinent studies fit the inclusion criteria. The most common dysphagic complaints following head and neck cancer are trismus, xerostomia, mucositis and dysphagia. Dysphonia, change in voice is reported by half of head and neck cancer survivors. Fibrosis and neuropathy following radiation therapy to the oral cavity, tongue, oropharynx and its surrounding structures is the most common etiology of post-treatment dysphonia. Oral cavity cancers cause speech and swallowing dysfunction due to both anatomic and post-treatment changes. These sequalae can be detrimental to the quality of life of the head and neck cancer survivor. For both dysphagia and dysphonia after head and neck cancer early speech and swallow therapy with a Speech Language Pathologist are essential to restoring and maintaining function.

A High Gain Circularly Polarized Slot Antenna Array for 5G Millimeter-Wave Applications

An air-filled substrate-integrated waveguide (AF-SIW) circularly polarized (CP) 1 × 8 mm wave antenna array is presented for fifth-generation (5G) applications. The presented slot antenna array consists of three layers of PCB and one layer of aluminum, which serve as the AF-SIW feeding network and the metal cavity radiation element, respectively. The CP characteristic is achieved by the use of an S-shaped aluminum radiation cavity on the top of the AF-SIW feeding network. The air-filled substrate-integrated waveguide technique is unitized to achieve high radiation efficiency. A wide input impedance bandwidth of 18.4% is obtained for the proposed antenna scheme, ranging from 34.5 GHz to 41.5 GHz, with a peak gain of 18 dBic. As for CP characteristic, the proposed antenna possesses a wide 3 dB axial ratio (AR) bandwidth, which is 16.4% (36.5 GHz to 43 GHz). The antenna scheme is fabricated and measured to verify the potential application as well as the promising performance. The measured results of the 1 × 8 antenna array shows that the wide AR as well as the input impedance are simultaneously achieved, which coincide well with the simulated results. Also, the measured results indicate that the proposed antenna scheme might be a good candidate for future mobile applications.

Quantum nature of reactivity modification in vibrational polariton chemistry.

In this work, we present a mixed quantum-classical open quantum system dynamics method for studying rate modifications of ground-state chemical reactions in an optical cavity under vibrational strong-coupling conditions. In this approach, the cavity radiation mode is treated classically with a mean-field nuclear force averaging over the remaining degrees of freedom, both within the system and the environment, which are handled quantum mechanically within the hierarchical equations of motion framework. Using this approach, we conduct a comparative analysis by juxtaposing the mixed quantum-classical results with fully quantum-mechanical simulations. After eliminating spurious peaks that can occur when not using the rigorous definition of the rate constant, we confirm the crucial role of the quantum nature of the cavity radiation mode in reproducing the resonant peak observed in the cavity frequency-dependent rate profile. In other words, it appears necessary to explicitly consider the quantized photonic states in studying reactivity modification in vibrational polariton chemistry (at least for the model systems studied in this work), as these phenomena stem from cavity-induced reaction pathways involving resonant energy exchanges between photons and molecular vibrational transitions.

Brain Metastasis in the Emergency Department: Epidemiology, Presentation, Investigations, and Management.

Brain metastases (BMs) are the most prevalent type of cerebral tumor, significantly affecting survival. In adults, lung cancer, breast cancer, and melanoma are the primary cancers associated with BMs. Symptoms often result from brain compression, and patients may present to the emergency department (ED) with life-threatening conditions. The goal of treatment of BMs is to maximize survival and quality of life by choosing the least toxic therapy. Surgical resection followed by cavity radiation or definitive stereotactic radiosurgery remains the standard approach, depending on the patient's condition. Conversely, whole brain radiation therapy is becoming more limited to cases with multiple inoperable BMs and is less frequently used for postoperative control. BMs often signal advanced systemic disease, and patients usually present to the ED with poorly controlled symptoms, justifying hospitalization. Over half of patients with BMs in the ED are admitted, making effective ED-based management a challenge. This article reviews the epidemiology, clinical manifestations, and current treatment options of patients with BMs. Additionally, it provides an overview of ED management and highlights the challenges faced in this setting. An improved understanding of the reasons for potentially avoidable hospitalizations in cancer patients with BMs is needed and could help emergency physicians distinguish patients who can be safely discharged from those who require observation or hospitalization.

Quantum Phase Transition in a Modified Jaynes-Cummings Model

We introduce a modified Jaynes-Cummings model with single-photon cavity radiation field but with the atomic system instead of exchanging a single photon as in the Jaynes-Cummings model, it exchanges instead a squeezed photon with squeezing parameter r. This allows us to interpolate between the Rabi model (r = ∞) and the Jaynes-Cummings model (r = 0) by varying r. The model exhibits a quantum phase transition. Accordingly, the quantum phase transition realized in the Rabi model, giving rise to superradiance, also occurs in the Jaynes-Cummings model.

Self-consistent and precise measurement of time-dependent radiative albedo of gold based on specially symmetrical triple-cavity Hohlraum

A self-consistent and precise method to determine the time-dependent radiative albedo, i.e., the ratio of the reemission flux to the incident flux, for an indirect-drive inertial confinement fusion Hohlraum wall material is proposed. A specially designed symmetrical triple-cavity gold Hohlraum is used to create approximately constant and near-equilibrium uniform radiation with a peak temperature of 160 eV. The incident flux at the secondary cavity waist is obtained from flux balance analysis and from the shock velocity of a standard sample. The results agree well owing to the symmetrical radiation in the secondary cavity. A self-consistent and precise time-dependent radiative albedo is deduced from the reliable reemission flux and the incident flux, and the result from the shock velocity is found to have a smaller uncertainty than that from the multi-angle flux balance analysis, and also to agree well with the result of a simulation using the HYADES opacity.

Cupric oxide photonic microcavities and their omnidirectional high-efficiency light-trapping characteristics

Cupric Oxide's black appearance hides interesting topographic structures and optical properties. This work examines the structure of thermally-grown cupric oxide and describes optical effects exhibited by surface layers of cupric oxide. It also highlights connections of surface optical properties with the intricate 3D micro and nanostructures that are formed on the surface during the oxidation process. These structures exist over several orders of magnitude in length we show that the CuO surface has a random microcavity structure that leads not only to strong photon trapping – giving CuO its black appearance – but also confers omnidirectional light absorption characteristics. This can benefit a number of applications – both active and passive. Our work also shows that CuO surfaces can be restructured by irradiation with a laser beam. Furthermore, it is shown that CuO surfaces can emit strong black body cavity radiation due to their high emissivity, which could throw light on interesting physical phenomena.

Turbulent natural convection coupled with surface radiation in tall cavities heated by a linear heat flux and cold isothermally

Turbulent natural convection coupled with surface radiation in tall cavities heated by a linear heat flux and cold isothermally

Numerical analysis of gray gas radiation effects on heat and mass transfer in an annular cavity

This study deals with a numerical investigation of coupled double diffusive natural-convection with thermal radiation in an annular cavity containing a gray gas mixture. The black vertical cylindrical walls are maintained at different temperatures and concentrations to create cooperating flows. The finite volume method (using the SIMPLER algorithm) is used to solve the governing equations and the discrete ordinate method (with S8 quadrature) to treat the radiative aspect of the problem. A parametric study illustrating the influence of the optical thickness and the ratio of buoyancy forces, on the flow field and heat and mass transfer for Reyleigh number equal to 5?106 and aspect ratio equal to 1, is performed. The numerical results show that gas radiation modifies the flow structure and the distribution of temperature and concentration in the cavity. The effect of permutation of boundary conditions, between the vertical walls, on heat and mass transfer is also considered. The thermal radiation reduces the total heat transfer in the annular space regardless of the configuration of the boundary conditions.

Design of transient front-end signal digitizer for x-ray detector in laser inertial confinement fusion facility.

In a laser inertial confinement fusion (ICF) facility, an x-ray diode (XRD) detector is mainly used for precise measurement of black cavity radiation flow. The rapid rising time of the XRD detector and the intricate radiation environment of the ICF facility have posed new requirements for the bandwidth and anti-interference performance of signal digitization technologies. The standards are tough for the current recording system to meet. In this paper, based on the anti-interference of digital signals in the radiation field of the ICF facility, we have designed an XRD detector specific transient front-end signal digitizer (TFSD). The digitizer may be put together for consistent shielding in the radiation field since its size matches that of the XRD detector. The test results show that the TFSD has a higher signal input bandwidth than the existing recording method, considerably reduces the effect of pulse radiation field on signal recording, and significantly boosts the accuracy of recording and diagnosis.

Spin Chaos of Exciton Polaritons in a Magnetic Field

The spin properties of exciton polaritons in a micropillar cavity placed in a static magnetic field and excited by a resonant light wave are studied theoretically. Owing to the Zeeman effect, a nonlinear polariton system has two branches of optical response that are characterized by opposite circular polarizations. An indirect mechanism of polarization reversal is predicted, according to which the current state of the system undergoes a transition to dynamical chaos, and then the alternative spin state is established spontaneously. Such spin switches, mediated by a chaotic stage, proceed in both directions near the same critical excitation amplitude, so that the sign of the circular polarization of the cavity radiation is directly determined by the intensity of the optical pump.

Effect of cavity radiation on aluminium hollow tubes and facade system subjected to fire

PurposeThis paper numerically investigates the effect of cavity radiation on the thermal response of hollow aluminium tubes and facade systems subjected to fire.Design/methodology/approachFinite element simulations were performed using ABAQUS 6.14. The accuracy of the numerical model was established through experimental and numerical results available in the literature. The proposed numerical model was utilised to study the effect of cavity radiation on the thermal response of aluminium hollow tubes and facade system. Different scenarios were considered to assess the applicability of the commonly used lumped capacitance heat transfer model.FindingsThe effects of cavity radiation were found to be significant for non-uniform fire exposure conditions. The maximum temperature of a hollow aluminium tube with 1-sided fire exposure was found to be 86% greater when cavity radiation was considered. Further, the time to attain critical temperature under non-uniform fire exposure, as calculated from the conventional lumped heat capacity heat transfer model, was non-conservative when compared to that predicted by the proposed simulation approach considering cavity radiation. A metal temperature of 550 °C was attained about 18 min earlier than what was calculated by the lumped heat capacitance model.Research limitations/implicationsThe present study will serve as a basis for the study of the effects of cavity radiation on the thermo-mechanical response of aluminium hollow tubes and facade systems. Such thermo-mechanical analyses will enable the study of the effects of cavity radiation on the failure mechanisms of facade systems.Practical implicationsCavity radiation was found to significantly affect the thermal response of hollow aluminium tubes and façade systems. In design processes, it is essential to consider the potential consequences of non-uniform heating situations, as they can have a significant impact on the temperature of structures. It was also shown that the use of lumped heat capacity heat transfer model in cases of non-uniform fire exposure is unsuitable for the thermal analysis of such systems.Originality/valueThis is the first detailed investigation of the effects of cavity radiation on the thermal response of aluminium tubes and façade systems for different fire exposure conditions.

Natural convection–thermal radiation interaction in a non-Newtonian nanofluid-filled square cavity with a conductive baffle

This research aims to investigate the combination of natural convection and surface and volumetric radiation in water-aluminum oxide nanofluid with non-Newtonian effects in a square cavity with a conductive baffle on its hot wall. The left wall is hot while the right one is cold. Moreover, the horizontal walls are insulated, and the internal walls are radiatively active. The mass, momentum, and energy conservation equations are solved numerically using the control-volume-based finite difference method and the SIMPLE algorithm considering the surface radiation for the interior surfaces of the cavity and volumetric radiation for the non-Newtonian nanofluid. The volumetric radiation term in the energy equation is approximated using the Rosseland method. The effect of the Rayleigh number (Ra), the power-law index, and the volumetric radiation parameter on the flow field and the heat transfer rate are investigated using the numerical analysis results. Based on the results, an increase in Ra and a decrease in the power-law index lead to a rise in the heat transfer rate at a constant radiation parameter. As the Ra rises in the range, the average Nusselt number increases to 10 times at n = 0.8. Moreover, a rise in the volumetric radiation parameter increases the radiative Nusselt number and decreases the convective Nusselt number in both shear thickening and shear thinning fluids, although it increases the overall Nu. Increasing the volumetric radiation parameter from 0 to 2 enhances the average Nusselt number by more than 2.5 times at Ra = 103 and less than 2 times at Ra = 105.

Spin Chaos of Exciton Polaritons in a Magnetic Field

The spin properties of exciton polaritons in a micropillar cavity placed in a static magnetic field and excited by a resonant light wave are studied theoretically. Owing to the Zeeman effect, a nonlinear polariton system has two branches of optical response that are characterized by opposite circular polarizations. An indirect mechanism of polarization reversal is predicted, according to which the current state of the system undergoes a transition to dynamical chaos, and then the alternative spin state is established spontaneously. Such spin switches, mediated by a chaotic stage, proceed in both directions near the same critical excitation amplitude, so that the sign of the circular polarization of the cavity radiation is directly determined by the intensity of the optical pump.

Thermal performance of cavities in 3DPC building façades

In the quest for sufficient and comfortable housing in South Africa, attention to building orientation and thermal transmittance principles has significantly improved thermal performance in local houses. Thermal simulation and monitoring of houses in the Joe Slovo Phase Three development in Cape Town confirms improved performance by solar radiation blockage and shading. This paper simulates the thermal performance of a housing unit in this development. The house was instrumented with thermocouples, and monitored from March to December 2013 by Sustainable Energy Africa in collaboration with the National Department of Human Settlements. Sustainable Energy Africa reported significant improvement when compared to a nearby traditional Reconstruction and Development Programme house that had been monitored during the same period. With the benefit of the monitored thermal data, complete drawings, and specification details of the Joe Slovo Phase Three unit, the current research modelled and calibrated a simulation model in DesignBuilder. DesignBuilder was selected given its accreditation status for Green Star Rating of buildings in South Africa. An additional motivation for investigating this unit was the availability of recorded weather data from the nearby Cape Town International Airport, captured in the DesignBuilder climate data base for 2013, which was assumed relevant in lieu of complete weather station data measured at the location of the housing unit. The study aimed to simulate the monitored temperatures in the house with acceptable agreement, and to investigate further potential improvement in occupant thermal comfort by alternative 3D-printed concrete walling developed by the authors. Systematic finite element analysis (FEA) iteratively solved cavity radiation and convection in wall cavities to calibrate thermal transmittance parameters for DesignBuilder. The FEA results acceptably simulated temperatures monitored in this physical wall experiment. The calibrated DesignBuilder model simulated the indoor temperatures of the monitored house with acceptable agreement, and predicted significant improvement in occupant thermal comfort if the walls were 3D-printed with a particular cross-sectional design.

Development of hybrid resonator antennas using elliptical cavity and microstrip patch radiator

This paper presents a few linearly polarized (LP) Hybrid Resonator Antennas (HRAs) using half mode SIW-based semi-elliptical cavity provide wideband capability. Considering the resonate modes of an elliptical cavity, field distribution and resonate frequency are studied at the dominant mode of operation using HFSS; the cavity is halved along its major and minor axis to create an aperture led to obtaining two HMSIW semi-elliptical cavity-based aperture antennas. A 50 Ω feed line is applied to stimulate the cavity and to facilitate compatibility with planar circuitry. To increase the impedance bandwidth, one and two patch radiators are added in front of the aperture to excite the TM010 mode of the patch. The proposed structures are simulated using HFSS software, and the antenna parameters are adjusted for maximum bandwidth. Two prototypes of the HRAs are implemented for verification. The proposed structures are tested, and the radiation characteristics are reported. The results show that one HRA offers 15% bandwidth with a peak gain of 6.8 dBi, whereas the other antenna offers 20% impedance bandwidth with a 7.2 dBi gain. The introduced HRAs are low profile providing attractive features, and are good candidate as a single antenna or as an element of array.

Meterscale Strong Coupling between Magnons and Photons.

We experimentally realize a meterscale strong coupling effect between magnons and photons at room temperature, with a coherent coupling of ∼20 m and a dissipative coupling of ∼7.6 m. To this end, we integrate a saturable gain into a microwave cavity and then couple this active cavity to a magnon mode via a long coaxial cable. The gain compensates for the cavity dissipation, but preserves the cavity radiation that mediates the indirect photon-magnon coupling. It thus enables the long-range strong photon-magnon coupling. With full access to traveling waves, we demonstrate a remote control of photon-magnon coupling by modulating the phase and amplitude of traveling waves, rather than reconfiguring subsystems themselves. Our method for realizing long-range strong coupling in cavity magnonics provides a general idea for other physical systems. Our experimental achievements may promote the construction of information networks based on cavity magnonics.

A macroscale heat transfer analysis of the build chamber in a commercial electron beam powder bed fusion (EB-PBF) additive manufacturing system during component fabrication

In this research, a 3D numerical thermal cavity radiation model was developed to predict the evolution of the macroscale thermal field within the build chamber of a commercial EB-PBF system. The model was applied to predict the evolution of the thermal field in a component during fabrication. A combination of quantitative and qualitative data extracted from an ARCAM Q20Plus machine was used to validate the model. The results indicate that the portion of heat transferred to the inner Heat Shield via cavity radiation was a strong function of the Start Plate’s temperature, reaching 88% of the total heat input at a peak temperature of ∼725 °C. Once validated, the thermal model was used to analyse heat transport within the build chamber during the fabrication of a component. The outcomes revealed variability in temperature within the hexagonal base, up to 118 °C, and the powder bed below the platform of 107 °C. Moreover, substantial temperature variations exceeding 200 °C were identified within the component, specifically between the hexagonal base and the platform.

Induced entanglement by three-level laser in an open cavity coupled to thermal reservoir

In this study, we have investigated the squeezing and entanglement characteristics of the light produced by three-level atoms available in an open cavity and pumped to the top level by electron bombardment at constant rate. We have obtained steady-state solutions to the quantum Langevin equations for the cavity mode operators and the equations of evolution for the expectation values of the atomic operators by employing the large-time approximation approach. The squeezing characteristics, entanglement amplification, and normalized second-order correlation function of the cavity radiation are discussed using the resulting steady-state solutions. We have seen that the light generated by the three-level laser is in a squeezed state, and the squeezing occurs in the minus quadrature. It so turns out that the maximum quadrature squeezing of the two-mode cavity light is 37.5% for n̄=0, 36.5% for n̄=0.01, and 35.5% for n̄=0.02 below the vacuum-state level. We have also established that the impact of the thermal reservoir process results in increases in the mean and variance of the photon number. Additionally, it is discovered that quadrature squeezing and entanglement are increased by the existence of spontaneous emission. This indicates that there are actually more photons fluctuating in the cavity. It is found that the squeezing and entanglement in the two-mode light are directly related. As a result, an increase in the degree of squeezing directly leads to an increase in the degree of entanglement and vice versa. This shows that, whenever there is squeezing in the two-mode light; an entanglement exists in the system.

Sound Radiation by a Cylindrical Open Cavity with a Surface Source at the Bottom

The rigorous solution describing the sound radiation by an arbitrary surface source located at the bottom of a cylindrical open cavity embedded in a flat baffle has been obtained. The open cavities of different shapes can be found in some architectural structures as well as are components of sensors, musical instruments and vehicles. The presented formulas have been expressed in the form of infinite sums. To use them, the infinite sums have to be truncated to the finite number of terms. Therefore, in practice, the results obtain based on the proposed solution are not exact and their accuracy is determined by the truncation error. The use of presented formulas is an alternative method for the finite element method (FEM). However, taking into account that the calculation efficiency of FEM rapidly decrease when a volume of considered region increases, the obtained in this study solution can be more useful in some practical cases. The approximated formula of a high computational efficiency has been presented for the sound pressure in the far field. The sound radiation has been analyzed for a rectangular piston as a sound source. The influence of cavity depth ratio on the radiation efficiency has been investigated. The cases for which the cavity radiation efficiency can be approximately calculated from the formula valid for a baffled sound source have been determined.