Emission Amplitude Research Articles

Adiabatic control of decoherence-free subspaces in an open collective system

We propose a method to adiabatically control an atomic ensemble using a decoherence-free subspace (DFS) within a dissipative cavity. We can engineer a specific eigenstate of the system's Lindblad jump operators by injecting a field into the cavity which deconstructively interferes with the emission amplitude of the ensemble. In contrast to previous adiabatic DFS proposals, our scheme creates a DFS in the presence of collective decoherence. We therefore have the ability to engineer states that have high multiparticle entanglements which may be exploited for quantum information science or metrology. We further demonstrate a more optimized driving scheme that utilizes the knowledge of possible diabatic evolution gained from the so-called adiabatic criteria. This allows us to evolve to a desired state with exceptionally high fidelity on a timescale that does not depend on the number of atoms in the ensemble. By engineering the DFS eigenstate adiabatically, our method allows for faster state preparation than previous schemes that rely on damping into a desired state solely using dissipation.

Investigation of passive acoustic emissions during powder mixing in a V-blender

Powder mixing is a complex process and a critical step in production across various industries. Passive acoustic emissions provide a promising potential for inline powder mixing monitoring. Vibrations from these emissions were measured during rotations of a V-blender using glass beads as a model solid as well as starch granules. Vibration profiles were correlated to specific phases of particle motion within the revolving V-shells. The phase, labeled Feature #1b, associated with particle collisions of the V-shell lid with attached accelerometer provided the largest measured vibration amplitudes and most reliable and relevant information on particle movement. After wavelet filtering to remove large-scale vibrations of the V-shell, the optimal information extraction method was identified as the average of the 50 highest amplitudes within the Feature #1b phase. An example illustrating the mixing of two size ranges of granules shows the potential of this monitoring method for pharmaceutical powder mixing in V-blenders. • Passive acoustic emissions are measured by a sensor on the lid of a V-blender. • Passive acoustic emissions from collisions reflect particle size and flow. • The largest emission amplitudes occur from collisions with the V-blender lids. • The 50 largest emissions amplitudes allow a mixing profile to be estimated.

Searches for Gravitational Waves from Known Pulsars at Two Harmonics in the Second and Third LIGO-Virgo Observing Runs

We present a targeted search for continuous gravitational waves (GWs) from 236 pulsars using data from the third observing run of LIGO and Virgo (O3) combined with data from the second observing run (O2). Searches were for emission from the l = m = 2 mass quadrupole mode with a frequency at only twice the pulsar rotation frequency (single harmonic) and the l = 2, m = 1, 2 modes with a frequency of both once and twice the rotation frequency (dual harmonic). No evidence of GWs was found, so we present 95% credible upper limits on the strain amplitudes h 0 for the single-harmonic search along with limits on the pulsars’ mass quadrupole moments Q 22 and ellipticities ε. Of the pulsars studied, 23 have strain amplitudes that are lower than the limits calculated from their electromagnetically measured spin-down rates. These pulsars include the millisecond pulsars J0437−4715 and J0711−6830, which have spin-down ratios of 0.87 and 0.57, respectively. For nine pulsars, their spin-down limits have been surpassed for the first time. For the Crab and Vela pulsars, our limits are factors of ∼100 and ∼20 more constraining than their spin-down limits, respectively. For the dual-harmonic searches, new limits are placed on the strain amplitudes C 21 and C 22. For 23 pulsars, we also present limits on the emission amplitude assuming dipole radiation as predicted by Brans-Dicke theory.

Contralateral Suppression of Transient-evoked Otoacoustic Emissions in Leisure Noise Exposed Individuals.

Leisure noise may have a significant impact on hearing thresholds and young adults are often exposed to loud music during leisure activities. This behavior puts them at risk of developing noise-induced hearing loss (NIHL). A frequent initial indication of NIHL is reduced hearing acuity at 4 kHz. The objective of the current study was to assess the role of the medial olivocochlear reflex (MOCR) in leisure noise-exposed individuals with and without a 4-kHz notch. Audiological evaluation, including pure-tone and immittance audiometry, was performed for 156 college-going, young adults between May 2019 to December 2019. All participants had averaged pure-tone audiometric thresholds within normal limits, bilaterally. Annual individual exposure to personal listening devices (PLDs) was calculated using the Noise Exposure Questionnaire. The participants were then categorized into exposed (with and without audiometric 4 kHz notch) and nonexposed groups. Transient-evoked otoacoustic emission amplitude and its contralateral suppression were measured using linear and nonlinear click stimuli to study the effect of leisure noise exposure on MOCR. A significantly reduced overall contralateral suppression effect in participants exposed to PLD usage (P = 0.01) in both linear and nonlinear modes. On the contrary, significantly increased suppression was observed in linear mode for the 4 kHz frequency band in the PLD-exposed group without an audiometric notch (P = 0.009), possibly suggesting an early biomarker of NIHL. Measuring contralateral suppression of otoacoustic emissions may be an effective tool to detect early NIHL in leisure noise-exposed individuals.

The effect of increase in blood glucose level on hearing loss

ObjectivePrevious studies have shown that hearing function is also vulnerable to the effects of diabetes mellitus which can be shown by brainstem auditory evoked potential and distortion product otoacoustic emission recordings. This study aimed to investigate the changes of brainstem auditory evoked potential and distortion product otoacoustic emission in hyperglycemia and whether there is a relationship between reactive oxygen substances production and hearing deterioration in the rat model. Methods25 streptozotocin induced diabetic rats were divided into three groups: control, high blood glucose, and diabetes mellitus. Brainstem auditory evoked potential and distortion product otoacoustic emission were recorded, and thiobarbituric acid reactive substances levels were measured in the brainstem tissue. ResultsAt 8 kHz, the latencies of I, II, III, IV, and V brainstem auditory evoked potential waves in high blood glucose and diabetes mellitus groups were elongated, at 16 kHz, only these wave latencies of the diabetes mellitus group were prolonged compared with the control group. A significant decrease was also found in distortion product otoacoustic emission amplitudes at 4, 6, 8, and 10 kHz in the high blood glucose and diabetes mellitus groups compared to the control group. There was a significant increase in thiobarbituric acid reactive substances values due to the increase in blood glucose levels in the high blood glucose and diabetes mellitus groups compared to the control group. ConclusionThese results suggested that high blood glucose levels may cause hearing impairment not only in the diabetic state but also in the period of hyperglycemia before the onset of manifest diabetes mellitus and reactive oxygen substances may play an important role in the pathophysiology of diabetes mellitus. We suggest that regulating high glucose levels even before the onset of manifest diabetes mellitus may prevent hazardous effects on hearing function. Level of evidenceLevel 3.

Terahertz radiation from propagating acoustic phonons based on deformation potential coupling.

We report on new THz electromagnetic emission mechanism from deformational coupling of acoustic (AC) phonons with electrons in the propagation medium of non-polar Si. The epicenters of the AC phonon pulses are the surface and interface of a GaP transducer layer whose thickness (d) is varied in nanoscale from 16 to 45 nm. The propagating AC pulses locally modulate the bandgap, which in turn generates a train of electric field pulses, inducing an abrupt drift motion at the depletion edge of Si. The fairly time-delayed THz bursts, centered at different times (t1T H z, t2T H z, and t3T H z), are concurrently emitted only when a series of AC pulses reach the point of the depletion edge of Si, even without any piezoelectricity. The analysis on the observed peak emission amplitudes is consistent with calculations based on the combined effects of mobile charge carrier density and AC-phonon-induced local deformation, which recapitulates the role of deformational potential coupling in THz wave emission in a formulatively distinct manner from piezoelectric counterpart.

Single-band tunable metasurface for thermal emitters in 5G bands

In communications, controlling the absorptivity and emissivity of the metasurface emitters is a meaningful area of research. However, the reported emitters mainly employ a continuous external energy to support the operating state, resulting in continuous energy consumption. In this work, a metasurface thermal emitter based on phase-change material Ge2Sb2Te5 (GST) is proposed and verified. This thermal emitter shows selective emission performance independent of continuous external heat source in the 26–32 GHz. Since the GST array reveals crystalline and amorphous phases, this emitter achieves a maximum emission amplitude of 0.95 and a minimum emission amplitude of 0.17. Therefore, by switching the crystalline and amorphous states of the GST array, this emitter can achieve a maximum modulation depth of 0.78. The continuous modulation of the emission performance of this transmitter is achieved through varying the annealing temperature. At the same time, since the phase transition state of GST is thermally stable (the phase transition state can remain stable even if the external thermal conditions fail), the thermal emission performance of this thermal emitter does not require continuous energy consumption to maintain. This continuously tunable, switchable mode, and thermally stable metasurface emitter has potential applications in infrared imaging, thermophotovoltaics, 5G communications, radiative cooling, and more.

Detection of middle-ear muscle reflex activation using changes in otoacoustic emission stimulus amplitude versus absorbance: an initial investigation

Objectives The medial olivocochlear reflex (MOCR) reduces cochlear amplifier gain, which may be beneficial for hearing in noise. Additionally, measurement of the MOCR may be diagnostically useful in the audiology clinic. The MOCR can be measured as the change in transient-evoked otoacoustic emission (TEOAE) amplitude without versus with contralateral acoustic stimulation (CAS). However, CAS can activate the middle-ear muscle reflex (MEMR) which can confound the MOCR results. MEMR activation has been assessed using changes in TEOAE stimulus amplitude without versus with CAS. As an initial investigation, the current study compared detection of MEMR activation using changes in TEOAE stimulus amplitude to changes in wideband absorbance. Methods In 26 normal-hearing participants, the MEMR was measured as the change in absorbance and as the change in TEOAE stimulus amplitude without and with CAS. Percentile critical differences were developed from the test-retest measurements. Measures of agreement between MEMR detection methods were computed. Results CAS resulted in a larger number of participants exceeding the 95th percentile critical difference for absorbance compared to TEOAE stimulus amplitude (22 versus 1). Agreement between methods was low. Conclusion Initial results indicated that MEMR was detectable in a larger number of participants when using absorbance compared to TEOAE stimulus amplitude. However, future work could better equate the two methods and include measurement of MEMR thresholds to determine optimal methods for detecting MEMR activation during MOCR assessments.

Rings and strings: a basis for understanding subleading colour and QCD coherence beyond the two-jet limit

Guided by the colour-diagonal structure of collinear singularities, we identify a set of kinematic basis functions that are well suited to the simplification of soft gluon emission amplitudes. In particular, these basis functions, which emerge naturally in the colour flow basis, isolate the subleading colour contributions and improve the statistical convergence of the CVolver amplitude-evolution code. They also allow us to extend current angular-ordered parton showers beyond the azimuthally-averaged, two-jet limit.

Study on vibratory leaching behavior and damage evolution of cement stabilized macadam (CSM)

Leaching is one of the main causes of water damage to the highway base, which can aggravate under the vibrations of the highway load and substantially deteriorate the durability of highway. To investigate the effect of the leaching of cement stabilized macadam (CSM) under vibration condition, a new method was reported in this study accelerate the leaching of CSM in a laboratory by changing the parameters such as vibration frequency, vibration time, leaching medium, etc. The vibration leaching behavior and damage evolution of CSM were studied by comparing the results of the vibration non-leaching test and the vibration leaching test. The main test indexes were calcium ion concentration, pH, leaching depth, ultrasonic wave velocity, unconfined compressive strength, splitting strength and acoustic emission amplitude. The results indicated that vibration could accelerate the leaching efficiency, and the acceleration effect can be changed by changing the vibration frequency. The performance of CSM considerably deteriorated due to leaching. With the increase in the leaching time, the leaching depth increased continuously, and the unconfined compressive strength and splitting strength decreased considerably; moreover, the damage accumulation increased. The durability of CSM was substantially reduced. The effect of the leaching of low-dose CSM is more obvious than that of high-dose CSM.

Does glutaric aciduria type 1 affect hearing function?

This study aimed to evaluate audiological findings among patients with glutaric aciduria type 1 (GA-1). We used a large test battery for the audiological evaluation of 17 individuals with GA-1 (the study group) and 20 healthy individuals (the control group). Conventional audiometry (0.125-8kHz), distortion product otoacoustic emissions (DPOAEs) (1, 1.5, 2, 3, 4, 6, and 8kHz), contralateral suppression of otoacoustic emissions, and auditory brainstem response (ABR) ( 30, 50, 70 and 90 dB nHL) were measured for all participants (n = 37). Mild sensorineural hearing loss was found in 77.47% (n = 13) of the patients with GA-1, and normal hearing thresholds were seen in 23.53% (n = 4). There were three asymptomatic patients at the time of diagnosis [two developed mild mental motor retardation (MMR) and one developed severe MMR during the follow-up], one with a normal hearing threshold and two with mild hearing loss), and 14 symptomatic patients (three with normal hearing thresholds and 11 with mild hearing loss). Seven of the symptomatic patients diagnosed following an encephalopathic crisis required intensive care and showed significantly worse hearing thresholds than those without symptoms [20.86 ± 4.47 vs. 15.44 ± 3.96 decibel hearing level (dB HL), p = 0.039*], while five had mild-to-moderate hearing loss. Acute encephalopathic crisis had a negative effect on hearing function in the symptomatic patients. The emission and contralateral suppression amplitude values of the study group were significantly lower compared to the control group (p < 0.05). The I-V interpeak latency and absolute latencies of ABR waves I, III, and V of the study group were observed to be significantly prolonged and morphologically distorted compared to those of the control group (p < 0.05). Five patients had MMR, and three had moderate MMR; all eight had mild-to-moderate hearing loss. In addition, of the eight patients with mild MMR, four had mild hearing loss. In particular, the morphological findings of ABR waves were significantly worse in the patients with severe and moderate MMR (p < 0.05). There was a significant correlation between a macrocephaly history (12 patients) and hearing loss (p = 0.041*). Magnetic resonance imaging findings were evaluated in all the 17 patients with GA-1, and typical fronto-temporal atrophy and sylvian fissure enlargement were observed. Our findings support that GA-1 is associated with auditory impairment, primarily in symptomatic patients. Adequate audiological test battery evaluation is essential in this context, particularly for symptomatic patients with a history of encephalopathic crises.

THz emission from Fe/Pt spintronic emitters with L10-FePt alloyed interface

SummaryRecent developments in nanomagnetism and spintronics have enabled the use of ultrafast spin physics for terahertz (THz) emission. Spintronic THz emitters, consisting of ferromagnetic (FM)/non-magnetic (NM) thin film heterostructures, have demonstrated impressive properties for the use in THz spectroscopy and have great potential in scientific and industrial applications. In this work, we focus on the impact of the FM/NM interface on the THz emission by investigating Fe/Pt bilayers with engineered interfaces. In particular, we intentionally modify the Fe/Pt interface by inserting an ordered L10-FePt alloy interlayer. Subsequently, we establish that a Fe/L10-FePt (2 nm)/Pt configuration is significantly superior to a Fe/Pt bilayer structure, regarding THz emission amplitude. The latter depends on the extent of alloying on either side of the interface. The unique trilayer structure opens new perspectives in terms of material choices for the next generation of spintronic THz emitters.

Performance Characterization of 450 nm Visible Light Based Photoacoustic Imaging for Phantom Imaging of Synthetic Dye Contrast Agents

&lt;p class="AbstractText"&gt;Performance characterization of 450 nm visible light photoacoustic imaging has been carried out through phantom imaging of methylene blue (MB), methyl orange (MO), and methyl red (MR) dye solutions. The phantom was made of a nylon tube with a diameter of 5.0 mm (outside) and 4.6 mm (inside) having a height of 2.0 mm along with a 6×6 cm black galvanized aluminum plate as the background medium. The nylon tube was filled with each type of solution with varying molecular concentrations of 10, 25, 50 and 100 ppm. Twelve (12) phantom objects were imaged in an area of 10×10 cm. The visible absorption peak known from UV-Visible spectroscopy for each type of solution is at 664 nm (methylene blue), 465 nm (methyl orange), and 522 nm (methyl red). It was also known that the amplitude of PA emissions would increase proportionally to the concentration of dye molecules. Overall, methyl orange solutions had the highest photoacoustic emission amplitude distribution. The analysis showed that the ratio of inner diameter (ID) and wall thickness (WT) between the MB and MO phantom images to the original object were 1:0.83 and 1:0.74 (ID) and 1:3 and 1:1.5 (WT), respectively. On the other hand, the ratio of the outer diameter (OD) of the MR phantom image to the original object is 1:1.28. &lt;/p&gt;

The Relationship of Lightning Radio Pulse Amplitudes and Source Altitudes as Observed by LOFAR.

When a lightning flash is propagating in the atmosphere it is known that especially the negative leaders emit a large number of very high frequency (VHF) radio pulses. It is thought that this is due to streamer activity at the tip of the growing negative leader. In this work, we have investigated the dependence of the strength of this VHF emission on the altitude of such emission for two lightning flashes as observed by the Low Frequency ARray (LOFAR) radio telescope. We find for these two flashes that the extracted amplitude distributions are consistent with a power‐law, and that the amplitude of the radio emissions decreases very strongly with source altitude, by more than a factor of 2 from 1 km altitude up to 5 km altitude. In addition, we do not find any dependence on the extracted power‐law with altitude, and that the extracted power‐law slope has an average around 3, for both flashes.

SLAC T-510 experiment for radio emission from particle showers: Detailed simulation study and interpretation

Over the last several decades, radio detection of air showers has been widely used to detect ultra-high-energy cosmic rays. We developed an experiment under controlled laboratory conditions at SLAC with which we measured the radio-frequency radiation from a charged particle shower produced by bunches of electrons as primaries with known energy. The shower took place in a target made of High Density Polyethylene located in a strong magnetic field. The experiment was designed so that Askaryan and magnetically-induced components of the radio emission could be measured independently. At the same time, we performed a detailed simulation of this experiment to predict the radio signal using two microscopic formalisms, endpoint and ZHS. In this paper, we present the simulation scheme and make a comparison with data characteristics such as linearity with magnetic field and amplitude. The simulations agree with the measurements within uncertainties and present a good description of the data. In particular, reflections within the target that accounted for the largest systematic uncertainties are addressed. The prediction of the amplitude of Askaryan emission agrees with measurements to within 5% for the endpoint formalism and 11% for the ZHS formalism. The amplitudes of magnetically-induced emission agree to within 5% for the endpoint formalism and less than 1% for the ZHS formalism. The agreement of the absolute scale of emission gives confidence in state-of-the-art air shower simulations which are based on the applied formalisms.

Spintronic terahertz emitters exploiting uniaxial magnetic anisotropy for field-free emission and polarization control

We explore the terahertz (THz) emission from CoFeB/Pt spintronic structures in the below-magnetic-saturation regime and reveal an orientation dependence in the emission, arising from in-plane uniaxial magnetic anisotropy (UMA) in the ferromagnetic layer. Maximizing the UMA during the film deposition process and aligning the applied magnetic field with the easy axis of the structure allow the THz emission to reach saturation under weaker applied fields. In addition, the THz emission amplitude remains at saturation levels when the applied field is removed. The development of CoFeB/Pt spintronic structures that can emit broadband THz pulses without the need for an applied magnetic field is beneficial to THz magneto-optical spectroscopy and facilitates the production of large-area spintronic emitters. Furthermore, by aligning the applied field along the hard axis of the structure, the linear polarization plane of the emitted THz radiation can be manipulated by changing the magnitude of the applied field. We, therefore, demonstrate THz polarization control without the need for mechanical rotation of external magnets.

Magnon-phonon interaction and the underlying role of the Pauli exclusion principle

The magnon-phonon interaction is receiving growing attention due to its key role in spin caloritronics and the emerging field of acoustic spintronics. At resonance, this magnetoelastic interaction forms magnon polarons, which underpin exotic phenomena such as magnonic heat currents and phononic spin, but is mostly investigated using mesoscopic spin-lattice models. Motivated to integrate the magnon-phonon interaction into first-principles many-body electronic structure theory, we set out to derive the exchange contribution, which is subtler than the spin-orbit contribution, using Schwinger functional derivatives. To avoid having to solve the famous Hedin-Baym equations self-consistently, the phonons are treated as perturbations to the electronic structure. A formalism based on imposing a crossing-symmetric electron-electron interaction is developed in order to treat charge and spin on equal footing to respect the Pauli exclusion principle. Due to spin conservation, the magnon-phonon interaction first enters to second order through the magnon-magnon interaction, which renormalizes the magnons. We show by iteration that the magnon-magnon interaction contains a ``screened $T$ matrix'' term and an arguably more important term which, in the local-spin limit, enables first-principles phonon emission and absorption amplitudes, predicted by phenomenological magnetoelastic models. These terms are, respectively, of first and second order in the screened collective four-point interaction $\mathcal{W}$---a crossing-symmetric analog of Hedin's $W$. Proof-of-principle results are presented at varying temperatures for an isotropic magnon spectrum in three dimensions in the presence of a flat optical phonon branch.

Composition-dependent ultrafast THz emission of spintronic CoFe/Pt thin films

We measure the transient THz emission of ultrathin spintronic bilayers composed of a cobalt–iron alloy (CoxFe1−x) and platinum (Pt), depending on the Co content 0 ≤ x ≤ 1. We find that the THz emission amplitude changes only slightly over the entire concentration range, indicating that Fe and Co contribute similarly to the THz generation process. Additionally, we fabricate multilayer stacks and find that the THz amplitude is increased by up to 36% compared to a single bilayer CoFe/Pt spintronic emitter.

Ototoxicity of an association of insecticides compounds containing dichlorvos and cypermethrin in Wistar rats

Purpose: to evaluate possible ototoxicity secondary to exposure to a combination of pesticides (dichlorvos and cypermethrin based insecticides). Methods: the Wistar rats were divided into 3 groups (12 animals per group): control (water), positive control for hearing damage (cisplatin) and experimental (exposed to dichlorvos and cypermethrin). The amplitude of distortion product otoacoustic emissions was assessed before and after the exposure. Systemic toxicity signs were also evaluated (clinical signs, weight gain and plasma cholinesterase). Wilcoxon test analyzed the post-exposure amplitudes compared to pre-exposure and Kruskal Wallis following Dunn’s post hoc tests analyzed the amplitudes’ variation. Normally distributed variables were evaluated by Student's t test. Results: body weight and plasma cholinesterase values were similar comparing the pre and post exposure in the experimental group. The control group did not manifest significant amplitude reduction of otoacoustic emissions between the pre and post evaluation. In the group exposed to cisplatin there was a significant reduction in amplitudes at 12 kHz on the right (p = 0.006; Wilcoxon) and 4 kHz on the left (p = 0.032; Wilcoxon). In the group exposed to pesticides, there was a significant reduction in the right ear at 4 kHz (p = 0.034; Wilcoxon) and 8 kHz (p = 0.019; Wilcoxon) and in the left ear at 4 kHz (p = 0.007; Wilcoxon), 6 kHz (p = 0.023; Wilcoxon), 8 kHz (p = 0.045; Wilcoxon) and 12 kHz (p = 0.028; Wilcoxon). Conclusion: there was ototoxicity in the experimental group, without a relevant systemic toxicity.

What is responsible for cochlear damage in patients with obstructive sleep apnea? Hypoxia or snoring noise?

Abstract Aim: Our aim in this study was to determine early cochlear changes caused by hypoxia and snoring noise in patients with Obstructive sleep apnea Syndrome and to examine the relationship of these changes with polysomnography parameters. Materials and Methods: A total of 149 patients with symptoms of snoring and sleep apnea who underwent polysomnography were included in this study. We formed a patient and control group based on the apnea-hypopnea index. We compared the audiometric parameters and the Distortion Product Otoacoustic Emission amplitudes of the groups. We evaluated Polysomnography parameters such as snoring number, snoring index, oxygen desaturation index, minimum pO2, mean pO2, pO2 ≤88%, which affect these results, by correlation. Results: High frequency audiometry and high frequency Distortion Product Otoacoustic Emission amplitudes showed statistically significant differences in the Obstructive Sleep Apnea Syndrome group compared to the control group (p&lt;0.001). PO2 ≤88% affected high frequency audiometry and mean pO2 affected high frequency Distortion Product Otoacoustic Emission amplitudes more than snoring number and snoring index. (p&lt;0.001). Conclusion: İn patients with OSAS, the inner ear is affected by hypoxia and snoring. However, the effect of hypoxia on cochlear dysfunction is greater than snoring noise. High-frequency audiometry and Distortion Product Otoacoustic Emission can guide in the early period to determine cochlear damage.