Corrigendum to "Multiband rabi antenna using nest microstrip add-drop filter (NMADF) for relativistic sensing applications" [Heliyon 9(2) (February 2023) e13611].

[This corrects the article DOI: 10.1016/j.heliyon.2023.e13611.].

Multiband Rabi antenna using nest microstrip add-drop filter (NMADF) for relativistic sensing applications.

A microstrip circuit is designed, constructed, and tested based on the nest microstrip add-drop filters (NMADF). The multi-level system oscillation is generated by the wave-particle behaviors of AC driven along the microstrip ring circular path. The continuous successive filtering is applied via the device input port. The higher-order harmonic oscillations can be filtered, from which the two-level system known as a Rabi oscillation is achieved. The outside microstrip ring energy is coupled to the inside rings, from which the multiband Rabi oscillations can be formed within the inner rings. The resonant Rabi frequencies can be applied for multi-sensing probes. The relationship between electron density and Rabi oscillation frequency of each microstrip ring output can be obtained and used for multi-sensing probe applications. The relativistic sensing probe can be obtained by the warp speed electron distribution at the resonant Rabi frequency respecting the resonant ring radii. These are available for relativistic sensing probe usage. The obtained experimental results have shown that there are 3-center Rabi frequencies obtained, which can be used for 3-sensing probes simultaneously. The sensing probe speeds of 1.1c, 1.4c, and 1.5c are obtained using the microstrip ring radii of 14.20, 20.12, and 34.49 mm, respectively. The best sensor sensitivity of 1.30 ms is achieved. The relativistic sensing platform can be used for many applications.

Porous Si-SiO2 based UV Microcavities.

Obtaining silicon-based photonic-structures in the ultraviolet range would expand the wavelength bandwidth of silicon technology, where it is normally forbidden. Herein, we fabricated porous silicon microcavities by electrochemical etching of alternating high and low refraction index layers; and were carefully subjected to two stages of dry oxidation at 350 °C for 30 minutes and 900 °C, with different oxidation times. In this way, we obtained oxidized porous silicon that induces a shift of a localized mode in the ultraviolet region. The presence of Si-O-Si bonds was made clear by FTIR absorbance spectra. High-quality oxidized microcavities were shown by SEM, where their mechanical stability was clearly visible. We used an effective medium model to predict the refractive index and optical properties of the microcavities. The model can use either two or three components (Si, SiO2, and air). The latter predicts that the microcavities are made almost completely of SiO2, implying less photon losses in the structure. The theoretical photonic-bandgap structure and localized photonic mode location showed that the experimental spectral peaks within the UV photonic bandgap are indeed localized modes. These results support that our oxidation process is very advantageous to obtain complex photonic structures in the UV region.

Planckian Power Spectral Densities from Human Calves during Posture Maintenance and Controlled Isometric Contractions.

BACKGROUND: The relationship between muscle anatomy and physiology and its corresponding electromyography activity (EMGA) is complex and not well understood. EMGA models may be broadly divided in stochastic and motor-unit-based models. For example, these models have successfully described many muscle physiological variables such as the value of the muscle fiber velocity and the linear relationship between median frequency and muscle fiber velocity. However they cannot explain the behavior of many of these variables with changes in intramuscular temperature, or muscle PH acidity, for instance. Here, we propose that the motor unit action potential can be treated as an electromagnetic resonant mode confined at thermal equilibrium inside the muscle. The motor units comprising the muscle form a system of standing waves or modes, where the energy of each mode is proportional to its frequency. Therefore, the power spectral density of the EMGA is well described and fit by Planck's law and from its distribution we developed theoretical relationships that explain the behavior of known physiological variables with changes in intramuscular temperature or muscle PH acidity, for instance. METHODS: EMGA of the calf muscle was recorded during posture maintenance in seven participants and during controlled isometric contractions in two participants. The power spectral density of the EMGA was then fit with the Planckian distribution. Then, we inferred nine theoretical relationships from the distribution and compared the theoretically derived values with experimentally obtained values. RESULTS: The power spectral density of EMGA was fit by Planckian distributions and all the theoretical relationships were validated by experimental results. CONCLUSIONS: Only by considering the motor unit action potentials as electromagnetic resonant modes confined at thermal equilibrium inside the muscle suffices to predict known or new theoretical relationships for muscle physiological variables that other models have failed to do.

The bifoil photodyne: a photonic crystal oscillator.

Optical tweezers is an example how to use light to generate a physical force. They have been used to levitate viruses, bacteria, cells, and sub cellular organisms. Nonetheless it would be beneficial to use such force to develop a new kind of applications. However the radiation pressure usually is small to think in moving larger objects. Currently, there is some research investigating novel photonic working principles to generate a higher force. Here, we studied theoretically and experimentally the induction of electromagnetic forces in one-dimensional photonic crystals when light impinges on the off-axis direction. The photonic structure consists of a micro-cavity like structure formed of two one-dimensional photonic crystals made of free-standing porous silicon, separated by a variable air gap and the working wavelength is 633 nm. We show experimental evidence of this force when the photonic structure is capable of making auto-oscillations and forced-oscillations. We measured peak displacements and velocities ranging from 2 up to 35 microns and 0.4 up to 2.1 mm/s with a power of 13 mW. Recent evidence showed that giant resonant light forces could induce average velocity values of 0.45 mm/s in microspheres embedded in water with 43 mW light power.

Effective tactile noise facilitates visual perception.

The fulcrum principle establishes that a subthreshold excitatory signal (entering in one sense) that is synchronous with a facilitation signal (entering in a different sense) can be increased (up to a resonant-like level) and then decreased by the energy and frequency content of the facilitating signal. As a result, the sensation of the signal changes according to the excitatory signal strength. In this context, the sensitivity transitions represent the change from subthreshold activity to a firing activity in multisensory neurons. Initially the energy of their activity (supplied by the weak signals) is not enough to be detected but when the facilitating signal enters the brain, it generates a general activation among multisensory neurons, modifying their original activity. In our opinion, the result is an integrated activation that promotes sensitivity transitions and the signals are then perceived. In other words, the activity created by the interaction of the excitatory signal (e.g., visual) and the facilitating signal (tactile noise) at some specific energy, produces the capability for a central detection of an otherwise weak signal. In this work we investigate the effect of an effective tactile noise on visual perception. Specifically we show that tactile noise is capable of decreasing luminance modulated thresholds.

Anomalous patterned scattering spectra of one-dimensional porous silicon photonic crystals.

Far-field secondary emission spectra of one-dimensional periodic photonic structures based on porous silicon show characteristic co-focal rings centered close to the structure plane normal. The rings appear when the frequency of picosecond excitation laser pulses is tuned to the edges of the fourth photonic band gap. They can be clearly distinguished from the typical reflected and transmitted light in the oblique incidence geometry. The rings number is dependent on the excitation frequency and the incidence angle. We explain these anomalous spectral features of porous silicon structures by the spectral filtering of light elastically scattered inside the photonic structure by the narrow photonic bands. The elastic scattering of light due to the photonic disorder in the structure causes the appearance of secondary waves propagating in any direction. But only those waves which fall into the allowed photonic bands penetrate through the whole structure and move through its front or back surfaces. The observed patterned secondary emission is an example of efficient photonic engineering by simple means of multilayer porous silicon structures.

Multiband negative refraction in one-dimensional photonic crystals.

We simulate a lossless one-dimensional photonic crystals (1DPC) structure and show that negative refraction could be present near the low frequency edge of at least the second, fourth and sixth bandgaps. We experimentally demonstrate for the first time negative refraction in strongly modulated porous silicon 1D-PC in the visible and near infrared regions. This 1D-PC structure may allow the realization of short-focus Veselago lenses in different optical bands. An advantage of our structure is its simplicity allowing for cheap and rapid fabrication of samples.

Multisensory integration: central processing modifies peripheral systems.

Multisensory integration in humans is thought to be essentially a brain phenomenon, but theories are silent as to the possible involvement of the peripheral nervous system. We provide evidence that this approach is insufficient. We report novel tactile-auditory and tactile-visual interactions in humans, demonstrating that a facilitating sound or visual stimulus that is exactly synchronous with an excitatory tactile signal presented at the lower leg increases the peripheral representation of that excitatory signal. These results demonstrate that during multisensory integration, the brain not only continuously binds information obtained from the senses, but also acts directly on that information by modulating activity at peripheral levels. We also discuss a theoretical framework to explain this novel interaction.

Readmission in unstable angina.

To determine the characteristics of patients re-admitted after unstable angina (UA) pectoris, 120 consecutive patients hospitalized due to primary UA pectoris were prospectively studied 22 +/- 3 months after discharge. The patients were grouped based on the readmission rate. Those in group A (50) had recurrent admissions (mean 2.6, range 2 to 5). Seventy patients (group B) did not have readmissions during the follow-up period. All patients underwent coronary angiogram and symptoms-limited exercise stress test before discharge. The univariate characteristics for readmission were: age over 70 years (p = 0.02), nondiagnostic exercise stress testing (p = 0.03), angiographically diffuse coronary artery disease (p = 0.004), and non-interventional management (P < 0.001). Patients readmitted had increased incidence of myocardial infarction (p = 0.004) but similar survival at 2 years. By regression analysis, important variables for readmission were non-interventional management (Chi-Square = 7.6, p = 0.01), non diagnostic treadmill test (Chi-Square = 6.9, p = 0.03) and diffuse coronary artery disease (Chi-Square = 6.2, p = 0.04). It is concluded that in the interventional era the most important factor for readmission after primary UA pectoris is non-interventional management. Coronary revascularization should not be denied solely on the basis of age.

Prevalence of ectopic ventricular activity after left ventricular mass regression.

To assess the effects of left ventricular mass reduction on the prevalence of ventricular ectopic activity, we conducted a double-blind, placebo-controlled trial measuring ambulatory 48 h premature ventricular depolarizations in 27 patients with mild-to-moderate hypertension and an increased left ventricular mass index. Data was obtained at baseline and 6 +/- 2 months after randomization to either 25 mg captopril or placebo twice a day. Patients on captopril attained reduction in blood pressure from 167 +/- 11/103 +/- 6 to 136 +/- 10/85 +/- 5 mm Hg (P = .001), left ventricular mass index regression from 149 +/- 17 to 96 +/- 23 g/m2 (P = .001), and ventricular ectopic activity reduction from 413 +/- 172 to 77 +/- 27 ventricular extrasystoles/day (P = .001). Patients on placebo had no significant change in blood pressure (from 162 +/- 11/101 +/- 6 at baseline to 160 +/- 8/100 +/- 8 mm Hg after 6 months; P = NS). In the placebo group left ventricular mass index increased from 155 +/- 40 to 182 +/- 51 g/m2 (P = .01), and ventricular ectopic activity decreased from 634 +/- 293 to 562 +/- 260 ventricular extrasystoles/day (P = NS). Eight out of 14 patients on captopril (57%) and 1 out of 13 patients on placebo (8%) achieved reduction > 85% in ventricular ectopic activity per day (P = .004). Using multivariate logistic regression analysis, left ventricular mass index regression and reduction in systolic blood pressure were the most important correlates for this effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of enalapril on ventricular volumes and neurohumoral status after inferior wall myocardial infarction.

The activation of the sympathetic nervous system and the renin-angiotensin-aldosterone system and its beneficial modification with the use of angiotensin-converting enzyme inhibin after inferior wall myocardial infarction (MI) was evaluated. Fifty patients with acute inferior MI were randomly assigned to receive 5 mg per day of either enalapril or placebo after admission. Blood tests for neurohormone levels and echocardiograms were performed at initial examination and 4 weeks later. Baseline characteristics were similar in the two groups. Four weeks after randomization, patients treated with enalapril had lower end-diastolic volume (146 +/- 29 vs 167 +/- 15 ml; p = 0.04), end-systolic volume (56 +/- 18 vs 107 +/- 17 ml; p = 0.03), serum norepinephrine levels (320 +/- 93 vs 465 +/- 77 pg/ml; p < 0.01), angiotensin II levels (18 +/- 6 vs 54 +/- 11 pg/ml; p < 0.01), and atrial natriuretic polypeptide levels (106 +/- 9 vs 122 +/- 17 pg/ml; p = 0.05) than patients given placebo. The incidence of heart failure after MI was also lower in this group (4% vs 16%; p = 0.009). Results show that there is early neurohumoral activation in the course of acute inferior wall MI. Enalapril reduces neurohumoral levels and preserves ventricular volumes. These effects were associated with a reduction in the incidence of heart failure 4 weeks after MI in these patients.

Reduction in cardiac conduction velocity delay by angiotensin converting enzyme inhibition in hypertensive patients with left ventricular hypertrophy. Detection by signal averaged electrocardiography.

Hypertensive patients with left ventricular hypertrophy (LVH) have increased prevalence of ventricular arrhythmias. Slow conduction velocity at the level of hypertrophic myocardial cells has been one of the postulated mechanisms for these arrhythmias. To assess the effects of angiotensin converting enzyme inhibition on modification in ventricular conduction velocities, we studied 25 hypertensive patients with LVH using signal averaged electrocardiography (SAECG) in a randomized double-blind placebo controlled and cross-over trial. Data were acquired at baseline and 10 min after a double-blind intravenous infusion of saline placebo or 2.5 mg enalaprilat. Sequential cross-over was done the next day. Root mean square vector was 55 +/- 5 microV at baseline, 55 +/- 5 microV after placebo and 54 +/- 4 microV after enalaprilat (P = NS). Low amplitude signal < 40 msec was 45 +/- 4 msec at baseline, 45 +/- 4 msec after placebo, and 43 +/- 4 msec after enalaprilat (P = NS). There was no change in filtered QRS (fQRS) duration between baseline (113 +/- 10 msec) and placebo (113 +/- 11 msec) measurements. However, after enalaprilat infusion, there was a significant reduction in fQRS to 106 +/- 7 msec (P = .04), and five patients (20%) with late potentials had normalization of this feature (P = .001). The data suggest that angiotensin converting enzyme inhibition with enalaprilat reduces conduction velocity delay in hypertensive patients with LVH.

Effects of enalapril on heart failure in hypertensive patients with diastolic dysfunction.

Ten hypertensive patients with symptoms of heart failure and normal systolic function but with diastolic dysfunction were treated with 10 mg enalapril twice a day for 9 +/- 3 months to evaluate the effects of this agent alone on heart failure induced by diastolic dysfunction. After therapy, all patients improved and echocardiographic parameters of diastolic dysfunction became normalized. It is concluded that enalapril appears to be useful in the treatment of heart failure in hypertensive patients with normal systolic function and diastolic dysfunction.