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The Bio-Radar is herein presented as a non-contact radar system able to capture vital signs remotely without requiring any physical contact with the subject. In this work, the ability to use the proposed system for emotion recognition is verified by comparing its performance on identifying fear, happiness and a neutral condition, with certified measuring equipment. For this purpose, machine learning algorithms were applied to the respiratory and cardiac signals captured simultaneously by the radar and the referenced contact-based system. Following a multiclass identification strategy, one could conclude that both systems present a comparable performance, where the radar might even outperform under specific conditions. Emotion recognition is possible using a radar system, with an accuracy equal to 99.7% and an F1-score of 99.9%. Thus, we demonstrated that it is perfectly possible to use the Bio-Radar system for this purpose, which is able to be operated remotely, avoiding the subject awareness of being monitored and thus providing more authentic reactions. [ABSTRACT FROM AUTHOR]

Significance: Continuous-wave functional near-infrared spectroscopy has proved to be a valuable tool for assessing hemodynamic activity in the human brain in a noninvasively and inexpensive way. However, most of the current processing/analysis methods assume the head is a homogeneous medium, and hence do not appropriately correct for the signal coming from the scalp. This effect can be reduced by considering light propagation in a layered model of the human head, being the Monte Carlo (MC) simulations the gold standard to this end. However, this implies large computation times and demanding hardware capabilities. Aim: In this work, we study the feasibility of replacing the homogeneous model and the MC simulations by means of analytical multilayered models, combining in this way, the speed and simplicity of implementation of the former with the robustness and accuracy of the latter. Approach: Oxy- and deoxyhemoglobin (HbO and HbR, respectively) concentration changes were proposed in two different layers of a magnetic resonance imaging (MRI)-based meshed model of the human head, and then these changes were retrieved by means of (i) a typical homogeneous reconstruction and (ii) a theoretical layered reconstruction. Results: Results suggest that the use of analytical models of light propagation in layered models outperforms the results obtained using traditional homogeneous reconstruction algorithms, providing much more accurate results for both, the extraand the cerebral tissues. We also compare the analytical layered reconstruction with MC-based reconstructions, achieving similar degrees of accuracy, especially in the gray matter layer, but much faster (between 4 and 5 orders of magnitude). Conclusions: We have successfully developed, implemented, and validated a method for retrieving chromophore concentration changes in the human brain, combining the simplicity and speed of the traditional homogeneous reconstruction algorithms with robustness and accuracy much more similar to those provided by MC simulations. [ABSTRACT FROM AUTHOR]

Cryogenic fluid storage tanks of launch vehicles use polyurethane-based foam with multi-layered coating as an insulation system. Detection of metal-to-foam debonds in cryofoam with the multi-layered coating is challenging due to the high attenuation of ultrasonic waves in cryofoam, the porous nature of the foam, varying substrate and foam thickness, etc. In this study a novel approach using dynamic depth focusing technique with Terahertz waves has been employed. Cryofoam sample with artificial metal-to-foam debonds is scanned with a continuous wave terahertz imaging system in reflection mode with a frequency range of 0.1 to 0.4 THz. The sample is raster scanned point by point in X-Y directions using a stepper motor. The reflected terahertz signal is received with a photomixer and Schottky detector to obtain a complete C-scan image. The debonds are not detectable by continuous-wave terahertz imaging due to the surface unevenness since the focal distance of the operating system is not variable. This report proposes a three-step procedure to perform dynamic depth focusing on multi-layer coated cryofoam samples. The first step involves the quantification of surface roughness at distinct points using a digital depth gauge to acquire the depth profile of the sample initially with a step size of 2 mm. A depth profile has been generated by interpolating the intermediate depth values as a second step. Finally, the focus of imaging is dynamically varied using a motorized stage at each imaging point based on the initially generated depth profile. This approach gives a better resolution at all depths without using geometry description tools like computer-aided design or other software tools. [ABSTRACT FROM AUTHOR]

Methods of reconstructing holographic images of objects made of the composite based on carbon fibermodified acrylonitrile-butadiene styrene and a thin electrically conductive film are presented. Holograms are obtained in the axial scheme when the collimating lens is placed on the source axis. Results of comparison of the calculated frequency response of the model transmission coefficient with measurements on an experimental setup are presented. [ABSTRACT FROM AUTHOR]

Nowadays, developing the radio frequency (RF)-photonic sensors suitable for several Defence and civil applications is emerging due to its various unique advantages. In today's scientific world, the involvement of low radar cross-section (RCS) airspace targets, such as unman aerial vehicles, drones, mini-helicopters, ornithopters, bionic birds, etc., is more for the purpose of airspace traffic management/guidance, materials delivery, legal/illegal surveillance and Defence/offense applications. The detection and recognition of such targets using the conventional RF sensors (which process only the main Doppler) is almost impossible. Therefore, extracting the distinctive micro-Doppler (m-D) signatures of these low-RCS targets and using them to image/differentiate/recognize their postures become significant which is the main contribution in this paper. A C-band continuous wave RF-photonic sensor is developed and different low-RCS targets: 2/3 blades rotating propeller system (drones), cone like structure (warhead) and a bionic-bird (spy-bird); are operated in front of it. The different nonlinear postures, of these targets, covered in our experimental measurements are m-D extraction of a slowly moving propeller system, detection of back-and-forth movements of a rotational propeller system, discerning the moving and static rotational propeller systems, simultaneous extraction of m-D signatures of a rotational and moving targets and recognition of flapping/gliding motions of bionic-bird. The analysis and recognition of all these postures using the experimentally generated m-D signatures are described. [ABSTRACT FROM AUTHOR]

The purpose of this study was to analyse the changes in flare values after Micropulse Transscleral Laser Treatment for Glaucoma (MP-TLT) in patients with refractory glaucoma and to compare with the outcomes of patients who underwent continuous wave (CW) diode laser cyclophotocoagulation (CW-TSCPC). In this single-centre study, we reviewed the medical records of 54 patients who underwent MP-TLT and 35 patients who underwent CW-TSCPC at Ankara University Faculty of Medicine, Department of Ophthalmology. Aqueous flare values were measured by laser flare photometry. The mean laser flare values in both groups (MP-TLT/CW-TSCPC) increased after surgery from 20.85 ± 8.74/22.14 ± 7.39 ph/ms at baseline to 48.52 ± 18.23/57.38 ± 20.08 ph/ms (P =.001) on day 1 and then progressively decreased to 44.13 ± 18.32/52.24 ± 20.56 in week 1, 40.5 ± 18.5/48.24 ± 19.23 week 2 and 35.28 ± 17.09/41.11 ± 16.7 month 1 (all p <.05) and returned to similar levels to baseline at month 3 and month 6 (both p >.05). Patients who achieved treatment success had significantly higher flare values than patients who failed on post-operative day 1, week 1 and week 2 in both groups. The flare values were significantly lower in the MP-TLT group than the CW-TSCPC group on post-operative day 1, week 1, week 2 and month 1 (all p <.05). There were no cases of prolonged post-operative inflammation or serious complications in both groups. Intraocular inflammation, quantified by aqueous flare, may be a contributing factor to the IOP lowering effect of transscleral diode laser cyclophotocoagulation in the early post-operative period. [ABSTRACT FROM AUTHOR]

Control applications targeting fast industrial processes rely on real-time feasible implementations. One of such applications is the stabilization of an electron bunch arrival time in the context of a linear accelerator. In the past, only the electric field accelerating the electron bunches was actively controlled in order to implicitly stabilize the accelerated electron beam. Nowadays, beam properties are specifically measured at a target position and then stabilized by a dedicated feedback loop acting on the accelerating structures. This dedicated loop is usually referred to as a beam-based feedback (BBF). Following this, the control system of the electron linear accelerator for beams with high brilliance and low emittance (ELBE) is planned to be upgraded by the BBF, and the problem of implementing a designed control algorithm becomes highly relevant. In this work, we propose a real-time feasible implementation of a high-order H 2 regulator based on a field-programmable gate array (FPGA). By presenting simulation and synthesis results made in hardware description language (HDL) VHDL, we show that the proposed digital solution is fast enough to cover the bunch repetition rates frequently used at ELBE, such as 100 kHz . Finally, we verify the implementation by using a dedicated FPGA testbench. [ABSTRACT FROM AUTHOR]

As two-terminal passive fundamental circuit elements with memory characteristics, memristors are promising devices for applications such as neuromorphic systems, in-memory computing, and tunable RF/microwave circuits. The increasingly complex electromagnetic interference (EMI) environment threatens the reliability of memristor systems. However, various EMI signals' effects on memristors are still unclear. This paper selects continuous waves (CWs) as EMI signals. It provides a deeper insight into the interference effect of CWs on the memristor driven by a sinusoidal excitation voltage, as well as a method for investigating the EMI effect of memristors. The optimal memristor model is obtained by the exhaustive traversing of the possible model parameters, and the interference effect of CWs on memristors is quantified based on this model and the proposed evaluation metrics. Simulation results indicate that CW interference may affect the switching time, dynamic range, nonlinearity, symmetry, time to the boundary, and variation of memristance. The specific interference effect depends on the operating mode of the memristor, the amplitude, and the frequency of the CW. This research provides a foundation for evaluating EMI effects and designing electromagnetic protection for memristive neuromorphic systems. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effects of pre- and postnatal 2450 MHz continuous wave (CW) radiofrequency radiation (RFR) on the thymus of rats spanning four generations. Four groups; sham, irradiated female, irradiated male, irradiated male and female, each consisting of four rats (one male and three females), were created. During the experiment, rats in the exposure groups were whole-body exposed to 2450 MHz CW-RFR for 12 h/day. Irradiation started one month before the fertilization in the experimental group. When the offspring were two months old, four rats, one male and three female, were allocated for the second-generation study. The remaining offspring were sacrificed under general anesthesia, and their thymuses were removed. The same procedure was applied to the next generation. Two months after the second generation gave birth, third-generation rats were decapitated, and their thymuses were removed. In all groups, cortex, medulla and resident cells could be clearly distinguished in the second and third generations. No differences were observed between the control and two experimental groups, defined as irradiated female and irradiated male. In contrast, vascularization was observed in the thymus of the fourth-generation offspring of the group where both males and females were irradiated. The number of offspring and mass of all rats decreased in the third-generation group. Pre-and postnatal 2450 MHz continuous wave radiofrequency radiation exposure may potentially affect the thymus of future generations. [ABSTRACT FROM AUTHOR]

Purpose: To assess the safety and effectiveness of augmented MicroPulse (MP-TSCPC) with limited Continuous Wave Transscleral Cyclophotocoagulation (CW-TSCPC) in patients with refractory glaucoma. Methods: Thirty-eight eyes of 38 patients underwent combined MP-TSCPC and CW-TSCPC at Massachusetts Eye and Ear. Kaplan–Meier survival curves and Wilcoxon paired sign rank tests were performed to evaluate intraocular pressure (IOP), glaucoma medication burden, best corrected visual acuity (BCVA), and adverse events. Results: With success defined as IOP reduction ≥ 30% and IOP between 5 and 18 mmHg, the cumulative probability of success at 1 year and 1.5 years were 0.81 (95% confidence interval (CI), 0.68–0.96) and 0.65 (95% CI, 0.50–0.86), respectively. With success defined as IOP reduction ≥ 50% and IOP between 5 and 18 mmHg, the success probability at 1 year and 1.5 years were 0.72 (95% CI, 0.57–0.89) and 0.56 (95% CI, 0.40–0.78), respectively. IOP and medication burden reductions were significant at all follow-up visits compared to baseline. Average IOP decreased from 27.9 mmHg at baseline to 11.4 mmHg at 1 year (p < 0.001) and 10.0 mmHg at 1.5 years (p < 0.001). Average medication burden decreased from 3.8 to 1.7 at 1.5 years (p = 0.001). No significant differences in visual acuity were observed at any time point. No long-term sight-threatening complications due to the combined procedure were observed, and most of the complications observed were mild and transient. Conclusion: In patients with refractory glaucoma, the combination of augmented MP-TSCPC with limited CW-TSCPC provides a significant IOP-lowering effect and decrease in medication burden without increased risk of postoperative complications. [ABSTRACT FROM AUTHOR]

Cationic substitution in metal oxides induces defects that modify the ground state absorption and its nonlinear optical properties. Herein, the surface states, lattice disorders, and nonlinear properties of these microstructures are studied. The third-order optical nonlinearities of hydrothermally synthesized pristine MnCO 3 and Ce3+ and Y3+ substituted MnCO 3 microstructures are determined using single beam Z-scan transmittance analysis. As a result of controlling cationic defects in these microstructures, these materials exhibit tunable non-linear optical properties from Reverse Saturable Absorption (RSA) to Saturable Absorption (SA). The presence of surface states due to cationic substitution induces a transition from RSA to SA. The third-order optical nonlinearities exhibited by these microstructures when excited at a 633 nm continuous wave show enhanced efficiency which can be a potential candidate in optical switching applications. • Defect-induced cationic substitutions done in MnCO 3 microspheres by hydrothermal method. • Rare earth elements are incorporated in manganese ions as nano-engineered particles. • The nano-engineered particles are excited with a CW 633 nm to explore its third-order optical nonlinearities. [ABSTRACT FROM AUTHOR]

We continue the comparative studies of high-power AlGaAs/InGaAs/GaAs semiconductor lasers with different waveguide designs. In this work, measurements were carried out for a continuous-wave mode of operation: lightâ€"current and currentâ€"voltage characteristics, threshold characteristics and their temperature dependences and crystal temperature depending on the pump current. The data obtained made it possible to reconstruct the dependences of internal optical losses and internal quantum efficiency using calculations. It was shown that the main factor affecting the power characteristics in the continuous mode of operation is the temperature stability of the laser and its relationship with internal optical losses and internal quantum efficiency. Thus, lasers based on a heterostructure with a doped GaAs waveguide with characteristic temperatures T 0 and T 1 of 120 K and 170 K, respectively, demonstrated an increase in internal optical losses to 2 cmâˆ'1 and a drop in the quantum efficiency to 90%, which led to saturation of the output power by high pump currents. Lasers based on the heterostructure with an AlGaAs waveguide, which are characterized by higher temperature stability (T 0 = 161 K and T 1 = 280 K), had lower internal optical losses and a higher quantum efficiency. This made it possible to obtain optical power 1 W higher than that for lasers with GaAs waveguides. [ABSTRACT FROM AUTHOR]

A high power, high‐conversion‐efficiency, and tunable continuous‐wave external cavity pump singly resonant optical parametric oscillator (OPO) was proposed in this article. This OPO was based on multi‐grating MgO‐doped stoichiometric periodically poled LiTaO3 (MgO:sPPLT) and pumped with 532 nm continuous wave fiber laser. The MgO:sPPLT‐OPO could provide near‐infrared radiation across 821–879 nm in the signal and 1352–1515 nm in the idler within four grating periods of 8.3–8.6 μm. When the pump power was 5.4 W, the maximum pump‐to‐signal conversion efficiency could reach 57.5% at 821 nm. The output power extended to 5.9 W in each period when the pump power reaches 13.6 W. [ABSTRACT FROM AUTHOR]

In this paper, we propose a non-contact ultrasonic liquid flowmeter based on AlN piezoelectric micromachined ultrasonic transducer (PMUT) arrays. Two 10 by 10 PMUT arrays with resonant frequency of 980 kHz in air are mounted outside of a pipe to measure liquid flow without contacting the liquid. An acoustic matching layer is designed to mitigate the loss of sound waves caused by sound reflection. Under excitation of continuous wave, the flow of the liquid can be determined via detecting the phase difference between transmitting and received signals. The measurement range of flow is 0.515 L/min ~ 3.40 L/min and the measurement error is less than 3%. Moreover, an interpolation method is proposed to reduce the signal sampling frequency without obviously affecting the measurement accuracy, which shows potential for further system integration. [2021-0033] [ABSTRACT FROM AUTHOR]

Protein dynamics is at the heart of all cellular processes. Here, we utilize the dHis‐CuIINTA label to obtain site‐specific information on dynamics for both an α‐helix and β‐sheet site of GB1, the immunoglobulin binding domain of protein G. Spectral features found in our CW‐EPR measurements were consistent with the overall rigid nature of GB1 and with predictions from molecular dynamics simulations. Using this information, we show the potential of this approach to elucidate the role of dynamics in substrate binding of a functionally necessary α‐helix in human glutathione transferase A1‐1 (hGSTA1‐1). We observe two dynamical modes for the helix. The addition of the inhibitor GS‐Met and GS‐Hex resulted in hGSTA1‐1 to favor the more rigid active state conformation, while the faster mode potentially aids the search for substrates. Together the results illustrate the remarkable potential of the dHis‐based labelling approach to measure site‐specific dynamics using room temperature lineshape analysis. [ABSTRACT FROM AUTHOR]

Protein dynamics is at the heart of all cellular processes. Here, we utilize the dHis‐CuIINTA label to obtain site‐specific information on dynamics for both an α‐helix and β‐sheet site of GB1, the immunoglobulin binding domain of protein G. Spectral features found in our CW‐EPR measurements were consistent with the overall rigid nature of GB1 and with predictions from molecular dynamics simulations. Using this information, we show the potential of this approach to elucidate the role of dynamics in substrate binding of a functionally necessary α‐helix in human glutathione transferase A1‐1 (hGSTA1‐1). We observe two dynamical modes for the helix. The addition of the inhibitor GS‐Met and GS‐Hex resulted in hGSTA1‐1 to favor the more rigid active state conformation, while the faster mode potentially aids the search for substrates. Together the results illustrate the remarkable potential of the dHis‐based labelling approach to measure site‐specific dynamics using room temperature lineshape analysis. [ABSTRACT FROM AUTHOR]

We report on a high-power continuous-wave (CW) intracavity frequency-doubled laser at 670.8 nm, which is produced by the second-harmonic generation of a diode side-pumped Nd:YAP crystal laser with a type-II noncritically phase-matched LBO crystal. A maximum output power up to 13 W at 670.8 nm is obtained with an optical-to-optical (808 nm → 671 nm) efficiency of 2.4%. The beam quality factor M2 is measured to be 8.85, and the fluctuation (RMS) of output power is < ± 0.6% over 30 min. To the best of our knowledge, this is the highest power for the CW laser at 670.8 nm. [ABSTRACT FROM AUTHOR]

We propose a broadband end-fire antenna for continuous-wave terahertz (THz) photomixing–based devices working in the frequency range of 0.5–1 THz. A compact Vivaldi antenna is presented that does not require any hyper-hemispherical silicon lens to collect and collimate THz radiation unlike the conventionally used broadside antennas. The antenna is tailored to radiate THz into or receive radiation from a dielectric waveguide placed in close vicinity of it. The antenna is fabricated on an indium phosphide (InP) substrate. A silicon (Si) superstrate is used to improve the directionality of the radiated beam. THz power coupled into Si waveguides is measured using two different techniques between 0.1 and 1.15 THz. Firstly, the waveguide is placed in the optical path of a 1550 nm based continuous-wave THz setup with a commercial broadside emitter, focusing optics, and a detector fabricated on the InP substrate with log-periodic broadside antenna. Secondly, the waveguide is placed in direct contact with the designed Vivaldi antenna–based THz receiver and using the commercial broadside emitter as a source. It is observed that the direct coupling technique using the Vivaldi end-fire antenna outperforms the optically coupled approach at frequencies higher than 668 GHz. Efficient THz photoconductive sources and receivers based on the designed compact Vivaldi end-fire antenna will be suitable for launching THz power into on-chip THz circuitry and for compact THz systems. [ABSTRACT FROM AUTHOR]

Terahertz waves (T-ray) were extensively studied for the nondestructive evaluation of the characterization of trailing edges composed with composite materials. The NDE system consisted of both continuous wave (CW) and time domain spectroscopy (TDS). The FRP composites were utilized for both trailing edges of wind energy (non-conducting polymeric composites) and carbon fiber composites with conducting properties. The signals of T-ray in the TDS mode almost resembles that of ultrasound waves; however, a terahertz pulse could not penetrate a material with conductivity, unlike ultrasound. The refractive index (n) was utilized as one of the material properties, so a method was suggested to obtain the "n" in the materials. The data of refractive index (n) were utilized due to obtained data for the trailing edges. The trailing edges were scanned for charactering and inspecting. C-scan and B-scan images were obtained and the optimal NDE techniques were suggested for complicated geometry samples by terahertz radiation. In particular, the penetrating time-of-flight (TOF) of T-ray corresponded with the calculated TOF for the trailing edges with greater thickness (about 70 mm). [ABSTRACT FROM AUTHOR]

In this paper, a new form of combined pulsed laser (CPL) consisting of continuous wave (CW) laser and nanosecond (ns) pulse train was proposed for drilling Q235B steel without high-pressure gas jet. The average power of CW laser ranged from 100 to 700 W, while the average power of the ns laser was fixed at 12 W. The experiments were carried out to study the influence of the average CW laser power on the drilling efficiency and quality of CPL. The results show that there were two completely different matching mechanisms between the CW laser and ns pulse train. Firstly, during the CPL drilling with the 100-200 W CW laser, the ns pulse train could be used to timely and periodically eject the central part of the molten metal, leaving a recast layer with a thickness of up to 200 μm. In addition, for the CPL drilling with the 550 W CW laser, a little part of molten metal was continuously ejected by the ns pulse train, and all of the remaining molten metal could be removed by the boiling of molten metal, thus leaving a recast layer with thickness less than 10 μm. The new CPL presented in this paper has an important guiding significance for improving the quality and making full use of the high efficiency of CW laser drilling. [ABSTRACT FROM AUTHOR]

Moisture content of foodstuffs are typically assessed by Titration or Near Infrared Spectroscopy, which are labour‐intensive as a manual measurement or costly when automated. Magnetic resonance offers a method for moisture evaluation but is also normally costly. In this work, we revisit Look and Locker's "Tone Burst" experiment with a marginal oscillator to evaluate moisture content of powdered–skimmed milk subjected to increased humidity. We refer to this technique as the Transient Effect Determination of Spin–Lattice (TEDSpiL) relaxation times. Moisture content in the samples ranged from 0–12% as determined from the weight gained by the dry powder when re‐suspended in water to reach a concentration of 40% w/v. The relaxation properties of re‐hydrated samples were measured with a CW NMR sensor. Solutions made up from powders with a higher retained moisture content provided lower measured relaxation values providing a method of measuring the moisture content of the powder. This technique provides a moisture measurement in under 5∼s compared with several minutes for the equivalent pulsed method using low‐field hardware. [ABSTRACT FROM AUTHOR]

Ultraviolet light-emitting diode (UV-LED) is a newly emerging UV light source with a potential to replace the conventional chemical methods, mercury UV lamps and xenon lamps in water disinfection. UV-LEDs are characterized by the diversity in wavelengths and can be turned on and off with a high and adjustable frequency, making them an attractive candidate for pulsed light (PL) disinfection apart from the conventional continuous wave (CW) operation. Previous studies on comparison between the PL and CW UV-LED irradiations for the inactivation of bacterium in water disinfection are limited and results conflict. In this work, PL and CW UV-LED in the C-spectral band (UVC-LED) irradiations were compared at equivalent fluence in the inactivation and subsequent photoreactivation of E. coli bacteria. In addition, effect of different driving currents and ambient temperatures on solder temperature of the PL and CW UVC-LED irradiation was also examined. Under the equivalent fluences, the PL and CW UVC-LED irradiations brought comparable inactivation efficiency and similar photoreactivation of the E. coli. Moreover, the PL UVC-LED exhibited a much lower solder temperature than the CW UVC-LED irradiation. On the other hand, CW UVC-LED irradiation, higher ambient temperature and higher driving current increased the solder temperature that resulted to a negative impact on the wavelength, full width at half maximum, optical power and irradiance, which are key factors in the UVC-LED disinfection efficiency. In all, this work reports the comparison between PL and CW in UVC-LED irradiation for inactivating E. coli bacteria and firstly revealed the photoreactivation of the E. coli after the PL UVC-LEDs irradiation. Image 1 • PL and CW irradiations brought comparable inactivation efficiency and similar photoreactivation. • PL operation suppresses the temperature rising from CW operation in UVC-LEDs. • 268 nm UVC-LED caused slightly higher inactivation efficiency in both PL and CW operations. • 275 nm UVC-LED exhibited a much lower photoreactivation and a lower solder temperature. [ABSTRACT FROM AUTHOR]

Coherent continuous wave (CW) terahertz spectroscopy is an extremely valuable technique that allows for the interrogation of systems that exhibit narrow resonances in the terahertz (THz) frequency range, such as high-quality (high-Q) THz whispering-gallery mode resonators. Unfortunately, common implementations are impaired by deficiencies in the used data analysis schemes. Here, we show that these deficiencies can be conveniently overcome using the Hilbert transform, and we unveil the theoretical foundations of the method. In particular, by establishing that signals encountered in typical experiments are closely related to analytic signals, we demonstrate that Hilbert transform is applicable even when the envelope varies rapidly compared to the oscillation period. Compelling results from experimental measurements and numerical simulations confirm the broad applicability of the described method. [ABSTRACT FROM AUTHOR]

Continuous wave THz (cw THz) systems define the state-of-the-art in terms of spectral resolution in THz spectroscopy. Hitherto, acquisition of broadband spectra in a cw THz system was always connected with slow operation. Therefore, high update rate applications like inline process monitoring and non-destructive testing are served by time domain spectroscopy (TDS) systems. However, no fundamental restriction prevents cw THz technology from achieving faster update rates and be competitive in this field. In this paper, we present a fully fiber-coupled cw THz spectrometer. Its sweep speed is two orders of magnitude higher compared to commercial state-of-the-art systems and reaches a record performance of 24 spectra per second with a bandwidth of more than 2 THz. In the single-shot mode, the same system reaches a peak dynamic range of 67 dB and exceeds a value of 100 dB with averaging of 7 min, which is among the highest values ever reported. The frequency steps can be as low as 40 MHz. Due to the fully homodyne detection, each spectrum contains full amplitude and phase information. This demonstration of THz-spectroscopy at video-rate is an essential step towards applying cw THz systems in non-destructive, in line testing. [ABSTRACT FROM AUTHOR]

• The high-power 635 nm red laser in the compact all-fiber format based on visible dielectric-coated fiber mirror technology and the down-conversion gain. • The highest continuous-wave output power of fiber laser operating in the visible wavelength region to date. • Comparative experiments were performed on the reflectivity of the output mirror and the length of the active fiber to optimize the results. We propose and experimentally demonstrate a compact high-power all-fiber Pr3+-doped red laser at 635 nm using highly-resistant dielectric-coated fiber mirror. The fiber laser consists of a 443 nm pump laser diode (LD), a double-clad Pr3+-doped fluoride fiber and a 443/635 nm dichroic fiber mirror. The 635 nm laser is directly generated by down-conversion gain of the Pr3+-doped fiber pumped by the 443 nm LD. The homemade dichroic fiber mirror is specifically designed for anti-reflection at 443 nm pump wavelength and high-reflection at 635 nm laser wavelength, and shows a high damaged density of >15 MW/cm2, which is very favorable to high-power visible laser operation. The red all-fiber laser directly generates a highest average power of ∼5 W at 635 nm which is more than twofold higher than previously reported, and the slope efficiency is as high as 25.7%. Different from the traditional visible laser by frequency doubling, this work offers a promising way for miniaturized, high-power fiber lasers in visible wavelength region. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nickel and cobalt substituents in manganese tungstate (MnWO 4) resulting in the formation of superstructures. • Z-scan transmittance analysis, excited with 633 nm of continuous wave exhibit Reverse Saturable Absorption (RSA). • The superstructures exhibit enhanced nonlinearities than the pristine MnWO 4 nanorods. • RSA increases with increase in reduced Graphene Oxide (rGO) wt.% is an evident of charge transitions between rGO and MnWO 4. The smart filtering effects of Manganese tungstate/reduced Graphene Oxide (MnWO 4 /rGO,) and Nickel and cobalt doped Manganese tungstate/reduced Graphene Oxide (Mn (1-x+y) Ni x Co y WO 4 /rGO) self-assembled urchin like microspheres are explored. Their relevant optical nonlinearities are related with that of pristine MnWO 4 nanorods. The third order optical nonlinearities are characterized by a Z-scan analysis with continuous wave regime of 633 nm (He:Ne laser). The highest nonlinear attenuation is attributed to Mn (1-x+y) Ni x Co y WO 4 /rGO (5 wt%) microstructures. The intensity dependent absorption β (m / W) and nonlinear index of refraction n 2 ( cm 2 /W) is determined to be 4.8 × 10−4 and 8.8 × 10−7. The maximum attainable optical susceptibility χ TOT 3 is 16.8 × 10−8 esu. The morphology of pristine MnWO 4 nanorods and urchin like microstructures is evidenced using HRSEM images. The defect D and optical phonon G bands from the Raman signal besides the A g υ 1 modes confirms the materialization as nanocomposite. [ABSTRACT FROM AUTHOR]

Gravitational wave astronomy opened dramatically in September 2015 with the LIGO discovery of a distant and massive binary black hole coalescence. The more recent discovery of a binary neutron star merger, followed by a gamma ray burst (GRB) and a kilonova, reinforces the excitement of this new era, in which we may soon see other sources of gravitational waves, including continuous, nearly monochromatic signals. Potential continuous wave (CW) sources include rapidly spinning galactic neutron stars and more exotic possibilities, such as emission from axion Bose Einstein 'clouds' surrounding black holes. Recent searches in Advanced LIGO data are presented, and prospects for more sensitive future searches are discussed. [ABSTRACT FROM AUTHOR]

Traditional synthetic aperture radar (SAR) imaging relies on wideband transformed waveforms. SAR using narrowband continuous waveforms (NCW) has been proved to be also able to achieve high resolution imaging exploiting high Doppler resolution. NCW-SAR has the following advantages： it occupies very small band resources, it promotes the development of low-cost and small SAR, it is much applicable to passive SAR using illuminators of opportunity, which usually transmits waveforms with relatively narrow bandwidth. Firstly, the application potential of NCW-SAR is pointed out. The development of narrowband imaging is briefly reviewed and the state of art NCW-SAR imaging technology is analyzed. Then, a general SAR received signal model is presented and afterwards, a moving target imaging method for NCW-SAR is proposed to focus the moving targets on the ground scene. The velocity estimation method as well as the velocity resolution analysis is also presented. The simulation results demonstrate the effectiveness of the proposed NCW-SAR moving target imaging method. [ABSTRACT FROM AUTHOR]

We demonstrate a comparative analysis of directly diode-pumped Tm3+-doped all-fibre laser operating at 1908 nm with different structure at fibre end facets. The feedback arising from parasitic oscillations and amplified spontaneous emission can be suppressed by coating an anti-reflection on the forward end facet and cleaving an angle on the backward end facet. 44.1 W laser power on forward end at the pumped power of 120 W was achieved. The forward laser slope efficiency was 39.3%, corresponding to the backward laser slope efficiency of 3.0%. The beam quality factor ofM2was 1.4. [ABSTRACT FROM PUBLISHER]

The 1 064 nm lasing, and 1 074 nm, and 1 084 nm luminescence are observed in a Nd:YVO4 DPSSL along with their corresponding SHG. Fundamental transitions are analyzed in terms of Stark effect. The relative intensity of the 1 064 nm laser line is an order of magnitude bigger than the luminescence lines. [ABSTRACT FROM AUTHOR]

The electrical characteristics of tissue yield valuable information for early diagnosis of pathological changes. Magneto-acoustic imaging is a functional approach for imaging of electrical conductivity. This study proposes a continuous-wave magneto-acoustic imaging method. A kHz-range continuous signal with an amplitude range of several volts is used to excite the magneto-acoustic signal and improve the signal-to-noise ratio. The magneto-acoustic signal amplitude and phase are measured to locate the acoustic source via lock-in technology. An optimisation algorithm incorporating nonlinear equations is used to reconstruct the magneto-acoustic source distribution based on the measured amplitude and phase at various frequencies. Validation simulations and experiments were performed in pork samples. The experimental and simulation results agreed well. While the excitation current was reduced to 10 mA, the acoustic signal magnitude increased up to 10-7 Pa. Experimental reconstruction of the pork tissue showed that the image resolution reached mm levels when the excitation signal was in the kHz range. The signal-to-noise ratio of the detected magneto-acoustic signal was improved by more than 25 dB at 5 kHz when compared to classical 1 MHz pulse excitation. The results reported here will aid further research into magneto-acoustic generation mechanisms and internal tissue conductivity imaging. [ABSTRACT FROM AUTHOR]

Monitoring physiological signs in animal testing is crucial for the development of new therapeutic strategies and better understanding of diseases. This paper exploits Doppler radar and nonlinear phase demodulation effect to achieve noncontact measurement of both displacements and frequencies of a laboratory rat’s cardiorespiratory activities. The implementation of displacement acquisition method relying on demodulation-generated harmonics is described, and this paper provides a guideline of implementing the acquisition method. Demodulation-generated harmonics are analyzed, and the effect of vibration-generated harmonics is studied. To demonstrate the effectiveness, a 60-GHz radar is used that shows good correlation with the instrument-recorded data. Average errors of respiration rate and heart rate (HR) are 0.057% and 0.33%, respectively, using three test subjects. In addition, two drug tests are performed to verify the monitoring function with controlled raised/dropped HR. By observing the time periods before, during, and after drug injection, results of rat’s physiological response to drugs reveal the drug efficacy and body reaction over time. The measured cardiorespiratory variations can provide useful information without using implant devices, and the implementation could be an improvement over current invasive methods. The result presented in this paper is believed to be the first reported simultaneous measurements of both frequencies and displacements of both respiration and heartbeat movements of a laboratory animal using microwave radar. [ABSTRACT FROM AUTHOR]

The continuous wave shows greater potential than the pulse signal to achieve high-accuracy ultrasound speed measurement thanks to its stronger noise resistance. However, the accuracy of ultrasound speed measurement would deteriorate if echoes exist in the received continuous wave. This paper presents an applicable method using the maximum length sequence-modulated continuous wave. The present method improves the accuracy of ultrasound speed measurement further by resisting echoes. The time delay between the received signal and the transmitted signal is estimated accurately by combining the cross-correlation, parabolic interpolation and phase shift technique. Moreover, both the inherent delays induced by physical system and the path length of ultrasound are expediently corrected through least square estimation. As a result, accurate time of flight and ultrasound speed measurement are achievable. For example, the standard deviation of ultrasound speed measurement in distilled water is less than 0.003 m/s, and the deviation between the ultrasound speed measurement and the reference is less than 0.04 m/s. [ABSTRACT FROM AUTHOR]

An improved triple-pulse high-power pulse-width modulation (HP-PWM) signal model is proposed to enhance the performance of current underwater sonar transmitter. The presented model is based on reducing the third and fifth harmonic energy of the HP-PWM signal. The achievement of low-power consumption has been implemented using class D amplifier and high-quality factor (High-Q) underwater acoustic transducer (UAT). High efficiency is demonstrated by simulations (reducing 41 % of the third and fifth harmonic energy). Feasibility of the presented model under different conditions has been proved by experiments. [ABSTRACT FROM AUTHOR]

While building aerodynamics have been widely studied, most investigations have been conducted in wind tunnels or through computational simulation. Full-scale experiments are least common, as they are usually costly, require significant time and effort and are subject to uncontrolled meteorological conditions. This research examines the feasibility of using a continuous-wave Doppler Lidar, as opposed to traditional experimental instrumentation for flow measurements around full-scale buildings. The normalised mean velocities and the turbulence intensities measured around a full-size, nominally cuboid building in suburban terrain were compared to results from Cobra multi-hole pressure probes mounted on the full-size building and from a 1/100-scale wind-tunnel test. The normalised mean velocities measured in the tests were within 2% of each other; however, the turbulence intensities obtained from the wind-tunnel experiments were 2–6% higher than the nominal value of 14% measured in the full-scale testing. These effects appeared mainly due to the relatively low sampling frequency of the Lidar, combined with the spatial averaging over a relatively large area. It was concluded that Lidar instrumentation shows promise for characterising the flowfield around full-scale buildings, if the scanning cone angle can be reduced and the sampling rate increased. [ABSTRACT FROM AUTHOR]

The development of new technologies and industry increases the number and variety of electromagnetic field (EMF) sources. Researcher are increasingly interested in the effects of EMF on brain health. The brain's function is largely dependent on electrical excitability, so it would be expected to be vulnerable to EMF. We therefore investigated the effects of brain development in the fetus, histopathological changes in female rats and the hippocampal level of MAPK proteins in male rats after exposed to pre and postnatal 2450 MHz continuous wave (CW) radiofrequency radiation (RFR) over four generations. Four groups; sham, irradiated female, irradiated male, irradiated male and female, with each consisting of four rats (one male and three females) were created. Rats in the exposure groups were whole-body exposed to 2450 MHz CW-RFR for 12 h/day during the experiment. Irradiation started one month before fertilization in the experimental group. On the 18th day of the gestational period, one pregnant rat from each group was decapitated under general anesthesia and the fetuses were taken. The remaining two pregnant rats completed the normal gestation period. When the offspring were two months old, four rats, one male and three female, were allocated for the second generation study. Next generation animals were also experienced the same processes as the first generation rats. This study were evaluated development of brain in fetuses and histopathological changes in brain of female rats using haematoxylin eosin staining, and the hippocampal level of MAPK proteins in brain of male rats by Western Bloting. We observed hemorrhagic areas, irregular cellular localization and vascular structures in the brain of fetal and adult female rat of exposed groups in the all generations. pERK, ptau, pJNK and pP38 were increased in the brain of adult male rat of exposed groups in the all generations (p < 0.005). Pre and postnatal 2450 MHz continuous wave radiofrequency radiation exposure may cause changes in the function of the MAPK pathway affecting cognitive processes such as learning and memory and may cause damage to both the fetus and adult brain tissue. Also, EMF may have potential to affect brain of future generations. • One of the important topics is effect of radiofrequency electromagnetic fields (RF-EMFs) on the central nervous system. • EMF may cause changes in the function of the MAPK pathway, which affects cognitive processes such as learning and memory. • EMF may cause damage to both fetal and adult brain tissue in rats. • Sufficient data are not available on generation studies investigate bio-effects of RF-EMFs. [ABSTRACT FROM AUTHOR]

The new heavy ion superconducting continuous wave HElmholtz LInear ACcelerator (HELIAC) is under construction at GSI. A normal conducting injector, comprising an ECR ion source, an RFQ and a DTL, is recently in development. The new Interdigital H-mode DTL, presented in this paper, accelerates the heavy ion beam from 300 to 1400 keV/u, applying an Alternating Phase Focusing (APF) beam dynamics scheme. This APF section, consisting of two separately controlled tanks, has to provide for stable routine operation with assistance of dedicated beam diagnostics devices in the Intertank section. The installed quadrupole lenses and beam steerers installed there ensure full transmission in a wide range of input beam parameters. [Display omitted] • Alternating phase focusing has been applied for low emittance growth heavy ion beam transport. • Realistic 6D coupling for all phase planes has been considered. • Two radio frequency resonators have been designed to provide for continuous wave operation. • For beam dynamics design, a parallel global optimization search strategy has been adopted. [ABSTRACT FROM AUTHOR]

The authors demonstrate two types of non‐reciprocal waveform‐selective metasurfaces that control the level of reflectance, depending not only on the direction of the incident wave but also on the waveform, namely, on the pulse width. A capacitor‐based waveform‐selective metasurface exhibits strong reflectance for a short pulse compared to that for a continuous wave (CW) at the same frequency. In contrast, an inductor‐based waveform‐selective metasurface more strongly reflects a CW than a pulse. The difference between them is demonstrated to be more than 50% but is reduced for a wave propagating in the other direction. The concept of the authors' structures is expected to offer an additional degree of freedom with which to design non‐reciprocal devices and applications. [ABSTRACT FROM AUTHOR]

Articles by Dr Brian Hall in War in History and the Journal of Military History cavalierly dismiss the book Missed Signals on the Western Front: How the Slow Adoption of Wireless Restricted British Strategy and Operations in World War I. This rebuttal questions his understanding of continuous wave technology and points out that, in contrast to the British effort, the Americans provided their forces with modern wireless communications. Hall chose to dismiss rather than engage with the book’s disagreement with his assertion that the British army was remarkably successful at recognizing the utility of wireless and exploiting its full military potential. [ABSTRACT FROM AUTHOR]

Measuring amplitude and phase of continuous ultrasonic waves with a lock-in amplifier is shown to give similarly sensitive indicators of concrete damage as pulsed coda wave analysis, but maintains its sensitivity at considerably much lower signal levels. Continuous and pulsed measurements were performed on a concrete slab subjected to cyclically increased damage level. In the unloaded phase each measurement type was performed at varying transmit signal levels. The result indicates the possibility of using a larger distance between transducers in high frequency health monitoring systems of concrete structures, where attenuation of propagating waves is strong. [ABSTRACT FROM AUTHOR]

Present generations are being repeatedly exposed to different types and doses of non-ionizing radiation (NIR) from wireless technologies (FM radio, TETRA and TV stations, GSM and UMTS phones/base stations, Wi-Fi networks, DECT phones). Although there is controversy on the published data regarding the non-thermal effects of NIR, studies have convincingly demonstrated bioeffects. Their results indicate that modulation, intensity, exposure duration and model system are important factors determining the biological response to irradiation. Attempting to address the dependence of NIR bioeffectiveness on these factors, apoptosis in the model biological systemDrosophila melanogasterwas studied under different exposure protocols. A signal generator was used operating alternatively under Continuous Wave (CW) or Frequency Modulation (FM) emission modes, at three power output values (10 dB, 0, −10 dB), under four carrier frequencies (100, 395, 682, 900 MHz). Newly emerged flies were exposed either acutely (6 min or 60 min on the 6th day), or repeatedly (6 min or 60 min daily for the first 6 days of their life). All exposure protocols resulted in an increase of apoptotic cell death (ACD) observed in egg chambers, even at very low electric field strengths. FM waves seem to have a stronger effect in ACD than continuous waves. Regarding intensity and temporal exposure pattern, EMF-biological tissue interaction is not linear in response. Intensity threshold for the induction of biological effects depends on frequency, modulation and temporal exposure pattern with unknown so far mechanisms. Given this complexity, translating such experimental data into possible human exposure guidelines is yet arbitrary. [ABSTRACT FROM AUTHOR]

This paper is to investigate numerically the photothermal response of the most common size of gold nanoshell (AuNS) in an aqueous medium for biomedical applications. Three types of laser light irradiate the particle; a continuous-wave (CW), short (nanosecond) and ultrashort (femtosecond) pulse laser. The spatiotemporal evolution of the temperature profile inside and around the AuNS is computed using a numerical framework based on the finite element method (FEM). For CW and nanosecond (ns) pulse laser where the AuNS’s electrons and lattice are at thermal equilibrium, the ordinary heat diffusion equation is used to describe the heat transfer to the surrounding water. For femtosecond (fs) pulse laser, due to the inexistence of the thermal equilibrium, a two-temperature model (TTM) is used to describe the heat transfer processes occurring in the AuNS and the normal heat diffusion equation is used for the heat flux calculation at the particle/water interface. For each case, the influence of laser intensity on the maximum temperature reached at the particle/water interface is studied. The aim of this study is to provide a description for the fundamentals of heat release of AuNSs and useful insights for the development of these particles for biomedical applications such as drug delivery, photothermal cancer therapy and optoporation of cells. [ABSTRACT FROM AUTHOR]

The European XFEL will operate nominally at 17.5 GeV in SP (short pulse) mode with 0.65 ms long bunch train and 10 Hz repetition rate. A possible upgrade of the linac to CW (continuous wave) or LP (long pulse) modes with a corresponding reduction of electron beam energy is under discussion for many years. Recent successes in the dedicated R&D program allow to forecast a technical feasibility of such an upgrade in the foreseeable future. One of the challenges is to provide sub-Ångström FEL operation in CW and LP modes. In this paper we perform a preliminary analysis of a possible operation of the European XFEL in the hard X-ray regime in CW and LP modes with electron energies of 7 GeV and 10 GeV, respectively. We consider lasing in the baseline XFEL undulator as well as in a new undulator with a reduced period. We show that, with reasonable requirements on electron beam quality, lasing on the fundamental will be possible in the sub-Ångström regime. As an option for generating brilliant photon beams at short wavelengths we also consider harmonic lasing that has recently attracted a significant attention. [ABSTRACT FROM AUTHOR]

Highlights: [•] A secondary Rabi resonance is revealed under amplitude-modulated continuous wave excitation. [•] Large Fourier components are observed at harmonics of the modulation frequency. [•] Experiments agree with theoretical predictions derived from the Bloch equation. [Copyright &y& Elsevier]

The techniques of frequency modulated continuous wave (FMCW) and laser intensity modulation by a linear saw tooth-swept voltage controlled oscillator (VCO) are integrated with a kind of all-fibre micro-vibration vector sensor in this research. A senor multiplexing method aimed at detecting multipoint feeble vibration signals using only a long single mode fibre (SMF) is reported. In this system, a high sensitive photodetector is employed to execute photoelectric conversion. Its output is subsequently mixed with a branch of reference saw tooth chirped signal so as to obtain beat components, which provide information necessary for locating the position of each sensor. Theoretical analysis of the signals from each part is made in detail. The simulation results are exhibited and reveal the effectiveness and feasibility of this method. [ABSTRACT FROM AUTHOR]

Abstract: This year marks the 20th anniversary of functional near-infrared spectroscopy and imaging (fNIRS/fNIRI). As the vast majority of commercial instruments developed until now are based on continuous wave technology, the aim of this publication is to review the current state of instrumentation and methodology of continuous wave fNIRI. For this purpose we provide an overview of the commercially available instruments and address instrumental aspects such as light sources, detectors and sensor arrangements. Methodological aspects, algorithms to calculate the concentrations of oxy- and deoxyhemoglobin and approaches for data analysis are also reviewed. From the single-location measurements of the early years, instrumentation has progressed to imaging initially in two dimensions (topography) and then three (tomography). The methods of analysis have also changed tremendously, from the simple modified Beer-Lambert law to sophisticated image reconstruction and data analysis methods used today. Due to these advances, fNIRI has become a modality that is widely used in neuroscience research and several manufacturers provide commercial instrumentation. It seems likely that fNIRI will become a clinical tool in the foreseeable future, which will enable diagnosis in single subjects. [Copyright &y& Elsevier]

Abstract: This review is aimed at presenting the state-of-the-art of time domain (TD) functional near-infrared spectroscopy (fNIRS). We first introduce the physical principles, the basics of modeling and data analysis. Basic instrumentation components (light sources, detection techniques, and delivery and collection systems) of a TD fNIRS system are described. A survey of past, existing and next generation TD fNIRS systems used for research and clinical studies is presented. Performance assessment of TD fNIRS systems and standardization issues are also discussed. Main strengths and weakness of TD fNIRS are highlighted, also in comparison with continuous wave (CW) fNIRS. Issues like quantification of the hemodynamic response, penetration depth, depth selectivity, spatial resolution and contrast-to-noise ratio are critically examined, with the help of experimental results performed on phantoms or in vivo. Finally we give an account on the technological developments that would pave the way for a broader use of TD fNIRS in the neuroimaging community. [Copyright &y& Elsevier]

Near-infrared stimulation (NIS) is an emerging technique used to evoke action potentials in nervous systems. Its efficacy of evoking action potentials has been demonstrated in different nerve tissues. However, few studies have been performed using NIS to stimulate the deep brain structures, such as globus pallidus (GP) and subthalamic nucleus (STN). Male Sprague-Dawley rats were randomly divided into GP stimulation group (n = 11) and STN stimulation group (n = 6). After introducing optrodes stereotaxically into the GP or STN, we stimulated neural tissue for 2 min with continuous near-infrared light of 808 nm while varying the radiant exposure from 40 to 10 mW. The effects were investigated with extracellular recordings and the temperature rises at the stimulation site were also measured. NIS was found to elicit excitatory responses in eight out of 11 cases (73%) and inhibitory responses in three cases in the GP stimulation group, whereas it predominantly evoked inhibitory responses in seven out of eight cases (87.5%) and an excitatory response in one case in STN stimulation group. Only radiation above 20 mW, accompanying temperature increases of more than 2°C, elicited a statistically significant neural response (p < 0.05). The responsiveness to NIS was linearly dependent on the power of radiation exposure. [ABSTRACT FROM AUTHOR]