bluuebunny/crossref_metadata_2025 huggingface dataset:
Passive pulse narrowing in actively-mode-locked diode-pumped solid-state lasers
Authors: Flood C. J. , Walker D. R. , van Driel H. M.
Published: February 2023

Actively mode-locked diode-pumped solid-state lasers regularly generate pulse widths which are several times shorter than those predicted by classical mode-locking theory.
Quasi-phase-matched second-harmonic generation from femtosecond pulses in chirped gratings
Authors: Wang G. Y. , Koehler S. D. , Garmire E. M.
Published: February 2023

We present an analysis of quasi-phase-matched (QPM) second-harmonic generation (SHG) from femtosecond mode-locked pulses with respect to conversion efficiency and pulse broadening dependence on pulse length.
Self-starting of passively-mode-locked lasers with fast saturable absorbers
Authors: Chen C. J. , Wai P. K. A. , Menyuk C. R.
Published: February 2023

Self-starting of passively modelocked lasers with fast saturable absorbers is examined.
Spectroscopy with nonclassical light
Authors: Kimble H. J. , Polzik E. S. , Georgiades N. , Mabuchi H.
Published: February 2023

A frequency tunable source of squeezed light has been developed for a variety of applications in atomic physics.
Correlated atomic states and quantum noise in spectroscopy
Authors: Wineland D. J. , Bollinger H. H. , Itano W. M. , Heinzen D. H. , Moore F. L
Published: February 2023

We have investigated, theoretically, the quantum mechanical noise in spectroscopic experiments on ensembles of two-level (or spin-1/2) particles where transitions are detected by measuring the changes in state population.1,2
Squeezed states of motion in ion traps
Authors: Cirac J. I.
Published: February 2023

We propose a scheme for preparing squeezed states of motion of a single ion trapped in a harmonic potential based on the multichromatic excitation of the ion.
Model of large-water-droplet deformation and destruction by CO2-laser radiation
Authors: Geints Yu E. , Zemlyanov A. A.
Published: February 2023

The appearance of droplet deformations is discussed at the expense of jet shock resulting from local surface ejections of water-vapor mix under the high-rate laser heating of the droplet.
Thermal-lens detection of one- and two- photon absorption in organic solvents
Authors: Kczich V. , Castillo J. , Marcano A.
Published: February 2023

In linear and nonlinear spectroscopic studies of liquids and solutions with long pulse or cw lasers, local heating of the sample has to be taken into account.1
Measurement of a fiber’s nonlinear refractive index by using a differential Sagnac interferometric method
Authors: Lee Hak Kyu , Kim Kyong Hon , Park Seo Yeon , Lee El Hang
Published: February 2023

The optical Kerr effect in optical fibers has attracted considerable interest recently for high speed optical time division demultiplexing, sampling, and pulse shaping.1 We have developed a new method to measure a small phase change induced by a low power pump light, by combining the differential interferometric technique2 with a Sagnac interferometer. A rotational acceleration is applied on the fiber spool of the Sagnac interferometer to perform differential Sagnac interferometric measurements. This method was employed in the measurements of the nonlinear refractive indices of a polarization maintaining fiber for both polarization states of a 1.053-μm mode-locked Nd:YLF laser pump beam with respect to that of a 1.53-μm-DFB laser diode signal. We were able to measure the light induced phase modulation as low as 10-2 radians. The cross-phase modulated nonlinear refractive indices measured with the pump beam’s polarization parallel and perpendicular to the signal beam’s polarization were 4.4 x 10-16 and 1.5 x 10-16 cm2/W, respectively. The ratio of the former value to the latter one is about 3, which is in a good agreement with theoretical calculation.3 Hence, the self-phase modulated nonlinear refractive index, n2, of our polarization maintaining fiber turns out to be 2.2 x 10-16 cm2/W.
Thermal-wave imaging system using a thin-film pyroelectric bimorph sensor element
Authors: Lee R. , Peralta S. B.
Published: February 2023

In photothermal, or thermal-wave, imaging, a laser beam is scanned across the front surface of a sample mounted on a temperature-sensitive sensor. A rastered image of the sample’s thermoacoustic properties is then built up by detecting the associated heat pulse propagation through the sample. Sensor materials most used in such thermal-wave imaging systems are conventionally ceramics such as lead zirconate titanate and single crystals such as triglycine-sulphate and lithium tantalate. Recently, polymer films such as polyvinyl fluoride and polyvinylidene fluoride have found increasing use,1,2 due to their flexibility, robustness, and relatively low cost. This work describes a thermal-wave imaging system based on a pyroelectric bimorph detector element. The sensor is based on a novel bilayer laminate configuration of pyroelectric polymer films, which has been shown to have a higher theoretical responsivity than for an equivalent singleelement film.3,4 Specific detectivity values for our sensor are approximately twice the value reported for the equivalent singlefilm element. This gain in detectivity continues up to about 100 Hz for polyvinylidene fluoride bimorphs; at higher laser modulation frequencies the thermal attenuation becomes larger and the specific detectivity decreases.
Automatic tolerance computation for lens systems
Authors: Crawford Charles
Published: February 2023

The tolerance computation for the design of mounts for a lens uses a geometric description of the ideal positions and optical properties of the elements. Given a geometric description of the mounts and the possible manufacturing and assembly errors we must solve a quality control problem [1,2]: 1. Find the effect of each error on the constructional parameters. 2. Using step 1, find the effect on the aberrations of each of the error. 3. Given the statistical distributions of errors, find the distributions of the aberrations. 4. Using the result of step 3, find the expected yield of manufactured lenses.
Optimization of grating-tooth shape in waveguide input-output couplers
Authors: Li Ming , Lin John C. H. , Chan Gordon S. F. , Sheard Stephen J.
Published: February 2023

Grating-assisted couplers have been widely studied over the past twenty years for use in guided-wave optics. The grating tooth shape strongly influences the radiation characteristics of the couplers.
Mutually pumped phase-conjugate mirror in a bidirectional ring resonator geometry
Authors: Yu Wenqian , Krolikowski Weislaw , Luther-Davies Barry
Published: February 2023

In a mutually-pumped phase-conjugate mirror (MPPCM) two in-coherent optical beams interact within a photorefractive crystal producing phase conjugate replicas of each other [1].
Nonlinearly transformed matched filters with random phase modulations in the Fourier plane
Authors: Zhang Guanshen , Javidi Bahram
Published: February 2023

Compared with conventional matched filters, nonlinearly transformed matched filters have superior correlation performance.1
Effects of a phase-conjugating external cavity on mode-locked argon-laser emission
Authors: Gay David , McCarthy Nathalie
Published: February 2023

It has been shown that the injection of a small fraction of the output beam back into the laser cavity improves the signal-to-noise ratio of a cw multilongitudinal mode argon laser efficiently.1
Effect of finite crystal size on cross talks in volume-holographic interconnects
Authors: Han Dong Kyoon , Jin Sang Kyu , Lee Hyuk
Published: February 2023

Optical interconnections have been investigated extensively as a promising interconnecting scheme in the area of neural networks and parallel electronic processing systems [1,2].
Dynamic holographic gratings
Authors: Olivares-Pérez A.
Published: February 2023

The holographic relief grating1 are made with photoresist.2
Absorption and emission spectra of trappedions
Authors: Mackay Peter E. , Oppo Gian-Luca
Published: February 2023

The resonance fluorescence spectrum of laser cooled ions in trapping potentials can provide useful information for ultra-high resolution spectroscopy.
Spatial-frequency tuning, contrast tuning, and spatial summation of suprathreshold lateral spatial interactions: grating induction and contrast–contrast
Authors: McCourt Mark E.
Published: February 2023

Two supra-threshold lateral interactions, the grating-induction effect,1 and the contrast–contrast effect,2,3 were compared regarding their dependence upon inducing grating spatial frequency, inducing and “victim” grating contrast, and inducing grating extent. Both effects cause “victim” gratings to be matched non-veridically. The respective magnitude of the effects was measured in common units which indexed the veridicality of contrast matches across a wide range (-0.9 to 0.9) of “victim” grating contrast. Grating induction had a low-pass, and contrast-contrast had a high-pass spatial frequency response, crossing over at ca. 1 c/d. Maximal grating induction strength exceeded that of contrast–contrast for 5 of 6 observers. Observers demonstrating strong grating induction tended to show weak contrast-contrast magnitudes, and vice versa. When inducing contrast was 0.75, the departures from veridical matching varied with “victim” grating contrast. For low frequencies (0.03125-0.125 c/d) grating induction produced a skewed unimodal departure from veridical matching, peaking at “victim” grating contrasts of 0.5. The pattern became bimodal at higher spatial frequencies (0.25-2.0 c/d) peaking at “victim” contrasts of ca. -0.3 and 0.5. Contrast–contrast caused symmetrical departures from veridicality which were consistent across spatial frequency, peaking at “victim” contrasts of ca. ±0.5. Both grating induction and contrast–contrast magnitudes decreased with reductions in inducing grating height, implying spatially extended mechanisms. With increasing inducing grating spatial frequency, however, the summation space-constant for grating induction decreased, whereas it increased for contrast–contrast.
Space-charge influence in a high-field ionization experiment double-peak formation
Authors: Walsh T. D. G. , Ammosov M. V. , Ilkov F. A. , Chin S. L.
Published: February 2023

Ar+ double peaks were observed in the time-of-flight spectra resulting from tunnel ionization of a xenon-argon gas mixture by an intense 10.6 µ laser. Experimental and theoretical analysis indicate that the double peaks are related to space-charge effects. Coulomb expansion of the two-component ion bunch produced in the laser focal region results in the formation of an external shell of Ar+ ions (due to its larger charge/mass ratio), surrounding the core of Xe+ ions (smaller charge/mass ratio). Subsequent cutting of Ar shell on the aperture diaphragm of the TOF mass-spectrometer produces two packets separated in space which correspond to Ar+ double peak observed.
Laser atomic mirror (LAM)
Authors: Korn Jeffrey , Bigelow N. P.
Published: February 2023

The main limitation with using a simple substrate as an atomic mirror is that the atoms have a tendency to adhere to the surface. To alleviate this problem, Cook and Hill1 proposed using the radiation force from an evanescent electric field to specularly reflect atoms from the surface.
Change of ions’ spontaneous emission by an intense laser beam
Authors: Cao H. , DiCicco D. , Suckewer S.
Published: February 2023

For atomic systems under strong influence of electromagnetic fields, the values of Einstein A and B coefficients have been observed to change from those of isolated atoms. However in our previous experiments which demonstrated the changes of A-coefficients, the self absorption of spontaneous emission was very strong and might the experimental result. In order to reduce the absorption drastically so that its effect can be neglected, we conducted a new experiment. In our new experiment, we measured the spontaneous emission from a very short discharge tube where the absorption was less than 4%. We also use a multichannel detector to monitor a number of spontaneous emission lines simultaneously. We observed that, as the incident photon flux increased, the intensity ratio of two spontaneous emission lines from the same upper level decreased. Any possible instrumental effect has been checked and eliminated. Therefore we can conclude that such observed decrement can only due to the change of Einstein A-coefficients.
Phase-dependent ionization by using an intense two-color light field with a calibrated phase difference
Authors: Schumacher D. W. , Weihe F. , Muller H. G. , Bucksbaum P. H.
Published: February 2023

We report the first study of Multi-Photon Ionization (MPI) using an intense two-color light field whose relative phase is known. The light field was produced by overlapped 80 ps pulses of 1.06 µm and .532 µm at various intensities and the phase difference was measured using non-linear mixing in KD*P. The light was focused into a chamber backfilled with Krypton gas, and the photoelectron energy spectrum was measured. We observed periodic variation of the MPI photoelectron peaks as a function of phase; moreover, the variation was seen to be asymmetric with respect to a change of sign in phase. The degree of asymmetry varied in a regular way as a function of intensity and peak energy. In general, the peak ionization rate was not observed to occur at the phase difference that produced the peak field. These effects were predicted for Hydrogen by Schaffer et al.,1 and are believed to be general in nature. We also report the effect of adding a small circular polarization component to the light field and the implications for a theory recently advanced by Corkum.2E Finally, we discuss the origin of these effects.
Controlling chaos in laser systems
Authors: Roy Rajarshi
Published: February 2023

Several laser systems have been studied in the past few years that display large, irregular fluctuations of the output intensity. Procedures to identify the chaotic origin of the fluctuations from measured time series of the intensity and to characterize the chaotic attractor will be outlined. Theoretical concepts and algorithms for control of chaotic dynamical systems and their application to chaotic lasers will be described. Recent experiments on Nd:YAG lasers with intracavity frequency doubling crystals1 and on Ndrfiber ring lasers2 have shown that it is possible to stabilize these systems to a steady state of the output intensity, as well as higher order periodic orbits consisting of complex periodic waveforms. Techniques for tracking the steady state as the pump excitation of the laser is changed will be described. Numerical computations based on laser models that reproduce aspects of the observed behavior will be discussed.
Intensity autocorrelation measurement as a detector of multimode effects and optical feedback in an AlGaAs diode laser
Authors: Westling L. A. , Thorpe J. T. , Giacoletti J. A.
Published: February 2023

Measurement of the intensity autocorrelation function of the output of an AlGaAs diode laser reveals that the presence of many small secondary modes which accompany the predominant mode in so-called “single-mode” diode lasers has a significant effect on the intensity of the laser. The total intensity of the output varies at frequencies due to mode beating between the main mode and the many tiny side modes. We have shown that these variations (at frequencies as large as 1000 GHz) are many times larger than that of the dynamical fluctuations due to noise processes in the laser.1 This is supported by a multimode-phase-diffusion-model which we developed from the theories of Henry2 and Agrawal.3 In contrast, the intensity of individual modes should fluctuate differently than that of the total output due to the partition of noise among the modes. The fluctuations of a single mode of a diode laser can thus be greater than that of the total intensity. We filter out the side modes with a monochrometer and measure the intensity autocorrelation function of the main mode alone. Our results also show that intensity autocorrelation measurements are a sensitive indicator of the presence and magnitude of external optical feedback.
On the validity of the coupled-oscillator model for laser array dynamics
Authors: Winful Herbert G. , Rahman Lutfur , Allen Sean
Published: February 2023

In a recent paper Xu, et al.1 reported the results of an experiment designed to test the coupled-oscillator theory of laser array dynamics.2 This model consists of a set of ordinary differential equations that use as basis fields the modes of the individual lasers and includes terms that couple the fields of adjacent lasers. In the paper of Xu et al., the authors claim that the coupled-oscillator model fails to describe their experimental results. Instead, they assert that the correct way to describe the array dynamics is to use as a basis set the array modes (supermodes) of the system of coupled lasers. They further claim that the coupled-oscillator model cannot describe the “instant” phase locking observed in their experiment.
Stability of polarized modes in a strongly anisotropic laser cavity
Authors: Paddon P. , Sjerve E. , Stephan G. M.
Published: February 2023

Previous calculations of the stability of the polarization modes of lasers, including their stability, bistability and curious catastrophes1,2 have invoked the mean field approximation. Since the cavity anisotropies and losses are approximated by distributed quantities, the polarization of the laser is the same throughout the cavity. In general then, one expects such an approximation to be valid only for cavities with small anisotropies. Such cavities are appropriately described as quasi–isotropic. We have succeeded in breaking this mean field approximation by propagating a plane wave around a linear cavity with strong optical anisotropies and a saturable gain medium. The calculations allow for the modification, of the saturation induced anisotropy, due to distinct states of polarization for the forward and backward propagating fields. Results are presented both for strongly anisotropic cavities and for quasi-isotropic cavities where mean field and non mean field calculations may be compared. This work was supported by the Natural Sciences and Engineering Research Council of Canada and the Province of Ontario through the Ontario Laser and Lightwave Research Centre.
High-temperature ceramic splice for sapphire optical fiber
Authors: Zhou Shaomin
Published: February 2023

Sapphire optical fiber application has been limited by its length, especially in blackbody optical fiber temperature sensor applications.1-3 The new ceramic splice, made of zirconia ceramic by sintering at 1400°C, can greatly extend the fiber length. The splice material bulk has a low porosity, high strength, and works through sharp temperature cycles compare with previous works.3 The equivalent emissivity of this junction is smaller than 0.15, which make this splice a practical device. Thermal radiation from this junction is guided away from the fiber gaps with an internal alignment sleeve. By applying several splices, the length of sapphire fibers can reach several meters. In a temperature differential of 300°C between the sensor head and the splice, the sapphire fiber temperature sensor can achieve a temperature reading stability of 0.5°C at 1000°C. This technology is also applicable for other ceramic connections used in a harsh temperature environment.
Excess noise imparted on a laser beam after it propagates through atomic-potassium vapor
Authors: Davis William V. , Kauranen Martti , Gehr Russell J. , Nagasako Elna M. , Boyd Robert W.
Published: February 2023

We have observed that a single laser beam that has propagated through an atomic potassium vapor can acquire excess noise. In particular, we find that even if the incident laser beam is shot noise limited, the transmitted laser beam contains noise in excess of its shot noise limit. We interpret this observation in terms of the amplification of vacuum sidemodes of the incident laser beam through forward four-wave mixing processes. These amplified sidebands then beat with the incident laser beam at the photodetector to create excess noise. The excess noise is maximum when the laser frequency is detuned from the potassium resonance by approximately one linewidth on either side of the resonance. We are presently developing a quantitative theoretical model to describe the process that produces this excess noise. We believe that this excess noise can degrade the noise properties of any nonlinear optical interaction that utilizes atomic vapors.
Photon-statistics dependence of single-atom absorption
Authors: Kochan P. , Carmichael H.J.
Published: February 2023

Under usual laboratory conditions the absorption of a beam of light by a dilute two-level medium depends on the intensity and spectrum of the incident light. If the incident photon flux is small compared to the decay rate of the absorber’s excited state, saturation effects can be neglected and only the spectrum of the light is important; thus, weak-field absorption depends only on the firstorder correlation function of the incident light. This result relies, however, on a requirement that the incident beam cross-section be much larger than the absorption cross-section of an atom. Then individual atoms act as low efficiency scatterers and the statistics of the scattering process is governed by the law of large numbers applied to many scattering sites. In contrast, if it is arranged that just one atom significantly absorbs (scatters) a beam of photons, correlation functions of the incident light beyond the first-order must be considered. For a beam that is focused within an absorption cross-section, we might naively predict that every photon will be scattered and none transmitted. In fact, even for a very weak beam there is a finite probability for two photons to arrive at the atom within the excited state lifetime, and in this event at least one of them will be transmitted (statistical saturation). In this paper we calculate the transmitted photon flux for a weak beam of photons focussed strongly onto a single, resonant two-state atom. We study the dependence of the transmitted flux on the statistics of the incident photons. Photon beams derived from sources of coherent, chaotic, squeezed, coherent-antibunched, and broadband-antibunched light are considered. our calculations are based on a recently developed theory of cascaded open systems,1,2 and serve to illustrate the usefulness of this theory.
Numerical analysis of overlay planar prisms on waveguides
Authors: Kim Jinkee , Kenan Richard P.
Published: February 2023

The planar prism has been considered as a passive component for high-density integration of optical devices. It may be fabricated by evaporating Si3N4 on a glass waveguide or grafting a semiconductor overlay on a dielectric waveguide. The planar prism is analyzed using a modified Suchoski’s exact numerical method,1 including the case when the input beam is at oblique incidence to the endface of the prism. The Gauss-Legendre integral method is adopted instead of Suchoski’s Simpson’s rule approximation to discretize the continuous radiation modes. This method reduces the calculation time, which allows us to select a denser nodal set for the more important spectral region. In order to get a large-angle directional change of the beam, the critical angle at the endface should be less than 45°. As the thickness of the overlay increases, both the critical angle and the power of the fundamental mode decrease. Thus, an optimal thickness can be obtained when the power in the radiation modes is minimized. Numerous calculations have been performed with various thicknesses and indices of the overlay and main film. As an application, a finite-impulse-response filter is presented.
High-efficiency Gaussian-beam waveguide grating couplers
Authors: Roncone Ronald L. , Li Lifeng , Bates Keith A. , Burke James J.
Published: February 2023

High efficiency, Gaussian beam input and output waveguide grating couplers are of substantial interest for future applications in optical data storage and guided wave sensors. We have demonstrated that variable depth gratings may be utilized to shape the out-coupled beam profile, and thus enable Gaussian beam out-coupling1 and optimal in-coupling. Additionally, we have demonstrated that the branching ratio of a constant groove depth grating coupler may be enhanced by depositing a high reflectivity broadband dielectric stack above (or below) the grating/waveguiding region.2 The stack reflects the portion of the out-coupled light diffracted toward the cover (or substrate) region, and redirects it to constructively add with the portion of the out-coupled light originally diffracted into the substrate (or cover) region. This produces output coupling efficiencies into a single channel approaching 100%. In this presentation, we will combine the variable depth grating with the high branching ratio design concept to demonstrate a high efficiency Gaussian beam input/output coupler. The modeling, fabrication, and performance characteristics (input coupling efficiency, branching ratio, and output beam profile) of fabricated devices will be presented.
Fast image visibility enhancement based on active polarization and color constancy for operation in turbid water
Authors: Liu Luping , Li Xin , Yang Jianmin , Tian Xinliang , Liu Lei
Published: February 2023

Vehicles operating in a water medium sometimes encounter harsh conditions with high turbidity and low scene illumination, making it challenging to obtain reliable target information through optical devices. Although many post-processing solutions were proposed, they are not applicable to continuous vehicle operations. Inspired by the advanced polarimetric hardware technology, a joint fast algorithm was developed in this study to address the above problems. Backscatter attenuation and direct signal attenuation were solved separately by utilizing the revised underwater polarimetric image formation model. A fast local adaptive Wiener filtering method was used to improve the backscatter estimation by reducing the additive noise. Further, the image was recovered using the fast local space average color method. By using a low-pass filter guided by the color constancy theory, the problems of nonuniform illumination caused by artificial light and direct signal attenuation were both addressed. The results of testing on images from laboratory experiments showed improved visibility and realistic chromatic rendition.
Three-electrode germanium-on-silicon avalanche photodiode array
Authors: Liu XiaoBin , Li XueTong , ZHi ZiHao , Li YingZhi , Chen BaiSong , Xie QiJie , Na Quanxin , Li XueYan , Guo PengFei , Gao FengLi , Lo GuoQiang , Kang BoNan , Song Junfeng
Published: February 2023

In this Letter, we report a bridge-connected three-electrode germanium-on-silicon (Ge-on-Si) avalanche photodiode (APD) array compatible with the complementary metal-oxide semiconductor (CMOS) process. In addition to the two electrodes on the Si substrate, a third electrode is designed for Ge. A single three-electrode APD was tested and analyzed. By applying a positive voltage on the Ge electrode, the dark current of the device can be reduced, and yet the response of the device can be increased. Under a dark current of 100 nA, as the voltage on Ge increases from 0 V to 15 V, the light responsivity is increased from 0.6 A/W to 1.17 A/W. We report, for the first time to the best of our knowledge, the near-infrared imaging properties of an array of three-electrode Ge-on-Si APDs. Experiments show that the device can be used for LiDAR imaging and low-light detection.
Visible to near-infrared polarization-independent large-incidence-angle ultra-broadband absorber
Authors: wu yongchang , liu yue , Ma Wenzhuang , Chen Yushan , cheng yuyao , Li Degui , Liu Jing , gu yu
Published: February 2023

In this study, a novel ultra-broadband absorber is suggested and numerically analyzed to demonstrate that the suggested absorber can attain an average absorbance of 98.6% in the visible to near-infrared wavelength range(496–2100 nm). The structure of the proposed new ultra-wideband absorber consists of five thin films of silicon dioxide (SiO2), iron (Fe), magnesium fluoride (MgF2), chromium (Cr) and aluminium (Al). We have examined the structure’s electromagnetic field intensity distribution at numerous selected optical wavelengths and the influence of various structural parameters on the absorption performance of the absorber to offer a physical mechanism underlying the ultra-broadband absorption effect. Furthermore, in the presence of high-performance absorption, the structure has the effect of stabilizing absorption at large angles of incidence and is polarization independent at vertical angles of incidence. The study also assesses the solar absorption capability of this structure, indicating that the structure has potential applications in solar absorption, like solar energy collection and conversion, solar power generation, and thermal emitters.
Measures to assess quality of postnatal care: A scoping review
Authors: Galle Anna , Moran Allisyn C. , Bonet Mercedes , Graham Katriona , Muzigaba Moise , Portela Anayda , Day Louise Tina , Tuabu Godwin Kwaku , Silva Bianca De Sá é , Moller Ann-Beth
Published: February 2023

High quality postnatal care is key for the health and wellbeing of women after childbirth and their newborns. In 2022, the World Health Organization (WHO) published global recommendations on maternal and newborn care for a positive postnatal care experience in a new WHO PNC guideline. Evidence regarding appropriate measures to monitor implementation of postnatal care (PNC) according to the WHO PNC guideline is lacking. This scoping review aims to document the measures used to assess the quality of postnatal care and their validity. The review was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR). Five electronic bibliographic databases were searched together with a grey literature search. Two reviewers independently screened and appraised identified articles. All data on PNC measures were extracted and mapped to the 2022 WHO PNC recommendations according to three categories: i) maternal care, ii) newborn care, iii) health system and health promotion interventions. We identified 62 studies providing measures aligning with the WHO PNC recommendations. For most PNC recommendations there were measures available and the highest number of recommendations were found for breastfeeding and the assessment of the newborn. No measures were found for recommendations related to sedentary behavior, criteria to be assessed before discharge, retention of staff in rural areas and use of digital communication. Measure validity assessment was described in 24 studies (39%), but methods were not standardized. Our review highlights a gap in existing PNC measures for several recommendations in the WHO PNC guideline. Assessment of the validity of PNC measures was limited. Consensus on how the quality of PNC should be measured is needed, involving a selection of priority measures and the development of new measures as appropriate.
Noise characteristics in spaceflight multichannel EEG
Authors: Fiedler Patrique , Haueisen Jens , Alvarez Ana M. Cebolla , Cheron Guy , Cuesta Pablo , Maestú Fernando , Funke Michael
Published: February 2023

The cognitive performance of the crew has a major impact on mission safety and success in space flight. Monitoring of cognitive performance during long-duration space flight therefore is of paramount importance and can be performed using compact state-of-the-art mobile EEG. However, signal quality of EEG may be compromised due to the vicinity to various electronic devices and constant movements. We compare noise characteristics between in-flight extraterrestrial microgravity and ground-level terrestrial electroencephalography (EEG) recordings. EEG data recordings from either aboard International Space Station (ISS) or on earth’s surface, utilizing three EEG amplifiers and two electrode types, were compared. In-flight recordings showed noise level of an order of magnitude lower when compared to pre- and post-flight ground-level recordings with the same EEG system. Noise levels between ground-level recordings with actively shielded cables, and in-flight recordings without shielded cables, were similar. Furthermore, noise level characteristics of shielded ground-level EEG recordings, using wet and dry electrodes, and in-flight EEG recordings were similar. Actively shielded mobile dry EEG systems will support neuroscientific research and neurocognitive monitoring during spaceflight, especially during long-duration space missions.
Atopic dermatitis and risk of gastroesophageal reflux disease: A nationwide population-based study
Authors: Lee Seung Won , Park Jiwon , Kim Hayeon , Jung Yong Woo , Baek Yoo Sang , Lim Yejee , Kim Kyungim
Published: February 2023

Background

As atopic dermatitis (AD) has been found to be related to various comorbidities as well as substantial patient burden, questions of a possible relationship between AD and nonallergic diseases beyond allergic diseases have also been raised.

Objective

The aim of this nationwide matched cohort study was to evaluate whether AD would increase the development of gastroesophageal reflux disease (GERD).

Methods

Patients diagnosed with AD were identified from the National Health Insurance Service-National Sample Cohort (NHIS-NSC) 2.0 database in South Korea from 2002 to 2015. Finally, 9,164 adults with AD (≥20 years old) and age, sex, household income, region of residence, disability, and baseline year-matched 9,164 controls were included in the analysis. Hazard ratio (HR) with 95% confidence interval (CI) for the development of GERD was estimated using a Cox proportional hazard regression model.

Results

Overall, 12.3% of the patients in the AD group developed GERD, whereas 10.4% of the individuals in the control group developed GERD. The results of the adjusted model revealed that patients with AD had a significantly increased risk of developing GERD (adjusted HR, 1.15; 95% CI, 1.06–1.26) compared with the matched controls. Increased risk of developing GERD was consistent in subgroup analyses by sex or age groups under 60 years old as well as all the sensitivity analyses performed.

Conclusions

This study suggested that appropriate management should be considered in adults with AD to prevent GERD, because AD was found to be associated with an increased risk of subsequent GERD.
First report of acanthocephalan parasite in wild-caught Asian vine snake (Ahaetulla prasina) in Indonesia
Authors: Yudhana Aditya , Praja Ratih Novita , Edila Ryanka
Published: February 2023

Background and Aim: Exotic pet snakes are more susceptible to infection, especially parasitic helminths than wild-caught. There is no comprehensive report on the prevalence of acanthocephalan parasite infection in Indonesian snakes. Therefore, this study aimed to estimate the prevalence rate and to identify the acanthocephalan infection in wild-caught Asian vine snake (Ahaetulla prasina) from the Mojokerto District, East Java, Indonesia.

Materials and Methods: A total of 60 snakes were collected from the local sellers in the Mojokerto District, East Java, Indonesia. Then, snakes were euthanized and necropsied to observe various predilections of acanthocephalan larval stage (cystacanth). Morphological identification of the cystacanth was conducted using the carmine staining method and microscopic examination.

Results: Acanthocephalan infection was recorded with a high prevalence rate of 80.06%. A total of 696 cystacanths were examined from the muscle, subcutaneous tissues, and visceral with 32.90, 16.37, and 50.71% intensity rates, respectively.

Conclusion: Acanthocephalan prevalence rate was recorded at 80.06% in this study. Constant disease monitoring is necessary, considering wild-caught Asian vine snakes were susceptible host and lack of data regarding parasitological surveys. Therefore, further studies are needed in new areas and various species of wild-caught snakes in Indonesia, because of the potential of parasitic helminth transmission between snake and other reptiles.
A Study on the Standardization of Disaster Prevention Projects to Climate Change Response
Authors:   Crisis and Emergency Management: Theory and Praxis, Kim So Yeon , Kim Young Kyu
Published: February 2023

Recently, the intensity of disasters is increasing as heavy rainfalls due to climate change, and fundamental measures are required. In this study, the limitations of the disaster prevention management system were reviewed, and legal plans by each ministries and overseas cases were analyzed. As a results, it was intended to present a comprehensive plan for work in disaster prevention aimed at protecting life and property and a plan to manage the cooperative system of each ministries. In order to solve the multiple risk factors in a lump, comprehensive work in disaster prevention is required. it is necessary to establish and operate a headquarters to promote this, and a working-level group for efficiency such as adjusting the timing of budget input. However in terms of disaster prevention, it was suggested to have a regional council so that sustainable measures could be established, not just one —time. For a safety system that local residents can feel, it was classified into urban, agricultural, mountain, coastal and complex areas, and structural and non —structural measures suitable for regional characteristics were proposed. Through this study, it is expected to contribute to the unification of the aspect of work in disaster prevention.
Comparative evaluation of the efficacy and safety of intra-articular administration of hyaluronic acid and glucocorticoids in the complex therapy of osteoarthritis
Authors: Peshekhonova L. K. , Kotelnikova T. E. , Peshekhonov D. V. , Kalashnik G. A.
Published: February 2023

Improving the treatment of knee (KN) osteoarthritis (OA) remains an urgent problem.Objective: to compare the efficacy and tolerability of intra-articular (i/a) administration of long-acting glucocorticoids (GCs) and Armaviscon®Forte and Armaviscon®Platinum hyaluronates in patients with knee OA.Material and methods. From November 2019 to April 2022, we examined and treated 60 patients (26 men and 34 women, mean age 41.32±3.71 years) suffering from primary KN OA. Study participants were randomly divided into three groups of 20 patients each. In the 1st group, a longacting GCs in combination with a local anesthetic was administered once i/a into the KN, in the 2nd – Armaviscon®Forte 2.3%, and in the 3rd – Armaviscon®Platinum 3%.Patients were examined at baseline, on the 14th and 60th day after a single injection of the drug. The intensity of pain was assessed on a visual analog scale (VAS), the Lequesne index, the KOOS, WOMAC, and EQ-5D questionnaires were used. When studying tolerability, the number of adverse reactions (ARs) was taken into account.Results. By the end of the observation period in the study groups, there was a decrease in the severity of pain and an increase in functionality with positive dynamics of the Lequesne and WOMAC indices. Both hyaluronic acid drugs had a positive effect on the functional state of the joints according to KOOS, improved the quality of life according to EQ-5D. The need for non-steroidal anti-inflammatory drugs in patients of the 2nd and 3rd groups decreased down to their complete cancellation. No adverse events requiring discontinuation of therapy have been reported. The advantage of i/a administration of hyaluronates in comparison with long-acting GCs was shown.Conclusion. In real clinical practice, in patients with symptomatic OA, i/a administration of hyaluronates allows obtaining more favorable results than the use of long-acting HA.
Techno-Economic and Environmental Feasibility Study of a Hybrid Photovoltaic Electrification System in Back-up Mode : A Case Report
Authors: Hounkpatin Henri Wilfried , Donnou Hagninou Elagnon Venance , Chegnimonhan Victorin Kouamy , Inoussa Latifath , Kounouhewa Basile Bruno
Published: February 2023

In developing countries, institutions that have to operate continuously during daylight hours consume relatively large amounts of electrical energy for lighting and air conditioning, leading to high bills. Untimely power cuts lead to a fluctuation in the voltage delivered by the conventional network, which induces the malfunctioning of electrical equipment and the discontinuity of judicial work. The use of photovoltaic solar energy makes it possible, on the one hand, to ensure continuity of service in the event of damage, and on the other hand to stem greenhouse gas emissions through the sustainable nature of this energy.  Solar installations also make it possible to maintain the permanent power supply in the event of instability of the electrical network and to correct the voltage variations undergone by the energy equipment. Thus, this  (case) study  is based on the energy balances evaluated on the buildings of the jurisdiction of the city of Kandi (Benin) to propose effective solutions of electrification according to six (6) technical scenarii. Each component of the back up system has been sized considering technical requirements and an economic and environmental study has been carried out. The results indicate that the integrated scenario 6 of a "back-up" system with a solar fraction of up to 37% (49.5 kWc) seems to be the most suitable conf iguration for the current needs of the Kandi jurisdiction due to the shortest time to return on investment (5.1 years) and the maximum annual savings generated (33,674 USD). The environmental impact study has made it possible to determine the CO2  emissions avoided as well as the contribution of Carbon credits that this jurisdiction would reap has been evaluated at 115.8 tCO2  equivalent, or 10.6 hectares of forest carbon preserved over the life of the project. This configuration is therefore strongly recommended for a sustainable energy mix in the jurisdictions of Benin as well as for administrative or similar sites where electricity consumption is maximum during the day.
A corrugated and lens based miniaturized antipodal Vivaldi antenna for 28 GHz and 38 GHz bands applications
Authors: Dixit Amruta S. , Kumar Sumit , Abegaonkar Mahesh
Published: February 2023

The paper presents a dualband and compact antipodal Vivaldi antenna (AVA) array by using a dielectric lens (DL) and corrugations for 5G applications. The proposed novel antenna provides very high efficiency and it alleviates beam titling very effectively. Its efficiency is in the range of 95.93%–97.52% whereas the H plane beam titling is

±

1
°

$\pm 1{}^{\circ}$

over most of the frequency range. The antenna frequency response is improved by incorporating corrugations which results in the antenna miniaturization. The designed AVA array size is 2.86 × 3.58 × 0.06

λ
g

3

${{\lambda }_{g}}^{3}$

(for lower guided frequency). The proposed dualband antenna operates from 24.17 GHz to 29.37 GHz and 30.76 GHz to 40.58 GHz. These frequency bands cover 28 GHz and 38 GHz bands of 5G communications. Next, the front-to-back ratio is improved significantly which further results in the gain enhancement. Also, the grooves in the feeding network minimize reverse power reflections. The radiation pattern is stable and it shows that the designed antenna is a directional antenna. The antenna is designed, simulated, and tested by using a network analyzer and anechoic chamber. The testing and simulated results indicate that the proposed AVA array is the best candidate to integrate it in 5G devices.
The EBM+ movement
Authors: Wilde Michael
Published: February 2023

In this paper, I provide an introduction for biostatisticians and others to some recent work in the philosophy of medicine. Firstly, I give an overview of some philosophical arguments that are thought to create problems for a prominent approach towards establishing causal claims in medicine, namely, the Evidence-Based Medicine (EBM) approach. Secondly, I provide an overview of further recent work in the philosophy of medicine, which argues that mechanistic studies can help to address these problems. Lastly, I describe a novel approach for establishing causal claims in medicine that has been informed by this recent work in the philosophy of medicine, namely, the EBM+ approach.
Congenital hypothyroidism in children with eutopic gland or thyroid hemiagenesis: prognostic factors for transient vs. permanent hypothyroidism
Authors: Bontemps Sylvie Hélène , Legagneur Carole , Guéant-Rodriguez Rosa-Maria , Remen Thomas , Luc Amandine , Renard Emeline
Published: February 2023

Objectives

More than one third of children with congenital hypothyroidism (CH) and thyroid gland in situ (or eutopic gland) have transient hypothyroidism. It remains difficult to determine early on whether hypothyroidism will be transient which may cause overtreatment and its complications in these children. Our primary aim was to determine prognostic factors for transient hypothyroidism in children with congenital hypothyroidism and eutopic gland or thyroid hemiagenesis.

Methods

We retrospectively reviewed medical records of 111 children, born between 1996 and 2017, diagnosed with congenital hypothyroidism and eutopic gland or hemiagenesis and treated at the Nancy Regional and University Hospital.

Results

Fifty four infants (48.6%) had permanent congenital hypothyroidism (PCH) and 57 (51.4%) transient congenital hypothyroidism (TCH). Prognostic factors for TCH included prematurity, twin pregnancy, low birth weight and Apgar score <7, while low FT3 at diagnosis, maternal levothyroxine treatment, a family history of thyroid dysfunction and TSH ≥10 mUI/L while receiving treatment were associated with PCH. Knee epiphyses on X-ray at diagnosis were absent only in children with PCH. The median levothyroxine dose during follow-up was significantly lower in the TCH group compared to the PCH group. A levothyroxine dose of ≤3.95, ≤2.56, ≤2.19 and ≤2.12 μg/kg/day at 6 months, 1, 2 and 3 years of follow-up, respectively, had the best sensitivity-to-specificity ratio for predicting TCH.

Conclusions

Even though it remains difficult to predict the course of hypothyroidism at diagnosis, we were able to identify several prognostic factors for TCH including perinatal problems and lower levothyroxine requirements that can guide the physician on the evolution of hypothyroidism.

Clinical Trial Registration Number: NCT04712760.
Front vowels of Spanish: A challenge for Chinese speakers
Authors: Cao Yongfa , Font-Rotchés Dolors , Rius-Escudé Agnès
Published: February 2023

This research proposes to define the timbre of front vowels [e] and [i] in the spontaneous speech of the Spanish interlanguage spoken by Chinese people and to determine the convergent and divergent features of Peninsular Spanish. Variables such as gender, level of Spanish proficiency and the (a)tonicity of the vowels will also be assessed to see the extent to which these factors influence the pronunciation of the learners. A corpus of 1,489 front vowels produced by 36 Chinese speakers and a corpus of 420 vowels produced by 79 Spanish speakers were used for this study. The mean F1and F2values were calculated for each vowel. According to the statistical analysis of spontaneous speech, the interlanguage and the target language are similar in that the sounds [i] and [e] are significantly different, the atonic and tonic [i] show no significant differences and the tonic [e] is more open than the atonic [e] in both genders. However, the interlanguage diverges more from the target language because the timbre of the front vowels is more dispersed, that of [i] is more closed and fronted and that of [e] is more open and fronted, in both males and females, tonic and atonic. Finally, the study reveals that the level of language proficiency and tonicity are factors that influence the acquisition of pronunciation.