bluuebunny/crossref_metadata_2025 huggingface dataset:
Dispersion of Modes Guided in Photonic Crystal Fibres
Authors: Mogilevtsev D. , Birks T. A. , Russell P. St.J.
Published: February 2023

The photonic crystal fibre (Fig. 1) is a pure silica structure with a solid core surrounded by a hexagonal array of sub-micron air capillaries - the photoniccrystal. One of the unusual properties of the fibre is that it can be single-mode at all wavelengths, as has been confirmed experimentally over the range 337- 1550 nm[1]. This behaviour is due to the unusual wavelength dependence of the effective refractive index of the fibre's photonic crystal cladding[2], which may be expected to have interesting consequences for the guided mode's dispersion. Unfortunately, the simple effective index model is not capable of calculating modal properties like propagation constants, group velocity dispersion and field distributions.
Laser Resonators Containing Diffractive and Microoptic Components
Authors: Leger James R. , Makki Siamak
Published: February 2023

Virtually all current laser systems employ conventional flat or spherical optical components to form the optical resonator. With the dramatic advances in microfabrication technology, it is now possible to make diffractive and microoptic elements with sufficient precision for use in laser resonators. These new elements can be used as end mirrors and intracavity filters with arbitrary surface figures, greatly expanding the design space of laser resonators. In this talk, we will review the state-of-the-art for these unconventional laser resonators.
Surface-Emitting Lasers Coupled to Extended Cavities with a Phase Plate: Dependence on the Orientation of the Plate Axes
Authors: Ginovart F. , Chartier T. , Stéphan G. , Besnard P. , Robert F
Published: February 2023

A Vertical-Cavity-Surface-Emitting Lasers (VCSEL) submitted to an optical external feedback through a quarter-wave plate could have its intensity self-modulated [1] in the microwave range. One effect of the plate is to impose the eigen axes of the coupled cavity [2], When the axes of the inserted plate are at 45° with respect to the laser ones, the beating between two spatially-separated combs of modes, frequency-separated by c/4L, can be observed along the axes of the bare laser. Introducing a vectorial Airy function, we show here that the effect of a rotation of the quarter-wave plate is to shift one comb of modes with respect to the other one and enables to control the longitudinal modes of the external cavity The beating can thus generate a frequency lower or higher than c/4L depending on the mode selection. This shift is related to the inner birefringence e inside the laser cavity. This small birefringence is boosted by the high reflectivity of the laser output mirror.
Absolute distance measurements using a noisy interferometer
Authors: Ben-Chorin Moshe , Chuartzman Silvia , Prior Yehiam
Published: February 2023

The spectrum of white light passing through a Michelson interferometer develops a sinusoidal modulation, the frequency of which is determined by the path difference between the interferometer arms. Dispersive white light interferometry is capable of measuring relatively large distances (hundreds of µm) with high precision, and without moving parts. However, as with all interferometric methods, it is very sensitive to phase noise arising from such factors as vibrations or air turbulence. The random phase jumps reduce the visibility of the white light fringes. This limitation imposes stringent conditions upon the stability of the interferometer, and its applicability to field measurements is thus restricted.
Direct holographic shape measurement using digitalized Light-in-Flight recording by holography
Authors: Carlsson Torgny , Nilsson Bengt
Published: February 2023

Light-in-Flight recording by holography is a technique for direct visualization of the propagation of a short light pulse when it is e.g. intersecting a 3D-shaped object. This is achieved by letting the reference beam be delayed in comparison to the object beam along the holographic plate. As a result, different intersections are seen from different points of the hologram and can be put together using an image processing system in order to measure the 3D-shape [1]. The delay is usually achieved by letting the reference beam be incident on the hologram at a grazing angle. This requires a high resolution recording media such as a photographic emulsion. In order to make the result directly achievable to the image processing system, it would be preferable to record the hologram directly in a CCD-array. However, the limited resolution of the CCD-array requires that the reference- and object beams are almost parallel and perpendicular incident on the array.
Light-Induced Charge Transport Processes in Photorefractive Crystals
Authors: Buse K.
Published: February 2023

Inhomogeneous illumination of photorefractive materials redistributes charge, space-charge fields build up and modulate the refractive index via the electrooptic effect. No development or further processing is required. This effect enables promising applications in the fields of solid state phase conjugation, image processing and volume holographic data storage. Insights into the light-induced charge transport processes are the key for successful material engineering [1]. Recently photoconductivity measurements with continuous wave and pulsed excitation, absorption measurements, X-ray photoelectron spectroscopy, neutron activation analysis, investigations with non-steady-state photocurrents and Hall measurements are used to characterize strontium-barium niobate crystals (Sr0.61Ba0.39Nb2O6, SBN) doped with cerium. A full set of charge transport parameters of a photorefractive crystals has been obtained for the first time.
Four fold improvement of the photorefractive time constant of BaTiO3:Rh by oxidation
Authors: Huot N. , Pauliat G. , Jonathan J.M.C. , Roosen G. , Scharfschwerdt R. , Schirmer O.F. , Rytz D.
Published: February 2023

Our spectroscopic studies have shown without ambiguity that the three charge states Rh3+, Rh4+, Rh5+ are responsible at 1.06 µm for the optical absorption and charge redistribution through hole photoconductivity in rhodium doped barium titanate [1]. From this three charge state model, we solved the charge transfer equations and used the obtained results to characterize as grown samples at 1.06 µm through induced absorption and two-wave mixing experiments [2]. A major feature is that the photoexcitation cross section from Rh5+ to the valence band is about 75 times larger than the one from Rh4+. These previous results suggest that the photorefractive rise time could be decreased by lowering the Fermi level by oxidation. This removes the positive charges of oxygen vacancies which compensate the negative charges of acceptors being present in the crystal. Compensation is then achieved by the positive charges of holes captured at Rh3+ (forming Rh4+) or at Rh4+ (forming Rh5+).
Gain cross section measurements on the 2.8 µm laser transition of Er3+ doped BaY2F8 single crystal
Authors: Labbé C. , Doualan J.L. , Girard S. , Moncorgé R. , Thuau M.
Published: February 2023

The ~2.8 µm laser transition of Er3+ ions is interesting for medical application. The transition takes place between the two excited states 4I11/2 and 4I13/2. In the fluoride crystals this emission is efficient due to low nonradiative processes between these two levels. The Er3+:BaY2F8 [1] is one of the most interesting crystals for 2.8 µm emission because the lifetime ratio between 4I11/2 and 4I13/2 is closed to one and the phonon energy is low compared to LiYF4. Some strong excitation transfer processes make difficult the prediction of the efficiency by a population rate equations model. It’s important to know the gain cross section and population inversion rate to predict the laser properties.
Generation of intense 20fs pulses around 400nm and Raman down-conversion in gas-filled hollow waveguides
Authors: Korn G. , Dühr O. , Nibbering E. T. J. , Nazarkin A.
Published: February 2023

For different short pulse spectroscopy experiments as well as high intensity physics investigations extremely short intense tunable pulses are needed in the uv or vuv.
Performance of a diode-pumped 1.4 W Tm:GdVO4 microchip laser at 1.9μm.
Authors: Wyss Chr. , Lüthy W. , Weber H. P. , Vlasov V. I. , Zavartsev Yu. D. , Studenikin P. A. , Zagumennyi A. I. , Shcherbakov I. A.
Published: February 2023

GdVO4 as a host for Thulium has several advantages for diode pumping in comparison with YAG. The absorption cross section of Thulium in GdVO4 is considerably stronger and broader than in YAG and the spectrum is shifted closer to the emission wavelength of commercially available AlGaAs laser diodes. The broad emission spectrum (1.9 μm - 2.1 μm) allows for tuning the laser wavelength. Furthermore, the large thermal conductivity of GdVO4 (10 W/mK) is very favourable for efficient cooling of the crystal.
Absolute frequency stabilization of a continuous-wave optical parametric oscillator to sub-kHz level
Authors: Bencheikh K. , Storz R. , Schneider K. , Jäck K. , Lang M. , Schiller S. , Mlynek J.
Published: February 2023

C.w. Optical Parametric Oscillators (OPOs) have recently undergone significant improvements in both emission range and reliability. One of the important step towards high resolution spectroscopy using OPOs is a better stabilization of their frequencies to instabilities level as small as the widths of the transitions to be investigated.
Thermal Waveguiding induces Polarization Switching in Vertical-Cavity Surface-Emitting Lasers
Authors: Panajotov K. , Ryvkin B. , Danckaert J. , Peeters M. , Veretennicoff I. , Thienpont H.
Published: February 2023

One of the most intriguing aspects of Vertical-Cavity Surface-Emitting Lasers (VCSEL's) lies in their polarization behaviour, which differs from that of edge-emitting lasers due to the lack of a dominating polarization selection mechanism in the quasi cylindrically symmetric structure. One explanation for the observed polarization switching is of a thermal nature and attributes the switching to the shift (caused by the current heating) of the material gain spectral profile relative to the cavity resonances for the two frequency-split polarization modes1. This model seems to be contradicted by recent experiments, which reported polarization switching at constant active layer temperature (by applying low duty-cycle short pulses on a constant bias level). These authors propose an alternative model based on the spin dynamics between magnetic sublevels in the semiconductor active material2. Nevertheless, thermal effects are recognized to play an important role in the behavior of VCSEL's.
Aerosol sounding with lidar in UV and Near IR for IR transmission studies
Authors: Hågård Arne , Persson Rolf
Published: February 2023

The performance of IR sensors and particularly the attainable detection range against targets depends to a large extent on the atmospheric transmission. With the aim to provide data for the calculation of IR transmission in connection with test and evaluation of airborne IR sensors we perform measurements with a lidar. Backscatter from aerosols is measured at two wavelengths, 355 nm and 1.54 μm. Statistical analysis of data from earlier measurements with a ground based transmissometer (ref) has shown that values of the aerosol extinction coefficient at 0.55 and 1.7 μm can be combined to calculate the coefficient for thermal IR with fairly good accuracy. We therefore conclude that lidar returns at two different wavelengths, as obtained in our lidar, may provide data for the calculation of IR transmission at higher altitudes.
Ultrafast dynamics and modelling of Semiconductor Optical Amplifiers for WDM applications
Authors: Deveaud B. , Dupertuis MA , Hessler T. , Pleumeekers J. , Selbmann PE
Published: February 2023

We have developped a research program aimed at the study of the ultrafast dynamical properties of Semiconductor Optical Amplifiers (SOAs). This program is run in collaboration with the group of H. Melchior, and of H. Jaeckel in Zurich and the group of F. Devaux at Alcatel. Amongst the properties of these devices, we specifically study their possibilities in terms of switching and wavelength conversion. To this aim, we have developped a femtosecond setup which allows to probe the cross gain dynamics of the amplifiers. A cw beam is fed into the amplifier and is modified by a strong cross-polarized pump beam. The changes of the cw beam are then time resolved with 150 fs resolution in a non linear gate. Such a set-up corresponds to the configuration used for wavelength conversion, and has the great interest to provide at the same time the time resolution and the relative tunability of the two laser beams over a wide range.
Amplified Spontaneous Emission in Poly(Para-Phenylene) Ladder-Type Polymer
Authors: Stagira X , Cerullo G. , Nisoli M. , Zavelani-Rossi M. , De Silvestri S. , Lanzani G. , Graupner W. , Leising G.
Published: February 2023

The development of highly luminescent conjugated polymers is of great importance for promising applications in LEDs and "plastic" lasers. It was recently found that photoluminescence (PL) from polymer films under high optical excitation shows a strong line narrowing effect [1], Amplified spontaneous emission (ASE), superfluorescence, and exciton condensation are amongst the proposed mechanisms.
Ultraprecision grinding of optical components
Authors: Namba Y. , Takehara Y.
Published: February 2023

Grinding has been used in the optics industry as a typical figuring process for optical glass components. Conventional grinding requires a final polishing process for getting optical-quality surfaces. This paper present a new technology for making optical surfaces using ultraprecision grinding without a polishing process.
He-Hg+ and He-Cd+ Lasers
Authors: Vuchkov Nikolay K , Temelkov Krassimir A. , Sabotinov Nikola V.
Published: February 2023

Laser oscillation in ionized metal vapors in wide spectral range (from UV to IR) is known to date. Different type of gas discharges are used for metal ion laser excitation - continuous wave and pulsed positive column discharge; continuous wave and pulsed hollow cathode discharge; high frequency discharge and electron beam excitation. Each of these discharges has its advantages and drawbacks. An investigation is needed in metal vapor ion laser development involving new methods for excitation of this laser class.
Ti-diffusion in sapphire for active and passive waveguide devices
Authors: Hickey L M B , Quigley G R , Wilkinson J S , Moya E G , Moya F , Grattepain C
Published: February 2023

Interest in aluminium oxide as a material for integrated optic devices is increasing. Recent successes include the realisation of amplification in Er doped A12O3 waveguides deposited on Si/SiO2 substrate1 and miniature Ti:sapphire lasers in both epitaxially grown slab waveguides2 and thermally diffused channel waveguides3.
Cr4+:Y3Al5O12 and Cr4+:Gd3Ga5O12 laser waveguide structures fabricated by pulsed laser deposition
Authors: Hasegawa Tetsu , Adachi Kyoichi , Machida Akihiko , Fukaya Sachiyo , Obara Minoru , Kumagai Hiroshi , Midorikawa Katsumi
Published: February 2023

Optical waveguide structures have great advantages over bulk crystals, such as optical confinement, compactness and device integration capability. Recently, chromium-doped Y3Al5O12 (Cr4+:YAG), Gd3Ga5O12 (Cr4+:GGG) crystals have attracted much attention as a solid-state waveguide tunable laser at 1.35 μm - 1.45 μm and a saturable absorber around 1.0 μm. Pulsed laser deposition (PLD) technique is quite suitable for fabrication of the Cr4+:YAG, Cr4+:GGG thin films, because we can easily control the valence state of the Cr ion in the Cr4+:YAG, Cr4+:GGG thin films. In this study, we have fabricated high optical quality Cr4+:YAG and Cr4+:GGG thin films.
Design of High Power Tapered Waveguide Semiconductor Lasers
Authors: Williams K.A. , White I.H. , Penty R.V. , Robbins D.J. , Lewandowski J.J.
Published: February 2023

A two-dimensional dynamic beam propagation model [1] has been developed to isolate mechanisms for far field broadening and engineer improved laser beam quality in high brightness tapered waveguide lasers. These low beam divergence, high brightness devices have many possible applications, including low-cost pumps for fibre amplifiers and lasers. Spatially resolved thermal models have so far been used to describe the role of hot spots on filamentation in tapered waveguide amplifiers [2]. Here we show theoretically for the first time that the far field narrows with good suppression of higher order modes for an appropriate temperature rise, without significant power penalty, in agreement with experiment.
Factors determining Optimum HBr flow rate in Copper HyBrID Lasers
Authors: Mildren Richard P , Piper James A
Published: February 2023

The copper HyBrID laser is a variant of conventional elemental copper vapour lasers (ECVLs) which offers improved output performance and a number of practical advantages. The efficiency (1-3%), pulse repetition frequency (~20 kHz) and specific output powers are 2-3× that of ECVLs[1], and moreover, a markedly higher fraction of total output power can be extracted with near diffraction limited beam quality when using high magnification axial unstable resonators (>60%[2]). Lasant Cu atoms are produced in the discharge of the Cu HyBrID by dissociation of copper bromide that is formed by the reaction of solid copper pieces placed along the floor of the discharge tube with a continuous flow of HBr (and neon) gas. Though practical advantages arise with this method of copper seeding, including an operating tube wall temperature below the melting point of silica and output power that is fairly insensitive to tube wall temperature over the range 500-850°C (cf ECVLs 1500-1550°C), a serious disadvantage arises due to the requirement that high output power only occurs within a narrow range of HBr flow rates. A gas-handling system that provides careful metering of HBr gas is required which is not commercially attractive as HBr is toxic and highly corrosive.
High pulse repetition rate CuBr-laser
Authors: Evtushenko G. , Klimkin V. , Sukhanov V. , Fedorov. V.
Published: February 2023

Research into self-terminating metal vapor lasers has a tendency towards high laser pulse repetition rates (PRR’s). On the one hand, the production of PRR's between 0.1-1.0 MHz shows promise of further increase in the average power from this kind of lasers and, on the other hand, opens up fundamentally new possibilities for their applications.
Efficient collisional high-pressure lasers with ionizing pumping
Authors: Dolgikh V.A. , Rudoi I.G. , Soroka A.M.
Published: February 2023

The collisional lasers are attractive owing to the possibility of obtaining high energy and lasing power on excitation of large volumes of compressed gases. The ionizing pumping that is well-known since the middle 60-ies, the electron-beam pumping mainly, may be intended just for these conditions. At the same time, the efficient (>1% efficiency) short-wavelength (λ ≤ 1 μm; the excimer systems are not considered) collisional lasers with ionizing excitation appeared only after 1985 substantially by the efforts of our group, and the efficiency of near IR lasers due to d-p transitions of heavy inert gases did not exceed 1-3% [1].
Self-Consistent Coupled Cavity Treatment of Multimode Dynamics in Laser Diodes with Optical Feedback
Authors: Spencer P.S. , Rees P. , Pierce I. , Shore K.A.
Published: February 2023

Semiconductor lasers exposed to external optical feedback have been found to exhibit a wide variety of behaviour. In particular dramatic spectral broadening has been observed over a large range of feedback levels. This phenomenon, commonly referred to as Coherence Collapse, has been found to be a consequence of chaotic dynamics.
New Frequency Conversion Effects in HIO3 and α-LiIO3 Single Crystals Showing high χ(2) and χ(3) Nonlinear Susceptibilities
Authors: Kaminskii A.A. , Butashin A.V. , Hulliger J. , Egger P. , Mikhail P. , Eichler H.J. , Findeisen J. , Lyashenko A.I.
Published: February 2023

We report on first experimental observations of new manifestations of nonlinear optical interactions under one micron picosecond excitation in acentric HIO3 and α-LiIO3 single crystals, which offer simultaneously high χ(2) and χ(3) nonlinear effects.
Planar CO2-Laser With Hybrid Waveguide-Unstable Resonator Cavities
Authors: Mineev A.P. , Nefedov S.M. , Pashinin P.P.
Published: February 2023

The planar CO2 lasers with one-dimension hybrid unstable resonator, in which radiation propagates by both the waveguide and free-space way, are widely used for effective extraction of the storaged energy from a large area active medium [1,2]. The using of such a resonator provides the lowest transverse mode of the laser radiation with divergence close to diffraction-limited. Both the experimental study arid numerical modelling of various schemes of hybrid waveguide unstable resonators are important for the optimisation of the output power and spatial distribution of a laser beam.
Parametric Interactions in the Organic Salt 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate at telecommunication wavelengths
Authors: Meier U. , Bösch M. , Bosshard Ch. , Günter P.
Published: February 2023

Organic salts based on strong Coulomb interactions between charged molecules often show non-centrosymmetric packing as e.g. the 4-dimethylamino-N-methyl-stilbazolium salts. The material with the largest second-order nonlinearities in this class is 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST). DAST crystals are very interesting especially for electro-optic applications due to the exceptionally large nonlinear optical susceptibilities, the good alignment of the chromophores in the crystal and the large crystal size [1]. Due to the almost parallel alignment of the stilbazolium chromophores DAST was believed to be less suitable for phase-matched parametric interactions such as e.g. frequency-doubling.
Non-steady-state photocurrents and holographic recording in indium-oxide (In2O3) thin films
Authors: Sokolov I. A. , Kulikov V. V. , Mailis S. , Tzamali E. , Papademetriou Ch. , Ikiades A. , Kalpouzos C. , Vainos N. A.
Published: February 2023

Indium-oxide thin films present interesting electrical and optical properties and high potential for technological applications. The conductivity of indium-oxide thin films grown by dc-magnetron or laser sputtering can be modified upon illumination with ultraviolet radiation (photon energy >3.5 eV), resulting in a variable electrical state of the films from a resistive to a purely conductive one, while recently holographic recording has been demonstrated [1] aiming to information storage and processing applications.
Solid State Phase Conjugate Mirrors for ND-YAG Lasers: Recent Results with Photorefractive RH-Batio3 and Gain Media
Authors: Huignard J-P. , Brignon A. , Sillard P.
Published: February 2023

Phase conjugation based on four wave mixing (4WM) in nonlinear materials is of great interest for dynamic correction of intracavity phase aberrations in Nd-YAG lasers. For pulsc laser operation the phase conjugation is usually performed in bulky gas or liquid cells using stimulated Brillouin scattering. However, due to the progress of the laser technology it is now required to investigate new solid-state phase conjugate mirrors which exhibit high reflectivity and fidelity. For this purpose we will present and discuss two types of nonlinear mirrors - first, the IR sensitive Rb doped BaTiO, crystal, second the flash (or diode) pumped Nd-YAG (or Nd-YVO) gain media.
Spectroscopic characterization of Mn:YAlO3, material for holographic recording and optical data storage
Authors: Noginov M. A. , Loutts G. B. , Noginova N. , Warren M. , Jackson C. , Bonner C. , Rakhimov R. , Ries H.
Published: February 2023

In work [1] we have studied photoinduced absorption, associated with it refraction index change, and holographic grating recording in Mn doped yttrium orthoaluminate (Mn:YAlO3). We have shown Mn:YAlO3 to be a promising material for optical storage and holography. In the present work, we spectroscopically investigate Mn ions in different valence states as well as transitions between different valence states responsible for photoinduced coloration of Mn:YAlO3.
Determination of Second-Order Nonlinearities of Thin Films of Low Symmetry
Authors: Kauranen Martti , Van Elshocht Sven , Verbiest Thierry , Persoons André , Nuckolls Colin , Katz Thomas J.
Published: February 2023

Second-harmonic generation is a sensitive probe of surfaces and thin films. However, it is difficult to recognize structures of low symmetry. For example, distinction between anisotropy and chirality is nontrivial [1]. Azimuthal rotation of the sample about surface normal is sensitive to anisotropy. However, for focused beams, sample anisotropy and inhomogeneity can lead to similar rotation patterns. Here, we complement azimuthal rotation with polarization measurements (Fig. 1) to study thin films of low symmetry. Our technique does not rely on the absolute levels of different second-harmonic signals and is limited only by the accuracy of single polarization measurements.
Thermal imaging with pyroelectric vidicons
Authors: Ennulat R. D.
Published: February 2023

This paper reviews the major problems plaguing the pyroelectric vidicon from its inception: short tube life, low responsivity and spatial resolution, ineffective temporal modulation of the radiation. The tube life was extended from a few hundred to over two thousand operating hours by abandoning the gassy tube approach, in which negative charges are eliminated by positive ions1 and going to hard vacuum tubes. The latter required a new readout method to reset the target potential by secondary electron emission.2 Special coatings protect the targets against erosion by the electron beam and impose a responsivity that is uniform within about 5 %. The tube performance was increased by reducing the electron beam discharge lag. This was achieved by using a laminar flow electron gun to lower the beam impedance and by replacing the triglycine sulfate target by deuterated triglycine fluoroberyllate to reduce the capacitance.3 These measures improved the performance of the panning camera with a T/1 optics from a minimum detectable temperature difference of 0.5°C at 100 TV lines to 0.5°C at 250 TV lines. Temporal modulation of the input radiation, required to generate video signals in pyroelectric vidicons, restricts the camera operation either to imaging of moving objects or to panning or chopping. These modes will be discussed, and it will be shown that chopping and proper signal processing4 remove the thermal streaking characteristic of the panning mode without introducing objectionable flicker. As a result pyroelectric vidicon cameras approach the image quality of a well designed infrared scanner having the equivalent performance.
Fiber optic array splicing
Authors: Miller C. M.
Published: February 2023

A technique has been reported1 that shows promise for field-splicing groups of optical fibers. Grooved aluminum chips were initially interleaved between linear arrays of optical fibers to form a precise two-dimensional array. This array was then potted to retain the precise geometry and polished to provide good ends on all the fibers at once. Two such arrays are brought together to form a butt joint splice. Improved chips are presently being used that yield greatly improved alignment. This alignment improvement promises a significant reduction over the array splice loss that was obtained with the original aluminum chips1 (mean loss = 0.42 dB with 70% less than 0.5 dB).
Sensory representation of surface reflectances: assessments with hyperspectral images
Authors: Karimipour Hamed , O’Regan J. Kevin , Witzel Christoph
Published: February 2023

Specifying surface reflectances in a simple and perceptually informative way would be beneficial for many areas of research and application. We assessed whether a 3×3 matrix may be used to approximate how a surface reflectance modulates the sensory color signal across illuminants. We tested whether observers could discriminate between the model’s approximate and accurate spectral renderings of hyperspectral images under narrowband and naturalistic, broadband illuminants for eight hue directions. Discriminating the approximate from the spectral rendering was possible with narrowband, but almost never with broadband illuminants. These results suggest that our model specifies the sensory information of reflectances across naturalistic illuminants with high fidelity, and with lower computational cost than spectral rendering.
Qualitative assessment of family caregiver-centered neonatal education program in Karnataka, India
Authors: Yan Shirley D. , S.D. Sahana , Desai Meghna , Delaney Megan Marx , Bobanski Lauren , Rajkumar N. , Murthy Seema , Henrich Natalie
Published: February 2023

Globally 2.5 million newborns die every year before they reach the age of one month; the majority of these deaths occur in low- and middle-income countries. Among other factors, inadequate knowledge and skills to take care of newborns contribute to these deaths. To fill this gap, training patients and family members on the behaviors needed to improve essential newborn care practices at home is a promising opportunity. One program that aims to do this is the Care Companion Program (CCP) which provides in-hospital, skills-based training on care of mothers and newborns to families. This study uses semi-structured interviews to understand how and why knowledge and behaviors of maternal and newborn care behaviors change (or don’t change) as a result of CCP sessions and participants’ perception of the impact of CCP on change. Interviews focused on knowledge and behaviors around key neonatal and newborn topics and health seeking behaviors for health complications. Forty-two in-depth interviews were conducted among families with recently-delivered babies at their homes from four districts in Karnataka, India. Respondents have a positive perception about CCP, found training useful and appreciated other family members presence during the training. CCP increased knowledge and awareness and provided critical details to key behaviors like breastfeeding. Respondents were more likely to be receptive toward details on already known topics, like hand washing before touching the baby. Awareness increased on newly learned behaviors, like skin-to-skin care, which don’t conflict with cultural norms. The CCP did not influence nonrestrictive maternal diet as much, which cultural norms heavily influence. In-hospital family caregiver education programs, like CCP, can positively influence key neonatal behaviors by imparting knowledge and key skills. However, the effect is not universal across health behaviors.
Community-orientated primary health care: Exploring the interface between community health worker programmes, the health system and communities in South Africa
Authors: Malatji Hlologelo , Griffiths Frances , Goudge Jane
Published: February 2023

Due to insufficient number of health workers and the evidence of the benefits of community health workers (CHWs), CHWs are being deployed to provide health care services to under-served communities. In this article, we explore to what extent the South African CHW programmes introduced between 2009 and 2011 are attuned to community needs, integrated into the healthcare system and community structures, and also implemented in accordance with community-orientated primary health care principles. Using a case study approach, we studied CHW teams in seven primary healthcare facilities located in semi-urban and rural areas of Gauteng and Mpumalanga provinces, South Africa. We collected data using in-depth interviews involving facility managers, CHW supervisors, community representatives and key informants, and focus groups and observations of CHWs. The implementation of community-orientated health interventions remains complex. In the different sites, there were efforts to integrate the views of stakeholders (e.g., political leaders) into the implementation of the CHW programmes. However, many residents were more concerned about access to housing than health services. The CHWs services’ were found to be generally comprehensive, however inefficient training, supervision and mentorship limited their effectiveness. The multidisciplinary approach to care, as introduced by some sites, helped enhance the knowledge and skills of some of the CHWs on complex health topics. The roll out of community orientated primary health care services is crucial in a resource-constrained setting like South Africa. However, significant socio-economic issues disrupt community involvement and the effective provision of services. Governments need to provide sufficient funds for training, supervision, supplies and remuneration to help overcome these barriers.
High-resolution spatiotemporal changes in dominant frequency and structural organization during persistent atrial fibrillation
Authors: Pong Terrence , Aparicio-Valenzuela Joy , Obafemi Oluwatomisin , Cyr Kevin , Carlton Cody , Taylor Calvin , Lee Anson
Published: February 2023

Objective

Analyze changes in frequency activity and structural organization that occur over time with persistent atrial fibrillation (AF)

Background

Little is known about the frequency characteristics of the epicardium during transition from paroxysmal to persistent AF. Accurate identification of areas of high dominant frequency (DF) is often hampered by limited spatial resolution. Improvements in electrode arrays provide high spatiotemporal resolution, allowing for characterization of the changes that occur during this transition.

Methods

AF was induced in adult Yorkshire swine by atrial tachypacing. DF mapping was performed using personalized mapping arrays. Histological analysis and late gadolinium enhanced magnetic resonance imaging were performed to determine structural differences in fibrosis.

Results

The left atrial epicardium was associated with a significant increase in DF in persistent AF (6.5 ± 0.2 vs. 7.4 ± 0.5 Hz, P = 0.03). The organization index (OI) significantly decreased during persistent AF in both the left atria (0.3 ± 0.03 vs. 0.2 ± 0.03, P = 0.01) and right atria (0.33 ± 0.04 vs. 0.23 ± 0.02, P = 0.02). MRI analysis demonstrated increased ECV values in persistent AF (0.19 vs 0.34, paroxysmal vs persistent, P = 0.05). Tissue sections from the atria showed increase in fibrosis in pigs with persistent AF compared to paroxysmal AF. Staining demonstrated decreased myocardial fiber alignment and loss of anisotropy in persistent AF tissue.

Conclusions

Changes in tissue organization and fibrosis are observed in the porcine model of persistent AF. Alterations in frequency activity and organization index can be captured with high resolution using flexible electrode arrays.
The prevalence of metabolic conditions before and during the COVID-19 pandemic and its association with health and sociodemographic factors
Authors: Mamudu Hadii M. , Adzrago David , Odame Emmanuel O. , Dada Oluwabunmi , Nriagu Valentine , Paul Trishita , Weierbach Florence W. , Dowling-McClay Karilynn , Stewart David W. , Adams Jessica , Paul Timir K.
Published: February 2023

Background

There is a dearth of evidence on the relationship between COVID-19 and metabolic conditions among the general U.S. population. We examined the prevalence and association of metabolic conditions with health and sociodemographic factors before and during the COVID-19 pandemic.

Methods

Data were drawn from the 2019 (N = 5,359) and 2020 (N = 3,830) Health Information National Trends Surveys on adults to compare observations before (2019) and during (2020) the COVID-19 pandemic. We conducted weighted descriptive and multivariable logistic regression analyses to assess the study objective.

Results

During the pandemic, compared to pre-pandemic, the prevalence of diabetes (18.10% vs. 17.28%) has increased, while the prevalence of hypertension (36.38% vs. 36.36%) and obesity (34.68% vs. 34.18%) has remained similar. In general, the prevalence of metabolic conditions was higher during the pandemic (56.09%) compared to pre-pandemic (54.96%). Compared to never smokers, former smokers had higher odds of metabolic conditions (AOR = 1.38, 95% CI = 1.01, 1.87 and AOR = 1.57, 95% CI = 1.10, 2.25) before and during the pandemic, respectively. People with mild anxiety/depression symptoms (before: AOR = 1.52, 95% CI = 1.06, 2.19 and during: AOR = 1.55, 95% CI = 1.01, 2.38) had higher odds of metabolic conditions relative to those with no anxiety/depression symptoms.

Conclusion

This study found increased odds of metabolic conditions among certain subgroups of US adults during the pandemic. We recommend further studies and proper allocation of public health resources to address these conditions.
Divergence time of mites of the family Laelapidae based on mitochondrial barcoding region
Authors: Yang Huijuan , Chen Ting , Dong Wenge
Published: February 2023

Using the mitochondrial barcoding region to correlate research with 58 species in 19 genera of the family Laelapidae with the aim of determining the origin, phylogenetic relationships, and biogeographic historical distribution characteristics of mites in the family Laelapidae. Phylogenetic trees were obtained using Bayesian inference (BI) and Maximum-likelihood (ML) methods, based on three fossil records calibrated as molecular clock nodes, to estimate the divergence time of mites in the family Laelapidae as well as to apply Dispersal-Extinction-Cladogenesis (DEC) analyses to obtain biogeographic history inferences. The result showed species of the genera Hyperlaelaps and Haemolaelaps and some species of the genus Androlaelaps in the family Laelapidae were divided into clades of the genus Laelaps in both the BI and ML trees. Divergence time estimates and biogeographic history analysis revealed that the family Laelapidae likely diverged from other taxa during the Middle Jurassic (ca. 156.73 Mya), with Asia considered the most likely ancestral region for the family Laelapidae. Species of various genera began to undergo massive diversification events during the Cenozoic Tertiary. The results suggest that some genera in the family Laelapidae need to be re-defined or new genera need to be established; the Late Cretaceous to Late Neogene warm period would have promoted the divergence and expansion of species in the family Laelapidae. The divergence and dispersal of the family Laelapidae species is most likely a joint response to the continued northward drift of the Indian plate away from the Gondwana paleo-continent and gradually closer to Asia during the Late Cretaceous and the geological activity of the Tibetan Plateau during the Cenozoic Tertiary. The results strengthen our understanding of the origin and evolution of species in the family Laelapidae.
The experience of leaving a valuable object: An investigation of emotional processes related to Hoarding disorder features
Authors: Pardini Susanna , Olivetto Silvia , Fusina Francesca , Novara Caterina
Published: February 2023

One of the core features of hoarding is a significant resistance to discarding objects, which is fueled by dysfunctional beliefs and unwarranted negative emotions that hoarders tend to feel when disposing of their possessions. To our knowledge, longitudinal studies investigating the psychological effects that people who hoard experience after separating from their valuable possessions have yet to be conducted. Our study’s principal aim was to explore psychological processes that individuals with high hoarding features (n = 53; 49.1%) and individuals with low hoarding features (n = 55; 50.9%) experienced when they had to separate from a valuable possession. To do this, we evaluated participants’ thoughts and feelings at several time points after they had to leave a valuable object at the University laboratory (evaluations were specifically conducted at baseline, during the week, and at the end of the week). To investigate hoarding and anxiety, as well as depressive, obsessive-compulsive, and emotional processes-related features, a mixed-method approach was employed involving self-report questionnaires, ad hoc surveys, and a daily self-monitoring schedule. Our findings showed that compared to participants with low hoarding features, participants with high hoarding traits: 1) scored higher for anxiety sensitivity, distress tolerance, and emotional dysregulation; 2) reported having more negative emotions when leaving their object; 3) had more intrusive object-related beliefs; and 4) experienced a higher frequency of negative emotions as well as a higher level of distress during the week. Both groups experienced more negative emotions in the first part of the week, which decreased as the time at which participants could receive their object back drew closer. Finally, dysfunctional beliefs about leaving a personal object (Saving Cognitions Inventory), sensitivity to anxiety (Anxiety Sensitivity Index-3), and distress tolerance (Distress Tolerance Scale) contributed to the level of discomfort that participants with higher hoarding scores reported when they had to leave their possession. These results highlight the relevance of emotional processes in the hoarding disorder framework as well as underscore the importance of assessing and treating them in clinical settings.
Patients with abdominal aortic aneurysms have reduced levels of microRNA 122-5p in circulating exosomes
Authors: Lopez Jose L. , Ramirez Joel L. , Phu Tuan Anh , Duong Phat , Bouchareychas Laura , Kuhrau Christina R. , Lin Pei-Yu , Eckalbar Walter L. , Barczak Andrea J. , Rudolph Joshua D. , Maliskova Lenka , Conte Michael S. , Vartanian Shant M. , Raffai Robert L. , Oskowitz Adam Z.
Published: February 2023

Objective

There are currently no specific biomarkers to identify patients with abdominal aortic aneurysms (AAAs). Circulating exosomes contain microRNAs (miRNA) that are potential biomarkers for the presence of disease. This study aimed to characterize the exosomal miRNA expression profile of patients with AAAs in order to identify novel biomarkers of disease.

Methods

Patients undergoing duplex ultrasound (US) or computed tomography (CT) for screening or surveillance of an AAA were screened to participate in the study. Cases with AAA were defined as having a max aortic diameter >3 cm. Circulating plasma exosomes were isolated using Cushioned-Density Gradient Ultracentrifugation and total RNA was extracted. Next Generation Sequencing was performed on the Illumina HiSeq4000 SE50. Differential miRNA expression analysis was performed using DESeq2 software with a Benjamini-Hochberg correction. MicroRNA expression profiles were validated by Quantitative Real-Time PCR.

Results

A total of 109 patients were screened to participate in the study. Eleven patients with AAA and 15 non-aneurysmal controls met study criteria and were enrolled. Ultrasound measured aortic diameter was significantly larger in the AAA group (mean maximum diameter 4.3 vs 2.0 cm, P = 6.45x10-6). More AAA patients had coronary artery disease (5/11 vs 1/15, P = 0.05) as compared to controls, but the groups did not differ significantly in the rates of peripheral arterial disease and chronic obstructive pulmonary disease. A total of 40 miRNAs were differentially expressed (P<0.05). Of these, 18 miRNAs were downregulated and 22 were upregulated in the AAA group compared to controls. After false discovery rate (FDR) adjustment, only miR-122-5p was expressed at significantly different levels in the AAA group compared to controls (fold change = 5.03 controls vs AAA; raw P = 1.8x10-5; FDR P = 0.02).

Conclusion

Plasma exosomes from AAA patients have significantly reduced levels of miRNA-122-5p compared to controls. This is a novel exosome-associated miRNA that warrants further investigation to determine its use as a diagnostic biomarker and potential implications in AAA pathogenesis.
Mental health, cancer risk, and the mediating role of lifestyle factors in the CARTaGENE cohort study
Authors: Gilham Kaitlyn , Gadermann Anne , Dummer Trevor , Murphy Rachel A.
Published: February 2023

Background

Evidence on the association between mental health disorders and cancer risk is inconclusive, despite well-established associations between mental health disorders and lifestyle factors such as smoking. This study examines the relationships between depression, anxiety and cancer risk, and the potential mediating effects of lifestyle factors.

Methods

A study of 34,571 participants aged 40–69 years in the CARTaGENE cohort was conducted. Depression was defined by questionnaire (PHQ-9), antidepressant use, and a composite of questionnaire, antidepressant use, or lifetime self-reported physician diagnosis. Anxiety was defined by questionnaire (GAD-7). Co-morbid depression and anxiety was also assessed. Cox regression models were used to investigate associations between mental health and risk of prostate, lung, and all cancers combined. Mediating effects of lifestyle factors were assessed using Baron and Kenny mediation criteria.

Results

There were positive associations between mental health disorders, all cancers and lung cancer risk, however with the exception of anxiety and lung cancer in women (Hazard Ratio [HR] = 1.67, 95% CI: 1.01–2.76), associations were attenuated with adjustment for sociodemographics, health status and lifestyle factors. In the mediation analysis, smoking accounted for 27%, 18%, and 26%, of the total effect between depression (PHQ-9), anxiety, and co-morbidity and lung cancer, respectively in women. In men, smoking accounted for 17% of the total effect between depression (PHQ-9, antidepressant, or lifetime self-report of physician diagnosis) and all cancers.

Conclusions

Positive associations were observed between mental health disorders, all cancer and lung cancer risk, however most relationships were attenuated with adjustment for lifestyle factors. Smoking status mediated a significant proportion of the relationships between mental health disorders and cancer risk.
Az alapképességek fejlődése
Authors: Molnár Gyöngyvér
Published: February 2023

Nagy József szerepe a hazai empirikus neveléstudományi kutatások
folyamatos módszertani megújításában megkérdőjelezhetetlen. A tanulmányban
áttekintjük azokat a kutatási irányzatokat, amelyek jelentősen
meghatározták a hazai képességvizsgálatok módszertanát, illetve
összefoglaljuk a képességek rendszerezésére, mérésére, fejlődési
folyamataik feltárására fókuszáló, a ’60-as évek óta, Nagy József
irányítása alatt folyt vizsgálatok módszertani változását, felvillantva a
mai vonatkozó fejlesztéseket. A képességvizsgálatok között – többek között
a tanulási sikerességet meghatározó szerepük miatt – kulcsfontosságú
szerepet játszottak és játszanak a kognitív képességekre vonatkozó, a
gondolkodás, megismerés, tudás alkalmazását segítő képességek vizsgálata és
fejlesztése. A kutatási eredmények alapján megállapítható, hogy minden
készség, képesség fejlődése, legyen akár gondolkodás képességről szó, több
évet, akár 5-10 évet is igénybe vesz, és a fejlesztés szempontjából
szenzitív szakasz az iskolai évekre esik. Ezen időszakban szükséges lenne
iskolai direkt fejlesztésük.
Önszabályozás a tanulásban
Authors: D. Molnár Éva
Published: February 2023

A tanulmány célja az önszabályozott tanulás meghatározásával,
modellálásával és empirikus vizsgálatával kapcsolatos kutatások elméleti
összegzése és a fontosabb tendenciák bemutatása. Felvázolja az
önszabályozott tanulás kutatásában történt változások irányát, valamint az
önszabályozott tanulás iskolai eredményességben betöltött szerepét. A
tanulmány külön kitér Nagy József önszabályozás-értelmezésére és
személyiségfejlődési modelljének nemzetközi összehasonlítására, végül
bemutatja az önszabályozás tanulásban és az egész személyiség fejlődésében
betöltött kulcsszerepét.