bluuebunny/crossref_metadata_2025 huggingface dataset:
Are There Two-Level Systems in Crystals? Anomalous Temperature Broadening of Zero-Phonon Line of Perylene in N-Octane
Authors: Korotaev O. N. , Kolmakov I. P. , Karpov V. P. , Shchanov M. F.
Published: February 2023

Recent experimental data show that the optical dephasing processes leading to zero-phonon lines (ZPL) temperature broadening in the spectra of impurity crystals result from quadratic electron-phonon interaction [1-4]. However, this theory fails to describe some of the experimental results [4]. We suppose that another mechanism of ZPL temperature broadening in crystal can exist. The experimental data presented in this paper show that the temperature broadening of ZPL is due to the low-frequency excitation of non-phonon type. They are excitations in so-called Two-Level Systems (TLS) [5,6], which are under discussion at present with respect to dephasing processes in polymers and glasses [2].
Persistent Spectral Hole-Burning by cw lasers in Defect-Aggregates Induced by Particle Irradiation
Authors: Bauer R. , Attenberger T. , Sildos I. , Bogner U. , Maier Max
Published: February 2023

In different color centers of neutron- irradiated and annealed sapphire crystals persistent spectral holes could be burned which were thermoresistant up to 670K [1]. In the 755.6nm zero-phonon line (ZPL) two-color photon-gated persistent spectral hole-burning (PSHB) was obtained with pulsed dye-lasers [2]. Preliminary results of PSHB with a cw laser were reported for the 462.5nm ZPL [3]. The present study concerns a investigation of PSHB with cw-lasers in different ZPL, including the 755.6nm ZPL, which is interesting for potential applications in particular because diode lasers are available in this spectral range.
Spatial Resolution of Spectral Hole-Burning-Based Information Storage
Authors: Rebane I. , Kikas J.
Published: February 2023

In the proposed 4D (3 spatial an 1 frequency dimension) optical memories two-or three-step spectral hole burning (SHB) by two or three light beams is used [1]. In 3D (2 spatial and 1 frequency dimension) optical memories a non-erasing readout is realized by two- step (photon-gated (PG)) SHB. Here we consider the effects of PG SHB on the spatial storage density in 3D and 4D optical memories.
High-Speed Pattern Recognition: An Application of Time-Domain Optical Memories
Authors: Shen X. A. , Kachru R.
Published: February 2023

The demonstrated dual ability of a time-domain optical memory (TDOM) to store and process two-dimensional images1-4 makes it an ideal candidate for high-speed pattern recognition. We present here experimental results demonstrating its potential for such applications.
Influence of dephasing processes and temperature effects on transient hole-burning
Authors: Villaeys A.A. , Vallet J.C.
Published: February 2023

There has been a very rapid development in the experimental and theoretical treatments of ultrafast processes. Among all the spectroscopic techniques which enable us to understand the dynamics, as well as the mechanisms taking place between a molecule and its surrounding, transient hole-burning [1] holds the prospect of differentiating the homogeneous component resulting from very rapid interactions from the inhomogeneous conponent generated by the slowly varying interactions. Recently some limitations to transient hole-burning in the liquid phase have been identified [2]. For a narrow pump pulse, and a time delay short enough to avoid the influence of the spectral diffusion, the homogeneous linewidth is proportional to the hole width. If the spectral diffusion is rapid, the homogeneous contribution is then unobservable. Moreover, spectral congestion generates an overlaping of the holes corresponding to the vibrational structure. Also, Lauberau et al. [3] have developed and reported the application of picosecond time-resolved hole-burning to study the dynamics of inhomogeneous molecular systems in the infrared frequency domain. In their experiment, the pump and probe pulse overlap. Although previous description have taken into account the artifact contribution which comes from the overlap of the pulses, in the present work we shall give a theoretical description of ultrafast transient hole-burning to emphasize the effects of pure dephasing processes as well as temperature effects.
Room-Temperature Persistent Spectral Hole-Burning in Sm2+-Doped Glass
Authors: Kurita A. , Kushida T. , Izumitani T. , Matsukawa M.
Published: February 2023

We report the first observation of room-temperature persistent spectral hole-burning in glass. The holes were burned in the 7F0→5D0 line of Sm2+ ions in fluorohafnate glass.
Dynamics and Guest-host Interactions of Chromophores in Inorganic Cage Structures
Authors: Deeg F.W. , Ehrl M. , Bräuchle C.
Published: February 2023

Recent progress in chemical synthesis techniques has made it possible to prepare specifically tailored well-defined inorganic cage and channel structures on an Å-scale, so-called molecular sieves, with encapsulated chromophores [1]. The best-known of these inorganic crystals are zeolites which possess an aluminosilicate framework but many more classes of molecular sieves like e.g. metalloaluminates or aluminophosphates are available. The structural and dynamical properties of chromophores encaged in these porous solids are modified by the spatial restrictions enforced by the environment, see e.g. [2]. In this contribution we report about the application of the sensitive techniques of fluorescence line narrowing and spectral hole-burning to probe chromophore dynamics and interactions of the adsorbate with the lattice in these confined geometries.
Persistent Spectral Hole-Burning of Dye Molecules Adsorbed on Heterogeneous Surfaces
Authors: Bräuchle C. , Sauter B. , Kettner R.
Published: February 2023

In this talk we review our recent results on dye-surface systems investigated by persistent spectral hole-burning. Dye-surface systems are an interesting class of hole-burning materials. In most dye-surface systems investigated by us stable holes can be burnt and detected at unusual high temperatures [1,2,3]. In addition, the understanding of the interaction between adsorbed molecules and the heterogeneous surface may provide new insights in processes important in catalysis.
Optical Hole-Burning Spectroscopy of Methyl Group Tunneling and the Temperature Dependence of the Nuclear Spin Conversion Rate
Authors: Joyeux M. , Prass B. , Trommsdorff H.P. , Vial J.C. , von Borczyskowski C.
Published: February 2023

A newly developed optical hole-burning technique gives direct access to the nuclear spin conversion rate between the methyl group tunneling levels in the solid state and allows a comparison between the tunneling splitting in different electronic states. Using low temperature techniques spin conversion in dimethyl-s-tetrazine doped single crystals of durene could be followed for over more than 106 s. The relaxation data show below 4 K a transition from an Orbach to a Raman type temperature law as has been predicted by theory.
Inorganic and Hybrid (organic-inorganic) Sol-Gel Glasses doped with Organic Molecules: Fluorescence Line Narrowing, Persistent Hole-Burning and Spectral Diffusion
Authors: Galaup J.P. , Veret-Lemarinier A.V. , Kulikov S. , Arabei S. , Boilot J.P. , Chaput F.
Published: February 2023

We used spectral line narrowing techniques (site selection spectroscopy and persistent spectral hole-burning) to investigate the vibronic visible spectra of different porphyrins included in various sol-gel matrices. Also, quinizarin and a quinizarin derivative have been studied. The main aim of this work is to compare pure inorganic matrices and hybrid (organic-inorganic) matrices in which organic groups are permanently attached to the inorganic squeleton.
Spectral Hole Burning: Data Storage and Processing
Authors: Wild Urs P. , Maniloff Eric S. , Bernet Stefan , Renn Alois
Published: February 2023

At very low temperatures, the spread in the different environments of matrix embedded dye molecules results in an inhomogeneously broadened S1 ← S0 band. Spectroscopic techniques based on the appearence of optical zero phonon lines, such as fluorescence line narrowing, spectral hole-burning, and single molecule spectroscopy provide an experimental resolution limited by the homogeneous linewidth. From the investigation of the homogeneous line width as a function of different parameters (time, temperature) information on the guest host interactions responsible for the observed linewidth is obtained. Spectrally narrow features are extremely sensitive probes for external perturbations, such as electric fields, magnetic fields, or hydrostatic pressure.
Optical Addressing and Switching of Water Molecules in Hole Burning Systems: A TLS Model System
Authors: Barth K. , Richter W.
Published: February 2023

The change in the profile of a spectral hole can be used to detect tunneling processes in glassy matrices as well as light-induced changes of molecular configurations. The broadening of photochemical holes as well as hole-filling processes are very sensitive probes for molecular rearrangements arround the embedded dye molecules /1/. Light-induced spectral diffusion in polymeric systems is highly selective with respect to the optical excitation of vibrational modes of the surrounding molecular groups.
Temperature-Annealing-Cycling Hole Burning Spectroscopies of Dye and Dye-Oligonucleotide Doped in Polymer Films
Authors: Chang Ta-Chau , Chiang Chien-Chih , Chou Shiow-Hwa
Published: February 2023

We have measured the temperature-annealing-cycling hole spectra of 5-(and 6-) carboxy-X-rhodamine N-hydroxy succinimidyl ester (RhSE) and the RhSE molecule with binding to the oligonucleotide of ten bases of Guanine (RhSE-10G) doped in polyvinyl alcohol (PVOH) films, respectively. Figure 1 shows the temperature-annealing-cycling hole spectra of zero phonon hole (ZPH) of RhSE/PVOH and RhSE-10G/PVOH, which were taken after burning 5 and 10 mins with a flux of ~ 40 mW/cm2 at λB ~ 5812 Å, respectively. It is found that the holes are reduced by 40 % and 50 % in the annealing spectra at Ta ~ 18 K. However, part of the holes are recovered when the systems are cycled back to the burning temperature at Tc = 6 K. It is found that the hole reduction in the annealing spectrum of RhSE-10G/PVOH is more dominant than that of RhSE/PVOH.
Linewidths In Spectra Of Terrylene In Polyethylene Probed By Incoherent Photon Echo. Comparison With Single Molecule Spectroscopy Data
Authors: Gruzdev N.V. , Personov R.I. , Vainer Yu.G.
Published: February 2023

The concept of the homogeneous spectral linewidth of an impurity center is more complicated in disordered media such as organic glasses and polymers than it is in crystals. In amorphous media the local environments for impurity centers are continuously changing with time. As a result transition frequencies of individual centers diffuse within the inhomogeneous broadened spectral contour, which is called spectral diffusion. When the timescale for spectral diffusion processes is much longer than the dephasing time, it is possible to distinguish homogeneous dephasing from spectral diffusion. On the other hand, when the timescales of spectral diffusion and dephasing processes are comparable these phenomena become indistinguishable.
Multi-Wavelength Recording at Room-Temperature by Gated Persistent Spectral Hole-Burning in SrFCl0.5Br0.5:Sm2+
Authors: Umezu Nobuhiko , Asatsuma Tsunenori , Takemoto Yoshihiro , Kaneko Masahiko
Published: February 2023

Persistent spectral hole-burning has been proposed as a frequency domain data storage method that allows us to make ultra-high density optical recordings compared with conventional optical disks. Most reports have been on organic materials at relatively low temperatures so far. Recently, intense interest has been shown in the room temperature operation of inorganic materials, which have some structural inhomogeneity introduced to crystal structure [1], and specific glasses [2,3]. We have investigated the characteristics of SrFCl0.5Br0.5:Sm powder samples for higher density optical recording materials. We have reported the photon-gated recording and reading characteristics of this materials at room temperature in a relatively broad 1mm diameter area which was irradiated by a laser beam of several mW [4]. However it is necessary to record and read holes onto a much smaller area for optical disk applications. There have been very few reports on this topics. We have investigated room-temperature gated hole recording, reading, erasing, and multiple data-recording with pm order focused beam and several mW of laser power.
Optical Spectroscopy of Single Pentacene Molecules in Disordered p-Terphenyl Crystals
Authors: Rummer S. , Basché Th. , Bräuchle C.
Published: February 2023

Fluorescence excitation spectroscopy of single dye molecules in crystals offers the possibility to determine molecular paramaters of single absorbers and their distribution instead of ensemble averages [1,2]. Informations about single molecules can be derived from the optical absorption spectra and from the time distribution of the fluorescence photons. The inhomogeneous broadening of an electronic transition reflects the variety of local environments accessible to the guest molecules and is therefore a measure for the degree of disorder or the defect concentration in the host crystal [3,4]. For pentacene molecules in p-terphenyl crystals (c ≈ 10−8mole/mole) we observed different types of inhomogeneous broadening: Some crystals show a narrow (FWHM ≈ 1 GHz) Lorentzian line with a satellite structure at short wavelengths due to 13C substitutional isomers of pentacene. The inhomogeneous line of other crystals is remarkable broadened and neither Lorentzian nor Gaussian. The intersystem crossing (ISC) rates k23 and k31 can be determined by measuring the intensity autocorrelation function of the fluorescence light [5]. In a crystal with low degree of disorder (narrow Lorentzian inhomogeneous broadening) the ISC rates of the molecules show a smaller distribution than in a crystal with higher degree of disorder (broadened line). The fully saturated fluorescence emission rates as calculated using the ISC rates are consistent with the experimentally measured photocount rates.
Spectral Hole-Burning at Room Temperature in a Thin Film of SrFClxBr(1-x):Sm2+
Authors: Asatsuma Tsunenori , Umezu Nobuhiko , Takemoto Yoshihiro , Kaneko Masahiko
Published: February 2023

One of the most attractive features of spectral hole-burning (SHB) is the possible its application to higher-density data storage media(1,2). Since the recent successes of SHB at room temperature in Sm2+-doped materials(3-6), the possibility of their practical use has become much larger. In that sense, inorganic materials containing Sm2+ are of interest to us(7).
Photochemical hole-burning: its non-site-selective aspects and applicability to optical memory
Authors: Murase Norio , Horie Kazuyuki
Published: February 2023

Since the discovery of photochemical hole-burning(PHB),1,2) this phenomenon is sometimes called site-selective spectroscopy. This site-selective feature has been proposed for wavelength domain recording to achieve ultra-high recording density.3)
Dependence Of The Fluorescence Of A Single Impurity Molecule On Light Polarization In Birefringent Crystals (Pentacene In P-Terphenyl)
Authors: Rebane I.
Published: February 2023

The most popular system for single molecule spectroscopy up to now is pentacene molecules introduced into p-terphenyl single crystal. P-terphenyl is a birefringent crystal and here arises a problem about the state of light polarization at the site of pentacene: the fluorescence intensity depends on the angle between the polarization and transition dipole moment of the molecule. This circumstance has found application in the measurement of the distance of the molecule from the crystal entrance surface [1]. In Ref.[1] formulae for finding the distance and the orientation of the dipole moment have been given and the respective values have been calculated. The aim of this paper is to derive more accurately formulae for these values, taking into account more precisely the properties of the electric field of the wave propagating in a birefringent crystal.
Spectral Holeburning in Tetraphenylporphyrin Doped Polymethylcellulose
Authors: Dou Kai , Zhang Jisen , Tian Mingzhen , Zhang Jiahua , Jin Chunming , Zhao Jialong , Huang Shihua , Yu Jiaqi
Published: February 2023

In our previous works, some holeburning results in organic materials with charge transfer were given. We achieved the photon-gated holeburning in a system containing the electron acceptor (p-hydroxybenzaldhyde (PHBA)) and the electron donor (Zn-tetraphenylbenzoporphyrin (Zn-TPBP) doped in a matrix (poly-methylmethacrylate (PMMA) ) [1-3]. In this paper, we will report the single photon holeburning at 25K in p- tetraphenylporphyrin (TPP) embedded in the matrix of polymethylcellulose. The mechanisms of holeburning and holefilling are discussed.
Wavelength and polarization dependence of hole-burning properties in highly oriented J-aggregates
Authors: Misawa Kazuhiko , Kobayashi Takayoshi , Machida Shinjiro , Horie Kazuyuki
Published: February 2023

J-aggregates of cyanine dyes show a sharp absorption peak, called J- band, below the transition band of monomers [1,2]. The band is due to the transition of excitons delocalized over an aggregate by intermolecular dipole interaction. A simple model of N identical molecules aligned in a one- dimensional chain has been proposed to explain the optical spectrum of the J- aggregates [3-5]. Recently, we have developed a new method, named "vertical spin-coating", to prepare highly oriented J-aggregates dispersed in polymer films [6]. Linear dichroic spectra, and electro-absorption spectra have been measured to study the optical properties of one-dimensional excitons in J- aggregates [7,8].
Photochemical Hole Burning of Organic Dye Doped in Inorganic Semiconductor: Zinc Porphyrin in Titanium Dioxide
Authors: Machida Shinjiro , Horie Kazuyuki , Yamasita Takashi
Published: February 2023

One of the topics of photochemical hole burning (PHB) materials is high-temperature PHB. This is not only important for optical applications but also important for purely scientific studies because high-temperature materials expand the temperature range in which we can obtain informations about electron-phonon interactions, structural relaxations, and photoinduced processes of guest-host systems. Although some of inorganic PHB materials show an excellent property that a hole can be burnt even at room temperature, holes of only few organic chromophores are observed above 80 K [1]. PHB systems with inorganic matrices have a possibility of showing high-temperature PHB for organic dyes. Organic dyes adsorbed on the surface of γ-almina are reported to show high-temperature hole formation and small temperature dependence of Debye-Waller factor (DWF) [2].
Femtosecond Photon Echo In Solids: Selective Spectroscopy Not Using Zero-Phonon Lines
Authors: Osad’ko I.S. , Stashek M.V.
Published: February 2023

Fluorescence—line—narrowing, spectral hole—burning and single molecule spectroscopy are methods of selective spectroscopy using zero-phonon lines (ZPL) to make selection in molecular ensemble. However if electron-phonon coupling is strong or sample temperature is near to room temperature, ZPL are absent and the optical band consists of electron-phonon transitions which are called phonon-side-band (PSB). In these cases the above mentioned methods of selective spectroscopy do not work. Can we get an information concerning a homogeneous optical band from inhomogeneously broadened bands in these cases? The answer is yes if we use femtosecond photon echo.
Persistent spectral hole-burning in CuBr nanocrystals
Authors: Kawazoe Tadashi , Yamamoto Tetsuya , Zimin Lev G. , Masumoto Yasuaki
Published: February 2023

Persistent hole-burning phenomena in ion-doped glass and organic-molecule-doped organic glass have been well known. In recent years semiconductor nanocrystals have been studied extensively because of their novel optical properties such as large optical nonlinearities, and their possibility for applications, such as lasers, ultrafast optical devices, and so on. However, so far "persistent spectral hole-burning (PSHB)" phenomenon in semiconductor nanocrystals has never been reported until the PSHB phenomenon was observed in CdSe and CuCl nanocrystals in our laboratory. Therefore, we may be able to find the other semiconductor nanocrystals which show persistent hole-burning phenomenon. In this publication, we report the persistent hole-burning phenomenon in CuBr semiconductor nanocrystals embedded in glass. Our experiment shows the spectral hole in CuBr nanocrystals remains for more than 8 hours without any detectable relaxation.
Ultrafast population transfer in ground states: evidence for two ground states of crystal violet
Authors: Maruyama Yoshihiro , Ishikawa Mitsuru
Published: February 2023

The presence of ground state conformers of crystal violet (CV) have been in dispute since 1942 when proposed by Lewis, Magel, and Lipkin.1 They suggested the two conformers in alcohols to explain the disappearance of a shoulder (~550 nm) and the enhancement of a peak (~590 nm) in the absorption spectrum at low temperature (114 K). The predominant conformer, which was assigned to the origin of the peak, was assumed D3 symmetry (propeller type) in which all phenyl groups are tilted in phase. The second conformer was supposed to have C2 symmetry (distorted propeller type), being sited as the origin of the shoulder, in which one of the phenyl groups is tilted in the opposite direction.
The role of divalent ions in persistent hole-burning mechanism in Y2O3:Pr3+ crystals
Authors: Okuno Tsuyoshi , Tanaka Koichiro , Suemoto Tohru
Published: February 2023

Persistent spectral hole-burning is extensively studied in many materials. In inorganic materials doped with rare earth ions, we have mainly two mechanisms for hole-burning; one is optical pumping to hyperfine sublevels in rare earth ions, and the other is optically induced rearrangement of local structure around optical centers. In crystals we often observe the hole due to the former mechanism while the hole due to the latter is reported mainly in glasses. Up to now, there seems to be only little study about the correlation between the mechanism of hole-burning and sample-quality or defects. Recently we reported that the character of holes in Y2O3:Pr3+ depends on the quality of samples [1]. In this paper we study the origin of these holes in Y2O3 with a well-controlled manner. For this purpose, we applied hole-burning spectroscopy to various Y2O3:Pr3+(0.2mol%) samples doped with other metallic ions.
Persistent Hole Burning and Holography in Anthraquinone Derivatives
Authors: Yagyu Eiji , Nishimura Tetsuya , Yoshimura Motomu
Published: February 2023

We have reported persistent spectral hole burning (PHB) in anthraquinone derivatives. 1-3) Hole burning spectroscopy desires high resolution to detect narrow and shallow holes. Laser induced grating (Holography) technique is very effective for the investigation of a shallow hole, because it enables to detect a small signal without a large background. 4-6) In addition, we can achieve many holographic applications: 3D image storage and reconstruction, holographic memory, holographic computing, etc. However, we should note that hole signal represents a diffraction efficiency in holographic detection, not the absorption spectrum. Consequently, material characteristics, hole width, depth, area, Debye-Waller factor, etc., are not directly obtainable using holographic detection.
The High Pressure Effects in Optical Spectra of Impurity Crystals
Authors: Korotaev O.N. , Kolmakov I.P. , Karpov V.P. , Shchanov M.F.
Published: February 2023

It is customary to assume that the optical spectra of glasses have some distinctive features which are caused by two-level systems (TLS) in the host. In the last few years the new data appeared which indicated that TLS can be found in the crystals as well. Among the evidences are the spectral jumps observation in the single molecule spectrum of p-terphenyl doped with pentacene molecular crystal [1], the revealing of the anomalous quasylinear thermal dependency of zero-phonon line halfwidth in the spectra of perylene in n-octane matrices [2,3] etc.
Surface Plasmon Imaging of Ultra-thin LB Films Prepared by Photoreactive Poly(vinyl ocatal acetal)s
Authors: Ito Shinzaburo , Mabuchi Michiaki , Yamamoto Masahide
Published: February 2023

Ultra-thin polymer films prepared by the Langmuir-Blodgett (LB) technique are one of fascinating materials in many fields of applications. Especially, polymer LB films have a lot of advantages as LB materials, for example, fewer pin-hole due to the amorphous character and thinness of each layer due to structural stabilization by the covalent linkage of the hydrophobic units. Furthermore, the chemical structure is easily modified by functional groups, providing various functions to the polymer LB films while keeping the excellent LB characters.
Homogeneous Width of Eu3+ in Silicate Glass Fiber Measured by Accumulated Photon Echoes
Authors: Yano Ryuzi , Uesugi Naoshi
Published: February 2023

The optical homogeneous widths of ions or molecules in glasses exhibit an anomalous behavior in both their magnitude and temperature dependence when compared to the same species in crystals. Many studies of the homogeneous widths of molecules have advanced our knowledge of properties such as low-temperature dephasing and spectral diffusion. However, the mechanisms of the homogeneous widths of ions in glasses are still not fully understood.
Holeburning and Optical/RF Double Resonance Studies of Trigonal Ho3+ Centers in CaF2
Authors: Manson Neil B. , Boonyarith Tosporn , Martin John P. D.
Published: February 2023

Holeburning in the hyperfine lines associated with the trigonal Ho3+ center in CaF2 has been reported previously [1,2,3]. In these studies it was shown that two mechanisms for the observed holeburning are through a redistribution of population within the ground state hyperfine and superhyperfine levels. In this paper, the extent of the hyperfine holeburning storage is discussed using two laser experiments. In addition, the assignment of superhyperfine resonances to particular neighbouring fluorine ions is made and the doublet structure of the superhyperfine resonances is attributed to significant enhancement of the holmium nuclear moment.
Phased-Locked Arrays of Semiconductor Diode Lasers
Authors: Botez Dan
Published: February 2023

Phased-locked arrays of diode lasers have been reported as early as 1978.(1) However, very rarely have the beam patterns of arrays displayed the desired result: a single, diffraction-limited beam in both cw and pulsed operation. Initially, the problem has been that arrays were made of gain-guided devices, that is, devices for which lateral optical-mode confinement is solely provided by the injected-carrier profile. Gain-guided devices are thus intrinsically vulnerable to gain-profile changes due to drive condition changes (i. e. cw or pulsed), spatial hole-burning at high drive levels above threshold, and/or temperature variations across the laser chip. Revealingly, recent studies of arrays of gain-guided lasers(2) show that such devices are more appropriately modeled as broad-area devices with gain perturbations rather than coupled waveguides. Thus, even though output powers as high as 5W have been reported from gain-guided arrays, their beam quality has generally been poor, which removes them as candidates for applications requiring beam-forming optics. While harder to make, arrays of index-guided lasers,(3) that is devices with "built-in" dielectric waveguides, have demonstrated both stable-beam operation under cw and pulsed drive conditions as well as single-longitudinal mode operation. Most recent work has concentrated on the fabrication and mode control of index-guided devices.
Power instability and optical bistability in grating loaded external cavity semiconductor laser
Authors: Kuo Chien-Yu
Published: February 2023

The grating loaded external cavity semiconductor laser is widely used for demonstration of coherent optical fiber communication because of its versatility for tuning and high spectral purity.[1] For heterodyne application, it is desirable that this laser can be stably and continuously tuned through a broad bandwidth. However, the high laser gain and the large medium nonlinearity limit the expected tuning ability when the antireflection coating on the facet facing the grating is less than perfect. In fact, power variation and optical bistability with respect to tuning are expected.[2] We present in this paper an experimental study of the power instability and optical bistability, when the grating and cavity length are not tuned synchronously.
Coherent Beam Combining of One- and Two-Dimensional Laser Arrays
Authors: Leger James R. , Swanson Gary J. , Holz Michael
Published: February 2023

Individual semiconductor lasers are limited in absolute brightness by several physical constraints. Recently, one- and two-dimensional laser arrays have been developed to overcome this limit. In order to achieve the goal of a brighter source however, it is necessary both to establish coherence between the lasers in the array and to provide a method of converting all the laser beams into a single beam.
Vertical cavity surface emitting laser structure in molecular beam epitaxial GaAs - AlGaAs using multilayer dielectric mirror.
Authors: Christensen D.H. , Barnes F.S.
Published: February 2023

Several types of surface emitting laser diodes have been fabricated by various groups: the etched mirror device; the vertical cavity device2, and the second order distributed Bragg reflector device3. Operating characteristics of vertical cavity devices have been poor in comparison to the other surface emitter types, however, some characteristics still make it very attractive in potential applications. With the development of high quality epitaxial multilayers of GaAs and AlGaAs for use as mirrors4 and simultaneously as conducting layers, it should be possible to realize vertical cavity devices which operate continuously and are usable in two dimensional array technology. Theoretically, a packing density of one device per four square mils is realizable and thus when scaling to areal arrays, lower optical output per device at a given operating current may be overcome by increased packing density in high power applications. The fabrication of monolithic arrays in this technology is greatly simplified and does not require difficult processing steps for optical output coupling perpendicular to the wafer. Vertical structures are also attractive in the arena of vertical integration of emitters and intracavity loss devices with applications in two dimensional arrays of optical logic elements or controlled modulation independent of emitter bias.
Impurity-Induced Disordering and Laser Device Applications
Authors: Thomton R. L. , Bumham R. D. , Holonyak N. , Epler J. E. , Paoli T. L.
Published: February 2023

In the five years that have elapsed since the first demonstration of the phenomenon of impurity induced disordering (IID) (Laidig et al 1981) and the obvious implication to integrated optoelectronics (Holonyak et al 1981), considerable effort has been devoted to studying and utilizing this effect. It is becoming increasingly apparent that the effect is an almost universal one, being observed in a wide variety of III-V alloy systems as well as being induced by a wide variety of impurity species. Studies have been carried out using surface diffusion, ion implantation and doping during epitaxial growth. The results of this work indicate that the mechanisms are at least as complicated as the technique is universal.
Long-read sequencing identifies novel structural variations in colorectal cancer
Authors: Xu Luming , Wang Xingyue , Lu Xiaohuan , Liang Fan , Liu Zhibo , Zhang Hongyan , Li Xiaoqiong , Tian ShaoBo , Wang Lin , Wang Zheng
Published: February 2023

Structural variations (SVs) are a key type of cancer genomic alterations, contributing to oncogenesis and progression of many cancers, including colorectal cancer (CRC). However, SVs in CRC remain difficult to be reliably detected due to limited SV-detection capacity of the commonly used short-read sequencing. This study investigated the somatic SVs in 21 pairs of CRC samples by Nanopore whole-genome long-read sequencing. 5200 novel somatic SVs from 21 CRC patients (494 SVs / patient) were identified. A 4.9-Mbp long inversion that silences APC expression (confirmed by RNA-seq) and an 11.2-kbp inversion that structurally alters CFTR were identified. Two novel gene fusions that might functionally impact the oncogene RNF38 and the tumor-suppressor SMAD3 were detected. RNF38 fusion possesses metastasis-promoting ability confirmed by in vitro migration and invasion assay, and in vivo metastasis experiments. This work highlighted the various applications of long-read sequencing in cancer genome analysis, and shed new light on how somatic SVs structurally alter critical genes in CRC. The investigation on somatic SVs via nanopore sequencing revealed the potential of this genomic approach in facilitating precise diagnosis and personalized treatment of CRC.
Beyond social prescribing—The use of social return on investment (SROI) analysis in integrated health and social care interventions in England and Wales: A protocol for a systematic review
Authors: Hopkins Genevieve , Winrow Eira , Davies Ceryl , Seddon Diane
Published: February 2023

With increasing costs of healthcare in England and Wales following the COVID-19 pandemic, finding alternatives to traditional medical interventions is more important than ever. Social prescribing provides a way of addressing health and well-being through using non-medical methods that may help relieve costs to the NHS. Evaluating interventions, such as social prescribing, which have high social (but not easily quantifiable) value, can be problematic. Social return on investment (SROI) is a method of assigning monetary values to both social value as well as traditional assets, so provides a way of evaluating social prescribing initiatives. This protocol outlines the steps that will be taken in a systematic review of the SROI literature surrounding social prescribing-type integrated health and social care interventions based in the community in England and Wales. Online academic databases such as PubMed Central, ASSIA and Web of Science will be searched, as will grey literature sources such as Google Scholar, the Wales School for Social Prescribing Research (WSSPR) and Social Value UK. Titles and abstracts from the articles returned by the searches will be reviewed by one researcher. Those selected for full text review will be independently reviewed and compared by two researchers. Where the researchers disagree a third reviewer will help resolve any differences. Information collected will include identifying stakeholder groups, assessing the quality of SROI analyses, identifying intended and unintended changes of social prescribing interventions, and comparing social prescribing initiatives in terms of SROI costs and benefits. Quality assessment will be independently conducted on the selected papers by two researchers. The researchers will discuss to obtain consensus. Where there is disagreement, a third researcher will resolve these cases. A pre-existing quality framework will be developed and used to assess the quality of the literature.

Protocol registration Prospero registration number: CRD42022318911.
Investigating the distribution of calls to a North American animal poison control call center by veterinarians and the public in space, time, and space-time
Authors: Shahin Keana , Pearl David L. , Berke Olaf , O’Sullivan Terri L.
Published: February 2023

Health assessments via phone call or tele-triage have become very popular. Tele-triage in the veterinary field and North American context is available since the early 2000s. However, there is little knowledge of how caller type influences the distribution of calls. The objectives of this study were to examine the distribution of calls to the Animal Poison Control Center (APCC) by caller type in space, time, and space-time. Data regarding caller location were obtained from the APCC by American Society for the Prevention of Cruelty to Animals (ASPCA). The data were analysed using the spatial scan statistic to identify clusters of higher-than-expected proportion of veterinarian or public calls in space, time, and space-time. Statistically significant spatial clusters of increased call frequencies by veterinarians were identified in some western, midwestern, and southwestern states for each year of the study period. Furthermore, annual clusters of increased call frequencies by the general public were identified from some northeastern states. Based on yearly scans, we identified statistically significant temporal clusters of higher-than-expected public calls during Christmas/winter holidays. During space-time scans of the entire study period, we identified a statistically significant cluster of higher-than-expected proportion of veterinarian calls at the beginning of the study period in the western, central, and southeastern states followed by a significant cluster of excess public calls near the end of the study period on the northeast. Our results suggest that user patterns of the APCC vary by region and both season and calendar time.
Challenges and understandings of creative practice in professional sport training
Authors: Antonini Philippe Roberta , Biasutti Michele , van der Schyff Dylan , Schiavio Andrea
Published: February 2023

We conducted a qualitative study involving twelve expert sports coaches to explore and compare the range of creative practices they adopted during their professional activities. Their written responses to open-ended questions highlighted different interrelated dimensions of creative engagement in coaching sport, suggesting that efforts to instil creativity may initially focus on an individual athlete; they may often span a range of behaviours dedicated to efficiency; they may involve significant degrees of freedom and trust; and they cannot be captured by a single defining feature. We contextualise these findings in the light of recent literature in sports studies, performance science and creativity research, providing concrete examples based on the written statements provided by our participants. We conclude by offering insights for future research and coaching practice that may be relevant in broader domains.
PedaleoVR: Usability study of a virtual reality application for cycling exercise in patients with lower limb disorders and elderly people
Authors: Rojo Ana , Castrillo Arantxa , López Cristina , Perea Luis , Alnajjar Fady , Moreno Juan C. , Raya Rafael
Published: February 2023

Achieving adherence to physical exercise training is essential in elders and adults with neurological disorders. Immersive technologies are seeing wide adoption among new neurorehabilitation therapies, as they provide a highly effective motivational and stimulating component. The aim of this study is to verify whether the developed virtual reality system for pedaling exercise is accepted and could be safety, useful and motivating for these populations. A feasibility study was conducted with patients with neuromotor disorders and elderly people from Lescer Clinic and the residential group Albertia, respectively. All the participants performed a pedaling exercise session with virtual reality platform. Then, the Intrinsic Motivation Inventory, the System Usability Scale (SUS), Credibility and Expectancy Questionnaire, were assessed in the group of 20 adults (mean age = 61.1; standard deviation = 12.617, 15 males and 5 females) with lower limb disorders. While the Simulator Sickness Questionnaire, Presence Questionnaire, Game user Experience Satisfaction Scale and SUS were assessed in the group of 18 elders (mean age = 85.16; standard deviation = 5.93, 5 males and 13 females). In light of the outcomes, PedaleoVR is considered to be a credible, usable and motivational tool towards adults with neuromotor disorders to perform cycling exercise, and therefore its usage could contribute to adherence to lower limb training activities. Moreover, PedaleoVR does not generate negative effects related to cybersickness while the sensation of presence and the degree of satisfaction generated have been positively evaluated by the geriatric population. This trial has been registered at ClinicalTrials.gov under the identifier: NCT05162040, Dec 2021
Predicting mortality after start of long-term dialysis–International validation of one- and two-year prediction models
Authors: Haapio Mikko , van Diepen Merel , Steenkamp Retha , Helve Jaakko , Dekker Friedo W. , Caskey Fergus , Finne Patrik
Published: February 2023

Background

Mortality prediction is critical on long-term kidney replacement therapy (KRT), both for individual treatment decisions and resource planning. Many mortality prediction models already exist, but as a major shortcoming most of them have only been validated internally. This leaves reliability and usefulness of these models in other KRT populations, especially foreign, unknown. Previously two models were constructed for one- and two-year mortality prediction of Finnish patients starting long-term dialysis. These models are here internationally validated in KRT populations of the Dutch NECOSAD Study and the UK Renal Registry (UKRR).

Methods

We validated the models externally on 2051 NECOSAD patients and on two UKRR patient cohorts (5328 and 45493 patients). We performed multiple imputation for missing data, used c-statistic (AUC) to assess discrimination, and evaluated calibration by plotting average estimated probability of death against observed risk of death.

Results

Both prediction models performed well in the NECOSAD population (AUC 0.79 for the one-year model and 0.78 for the two-year model). In the UKRR populations, performance was slightly weaker (AUCs: 0.73 and 0.74). These are to be compared to the earlier external validation in a Finnish cohort (AUCs: 0.77 and 0.74). In all tested populations, our models performed better for PD than HD patients. Level of death risk (i.e., calibration) was well estimated by the one-year model in all cohorts but was somewhat overestimated by the two-year model.

Conclusions

Our prediction models showed good performance not only in the Finnish but in foreign KRT populations as well. Compared to the other existing models, the current models have equal or better performance and fewer variables, thus increasing models’ usability. The models are easily accessible on the web. These results encourage implementing the models into clinical decision-making widely among European KRT populations.
The future(s) of unpaid work: How susceptible do experts from different backgrounds think the domestic sphere is to automation?
Authors: Lehdonvirta Vili , Shi Lulu P. , Hertog Ekaterina , Nagase Nobuko , Ohta Yuji
Published: February 2023

The future of work has become a prominent topic for research and policy debate. However, the debate has focused entirely on paid work, even though people in industrialized countries on average spend comparable amounts of time on unpaid work. The objectives of this study are therefore (1) to expand the future of work debate to unpaid domestic work and (2) to critique the main methodology used in previous studies. To these ends, we conducted a forecasting exercise in which 65 AI experts from the UK and Japan estimated how automatable are 17 housework and care work tasks. Unlike previous studies, we applied a sociological approach that considers how experts’ diverse backgrounds might shape their estimates. On average our experts predicted that 39 percent of the time spent on a domestic task will be automatable within ten years. Japanese male experts were notably pessimistic about the potentials of domestic automation, a result we interpret through gender disparities in the Japanese household. Our contributions are providing the first quantitative estimates concerning the future of unpaid work and demonstrating how such predictions are socially contingent, with implications to forecasting methodology.
Do cash transfers alleviate common mental disorders in low- and middle-income countries? A systematic review and meta-analysis
Authors: Wollburg Clara , Steinert Janina Isabel , Reeves Aaron , Nye Elizabeth
Published: February 2023

A large literature has demonstrated the link between poverty and mental ill-health. Yet, the potential causal effects of poverty alleviation measures on mental disorders are not well-understood. In this systematic review, we summarize the evidence of the effects of a particular kind of poverty alleviation mechanism on mental health: the provision of cash transfers in low- and middle-income countries. We searched eleven databases and websites and assessed over 4,000 studies for eligibility. Randomized controlled trials evaluating the effects of cash transfers on depression, anxiety, and stress were included. All programs targeted adults or adolescents living in poverty. Overall, 17 studies, comprising 26,794 participants in Sub-Saharan Africa, Latin America, and South Asia, met the inclusion criteria of this review. Studies were critically appraised using Cochrane’s Risk of Bias tool and publication bias was tested using funnel plots, egger’s regression, and sensitivity analyses. The review was registered in PROSPERO (CRD42020186955). Meta-analysis showed that cash transfers significantly reduced depression and anxiety of recipients (dpooled = -0.10; 95%-CI: -0.15, -0.05; p<0.01). However, improvements may not be sustained 2–9 years after program cessation (dpooled = -0.05; 95%-CI: -0.14, 0.04; ns). Meta-regression indicates that impacts were larger for unconditional transfers (dpooled = -0.14; 95%-CI: -0.17, -0.10; p<0.01) than for conditional programs (dpooled = 0.10; 95%-CI: 0.07, 0.13; p<0.01). Effects on stress were insignificant and confidence intervals include both the possibility of meaningful reductions and small increases in stress (dpooled = -0.10; 95%-CI: -0.32, 0.12; ns). Overall, our findings suggest that cash transfers can play a role in alleviating depression and anxiety disorders. Yet, continued financial support may be necessary to enable longer-term improvements. Impacts are comparable in size to the effects of cash transfers on, e.g., children’s test scores and child labor. Our findings further raise caution about potential adverse effects of conditionality on mental health, although more evidence is needed to draw robust conclusions.