bluuebunny/crossref_metadata_2025 huggingface dataset:
Glaucomatous Dysfunction Revealed in Higher Order Components of the Electroretinogram
Authors: Bearse Marcus A. , Sutter Erich E. , Sim Daniel , Stamper Robert
Published: February 2023

Ganglion cells of the retina, whose axons comprise the optic nerve fibers, are lost in glaucoma. To help estimate the extent of ganglion cell loss in the clinic and to establish a diagnosis of glaucoma, measurement of the cup-to-disk ratio of the optic nerve head and psychophysical perimetry are used. These methods can only detect loss after it occurs, however, and up to 40% of the ganglion cells may be lost before visual field defects appear in perimetry1.
The effect of ocular parasympathectomy and sympathectomy on diurnal choroidal thickness changes in chicks measured with laser Doppler interferometry
Authors: Schmid G.F. , Papastergiou G.I. , Riva C.E. , Lin T. , Stone R.A. , Laties A.M.
Published: February 2023

Laser Doppler interferometry (LDI) is a precise and noninvasive method to measure intraocular distances in vivo.1 The appearance of several distinct components of the interference signal likely corresponding to reflections from the inner limiting membrane (ILM), retinal pigment epithelium (RPE) and the posterior surface of the sclera (Fig. 1) permits a thickness analysis of fundus layers. We defined the distance from the ILM to the RPE as retinal thickness and the distance from the cornea to the outer sclera as axial length. The distance from the RPE to the outer sclera includes the thicknesses of both the choroid and the sclera. Because the chick sclera is made of cartilage and connective tissue, it is unlikely to exhibit daily thickness fluctuations. We therefore assumed that daily fluctuations in the distance from the RPE to the outer sclera are due chiefly to choroidal thickness changes. The instrument measures optical distances. Geometrical distances are obtained by dividing the optical distances by the refractive index of the ocular media.
Perception of color fringes applied to ophthalmic lenses
Authors: Bar Nathalie , Miege Christian
Published: February 2023

Ophthalmic lenses wearers ask for thinner and more attractive lenses. This is now possible thanks to the recently developed, high-index plastic materials. But these new materials are also characterised by a low Abbe Number or low optical constringence.
Patient Acceptance of Auto-Refractor and Clinician Prescriptions: A Randomized Clinical Trial
Authors: Bullimore Mark A. , Adams Craig W. , Fusaro Robert E. , Bauman Marcella , Cotteral Russell M. , Ng Sarver Joy , Twelker J. Daniel , Graham Andrew D.
Published: February 2023

Auto-refractors are frequently used to provide a starting point for subjective examinations. Ancillary personnel use auto-refractors to obtain rapid estimates of patients' refractive errors which can then be refined by clinicians. Automated refraction has also found use in studies of refractive error (e.g., Zadnik et al., 1993), due to its superior repeatability to clinician refraction (Zadnik et al., 1992; Adams et al., 1995).
Apodization, Point Spread Variance, and Wave Front Variance
Authors: Howland Howard C. , Applegate Raymond A.
Published: February 2023

Apodization influences the intensity of rays passing through various portions of the pupil aperture. In a ray-tracing computation of the point spread, each ray at the image plane is weighted by the apodizing factor of the portion of the pupil through which it passed. In computing the variance, or second moment, of the point spread, for example, the squares of the distances of the rays from the center of the point spread are weighted by the apodizing factor associated with the portion of the pupil through which they passed, e.g, Stiles-Crawford apodization (1,2): Here we seek to find an attenuation of the wave aberration at the pupil, using a function of the apodizing factor that would result in a point spread of variance equivalent to that of the apodized unattenuated aberrated wave.
Spatial Frequency Channels Revealed by Individual Differences in Contrast Sensitivity Functions: Visual Evoked Potentials from Adults and Infants
Authors: Peterzell David H. , Kelly John P.
Published: February 2023

The processes underlying the contrast senstivity functions (CSFs) of human adults are generally understood. Multiple spatial channels, selective for spatial frequency, have been found using sinewave gratings (Graham, 1989; De Valois & De Valois, 1988).
Effect of Cold Provocation on the Visual Fields of Subjects with Raynaud’s Phenomenon and Normal Controls
Authors: Chauhan Balwantray C. , Rathee Rajinder S. , Mosher Dianne , Maxner Charles E. , MacDonald Christine A. , McCormick Terry A.
Published: February 2023

Vasospasm is defined as contraction or hypertonia of the muscular coats of blood vessels. It may result in decreased blood flow to perfused tissues followed by reversible ischemia of varying severity. Vasospasm is present and believed to be a pathogenetic factor in many diseases such as Raynaud’sphenomenon, migraine, and Prinzmetal’s variant angina.1 Cold is known to provoke spasm, as are nicotine and emotional or physical stress.
A Mathematical Model of a Placido Disk Keratometer and its Implications for Recovery of Corneal Topography
Authors: Rand Richard , Applegate Raymond A. , Howland Howard C.
Published: February 2023

We derive and obtain approximate solutions to the equations for a placido disk keratometer relating the ring targets to their images. In addition, we present corneal surfaces that cannot be determined solely by the use of placido ring images, but rather that require for their determination radial elements in the target pattern.
Effects of Unequal Competition on Visual Development Can Be Minimized By Treatment of Congenital Unilateral Cataract During The First Eight Weeks of Life
Authors: Birch Eileen E. , Stager David , Leffler Joel , Weakley David
Published: February 2023

Adverse effects of dense congenital unilateral cataracts on the developing visual system of infants may result from the direct effects of visual deprivation and, in addition, as a result of competition with the normal eye in establishing cortical structure and function during a critical period in visual development. One approach to evaluating these two amblyogenic factors has been to compare the effects of unilateral and bilateral cataracts on visual development. The rationale is that a developing visual system with dense bilateral cataracts suffers only the effects of early visual deprivation while the developing visual system with a dense unilateral cataract suffers the effects of visual deprivation and of competition with a normal eye.
Insufficient Accommodation: Does It Occur Before The Onset Of Myopia In Children?
Authors: Gwiazda Jane , Bauer Joseph , Thorn Frank , Grice Kenneth
Published: February 2023

Reduced blur-driven accommodation has been linked to the development and progression of juvenile-onset myopia (Goss, 1991; Goss and Jackson, 1996; Gwiazda et al, 1993, 1995). While both laboratory and clinical studies have reported that this condition occurs concomitantly with progressing myopia, less evidence is available as to whether or not it occurs before myopia onset. Obviously, the identification of predictive factors has important implications for treatment and prevention of myopia, as well as for establishing the temporal order of causal mechanisms.
Form Vision Deprivation Still Induces Axial Elongation and Myopic Shift In One Year Old Chickens
Authors: Papastergiou Georgios I. , Schmid Gregor F. , Riva Charles E. , Lin Ton , Stone Richard A. , Laties Alan M.
Published: February 2023

It has been shown in numerous studies that axial eye elongation and myopia can be induced in young experimental animals by depriving their developing eyes of high contrast and form vision using plastic, translucent goggles or lid suture. Previous studies in chickens,1 tree shrews 2 and monkeys 3 suggest that the susceptibility to form vision deprivation (the amount of myopia induced per time) is at a maximum during early neonatal life (after hatching in chicks, 15 days after eye opening in tree shrews) and declines rapidly with age. The relevance of these findings to human juvenile myopia, however, has not been demonstrated. First, human myopia usually starts to develop later in life, predominantly between 8-16 years, in many cases after the eye has fully grown.4 Second, visual conditions similar to those during form vision deprivation are rarely eperienced by young humans. Thus the mechanism(s) producing juvenile human myopia may be different from the mechanism(s) producing goggle induced myopia in young animals. In fact, late onset juvenile myopia is likely not related to form deprivation myopia at all.
Assessment of Lateral Interaction Across the Visual Field Using Hermann Grid Contrast Thresholds
Authors: Comerford James P. , Perryman Steve , Pruszenski Amy , Thorn Frank , Held Richard
Published: February 2023

We have developed several psychophysical measures that may reflect the neuropharmacological control of center-surround interactions within the human visual system (Comerford et al 1990, 1991). We have been particularly interested in patients with Parkinson’s disease, a disease associated with destruction of the dopaminergic neurons of the Substantia Nigra (Comerford et al 1995). Recent evidence suggests that this disease also affects the dopaminergic neurons of the retina (Nguyen-Legros 1988). These retinal neurons release dopamine maximally under photopic conditions and are associated with an increase in surround inhibition in the center-surround balance of retinal receptive fields.
A spectral analysis of eye movement disturbances in children suffering from congenital cataract
Authors: Popovic Zoran , Thaung Jörgen , Abrahamsson Maths
Published: February 2023

Congenital cataract is one of the most common causes of congenital visual disability. Congenital cataract manifests itself with different qualities and densities, but one thing that applies to all types is that a blurring of the optics of the eye prevents the projection of a clear image on the retina.
Gaze Stabilization in Six Degrees of Freedom During Natural Movements
Authors: Crane Benjamin T. , Demer Joseph L.
Published: February 2023

The purpose of the vestibulo-ocular reflex (VOR) is to stabilize images on the retina during movement. A common, idealized concept of the angular VOR is that is generates ocular rotational eye velocity equal and opposite that of the head, so that angular gaze velocity in space remains near zero. Thus, in most prior studies, results are stated in terms of gain of the VOR, defined as compensatory angular eye velocity divided by the angular head velocity. A gain of unity in this simplification would perfectly stabilize gaze. The implicit assumption, however, is that head motion consists only of rotation of the orbit without translation. We show here that this assumption is generally quite erroneous, since significant orbital translation is an intrinsic concomitant to the incidental head rotations resulting from natural activities. Further, these disturbances of gaze stability consist of integrated movement patterns in all six degrees of freedom.
Reading Rate With RSVP is Affected by Font at a Low Luminance But Not at a High Luminance
Authors: Aquilante Kathy , Plass Robert J. , Yager Dean , Shoykhet Dina , Siciliano Antonia
Published: February 2023

Miles A. Tinker defined legibility as the perception of letters, words and continuous text for reading: “The shapes of letters must be discriminated, the characteristic word forms perceived, and continuous text read accurately, rapidly, easily, and with understanding. In the final analysis, one wants to know what typographical factors foster ease and speed of reading” (Tinker, 1963).
The Slope of Frequency-of-Seeing Curves in Normal, Amblyopic and Pathologic Vision
Authors: Demirel Shaban , Johnson Chris A. , Fendrich Robert , Vingrys Algis J.
Published: February 2023

It has long been known that threshold variability is increased in glaucoma.1 Furthermore, it has been suggested that increased variability may be one of the earliest signs of visual dysfunction in this disease.1-3 There is debate, as to the mechanisms responsible for the increased variability. One theory suggests that increased variability is due to a reduced signal to noise ratio in diseased neurons. Another theory asserts that increased variability is due in part to eye movements, whereby small fixation shifts allow retinal areas with vastly different sensitivities to contribute to the measured threshold.4-6 The current study controlled the effect of fixation shifts by producing retinally stabilized stimuli. Psychometric variability was defined in terms of the slope of frequency-of-seeing (FOS) curves generated using a method of constant stimuli (MOCS) paradigm.
Photoreceptor Directionality at Different Wavelengths: Measurements and Predictions
Authors: Marcos Susana , He Ji Chang , Burns Stephen A.
Published: February 2023

Cone photoreceptors are typically more sensitive to light entering the eye through the center of the pupil than to light coming from the edges of the pupil.
Developing Vision Standards for the Canadian Forces: Seeing All That They Can See
Authors: Casson E. J. , Gibbs Gillian H.
Published: February 2023

According to both the Canadian Human Rights Act and the American
Disabilities Act, a valid vision standard is one that establishes
through objective means, a minimum level of vision required by the
essential tasks of an occupation. Such a standard must be set to
ensure that the necessary visual qualifications are met to preserve
good job performance and public safety without unnecessarily excluding
qualified applicants.
Testing Vision Beyond Legal Blindness: Early Beginnings of a Visual Function Test Battery
Authors: Dagnelie Gislin
Published: February 2023

Retinal degenerative diseases place a severe burden on the quality of life of over 100,000 young and working age individuals, and seriously threaten the independence and health of several million elderly persons in the United States alone.
A Videokeratoscope Using a Distorted Checkerboard Target
Authors: Schwiegerling Jim , Miller Joseph M.
Published: February 2023

The majority of commercially available videokeratoscopes use Placido disk technology.
Testing the Campbell-Green Equation Using MTF and CS Data from Normal and Cataractous Eyes
Authors: Balaram M , Ragavan A , Tung W , Chylack L , Magnante P
Published: February 2023

Good vision requires the proper function of two pathways: 1) the optical pathway which extends from the cornea to the retinal photoreceptors, and 2) the neural pathway which extends from the photoreceptors to the brain. In a clinical study of patients with both normal and cataractous eyes, we have investigated how the optical and neural components together contribute to vision by testing the Campbell-Green equation, CStot = CSneur * MTF.1 CStot represents the contrast sensitivity function determined by chart testing. CSneur is the neural contrast sensitivity function. MTF is the optical modulation transfer function.
Relation between Self-Perceived Status of Visual Functioning (VF-14) and Indices of Functional Vision Derived from Visual Acuity Measurements
Authors: Fontaine N. , Gresset J. , Boisjoly H. M. , Brunette I. , Le François M. , Deschênes J. , Bazin R. , Laughrea P.A. , Dubé I. , Charest M.
Published: February 2023

Many sources have advocated the use of indices of functional vision to measure the severity of visual impairment and their consequences on the quality of life. Different methods have been proposed. Traditional methods rely on monocular or binocular visual acuity (VA). The severity scale of impairment of the World Health Organisation1 is based on the best-eye VA and/or on the visual field. Other methods use various combinations of monocular VA (expressed as percentages) to calculate "weighted binocular scores", as proposed by the American Medical Association2 or Colenbrander3. A more recent approach, relies on the self-perceived status of visual functioning as measured by vision-related questionnaires. A variety of instruments have been devised to assess vision-targeted functional performance associated with visual impairment in subjects with cataract4-7. Of these, the Visual Functioning Index (VF-14) is one of the most widely used. The reliability, validity as well as the responsive ness of the VF-14 has been well documented in the case of cataract surgery7-10. In addition, this questionnaire has recently been validated for the evaluation of corneal and other ocular diseases11, 12
On the Generation of Spherical Aberration and Coma of Variable Magnitude
Authors: López-Gil Norberto , Howland Bradford , Charman Neil , Applegate Raymond , Howland Howard C.
Published: February 2023

With so much interest being shown on the monochromatic aberrations of the eye, it is perhaps remarkable that few have studied their effect on vision. Besides spherical aberration and astigmatism there are not many studies on the influence of the third and four order wave aberration in vision. Part of the reason for this must lie in the difficulty of first measuring the high order aberrations of the eye and, secondly, introducing monochromatic aberrations of known quantity into a system incorporating the human eye as a sensor.
Experimental quantum information processing with atoms and photons
Authors: Pan Jian-Wei
Published: February 2023

Quantum information science and atom optics are among the most active fields in modem physics. In recent years, many theoretical efforts have been made to combine these two fields. Recent experimental progresses [1-3] have shown the in-principle possibility to perform scalable quantum information processing (QIP) with linear optics and atomic ensembles [4]. One of our main activities is to use atomic qubits as quantum memory and exploit photonic qubits for information transfer and processing to achieve efficient linear optics QIP. On the one hand, utilizing the interaction between laser pulses and atomic ensembles we experimentally investigate the potentials of atomic ensembles in the gas phase to build quantum repeaters for longdistance quantum communication [5], that is, to develop a new technological solution for quantum repeaters making use of the effective qubit-type entanglement of two cold atomic ensembles by a projective measurement of individual photons by spontaneous Raman processes. On the other hand, building on our long experience in research on multi-photon entanglement, we are also working on a number of experiments in the field of QIP with particular emphasis on fault-tolerant quantum computation [6], photon-loss-tolerant quantum computation [7] and cluster-state based quantum simulation [8]. In future, by combining the techniques developed in the above quantum memory and multi-photon interference experiments, we will experimentally investigate the possibility to achieve quantum teleportation between photonic and atomic qubits, quantum teleportation between remote atomic qubits and efficient entanglement generation via classical feed-forward. The techniques that are being developed will lay the basis for future large-scale realizations of linear optical QIP with atoms and photons.
Entanglement and Decoherence
Authors: Davidovich Luiz
Published: February 2023

The interaction between entangled multi-particle systems with the environment leads to both local dynamics, associated with single-particle dissipation, diffusion, and decay, and to global dynamics, which may provoke the disappearance of entanglement at a finite time [1-6]. This phenomenon may occur even when single-particle decoherence is asymptotic in time, and constitutes yet another distinct trait of entanglement. It has been recently demonstrated, for two qubits under the action of independent environments, using an all-optical setup [7]. In this talk, some of the peculiarities of the dynamics of two-qubit entangled states undergoing decoherence will be reviewed, new features of the experiment realized at the Federal University of Rio de Janeiro [7] will be described, and the extension of these considerations to multi-particle entangled states will be discussed. Scaling laws for the decay of entanglement and its finite-time extinction in multi-particle systems will be discussed.
Macroscopic EPR paradoxes
Authors: Reid M. D. , Cavalcanti E. G.
Published: February 2023

We propose to test the inconsistency of local reality with quantum mechanics progressively, by defining the S-scopic EPR paradox, that would ultimately allow test of the EPR paradox for the macroscopically entangled "Schrodinger cat" state. Practical signatures of the S-scopic EPR-entanglement are presented for several experimental prototypes.
Quantum Brownian motion of a macroscopic object in a general environment
Authors: Chou Chung-Hsien
Published: February 2023

For the purpose of understanding the quantum behavior such as quantum decoherence, fluctuations, dissipation, entanglement and teleportation of a mesoscopic or macroscopic object interacting with a general environment, we derive here a set of exact master equations for the reduced density matrix of N interacting harmonic oscillators in a heat bath with arbitrary spectral density and temperature. For the case N = 2, we also give an influence functional treatment of this model and provide explicit expressions for the evolution operator of the reduced density matrix which are useful for the study of decoherence and disentanglement issues. We show a simple application of this master equation by examining the decoherence and disentanglement of two harmonic oscillators due to their interaction with a common environment under Markovian approximation. Two classes of problems of interest to us which these equations can be usefully applied to are that of the quantum dynamics of nanoelectromechanical oscillators and the entanglement evolution of multi-partite macroscopic states such as quantum superposition of mirrors in a high Q cavity. To address a key conceptual issue for macroscopic quantum phenomena we examine the conditions for an assumption often implicitly made in these studies to be valid, namely, that the quantum behavior of a macroscopic object in an environment can be accurately represented by only treating the dynamics of its center-of-mass variable. We also mention how these results can be used to calculate the uncertainty principle governing a macroscopic object at finite temperature.
Quantum Entanglement under Non-Markovian Dynamics of Two Qubits Interacting with a Common Electromagnetic Field*
Authors: Anastopoulos C. , Shresta S. , Hu B. L.
Published: February 2023

We study the non-equilibrium dynamics of a pair of qubits made of two-level atoms separated in space with distance r and interacting with one common electromagnetic field but not directly with each other. Our calculation makes a weak coupling assumption, but no Born or Markov approximation. We derived a non-Markovian master equation for the evolution of the reduced density matrix of the two-qubit system after integrating out the electromagnetic field modes. It contains a Markovian part with a Lindblad type operator and a nonMarkovian contribution, the physics of which is the main focus of this study. We use the concurrence function as a measure of quantum entanglement between the two qubits. Two classes of states are studied in detail: Class A is a one parameter family of states which are the superposition of the highest energy |I〉 ≡ |11〉 and lowest energy |O〉 ≡ |00〉 states, υiz,
|A〉≡p|I〉+(1−p)|O〉, with 0 ≤ p ≤ 1; and Class B states |B〉 are linear combinations of the symmetric
|+〉=12(|01〉+|10〉) and the antisymmetric
|−〉=12(|01〉−|10〉) Bell states.
Dynamics of a superconducting qubit coupled to quantum two-level systems in its environment
Authors: Johansson J.R. , Ashhab S. , Zagoskin A.M. , Nori F.
Published: February 2023

We study the decoherence dynamics of a superconducting qubit coupled to a quantum two-level system (TLS) in addition to its weak coupling to a background environment [1]. We identify two weak-coupling regimes, which differ by the relation between qubit and TLS decoherence times, and a strong coupling regime. We find expressions for the qubit decoherence rates in the weak-coupling regimes. For a weakly coupled and strongly dissipative TLS we find that the qubit dynamics is markovian, whereas for a weakly dissipative TLS the qubit dynamics shows non-markovian behavior. In the strong-coupling regime we study the driven qubit dynamics and we analyze the differences from standard Rabi-oscillations due to the coupling to the quantum TLS [2]. In doing so we identify signatures in the qubit dynamics that can be used to characterize the TLS. We also investigate the possibility of using environmental TLSs with long coherence times for quantum information processing [3]. By using the Josephson junction as a bus and the TLSs in the environment as qubits, we demonstrate that initialization, a universal set of quantum gates, and read-out of the TLSs can be implemented, even though the TLSs themselves cannot be directly accessed.
Master Equation in the Presence of Initial Correlation with Reservoir
Authors: Yuasa Kazuya
Published: February 2023

We discuss the derivation of master equation when there exists an initial correlation between the system and the reservoir. The mixing property of the reservoir dynamics is crucial.
High-Speed Fiber Switches
Authors: Margulis Walter , Tarasenko Oleksandr , Yu Zhangwei , Fonjallaz Pierre-Yves , Knape Harald
Published: February 2023

All-fiber optical switches based on fiber with electrodes exhibit transition times <10 ns. The devices are monolithic and robust, they are simple and could potentially be manufactured at low cost. The insertion loss is extremely low and the devices are compatible with single mode fiber technology. Two types of switches are discussed, one based on polarization rotation, the other one relying on the wavelength shift of a fiber Bragg grating (FBG).
The Acousto-Optic Effect in Microstructured Optical Fibers
Authors: Pohl Alexandre A. P. , Oliveira Roberson A. , Cook Kevin , Canning John
Published: February 2023

The acousto-optic effect has been successfully used since the early 80's in the design and construction of a variety of conventional optical fiber devices such as frequency shifters, couplers, filters and modulators. Acoustic waves can be employed to modulate the spectrum and switch the wavelength of conventional fiber Bragg gratings as well as for controlling the Q-switching in distributed fiber lasers. Tunable devices induced by acoustic waves have also been demonstrated in photonic crystal fibers (PCF), whereas a resonance dip corresponding to an excited cladding mode can be tuned over the wavelength. In a similar work, but inducing an acoustic excitation over the longitudinal axis, long period gratings can be created in the transmission band of a solid core PCF. Recently, the availability of Bragg gratings in photonic crystal fibers enables several applications, particularly if their properties can be controlled in order to produce modulation or allow tunability. A way of achieving these effects is through the excitation of acoustic waves in the fibre, which allows a rapid method for shifting or modulating tie Bragg wavelength. In this work the application of acoustic-waves to microstructured fibers is reviewed and recent results on the modulation of fiber Bragg gratings in photonic crystal fibers are presented.
Optical Frequency Combs Generated by Four-Wave Mixing in Optical Fibers for Astrophysical Spectrometer Calibration and Metrology
Authors: Cruz Flavio C.
Published: February 2023

Optical frequency combs generated by multiple four-wave mixing in optical fibers are proposed for use as high precision frequency markers, calibration of astrophysical spectrometers and metrology. Possible schemes involve two optical frequency standards as input lasers, or one standard and a second laser phase-locked to it using a microwave reference oscillator. Use of highly nonlinear or photonic crystal fibers with very short lengths and small group velocity dispersion, combined with energy and momentum conservation required by the parametric generation, assures negligible phase mismatch between comb frequencies. In contrast to combs from mode-locked lasers or microcavities, the absence of a resonator allows large tuning of the frequency spacing from tens of gigahertz to beyond teraHertz.
Post-Processed Micro-Structured Optical Fibre Sensors
Authors: Finazzi Vittoria , Villatoro Joel , Pruneri Valerio
Published: February 2023

We will report on the development of optical sensors based on post-processing of conventional and photonic crystal fibres. In particular possible schemes of sensor heads for harsh environment and biological analysis will be presented.
Fiberoptic Applications in Sensors and Telemetry for the Electric Power Industry
Authors: Werneck M. M. , Silva A. V. , Souza N. C. C. , Miguel M. A. L. , Beres C. , Yugue E. S. , Carvalho C. C. , Maciel F. L. , Silva-Neto J. , Guimarães C. R. F. , Allil R. C. S. B. , Baliosian J. A. G.
Published: February 2023

This presentation features the origin and the work of the Photonics and Instrumentation Laboratory (LIF) in instrumentation, fiberoptic sensors and POF technology. LIF started its work in 1986, twenty and two years ago, with only one lecturer and a few students. The first project was the development of the first Brazilian plotter with the purpose, at the time, to substitute expensive imported technology. LIF has today 25 people between students, technicians, scientists, engineers and teachers. We present here several successful projects of fiberoptic sensors using both silica and POF fibers, most of them applied on the field mainly for the electric power industry. Described are: a oil leakage sensor in petroleum hoses, PMMA evanescent sensors, temperature by the ruby fluorescence phenomenon, a current sensor calibrator for 500 kV current transformers, a leakage sensor to measure 500 kV insulators in extra-high voltage transmission line, etc. Many of the sensors presented here have been tested in the field, patented and transferred to the industry. We have also technical collaboration with several industries in Brazil, one of them a spin-off from LIF. Our objective is to become a reference centre in POF technology in Latin America and for this we are intended to keep producing “out of the shelves” POF technology and innovative industry solutions for many areas.
All-fiber Devices Based on Photonic Crystal Fibers with Integrated Electrodes
Authors: Chesini Giancarlo , Cordeiro Cristiano M.B. , de Matos Christiano J.S. , Fokine Michael , Carvalho Isabel C.S. , Knight Jonathan C.
Published: February 2023

A special kind of microstructured optical fiber was proposed and manufactured where, as well as the holey region (solid core and silica-air cladding), the fiber has also two large holes for electrode insertion. Bi-Sn and Au-Sn alloys were selectively inserted in those holes forming two parallel, continuous and homogeneous internal electrodes. We demonstrated the production of a monolithic device and its use to externally control some of the guidance properties (e.g. polarization) of the fiber.
Six Degree Freedom Optical Fiber Accelerometer
Authors: Cazo Rogerio Moreira , Ribeiro Erik dos Reis , Nunes Marcelo Buonocore , Barbosa Carmem Lucia , de Siqueira Ferreira Jorge Luis , de Barros Caldas Tales , Santos Josemir Coelho dos , de Arruda Josiel Urbaninho
Published: February 2023

Linear accelerations measurements are needed in many applications, as industry, military, aircrafts, space navigation, robotics and others. Actually, the most usual solutions to measure linear accelerations are three piezoelectric sensors used in orthogonal mounting, or MEM’s sensors chips.

Angular accelerations also are interesting to control and stabilize structures, like satellites and servo motors. It is possible to measure angular accelerations in two ways: direct measurement (using special sensors), or indirect measurements (obtaining acceleration of the angular velocity information) [1].

This work intends to present the structural and optical requirements of a six degree freedom opto-mechanical accelerometer based on fiber Bragg grating (FBG). With this sensor, it will be possible the direct measurement of three axial accelerations, and of three angular accelerations, with unlimited rotation angle, using one single proof mass. The FBG’s are used as strain sensors and sustaining elements of the proof mass in the structure. Simulations have demonstrated that cross influences of 10 parts per million at worst case are possible. This kind of accelerometer may be used in navigation control, structural monitoring, satellite stabilization, guidance control and harsh environments, for example.

The project requirements include the wavelength of FBG’s, pre-strain and length of active segment of optical fibers, dimensions, material and structure of inertial proof mass and position of the fibers in the sustaining structure
Simple and Temperature-Insensitive Pressure Sensing Based on a Hollow-Core Photonic Crystal Fiber
Authors: de Oliveira Rafael Euzebio P. , de Matos Christiano J. S. , Grigoleto Juliano , Cordeiro Cristiano M. B.
Published: February 2023

The sensitivity to pressure of lossy air-guided modes in a commercial hollow-core photonic crystal fiber was experimentally exploited to develop a novel pressure sensor. The transmission of these modes was directly modulated by the measurand, which makes the interrogation system very simple. Using a supercontinuum source, these specific modes were identified within the visible spectral range and correspond to narrow transmission windows well away from the fiber’s main bandgap, centered around 1550 nm. The origin of these windows is being investigated but is likely to be related to cladding bandgaps. One of these windows, around 633 nm, was used for the analysis presented in this paper. An attenuation increase was observed when pressure was applied to a ~3-cm long cell, which was traversed by the fiber. The attenuation reached 5 dB with 300 kgf/cm2 gauge pressure. The transmission was found to be insensitive to temperature up to 100%, which is a highly attractive feature for sensing applications. It was also found that much higher sensitivities (a few dB attenuation with ~0.5 kgf/cm2 gauge pressure) could be obtained when pressure was internally applied to the fiber microstructure. This fact allows for the construction of sensors with a wide range of sensitivities, which can, thus, suit different applications. Transmission within the infrared bandgap was insensitive to pressure and can serve as a reference.
Numerical and Experimental Studies for a High Pressure Photonic Crystal Fiber Based Sensor
Authors: Hayashi Juliano G. , Cordeiro Cristiano M. B. , Franco Marcos A. R. , Sircilli Francisco
Published: February 2023

We report a study of using photonic crystal fibers (PCFs) for high pressure applications. An opto-mechanical analysis was realized in regular PCFs and suspended-core microstructured optical fibers for different fiber geometrical parameters. It was found that the pressure sensitivity is highly dependent on the fiber structure. It was also experimentally shown that even small core PCFs with high air filling fraction can deal with pressures as high as 500 bar (7350 psi) without any noticeable problem.
High Power Fibre-Integrated Supercontinuum Sources
Authors: Cumberland B.A. , Rulkov A. B. , Travers J. C. , Popov S.V. , Taylor J.R.
Published: February 2023

High average power supercontinua are described both picosecond and cw laser pumped. Techniques are described for enhancing the short wavelength extent of the supercontinua and spectral power densities up to 100mW/nm have been achieved.
A behavioral and modeling study of control algorithms underlying the translational optomotor response in larval zebrafish with implications for neural circuit function
Authors: Holman John G. , Lai Winnie W. K. , Pichler Paul , Saska Daniel , Lagnado Leon , Buckley Christopher L.
Published: February 2023

The optomotor response (OMR) is central to the locomotory behavior in diverse animal species including insects, fish and mammals. Furthermore, the study of the OMR in larval zebrafish has become a key model system for investigating the neural basis of sensorimotor control. However, a comprehensive understanding of the underlying control algorithms is still outstanding. In fish it is often assumed that the OMR, by reducing average optic flow across the retina, serves to stabilize position with respect to the ground. Yet the degree to which this is achieved, and how it could emerge from the intermittent burst dynamics of larval zebrafish swimming, are unclear. Here, we combine detailed computational modeling with a new approach to free-swimming experiments in which we control the amount of visual feedback produced by a given motor effort by varying the height of the larva above a moving grid stimulus. We develop an account of underlying feedback control mechanisms that describes both the bout initiation process and the control of swim speed during bouts. We observe that the degree to which fish stabilize their position is only partial and height-dependent, raising questions about its function. We find the relative speed profile during bouts follows a fixed temporal pattern independent of absolute bout speed, suggesting that bout speed and bout termination are not separately controlled. We also find that the reverse optic flow, experienced when the fish is swimming faster than the stimulus, plays a minimal role in control of the OMR despite carrying most of the sensory information about self-movement. These results shed new light on the underlying dynamics of the OMR in larval zebrafish and will be crucial for future work aimed at identifying the neural basis of this behavior.
Strategies to investigate and mitigate collider bias in genetic and Mendelian randomisation studies of disease progression
Authors: Mitchell Ruth E. , Hartley April E. , Walker Venexia M. , Gkatzionis Apostolos , Yarmolinsky James , Bell Joshua A. , Chong Amanda H. W. , Paternoster Lavinia , Tilling Kate , Smith George Davey
Published: February 2023

Genetic studies of disease progression can be used to identify factors that may influence survival or prognosis, which may differ from factors that influence on disease susceptibility. Studies of disease progression feed directly into therapeutics for disease, whereas studies of incidence inform prevention strategies. However, studies of disease progression are known to be affected by collider (also known as “index event”) bias since the disease progression phenotype can only be observed for individuals who have the disease. This applies equally to observational and genetic studies, including genome-wide association studies and Mendelian randomisation (MR) analyses. In this paper, our aim is to review several statistical methods that can be used to detect and adjust for index event bias in studies of disease progression, and how they apply to genetic and MR studies using both individual- and summary-level data. Methods to detect the presence of index event bias include the use of negative controls, a comparison of associations between risk factors for incidence in individuals with and without the disease, and an inspection of Miami plots. Methods to adjust for the bias include inverse probability weighting (with individual-level data), or Slope-Hunter and Dudbridge et al.’s index event bias adjustment (when only summary-level data are available). We also outline two approaches for sensitivity analysis. We then illustrate how three methods to minimise bias can be used in practice with two applied examples. Our first example investigates the effects of blood lipid traits on mortality from coronary heart disease, while our second example investigates genetic associations with breast cancer mortality.
Uptake of community antiretroviral group delivery models for persons living with HIV in Arua district, Uganda: A parallel convergent mixed methods study
Authors: Muzeyi Wani , Aggrey Semeere , Kalibbala Dennis , Katairo Thomas , Semitala Fred C. , Katamba Achilles , Ayakaka Irene , Kalema Nelson
Published: February 2023

Community antiretroviral groups (CAGs) is one of the innovative and efficient differentiated service delivery models (DSDM) for reaching persons needing human immunodeficiency virus (HIV) treatment in the community. Since DSDM adoption in Uganda, evidence suggests better care outcomes for patients in DSDM compared to counterparts in routine health facility care. However, uptake of CAG models for eligible community groups of persons living with HIV (PLHIV) has been slow in Arua district, Uganda and stakeholders’ perceptions regarding its implementation unexplored. The objective of the study was to determine the uptake, barriers and facilitators influencing CAG model implementation in Arua district, Uganda. We conducted a parallel convergent mixed-methods study from March 2020 to December 2020 at Adumi health centre IV and Kuluva hospital in Arua district. We enrolled and extracted data for every fifth virally suppressed participant on antiretroviral therapy (ART) at the two health facilities. Data were analysed using STATA 13.0. Uptake was determined as the proportion of eligible PLHIV that were enrolled into a group. We performed logistic regression to determine factors associated with uptake. We conducted one focus group discussion per facility among healthcare workers involved in the management of PLHIV. We also conducted 7 focus group discussions among PLHIV across the two facilities. Thematic analysis was used to describe the data. A total of 399 PLHIV were eligible for CAG, 61.6% were female, and 44.9% were on dolutegravir (DTG) based regimen. Uptake was 6.8%, 95% CI (4.7–9.7) and was found to be significantly associated with being divorced or separated in a marriage (OR; 0.14, 95%CI; 0.02–0.92, P = 0.014). Members picking drugs in turns, comforting and encouraging others to take the drugs, and health workers advising them to join and stay with other group members were perceived as facilitators to uptake of community antiretroviral group delivery model. Having few and distant eligible members in the local area to form a group, lack of transport among the member to pick the drugs when it’s their turn, misunderstandings and lack of confidentiality amongst the members, and lack of partner disclosure were perceived as barriers to uptake of community antiretroviral group delivery model. Uptake of community antiretroviral group delivery model in Arua district is very low. There may be a need to support community antiretroviral group delivery models with income- generating activities, transport facilitation, closer community drug pick-up points and improved partner disclosure support mechanisms among married group members.
Deadly and venomous Lonomia caterpillars are more than the two usual suspects
Authors: González Camila , Ballesteros-Mejia Liliana , Díaz-Díaz Juana , Toro-Vargas Diana M. , Amarillo-Suarez Angela R. , Gey Delphine , León Cielo , Tovar Eduardo , Arias Mónica , Rivera Nazario , Buitrago Luz Stella , Pinto-Moraes Roberto H. , Sano Martins Ida S. , Decaëns Thibaud , González Mailyn A. , Kitching Ian J. , Rougerie Rodolphe
Published: February 2023

Caterpillars of the Neotropical genus Lonomia (Lepidoptera: Saturniidae) are responsible for some fatal envenomation of humans in South America inducing hemostatic disturbances in patients upon skin contact with the caterpillars’ spines. Currently, only two species have been reported to cause hemorrhagic syndromes in humans: Lonomia achelous and Lonomia obliqua. However, species identifications have remained largely unchallenged despite improved knowledge of venom diversity and growing evidence that the taxonomy used over past decades misrepresents and underestimates species diversity. Here, we revisit the taxonomic diversity and distribution of Lonomia species using the most extensive dataset assembled to date, combining DNA barcodes, morphological comparisons, and geographical information. Considering new evidence for seven undescribed species as well as three newly proposed nomenclatural changes, our integrative approach leads to the recognition of 60 species, of which seven are known or strongly suspected to cause severe envenomation in humans. From a newly compiled synthesis of epidemiological data, we also examine the consequences of our results for understanding Lonomia envenomation risks and call for further investigations of other species’ venom activities. This is required and necessary to improve alertness in areas at risk, and to define adequate treatment strategies for envenomed patients, including performing species identification and assessing the efficacy of anti-Lonomia serums against a broader diversity of species.
Influence of Na+ disorder on cytoplasmic conductivity and cellular electromagnetic (EM) energy absorption of human erythrocytes (PONE-D-21-36089)
Authors: Sudsiri Chadapust J. , Ritchie Raymond J.
Published: February 2023

Cytoplasmic conductivity of human erythrocytes may be significantly disturbed by the composition of the external suspending media. Effects of external NaCl on cytoplasmic conductivity of human erythrocyte (Human Red Blood Cells, HRBC) were investigated in a simple NaCl system. Using thermodynamic theory cytoplasmic conductivities could be calculated from internal [K+], [Na+], [Cl-] and [HCO3-]. Effect of cell volume and cell water changes were introduced and allowed for using the Debye-Hückel-Onsager relation and Walden’s rule of viscosity. Cell volume and cell water change of HRBCs were measured in suspending isotonic solutions with conductivities from 0.50 S m-1 up to hypertonic solutions of conductivity of 2.02 S m-1 at selected temperatures of 25°C (standard benchmark temperature) and 37°C (physiological temperature). In isotonic solutions, cytoplasmic conductivity of human erythrocyte decreases with rise in the external media ionic concentration and vice versa for hypertonic solutions. The HRBC is capable of rapidly regulating its volume (and shape) over quite a wide range of osmolality. Specific Absorption Rate (SAR, 900 MHz) values (W kg-1) of electromagnetic radiation are below safe limits at non-physiological 25°C but above legal limits at 37°C [National Council on Radiation Protection and Measurements, NCRP]. However, at 37°C under both hypertonic [Na+] and isotonic but low [Na+], SAR increases further beyond legal limits.